DESCRIPTION
TITLE OF INVENTION: METHOD OF MANUFACTURING NONORIENTED
ELECTRICAL STEEL SHEET
TECHNICAL FIELD
[0001] The present invention relates to a method of
manufacturing a non-oriented electrical steel sheet
suitable for an iron core of a rotary machine or the
like.
BACKGROUND ART
[0002] In manufacturing a non-oriented electrical
steel sheet, hot rolling on a slab and so on are
performed. Various suggestions on a method of
manufacturing a non-oriented electrical steel sheet
have been conventionally offered (Japanese Laid-open
Patent Publication No. 2009-248108, Japanese Laidopen
Patent Publication No. 2004-332031).
[0003] However, when a non-oriented electrical steel
sheet is manufactured by a conventional method, small
irregularities occur at both edges, in the width
direction of a hot-rolled steel sheet obtained by the
hot rolling if a composition of a slab is of a nontransformed
type (e-single phase type), and edge
cracks are generated from the irregularities. For
this reason, trimming is performed after the hot
rolling. With a larger amount of trimming, the yield
decreases more.
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0004] An object of the present invention is to
provide a method of manufacturing a non-oriented
electrical steel sheet capable of improving the
yield.
SOLUTION TO PROBLEM
[0005] The summary of the present invention is as
follows.
[000'6]
(1) A method of manufacturing a non-oriented
electrical steel sheet, including:
heating a silicon steel material at a temperature
not lower than 1000°C nor higher than 1200°C;
hot rolling the heated silicon steel material
obtain a steel strip;
cold rolling the steel strip; and
then finish annealing the steel strip,
wherein the silicon steel material contains, by
mass%,
C: not less than 0.0001% nor more than 0.005%;
Si: not less than 1.0% nor more than 4.0%;
Al: not less than 0. 2% nor more than 3.0%;
Mn: not less than 0.2% nor more than 1.5%;
P: not less than 0.001% nor more than 0.1%;
S: not less than 0.0001% nor more than 0.0050%;
Ti: not less than 0.0001% nor more than 0.0030%;
and
not less than 0.0010% nor more than 0.0030%;
and
a balance being composed of Fe and inevitable
impurities,
wherein where a Si content (mass%), an Al content
(mass%), and a Mn content (masso) are expressed by
[Si], [Al], [Mn] respectively, a relation of
"[Si]+2x[Al]-[Mn]?2.0" is established, and
wherein a finish temperature of rough rolling of
the hot rolling is set to not lower than 800°C nor
higher than 1100°C.
[0007]
(2) The method of manufacturing a non-oriented
electrical steel sheet according to (1), wherein the
finish temperature of the rough rolling of the hot
rolling is set to not lower than 900°C nor higher than
1080°C.
[0008]
(3) The method of manufacturing a non-oriented
electrical steel sheet according to (1), wherein the
finish temperature of the rough rolling of the hot
rolling is set to not lower than 950°C nor higher than
1060°C.
[0009]
(4) The method of manufacturing a non-oriented
electrical steel sheet according to any one of (1) to
(3), wherein the heating of the silicon steel
material before the hot rolling is performed in a
range of not lower than 1040°C nor higher than 1200°C.
[0010]
(5) The method of manufacturing a non-oriented
electrical steel sheet according to any one of (1) to
(3), wherein the heating of the silicon steel
material before the hot rolling is performed in a
range of not lower than 1060°C nor higher than 1180°C.
[0011]
(6) The method of, manufacturing a non-oriented
electrical steel sheet according to any one of (1) to
(5), wherein a N content in the silicon steel
material is not less than 0.0010% nor higher than
0.00250.
ADVANTAGEOUS EFFECTS OF INVENTION
[0012] According to the present invention, the
condition of heating the silicon steel material and
the condition of the rough rolling of the hot rolling
are appropriately defined, so that the edge cracks in
the width direction occurring in the hot rolling can
be significantly suppressed.
DESCRIPTION OF EMBODIMENTS
[0013] In a method of manufacturing a non-oriented
electrical steel sheet according to an embodiment of
the present invention, heating (slab heating) is
performed on a silicon steel material (slab) with a
predetermined composition at a temperature not lower
than 1000°C nor higher than 1200°C, and hot rolling is
performed on the heated silicon steel material to
obtain a steel strip. Next, annealing (hot-rolled
steel sheet annealing) is performed on the steel
strip as necessary, and then cold rolling is
performed on the steel strip. Subsequently, finish
annealing is performed on.the steel strip.
