1
[Name of Document] DESCRIPTION
[Title of the Invention] HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET AND HIGH-STRENGTH ALLOYED HOT-DIP GALVANIZED STEEL SHEET HAVING EXCELLENT PLATING ADHESION, FORMABILITY, AND HOLE 5 EXPANDABILITY WITH TENSILE STRENGTH OF 980 MPa OR MORE AND MANUFACTURING METHOD THEREFOR [Technical Field] [0001]
The present invention relates to a high-tensile steel sheet having excellent
10 formability (ductility and hole expandability) and to an alloyed hot-dip galvanized steel sheet using TRIP (Transformation Induced Plasticity) phenomenon and a manufacturing method thereof.
This application claims priority on Japanese Patent Application No. 2011-216967, filed on September 30,2011, the content of which is incorporated herein by reference.
15 [Background Ait] [0002]
High strengthening of a steel sheet which is a raw material has been in progress so as to realize both of compatibility between a weight saving of a body, components, and the like of a vehicle, and safety. Generally, when the strength of the steel sheet increases,
20 formability (ductility and hole expandability) is damaged. Therefore, the balance of strength and formability is necessary in order to use the high-strength steel sheet for the members of the vehicles. For this requirement, hitherto, a so-called TRIP steel sheet using transformation induced plasticity of residual austenite has been suggested (for example, refer to Patent Literature 1 and Patent Literature 2). The high strength steel
25 sheet for the vehicle requires corrosion resistance depending on components to be applied. An alloyed hot-dip galvanized steel sheet is applied to such a case. However, Si is added

2
to the TRIP steel to improve the ductility. When the Si concentrated on the surface of the
steel sheet oxidizes, the TRIP steel has a problem in that galvanizing faults easily occur at
the time of hot-dip galvanizing.
[0003]
5 A manufacturing method of a high-strength alloyed hot-dip galvanized steel sheet
has been disclosed in Patent Literatures 3 and 4 which can achieve wettability improvement of plating and reduction of alloying temperature by performing Ni pre-plating on an Si-added high strength steel sheet and working a surface layer to activate. In this method, a hot-dip galvanized steel sheet and an alloyed hot-dip galvanized steel
10 sheet can be manufactured by re-heating and plating a cold-rolled steel sheet, in which a material as an original sheet is previously integrated, produced by a cold rolling-annealing process. [0004]
In addition, a technique has been proposed in Patent Literature 5 which produces a
15 high elongation-type alloyed hot-dip galvanized steel sheet by utilizing a Ni pre-plating technique. This method relates to manufacturing a high-strength steel sheet having excellent corrosion resistance by making steel consisting of ferrite and martensite by controlling steel components, annealing conditions, alloying hot-dip galvanizing conditions or the like and then performing hot-dip galvanizing.
20 [0005]
However, in the hot-dip galvanized steel sheet and the alloyed hot-dip galvanized steel sheet, the martensite, which is once generated, is softened when the steel sheet is re-heated in the galvanizing process, and thus a desired strength cannot be obtained. In this way, it is difficult to achieve both of high strengthening and formability, and a hot-dip
25 galvanized steel sheet and an alloyed hot-dip galvanized steel sheet having good corrosion resistance with high tensile strength of 980 MPa or more and excellent formability have

3
been desired.
[Prior Ait Literature(s)]
[Patent Literature(s)]
[0006] 5 [Patent Literature 1] JP 61-217529A
[Patent Literature 2] JP 5-59429A
[Patent Literature 3] JP 2526320B
[Patent Literature 4] JP 2526322B
[Patent Literature 5] JP 2006-283071A 10 [Summary of the Invention]
[Problem(s) to Be Solved by the Invention]
[0007]
The present invention is to solve the above-described problems and to provide a
high-strength hot-dip galvanized steel sheet and an alloyed hot-dip galvanized steel sheet 15 having excellent ductility and hole expandability by combining a rolling process with heat
treatment in a hot-dip galvanizing line.
[Means for Solving the Problem(s)]
[0008]
The present inventors examined in detail on a structure control due to heat 20 treatment and effects of working and heat treatment with respect to various steels in which
contents of C, Si, and Mn are varied. As a result, the present inventors have found that a
steel sheet having unique structures can be obtained by working and heat treatment using
heat treatment in continuous annealing, rolling working, and heat treatment during
subsequent plating treatment. In addition, the inventors have found that the steel sheet 25 can have ultimate tensile strength of 980 MPa or more which has been a probiem until now,
excellent formability (ductility and hole expandability), and plating property.

4
[0009]
The gist of the present invention are as follows.
[1] A high-strength hot-dip galvanized steel sheet having excellent plating adhesion,
formability, and hole expandability with an ultimate tensile strength of 980 MPa or more, 5 the hot-dip galvanized steel sheet comprising a hot-dip galvanized layer formed on a surface of a base steel sheet,
wherein the base steel sheet contains: by mass%,
C: 0.05% to 0.4%;
Si: 0.01% to 3.0%;
10 Mn: 0.1% to 3.0%;
Al: 0.01 to 2.0%; in which Si + Al > 0.5%
P: limited to 0.04% or less;
S: limited to 0.05% or less;
N: limited to 0.01% or less; and
15 a balance including Fe and inevitable impurities,
a microstructure of the base steel sheet contains 40% or more by total volume
fraction of martensite and bainite, 8% or more by volume fraction of residual austenite, and
a balance of the microstructure being ferrite or ferrite and 10% or less by volume fraction
ofpearlite,
20 the martensite contains 10% or more by total volume fraction of two or more
kinds of three kinds of martensites (1), (2), and (3) below, and
the hot-dip galvanized layer contains less than 7 mass% of Fe,
the martensite (1): C concentration (when there is a cementite precipitation, also including C in cementite); CM1 is less than 0.8 mass%, and nano-indentation test hardness 25 Hitl satisfies Expression 1.
Hitl/{-982.1 x (CM1)2 + 1676 x CM1 + 189} < 0.50 - Expression 1

5
the martensite (2): C concentration (when there is a cementite precipitation, also including C in cementite); CM2 is 0.8 mass% or more, and nano-indentation test hardness Hit2 satisfies Expression 2.
Hit2/{-982.1 x (CM2)2 + 1676 x CM2 + 189} < 0.50 - Expression 2
5 the martensite (3): C concentration (when there is a cementite precipitation, also
including C in cementite); CM3 is 0.8 mass% or more, and nano-indentation test hardness Hit3 satisfies Expression 3.
0.5 < Hit3/{-982.1 x (CM3)2 + 1676 x CM3 + 189} < 0.80 - Expression 3 [0010] 10 [2] The high-strength hot-dip galvanized steel sheet having the excellent plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to [1], wherein the base steel sheet further contains one or two or more of: by mass%,
Cr: 0.05 to 1.0%;
15 Mo: 0.05 to 1.0%;
Ni: 0.05 to 1.0%; and
Cu: 0.05 to 1.0%. [0011]
[3] The high-strength hot-dip galvanized steel sheet having the excellent plating
20 adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to [1], wherein the base steel sheet further contains one or two or more of: by mass%,
Nb: 0.005 to 0.3%;
Ti: 0.005 to 0.3%; and
25 V: 0.01 to 0.5%.
[0012]

6
[4] The high-strength hot-dip galvanized steel sheet having the excellent plating
adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to [1], wherein the base steel sheet further contains B: 0.0001 to 0.1% by mass%. 5 [0013]
[5] The high-strength hot-dip galvanized steel sheet having the excellent plating
adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa
or more according to [1], wherein the base steel sheet further contains one or two or more
of: by mass%,
10 Ca: 0.0005 to 0.01%;
Mg: 0.0005 to 0.01%; and
REM: 0.0005 to 0.01%. [0014]
[6] A high-strength alloyed hot-dip galvanized steel sheet having excellent plating
15 adhesion, formability, and hole expandability with an ultimate tensile strength of 980 MPa or more, the alloyed hot-dip galvanized steel sheet comprising an alloyed hot-dip galvanized layer formed on a surface of a base steel sheet,
wherein the base steel sheet contains: by mass%,
C: 0.05% to 0.4%;
20 Si: 0.01% to 3.0%;
Mn: 0.1% to 3.0%;
Al; 0.01 to 2.0%; in which Si + Al > 0.5%
P: limited to 0.04% or less;
S: limited to 0.05% or less;
25 N: limited to 0.01% or less; and
a balance including Fe and inevitable impurities,

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a microstructure of the base steel sheet contains 40% or more by total volume
fraction of mailensite and bainite, 8% or more by volume fraction of residual austenite, and
a balance of the microstructure being ferrite or ferrite and 10% or less by volume fraction
ofpearlite,
5 the mailensite contains 10% or more by total volume fraction of two or more
kinds of three kinds of martensites (1), (2), and (3) below, and
the alloyed hot-dip galvanized layer contains 7 to 15 mass% of Fe,
the mailensite (1): C concentration (when there is a cementite precipitation, also including C in cementite); CM1 is less than 0.8 mass%, and nano-indentation test hardness 10 Hitl satisfies Expression 1.
Hitl/{-982.1 x (CM1)2 + 1676 x CM1 + 189} < 0.50 - Expression 1
the martensite (2): C concentration (when there is a cementite precipitation, also
including C in cementite); CM2 is 0.8 mass% or more, and nano-indentation test hardness
Hit2 satisfies Expression 2.
15 Hit2/{-982.1 x (CM2)2 + 1676 x CM2 + 189} < 0.50 - Expression 2
the martensite (3): C concentration (when there is a cementite precipitation, also including C in cementite); CM3 is 0.8 mass% or more, and nano-indentation test hardness Hit3 satisfies Expression 3.
0.5 < Hit3/{-982.1 x (CM3)2 + 1676 x CM3 + 189} < 0.80 - Expression 3 20 [0015]
[7] The high-strength alloyed hot-dip galvanized steel sheet having the excellent
plating adhesion, formabiiity, and hole expandability with the ultimate tensile strength of
980 MPa or more according to [6], wherein the base steel sheet further contains one or two
or more of: by mass%,
25 Cr: 0.05 to 1.0%;
Mo: 0.05 to 1.0%;

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Ni: 0.05 to 1.0%; and Cu: 0.05 to 1.0%. [0016]
[8] The high-strength alloyed hot-dip galvanized steel sheet having the excellent
5 plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to [6], wherein the base steel sheet further contains one or two or more of; by mass%,
Nb: 0.005 to 0.3%;
Ti: 0.005 to 0.3%; and
10 V: 0.01 to 0.5%.
[0017]
[9] The high-strength alloyed hot-dip galvanized steel sheet having the excellent
plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to [6], wherein the base steel sheet further contains B: 0.0001 15 to0.1%bymass%. [0018]
[10] The high-strength alloyed hot-dip galvanized steel sheet having the excellent plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to [6], wherein the base steel sheet further contains one or two 20 or more of: by mass%,
Ca: 0.0005 to 0.01%; Mg: 0.0005 to 0.01%; and REM: 0.0005 to 0.01%. [0019] 25 [11] A manufacturing method of a high-strength hot-dip galvanized steel sheet having excellent plating adhesion, formability, and hole expandability with an ultimate tensile

9
strength of 980 MPa or more, the manufacturing method comprising:
with respect to a steel billet containing: by mass%,
C: 0.05% to 0.4%;
Si: 0.01% to 3.0%;
5 Mn: 0.1% to 3.0%;
Al: 0.01 to 2.0%; in which Si + Al > 0.5%
P: limited to 0.04% or less;
S: limited to 0.05% or less;
N: limited to 0.01% or less; and
10 a balance including Fe and inevitable impurities,
heating to 1200°C or higher and performing hot rolling at an Ar3 transformation temperature or higher;
performing cold rolling on a base steel sheet after the hot rolling at a reduction
ratioof40to70%;
15 annealing the base steel sheet after the cold rolling at 730 to 900°C;
cooling the base steel sheet after the annealing to a temperature of 650 to 750°C at
an average cooling rate of 0.1 to 200°C/second, and cooling the base steel sheet to 450°C
or lower from the temperature of 650 to 750°C at an average cooling rate of 20°C/second
or faster;
20 holding the base steel sheet cooled to the 450°C or lower in a range of 350 to
450°C for 120 seconds or longer;
cooling the base steel sheet held in the range of 350 to 450°C to 70°C or lower at an average cooling rate of 5°C/second or faster;
rolling the base steel sheet cooled to the room temperature at an elongation 25 percentage of 0.2 to 2%;
heating the rolled base steel sheet to "temperature of hot-dip galvanizing bath -

