Note: Descriptions are shown in the official language in which they were submitted.
CA 02882361 2017-01-25
Ferritie Stainless Steel with Excellent Oxidation Resistance, Good High
Temperature
Strength, and Good Formability
Eizo Yoshitake
[00011 The present application claims priority from provisional patent
application serial
no. 61/695,771, entitled "Ferritic Stainless Steels with Excellent Oxidation
Resistance with Good High Temperature Strength and Good Formability," filed
on August 31, 2012, and non-provisional patent application serial no.
13/837,500,
entitled "Ferri& Stainless Steel with Excellent Oxidation Resistance, Good
High
Temperature Strength, and Good Formability," filed on March 15, 2013.
BACKGROUND
[0002] It is desirable to produce a ferritic stainless steel with oxidation
resistance, high
= temperature strength, and good formability characteristics. Columbium and
copper are added in amounts to provide high temperature strength, and silicon
and
manganese are added in amounts to provide oxidation resistance. The present
terrific stainless steel provides better oxidation resistance than known
stainless
steels such as 18Cr-2Mo and 15Cr-Cb-Ti-Si-Mn. In addition, the present
ferritic
stainless steel is less expensive to manufacture than other stainless steels
such as
18Cr-2Mo and can he produced without a hot band annealing step.
SUMMARY
[0003] The present ferritic stainless steel are produced with titanium
additions and low
aluminum concentration to provide room temperature formability from equiaxed
as-cast grain structures, as disclosed in U.S. Patent Nos. 6,855,213 and
5,868,875.
Columbium and copper are added to the terrific stainless steel for high
temperature strength and silicon and manganese are added to improve oxidation
resistance.
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DETAILED DESCRIPTION
[0004] The ferritic stainless steel is produced using process conditions
known in the art
for use in manufacturing terrific stainless steels, such as the processes
described
in U.S. Patent Nos. 6,855,213 and 5,868,875. Columbium and copper are added
to the terrific stainless steel for high temperature strength and silicon and
manganese are added to improve oxidation resistance. It can be produced from
material having an as-cast structure of fine equiaxed grains.
[0005] A ferrous melt for the ferritic stainless steel is provided in a
melting furnace such
as an electric arc furnace. This ferrous melt may be formed in the melting
furnace
from solid iron bearing scrap, carbon steel scrap, stainless steel scrap,
solid iron
containing materials including iron oxides, iron carbide, direct reduced iron,
hot
briquetted iron, or the melt may be produced upstream of the melting furnace
in a
blast furnace or any other iron smelting unit capable of providing a ferrous
melt.
The ferrous melt then will be refined in the melting furnace or transferred to
a
refining vessel such as an argon-oxygen-decarburization vessel or a vacuum-
oxygen-decarburization vessel, followed by a trim station such as a ladle
metallurgy furnace or a wire feed station.
[0006] In some embodiments, the steel is cast from a melt containing
sufficient titanium
and nitrogen but a controlled amount of aluminum for forming small titanium
oxide inclusions to provide the necessary nuclei for forming the as-cast
equiaxed
grain structure so that an annealed sheet produced from this steel also has
enhanced ridging characteristics and formability.
[0007] In some embodiments, titanium is added to the melt for deoxidation
prior to
casting. Deoxidation of the melt with titanium forms small titanium oxide
inclusions that provide the nuclei that result in an as-cast equiaxed fine
grain
structure. To minimize formation of alumina inclusions, i.e., aluminum oxide,
A1203, in some embodiments aluminum may not be added to this refined melt as a
deoxidant and in other embodiments aluminum may be added to this refined melt
in a small fraction. In some embodiments, titanium and nitrogen can be present
in
2
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the melt prior to casting so that the ratio of the product of titanium and
nitrogen
divided by residual aluminum is at least about 0.14.
[00081 If the steel is to be stabilized, sufficient amount of the titanium
beyond that
required for deoxidation can be added for combining with carbon and nitrogen
in
the melt but preferably less than that required for saturation with nitrogen,
i.e., in
. a sub-equilibrium amount, thereby avoiding or at least minimizing
precipitation of
large titanium nitride inclusions before solidification. The maximum amount of
titanium for "sub-equilibrium" is generally illustrated in FIG. 4 of U.S. Pat.
