Abstract: A coated dual-phase steel and process for producing the coated dual-phase steel is provided. The process includes providing a steel slab with a desired chemistry, soaking the slab at an elevated temperature and then hot rolling the slab to produce hot-rolled strip. The hot-rolled strip is coiled and has a ferrite-pearlite microstructure. The coiled hot-rolled strip is cold-rolled into cold-rolled sheet with at least a 60% reduction in thickness compared to the thickness of the coiled hot-rolled strip. The cold-rolled sheet is subjected to an intercritical anneal followed by rapid cooling with the absence of an isothermal heat treatment or hold after rapid cooling near the molten metal pot temperature—during which, before or after which the steel is coated. The coated steel sheet has a dual-phase ferrite-martensite microstructure, a yield strength of at least 310 MPa, a tensile strength of at least 580 MPa and a total elongation to failure of at least 18%.

Abstract: A process for manufacturing a cold rolled high strength dual phase steel. The process includes soaking a steel slab within a temperature range of 1200-1300° C., hot rolling the soaked steel slab in a roughing treatment and producing a transfer bar, and hot rolling the transfer bar in a finishing treatment and producing hot rolled strip. The hot rolled strip is cold rolled with at least a 55% reduction in thickness. The cold rolled sheet is intercritically annealed at a temperature between 790-840° C. and rapidly cooled to a temperature between 450-500° C. The rapidly cooled sheet has a ferrite plus martensite microstructure, a 0.2% yield strength of at least 550 MPa, a tensile strength of at least 980 MPa and a total elongation to failure of at least 10%.

Abstract: Dual-phase steels and a process for producing a family of dual-phase steels that have a low YS/TS ratio and tensile strength above 590 MPa. The process includes employing low annealing temperatures combined with specific cooling strategies using gas jet rapid cooling equipped with “Ultra Rapid Cooling” (URC) capacity in the cooling tower. The process can also include the production of dual-phase steels with tensile strengths of at least 690 MPa by processing steels with specific cooling strategies using the URC having a refined Mo content towards the higher end of the chemical composition range mentioned in the current stated invention.

Abstract: A silicon alloyed steel for hot rolling and a process of hot rolling the silicon alloyed steel is provided. The process includes providing a steel slab having a chemical composition in weight percent within a range of 0.06-0.30 C, 0.3-2.0 Mn, 0.6-3.5 Si, and Fe plus incidental melting impurities. The steel slab is hot rolled and hot rolled steel strip is produced. The hot rolled steel strip is coiled at temperatures between 100-600° C. and has a microstructure containing at least 90 vol % ferrite plus pearlite, a yield strength of at least 400 megapascals (MPa), a tensile strength of at least 600 MPa, and a tensile elongation of at least 20%.

Abstract: A low carbon-high manganese steel sheet and process for manufacturing the sheet is provided. The process includes soaking a steel slab with a desired chemical composition within a temperature range of 1200-1350° C., followed by hot rolling of the slab into hot strip. The cold rolled sheet is continuously annealed within a temperature range of 730-850° C. and temper rolled between 1.0-2.0%. The temper rolled sheet has a yield strength greater than 280 megapascals (MPa), a tensile strength greater than 400 MPa, an elongation to fracture greater than 30%, an n-value greater than 0.15, and a bakehard index between 15-35 MPa.

Abstract: A process for manufacturing hot rolled high strength dual phase steels. In some instances, hot rolled strip is continuously cooled to less than 100° C. prior to coiling using a cooling rate between 40-70° C./second. In other instances, hot rolled strip is cooled to less than 100° C. prior to coiling using a step cooling treatment. In yet other instances, hot rolled strip is continuously cooled to less than 100° C. prior to coiling using a cooling rate between 70-100° C./second. For hot rolled strip subjected to a cooling rate between 40-70° C./second, or subjected to the step cooling treatment, hot rolled steel sheet with a tensile strength greater than 590 MPa is produced. For hot rolled strip subjected to a cooling rate between 70-100° C./second, hot rolled steel sheet with a tensile strength greater than 690 MPa is produced. Also, the hot rolled steel sheet has a ferrite plus martensite microstructure free of pearlite and bainite.

Abstract: A process for manufacturing a cold rolled high strength dual phase steel. The process includes soaking a steel slab within a temperature range of 1200-1300° C., hot rolling the soaked steel slab in a roughing treatment and producing a transfer bar, and hot rolling the transfer bar in a finishing treatment and producing hot rolled strip. The hot rolled strip is cold rolled with at least a 55% reduction in thickness. The cold rolled sheet is intercritically annealed at a temperature between 790-840 ° C. and rapidly cooled to a temperature between 450-500 ° C. The rapidly cooled sheet has a ferrite plus martensite microstructure, a 0.2% yield strength of at least 550 MPa, a tensile strength of at least 980 MPa and a total elongation to failure of at least 10%.

Abstract: A coated dual-phase steel and process for producing the coated dual-phase steel is provided. The process includes providing a steel slab with a desired chemistry, soaking the slab at an elevated temperature and then hot rolling the slab to produce hot-rolled strip. The hot-rolled strip is coiled and has a ferrite-pearlite microstructure. The coiled hot-rolled strip is cold-rolled into cold-rolled sheet with at least a 60% reduction in thickness compared to the thickness of the coiled hot-rolled strip. The cold-rolled sheet is subjected to an intercritical anneal followed by rapid cooling with the absence of an isothermal heat treatment or hold after rapid cooling near the molten metal pot temperature—during which, before or after which the steel is coated. The coated steel sheet has a dual-phase ferrite-martensite microstructure, a yield strength of at least 310 MPa, a tensile strength of at least 580 MPa and a total elongation to failure of at least 18%.

Abstract: Dual-phase steels and a process for producing a family of dual-phase steels that have a low YS/TS ratio and tensile strength above 590 MPa. The process includes employing low annealing temperatures combined with specific cooling strategies using gas jet rapid cooling equipped with “Ultra Rapid Cooling” (URC) capacity in the cooling tower. The process can also include the production of dual-phase steels with tensile strengths of at least 690 MPa by processing steels with specific cooling strategies using the URC having a refined Mo content towards the higher end of the chemical composition range mentioned in the current stated invention.

Abstract: A process for manufacturing a ferritic hot rolled steel strip is provided. The process includes providing a steel slab, hot rolling the slab to produce a transfer bar and ferritic hot rolling the transfer bar to produce hot rolled strip. The ferritic hot rolled strip is coiled at temperatures between 580-780° C. and has a yield strength between 130-210 MPa, a tensile strength greater than 260 MPa, a uniform elongation greater than 15%, a total elongation to failure greater than 30%, and an n-value greater than 0.2.

Abstract: A high strength mild steel alloy is provided. In addition, a process for making the high strength steel alloy is also provided. The process includes providing a mild steel alloy with a chemical composition in weight percent within a range of 0.12-0.25 carbon, 0.30-1.70 manganese, 0.50 max silicon, 0.10 max chromium, 0.01 max niobium, 0.035 max titanium, 0.01 vanadium, 0.10 max molybdenum, 0.10 max nickel, 0.015 max sulfur, 0.025 max phosphorus, 0.012 max nitrogen, 0.003 max boron, and 0.015-0.065 aluminum. Hot rolled steel strip with a thickness of less than 10 millimeters is cold rolled to produce a cold rolled steel sheet that has a thickness that is less than 50% of the hot rolled steel strip thickness which is subsequently recovery annealed to provide sheet material having a yield strength greater than 550 megapascals (MPa) and a percent elongation to failure greater than 3.5%.