10
40"°C to "temperature of hot-dip galvanizing bath + 50"°C at an average temperature
rising rate of 10°C/second or faster;
dipping and hot-dip galvanizing the base steel sheet heated to the "temperature of
hot-dip galvanizing bath - 40"°C to "temperature of hot-dip galvanizing bath + 50"°C into 5 a hot-dip galvanizing bath; and
cooling the hot-dip galvanized steel sheet, which is hot-dip galvanized, to 70°C or
lower at an average cooling rate of 5°C/second or faster.
[0020]
[12] The manufacturing method of the high-strength hot-dip galvanized steel sheet 10 having the excellent plating adhesion, formability, and hole expandability with the ultimate
tensile strength of 980 MPa or more according to [11], wherein a hot-dip galvanizing bath
flows at a flow rate of 10 m/min or more and 50 m/min or less at the time of the hot-dip
galvanizing.
[0021] 15 [13] The manufacturing method of the high-strength hot-dip galvanized steel sheet
having the excellent plating adhesion, formability, and hole expandability with the ultimate
tensile strength of 980 MPa or more according to [11], wherein before being heated to the
"temperature of hot-dip galvanizing bath - 40"°C to "temperature of hot-dip galvanizing
bath + 50"°C, the base steel sheet is subjected to pickling, and then a surface of the base 20 steel sheet is polished and removed to a depth of 0.1 um or more and is pre-plated with 0.2
to2g/m2ofNi.
[0022]
[14] A manufacturing method of a high-strength alloyed hot-dip galvanized steel sheet
having excellent plating adhesion, formability, and hole expandability with an ultimate 25 tensile strength of 980 MPa or more, the manufacturing method comprising: with respect to a steel billet containing: by mass%,

11
C: 0.05% to 0.4%;
Si: 0.01% to 3.0%;
Mn: 0.1% to 3.0%;
Al: 0.01 to 2.0%; in which Si + Al > 0.5%
5 P: limited to 0.04% or less;
S; limited to 0.05% or less;
N: limited to 0.01% or less; and
a balance including Fe and inevitable impurities,
heating to 1200°C or higher and performing hot rolling at an Ar3 transformation 10 temperature or higher;
performing cold rolling on a base steel sheet after the hot rolling at a reduction ratioof40to70°/o;
annealing the base steel sheet after the cold rolling at 730 to 900°C;
cooling the base steel sheet after the annealing to a temperature of 650 to 750°C at 15 an average cooling rate of 0.1 to 200°C/second, and cooling the base steel sheet to 450°C or lower from the temperature of 650 to 750°C at an average cooling rate of 20°C/second or faster;
holding the base steel sheet cooled to the 450°C or lower in a range of 350 to
450°C for 120 seconds or longer;
20 cooling the base steel sheet held in the range of 350 to 450°C to 70°C or lower at
an average cooling rate of 5°C/second or faster;
rolling the. base steel sheet cooled to the room temperature at an elongation percentage of 0.2 to 2%;
heating the rolled base steel sheet to "temperature of hot-dip galvanizing bath -25 40"°C to "temperature of hot-dip galvanizing bath + 50"°C at an average temperature rising rate of 10°C/second or faster;

12
dipping and hot-dip galvanizing the base steel sheet heated to the "temperature of
hot-dip galvanizing bath - 40"°C to "temperature of hot-dip galvanizing bath + 50"°C into
a hot-dip galvanizing bath and performing alloying-heating treatment at "temperature of
hot-dip galvanizing bath - 40"°C or higher and 560°C or lower within 40 seconds; and
5 cooling the alloyed hot-dip galvanized steel sheet, which is subjected to the
alloying-heating treatment, to 70°C or lower at an average cooling rate of 5°C/second or faster. • [0023] [15] The manufacturing method of the high-strength alloyed hot-dip galvanized steel
10 sheet having the excellent plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to [14], wherein a hot-dip galvanizing bath flows at a flow rate of 10 m/min or more and 50 m/min or less at the time of the hot-dip galvanizing. [0024]
15 [16] The manufacturing method of the high-strength alloyed hot-dip galvanized steel sheet having the excellent plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to [14], wherein before being heated to the "temperature of hot-dip galvanizing bath - 40"°C to "temperature of hot-dip galvanizing bath + 50"°C, the base steel sheet is subjected to pickling, and then a surface
20 of the base steel sheet is polished and removed to a depth of 0.1 urn or more and is pre-plated with 0.2 to 2g/m2 of Ni. [Effect(s) of the Invention] [0025]
According to the present invention, it is possible to obtain a hot-dip galvanized
25 steel sheet and an alloyed hot-dip galvanized steel sheet having excellent formability with high strength and to remarkably contribute to the industry.

13
[Mode(s) for Carrying out the Invention] [0026]
The present invention will be described below in detail.
(Microstmcture of base steel sheet)
5 First, microstructures of a base steel sheet according to the present invention will
be described. The microstructures of the base steel sheet according to the present
invention include bainite, martensite, and a residual austenite. Further, the martensite
includes two or more kinds of three kinds of martensites (1), (2), and (3) defined below.
[0027]
10 Martensite (1): C concentration (when there is a cementite precipitation, also
including C in cementite). CM1 is less than 0.8 mass% and nano-indentation test hardness Hitl satisfies Expression 1.
Hitl/{-982.1 x (CM1)2 + 1676 x CM1 + 189} < 0.50 - Expression 1
Martensite (2): C concentration (when there is a cementite precipitation, also 15 including C in cementite). CM2 is 0.8 mass% or more and nano-indentation test hardness Hit2 satisfies Expression 2.
Hit2/{-982.1 x (CM2)2 + 1676 x CM2 + 189} < 0.50 - Expression 2
Martensite (3): C concentration (when there is a cementite precipitation, also including C in cementite). CM3 is 0.8 mass% or more and nano-indentation test hardness 20 Hit3 satisfies Expression 3.
0.5 < Hit3/{-982.1 x (CM3)2 + 1676 x CM3 + 189} < 0.80 - Expression 3 [0028]
Although the detailed reason is unclear, when two or more kinds of martensites
among these three kinds of martensites (1) to (3) are contained 10% or more by total
25 volume fraction, both of strength and hole expandability are achieved. The martensite,
which has the hardest structure of structures contained in the base steel sheet of the present

14
invention, is essential to ensure ultimate tensile strength of 980 MPa or more. On the other hand, in a hole expanding test and a bending test, since the martensite is a starting point of void formation, it is known that the martensite deteriorates hole expandability. Therefore, in order to ensure the hole expandability, deformation is prevented from 5 concentrating on a specific martensite grain by mixing two or more kinds of martensites among these three different kinds of martensites. As a result, a technique that does not deteriorate the hole expandability while contributing to higher strengthening has been found. This effect can be obtained when the total volume fraction of the two or more martensites among the three kinds of martensites is set to be 10% or more. From this
10 reason, the lower limit of the volume fraction of the three kinds of martensites (1) to (3) was set to be 10%. Preferably, the lower limit is 15% or more. [0029]
The martensite (1) is a tempered martensite, which is low in C concentration and is not so hard. The C concentration CM1 of the martensite (1) is less than 0.8 mass%.
15 When there is a cementite precipitation in the martensite (1), C in cementite which is precipitated in the martensite (1) is also contained. The cementite in the martensite mentioned herein may be either of a precipitation in or between martensite laths, so that the effect of the present invention is exhibited. This structure originates from a fresh martensite to be formed at the time of cooling to 70°C or lower after being held at 350 to
20 450°C in an annealing process of the manufacturing method of the present invention. The martensite (1) is a tempered martensite in which the fresh martensite formed at the time of cooling to 70°C or lower after being held at 350 to 450°C is tempered during dipping treatment into a hot-dip galvanizing bath or alloying treatment. [0030]
25 The C concentration CM1 of the martensite (1) is less than 0.8 mass%. This also
includes a case in which C concentration was reduced to less than 0.8 mass% when C in

15
the fresh martensite was diffused into austenite during the dipping treatment into the hot-dip galvanizing bath or the alloying treatment and thus the fresh martensite was tempered even though C concentration of the fresh martensite was 0.8 mass% or more, in addition to a case in which C concentration of the fresh martensite formed at the time of 5 cooling to 70°C or lower after being held at 350 to 450°C was less than 0.8 mass%. [0031]
Since the martensite (1) has the C concentration CM! as low as less than 0.8 mass% and is tempered, it is the softest among three kinds of martensites (1) to (3). Nano-indentation test hardness Hitl of the martensite (1) satisfies Expression 1. When
10 the volume fraction of the martensite (1) is 60% or more of a microstructure of the base steel sheet, a volume fraction of ferrite and residual austenite becomes too low, and the ductility deteriorates, so that the upper limit is preferably 60%. [0032]
The martensite (2) has a high C concentration, but is martensite which is softened
15 by tempering, C concentration CM2 of the martensite (2) is 0.8 mass% or more. When there is a cementite precipitation in the martensite (2), C in the cementite which is precipitated in the martensite (2) is also contained. Similarly, the cementite in the martensite may be either of precipitation in or between martensite laths. The martensite (2) originates from strain-induced transformation martensite which is induced by the
20 rolling work and into which a part of a residual austenite is transformed. While the base steel sheet is held at a temperature range of 350 to 450°C after annealing, bainite transformation of the microstructure in the base steel sheet proceeds and thus C is diffused into a non-transformed austenite. A residual austenite, in which C is concentrated, is formed in the base steel sheet which is cooled to 70°C or lower. By strain-induced
25 transformation of the residual austenite, in which C is concentrated, by rolling, martensite which is the origin of the martensite (2) can be obtained. The Martensite (2) is a

16
tempered martensite in which the strain-induced transformation martensite generated by
the rolling ;s tempered during the dipping treatment into the hot-dip galvanizing bath or the
alloying treatment.
[0033]
5 Like the martensite (1), the martensite (2) is a tempered martensite, but is harder
than the martensite (1) since the C concentration is high. Nano-indentation test hardness Hit2 of the martensite (2) satisfies Expression 2. When a volume fraction of the martensite (2) is 40% or more of the microstructure of the base steel sheet, the ductility deteriorates, so that the upper limit is preferably set to be 60%.
10 [0034]
The martensite (3) is martensite which is high in C concentration, is not tempered, or is low in a quantity of tempering. C concentration CM3 of the martensite (3) is 0.8 mass% or more. When there is a cementite precipitation in the martensite (3), C in the cementite which is precipitated in the martensite (3) is also contained. Similarly, the
15 cementite in the martensite may be either of precipitation in or between martensite laths. The martensite (3) is a fresh martensite which is formed by transforming at the time of cooling to 70°C or lower after the hot-dip galvanizing or the alloying-heating treatment. In addition, the martensite (3) is also martensite remaining in a state of fresh martensite without being tempered substantially during the alloying-heating treatment or the alloying
20 treatment (not in a state of martensites (1) and (2)). [0035]
The martensite (3) is the hardest structure of three kinds of martensites (1) to (3). Nano-indentation test hardness Hit3 of the martensite (3) satisfies Expression 3. For this reason, the martensite (3) contributes to high strengthening, but deteriorates the hole
25 expandability. Accordingly, in order to achieve both of the strength and formability, the upper limit of the martensite (3) is 10% in the volume fraction of the microstructure of the

17
base steel sheet. However, when the volume fraction of the martensite (3) becomes too
small, it is difficult to ensure strength which is ultimate tensile strength of 980 MPa or
more, so that the lower limit is preferably set to be 3% or more.
[0036]
5 Bainite is effective for ensuring the strength. When a high strength steel sheet
having tensile strength exceeding 980 MPa contains martensite and bainite of 40% or more by total volume fraction, it is possible to ensure the strength and to obtain the high hole expandability. When the total volume fraction is less than 40%, the tensile strength is less than 980 MPa. Accordingly, the lower limit was set to be 40%.
10 [0037]
The residual austenite is a structure to raise ductility, particularly uniformly elongation by transformation-induced plasticity. In order to obtain particularly good elongation, it is necessary to contain the residual austenite of 8% or more by volume fraction. Furthermore, due to transform into martensite by working, the residual austenite
15 also contributes to obtaining of the high strengthening. [0038]
In the microstructure of the base steel sheet of the present invention, ferrite is not essential. However, since the ferrite causes the improvement of ductility, it may be contained. At the time of annealing, it is possible to control the volume fraction of ferrite
20 by performing two-phase annealing. Furthermore, it is possible to control the volume fraction of ferrite by cooling after annealing, However, when the fraction of ferrite increases, the strength decreases. Although the high strengthening can be obtained by precipitation strengthening and solid solution strengthening, the volume fraction of ferrite is preferably 40% or less.
25 [0039]
Pearlite may be contained as long as the volume fraction is 10% or less. When

