Patent ID: 10538823

Abstract:
A high-strength steel sheet has a chemical composition comprising C: 0.05-0.20%, Si: 0.02-3.0%, Mn: 0.5-3.0%, P: at most 0.5%, S: at most 0.05%, Cr: 0.05-1.0%, sol. Al: 0.01-1.0%, one or more elements selected from the group consisting of Ti, Nb, Mo, V, and W: a total of 0.002-0.03%, and a remainder of Fe and impurities. The sheet has an average grain diameter of ferrite of at most 3.0 μm at least in a region of 100-200 μm in the sheet thickness direction from the surface of the steel sheet. The average spacing in the sheet thickness direction of the remaining structure in this region is at most 3.0 μm. Mechanical properties include at least 750 MPa tensile strength and at least 13,000 MPa·% (tensile strength×elongation).