Abstract: A method for the manufacture of a TWIP steel is provided including: (A) feeding of a slab comprising by weight: 0.5<C<1.2%, 13.0?Mn<25.0%, S?0.030%, P?0.080%, N?0.1%, Si?3.0%, 0.051%?Al?4.0%, 0.1?V?2.5%, and on a purely optional basis, one or more of Nb?0.5%, B?0.005%, Cr?1.0%, Mo?0.40%, Ni?1.0%, Cu?5.0%, Ti?0.5%, 0.06?Sn?0.2%, the remainder of the composition being made of iron and inevitable impurities resulting from the elaboration, (B) reheating the slab and hot rolling the slab to provide a hot rolled slab, (C) coiling the hot rolled slab to provide a coiled slab, (D) first cold-rolling the coiled slab to provide a first cold rolled slab, (E) recrystallization annealing the first cold rolled slab such that an annealed steel sheet having an UTSannealed is obtained and (F) second cold-rolling the annealed steel sheet with a reduction rate CR % that satisfies the following equation A: 1216.472?0.98795*UTSannealed?(?0.0008*UTSannealed+1.0124)*CR %2+(0.0371*UTSannealed?29.583)*CR %.

Abstract: The invention relates to a hot-rolled steel sheet having a tensile strength of greater than 1200 MPa, an Re/Rm ratio of less than 0.75 and an elongation at break of greater than 10%, the composition of which contains, the contents being expressed by weight: 0.10%?C?0.25%; 1%?Mn?3%; Al?0.015%; Si?1.985%; Mo?0.30%; Cr?1.5%; S?0.015%; P?0.1%; Co?1.5%; B?0.005%; it being understood that 1%?Si+Al?2%; Cr+(3×Mo)?0.3%, the balance of the composition consisting of iron and inevitable impurities resulting from the smelting, the microstructure of the steel consisting of at least 75% bainite, residual austenite in an amount equal to or greater than 5% and martensite in an amount equal to or greater than 2%.

Abstract: A method for the manufacture of a TWIP steel is provided including: (A) feeding of a slab comprising by weight: 0.5<C<1.2%, 13.0?Mn<25.0%, S?0.030%, P?0.080%, N?0.1%, Si?3.0%, 0.051%?Al?4.0%, 0.1?V?2.5%, and on a purely optional basis, one or more of Nb?0.5%, ?B?0.005%, Cr?1.0%, Mo?0.40%, Ni?1.0%, Cu?5.0%, Ti?0.5%, 0.06?Sn?0.2%, the remainder of the composition being made of iron and inevitable impurities resulting from the elaboration, (B) reheating the slab and hot rolling the slab to provide a hot rolled slab, (C) coiling the hot rolled slab to provide a coiled slab, (D) first cold-rolling the coiled slab to provide a first cold rolled slab, (E) recrystallization annealing the first cold rolled slab such that an annealed steel sheet having an UTSannealed is obtained and (F) second cold-rolling the annealed steel sheet with a reduction rate CR % that satisfies the following equation A: 1216.472?0.98795*UTSannealed?(?0.0008*UTSannealed+1.0124)*CR %2+(0.0371*UTSannealed?29.583)*CR %.

Abstract: The invention relates to the manufacture of a cold-rolled steel sheet having a strength of more than 900 MPa, an elastic limit of more than 700 MPa and distributed elongation of more than 12%, the composition of which includes, the contents being expressed as weight percentages: 0.26%?C?0.45%, 1.0%?Mn?3.0%, 1.0%?Si?3.0%, Al?0.10%, 0%?Cr?1.5%, S?0.005%, P?0.020%, Nb?0.1%, Ti?0.020%, V?0.015%, N?0.01%, the remainder of the composition being iron and inevitable impurities resulting from the production process. The microstructure, given in surface proportions, comprises 13% to 25% residual austenite and 13% to 30% MA islands, the remainder consisting of bainite and possibly ferrite.

Abstract: The invention relates to a hot-rolled steel sheet having a tensile strength of greater than 1200 MPa, an Re/Rm ratio of less than 0.75 and an elongation at break of greater than 10%, the composition of which contains, the contents being expressed by weight: 0.10%?C?0.25%; 1%?Mn?3%; Al?0.015%; Si?1.985%; Mo?0.30%; Cr?1.5%; S?0.015%; P?0.1%; Co?1.5%; B?0.005%; it being understood that 1%?Si+Al?2%; Cr +(3×Mo)?0.3%, the balance of the composition consisting of iron and inevitable impurities resulting from the smelting, the microstructure of the steel consisting of at least 75% bainite, residual austenite in an amount equal to or greater than 5% and martensite in an amount equal to or greater than 2%.