18
the volume fraction of pearlite exceeds 10%, the strength and ductility are reduced.
Therefore, the upper limit was set to be 10%.
[0040]
Furthermore, each phase of the microstructures such as martensite, bainite, 5 austenite, pearlite, and ferrite can be identified and their locations and volume fraction can be observed and quantitatively measured using an optical microscope having a magnification of 1000 times and a scanning and transmission electron microscope having a magnification of 1000 times to 100000 times after a cross section of the steel sheet in a rolling direction or a cross section in the right angle direction of the rolling direction is
10 etched using a Nital reagent and the reagent as disclosed in JP 59-219473A. The area fraction of each structure can be obtained by observing 20 or more fields and applying the point-count method or image analysis. Then, the obtained area fraction is defined as the volume fraction of each structure. [0041]
15 The classification method of three kinds of martensites (1) to (3) is hardness and
C concentration. The hardness may be obtained by measuring nano-indentation testing hardness for three or more points in martensite grains and calculating an average hardness Hit. In the base steel sheet according to the present invention, since a large amount of additive elements are contained, a crystal grain diameter is small. Moreover, in the base
20 steel sheet according to the present invention, there is a case in which an indentation size is greater than the grain diameter of martensite grains in measurement using a Vickers hardness test. Therefore, hardness measurement of a micro-region was performed by a nano-indenter. Samples cut out parallel to the rolling direction are embedded and then are subjected to mirror-polishing and electrolytic polishing. Then, the hardness
25 measurement was performed on the polished samples. As test conditions, an indentation depth was measured under the condition of 50 nm using a Berkovich-type indenter.

19
Furthermore, this test method is small in an indentation depth, and is sensitive to relation
between the grain diameter of martensite and the indentation size, or surface irregularities.
Therefore, as a preliminary test, the electrolytic polishing in various conditions and the
hardness measurement in the condition with varying an indentation depth are performed, 5 and conditions for obtaining a most reproducible good value was set as test conditions.
[0042]
The C concentration of martensite grains may be measured by any measuring
method which guarantees precision under the condition of obtaining an accurate
decomposition concentration. For example, the C concentration of martensite grains can 10 be obtained by carefully measuring the C concentration at a pitch of 0.5 urn or below using
EPMA atta5hed to FE-SEM. Therefore, martensites (1) to (3) are classified according to
the hardness and the C concentration.
[0043]
Furthermore, in order to distinguish these martensites (1) to (3), Expressions 1 to 15 3 use a relational expression between amounts of C CMl to CM3 and nano-indentation test
hardness Hit in each martensite. Denominators of the left sides of Expressions 1, 2, and 3,
which are input values of C concentration represent hardness of carbides-free martensite
(fresh martensite) of the C concentration. The hardness of the martensite contained in the
base steel sheet of the present invention becomes lower than the hardness of a fresh 20 martensite by precipitation of cementite at grains and tempering. Therefore, the
classification is performed by taking a ratio between hardness of a fresh martensite of
denominator and hardness of martensite of a steel sheet.
[0044]
(Chemical composition of base steel sheet)
25 Next, a description of reasons for restricting the amounts of the compositions of
the base steel sheet in the present invention will be described. Moreover, % in the

20
composition represents % by mass. [0045]
C: C is added as an element which increases strength of steel and stabilizes a residual austenite to improve ductility. When the content is less than 0.05%, it is difficult 5 to ensure tensile strength of 980 MPa or more. Ductility, weldability, and toughness are remarkably deteriorated by excessive addition exceeding 0.40%. Therefore, the content of C was set to be 0.05 to 0.4%. A more preferred range is 0.13% to 0.3%. [0046]
Si: Si is an element useful for increasing the strength of the steel sheet by
10 solid-solution strengthening. In addition, Si is an essential element which has an effect for promoting concentration of C in austenite during bainite transformation and generates a residual austenite while annealing, in order to suppress the formation of cementite. These effects are not exhibited when the content is less than 0.01% and scale exfoliation and chemical convertibility generated in hot rolling are remarkably deteriorated by excessive
15 addition exceeding 3.0%. Thus, the content of Si was set to be 0.01 to 3.0%. [0047]
Mn: Mn is an element effective for improving hardenability. An effect of increasing the hardenability is not sufficiently exhibited when the content is less than 0.1% and the toughness is deteriorated by excessive addition exceeding 3.0%. Accordingly, the
20 content of Mn was set to be 0.1 to 3.0%. [0048]
Al: Al is an element having a function of deoxidizer. In addition, Al is a ferrite stabilizing element like Si and may be also used as an alternative of Si. Such an effect is not exhibited when the content is less than 0.01% and the toughness is deteriorated by
25 excessive addition exceeding 2.0%. Therefore, the content of Ai was set to be 0.01 to 2.0%.

21
[0049]
Ai + Si: Al and Si are elements having the same functions of ferrite stabilization
and cementite suppression. Accordingly, a total additive amount of Al and Si is
important. When the total additive amount is 0.5% or less, the function of stabilizing the 5 ferrite and suppressing the cementite becomes weak. Therefore, the content was added
with an amount larger than 0.5%.
[0050]
P: P is an impurity element which segregates at grain boundaries to make grain
boundary strength lower, thereby deteriorating the toughness. Thus, the content is 10 preferably reduced. The upper limit of the content of P was limited to 0.04% in
consideration of a current refining technology and manufacturing costs. The lower limit
value of P is not particularly determined, but when the lower limit value is less than
0.0001%, it is disadvantageous economically, so this value is preferably set to the lower
limit value. 15 [0051]
S: S is an impurity element which deteriorates hot workability and toughness, and
the content is preferably reduced. Accordingly, the upper limit was limited to 0.05%.
The lower limit value of S is not particularly determined, but when the lower limit value is
less than 0.0001%, it is disadvantageous economically, so this value is preferably set to the 20 lower limit value.
[0052]
N: N forms coarse nitrides to deteriorate bendability and hole expandability.
Therefore, it is necessary to suppress the additive amount. The reason is because the
tendency becomes remarkable when the content of N exceeds 0.01%. Thus, the content 25 of N was in a range of 0.01% or less. In addition, this causes blowholes to occur at the
time of welding, so the less the better. The effect of the present invention is exhibited

22
without particularly determining the lower limit, but when the content of N is less than
0.0005%, the manufacturing cost dramatically increases, so this value is a substantial lower
limit.
[0053]
5 Further, one or two or more elements of Cr, Mo, Ni, and Cu may be added.
These elements are elements effective for improving ductility and toughness. However, when the content of Cr, Mo, Ni, and Cu exceeds 1.0%, the toughness can be impaired due to an increase in strength. Accordingly, the upper limit of these elements was set to be 1.0%. Further, in order to improve the ductility and toughness, the necessary content of
10 Cr is 0.05% or more, the necessary content of Mo is 0.05% or more, the necessary content of Ni is 0.05% or more, and the necessary content of Cu is 0.05% or more, so these values are set to the lower limit value, respectively. [0054]
Further, one or two or more elements of Ti, Nb, and V may be added. These
15 elements are elements which form fine carbonitrides and are effective for suppressing coarsening of crystal grains, ensuring the strength, and improving the toughness. In order to ensure the strength and to improve the toughness, it is necessary to add 0.005% or more Ti and Nb and 0.01% or more V. However, when these elements are excessively added, a precipitate becomes coarse and the toughness may be deteriorated. Accordingly, the
20 additive amount of Nb and Ti is preferably set to be 0.3% or less, and the additive amount of V is preferably set to be 0.5 or less. [0055]
B: B is an element which segregates at grain boundaries to suppress grain boundary segregation of P and S. In addition, this element is also effective for improving
25 the hardenability. However, when the content of B exceeds 0.1%, a coarse precipitate occurs at the grain boundaries to impair the hot workability and the toughness.

23
Accordingly, the content of B is set to be 0.1% or lower. Further, in order to enhance the
ductility, toughness, and hot workability and to improve the hardenability by the
strengthening of the grain boundaries, the addition of B is preferably 0.0001% or more.
[0056]
5 Further, one or two or more elements of Ca, Mg, and REM may be added. These
elements are elements effective for controlling sulfide forms to suppress the deterioration of the hot workability and toughness due to S. REM indicates a rare earth metal. However, even when these elements are excessively added, since the effect is saturated, it is preferable that 0.01% or less Ca, 0.01% or less Mg, and 0.01% or less REM be added,.
10 respectively. In order to improve the toughness, 0.0005% or more Ca, 0.0005% or more Mg, and 0.0005% or more REM are preferably added, respectively. Further, in the present invention, REM is generally added in a mischmetal, which in addition to La and Ce may also contain other lanthanoid series elements in combination. The effects of the invention are exhibited even when the lanthanoid series elements other than La and Ce are
15 contained as inevitable impurities. However, the effects of the present invention are exhibited even when metals such as La and Ce are added. [0057] (Chemical composition of hot-dip galvanized layer and alloyed hot-dip galvanized layer)
In the present invention, a hot-dip galvanized layer formed on the surface of the
20 base steel sheet contains less than 7 mass% Fe, the balance being Zn and inevitable impurities. In addition, an alloyed hot-dip galvanized layer contains 7 to 15 mass% Fe, and the balance being Zn and inevitable impurities. The hot-dip galvanized layer and the alloyed hot-dip galvanized layer may further contain Al of 0.01 to 0.5 mass% and more preferably, may contain Al of 0.05 to 0.3 mass%. Further, the galvanizing bath may
25 contain Fe, Mg, Mn, Si, Cr and the like in addition to pure zinc and Al, [0058]

24
In a case where spot weldability and a coating property are desired, it is possible to improve these properties by forming the alloyed hot-dip galvanized layer containing 7 to 15 mass% Fe on the surface of the base steel sheet. Specifically, when the base steel sheet is subjected to the allowing treatment while being dipped in the galvanizing bath, Fe 5 is incorporated into the galvanized layer, and thus the high-strength alloyed hot-dip galvanized steel sheet having an excellent coating property and spot weldability can be obtained. When the content of Fe after the alloying treatment is less than 7 mass%, the spot weldability becomes insufficient. On the other hand, when the content of Fe exceeds 15 mass%, the adhesion of the galvanized layer itself is impaired, and the galvanized layer
10 is broken and dropped out in machining, thereby causing scratches when forming by adhering to a mold. Accordingly, the content of Fe contained in the galvanized layer during the alloying treatment is within a range of 7 to 15 mass%. [0059]
Furthers in a case where the alloying treatment is not performed, even when the
15 content of Fe contained in the galvanized layer is less than 7 mass%3 the corrosion resistance, the formability, and hole expandability which are effects obtained by the alloying are good except for the spot welding. [0060]
Further, the galvanized layer may contain Al, Mg, Mn, Si, Cr, Ni, Cu or the like in
20 addition to Fe. [0061]
In order to measure the content of Fe and Al contained in the galvanized layer, a method of dissolving the galvanized layer with an acid and chemically analyzing the dissolved solution may be used. For example, with respect to the alloyed hot-dip
25 galvanized steel sheet cut into 30 mm x 40 mm, only the galvanized layer is dissolved while suppressing elution of the base steel sheet with an inhibitor-added 5% HC1 aqueous

