FIELD OF THE INVENTION
The present invention relate to a low carbon , cold rolled, annealed and skin passed Extra
Deep Drawing (EDD) Quality Steel such as those used in automobile outer body
components and the like, and produced following the BOF-CC-HSM-CR-Batch annealing
and Skin Passing route. In particular, the invention is specifically directed to such steel
sheets having high formability along with good surface finish and flatness. More
particularly, the invention relate to a steel product developed for utilization in making such
components, where high elongation and moderate drawability are essentially required.
Such (EDD) Quality Steel of the invention are also desired to have non-aging and greater
shelf life property, over the existing steel products of the similar category. Importantly,
such steel is directed to further have the potential for energy saving by way of possible
lowering loads by a magnitude of about 50% involved during skin passing of the cold
rolled and annealed coils, by favored reduction of SAI prior to skin pass to thereby favour
effective and advantageous industrial production of such grade of quality steel.
BACKGROUND ART
Conventionally, the variety of Low carbon cold rolled, annealed and skin passed extra deep
drawing (EDD) quality steel sheets are mainly used to form outer body components of
automobiles, needing considerable deformation during forming. These steels have a
composition comprising low carbon, normally not exceeding 0.04% by wt., low manganese
<0.15% by wt., low silicon <0.03% by wt., low sulphur 0.01% (max) by wt. and low
phosphorus 0.015% (max) by wt. The variants of this quality of steel, however, find their
application and use and accordingly the corresponding product categories/specification
differentiated mainly on the basis of elongation levels and surface quality.
There has therefore been a continuing need in the art to develop EDD quality steel that
would further provide highest elongation combined with substantially higher drawability of
conventional low carbon cold rolled and skin passed sheet coils. Further, the process of
such manufacture should also ensure cost-effective manufacture of the EDD steel,
enabling its wide economic application in industries, particularly for components
manufacturing in automobile industries.
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OBJECTS OF THE INVENTION:
It is thus the basic object of the present invention to provide for a cold rolled, annealed
and skin passed steel sheets in the form of coils which would achieve highest elongation
levels combined with reasonably high drawability within its class.
A further object of the present invention directed to a variety of low carbon cold rolled,
annealed and skin passed EDD quality steel, which could be manufactured by Basic
Oxygen Furnace (BOF)-Continuous Casting (CC)-Hot Strip Rolling (HSM)-Cold Rolling (CR)-
Batch Annealing-Skin Passing route, and achieve the desired properties of improved
elongation and reasonably high draw ability in the resulting product.
A still further object of the present invention is directed to the provision of selective EDD
quality steel composition adapted to achieve desired properties in the resulting steel, for
possible favored reduction in skin pass load.
A still further object of the present invention directed to said EDD quality steel wherein
these steels have the additional advantage of energy saving because of the lower loads
involved during skin passing of the cold rolled and annealed coils, ranging up to about
50%.
A still further object of the present invention directed to said EDD quality steel wherein, by
way of preferred processing route and selective alloy composition, such steels could exhibit
more non aging than the conventional steels in similar category and hence providing
enhanced shelf lives.
A still further object of the present invention to provide EDD quality steel is directed to
favour its advantageous and cost-effective end use by the secondary producers in the
form of HR coils, whereby the advantage of lower load during skin pass can be offered as a
product attribute to the cold reducers, procuring such HR coils.
Yet another object of the present invention involving the EDD quality steel is directed to
use by the secondary producers in the form of HR coils, whereby the advantageous energy
saving benefit could be achieved by the cold reducer, while an increase in ductility/higher
3

elongation is obtained in the skin passed coils as the final product, after cold reduction and
annealing.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided a low
carbon extra deep drawing (EDD) quality steel having superior ductility with reasonably
high drawability comprising:
low carbon of upto 0.04% by wt.;
low manganese less than 0.15% by wt.;
low silicon less than 0.03% by wt.;
low sulphur upto 0.01% max;
low phosphorous upto 0.015% max; and
titanium in amounts of 0.008-0.012% by wt.
A further aspect of the present invention directed to a low carbon extra deep drawing
(EDD) quality steel composition wherein the steel composition(on wt % basis) comprises ,
Carbon about 0.04%;
Manganese about 0.15%;
Silicon about 0.03%;
Sulphur about 0.01%;
Phosphourous 0.015% ;
4

