	US 12,454,744 B2
	Method for producing a steel part and corresponding steel part
Bernard Resiak, Saulny (FR)
Assigned to ArcelorMittal, Luxembourg (LU)
Appl. No. 16/613,712
Filed by ArcelorMittal, Luxembourg (LU)
PCT Filed May 22, 2018, PCT No. PCT/IB2018/053598 § 371(c)(1), (2) Date Nov. 14, 2019, PCT Pub. No. WO2018/215923, PCT Pub. Date Nov. 29, 2018.
Claims priority of application No. PCT/IB2017/053004 (WO), filed on May 22, 2017.
Prior Publication US 2020/0385847 A1, Dec. 10, 2020
Int. Cl. C22C 38/00 (2006.01); C21D 8/02 (2006.01); C21D 8/06 (2006.01); C22C 38/02 (2006.01); C22C 38/06 (2006.01); C22C 38/44 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01); C22C 38/54 (2006.01); C22C 38/58 (2006.01)

CPC C22C 38/54 (2013.01) [C21D 8/0263 (2013.01); C21D 8/065 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/06 (2013.01); C22C 38/44 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C21D 2211/001 (2013.01); C21D 2211/002 (2013.01); C21D 2211/008 (2013.01); C22C 38/58 (2013.01)]

31 Claims

2. A hot rolled steel part having a composition comprising, by weight:

0.10%≤C≤0.35%

0.8%≤Si≤2.0%

1.8%≤Mn≤2.5%

P≤0.1%

0%≤S≤0.4%

0%≤Al≤1.0%

N≤0.015%

0%≤Mo≤0.4%

0.02%≤Nb≤0.08%

0.02%≤Ti≤0.05%

0.001%≤B≤0.005%

0.5%≤Cr≤1.8%

0%≤V≤0.5%

0%≤Ni≤0.5%

a remainder being Fe and unavoidable impurities resulting from smelting,

the hot rolled steel part having a microstructure consisting, in surface fraction, of 70% to 90% of bainite, 5% to 25% of M/A compounds and at most 25% of martensite, the bainite and the M/A compounds containing retained austenite such that a total content of retained austenite in the hot rolled steel part is comprised between 5% and 25% and a carbon content of the retained austenite being comprised between 0.8% and 1.5% by weight,

the hot rolled steel part being a solid bar having a diameter between 25 mm and 100 mm or a wire with a diameter between 5 mm and 35 mm.