No.
4,964,926. In some
embodiments, one or more stabilizing elements such as columbium, zirconium,
tantalum and vanadium can be added to the melt as well.
[0009] The cast steel is hot processed into a sheet, For this disclosure,
the term "sheet" is
meant to include continuous strip or cut lengths formed from continuous strip
and
the term "hot processed" means the as-cast steel will be reheated, if
necessary,
and then reduced to a predetermined thickness such as by hot rolling. If hot
rolled, a steel slab is reheated to 2000 to 2350 F (1093 -1288 C), hot rolled
using a finishing temperature of 1500¨ 1800 F (816¨ 982 C) and coiled at a
temperature of 1000¨ 1400 F (538 ¨ 760 C). The hot rolled sheet is also known
as the "hot band." In some embodiments, the hot band may be annealed at a peak
metal temperature of 1700 - 2100 F (926 - 1149 C). In other embodiments, the
sheet does not undergo a hot band annealing step. In some embodiments, the hot
band may be descaled and cold reduced at least 40% to a desired final sheet
thickness. In other embodiments, the hot band may be descaled and cold reduced
at least 50% to a desired final sheet thickness. Thereafter, the cold reduced
sheet
can be final annealed at a peak metal temperature of 1800 - 2100 F (982-1149
C).
[00101 The ferritic stainless steel can be produced from a hot processed
sheet made by a
number of methods. The sheet can be produced from slabs formed from ingots or
continuous cast slabs of 50-200 mm thickness which are reheated to 2000 to
2350 F (1093 -1288 C) followed by hot rolling to provide a starting hot
processed sheet of 1 ¨ 7 mm thickness or the sheet can be hot processed from
strip
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continuously cast into thicknesses of 2 ¨ 52 mm. The present process is
applicable to sheet produced by methods wherein continuous cast slabs or slabs
produced from ingots are fed directly to a hot rolling mill with or without
significant reheating, or ingots hot reduced into slabs of sufficient
temperature to
be hot rolled in to sheet with or without further reheating.
[0011] Titanium is used for deoxidation of the ferritic stainless steel
melt prior to casting.
The amount of titanium in the melt can be 0.30% or less. Unless otherwise
expressly stated, all concentrations stated as "%" are percent by weight. In
some
embodiments, titanium can be present in a sub-equilibrium amount. As used
herein, the term "sub-equilibrium" means the amount of titanium is controlled
so
that the solubility product of the titanium compounds formed are below the
saturation level at the steel liquidus temperature thereby avoiding excessive
titanium nitride precipitation in the melt. Excessive nitrogen is not a
problem for
those manufacturers that refine ferritic stainless steel melts in an argon
oxygen
decarburization vessel. Nitrogen substantially below 0.010% can be obtained
when refining the stainless steel in an argon oxygen decarburization vessel
thereby allowing increased amount of titanium to be tolerated and still be at
sub-
equilibrium.
[0012] To provide the nucleation sites necessary for forming as-cast
equiaxed ferrite
grains, sufficient time after adding the titanium to the melt should elapse to
allow
the titanium oxide inclusions to form before casting the melt. If the melt is
cast
immediately after adding titanium, the as-cast structure of the casting can
include
larger columnar grains. The amount of time that should elapse can be
determined
by one of ordinary skill in the art without undue experimentation. Ingots cast
in
the laboratory less than 5 minutes after adding the titanium to the melt had
large
as-cast columnar grains even when the product of titanium and nitrogen divided
by residual aluminum was at least 0.14.
[0013] Sufficient nitrogen should be present in the steel prior to
casting so that the ratio
of the product of titanium and nitrogen divided by aluminum is at least about
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0.14. In some embodiments, the amount of nitrogen present in the melt is <
0.020%.
[0014] Although nitrogen concentrations after melting in an electric arc
furnace may be
as high as 0.05%, the amount of dissolved N can be reduced during argon gas
refining in an argon oxygen decarburization vessel to less than 0.02%.
Precipitation of excessive TiN can be avoided by reducing the sub-equilibrium
amount of Ti to be added to the melt for any given nitrogen content.