25
solution. Then, the content of Fe and Al is quantified using signal intensities obtained by ICP emission analysis of the dissolved solution and a calibration curve prepared from concentration-known solutions. Further, in consideration of measured variation of samples, an average value is employed obtained by measuring at least three samples which 5 are cut out from the same alloyed hot-dip galvanized steel sheet. [0062]
The coated amount of the plating is not particularly limited, but is preferably 5 g/m or more in the coated amount on a single surface of the base steel sheet from the viewpoint of corrosion resistance. In addition, the coated amount on the single surface is
10 preferably no greater than 100 g/m2 from the viewpoint of ensuring the plating adhesion. [0063] (Manufacturing method of steel sheet)
Next, a manufacturing method will be described.
In the present invention, the steel consisting of the above compositions is casted
15 by melting in a conventional manner. The obtained steel billet (cast slab) is subjected to hot rolling. The cast slab is directly cooled or once cooled and then is heated to 1200°C or higher, and the hot rolling is finished at an Ar3 transformation temperature or higher. [0064]
The base steel sheet (hot-rolled steel sheet) subjected to the hot rolling may be
20 coiled at a temperature region of 700°C or lower. When the coiling temperature exceeds 700°C, the structure of the hot-rolled steel sheet becomes a coarse ferrite or pearlite structure. As a result, a structure of a final steel sheet becomes a non-uniform structure, and thus it is difficult to obtain good hole expandability. Therefore, the upper limit of the coiling temperature is set to be 700°C. More preferably, the upper limit is 650°C or
25 lower and, most preferably, is 550°C at which bainite-single phase is formed. The lower limit of the coiling temperature is not particularly defined. However, when the lower

26
limit is lower than 300°C, the strength of the hot-rolled sheet increases and causes
interference of a cold rolling in some cases. Therefore, the lower limit is preferably
300°C or higher.
[0065]
5 Then, the base steel sheet (hot-rolled steel sheet) is subjected to pickling treatment
as necessary and then is subjected to the cold rolling at a reduction ratio of 40 to 70%. In order to refine a microstructure after annealing, the cold rolling is performed at the reduction ratio of 40% or more. On the other hand, when the reduction ratio of the cold rolling exceeds 70%, a load is increased by work hardening to cause a loss of productivity.
10 Accordingly, the reduction ratio of the cold rolling is set to be 40 to 70%. [0066]
After the cold rolling, the base steel sheet is annealed" at 730 to 900°C. In order to control the microstructure of the base steel sheet, a heating temperature of the annealing and cooling conditions are very important in the present invention. The annealing after
15 the cold rolling is performed at the range of 730 to 900°C to obtain austenite in which C is sufficiently concentrated. When the annealing temperature is lower than 730°CS carbides are melted and remain, and thus a required amount of austenite cannot be obtained. When the annealing temperature exceeds 900°C, it is uneconomical. Further, in a case where the annealing temperature exceeds 900°C, recrystallization proceeds and a grain
20 diameter becomes larger, thereby deteriorating toughness and ductility. Therefore, the annealing temperature is set to be 730 to 900°C. [0067]
After being subjected to the annealing, the base steel sheet is cooled to a temperature of 600 to 750°C at an average cooling rate of 0.1 to 200°C/second.
25 Thereafter, the base steel sheet is cooled to a temperature of 450°C or lower from a temperature of 600 to 750°C at an average cooling rate of 20°C/second or faster. The

27
purpose of cooling the base steel sheet to the temperature of 600 to 750°C at the average cooling rate of 0.1 to 200°C/second from the temperature region of the annealing is to suppress formation of pearlite which occurs during the cooling process. When the cooling rate is slower than 0.1°C/second, it is difficult to avoid pearlite transformation and 5 a part or all of the austenite is transformed into the pearlite, so that it is difficult to obtain the high strength of 980 MP or more. Therefore, the average cooling rate from the temperature region of the annealing to the temperature of 600 to 750°C is set to be 0.1°C/second or faster. On the other hand, the cooling at the cooling rate of 200°C/second or faster causes not only saturation of the effect but also excessive facility
10 investment, so that economic efficiency becomes poor. Therefore, the upper limit of the cooling rate is set to be 200°C/second. [0068]
When the cooling rate from the temperature of 600 to 750°C to the temperature of 450°C or lower is slow, bainite transformation proceeds and a large amount of carbides are
15 formed in the bainite structure, so that the austenite is decomposed and thus the ductility becomes weak. In addition, since three kinds of martensites (1) to (3) may not be obtained, the balance of the strength and the hole expandability is low. For this reason, it is necessary to cool at the average cooling rate of 20°C/second or faster. Furthermore, the upper limit is not limited, but when the cooling rate is excessively raised, manufacturing
20 cost increases, and thus the upper limit is preferably 200°C/second or slower. [0069]
Next, the base steel sheet is held at the range of 350 to 450°C for 120 seconds or longer. Further, as described above, when the cooling is performed from the temperature of 600 to 750°C to the temperature of 450°C or lower, a cooling stop temperature is set to
25 be 350°C or higher, and then the base steel sheet may be held at the range of 350 to 450°C for 120 seconds or longer. Alternatively, when the cooling is performed from the

28
temperature of 600 to 750°C to the temperature of 450°C or lower, the cooling stop temperature is set to be lower than 350°C, and then the base steel sheet is re-heated and may be held at the range of 350 to 450°C for 120 seconds or longer. The reason is because the holding at the temperature region of 350 to 450°C is to control the stability of 5 austenite. When the holding time is short, the stabilization of austenite is not achieved and a residual austenite 8% or more by volume fraction cannot be obtained. As a result, the balance of the strength and the ductility will be failed. On the other hand, the holding for a long time causes excessive stabilization of the residual austenite, and thus martensite is not formed in the cooling process to room temperature to be subsequently performed and
10 three kinds of martensites (1) to (3) are not obtained. Accordingly, the holding time is preferably set to be 1000 seconds or shorter. [0070]
Subsequently, the base steel sheet is cooled once to 70°C or lower at the average cooling rate of 5°C/second or faster. A cooling attainment temperature may be room
15 temperature. However, since the attainment temperature varies depending on the season, the attainment temperature may be 70°C or lower in terms of securing materials and may vary depending on the season. In addition, the average cooling rate up to 70°C needs to be set to be 5°C/second or faster. The upper limit is not particularly determined, but the cooling at the cooling rate over 200°C/second causes not only saturation of the effect but
20 also large facility investment, so that economic efficiency becomes poor. Therefore, the upper limit of the cooling rate is preferably set to be 200°C/second or slower. For this reason, a part of austenite is transformed into martensite. By performing such heat treatment, a composite structure of bainite, a residual austenite, and martensite can be obtained. However, ferrite may be partially contained. Further, the martensite obtained
25 by the cooling up to the room temperature is a fresh martensite which is the origin of the martensite (1).

29
[0071]
Next, the base steel sheet cooled to 70°C or lower is rolled. A part of residual austenite in the base steel sheet is transformed by the rolling working, and thus a strain-induced transformation martensite is generated. Thus, the strain-induced 5 transformation martensite obtained by the rolling is the origin of the martensite (2). The austenite remaining at the room temperature contains C of 0.8 mass% or more, and the strain-induced transformation martensite formed by the transformation of the above austenite becomes hard. In order to obtain a sufficient strain-induced transformation martensite, an elongation percentage (reduction ratio) of the rolling is set to be 0.2 to 2%.
10 The effect is not sufficient when the elongation percentage is less than 0.2%, and the yield ratio is significantly increases and the elongation deteriorates when the elongation percentage exceeds 2%. [0072]
Next, after being subjected to Ni pre-plating as necessary, the base steel sheet is
15 subjected to galvanizing or galvanizing and alloying-heating treatment. In the case of performing the Ni pre-plating, after the base steel sheet is subjected to the pickling, the surface of the base steel sheet is removed by polishing to 0.1 urn or more in depth and then Ni is pre-plated on the surface of the base steel sheet with 0.2 to 2 g/m . In order to suppress of galvanizing faults and perform the alloying, the surface of the steel sheet is
20 preferably subjected to the polishing or the Ni pre-plating. The reason is because oxides are easily formed on the surface of the base steel sheet and the galvanizing faults and the alloying treatment delay of the hot-dip galvanizing easily occur through a plurality of heating treatment processes.
After the annealing, oxides of Si, Mn and the like exist in the surface layer of the
25 base steel sheet in some cases. When these oxides exist, even if the base steel sheet is assumed to be subjected to the Ni pre-plating, the galvanizing faults occur in some cases.

30
For this reason, it is necessary to remove the oxides by performing the polishing. Since the effect becomes remarkable by polishing to 0.1 jam or more in depth from the surface layer of the base steel sheet, a polishing quantity is set to be 0.1 (am. The upper limit is not particularly determined. However, since the steel sheet becomes thin and product 5 yield is reduced according to the polishing quantity, the polishing quantity is preferably small.
When a Ni-coated amount is set to be 0.2 to 2 g/m , the galvanizing faults are suppressed at the time of subsequent hot-dip galvanizing. In the Ni-coated amount of less than 0.2 g/m , since the effect of suppressing the galvanizing faults is not sufficiently
10 obtained, the lower limit thereof is set to be 0.2 g/m2. The effect of suppressing the galvanizing faults can be obtained without specifically determining the upper limit, but the upper limit exceeding 2.0 g/m causes not only saturation of the effect but also excessive facility investment, so it is undesirable that the economic efficiency becomes poor. In addition, this requires the excessive facility investment or an operation dropped extremely
15 in sheet-passing speed is required, so it is undesirable that the economic efficiency becomes poor. [0073]
A temperature of the base steel sheet to be dipped in the hot-dip galvanizing bath is in a range from a temperature that is lower by 40°C compared with the temperature of
20 the hot-dip galvanizing bath to a temperature that is higher by 50°C compared with the temperature of the hot-dip galvanizing bath. When the temperature of the base steel sheet to be dipped is below "temperature of hot-dip galvanizing bath - 40" °C, the heat loss upon dipping into the galvanizing bath becomes large and a part of the molten zinc is solidified, thereby leading to a deterioration of the galvanized external appearance in some cases. In
25 addition, when the temperature of the base steel sheet is above "temperature of hot-dip galvanizing bath + 50"°C, operational problems associated with a temperature rise of the

31
galvanizing bath are induced. Further, the temperature of the galvanizing bath is managed to 440 to 470°C. The decrease in temperature of the galvanizing bath leads to solidification of the hot-dip galvanizing existing in the bath and becomes a cause of the galvanizing faults or becomes a cause of appearance deterioration. 5 [0074]
Thus, the rolled base steel sheet should be heated to the "temperature of hot-dip galvanizing bath - 40"°C to the "temperature of hot-dip galvanizing bath + 50"°C. Here, the base steel sheet is heated at an average temperature rising rate of 10°C/second or higher. Here, when the heating rate is slower than 10°C/second, the surface of the base steel sheet
10 is polished and removed while the Ni pre-plating and the induced strain is relaxed, so that alloying-promoting effect cannot be obtained. In addition, when the heating temperature is lower than the "temperature of hot-dip galvanizing bath - 40", the galvanizing faults easily occur during the hot-dip galvanizing. When the heating temperature is above the "temperature of hot-dip galvanizing bath + 50"°C, the surface of the base steel sheet is
15 polished and removed and the induced strain is relaxed, so that the alloying-promoting effect cannot be obtained. [0075]
In a hot-dip galvanizing tank, it is preferable that a jet flow of 10 m/min or more and 50 m/min or less be provided in the galvanizing bath to suppress the galvanizing faults
20 and to promote the alloying. Scum, which is an oxide film of Zn or Al, is floated on the surface of the galvanizing bath. When the oxide film remains on the surface of the base steel sheet in large amounts, the scum adheres to the surface of the base steel sheet at the time of dipping in the galvanizing bath and the galvanizing faults easily occur. Further, the scum adhering to the steel sheet causes not only the galvanizing faults but also the
25 alloying delay. [0076]

32
This property is particularly remarkable in the steel sheet containing a lot of Si and Mn. The detailed mechanism is unclear, but it is considered that the galvanizing faults and the alloying delay are facilitated by reacting between the oxide of Si or Mn, which is formed on the surface of the base steel sheet, and the scum that is similarly the 5 oxide. The reason for setting the flow rate of the jet flow to be 10 m/min or more and 50 m/min or less is because the suppressing effect of the galvanizing faults due to the jet flow cannot be obtained at the flow rate slower than 10 m/min. The reason for setting the flow rate to be 50 m/min or less is because the suppressing effect of the galvanizing faults is saturated and a high cost due to the excessive facility investment is also avoided.
10 [0077]
In addition, the galvanizing bath may contain Fe, Al, Mg, Mn, Si, Cr and the like in addition to pure zinc. [0078]
Then, when the base steel sheet is subjected to the hot-dip galvanizing or the
15 hot-dip galvanizing and the alloying treatment by dipping in the hot-dip galvanizing bath, the martensite in the base steel sheet is tempered. That is, as described above, the fresh martensite which is the origin of the martensite (1) and the strain-induced transformation martensite which is the origin of the martensite (2) are contained in the base steel sheet to be dipped into the hot-dip galvanizing bath. When the base steel sheet is subjected to the
20 dipping and the alloying heat treatment in the hot-dip galvanizing bath, the fresh martensite and the strain-induced transformation martensite formed previously in the base steel sheet are tempered. As a result, the martensite (1) and the martensite (2) are formed. [0079]
Next, the hot-dip galvanized steel sheet subjected to the hot-dip galvanizing or the
25 alloyed hot-dip galvanized steel sheet subjected to the hot-dip galvanizing and the alloying treatment is cooled to 70°C or lower. The cooling attainment temperature may be set to