Aluminium about 0.04%;
Titanium about 0.01%.
A still further aspect of the present invention directed to said low carbon extra deep
drawing (EDD) quality steel composition having elongation /ductility of skin passed coils in
the range of 39% to 46% with a load of only about 300T.
According to another aspect of the present invention directed to a low carbon extra deep
drawing (EDD) quality steel composition having reduced strain aging index in the range of
2.0% to 2.2%, in cold rolled and annealed coils,i.e. before skin pass rolling.
A still further aspect of the present invention directed to said low carbon extra deep
drawing (EDD) quality steel composition having average plastic anisotrophy ratio in the
range of 1.5 to 1.7, preferably 1.6 to 1.7;
plane strain forming limit (FLD0) in the range of 51% to 53% preferably about 52%;
A still further aspect of the present invention directed to a process for the manufacture of
a low carbon extra deep drawing (EDD) quality steel , comprising:
providing a steel composition comprising low carbon of upto 0.04% by wt.;low manganese
less than 0.15% by wt.; low silicon less than 0.03% by wt.; low sulphur upto 0.01% max;
low phosphorous upto 0.015% max; and titanium in amounts of 0.008-0.012% by wt.;
making the steel with said composition in BOF followed by continuous casting and hot
rolling into coils of thickness in the range of 3.0-5.0 mm with or without further subjecting
5

to cold rolling to thereby obtain EDD steel having superior ductility with reasonably high
draw ability.
A still further preferred aspect of the present invention directed to a process for the
manufacture of a low carbon extra deep drawing (EDD) quality steel , wherein the
selective addition of Titanium in the steel composition provides for decreasing the strain
aging index to about 2% in the cold rolling and annealed coils.
A still further aspect of the present invention directed to a process for the manufacture of
a low carbon extra deep drawing (EDD) quality steel, comprising carrying out skin passing
after annealing with reduced load in the range of .. to .. preferably only about 300T for
skin passing of 1250-1400 mm wide cold rolled and annealed coils to thereby increase
ductility of the skin passed coils.
According to yet another advantageous aspect of the present invention directed to a
process for the manufacture of a low carbon extra deep drawing (EDD) quality steel,
comprising achieving energy saving by required reduced load for skin passing by about
50% without compromising on the formability, surface appearance and flatness of theses
coils.
The present invention and its objects and advantages are described in greater details with
reference to the accompanying non limiting exemplary illustrations and examples.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is the illustration of the Forming Limit Diagram(FLD0) of conventional EDD cold
rolled sheet, without Ti addition.
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Figure 2: is the illustration of the Forming Limit Diagram of the EDD CR sheet with addition
of Ti, according to the present invention.
Figure 3: is the bar chart illustrating the requirement of rolling load of 600T(approx.) for
conventional EDD sheet CR coils, wherein, the SAI is 8% before skin passing.
Figure 4: is the bar chart illustrating the reduction in rolling load requirement by about
50%, requiring only about 300T load during skin passing for EDD with Ti addition as of the
present invention, favoring a SAI of 2.1% before skin passing.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING FIGURES
The present invention is directed to development of a steel variety/product which offers
superior elongation combined with moderate drawability properties while ensuring energy
saving while skin passing of cold rolled annealed sheets/coils, along with surface finish,
flatness and enhanced non aging properties. An optimum addition of titanium not
exceeding 0.012 wt %, and preferably 0.01% in the final product in a steel composition
comprising 0.04C-0.15Mn-0.03Si-0.01S-0.015P-0.04AI-70 ppm N, has resulted in superior
ductility measured by % elongation without a drastic reduction in drawability measured as
average plastic anisotropy ratio, ravg.. The manufacturing process of the steel involves first
making of the steel in BOF followed by continuous casting, then hot rolling into coils of
thickness 3.0-5.0 mm, pickling, reduction by cold rolling by ~ 70 %, annealing in batch
annealing furnace and finally skin passing.
The present invention is directed to developing a grade of cold rolled annealed and skin
passed steel involving the usual process of manufacturing to obtain desired cold rolled
extra deep drawing (EDD) quality coils following detailed methodology of the individual
process steps as follows:
To obtain desired ~0.01% Ti in the final product, 100-120 kg of ferro-titanium, containing
a minimum of 35% titanium, is added in a ~300 T heat during secondary refining after the
primary steel has been made in the BOF. The addition of selective quantity of titanium has
led to a decrease the Strain Aging Index (SAI) to 2% in the cold rolled and annealed coils
according to the present invention as compared to the SAI of 8% in conventional cold
rolled and annealed coils of EDD grade steel where no titanium is added. The introduction
7