Alternatively, the amount of nitrogen in the melt can be reduced in an argon
oxygen decarburization vessel for an anticipated amount of Ti contained in the
melt.
[0015] Total residual aluminum can be controlled or minimized relative to
the amounts
of titanium and nitrogen. Minimum amounts of titanium and nitrogen must be
present in the melt relative to the aluminum. The ratio of the product of
titanium
and nitrogen divided by residual aluminum can be at least about 0.14 in some
embodiments, and at least 0.23 in other embodiments. To minimize the amounts
of titanium and nitrogen required in the melt, the amount of aluminum is
<0.020%
in some embodiments. In other embodiments, the amount of aluminum is
<0.013% and in other embodiments, it is reduced to <0.010%. If aluminum is not
purposefully alloyed with the melt during refining or casting such as for
deoxidation immediately prior to casting, total aluminum can be controlled or
reduced to less than 0.020%. One must be aware that aluminum can be
inadvertently added to the melt as an impurity present in an alloy addition of
another element, e.g., titanium. Titanium alloys may contain as much as 20% Al
which may contribute total Al to the melt. By carefully controlling the
refining
and casting practices, a melt containing <0.020% aluminum can be obtained.
[0016] In addition to using titanium for stabilization, other suitable
stabilizing elements
may also include columbium, zirconium, tantalum, vanadium or mixtures thereof
In some embodiments, if a second stabilizing element is used in combination
with
titanium, e.g., columbium or vanadium, this second stabilizing element may be
limited to < 0.50% when deep formability is required. Some embodiments
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include columbium in concentrations of 0.5% or less. Some embodiments include
columbium in concentrations of 0.28 ¨ 0.43%. Vanadium can be present in
amounts less than 0.5%. Some embodiments of the ferritic stainless steels
include
0.008 ¨ 0.098% vanadium.
[0017] Copper improves high temperature strength. The ferritic stainless
steels contain
1.0 ¨ 2.0% copper. Some embodiments include 1.16-1.31% copper.
[0018] Silicon is generally present in the ferritic stainless steels in
an amount of 1.0 ¨1.7%. In some embodiments, silicon is present in an amount
of 1.27 ¨ 1.35%. A
small amount of silicon generally is present in a ferritic stainless steel to
promote
formation of the ferrite phase. Silicon also enhances high temperature
oxidation
resistance and provides high temperature strength. In most embodiments,
silicon
does not exceed about 1.7% because the steel can become too hard and the
elongation can be adversely affected.
[0019] Manganese is present in the ferritic stainless steel in an amount
of 0.4 - 1.5%. In
some embodiments, manganese is present in an amount of 0.97 ¨ 1.00%.
Manganese improves oxidation resistance and spalling resistance at high
temperatures. Accordingly, some embodiments include manganese in amounts of
at least 0.4%. However, manganese is an austenite former and affects the
stabilization of the ferrite phase. If the amount of manganese exceeds about
1.5%, the stabilization and formability of the steel can be affected.
[0020] Carbon is present in the ferritic stainless steel in an amount of
up to 0.02%. In
some embodiments, the carbon content is < 0.02%. In still other embodiments,
it
is 0.0054-0.0133%.
[0021] Chromium is present in some embodiments of the ferritic stainless
steels in an
amount of 15-20%. If chromium is greater than about 25%, the formability of
the
steel can be reduced.
[0022] In some embodiments, oxygen is present in the steel in an amount
<100 ppm.
When a steel melt is prepared sequentially in an argon oxygen decarburization
refining vessel and a ladle metallurgy furnace alloying vessel, oxygen in the
melt
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can be within the range of 10-60 ppm thereby providing a very clean steel
having
small titanium oxide inclusions that aid in forming the nucleation sites
responsible
for the fine as-cast equiaxed grain structure.
[0023] Sulfur is present in the ferritic stainless steel in an amount of
<0.01%.
[0024] Phosphorus can deteriorate formability in hot rolling and can
cause pitting. It is
present in the ferritic stainless steel in an amount of <0.05%.
[0025] Like manganese, nickel is an austenite former and affects the
stabilization of the
ferrite phase. Accordingly, in some embodiments, nickel is limited to <1.0%.