33
be room temperature. However, since the attainment temperature varies depending on the season, the attainment temperature may be 70°C or lower in terms of securing materials and may vary depending on the season. In addition, the average cooling rate up to 70°C needs to be set to be 5°C/second or faster. The upper limit is not particularly determined, 5 but the cooling at the cooling rate over 200°C/second causes not only the saturation of the effect but also the large facility investment, so that it is economically undesirable. Therefore, the upper limit of the cooling rate is preferably set to be 200°C/second or slower. By the cooling, a part of residual austenite in the base steel sheet is transformed into martensite. The martensite generated in this way becomes a martensite (3) which has
10 the hardest structure. [0080]
In only the heat treatment, only the decomposition of the residual austenite is caused. However, in the present invention, the steel sheet is previously subjected to the rolling and thus the residual austenite is further processed. As a result, a part of residual
15 austenite is transformed into martensite while the cooling after the heat treatment. The martensite (3) obtained as a result becomes a reinforcing structure to achieve high strengthening. The detailed mechanism is unclear, but when the structure of the steel sheet subjected to the rolling was compared with the structure of the steel sheet, which was not subjected to temper rolling, in detail, this martensite was not observed in the steel sheet
20 which was not subjected to the rolling. For this reason, it is assumed that a dislocation induced while the rolling contributes to the martensite transformation at the time of the heat treatment and subsequent treatment. [0081]
Furthermore, in order to obtain the martensite (3), it is necessary to heat the base
25 steel sheet to the temperature of "temperature of hot-dip galvanizing bath - 40" (°C) or higher and 560°C or lower. In the heating at the "temperature of hot-dip galvanizing bath

34
- 40" (°C) or lower, the martensite cannot be obtained while the cooling to be performed subsequently. On the other hand, when the base steel sheet is heated to the temperature exceeding 560°C5 carbides are remarkably precipitated and the austenite is decomposed, and thus it is difficult to obtain the amount of residual austenite which is required for 5 elongation improvement. For this reason, in the case of performing the hot-dip galvanizing, the heating temperature of the base steel sheet is set to be 560°C or lower. In addition, when the time required for the alloying heat treatment is long, the austenite is decomposed. Accordingly, an alloying treatment time is preferably set to be 40 seconds or shorter.
10 [0082]
Further, in a facility such as a continuous hot-dip galvanizing facility for continuously performing the heat treatment and plating, the steel sheet is not cooled to the room temperature in a middle course and is not subjected to the rolling in a middle course. Consequently, structure controls of separately manufacturing three kinds of martensites as
15 in the present invention and of ensuring the residual austenite could not be performed. Accordingly, it was difficult to achieve all of the strength, ductility, and hole expandability ' with a high level. [0083]
In addition, when the surface layer of the base steel sheet is pre-plated with Ni
20 after being polished and removed to 0.1 um or thicker, the alloying is promoted during the alloying-heating treatment after the galvanizing to lower the heating temperature at the time of the alloying treatment. For this reason, the cementite is not generated during the alloying-heating treatment and the deterioration of the hole expandability is avoided. The mechanism of the alloying promotion is unclear, but it is considered that the surface is
25 activated due to the strain induced into the surface layer of the steel sheet by the polishing. Examples of methods of polishing and removing the surface layer of the base steel sheet

35
may include brush polishing, sandpaper polishing, or mechanical polishing. The method of the Ni pre-plating may be any one of electroplating, dipping-plating, and spraying-plating, and plating weight is preferably about 0.2 to 2 g/m2. When the polishing and removal amount of the surface layer of the steel sheet is 0.1 um or less and 5 the Ni pre-plating is not performed, or when the pre-plating weight is 0.2 g/m or less or 2 g/m , the promotion effect of the alloying is not obtained and the alloying temperature is inevitably raised. Thus, as described below, the deterioration of the hole expandability is not prevented. In order to further obtain the promotion effect of the alloying, the polishing and removal amount of the surface layer of the steel sheet is preferably set to be
10 0.5 |*m or more. [0084]
Further, in the case of manufacturing the alloyed hot-dip galvanized steel sheet, an effective Al concentration in the galvanizing bath is preferably controlled in the range of 0.05 to 0.500 mass% to control the properties of the galvanized layer. Here, the effective
15 Al concentration in the galvanizing bath is a value obtained by subtracting a Fe concentration in the galvanizing bath from the Al concentration in the galvanizing bath. [0085]
When the effective Al concentration is less than 0.05 mass%, dross significantly occurs and a good appearance cannot be obtained. On the other hand, the effective Al
20 concentration is more than 0.500 mass, the alloying is delayed and the productivity is decreased. From this reason, the upper limit of the effective Al concentration in the galvanizing bath is preferably set to be 0.500 mass%. [0086]
In order to improve the coating property and weldability, the surfaces of the
25 hot-dip galvanized steel sheet and the alloyed hot-dip galvanized steel sheet of the present invention may be subjected to upper layer plating and to a variety of treatments, for

36
example, a chromate treatment, a phosphate treatment, a lubricity-improving treatment, a weldability-improving treatment or the like. . [0087]
After the hot-dip galvanizing and the alloying-heating treatment, the rolling is 5 preferably performed for. the purpose of the final shape straightening and the loss of yield-point elongation. When the elongation percentage is less than 0.2%, the effect is not sufficient. On the other hand, when the elongation percentage exceeds 1%, the yield ratio dramatically increases and the elongation deteriorates. Therefore, the elongation percentage is preferably set to be 0.2 to 1%. In addition, before dipping into the
10 galvanizing bath, the steel sheet may be subjected to the pickling after the annealing to remove scales generated while annealing. [Example(s)] [0088]
The effects of the present invention will be now described in more detail using
15 Example. Incidentally, conditions of the examples are condition examples employed for confirming the applicability and effects of the present invention, and the present invention is not limited to these condition examples. The present invention can employ various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.
20 [0089]
A hot-dip galvanized steel sheet and an alloyed hot-dip galvanized steel sheet were manufactured under conditions indicated in Tables 2 and 3 by casting steel having compositions indicated in Table 1. First, steel slabs having each composition were heated to a slab heating temperature (°C) and then the hot rolling was finished at a finish rolling
25 temperature (°C). The obtained hot-rolled steel sheet was coiled at a coiling temperature (°C) and then was subjected to the cold rolling indicated by a cold rolling ratio (%).

37
Further, since a sheet shape is poor when the steel sheet was subjected to the cold rolling at a cold rolling ratio of 30% (cold rolling ratio less than 40%) and occurrence of scratches was concerned when the sheet subsequently passed through an annealing facility, the sheet-passing was abandoned. In addition, when the cold rolling was performed at a cold 5 rolling ratio of 80% (cold rolling ratio exceeding 70%), the rolling load became a maximum value and a predetermined sheet thickness was not obtained, so that the cold rolling at the cold rolling ratio of 80% was abandoned.
After the cold rolling, the base steel sheet was annealed at the annealing temperature (°C), was cooled (primary cooling) to a primary cooling temperature (°C) at a
10 primary cooling rate (°C/sec), and then was cooled (secondary cooling) to a cooling stop temperature(°C) at a secondary cooling rate (°C/sec). Then, the base steel sheet was held at a holding temperature (°C) for a holding time (sec).
Thereafter, the base steel sheet was cooled to 70°C or lower for the average cooling rate of 5°C/second or faster and then was rolled at a rolling ratio (elongation
15 percentage) (%). The sheet thickness was 1.4 mm. Thereafter, the surface of the base steel sheet was polished and removed up to a depth of a surface polishing quantity (urn) and then was subjected to the Ni pre-plating with the Ni pre-plating weight (g/m ).
Next, the base steel sheet was heated to the heating temperature (°C) at a temperature rising rate (°C/sec.) and then was subjected to the hot-dip galvanizing by
20 dipping into the hot-dip galvanizing bath. In addition the base steel sheet was subjected to the alloying-heating treatment for an alloying time (sec.) at the alloying temperature (°C), as necessary. Further, the speed of the jet flow (m/min) in the galvanizing bath was provided in a hot-dip galvanizing tank. In addition, the temperature of the galvanizing bath was managed to 440 to 470°C.
25 Thereafter, the base steel sheet was cooled to 70°C or lower at the average cooling
rate of 5°C/second or faster.

38
[0090]
Mechanical properties, hole expandability (X), a galvanized external appearance, an alloying degree, and plating adhesion of the obtained hot-dip galvanized steel sheet and the alloyed hot-dip galvanized steel sheet were estimated (Table 4). The mechanical 5 properties were estimated by a tensile test based on JIS Z 2241. Tensile strength (TS) and total elongation (EL) were calculated from a stress-strain curve of the tensile test. Then, TSxEL and TSxX. as an indication of workability were calculated. The hole expandability was estimated by performing a hole expanding test based on Japan Iron and Steel Federation Standard JFS T 1001 to measure a hole expanding ratio. It was determined
10 that the formability was good when the TSxEL was 17000 MPa-% or more and the TSxA, 40000 MPa-% or more. The galvanized external appearance was estimated as marks O and X by determining the presence or absence of the galvanizing faults through visual observation. Here, the mark O indicates that no galvanizing fault is present, and the mark X indicates that the galvanizing faults are present. The alloying Fe% indicates a mass%
15 of Fe contained in the galvanized layer. In the alloyed hot-dip galvanized steel sheet subjected to the alloying treatment, the content of 7 to 15% Fe indicates that the alloying has well advanced. In the hot-dip galvanized steel sheet which is not subjected to the alloying treatment, the content of Fe may be 7% or less. [0091]
20 Experiments No. a, ba, bt, c, d, e, fa, g, ha, ht, i, j, k, 1, m, n, and o are the present
invention examples in which all of the properties pass and the steel sheet of the aimed property is obtained. On the other hand, in other Experiments No., in which composition or manufacturing method is out of the range of the present invention, several properties fail to pass.
25

Steel type
No. C Si Mn P s N AI Al+Si Others
1 0.13 1.5 2.7 0.01 0.002 0.004 0.015 1.515 -
2 0.18 1.5 2.4 0.012 0.003 0.0033 0.018 1.518 -
3 0.19 2.7 1.6 0.011 0.004 0.0043 1.213 3.913 Cn0.96
4 0.18 0.1 2.5 0.013 0.0O4 0.0022 0.51 0.61 Ce:0.01,La:0.002v Vti
5 0.28 1.8 1.6 0.012 0.01 0.0022 0.576 2.376 -
6 0.27 0.6 2.4 0.01 0.0013 0.0024 1.751 2.351 MpO.0008
7 0.23 1.7 2.5 0.02 0.0023 0.0029 0.019 1.719 Ca:0.008
8 0.35 1.6 2.4 0.01 0.0014 0.0034 0.785 2.385 -
9 0.19 1.5 1.9 0.02 0.002 0.0041 0.58 2.08 TuO.03
10 0.19 1.4 1.7 0.03 0.001 0.002 0.46 1.86 B:0.001
11 0.18 1.3 1.8 0.02 0.002 0.0024 0 1.3 Mofl.l
12 0.2 1.8 2.6 0.03 0.001 0.0033 0.08 1.88 CnO.S
13 0.19 1.7 2.5 0.013 0.0015 0.0012 0.023 1.723 NM).051
14 0.21 1.5 2.4 0.006 0.0042 0.0043 0.033 1.533 TL-0.056,B:0.0053
15 0.19 1.8 1.8 0.011 0.0032 0.0027 0.016 1.816 Mo:0.33
16 0.7 2.4 2.3 0.013 0.0047 0.0039 0.032 2.432 -
17 0.18 3.4 2.5 0.014 0.0037 0.0015 0.048 3.448 -
18 0.25 2 3.5 0.014 0.0049 0.0012 0.069 2.069 Ca:0.01S
22 0.19 1.75 2.64 0.08 0.0015 0.005 2.36 4.11 Ca:0.003
23 0.35 0.1 2.4 0.08 0.0015 0.005 0.164 0.264 -
24 0.09 2.87 1.8 0.0022 0.0006 0.002 0.02 2.89 Cnl.8
25 0.11 1.7 2.9 0.0006 0.0007 0.0003 0.08 1.78 Ti-0.9
Underlnies indicate that a numeral value is out of the range of the present invention