of titanium in the range of 0.008-0.012 % but not above 0.012% and reduction in the skin
passing load to ~300 T in no way deteriorates other features of the product, namely,
formability, flatness and surface appearance of the cold rolled and skin passed coils.
Due to the decrease in SAI achieved through selective Ti addition, made possible skin
passing for EDD quality cold rolled and annealed steel coils at lower loads due to a
decrease in SAI. While the skin passing of 1250mm-1400 mm wide conventional Ti-free
cold rolled and annealed coils usually carried out under a load of ~600 T, the load
requirement for skin passing according to the EDD with selective Ti addition up to 0.012%
has been observed to be only ~300T, meaning a load reduction of 50%. This results in
increased ductility of the skin passed coils by ~2% compared to conventional skin passed
EDD coil with ~ 600 T load.
Reference is now invited to accompanying Figure 1 which is the illustration of the Forming
Limit Diagram (FLD) of the cold rolled, annealed and skin passed conventional EDD coil of
1.18 mm thickness wherein the plane strain forming limit FLD0 appearing at 49%. The
accompanying Figure 2 illustrates that for titanium added EDD coil of the same thickness,
the plane strain-forming limit (FLD0) appearing at a slight higher range of 52%.
Reference is next invited to accompanying Figure 3 and Figure 4, that illustrates the
claimed advantageous lower load (~300T) for skin passing of ~1250 mm wide cold rolled
and annealed coils of EDD grade steel, resulting in higher elongation in the skin passed
coils. The SAI is found to be in the order of 8% before skin passing. It is observed that
there is a gain of ~2% in elongation e.g. 39% for CR EDD sheet without Ti addition and
rolling load of 600T to 41.4% for EDD with selective Ti addition and reduced rolling load by
50% to 300T, without deterioration in other properties like flatness, surface appearance
and formability, in the ultimate product.
The load during skin passing can be reduced because of the reduced SAI value of ~2% in
the titanium added cold rolled and annealed coils, before skin pass. Conventionally, a load
of ~600 T is used for skin passing, which is much higher than what is required for the
suppression of stretcher strains and control of flatness as represented in accompanying
Figure 4, comparing the effect of skin pass on % elongation at 600t versus the same at
300T. This is because the SAI in conventional coils is in much higher range of ~8%, before
the skin pass.
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According to an optional aspects of the present invention of selectively Ti alloyed EDD steel
sheets obtained in the form of hot rolled coils for consumption/processing by the
secondary producers, wherein the advantage of the need for a lower load during skin
passing and thereby resultant saving in energy consumption, can be passed on to the cold
reducers who procure these hot rolled coils. Therefore, an increase in ductility in terms of
higher elongation (nearly 2 to 3%)in the skin passed coils after cold reduction and
annealing, can be achieved in the final product. These properties enable cold reducers to
avail the advantage of energy saving because of rolling load reduction by ~50% skin
passing without compromising on the formability, surface appearance and flatness of these
coils. Thus the present process is directed to either HR EDD coils for consumption by
secondary cold reducers units or CR annealed and skin passed coils for use by automobile
and other components manufacturing industries , where extremely high order of
elongation with moderate formability/drawability is the basic requirement.
The following process charts along with parameter values for each step involved in either
production of hot rolled (HR) as well as cold rolled (CR) EDD steel coils with the selective
addition of titanium, according to the present invention are the illustrations of the
Examples 1 & 2 as obtained in alternate embodiments of the EDD steel according to the
present invention.
EXAMPLE 1:
PROCESS CHART FOR MAKING SUPER EDD STEEL (<0.03 C) HR COIL:
1. Aimed Chemistry:
-1 Heat with Ti addition:

%c %Mn %S %P %Si %AI %Ti
0.03 max 0.15 max 0.01 max 0.015 max 0.02 max 0.03 min 0.01 max
-1 Heat without Ti addition: same as above
9

a.
02 Purity(99.9%)
minimum Oxygen plant to be informed at least 8 Hrs in advance
b. CBT Procedure Procedure #7 to be followed, combined blowing up to
0.02%C/3' post purging
c. Aimed Bath Chemistry (wt
%) %C=0.02 max;
%P=0.010max;
%S=0.020max;(No Reblow)
d. Tapping time 7 minutes minimum
e. Tapping Temperature 1660-1670°C
f. Slag Arrester Ram Tree, Dart(BOTH), Carry Over Slag<5 kg/T
g. Laddie additions during
tapping 50 kg Coke at Ladle Bottom before TAP;
Med. C Fe-Mn:100kg:Mn Metal:300kg
Al bar:400-450kg(AI addition started after half ladle filing)
Lime:1.5T
h. Ladle Condition Red hot circulation ladle(1100/1200°C)
Should not be the first heat on lining

a Arcing 2'-3'
b Homogenization Purging Ar rate: 300/350 NL/min./plug
c Samples To be collected for both liquid steel and slag for analysis
d Measurements Oxygen Potential and temperature to be recorded
e Additions Lime: 500kg, Bauxite:250-300kg
f Slag making and
treatment As per normal practice of temperature correction and
arcing
g Addition of Mn metal 100kg (if necessary)
h Addition of Ca-Fe As per normal practice
i Cleansing Purging 3'-5' after Ca-Fe addition
j SRU leaving temperature 1600°C for 1st heat, 1590°C for 2nd heat and beyond
k Treatment Time 30min
4. CASTER PRACTICE

a Super heat 25°C
b Casting Powder As per normal practice i.e. low Carbon group granules
c Secondary cooling Hard
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d Casting Speed As per norm
e Macro Structure study 2 samples to be taken, one from each stand
f Slab dimension ---

b. HOT ROLLING
a Descalers All regular descalers should be working
b Thickness/tolerance 3.2mm
c Width/tolerance 1270mm
d Soaking temperature 1250-1280°C
e Finishing temperature 890+ 10°C for<2.5mm
910± 10°C for>2.5mm
Delay on run out table
f Coiling temperature 550± 10°C
EXAMPLE 2:
PROCESS CHART FOR MAKING SUPER EDD (<0.03 C) CR COIL:
1. AIMED CHEMISTRY
-1 Heat (<0.03c, Without Ti)

%c %Mn %S %P %Si %AI %Ti
0.03max 0.15max 0.0lmax 0.015max 0.02max 0.03 min -
-2 Heats(0.04C, 1 with Ti and 1 without Ti)

%c %Mn %S %P %Si %AI %Ti
0.04max 0.15max 0.0lmax 0.015max 0.02max 0.03 min 0.01
0.04max 0.15max 0.0lmax 0.015max 0.02max 0.03 min -

2. BOF PRACTICE
a. O2 Purity(99.9%)
minimum Oxygen plant to be informed at least 8 Hrs in advance
b. CBT Procedure Procedure #7 to be followed, combined blowing up to
0.02%C/3' post purging
11

c.
Aimed Bath Chemistry (wt
%) %C=0.02 max;
%P=0.010max;
%S=0.020max;(No Reblow)
d. Tapping time 7 minutes minimum
e. Tapping Temperature 1660-1670°C
f. Slag Arrester Ram Tree, Dart(BOTH), Carry Over Slag<5 kg/T
g. Laddie additions during
tapping 50 kg Coke at Ladle Bottom before TAP;
Med. C Fe-Mn:100kg:Mn Metal:300kg
Al bar:400-450kg(AI addition started after half ladle filing)
Lime:1.5T
h. Ladle Condition Red hot circulation ladle(1100/1200°C)
Should not be the first heat on lining

a Arcing 2'-3'
b Homogenization Purging Ar rate:300/350 NL/min./plug
c Samples To be collected for both liquid steel and slag for analysis
d Measurements Oxygen Potential and temperature to be recorded
e Additions Lime:500kg, Bauxite:250-300kg
f Slag making and
treatment As per normal practice of temperature correction and
arcing
g Addition of Mn metal 100kg (if necessary)
h Addition of Ca-Fe As per normal practice
i Cleansing Purging 3'-5' after Ca-Fe addition
j SRU leaving temperature 1600°C for 1st heat, 1590°C for 2nd heat and beyond
k Treatment Time 30min

