Abstract: Steel sheet suitable for a multistep hot stamping process and associated manufacturing process, the steel sheet having a composition including, by weight percent: C: 0.13-0.4%, Mn: 0.4-4.2%, Si: 0.1-2.5%, Cr?2%, Mo?0.65%, Nb?0.1%, Al?3.0%, Ti?0.1%, B?0.005%, P?0.025%, S?0.01%, N?0.01%, Ni?2.0%, Ca?0.1%, W?0.30%, V?0.1%, Cu?0.2%, wherein Q is less than 20, the factor Q being defined as (the elements are expressed in weight percent): Q=114?68*C?18*Mn+20*Si?56*Cr?61*Ni?37*Al+39*Mo+79*Nb?17691*B, the steel sheet having a microstructure including, in surface fraction, from 60% to 100% of recrystallized ferrite, less than 40% of the sum of martensite, bainite and carbides and less than 5% of non-recrystallized ferrite.

Abstract: A coated steel sheet and press hardened steel part having a composition including, by weight percent: C 0.15-0.25%, Mn 0.5-1.8%, Si 0.1-1.25%, Al 0.01-0.1%, Cr 0.1-1.0%, Ti 0.01-0.1%, B 0.001-0.004%, P?0.020%, S?0.010%, N?0.010% the remainder of the composition being iron and unavoidable impurities resulting from the smelting. The press hardened steel part includes a bulk having a microstructure including, in surface fraction, more than 95% of martensite and less than 5% of bainite, a coating layer at the surface of the steel part, a ferritic interdiffusion layer between the coating layer and the bulk, and a ratio between the ferritic grain width in the interdiffusion layer GWint over prior austenite grain size in the bulk PAGSbulk, satisfying following equation (GWint/PAGSbulk)?1?30%.

Abstract: A coated steel sheet and press hardened steel part having a composition including, by weight percent: C 0.15-0.25%, Mn 0.5-1.8%, Si 0.1-1.25%, Al 0.01-0.1%, Cr 0.1-1.0%, Ti 0.01-0.1%, B 0.001-0.004%, P?0.020%, S?0.010%, N?0.010% the remainder of the composition being iron and unavoidable impurities resulting from the smelting. The press hardened steel part includes a bulk having a microstructure including, in surface fraction, more than 95% of martensite and less than 5% of bainite, a coating layer at the surface of the steel part, a ferritic interdiffusion layer between the coating layer and the bulk, and a ratio between the ferritic grain width in the interdiffusion layer GWint over prior austenite grain size in the bulk PAGSbulk, satisfying following equation (GWint/PAGSbulk)?1?30%.

Abstract: Steel sheet suitable for a multistep hot stamping process and associated manufacturing process, the steel sheet having a composition including, by weight percent: C: 0.13-0.4%, Mn: 0.4-4.2%, Si: 0.1-2.5%, Cr?2%, Mo?0.65%, Nb?0.1%, Al?3.0%, Ti?0.1%, B?0.005%, P?0.025%, S?0.01%, N?0.01%, Ni?2.0%, Ca?0.1%, W?0.30%, V?0.1%, Cu?0.2%, wherein Q is less than 20, the factor Q being defined as (the elements are expressed in weight percent): Q=114?68*C?18*Mn+20*Si?56*Cr?61*Ni?37*Al+39*Mo+79*Nb?17691*B, the steel sheet having a microstructure including, in surface fraction, from 60% to 100% of recrystallized ferrite, less than 40% of the sum of martensite, bainite and carbides and less than 5% of non-recrystallized ferrite.

Abstract: A coated steel sheet and press hardened steel part having a composition including, by weight percent: C 0.15-0.25%, Mn 0.5-1.8%, Si 0.1-1.25%, Al 0.01-0.1%, Cr 0.1-1.0%, Ti 0.01-0.1%, B 0.001-0.004%, P?0.020%, S?0.010%, N?0.010% the remainder of the composition being iron and unavoidable impurities resulting from the smelting. The press hardened steel part includes a bulk having a microstructure including, in surface fraction, more than 95% of martensite and less than 5% of bainite, a coating layer at the surface of the steel part, a ferritic interdiffusion layer between the coating layer and the bulk, and a ratio between the ferritic grain width in the interdiffusion layer GWint over prior austenite grain size in the bulk PAGSbulk, satisfying following equation (GWint/PAGSbulk)?1?30%.