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US 2019/0218639 A1Published application
Twip steel sheet having an austenitic matrix
AssigneeArcelorMittal
InventorsColin SCOTT, Thierry IUNG, Marie-Christine THEYSSIER
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Abstract
A cold rolled and recovered TWIP steel sheet is provided having an austenitic matrix including by weight: 0.71<C<1.2%, 13.0≤Mn<25.0%, S≤0.030%, P≤0.080%, N≤0.1%, 0.1≤Si≤3.0%, 0.1≤V≤2.50%, and on a purely optional basis, one or more elements such as Cu≤5.0%, Al≤4.0%, Nb≤0.5%, B≤0.005%, Cr≤1.0%, Mo≤0.40%, Ni≤1.0%, Ti≤0.5%, 0.06≤Sn≤0.2%, the remainder of the composition being made of iron and inevitable impurities resulting from elaboration.
Claims19
1-16. (canceled)
17:
- A cold rolled and recovered TWIP steel sheet having an austenitic matrix comprising by weight:
- 0.71<C<1.2%,
- 13.0≤Mn<25.0%,
- S≤0.030%,
- P≤0.080%,
- N≤0.1%,
- 0.1≤Si≤3.0%,
- 0.1≤V≤2.50%,
- the remainder of the composition being made of iron and inevitable impurities resulting from elaboration.
6 more elements
18:
- A steel sheet according to claim 17, wherein the austenitic matrix further comprises one or more of
- Cu≤5.0%,
- Al≤4.0%,
- Nb≤0.5%,
- B≤0.005%,
- Cr≤1.0%,
- Mo≤0.40%,
- Ni≤1.0%,
- Ti≤0.5%, and/or
- 0.06≤Sn≤0.2%.
7 more elements
19:
- A steel sheet according to claim 17, wherein the amount of C is between 0.71 and 1.1%.
20:
- A steel sheet according to claim 19, wherein the amount of C is between 0.80 and 1.0%.
21:
- A steel sheet according to claim 20, wherein the amount of C is between 0.9 and 1.0%.
22:
- A steel sheet according to claim 17, wherein the amount of Cu is below 2.0%.
23:
- A steel sheet according to claim 17, wherein the amount of Si is below or equal to 0.6%.
24:
- A steel sheet according to claim 17, wherein the Al content is below or equal to 2%.
25:
- A steel sheet according to claim 17, wherein the amount of V is between 0.1 and 1.0%.
26:
- A steel sheet according to claim 17, wherein the steel sheet is covered by a metallic coating.
27:
- A steel sheet according to claim 17, wherein the steel sheet is covered by an aluminum-based coating or a zinc-based coating.
28:
- A steel sheet according to claim 27, wherein the aluminium-based coated comprises less than 15% Si, less than 5.0% Fe, optionally 0.1 to 8.0% Mg and optionally 0.1 to 30.0% Zn, the remainder being Al.
29:
- A steel sheet according to claim 27, wherein the zinc-based coating comprises 0.01-8.0% Al, optionally 0.2-8.0% Mg, the remainder being Zn.
30:
- A method for producing a TWIP steel sheet comprising:
- A. feeding a slab having a composition comprising by weight:
- 0.71<C<1.2%,
- 13.0≤Mn<25.0%,
- S≤0.030%,
- P≤0.080%,
- N≤0.1%,
- 0.1≤Si≤3.0%,
- 0.1≤V≤2.50%,
- the remainder of the composition being made of iron and inevitable impurities resulting from elaboration;
- B. Reheating the slab at a temperature above 1000° C. and hot rolling it with a final rolling temperature of at least 850° C. to provide a hot rolled slab;
- C. coiling the hot rolled slab at a temperature below or equal to 580° C. to provide a coiled slab,
- D. first cold-rolling the coiled slab with a reduction rate between 30 and 70% to provide a first cold rolled slab;
- E. recrystallization annealing the first cold rolled slab between 700 and 900° C. to provide an annealed slab;
- F. second cold-rolling the annealed slab with a reduction rate between 1 to 50% to provide a second cold rolled slab;
- and
- G. recovery heat treating the second cold rolled slab.
14 more elements
31:
- A method according to claim 30, wherein the composition further comprises one or more of
- Cu≤5.0%,
- Al≤4.0%,
- Nb≤0.5%,
- B≤0.005%,
- Cr≤1.0%,
- Mo≤0.40%,
- Ni≤1.0%,
- Ti≤0.5%, and/or
- 0.06≤Sn≤0.2%.
7 more elements
32:
- A method according to claim 30, wherein the second cold rolled slab is a steel sheet and wherein the recovery step (G) is performed by heating the steel sheet at a temperature between 390 and 700° C. in a batch annealing or a continuous annealing furnace.
33:
- A method according to claim 32, further comprising
- H. hot-dip coating the heated steel sheet.
34:
- A method according to claim 30, wherein the recovery step G) is performed by hot-dip coating.