40
[0093] [Table 2]

Experimeri No. StMl
Ijpa No. Sbbttatrg
tempcraftst
[SC1 IruihioSSog temp: (aturs
E'CJ Cc&g temperature CoHioEcg ratb [Kl temperature [CC] Pitaaiy coc&g temps ratttte Piinaiyceo&g
rate
[°C/see] Seccufaiy
cooS^iate
PC/seel Coo&igstop tenp:iatiHe Note
a 1 1230 soo SCO 50 SSO 690 1.2 120 370 Res edmTealixi steel
la 2 1230 S90 640 55 820 6*0 1.9 50 290 ftea tcA brenti-ia a teel
bb 2 1220 S90 650 55 700 670 10.7 60 3S0
be 2 1200 900 590 55 790 520 1.5 120 380 fVrfTjw rtln-j. jjeil
W 2 1180 920 620 55 800 650 orn 180 370
be 2 1200 910 570 55 810 670 1.2 8 400
bf 2 1230 930 630 55 810 740 1.8 60 370 OcmsntiiT i»w1
to 2 1200 SSO 5S0 55 820 710 1.2 50 350
Hi 2 1190 920 600 55 810 730 1.6 60 420
U 2 1210 890 590 55 800 740 1.5 50 4O0
V 2 1220 £50 580 55 820 710 17 70 380
bk 2 1210 S90 600 55 810 720 2.3 80 390
H 2 1200 970 600 55 820 710 3.S 120 390
tm 2 1230 930 600 55 820 710 3.8 ICO 400 r\vTTU™trvf steel
bo 2 1210 920 610 55 830 680 38 120 390 Ovm-plK-fljiKl
to 2 1200 900 640 55 820 6S0 4.5 60 420
bo 2 1200 SSO 530 55 820 6S0 1.2 80 70
to 2 1250 920 S» 55 830 690 1.2 80 52 OtftT" f i^"i ilttl
br 2 1240 920 580 55 820 680 1.2 SO 500
bs 2 1230 900 600 55 820 6S0 1.2 70 580
bt 2 1230 920 580 55 820 690 1.2 120 320 ftes cot hventM a teal
c 3 1210 SSO 550 57 SSO 690 3.4 SO 360 He! tut hventba steel
d 4 1230 930 500 49 850 690 1.8 70 430 ftei eat hveatka a teel
e 5 1230 950 500 60 870 690 2.9 60 400 fte s ent hventba a teel
fa 6 1230 S90 500 48 SSO 720 13.5 50 390 R< $ (pt hvtnifca s teel
lb 6 1220 S70 600 50 m SSO 2.4 100 400
fo 6 120} S90 540 50 820 m 2.4 120 400
fd 6 1190 900 490 50 SOO 650 CM 140 410 rVwrpjniTivpj^eil
fe 6 1201 930 590 50 840 670 1.6 6 390
ff 6 1230 S90 560 50 850 720 2.4 80 430
fe 6 1200 900 630 50 840 703 1.6 60 450 dvrjv "^"jlesl
ft 6 1220 960 590 50 850 720 2-2 50 370 rVv-rrwnitfv*itf>l
fi 6 1220 950 560 50 840 710 1.6 70 390 Gvmmtrveittil
fl 6 1200 920 590 50 860 690 2.S ICO 400
ft 6 1210 900 630 50 830 720 2.4 130 400
fl 6 1240 960 420 50 840 703 5.6 120 390
fin 6 I1S0 S90 550 50 850 690 2.4 93 390 Owmrrth-e itwl
fit 6 1200 900 490 50 840 710 6.2 SO 390
fo 6 1210 910 SCO 50 830 710 14 60 400
fo 6 1230 930 550 SO 810 700 14 70 70
ft 6 1210 SSO 600 SO 810 680 14 70 SQ
ft 6 1240 900 590 SO 810 680 14 60 520
fi 6 1220 910 610 50 S10 680 14 60 590
7 1250 900 600 49 830 680 10.8 70 410 ftes ect krea&a i teel
ha 8 1250 9S0 550 50 SSO 740 16.4 ICO 420 Res ecttiv-entba steel
hb g 1220 910 560 50 650 680 1.6 120 380 rVrfryw m ifvpJijej
he 8 11S0 890 600 50 840 m 1.6 ICO 380 rjwnw-ilivfti'wl
hi 8 1203 900 620 50 830 660 0.06 160 4O0
he g 1190 940 550 50 SOO 6S0 1.4 4 400
hf 8 1210 8-90 590 50 780 730 1.6 SO 380
ha g 1200 920 600 50 810 6S0 1.8 50 370 rmlartj((,„l
hh g 1190 910 570 50 830 710 14 60 410 Owminliv-mtK-l
hi S 12CO 900 580 50 860 720 2.g 190 400
hi S 1190 SSO 480 50 7SQ 740 14 ICO 390
hS; S 1200 950 550 50 810 7CO Z6 SO 390 rYvTTwm tti-p a teel
hi g 1210 920 540 50 820 710 4.g 60 3S0 Ovrrwratrvpitol
DTE1 S 1190 890 600 SO 830 70) S.g 70 360
hn s 120O 960 620 50 820 730 16 70 430
bo s 1200 930 580 SO 830 720 1.6 SO 400
to 8 1230 900 6CO 50 7S0 680 1.6 80 7J ftwru [finis 31 teel
m 13 1220 940 530 50 840 680 5.4 90 390 Pat sot iaventba i teel
n 14 1230 910 560 50 SSO 6S0 8.2 ICO 3S0 Eh! ent faveotbas teel
o 15 1240 950 600 50 £60 690 62 90 430 SYes ent men tba steel
16 1250 950 500 60 810 730 1.9 60 430 (jVYTwrcilhrnlff]
17 1230 960 600 50 7SO 7C0 1.8 120 400 rwrrvmnrve steel
t 13 1260 920 650 50 840 650 25 70 420 OVUVLtHttVfi *1£gJ
V 21 1200 S90 450 50 850 6S0 10.9 80 410 OwTTMnlB-BltK-l
w 23 1260 910 4S0 50 850 630 11.3 SO 390
X 24 1240 900 420 50 850 670 15.4 120 370
v 23. 1230 900 560 SO 850 620 13.5 100 380 Crvrjv m 1n.-flatee1
Uaier&Ks hdk-a!e that a numjrahabj s out of the rai^e of tie preset inveitba

41
[0094] [Table 3]

No. No. HoHiig t* opera hre HoBing time at
350to450=C
[««] Reaction ratb IH) Sucfsce po&hhg
quantity j>m] S*ipte-pj3tiftg Speed of pi Qswii
ga>.-enbr^ bah Temperas*
ereaignte
poke] Heafrg tempJiHurc
ra A Buying li™
w Aftjjiig
tempenbre
I'C] Note
a 1 370 150 0.4 0.15 0.21 20 12.4 435 15 47S Fre j enl mvenlba s ted
hi 2 «0 180 04 0.16 0.32 15 11.4 462 24 4S0 rteseat BveGlbasled
bb 2 3S0 173 0.6 035 1.4 10 168 495 20 450 Cc'iiMratrre a led
b; 2 380 162 02 0.7 0.9 45 25.3 437 35 505 CoaMiatrre steel
M 2 370 250 03 015 0.4 20 221 421 30 523 CKaMTBlTFe Steel
be 2 400 420 04 021 0.3 20 24.5 460 25 510 CoaMratne steel
bf 2 370 ID 02 036 0.2 25 265 463 31 545 ConMnlfFe steel
bs 2 350 240 0 0.21 0.2 35 25.3 478 24 490 CoziMnlne steel
bh 2 420 240 2J 022 0.4 20 28.4 469 19 500 CcQ7inl>7e steel
be 2 400 120 0.3 fi 1.3 20 222 458 23 510 C«3>fliilfc« steel
t* 2 3SO 150 0.2 0.15 ors 20 24.6 423 IS 520 CKzpjia&a steel
bk 2 390 240 03 012 08 4 17.6 485 20 500 CteiMiaif.e steel
H 2 390 150 02 015 1.5 20 12 427 19 540 Cpnsaiatr.-B steel
cm 2 400 150 0.3 015 1.5 25 20.5 390 15 520 cpEMiath-e sleel
to 2 390 ISO 0.4 046 1.5 20 22.4 456 130 520 CKiHjalBS sleel
to 2 420 150 03 046 1.5 20 105 450 15 625 Cm^aiatke steel
bp 2 360 150 04 022 0.4 IS 12.4 450 20 510 CraraiBlse steel
u 2 SQ 150 0.4 024 0.4 15 20.3 460 20 500 Ccc^sntlve 5 ltd
br 2 450 150 0.4 018 0.4 20 12.4 460 20 500 CorrsiBtivt sled
bs 2 520 150 04 021 0.4 20 124 450 20 J10 CraMTEtne sled
bt 2 3SO 220 03 024 224 15 14.8 510 25 J20 ft? 3 eat iaveotba steel
c 3 360 170 04 0.17 026 20 20.6 486 35 520 Ite seat faverrfi>a steel
d 4 430 120 02 026 1.24 20 168 425 21 560 Pit i est iavtolfca steel
c S 4CO 190 03 013 1.87 15 104 437 13 590 Prt seat iaveiriba steel
fa 6 390 4tO 03 024 1.44 25 165 4S0 14 490 Pit lent investfca steel
lb 6 400 500 0.4 022 0.4 30 108 4S0 20 4S0 Oaoaiatlve sleel
fc 6 400 260 03 023 0.3 15 168 470 16 490 Cczraiativ-e sleel
fd 6 410 5K> 04 016 06 10 16.8 460 24 4SO CtejMutise sleel
ft 6 390 500 03 026 0.3 15 16.8 450 30 500 CorpaiEtke sleel
ff 6 430 0 03 02 0.4 15 10.5 480 16 500 COEWntise sled
ft 6 450 m 0 016 0.3 20 168 480 24 490 Cccraietive sled
ffa 6 370 ■ 20) Li 012 0.4 15 20.4 450 30 500 CozmiBtive sled
fi 6 390 500 08 OJH 0.3 25 12.4 460 8 540 CreraiBtJve sled
8 6 400 250 0.8 016 e 20 109 450 16 510 Coa>intive sleel
ft 6 400 125 0.7 032 0.3 7. 204 460 30 490 CoiMntFie sled
n 6 390 240 0.6 018 02 20 IS 450 24 490 CmzpaiativB sleef
fin 6 390 330 09 02 0.4 45 16.8 3H 30 4S0 Cc-zpaialfce sled
fa 6 390 SCO 07 016 0.5 20 205 490 200 540
fo 6 400 330 08 0.22 05 20 30.7 500 28 650 Qsasajiiiw-e sled
fa 6 370 20} 02 0.43 022 20 10.6 520 28 500 Cl^^I^^IstsE sled
fa 6 SO 200 0.6 062 0.45 20 20.8 510 28 500 CtdMjalr.e steel
fr 6 450 2CO 0.4 026 0.25 20 25.4 500 28 490 Con*3JBtke sled
fs 6 540 20) 03 014 0.31 20 204 500 24 500 CczMntive sled
7 410 300 02 034 0.5S 30 18.4 470 30 Pre sent mveatfon sleel
ha 3 4M 260 02 016 0.24 20 19.3 459 Pre s est mveaifctfi steel
hb 3 3W 250 0.4 012 0.6 20 203 455 20 490 Ccc^siBtr*"e sled
be 3 3S0 260 0.3 0.18 0.3 15 19.6 460 30 500 Cozmntrve sled
hd 8 400 m 1 022 0.4 30 14.5 470 20 510 Cwrantr.-f steel
bs ■ 3 400 470 0.4 018 03 25 20.5 4S0 2S 520 CosMrath"e steel
hf 8 3S0 0 0.9 024 0.3 25 10.8 455 24 490 ConMratX-f steel
te 3 370 190 0 024 0.4 20 15.6 4S0 20 4S0 Cora>uath"f steel
hh 8 410 320 22 016 03 15 168 500 24 490 CrcaMiat&e steel
bi 3 400 450 0.8 0J6 0.4 30 30.8 460 45 500 CtoMialfc'e steel
hi S 390 260 07 018 0.05 40 20.4 460 20 510 CKsearaiive sleel
He s 390 ISO 0.8 0.24 0.4 5 18.6 480 30 480 cp3EEjiBit.-e sleel
hi 8 3S0 220 05 016 0.8 20 0_8 500 20 470 Cc-rP!iitiv5 steel
bra 8 m ISO 0.6 012 1.6 50 18.2 m 24 450 Oaajelive steel
hn 8 430 460 0.8 016 0.8 25 203 460 200 510 Cososjatirs steel
bo 8 400 2S0 03 016 0.6 10 268 480 30 630 CCd%aiKtive s ted
bo 8 350 330 0.4 022 0.4 15 108 470 30 450 Crc^siEtfce steel
ho 8 SO 330 05 014 03 20 205 450 24 4S0 0>xr^iatF*"e sleel
he 8 450 330 0.4 032 0.2 15 14.6 470 45 450 Coz3HislF*"e steel
hs 8 550 330 0.3 0.28 0.6 20 14.9 460 30 4S0 CccwiHtr*"e sled
ht 8 380 640 0.4 062 0.2 30 168 460 30 510 Pre Stat fciveotKKi steel
i 9 410 180 0.4 015 0.32 20 11.4 460 24 4S0 Preltot nveoSn st»l
10 400 190 0.2 019 0.22 20 25.5 450 35 490 PteseotiiVHiiEn steel
k 11 400 250 03 0 26 059 20 36.5 455 21 550 Pre seot BiVeotija steel
] 12 390 280 0.5 024 l.S 20 19.7 449 - Pre! sot hveEtjja steel
m 13 390 SOO 0.4 0.18 023 20 208 460 - Present iiveotSj-a steel
n 14 380 260 0.3 0.11 0.33 20 88 450 16 530 Present inveQt»a steel
o IS 430 300 0.6 0.06 0.27 20 309 455 9 Present frivectsa steel
1* 430 120 0.3 016 3.55 40 106 462 15 450 0>zr*3JBtiv"e s ted
17 400 130 0.4 024 1.24 20 108 435 16 479 CcaMJBtke s led
r is 420 250 0.S 052 1.5 20 125 458 17 510 CcawratK-e s led
V n 410 250 02 0.12 024 10 10.8 428 30 490 Cccpantpe steel
XT 23 390 260 0.7 012 026 15 15.5 437 25 475 Cozparatpe steel
X 24 370 200 06 0.15 035 25 18.6 461 19 4S0 CcCHMiatfre steal
V 25 350 120 04 015 0.45 30 14.6 478 Ccj^antp* S!M1
UofetSres fcjJsate tint a iuiKialralie is a* of tbi range of the peKEt imndbn