In
some embodiments, nickel is present in amounts of 0.13- 0.19%.
[0026] Molybdenum also improves corrosion resistance. Some embodiments
include
3.0% or less molybdenum. Some embodiments include 0.03 ¨ 0.049%
molybdenum.
[0027] For some applications, it may be desirable to include boron in the
steels of the
present invention in an amount of < 0.010%. In some embodiments, boron is
present in an amount of 0.0001 ¨ 0.002%. Boron can improve the resistance to
secondary work embrittlement of steel so that the steel sheet will be less
likely to
split during deep drawing applications and multi-step forming applications.
[0028] In some embodiments, the ferritic stainless steels may also
include other elements
known in the art of steelmaking that can be made either as deliberate
additions or
present as residual elements, i.e., impurities from steelmaking process.
EXAMPLE 1
[0029] Embodiments of the ferritic stainless steels and comparative
reference steels were
made with the compositions set forth in Table 1 below.
[0030] The materials identified as "Lab Materials" were processed on
laboratory
equipment according to the following parameters. Each ingot was reheated to a
temperature of 2300 F (1260 C). It was hot rolled to a strip thickness of
0.200"
(5.08 mm). It was then hot band annealed at a temperature of 1825-1975 C (996 -
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1079 C). It was then cold rolled to a thickness of 0.079 ¨ 0.098" (2.0 ¨
2.5mm).
The cold rolled strip was final annealed to a temperature of 1885 - 1950 F
(1029 -
1066 C).
[0031] The materials identified as "Plant Material" were processed on
production
equipment in the plant according to the following parameters. Each slab was
reheated to a temperature of 2273 - 2296 F (1245 - 1258 C). It was then hot
rolled to a strip thickness of 0.200 ¨ 0.180" (5.08 ¨4.57 mm). Except where
indicated in the examples below, the hot rolled strip was then hot band
annealed
to a temperature of 1950 - 2000 F (1066 - 1083 C). After cold rolling to 0.079
¨
0.059" (2.0¨ 1.5 mm), the strip was final annealed to a temperature of 1900-
2000 F (1038 - 1093 C).
8
Table 1 Chemical compositions in weight %.
ID Description Al B C Cb Cr Cu Mn Mo N
Ni P S Si Ti V Remarks
0
V3924 Lab Material .007 <.0005 .0090 .40 16.70 1.27
1.00 .048 .019 .16 .031 .0016 1.27 .14 .071
Invention
V3925 Lab Material .009 <.0005 .0054 .43 16.98 1.31
1.00 .049 .012 .16 .033 .0014 1.33 .21 .074
Invention
V3926 Lab Material .010 <.0005 .0077 .43 16.90 1.28
1.00 .048 .012 .16 .031 .0016 1.31 .25 .080
Invention
V3929 Lab Material .014 <.0005 .0094 .40 16.56 1.26
.98 .048 .014 .15 .030 .0015 1.28 .17 .073
Invention
V3954 Lab Material .006 .0020 .014 .30 16.99 1.27
.99 .048 .012 .14 .027 .0016 1.33 .16 .008
Invention
V3955 Lab Material .010 <.0005 .0085 .28 17.06 1.23
.99 .049 .0082 .14 .028 .0016 1.35 .16 .082
Invention
V3956 Lab Material .016 <.0005 .0089 .39 16.92 1.23
.99 .048 .0087 .14 .026 .0017 1.32 .17 .078
Invention
V3957 Lab Material .015 .0017 .0084 .41 16.90 1.28
.99 .048 .0084 .14 .026 .0016 1.32 .17 .075
Invention
V3958 Lab Material .016 .0017 .0090 .40 16.93 1.24
.99 .048 .0076 .14 .027 .0017 1.32 .16 .078
Invention
00
V3959 Lab Material .009 .0020 .0082 .31 17.35 1.27
.99 .049 .0077 .13 .026 .0018 1.31 .15 .078
Invention
V3960 Lab Material .007 .0007 .0085 .37 17.40 1.27
