Abstract: A high strength cold rolled steel sheet has a composition consisting of the following elements (in wt. %):C 0.08-0.14, Mn 2.5-3.0, Si 0.7-1.1, Cr 0.05-0.4, optionally Al?0.2, Nb?0.1, Mo?0.1, V?0.1, Ti?0.1, Ca?0.05, Cu?0.1, Ni?0.2, B?0.005, balance Fe apart from impurities. The steel has a yield ratio ?0.72 and a bendability (Ri/t) is ?2.0. A method of manufacturing the steel sheet and an automotive structural part comprising the steel sheet also is provided.

Abstract: A cold roll strip or sheet includes in (wt %) C 0.08-0.28; Mn 1.4-4.5; Cr 0.01-0.5; Si 0.01-2.5; Al 0.01-0.6; Si+Al?0.1; Si+Al+Cr?0.4; Nb?0.008; Ti?0.02; Mo?0.08; Ca?0.005; V?0.02; balance Fe apart from impurities. The steel is within the area defined by the coordinates A, B, C, D, where Ri/t (y-axle) is plotted vs TS(MPa)/YR (x-axle), and where A is [1200, 2), B is [2000, 4], C is [2000, 3], and D is [1200, 1].

Abstract: A zinc or zinc-alloy coated rolled steel strip or sheet includes (in wt. %) 0.08-0.28 C, 1.4-4.5 Mn, 0.01-0.5 Cr, 0.01-2.5 Si, 0.01-2.0 Al. The steel has a tensile strength of 950-1550 MPa, a yield strength of 350-1400 MPa, a yield ratio?0.35, and Ri/t?4. The microstructure includes ?40 tempered martensite+bainite, ?30 fresh martensite, 5-20 retained austenite, and ?35 polygonal ferrite. The hydrogen concentration is less than 0.2 ppm in the steel.

Abstract: A zinc or zinc-alloy coated rolled steel strip or sheet includes 0.08-0.28 C, 1.4-4.5 Mn, 0.01-0.5 Cr, 0.01-2.5 Si, 0.01-0.6 Al. The steel has a tensile strength of 950-1550 MPa, yield strength of 550-1400 MPa, yield ratio ?0.50, and Ri/t?4. The microstructure has ?70 tempered martensite+bainite, ?10 fresh martensite, 2-20 retained austenite, and ?20 polygonal ferrite. The steel has a decarburized zone where the C content at a depth of 20 ?m is not more than 75% of the carbon content in the middle of the steel strip and/or the microhardness at a depth of 20 ?m is not higher than 75% of the microhardness in the middle of the steel strip. The adhesion of the zinc or zinc alloy coating is 1 or 2 according to SEP 1931.

Abstract: A high strength cold rolled steel sheet has a composition consisting of the following elements (in wt. %): C 0.07-0.15, Mn 2.3-3.2, Si 0.6-1.2, Cr 0.05-0.5, Al?0.2 Nb?0.1, balance Fe apart from impurities, a multiphase microstructure comprising a matrix of bainitic ferrite, and a tensile strength (Rm) of 980-1100 MPa.