[0014] The silicon steel material contains, for
example, by mass%, C: not less than 0.0001% nor more
than 0.005%, Si: not less than 1.0% nor more than
4.0%, Al: not less than 0.2% nor more than 3.0%, Mn:
not less than 0.2% no.r more than 1,5%, P,: not less
than'0.001% nor more than 0.1%, S: not less than
0.0001% nor more than 0.0050%, Ti: not less than
0.0001% nor more than 0.0030%, and N: not less than
0.0010% nor more than 0.0030%, and a balance being
composed of Fe and inevitable impurities. Further,
where the Si content (mass%), the Al content (mass%),
and the Mn content (mass%) are expressed by [Si],
[Al], [Mn] respectively, a relation of " [Si] +2x [Al] -
[Mn]?2.0" is established. Hereinafter, the reasons
to limit them will be described. In the following
descript-ion, % means mass%.
[0015] C (carbon) forms TiC in a non-oriented
electrical steel sheet to deteriorate the magnetic
property. Further, precipitation of C makes magnetic
aging remarkable. This phenomenon is prominent when
the C content is over 0.005%. On the other hand, it
takes huge cost to perform decarburization to the C
content of less than 0.0001%. Accordingly, the C
- 5 -
content is set to not less than 0.0001% nor more than
0.005 .
[0016] Si (silicon ) reduces the core loss. When the
Si content is less than 1.0%, this effect is
insufficient . On the other hand, when the Si content
is over 4.0%, the cold rolling is difficult to
perform. Accordingly, the Si content is set to not
less than 1.0% nor more than 4.0%.
[0017] Al ( aluminum) reduces the core loss as with
Si. When the Al content is less than 0.2 %, this
effect is insufficient. On the other hand, when the
Al content is over 3 . 0%, the cost is significantly
high . Accordingly, the Al content is set to not less
than 0 . 2% nor more than 3.0%.
[0018] Mn ( manganese ) increases the hardness of a
non-oriented electrical steel sheet to improve the
punching property . When the Mn content is less than
0.2%, this effect is insufficient . On the other
hand , when the Mn content is over 1 . 5%, the cost is
significantly high. Accordingly, the Mn content is
set to not less than 0.2% nor more than 1.5%.
[0019] -P (phosphorus) increases the strength of a
non-oriented electrical steel sheet to improve the
workability. When the P content is less than 0.001%,
this effect is insufficient. On the other hand, when
the P content is over 0.1%, the cold rolling is
difficult to perform. Accordingly, the P content is
set to not less than 0.001% nor more than 0.1%.
[0020] S (sulfur) forms sulfides such as TiS and
- 6 -
MnS. These sulfides prevent growth of crystal grains
and deteriorate the core loss. This phenomenon is
prominent when the S content is over 0.0050%. On the
other hand, it takes huge cost to perform
desulfurization to the S content of less than
0.0001%. Accordingly, the S content is set to not
less than 0.0001% nor more than 0.0050%.
[0021] Ti (titanium) forms Ti precipitates such as
TiN, TiS, and TiC to inhibit growth-of crystal grains
and deteriorate the core loss. This phenomenon is
prominent when the Ti content is over 0.0030%. On
the other hand, it takes huge cost to reduce the Ti
content to less than 0.0001%. Accordingly, the Ti
content is set to not less than 0.0001% nor more than
0.0030%.
[0022] N (nitrogen) forms a nitride such as TiN to
deteriorate the core loss. This phenomenon is
prominent when the N content is over 0.0030%. On the
other hand, when the N content is less than 0.001.0%,
the crystal grains excessively coarsen during the
slab heating to decrease the density of the grain
boundary', resulting in easy occurrence of cracks at
the end portions in the width direction during the
hot rolling. Accordingly, the N content is set to
not less than 0.0010% nor more than 0.0030 %.
Further, the N content is preferably not less than
0.0010% nor more than 0.0025%.