Abstract: The invention relates to a hot-rolled steel sheet having a tensile strength of greater than 1200 MPa, an Re/Rm ratio of less than 0.75 and an elongation at break of greater than 10%, the composition of which contains, the contents being expressed by weight: 0.10%?C?0.25%; 1%?Mn?3%; Al?0.015%; Si?1.985%; Mo?0.30%; Cr?1.5%; S?0.015%; P?0.1%; Co?1.5%; B?0.005%; it being understood that 1%?Si+Al?2%; Cr+(3×Mo)?0.3%, the balance of the composition consisting of iron and inevitable impurities resulting from the smelting, the microstructure of the steel consisting of at least 75% bainite, residual austenite in an amount equal to or greater than 5% and martensite in an amount equal to or greater than 2%.

Abstract: The present invention provides a cold rolled steel sheet. The steel sheet has a strength greater than 1000 MPa, a uniform elongation greater than 12% and a V-bendability greater than 90°. The composition of the steel sheet includes, expressed in per cent by weight, 0.15%?C?0.25%, 1.8%?Mn?3.0%, 1.2%?Si?2%, 0%?Al?0.10%, 0%?Cr?0.50%, 0%?Cu?1%, 0%?Ni?1%, 0%?S?0.005%, 0%?P?0.020%, Nb?0.015%, Ti?0.020%, V?0.015%, Co?1%, N?0.008%, B?0.001% whereby Mn+Ni+Cu?3%. The remainder of the composition consists of iron and inevitable impurities resulting from processing. The microstructure includes, in area percentage, 5 to 20% polygonal ferrite, 10 to 15% residual austenite, 5 to 15% martensite and a balance of bainite. The bainite is in the form of laths and includes carbides between the laths. A number N of inter-lath carbides larger than 0.1 micrometers per unit of surface area is less than or equal to 50000/mm2. A fabrication method and a motor vehicle are also provided.

Abstract: The invention relates to the manufacture of a cold-rolled steel sheet having a strength of more than 900 MPa, an elastic limit of more than 700 MPa and distributed elongation of more than 12%, the composition of which includes, the contents being expressed as weight percentages: 0.26%?C?0.45%, 1.0%?Mn?3.0%, 1.0%?Si?3.0%, Al?0.10%, 0%?Cr?1.5% %, S?0.005%, P?0.020%, Nb?0.1%, Ti?0.020%, V?0.015%, N?0.01%, the remainder of the composition being iron and inevitable impurities resulting from the production process. The microstructure, given in surface proportions, comprises 13% to 25% residual austenite and 13% to 30% MA islands, the remainder consisting of bainite and possibly ferrite.

Abstract: The present invention provides a cold rolled steel sheet. The steel sheet has a strength greater than 1000 MPa, a uniform elongation greater than 12% and a V-bendability greater than 90°. The composition of the steel sheet includes, expressed in per cent by weight, 0.15%?C?0.25%, 1.8%?Mn?3.0%, 1.2%?Si?2%, 0%?Al?0.10%, 0%?Cr?0.50%, 0%?Cu?1%, 0%?Ni?1%, 0%?S?0.005%, 0%?P?0.020%, Nb?0.015%, Ti?0.020%, V?0.015%, Co?1%, N?0.008%, B?0.001% whereby Mn+Ni+Cu?3%. The remainder of the composition consists of iron and inevitable impurities resulting from processing. The microstructure includes, in area percentage, 5 to 20% polygonal ferrite, 10 to 15% residual austenite, 5 to 15% martensite and a balance of bainite. The bainite is in the form of laths and includes carbides between the laths. A number N of inter-lath carbides larger than 0.1 micrometers per unit of surface area is less than or equal to 50000/mm2. A fabrication method and a motor vehicle are also provided.

Abstract: The invention relates to a hot-rolled steel sheet having a tensile strength of greater than 1200 MPa, an Re/Rm ratio of less than 0.75 and an elongation at break of greater than 10%, the composition of which contains, the contents being expressed by weight: 0.10%?C?0.25%; 1%?Mn?3%; Al?0.015%; Si?1.985%; Mo?0.30%; Cr?1.5%; S?0.015%; P?0.1%; Co?1.5%; B?0.005%; it being understood that 1%?Si+Al?2%; Cr+(3×Mo)?0.3%, the balance of the composition consisting of iron and inevitable impurities resulting from the smelting, the microstructure of the steel consisting of at least 75% bainite, residual austenite in an amount equal to or greater than 5% and martensite in an amount equal to or greater than 2%.