.99 .048 .0086 .14 .026 .0017 1.33 .16 .078
Invention
V3961 Lab Material .008 <.0005 .013 .29 16.95 1.28
.99 .048 .011 .14 .025 .0016 1.32 .16 .074
Invention
V3962 Lab Material .009 .0019 .0093 .30 16.93 1.28
.99 .048 .0082 .14 .026 .0016 1.33 .17 .078
Invention
HT #920097 Plant Material .010 .0001 .0114 .33 17.01
1.16 .98 .030 .009 .19 .026 .0015 1.30 .18 .098
Invention
HT #930354 Plant material .007 .0009 .0133 .33 17.02
1.29 .97 .030 .0095 .15 .025 .0003 1.33 .15 .096
Invention
V3918 Lab Material .012 <.0005 .012 .44 16.78 1.28
.28 .048 .010 .16 .031 .0015 .58 .21 .076 Reference
V3920 Lab Material .012 <.0005 .011 .46 16.88 1.28
.28 .049 .010 .16 .031 .0017 .94 .25 .076
Reference 1-3
V3921 Lab Material .012 <.0005 .0081 .45 16.82 1.28
.28 .049 .010 .16 .030 .0015 1.34 .27 .078
Reference
V3922 Lab Material .009 <.0005 .0084 .32 16.86 1.28
.28 .048 .010 .16 .030 .0014 1.32 .27 .080
Reference
HT #831187
Plant Material .009 .0060 .010 .17 17.58 .09 .35
1.90 .0114 .23 .022 .0005 .44 .20 .066 Reference
(444)
HT #830843
Plant Material .010 .0002 .0086 .37 14.32 .08 1.01
.010 .0077 .14 .022 .0010 1.27 .25 .045 Reference
(15 Cr-Cb)
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[0032] The materials identified as "Invention" in the remarks are
embodiments of the
terrific stainless steels of the present disclosure. The materials identified
as
"Reference" are not embodiments of the ferritic stainless steels of the
present
disclosure. In fact, two are well-known prior products: HT #831187 is Type 444
stainless steel and HT #830843 is 15 CrCb stainless steel, which is a product
of
AK Steel Corporation, West Chester, Ohio.
EXAMPLE 2
[0033] The oxidation resistance of several of several of the steel
compositions described
in Example 1 and Table 1 above was tested at 930 C for 200 hours in air. The
results of the tests are set forth in Table 2 below. The individual
compositions are
each identified by their respective ID number. The oxidation resistance was
evaluated using two factors. One was the amount of weight gain, and the other
was degree of spalling. For each material, except HT #920097, the reported
weight gain value is an average of two tests. For HT #920097, eight samples
were tested and the minimum, average, and maximum of these eight tests has
been reported.
Table 2 Oxidation resistance test results at 930 C for 200 hours in air.
Chemical Composition (weight %)
Weight Gain Spalling (Scale 0
Remarks
C Cb Cr Cu Mn N Si Ti
(mg/cm2) Off) n.)
=
1--,
..
.6.
V3954 .014 .30 16.99 1.27 .99 .012 1.33
.16 1.34 No Invention -1
o
V3924 .0090
.40 16.70 1.27 1.00 .019 1.27 .14 1.40 No Invention o
o
1--,
V3929 .0094
.40 16.56 1.26 .98 .014 1.28 .17 1.44 No Invention
V3956 .0089 .39 16.92 1.23 .99 .0087
1.32 .17 1.14 Partial* Invention
V3955 .0085 .28 17.06 1.23 .99 .0082
1.35 .16 1.15 Partial* Invention
V3961 .013 .29 16.95 1.28 .99 .011 1.32
.16 1.17 Partial* Invention
V3960 .0085 .37 17.40 1.27 .99 .0086
1.33 .16 1.19 Partial* Invention
..
V3958 .0090 .40 16.93 1.24 .99 .0076
1.32 .16 1.20 Partial* Invention P
r.,
V3957 .0084 .41 16.90 1.28 .99 .0084
1.32 .17 1.21 Partial* Invention 00 0,
r.,
1--, V3959 .0082 .31 17.35 1.27 .99 .0077
1.31 .15 1.22 Partial* Invention ,
1--,
r.,
V3962 .0093 .30 16.93 1.28 .99 .0082
1.33 .17 1.37 Partial* Invention ,
,
r.,
1
V3925 .0054 .43 16.98 1.31 1.00 .012 1.33
.21 1.43 Partial* Invention ,
...]