[0023] Si and Al are ferrite formers, whereas Mn is
an austenite former. When the relation of
"[Si]+2x[Al]-[Mn]^2.0" is established, the
composition of the silicon steel material is a
composition of non-transformed type (n-single phase
type). In this case, the temperature of the steel
sheet can be made higher in the hot-rolled steel
sheet annealing subsequent to the hot rolling and in
the finish annealing performed after the cold rolling
subsequent thereto. Accordingly, a magnetic property
better than that when the composition causing
transformation is employed. Note that if the
relation of "[Si]+2x[Al]-[Mn]?2.0" is not satisfied,
the composition of the silicon steel material is a
composition of an n-y transformed type, in which the
crystal structure thus changes in the transformation
and edge cracks as many as in the non-transformed
type hardly occur.
[0024] Note that the silicon steel material may
contain Cu. Cu improves the corrosion resistance of
a non-oriented electrical steel sheet and incre,-uses
the specific resistance thereof to improve the core
.loss. When the Cu content is less than 0.0001%, this
effect is insufficient. On the other hand, the Cu
content is over 0.2%, a scab or the like is likely to
occur on the surface of a non-oriented electrical
steel sheet to deteriorate the surface quality.
Accordingly, the Cu content is preferably set to not
less than 0.0001% nor more than 0.2%.
[0025] As described above, the S, Ti and N contents
in the silicon steel material used in this embodiment
8 -
are relatively low. For this reason, the
precipitates slightly occur and the crystal grains
easily grow in the heating of the silicon steel
material (slab heating) and in the rough rolling.
Hence, the temperature conditions for them are
appropriately defined in this embodiment as described
below.
[0026] As described' above, the silicon steel
material is heated at a temperature not lower than
1000°C nor higher than 1200°C before the hot rolling
in this embodiment. If this temperature is lower
than 1000°C, the heating is insufficient, leading to a
difficulty to perform the hot rolling subsequent
thereto. On the other hand, if the silicon steel
material is heated at over 1200°C, the crystal grains
excessively coarsen to decrease the density of the
grain boundary at both edges in the width direction
of the silicon steel material, resulting in easy
occurrence of an edge crack in the width direction
during the hot rolling. Accordingly, the temperature
of the heating before the hot rolling is set to not
lower than 1000°C nor higher than 1200°C. Further,
this temperature is preferably set to not lower than
1040°C nor higher than 1200°C, and more preferably to
not lower than 1060°C nor higher than 1180°C.
[0027] Further, the finish temperature of the rough
rolling of the hot rolling is set to not lower than
800°C nor higher than 1100°C. The finish temperature
of the rough rolling here means an extracting side
temperature of a final pass of the rough rolling. If
the finish temperature of the rough rolling is lower
than 800°C, the temperature of the finish rolling is
to be 700°C level, so that the rolling load is too
large, resulting in a difficulty in operation. On
the other hand, if the finish temperature of the
rough rolling is over 1100°C, the crystal grains
easily deform to spread in the width direction at
both edges in the width direction during the rolling
and, as a result, the edge crack in the width
direction is large. Accordingly,, the finish
temperature of the rough rolling is set to not lower
than 800°C nor higher than 1100°C. Further, this
finish temperature is preferably set to not lower
than 900°C nor higher than 1080°C, and more preferably
to not lower than 950°C nor higher than 1060°C.
[0028] Note that the silicon steel material (slab)
may be manufactured in a manner that, for example,
steel is melted in a converter, an electric furnace,
or the like, and the molten steel is subjected to a
vacuum degassing treatment as necessary, and next is
subjected to continuous casting. Further, the
silicon steel material may also be manufactured by
performing bloom rolling after making an ingot in
place of the continuous casting.- The thickness of
the silicon steel material is set to, for example,
150 mm to 350 mm, and preferably to 220 mm to 280 mm
[EXAMPLES]
[0029] Next, experiments conducted by the present
- 10
inventors will be explained. Conditions and so on in
these experiments are examples employed for
confirming the operability and effect of the present
invention, and the present invention is not limited
to these examples.
[0030]
(EXAMPLE 1)
Steel ingots (silicon steel materials) each
containing, by mass%, C: 0.0021%, Si: 3.00, Al: 0.5%,
Mn: 0.4%, P: 0.015%, S: 0.0015%, Ti: 0.0020%, N:
0.0018%, and Cu: 0.002%, and a balance being composed
of Fe and inevitable impurities were prepared. The
steel ingots had a length of 500 mm, a width of 400
mm, and a thickness of 250 mm.