42
[0095] [Table 4]

Etperi ffieci No. [ii] Marte&sie ©
(HI Muttn'Si © IK] Muter* ie © Marti sis IK1 ResiJjal aciSenie
mi Fenle
m [K] TS[MPo] £L[K] >{%*) TSiEL ISsX GikiGiad external Albjiig
mi Note
a 47 14 3 0 64 g 23 0 937 23 59 22701 5S233 O 7.8 fttsesifatBsfoi sleel
ba 32 4 4 3 43 9 33 10 1013 25 48 25325 4S624 O 10.4 Yn s ea I Torait&a a Seel
ib 0 0 fl 0 0 0 100 0 683 21 67 14343 45761 O 10.5 Q>3¥>?.rar*e*!^
bo 23 0 0 a 23 0 62 15 743 18 29 13374 21547 O 11.1
W 23 0 0 o 23 0 55 n 7S9 15 25 11835 19725 O 11.9
ba 38 0 0 0 33 0 49 13 824 16 29 13134 23S96 O 11.2
bf 11 33 14 2 60 2 3S 0 1139 11 24 12529 27336 O 10.9
bfj 35 10 0 0 45 16 39 0 1037 26 24 26962 24*88 O 8.9
ih 34 6 12 0 52 3 37 8 923 16 55 I476S 50765 O 9-3 rwnwrafirt steel
U 40 6 4 3 53 S 39 0 9S4 25 45 24600 442S0 * 11.3
H 38 5 4 3 50 9 41 0 9S9 23 43 22747 42527 « 11.5 riYipttfliircfiv.1
bk 40 J 4 3 52 10 33 0 982 23 51 225S6 50082 x 9.4
H 41 5 4 2 52 8 39 1 931 21 41 20601 40221 X 123
tm 43 4 5 3 55 9 36 0 9S9 23 44 22747 43516 X 11.9
to 40 4 4 0 43 4 37 11 923 14 51 12922 47073 0 13.9 Ccaitfnlif e steel
to 38 5 0 0 43 0 39 18 SS6 13 39 15943 34554 0 163
tp 8 52 0 0 60 0 « 0 1033 11 23 11363 2375? 0 10.7 rnnr„rK^f Up]
tq 7 55 S 0 62 2 JS 0 1073 9 32 9702 34496 0 10.2 OmtiiSfci steel
br 33 5 0 0 33 0 39 23 83.4 17 42 14173 3J028 0 9.9
bs 22 0 0 0 22 0 46 32 753 16 46 120+3 34638 0 10.6
M 29 10 7 6 52 9 39 0 1P0I 22 65 22022 65065 0 128 Fst'eat fai eafra sted
G 53 6 3 3 65 11 24 0 nos 21 49 23263 54292 0 11.6 Fit !Ent ETSLOKI I Mel
d J5 S 4 0 67 10 23 0 1239 20 45 247S9 55755 0 12.4 Present raTetba steal
e 43 s 7 3 66 13 21 0 1249 16 30 199S4 37470 0 8.7 Ttttat fai tsfea ttte-1
fa 4i 11 11 9 76 14 10 0 12S9 16 32 2O4S0 40960 0 7.9 Pres eat hTQfca 1 teel
ft D 0 0 e 0 0 ICO 0 ZU 20 72 14240 51264 0 8.6
ft 23 0 0 0 23 0 54 13 m 19 42 14725 32550 0 8.8
fd 24 0 0 O 24 0 49 27 793 17 33 13431 30134 0 83
fe 42 0 0 0 42 0 33 25 843 15 32 12645 26976 0 9.5
ff 10 65 3 0 73 4 IS 0 1293 9 24 11682 31152 0 9.7
ft 47 11 0 0 5S 23 19 0 1345 15 14 20175 1SS30 0 8.9
ft 45 11 27 0 83 2 15 0 1019 8 40 8152 40760 0 11.3
fi 42 12 9 6 69 12 19 0 1216 15 35 18240 42560 « 121 refT\!/stoeilMl
H 43 11 9 6 69 13 18 0 1224 14 40 17136 48960 X 11.4
ft 44 11 10 0 65 14 11 10 1265 13 33 16445 41745 , 10.9
fl 41 12 11 6 70 11 19 0 1274 16 34 20384 43316 x 9.6
fkn 42 12 12 5 71 12 17 0 1293 15 38 19395 49134 X 9.7 CnauailiteshHiT
ft 41 13 8 6 63 0 16 16 SOS IS 41 14490 33005 0 14.7
ft 41 11 0 0 52 0 16 32 785 19 42 14915 32970 0 17.2 Cc-ara^tnesleel
fp 11 58 0 0 69 3 23 0 1352 7 9 9464 12163 0 9.2 Olai»-sIiifit(?l
ft 9 60 Q 0 69 1 30 0 1397 6 4 8382 55S3 0 9.6
ft 39 0 0 0 39 a 33 23 821 17 30 13957 2+630 0 9.6 CrrTi?jslraesli^l
fs 23 0 0 0 23 0 40 32 782 IS 24 14076 1S76S 0 9.9 OKiiwtfwihwl
49 11 6 0 66 12 22 0 1021 24 51 24504 52071 0 28 Fr?9Qlhreatj>nslKl
U J2 13 10 7 82 13 0 0 1450 14 31 20300 44950 0 2.7 freseataiectixi steel
ib 0 0 0 O 0 0 100 0 759 20 59 15160 44781 0 9.6
he 26 0 0 0 26 0 37 37 824 18 37 14832 30483 0 10.2
hd 19 0 0 0 19 S 34 47 793 16 32 126S3 25376 0 10.5 C&aiwaise steel
he 37 0 0 0 37 0 32 31 852 13 30 11141 25710 0 10.9
hf 0 55 12 0 67 IS 18 0 1652 4 7 66C8 11564 0 9.9
1* 34 . 15 0 a 49 29 22 0 1523 13 7 19799 10661 0 9.8
hh 52 14 29 0 95 5 0 0 1221 10 36 12210 43956 0 10.2 OMTLKaiie steel
hi 54 11 9 8 82 18 0 0 1434 13 32 18642 45S83 X 11.4
H 42 11 8 6 67 15 13 0 1426 13 33 1853S 47058 x 10.7 G>:o>2.-itfce steel
ii 53 13 11 8 85 15 0 0 1462 14 34 20468 49703 X 10 OBiw*f ii«a
n J2 12 10 8 82 18 0 0 14S9 14 31 20846 46159 > 8.6 Ovnv**lfcT,tlrt
tm J5 14 10 6 85 15 0 0 1432 13 38 19266 56316 X 81 rotmtntite steel
ha 62 13 11 9 95 5 0 0 1162 11 29 12732 33693 0 13.8
to 51 24 0 0 76 0 0 24 1123 7 32 7375 36000 0 168
hp 12 61 0 0 73 3 24 0 ISS9 6 4 9534 6356 0 10.1
ha 13 60 0 0 73 0 27 0 1601 5 1 S»5 1641 0 9.7 Cttiraiilfce *teel
ht 35 7 0 0 42 0 39 19 923 16 28 14768 25844 0 11.9
hs 33 0 0 a 33 0 43 24 835 16 25 14160 22125 0 9,9 OxrrautBi steel
ht 20 21 6 4 51 21 23 0 1356 15 35 20340 47460 0 10.3 Frss ent biFai&a steel
I 52 4 4 3 63 10 27 0 1185 17 45 20145 53325 0 10.4 Present faveitixi steel
i Jl 9 4 0 64 10 26 0 1205 16 46 19280 55430 0 11.6 ftescnt in* en tin steel
k 54 4 3 4 65 9 26 0 9S9 23 50 22747 49450 0 124 ftesent fai eatbo steel
1 50 S 4 4 66 8 26 0 1201 17 35 20417 42035 0 27 Fres sit hpslrai steel
m 55 5 3 4 67 9 24 0 1186 19 39 22534 46254 0 1.6 Present fateatira steel
B 44 S 6 5 63 10 27 0 120S 17 34 20536 41072 0 11.6 Pas ent fai esti™ steel
o 51 6 7 7 71 9 20 0 1226 16 36 19616 44136 0 1.7 Presen t inTSL&a steel
0 63 22 0 85 15 0 0 1950 5 3 2ZK 5S50 0 10.5
16 5 5 3 29 10 61 0 24i 18 26 17010 24570 X 6.3
i 10 75 13 a 9S 2 0 0 1523 9 29 13707 44167 0 8.9
V 16 0 0 o 16 13 71 0 894 17 24 1519S 21456 0 10.7 CMiMntite steel
w 92 8 0 0 100 0 0 0 927 11 62 10197 57474 0 125
X 62 21 11 3 97 3 0 0 862 18 24 15516 206SS 0 11.3
r 5 0 0 a 5 0 95 0 1342 7 16 9394 21472 0 2.1 CKapHtiBe steel
Urdirfeei fcdijte thit arpumtalvabe fc cut of (a tanje of ihe pieHd hmtin

43
[Industrial Applicability] [0096]
The present invention provides the high-strength galvanized steel sheet having
excellent formability with the ultimate tensile strength of 980 MPa or more, which is
5 suitable for the structural member, the reinforcing member, and the suspension member of
automobiles. Accordingly, the present invention can be expected to greatly contribute to
the lighter-weight of automobiles and is extremely high in effect in industry.

