Abstract: A method for producing a coated steel sheet having a tensile strength TS of at least 1100 MPa, a total elongation TE according to ISO standard 6892-1 of at least 12%, the product TSxTE of the tensile strength by the total elongation being at least 14200 MPa %, and a hole expansion ratio HER according to ISO standard 16630:2009 of at least 25%, the method including the following successive steps: providing a cold-rolled steel sheet, the chemical composition of the steel containing in weight %: 0.15%?C?0.23%, 2.0%?Mn?2.7%, with C+Mn/10?0.420%, 0?Cr?0.40%, with Mn+Cr?2.25%, 0.2%?Si?1.6%, 0.02%?Al?1.2%, with 1.0%?Si+Al?2.2%, 0?Nb?0.035%, 0?Mo?0.1%, the remainder being Fe and unavoidable impurities, annealing the steel sheet at an annealing temperature TA so as to obtain a structure comprising at least 65% of austenite and at most 35% of intercritical ferrite, quenching the sheet from a temperature of at least 600° C. at a cooling rate comprised between 20° C./s and 50° C.

Abstract: A method for producing a coated steel sheet having a tensile strength TS of at least 1100 MPa, a total elongation TE according to ISO standard 6892-1 of at least 12%, the product TS×TE of the tensile strength by the total elongation being at least 14200 MPa %, and a hole expansion ratio HER according to ISO standard 16630:2009 of at least 25%, the method including the following successive steps: providing a cold-rolled steel sheet, the chemical composition of the steel containing in weight %: 0.15%?C?0.23%, 2.0%?Mn?2.7%, with C+Mn/10?0.420%, 0?Cr?0.40%, with Mn+Cr?2.25%, 0.2%?Si?1.6%, 0.02%?Al?1.2%, with 1.0%?Si+Al?2.2%, 0?Nb?0.035%?Mo?0.1%, the remainder being Fe and unavoidable impurities, annealing the steel sheet at an annealing temperature TA so as to obtain a structure comprising at least 65% of austenite and at most 35% of intercritical ferrite, quenching the sheet from a temperature of at least 600° C. at a cooling rate comprised between 20° C./s and 50° C.

Abstract: A method for producing a coated steel sheet having a tensile strength TS of at least 1100 MPa, a total elongation TE according to ISO standard 6892-1 of at least 12%, the product TSxTE of the tensile strength by the total elongation being at least 14200 MPa %, and a hole expansion ratio HER according to ISO standard 16630:2009 of at least 25%, the method including the following successive steps: providing a cold-rolled steel sheet, the chemical composition of the steel containing in weight %: 0.15%?C?0.23%, 2.0%?Mn?2.7%, with C+Mn/10?0.420%, 0?Cr?0.40%, with Mn+Cr?2.25%, 0.2%?Si?1.6%, 0.02%?Al?1.2%, with 1.0%?Si+Al?2.2%, 0?Nb?0.035%, 0?Mo?0.1%, the remainder being Fe and unavoidable impurities, annealing the steel sheet at an annealing temperature TA so as to obtain a structure comprising at least 65% of austenite and at most 35% of intercritical ferrite, quenching the sheet from a temperature of at least 600° C. at a cooling rate comprised between 20° C./s and 50° C.

Abstract: A method for producing a steel sheet is provided. The method includes providing a cold-rolled steel sheet including in weight %: 0.15%?C?0.23%, 1.4%?Mn?2.6%, 0.6%?Si?1.5%, 0.02%?Al?1.0%, with 1.0%?Si+Al?2.0%, 0?Nb?0.035%, 0?Mo?0.3%, 0?Cr?0.3%, and a remainder of Fe and unavoidable impurities, annealing the steel sheet at an annealing temperature between Ac1 and Ac3 to obtaining at least 40% austenite and at least 40% intercritical ferrite, quenching the sheet from at least 600° C. at a cooling rate of at least 20° C./s to a quenching temperature between 180° C. and 260° C., heating the sheet to a partitioning temperature between 375° C. and 470° C. and maintaining the sheet at this partitioning temperature for a partitioning time Pt between 25 s and 440 s, then cooling the sheet to room temperature. A steel sheet is also provided.

Abstract: A method for producing a steel sheet, the method containing the following successive steps: providing a cold-rolled steel sheet, the chemical composition of the steel containing in weight %: 0.15%?C?0.23%, 2.0%?Mn?2.8%, 1.0%?Si?2.1%, 0.02%?Al?1.0%, with 1.7%?Si+Al?2.1%, 0?Nb?0.035%, 0?Mo?0.3%, 0?Cr?0.4%, the remainder being Fe and unavoidable impurities, annealing the steel sheet at an annealing temperature TA so as to obtain a structure comprising at least 65% of austenite and up to 35% of intercritical ferrite, quenching the sheet at a cooling rate of at least 20° C./s from a temperature of at least 600° C. down to a quenching temperature QT comprised between Ms-170° C. and Ms-80° C., heating the sheet up to a partitioning temperature PT between 350° C. and 450° C.