[0031] The steel ingots were then heated at 1170°C
(hot rolling heating temperature ST), in a furnace for
1 hour. Thereafter, the steel ingots were taken out
of the furnace and, after various waiting periods,
subjected to five passes in total of rough rolling,
whereby rough-rolled steel sheets with a thickness of
40 mm were obtained. The temperatures of the steel
sheets measured at a fifth pass (rough rolling finish
temperature RT) were of nine kinds presented in Table
1 depending on the waiting period. Subsequently, the
rough-rolled steel sheets were subjected to six
passes of finish rolling, whereby hot-rolled steel
sheets with a thickness of 2.2 mm were obtained.
[0032] Then, both edges in the width direction of
each of the hot-rolled steel sheets were observed
11 _
under an optical microscope and edge cracks within a
range of a length of 20 mm from the edges were
counted. The results are presented in Table 1.
[0033]
[Table 1]
TABLE 1
[0034] As presented in Table 1, in each of numerals
No. 2 to No. 8 (examples), in which the rough rolling
finish temperature RT was not lower than 800°C nor
higher than 1100°C, the rolling load was appropriate
and the-number of edge cracks was 3 or less
indicating a good result. In each of numerals No. 4
to No. 7 among them, in which the rough-rolling
finish temperature RT was not lower than 900°C nor
higher than 1080°C, the rolling load was not as high
as those of numerals No. 2 and No. 3, and the number
of edge cracks is 1 or less indicating a better
result. Further, in each of numerals No. 5 and No.
- 12
6, in which the rough rolling finish temperature RT
was not lower than 950°C nor higher than 1060°C, the
rolling load was especially low, and the number of
edge cracks was 0 indicating an especially good
result.
[0035] On the other hand, in a numeral No. 1
(comparative example), the rough rolling finish
temperature RT was lower than 800°C, so that the load
of finish rolling was too high, failing to obtain a
hot-rolled steel sheet with a thickness of 2.2 mm.
In a numeral No. 9 (comparative example), in which
the rough rolling finish temperature'RT was over
1100°C, 11 edge cracks occurred.
[0036] After the finish rolling, the hot-rolled
steel sheet annealing was performed on the hot-rolled
steel sheets at 1000°C for 80 seconds, and thereafter
cold-rolling was performed until the thickness became
0.50 mm. Subsequently, finish annealing was
performed at 1000°C for 30 seconds. Then, application
and baking of a coating were performed to form an
insulating coating agent film.
[0037] Thereafter, the core loss was measured by the
Epstein method. The core loss W15/50 in each of
numerals No. 2 to No. 9 was 2.,4 W/kg level indicating
a good result.. The core loss W15/50 is a value of the
core loss when the magnetic flux density is 1.5 T and
the frequency is 50 Hz.
[0038]
(EXAMPLE 2)
- 13 -
Steel ingots (silicon steel materials) each
containing, by mass%, C: 0.0016%, Si: 2.8%, Al: 0.7%,
Mn: 0.4%, P: 0.013%, S: 0.0009%, Ti: 0.0015%, N:
0.001.7%, and Cu: 0.008%, and a balance being composed
of Fe and inevitable impurities were prepared. The
steel ingots.had a length of 500 mm, a width of 400
mm, and a thickness of 250 mm.
[0039] The steel ingots were then heated in a
furnace for 1 hour. The temperatures of heating (hot
rolling heating temperature ST) were set to seven
kinds presented in Table 2. Thereafter, the steel
ingots were taken out of the furnace and subjected to
five passes in total of rough rolling, whereby roughrolled
steel sheets with a thickness of 40 mm were
obtained. The temperatures of the steel sheets
measured at a fifth pass (rough rolling finish,
temperature RT) were of seven kinds presented in
Table 2 depending on the hot rolling heating
temperature ST. Subsequently, the rough-rolled steel
sheets were subjected to six passes of finish
rolling, whereby hot-rolled steel sheets with a
thicknes-s of 2.0 mm were obtained.
[0040] Then, both edges in the width direction of
each of the hot-rolled steel sheets were observed
under an optical microscope and edge cracks within a
range of a length of 20 mm from the edges were
counted. The results are presented in Table 2.