a Super heat 25°C
b Casting Powder As per normal practice i.e. low Carbon group granules
c Secondary cooling Hard
d Casting Speed As per norm
e Macro Structure study 2 samples to be taken, one from each stand
f Slab dimension ---
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b. HOT ROLLING
a Descalers All regular descalers should be working
b Thickness/tolerance As per orders
c Width/tolerance 1420mm
d Soaking temperature 1250-1280°C
e Finishing temperature 890+ 10°C for<2.5mm
910± 10°C for>2.5mm
Delay on run out table
f Coiling temperature 620± 10°C
5. PICKLING
- The hot rolled coils will be preferably pickled in HCL; During pickling, proper acid
concentration and bath temperature shall be maintained as per technological
norms. Precautions are to be taken to prevent any acid /salt carry over with the
strip after pickling.
- Full width samples shall be collected from a few selected coils after 12m from head
end for measurement of profile, evaluation of mechanical properties and grain size
in Laboratory.
6.COLD ROLLING
Coils are rolled preferably in tandem mill -I within 16 hrs. after pickling and 1000T
of rolling after rolling change of last stand.
The roll roughness of last stand of TM-I is to be kept 2.8μm min. The oil content in
emulsion is maintained in the range of 1.0 to 2.5% in stand 1 to 4. Further, Fe
content should be controlled less than 200mg/l.
- The coiler tension is maintained below 3.5kg/mm2. Care is taken to ensure no
emulsion carry over.
- The hot rolled coils are processed into following sizes:
1.2xl420mm:124 Tons(<0.03C)
2.0xl420mm:124 Tons(<0.03C)
1.33xl420mm:186 Tons(<0.04C)
1.50xl420mm:248 Tons(<0.04C)
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A comparative analysis of the properties that have been obtained in the HR as well as CR
coils both in the conventional product of EDD and in the present selectively Titanium
added EDD HR and CR coils, is presented in the following Table 1.
Table 1: Comparative Analysis of the Properties Extra Deep Drawing (EDD) Hot
Rolled and Cold Rolled Steel coils, with and without Ti addition.

Parameter Conventional EDD Ti-Bearing EDD
Chemistry C Mn Si Ti C Mn Si Ti
( wt %) 0.04 0.13 0.03 - 0.04 0.16 0.03 0.009
Hot Rolled Coils
YS (MPa) 260-290 196-250
% Elong. 38-42 40-46
Cold Rolled Coils
YS (MPa) 180-210 170-220
% Elong. 38-42 39-46
r avg. 1.8 1.6-1.7
SAI ( %) ~8 ~2
FLD0 (%) ~49 ~52
The present invention directed to super EDD quality steel further ensure reduced SAI
accompanied with a corresponding reduced load during skin passing, enhanced ductility
and drawability properties in said Ti added EDD steel coils without compromising the other
prevalent characteristic features of the existing product like formability and surface
quality. The average plastic anisotropy ratio ravg. is decreased only marginally in the range
of 1.6-1.7 in titanium added CR coils compared to 1.8 in conventional EDD CR coils as
already presented in preceding Table 1. The plane strain forming limit (FLD0), another
measure of formability, has in fact shown a slight increase from ~49% in conventional
EDD CR coils, to ~52% in titanium added CR EDD coils as presented in preceding Table 1.
It is thus possible by way of this invention, directed to developing a Low carbon cold
rolled, annealed and skin passed Extra Deep Drawing (EDD) quality steel sheet, having
selective Ti addition in the range from 0.008 to up to 0.012 wt %, such as to favor
lowering of rolling load by about 50% during skin pass of Cold Rolled and annealed EDD
sheet coils, due to favored reduction of Strain Aging Index (SAI) from 8% to about 2%
14

before skin passing, due to said selective Ti addition and thus providing desired
mechanical properties in resulting steel sheets such as much superior elongation
exceeding 41% combined with moderate drawability(ravg of 1.6-1.7), non aging and
enhanced shelf life, apart from the conventional attributes of surface finish and flatness.
Thus the super EDD steel products of the invention having either HR coils for the
consumers like cold reducers or the EDD CR and annealed coils for preparing deep drawn
components such as the outer body components of automobiles and the like, ensuring
possibility of wide industrial applications, in energy efficient manner due to reduction in
rolling load requirement for the cold reduction during skin pass.
15

