Steel part having high strength and high bendability
OwnerSebastian COBO, Matthieu SALIBinventors
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Abstract
Steel part having a chemical composition including, by weight %, 0.18≤C≤0.27, 0.18≤Si≤0.30, 1.0≤Mn≤1.5, 0.14≤Cr≤0.25, 0.02≤Al≤0.06, 0.02≤Ti≤0.06, 0.0020≤B≤0.0040, 0≤S≤0.008, 0.008≤N≤0.020, the remainder of the composition being iron and unavoidable impurities resulting from the elaboration process, having a microstructure including, in surface fraction, 95% or more of martensite, wherein the surface fraction of TiN particles in the skin portion is equal to or greater than 200*10−6 inclusions/mm2 and the average equivalent diameter of the TiN particles in the skin portion is equal to or smaller than 2.0 microns.
Claims16
A steel part having a chemical composition comprising, by weight %:
- 0.18
- ≤
- C
- ≤
- 0.27
- 0.18
- ≤
- Si
- ≤
- 0.3
- 1.
- ≤
- Mn
- ≤
- 1.5
- 0.14
- ≤
- Cr
- ≤
- 0.25
- 0.02
- ≤
- Al
- ≤
- 0.06
- 0.02
- ≤
- Ti
- ≤
- 0.06
- 0.0015
- ≤
- B
- ≤
- 0.004
- 0
- ≤
- S
- ≤
- 0.005
- 0
- ≤
- P
- ≤
- 0.04
- 0.008
- %
- ≤
- N
- ≤
- 0.02
- 0
- ≤
- Mo
- ≤
- 0.3
- 0
- ≤
- Nb
- ≤
- 0.1
- 0
- ≤
- V
- ≤
- 0.3
- 0
- ≤
- Cu
- ≤
- 0.25
- 0
- ≤
- Ni
- ≤
- 0.25
- 0
- ≤
- Sn
- ≤
- 0.05
- 0
- ≤
- As
- ≤
- 0.03
- 0
- ≤
- Sb
- ≤
- 0.03
- ,
- a remainder of the composition being iron and unavoidable impurities resulting from processing;
- and
- a microstructure comprising, in surface fraction, 95% or more of martensite, the microstructure optionally including bainite, ferrite and/or retained austenite;
- the steel part comprising a bulk portion occupying a centermost 80% of its thickness and a first skin defined by an outermost 10% of the thickness on a first side of the bulk portion, and a second skin defined by an outermost 10% of the thickness on a second side of the bulk portion,
- wherein a surface fraction of TiN particles in the first skin is equal to or greater than 200*10−6 inclusions/mm2.
Dependencies are inferred from the claim text.