[0041]
[Table 2]
- 14 -
TABLE 2
NUMERAL
No.
11
12
13
14
15
16
17
HOT ROLLING ROUGH ROLLING
HEATING FINISH
TEMPERATURE TEMPERATURE
ST (°C) RT (°C)
930 1 790
1010 1 880
1050
1100
1170
1190
920
980
1050
1070
1240 1105
NUMBER OF
EDGE CRACK
(WITHIN 20mm)
REMARKS
COMPARATIVE
EXAMPLE
NOTHING EXAMPLE
(HIGH ROLLING LOAD)
EXAMPLE
NOTHING (SLIGHTLY HIGH
NOTHING
NOTHING
1
13
ROLLING LOAD)
EXAMPLE
EXAMPLE
EXAMPLE
COMPARATIVE
EXAMPLE
[0042] As presented in Table 2,,in each of numerals
No. '12 to No. 16 (examples),
heating temperature ST
in which the hot rolling
was not lower than 1000°C nor
higher than 1200°C and the rough rolling finish
temperature RT was not lower than 800°C nor higher
than 1100°C, the rolling load was appropriate and the
number of edge cracks was 3 or less indicating a good
result. In each of numerals No. 13 to No. 16 among
them, in which the hot rolling heating temperature ST
was not lower than 1040°C nor higher than 1200°C and
the rough rolling finish temperature RT was not lower
than 900°C nor higher than 1080°C,.the rolling load
was not as high as that of numeral No. 12 and the
number of edge cracks is 1 or less indicating a
better result. Further, in each of numerals No. 14
and No. 15, in which the hot rolling heating
temperature ST was not lower than 1060°C nor higher
than 1180°C and the rough rolling finish temperature
RT was not lower than 950°C nor higher than 1060°C,
- 15 -
the rolling load was especially low and the number of
edge cracks was 0 indicating an especially good
result.
[0043] On the other hand, in a numeral No. 11
(comparative example), the hot rolling heating
temperature ST was lower than 1000°C and the rough
rolling finish temperature RT was lower than 800°C, so
that the load of finish rolling was too high, failing
to obtain a hot-rolled, steel sheet with a thickness
of 2.0 mm. In a numeral No. 17 (comparative
example), in which the hot rolling heating
temperature ST was over 1200°C and the rough rolling
finish temperature RT was over 1100°C, 13 edge cracks
occurred.
[0044] After the finish rolling, the hot-rolled
steel sheet annealing was performed on the hot-rolled
steel sheets at 1050°C for 60 seconds, and thereafter
cold-rolling was performed until the thickness became
0.35 mm. Subsequently, finish annealing was
performed at 1020°C for 20 seconds. Then, application
and baking of a coating agent were performed to form
an insul--ating coating film.
[0045] Thereafter, the core loss was measured by the
Epstein method. The core loss W15/50 in each of
numerals No. 12 to No. 17 was 2..2 W/kg level
indicating a good result.
[0046]
(EXAMPLE 3)
Steel ingots (silicon steel materials) each
- 16
containing, by mass%, C: 0.0018%, Si: 3.1%, Al: 1.0%,
Mn: 0.2%, P: 0.0230, S: 0.00110, Ti: 0.0010%, Cu:
0.03%, and N in six kinds of amount presented in
Table 3, and a balance being composed of Fe and
inevitable impurities were prepared. The steel
ingots had a length of 500 mm,. a width of 130 mm, and
a thickness of 100 mm.
[0047] The steel ingots were then heated at 1170°C
(hot rolling heating temperature ST) for 1 hour.
Thereafter, the steel ingots were taken out of the
furnace and subjected to five passes in total of
rough rolling, whereby rough-rolled steel sheets with
a thickness of 30 mm were obtained. The temperatures
of the steel sheets measured at a fifth pass (rough
rolling finish temperature RT) were 1050°C.
Subsequently, the rough-rolled steel sheets were
subjected to six passes of finish rolling, whereby
hot-rolled steel sheets with a thickness of 2.0 mm
were obtained.
[0048 ] Then, both edges in the width direction of
each of the hot-rolled steel sheets were observed
under an optical microscope and edge cracks within a
range of a length of 20 mm from the edges were
counted. The results are presented in Table 3.