V3926 .0077 .43 16.90 1.28 1.00 .012 1.31
.25 1.47 Partial* Invention
1.63 Min
HT #920097 .0114 .33 17.01 1.16 .98 .009 1.30
.18 1.70 Ave No Invention
1.74 Max
V3918 .012 .44 16.78 1.28 .28 .010 .58
.21 -0.14 Severe Reference
V3920 .011 .46 16.88 1.28 .28 .010 .94
.25 -1.77 Very Sever Reference
IV
V3922 .0084 .32 16.86 1.28 .28 .010 1.32
.27 -1.98 Very Sever Reference n
,-i
V3921 .0081 .45 16.82 1.28 .28 .010 1.34
.27 -2.48 Very Sever Reference cp
n.)
o
444 .010 .17 17.58 .09 .35 .0114 .44
.20 0.88 Severe Reference 1--,
-1
15 Cr-Cb .0086 14.32 .08 1.01 .0077 1.27
.25 1.29 Severe Reference un
o
o
* - "Partial" means that spalling occurred just around the edges of the
specimens and a few small spots away from the edges. o
o
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EXAMPLE 3
[0034] The longitudinal high temperature tensile properties of several of
the steel
compositions of Example 1 were tested according to the procedure of ASTM
Standard E21 tensile test. The results of these tests are set forth below:
12
Table 3 Longitudinal high temperature tensile properties. (ASTM Standard E21
tensile tests).
600 *C 700 C
800 C
Average
ID
.2% YS at Th Remarks
Gauge .2% YS UTS Gauge .2% YS UTS
Gauge .2% YS UTS 0
ree Tern p.
(mm) (MPa) (MPa) (mm) (MPa) (MPa)
(mm) (MPa) (MPa) r.)
o
1-)
4A
V3924 2.03 260 372 2.00 116 126 2.03
37.2 46.9 138 Invention -a-,
c7,
_
V3925 2.01 241 391 2.05 151 160 2.01
41.0 50.6 144 Invention
1-)
V3926 2.00 265 385 2.03 142 150 2.00
39.3 49.6 149 Invention
V3929 2.01 262 381 2.01 125 135 2.01
37.9 48.9 141 Invention
V3954 2.02 244 348 2.04 135 165 2.03
24.1 35.1 134 Invention
V3955 2.04 239 352 2.05 147 178 2.06
32.0 44.1 139 Invention
V3956 2.05 245 354 2.06 134 150 2.05
40.7 49.3 140 Invention
V3957 2.05 257 376 2.05 100 122 2.06
38.6 50.0 132 Invention P
03
03
V3958 2.02 246 369 2.04 107 121 2.04
40.0 50.0 131 Invention
r.)
µ,.
(A) V3959 2.03 238 352 2.05 96 120 2.05
34.5 45.8 123 Invention r.)
1-
u,
1
V3960 2.03 252 370 2.05 102 118 2.05
36.9 49.3 130 Invention .
r.)
,
V3961 2.02 244 353 2.03 160 185 2.03
31.0 43.1 145 Invention 1-
...]
V3962 2.03 243 356 2.04 108 126 2.05
34.8 46.2 129 Invention
HT #920097 CL
2.00 247 373 2.00 148 167 2.01 36.6 46.9 144
Invention
#F06626 ,
HT #920097 CL
2.03 256 373 2.03 144 172 2.02 38.0 47.6 146
Invention
#F06629
,
V3918 2.01 245 370 2.02 153 166 2.02
40.0 51.3 146 Reference IV
n
V3920 2.02 251 382 1.99 167 195 2.02
38.9 49.6 152 Reference
ci)
r.)
V3921 2.01 260 383 2.00 137 151 2.00
36.5 47.5 145 Reference o
1-)
(A)
V3922 2.05 247 373 2.03 146 154 2.04
40.3 49.3 144 Reference -a-,
u,
c7,
,4z
,4z
,4z
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EXAMPLE 4
[0035] The longitudinal tensile properties of several of the steel
compositions of
Example 1 were tested according to the procedure of ASTM Standard E8/E8M.