44

[Name of Document] CLAIMS [Claim 1]
A high-strength hot-dip galvanized steel sheet having excellent plating adhesion, formability, and hole expandability with an ultimate tensile strength of 980 MPa or more, 5 the hot-dip galvanized steel sheet comprising a hot-dip galvanized layer formed on a surface of a base steel sheet,
wherein the base steel sheet contains: by mass%,
C: 0.05% to 0.4%;
Si: 0.01% to 3.0%;
10 Mn: 0.1% to 3.0%;
Al: 0.01 to 2.0%; in which Si + Al > 0.5%
P: limited to 0.04% or less;
S: limited to 0.05% or less;
N: limited to 0.01% or less; and
15 a balance including Fe and inevitable impurities,
a micro structure of the base steel sheet contains 40% or more by total volume
fraction of martensite and bainite, 8% or more by volume fraction of residual austenite, and
a balance of the microstructure being ferrite or ferrite and 10% or less by volume fraction
ofpearlite,
20 the martensite contains 10% or more by total volume fraction of two or more
kinds of three kinds of martensites (1), (2), and (3) below, and
the hot-dip galvanized layer contains less than 7 mass% of Fe,
the martensite (1): C concentration (when there is a cementite precipitation, also including C in cementite); CMl is less than 0.8 mass%, and nano-indentation test hardness 25 Hitl satisfies Expression 1.
Hitl/{-982.1 x (CMl)2 + 1676 x CMl + 189} < 0.50 - Expression 1

45
the martensite (2): C concentration (when there is a cementite precipitation, also including C in cementite); CM2 is 0.8 mass% or more, and nano-indentation test hardness Hit2 satisfies Expression 2.
Hit2/{-982.1 x (CM2)2 + 1676 x CM2 + 189} < 0.50 - Expression 2
5 the martensite (3): C concentration (when there is a cementite precipitation, also
including C in cementite); CM3 is 0.8 mass% or more, and nano-indentation test hardness Hit3 satisfies Expression 3.
0.5 < Hit3/{-982.1 x (CM3)2 + 1676 x CM3 + 189} < 0.80 - Expression 3
10 [Claim 2]
The high-strength hot-dip galvanized steel sheet having the excellent plating
adhesion, formabihty, and hole expandability with the ultimate tensile strength of 980 MPa
or more according to claim 1, wherein the base steel sheet further contains one or two or
more of: by mass%,
15 Cr: 0.05 to 1.0%;
Mo: 0.05 to 1.0%; Ni: 0.05 to 1.0%; and Cu: 0.05 to 1.0%.
20 [Claim 3]
The high-strength hot-dip galvanized steel sheet having the excellent plating
adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa
or more according to claim 1, wherein the base steel sheet further contains one or two or
more of: by mass%,
25 Nb: 0.005 to 0.3%;
Ti: 0.005 to 0.3%; and

46
V: 0.01 to 0.5%.
[Claim 4]
The high-strength hot-dip galvanized steel sheet having the excellent plating 5 adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to claim 1, wherein the base steel sheet further contains B: 0.0001 to 0.1%bymass%.
[Claim 5]
10 The high-strength hot-dip galvanized steel sheet having the excellent plating
adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to claim 1, wherein the base steel sheet further contains one or two or more of: by mass%,
Ca: 0.0005 to 0.01%;
15 Mg: 0.0005 to 0.01%; and
REM: 0.0005 to 0.01%.
[Claim 6]
A high-strength alloyed hot-dip galvanized steel sheet having excellent plating
20 adhesion, formability, and hole expandability with an ultimate tensile strength of 980 MPa
or more, the alloyed hot-dip galvanized steel sheet comprising an alloyed hot-dip
galvanized layer formed on a surface of a base steel sheet,
wherein the base steel sheet contains: by mass%,
C: 0.05% to 0.4%;
25 Si: 0.01% to 3.0%;
Mn: 0.1% to 3.0%;

47
Al: 0.01 to 2.0%; in which Si + Al > 0.5%
P: limited to 0.04% or less;
S: limited to 0.05% or less;
N: limited to 0.01% or less; and
5 a balance including Fe and inevitable impurities,
a microstructure of the base steel sheet contains 40% or more by total volume
fraction of martensite and bainite, 8% or more by volume fraction of residual austenite, and
a balance of the microstructure being ferrite or ferrite and 10% or less by volume fraction
ofpearlite,
10 the martensite contains 10% or more by total volume fraction of two or more
kinds of three kinds of martensites (1), (2), and (3) below, and
the alloyed hot-dip galvanized layer contains 7 to 15 mass% of Fe,
the martensite (1): C concentration (when there is a cementite precipitation, also including C in cementite); CM1 is less than 0.8 mass%, and nano-indentation test hardness 15 Hitl satisfies Expression 1.
Hitl/{-982.1 x (CM1)2 + 1676 x CM1 + 189} < 0.50 - Expression 1
the martensite (2): C concentration (when there is a cementite precipitation, also
including C in cementite); CM2 is 0.8 mass% or more, and nano-indentation test hardness
Hit2 satisfies Expression 2.
20 Hit2/{-982.1 x (CM2)2 + 1676 x CM2 + 189} < 0.50 - Expression 2
the martensite (3): C concentration (when there is a cementite precipitation, also including C in cementite); CM3 is 0.8 mass% or more, and nano-indentation test hardness Hit3 satisfies Expression 3.
0.5 < Hit3/{-982.1 x (CM3)2 + 1676 x CM3 + 189} < 0.80 ■» Expression 3 25
[Claim 7]

48
The high-strength alloyed hot-dip galvanized steel sheet having the excellent
plating adhesion, formability, and hole expandability with the ultimate tensile strength of
980 MPa or more according to claim 6, wherein the base steel sheet further contains one or
two or more of: by mass%,
5 Cr: 0.05 to 1.0%;
Mo: 0.05 to 1.0%;
Ni: 0.05 to 1.0%; and
Cu: 0.05 to 1.0%.
10 [Claim 8]
The high-strength alloyed hot-dip galvanized steel sheet having the excellent
plating adhesion, formability, and hole expandability with the ultimate tensile strength of
980 MPa or more according to claim 6, wherein the base steel sheet further contains one or
two or more of: by mass%,
15 Nb: 0.005 to 0.3%;
Ti; 0.005 to 0.3%; and V: 0.01 to 0.5%.
[Claim 9]
20 The high-strength alloyed hot-dip galvanized steel sheet having the excellent
plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to claim 6, wherein the base steel sheet further contains B: 0.0001 to 0.1% by mass%.
25 [Claim 10]
The high-strength alloyed hot-dip galvanized steel sheet having the excellent

49
plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to claim 6, wherein the base steel sheet further contains one or two or more of: by mass%,
Ca: 0.0005 to 0.01%;
5 Mg: 0.0005 to 0.01%; and
REM: 0.0005 to 0.01%.
[Claim II]
A manufacturing method of a high-strength hot-dip galvanized steel sheet having
10 excellent plating adhesion, formability, and hole expandability with an ultimate tensile
strength of 980 MPa or more, the manufacturing method comprising:
with respect to a steel billet containing: by mass%,
C: 0.05% to 0.4%;
Si: 0.01% to 3.0%;
15 Mn: 0.1% to 3.0%;
Al: 0.01 to 2.0%; in which Si + Al > 0.5%
P: limited to 0.04% or less;
S: limited to 0.05% or less;
N: limited to 0.01% or less; and
20 a balance including Fe and inevitable impurities,
heating to 1200°C or higher and performing hot rolling at an Ar3 transformation temperature or higher;
performing cold rolling on a base steel sheet after the hot rolling at a reduction
ratioof40to70%;
25 annealing the base steel sheet after the cold rolling at 730 to 900°C;
cooling the base steel sheet after the annealing to a temperature of 650 to 750°C at

50
an average cooling rate of 0.1 to 200°C/second, and cooling the base steel sheet to 450°C or lower from the temperature of 650 to 750°C at an average cooling rate of 20°C/second or faster;
holding the base steel sheet cooled to the 450°C or lower in a range of 350 to 5 450°C for 120 seconds or longer;
cooling the base steel sheet held in the range of 350 to 450°C to 70°C or lower at an average cooling rate of 5°C/second or faster;
rolling the base steel sheet cooled to the room temperature at an elongation
percentage of 0.2 to 2%;
10 heating the rolled base steel sheet to "temperature of hot-dip galvanizing bath -
40"°C to "temperature of hot-dip galvanizing bath + 50"°C at an average temperature rising rate of 10°C/second or faster;
dipping and hot-dip galvanizing the base steel sheet heated to the "temperature of hot-dip galvanizing bath - 40"°C to "temperature of hot-dip galvanizing bath + 50"°C into 15 a hot-dip galvanizing bath; and
cooling the hot-dip galvanized steel sheet, which is hot-dip galvanized, to 70°C or lower at an average cooling rate of 5°C/second or faster.
[Claim 12]
20 The manufacturing method of the high-strength hot-dip galvanized steel sheet
having the excellent plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to claim 11, wherein a hot-dip galvanizing bath flows at a flow rate of 10 m/min or more and 50 m/min or less at the time of the hot-dip galvanizing.
25
[Claim 13]

51
The manufacturing method of the high-strength hot-dip galvanized steel sheet having the excellent plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to claim 11, wherein before being heated to the "temperature of hot-dip galvanizing bath - 40"°C to "temperature of hot-dip 5 galvanizing bath + 50"°C, the base steel sheet is subjected to pickling, and then a surface of the base steel sheet is polished and removed to a depth of 0.1 urn or more and is pre-plated with 0.2 to 2g/m2 of Ni.
[Claim 14]
10 A manufacturing method of a high-strength alloyed hot-dip galvanized steel sheet
having excellent plating adhesion, formability, and hole expandability with an ultimate
tensile strength of 980 MPa or more, the manufacturing method comprising:
with respect to a steel billet containing: by mass%,
C: 0.05% to 0.4%;
15 Si: 0.01% to 3.0%;
Mn: 0.1% to 3.0%;
Al: 0.01 to 2.0%; in which Si + Al > 0.5%
P: limited to 0.04% or less;
S: limited to 0.05% or less;
20 N: limited to 0.01% or less; and
a balance including Fe and inevitable impurities,
heating to 1200°C or higher and performing hot rolling at an Ar3 transformation temperature or higher;
performing cold rolling on a base steel sheet after the hot rolling at a reduction 25 ratioof40to70%;
annealing the base steel sheet after the cold rolling at 730 to 900°C;

52
cooling the base steel sheet after the annealing to a temperature of 650 to 750°C at
an average cooling rate of 0.1 to 200°C/second, and cooling the base steel sheet to 450°C
or lower from the temperature of 650 to 750°C at an average cooling rate of 20°C/second
or faster;
5 holding the base steel sheet cooled to the 450°C or lower in a range of 350 to
450°C for 120 seconds or longer;
cooling the base steel sheet held in the range of 350 to 450°C to 70°C or lower at an average cooling rate of 5°C/second or faster;
rolling the base steel sheet cooled to the room temperature at an elongation 10 percentage of 0.2 to 2%;
heating the rolled base steel sheet to "temperature of hot-dip galvanizing bath -40"°C to "temperature of hot-dip galvanizing bath + 50"°C at an average temperature rising rate of 10°C/second or faster;
dipping and hot-dip galvanizing the base steel sheet heated to the "temperature of 15 hot-dip galvanizing bath - 40"°C to "temperature of hot-dip galvanizing bath + 50"°C into a hot-dip galvanizing bath and performing alloying-heating treatment at "temperature of hot-dip galvanizing bath - 40"°C or higher and 560°C or lower within 40 seconds; and
cooling the alloyed hot-dip galvanized steel sheet, which is subjected to the alloying-heating treatment, to 70°C or lower at an average cooling rate of 5°C/second or 20 faster.
[Claim 15]
The manufacturing method of the high-strength alloyed hot-dip galvanized steel
sheet having the excellent plating adhesion, formability, and hole expandability with the
25 ultimate tensile strength of 980 MPa or more according to claim 14, wherein a hot-dip
galvanizing bath flows at a flow rate of 10 m/min or more and 50 m/min or less at the time

53
of the hot-dip galvanizing.
[Claim 16]
The'manufacturing method of the high-strength alloyed hot-dip galvanized steel
5 sheet having the excellent plating adhesion, formability, and hole expandability with the ultimate tensile strength of 980 MPa or more according to claim 14, wherein before being heated to the "temperature of hot-dip galvanizing bath - 40"°C to "temperature of hot-dip galvanizing bath + 50"°C, the base steel sheet is subjected to pickling, and then a surface of the base steel sheet is polished and removed to a depth of 0.1 um or more and is
0 pre-plated with 0.2 to 2g/m2 of Ni.
Dated this 22.04.2014
[RANJNA MEHTA-DUTT]
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT^]