WE CLAIM:
1. A low carbon extra deep drawing (EDD) quality steel having superior ductility with
reasonably high draw ability comprising:
low carbon of upto 0.04% by wt.;
low manganese less than 0.15% by wt.;
low silicon less than 0.03% by wt.;
low sulphur upto 0.01% max;
low phosphorous upto 0.015% max; and
titanium in amounts of 0.008-0.012% by wt.
2. A low carbon extra deep drawing (EDD) quality steel composition as claimed in claim 1
wherein the steel composition comprises
Carbon about 0.04%;
Manganese about 0.15%;
Silicon about 0.03%;
Sulphur about 0.01%;
Phosphourous 0.015% ;
Aluminium about 0.04%;
Titanium about 0.01%.
16

3. A low carbon extra deep drawing (EDD) quality steel composition as claimed in anyone
of claims 1 or 2 having elongation /ductility of skin passed coils in the range of 39% to
46% with a load of only about 300T.
4. A low carbon extra deep drawing (EDD) quality steel composition as claimed in anyone
of claims 1 to 3 having reduced strain aging index in the range of 2.0% to 2.2%, in cold
rolled and annealed coils,i.e. before skin pass rolling.
5. A low carbon extra deep drawing (EDD) quality steel composition as claimed in anyone
of claims 1 to 4 having average plastic anisotrophy ratio in the range of 1.5 to 1.7,
preferably 1.6 to 1.7;
plane strain forming limit (FLD0) in the range of 51% to 53% preferably about 52%;
6. A process for the manufacture of a low carbon extra deep drawing (EDD) quality steel
as claimed in anyone of claims 1 to 5 comprising:
providing a steel composition comprising low carbon of upto 0.04% by wt.;low manganese
less than 0.15% by wt.; low silicon less than 0.03% by wt; low sulphur upto 0.01% max;
low phosphorous upto 0.015% max; and titanium in amounts of 0.008-0.012% by wt.;
making the steel with said composition in BOF followed by continuous casting and hot
rolling into coils of thickness in the range of 3.0-5.0 mm with or without further subjecting
to cold rolling to thereby obtain EDD steel having superior ductility with reasonably high
draw ability.
17

7. A process for the manufacture of a low carbon extra deep drawing (EDD) quality steel
as claimed in claim 6 wherein the selective addition of Titanium in the steel composition
provides for decreasing the strain gauge index to about 2% in the cold rolling and
annealed coils.
8. A process for the manufacture of a low carbon extra deep drawing (EDD) quality steel
as claimed in anyone of claims 6 to 7 comprising carrying out skin passing after annealing
with reduced load in the range of 280T to 320T, preferably only about 300T for skin
passing of 1250mm-1400 mm wide cold rolled and annealed coils to thereby increase
ductility of the skin passed coils.
18
9. A process for the manufacture of a low carbon extra deep drawing (EDD) quality steel
as claimed in anyone of claims 6 to 8 comprising achieving energy saving by required
reduced load for skin passing by about 50% without compromising on the formability,
surface appearance and flatness of theses coils.
10. A low carbon extra deep drawing (EDD) quality steel having superior ductility with
reasonably high draw ability and its process for manufacture substantially as
hereindescribed and illustrated with reference to the accompanying examples and figures.

A low carbon, cold-rolled, annealed and skin passed Extra Deep-Drawing(EDD) Quality
Steel for use in automobile outer body components and the like, produced following the
BOF-CC-HSM-CR-Batch annealing and Skin Passing route. In particular, the invention is
directed to steel sheets having high formability along with good surface finish and flatness.
More particularly, the invention relate to a steel product developed for utilization in making
such components, where high elongation and moderate drawability are essentially required. Such (EDD) Quality Steel are also haveing non-aging and greater shelf life property, over the existing steel products of the similar category. Importantly, such steel further having the potential for energy saving by way of possible lowering rolling loads by a magnitude of about 50% involved during skin passing of the cold-rolled and annealed coils, by favored reduction of SAI prior to skin pass to thereby favour effective and advantageous industrial production of such grade of quality steel.