[0049] After the finish rolling, the hot-rolled
steel sheet annealing was performed on the hot-rolled
steel sheets at 1030°C for 90 seconds, and thereafter
cold-rolling was performed until the thickness became
0.50 mm. Subsequently, finish annealing was
- 17 -
performed at 1010°C for 30 seconds . Then, application
and baking of a coating agent
an insulating coating film.
[0050] Then, the core losses
single sheet tester (SST).
in Table 3. Note that the
were performed to form
were measured using a
The results are presented
value of the core loss
W15/50 presented in Table 3 is an average value of the
core losses W15/50 in the rolling direction (Ldirection)
and the width
[0051]
[Table 3]
TABLE 3
NUMERAL N CONTENT NUMBER OF
No. (MASS%) E®GE CRACK
(WITHIN 20mm)
21 0.0008 4
22
23
24
25
26
0.0015
0.0021
0.0026
0.0032
0.0044
NOTHING
NOTHING
NOTHING
NOTHING
NOTHING
direction (C-direction)
IRON LOSS I
REMARKS
W15/50 (W/kg)
2.35
2.36
2.38
2.42
2.53
2.68
COMPARATIVE
EXAMPLE
EXAMPLE
EXAMPLE
EXAMPLE
COMPARATIVE
EXAMPLE
COMPARATIVE
EXAMPLE
[0052] As presented in Table 3 , in each of numerals
No. 22 to No . 24 (examples), in which the N content
in the silicon steel sheet was not . less than 0.0010%
nor more than 0.0030% , the number of edge cracks was
0 and the core loss W15/50 was not higher than 2.50
W/kg indicating a good result . In each of numeralc
No. 22 and No. 23 among them , in which the N content
was not less than 0.0010 % nor more than 0.0025%, the
core loss W15 / 50 was not higher than 2. 40 W/kg
indicating a better result.
18 -
INDUSTRIAL APPLICABILITY
[0053] The present invention is usable, for example,
in an electrical steel sheet manufacturing industry
and in an electrical steel sheet using industry.

CLAIMS
1. A method of manufacturing a non-oriented
electrical steel sheet, comprising:
heating a silicon steel material at a temperature
not lower than 1000°C nor higher than 1200°C;
hot rolling the heated silicon steel material to
obtain a steel strip;
cold rolling the steel strip; and
then finish annealing the steel strip,
wherein the silicon steel material contains, by
mass%,
C: not less than 0.0001% nor more than 0.005%;
Si: not less than 1.0% nor more than 4.0%;
Al: not less than 0. 2% nor more than 3.0%;
Mn: not less than 0.2% nor more than 1.5%;
P: not less than 0.001 nor more than 0.1%;
S: not less than 0.0001% nor more than 0.0050%;
Ti: not less than 0.0001% nor more than 0.0030%;
and
N: not less than 0.0010% nor more than 0.0030%;
and
a balance being composed of Fe, and inevitable
impurities,
wherein where a Si content (mass% ), an Al content
(mass %), and a Mn content ( mass% ) are expressed by
[Si], [Al], [Mn] respectively, a relation of
"[Si]+2x[Al]-[Mn]?2.0" is established, and
wherein a finish temperature of rough rolling of
the hot rolling is set to not lower than 800°C nor
- 20 -
higher than 1100°C.
2. The method of manufacturing a non-oriented
electrical steel sheet according to claim 1, wherein
the finish temperature of the rough rolling of the
hot rolling is set to not lower than 900°C nor higher
than 1080°C.
3. The method of manufacturing a non-oriented
electrical steel sheet according to claim 1, wherein
the finish temperature of the,rou.gh rolling of the
hot rolling is set to not lower than 950°C nor higher
than 1060'C.
4. The method of manufacturing a non-oriented
electrical steel sheet according to any one of claim
i toclaim'3, wherein the heating of the silicon
steel material before the hot rolling is performed-in
a range of not lower than 1040°C nor higher than
1200°C.
5. The method of manufacturing a non-oriented
electrical steel sheet according to any one of.claim
1 to claim 3, wherein the heating of the silicon
steel material before the hot rolling is performed in
a range of not lower than 1060°C nor higher than
1180°C.
-6.--The method of manufacturing a non-oriented
electrical steel sheet according to any one of claim
1 to claim 5, wherein a N content in the silicon
steel material is not less than 0.0010% nor higher
than 0.00250.