In addition, the stretch-r values were tested according to the procedure of
ASTM
Standard E517. Ridging resistance of the compositions was also determined on a
qualitative scale of 0-6, where 0 is the best and 6 is unacceptable. The
results of
these tests are set forth below:
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Table 4 Longitudinal tensile properties (ASTM E8/E8M), stretch r-values, and
ridging resistances.
Longitudinal ASTM Tensile
Stretch r- Ridging
Lab ID HRB Remarks
Gauge .2% YS UTS EL bar (0-6)
(mm) (MPa) (MPa) (%)
2.02 475 613 27.5 93.0 3
V3926 1.01 Invention
2.02 476 614 27.7 92.8 2
2.02 465 598 27.6 92.4 2
V3925 1.21 Invention
2.02 466 600 28.6 92.0 2
2.03 432 563 31.4 89.8 1
V3929 1.37 Invention
2.03 430 563 31.4 89.6 2
2.05 451 579 29.9 90.5 2
V3924 1.24 Invention
2.04 452 580 30.0 89.9 1
2.01 425 552 31.2 88.0
V3955 1.16 1 Invention
2.02 422 547 30.5 88.2
. .
2.01 411 542 31.3 87.7
V3956 0.98 1 Invention
2.02 407 538 30.4 87.5
2.05 449 572 29.0 89.8
V3961 1.31 1 Invention
2.04 443 569 29.4 90.0
2.04 447 571 28.8 90.4
V3954 1.16 1 Invention
2.04 446 570 29.0 89.6
2.07 451 580 28.8 90.5
V3962 1.29 1 Invention
2.07 , 451 577 30.1 90.0
2.01 454 587 27.1 91.6
V3957 1.16 1 Invention
2.01 448 581 28.7 90.8
2.05 428 570 27.9 89.2
V3958 1.14 1 Invention
2.05 , 429 569 29.5 89.1
2.07 461 585 28.0 90.9
V3959 1.19 1 Invention
2.07 459 583 28.7 90.2
2.06 458 586 29.1 90.5
V3960 1.15 1 Invention
2.06 452 581 28.8 90.7
1.99 379 508 33.4 84.9 1
V3918 1.45 Reference
1.99 381 510 33.5 84.8 1
2.05 426 556 30.5 89.4 1
V3920 1.13 Reference
2.05 424 555 31.1 89.3 1
2.02 477 618 26.9 92.7 2
V3921 1.04
Reference
2.02 474 616 26.5 92.4 3
2.04 416 543 33.1 88.4 1
V3922 1.21 Reference
2.03 414 543 32.4 88.2 1
CA 02882361 2015-02-17
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EXAMPLE 5
[0036] The longitudinal tensile properties of several of the steel
compositions of
Example 1 were tested according to the procedure of ASTM Standard E8/E8M
test. In addition, the stretch-r values were tested according to the procedure
of
ASTM Standard E517. Ridging resistance of the compositions was also
determined on a qualitative scale of 0-6, where 0 is the best and 6 is
unacceptable.
The results of these tests are set forth below:
Table 5 Longitudinal tensile properties (ASTM E8/E8111), stretch r-values, and
ridging resistances.
Longitudinal ASTM Tensile
HT #920097
Coil ID Ridging
Remarks
Position
Gauge .2% YS UTS EL HRB r-bar (0-6)
(mm) (MPa) (MPa) (%)
2.01 403 534 33.1 86.3 0
681730-02
1.22
Invention
Head
2.01 404 535 32.6 86.2 0
1.97 402 532 32.8 86.4 0
681730-02
1.24
Invention
Tail
1.97 402 532 32.6 86.3 0
2.03 400 530 32.4 86.0 0
681730-05
1.37
Invention
Head
2.03 398 529 32.7 86.2 0
2.03 404 534 32.7 86.4 0
681730-05
1,20
Invention
Tail
2.03 404 534 33.8 86.6 0
1.51 405 537 31.8 86.4 0
681727-02
1.34
Invention
Head 1.51 406 537 31.0 86.4 0
1.61 401 530 32.6 86.0 0
681727-02
1.31
Invention
Tail
1.61 401 530 32.3 86.3 0
1.53 398 530 31.8 85.8 0
681727-01A
1.38
Invention
Head 1.53 401 532 32.1 86.0 0
1.56 401 532 31.7 86.2 0
681727-01A
1.34
Invention
Tail
1.56 401 532 32.5 85.9 0
16
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EXAMPLE 6
[0037] Four hot band samples of A, B, C, and D from heat #920097 were
produced in the
plant. A laboratory study was conducted in order to examine the effect of hot
band
annealing process and the hot band annealing temperatures for higher r-bar
(drawability or drawing capability), the results of which are set forth in
Table 6.
Lower hot band annealing temperature and processing without hot band annealing
resulted in higher r-bar with slightly lower tensile elongation and lower
resistance to
ridging, but all within an acceptable range.
Table 6 - Longitudinal tensile properties (ASTM E8/E8M), stretch r-values, and
ridging resistances.
Longitudinal ASTM Tensile
Lab ID 1-IBA Temp r-bar Remarks
Gauge .2% YS UTS EL (0-6)
HRB Ridging
(mm) (MPa) (MPa) (%)
2.01 412 543 31.4 86.5
Al No HBA 1.44 1 Invention
2.01 413 543 31.7 87.0
1.99 407 538 31.7 86.6
A2 1825 F 1.20 0 Invention
1.99 407 537 31.7 87.2
1.97 407 537 32.2 86.7
A3 1900 F 1.15 0 Invention
1.97 407 537 32.1 86.8
1.97 406 536 32.0 86.8
A4 1975 F 1.15 0 Invention
1.97 405 536 32.2 86.8
2.02 414 541 31.9 86.8
B1 No HBA 1.29 1 Invention
2.02 413 541 31.3 86.4
1.99 409 538 33.2 87.2
B2 1825 F 1.24 0 Invention
1.99 408 539 32.5 85.0
1.98 408 537 32.9 85.6
B3 1900 F 1.19 0 Invention
1.98 407 536 31.7 86.4
1.98 406 536 32.8 85.7
B4 1975 F 1.25 0 Invention
1.99 405 535 32.1 86.5
1.51 419 556 29.3 86.6
Cl No NBA 1.70 1 Invention
1.50 418 556 29.4 86.4
1.50 414 545 30.8 86.7
C2 1825 F 1.61 0 Invention
1.50 412 545 31.1 85.7
17
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1.49 407 541 31.3 86.0
C3 1900 F 1.45 0 Invention
1.49 410 541 30.4 85.9
1.49 410 540 31.3 85.8
C4 1975 F 1.45 0 Invention
1.49 409 540 31.1 86.0
1.55 418 548 29.1 86.7
D1 No HBA 1.57 1 Invention
1.55 419 549 29.6 86.6
1.53 411 541 31.0 86.2
D2 1825 F 1.48 1 Invention
1.53 413 543 31.4 85.8
1.54 413 538 31.0 86.4
D3 1900 F 1.33 o Invention
1.53 416 543 30.6 86.2
1.52 410 539 31.4 86.6
04 1975 F 1.32 0 Invention
1.54 408 536 32.1 86.3
18
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EXAMPLE 7
[0038] One plant produced hot band coil with the composition set forth in
Table 1 (HT
#930354, CL #681158-03) was finish-processed without hot band annealing to 1.5
mm gauge. When a hot band annealing step was included, the plant-produced
coils
of HT#930354 resulted in r-bar values of 1.34, 1.31, 1.38, and 1.34, as shown
in
Table 5. When the hot band annealing step was not included, it resulted in
higher r-
bar of 1.46, as shown by Table 7 below.
Table 7 - Longitudinal tensile properties (ASTM E8/E8M), stretch r-values, and
ridging resistances.
Longitudinal ASTM Tensile
Plant ID HBA
Remarks
Gauge .2% YS UTS EL (0-6)
HRB r-bar Ridging
(mm) (MPa) (MPa) (%)
1.55 439 565 27.4 89.9 2
HT# 930354 CL#
No __________________________________________________ 1.46
Invention
682158-03
1.55 441 566 28.4 89.5 2
[0039] It will be understood various modifications may be made to this
invention without
departing from the spirit and scope of it. Therefore, the limits of this
invention
should be determined from the appended claims.
19
