Fabrication of steel components used for production of sub-frame components involves cutting a piece from a steel strip with a given composition, reheating the piece above its austenitizing temperature and anvil tempering

摘要

Fabrication of flat components of tempered steel comprises: cutting a piece from a strip of steel with a given composition, reheating the piece at a temperature greater than the austenitizing temperature and placing the piece between two flat tools and anvil tempering. The fabrication of flat components of tempered steel with a tensile strength greater than 1100 MPa and an excellent flatness consists of: (a) cutting a piece from a strip with a thickness of less than 7 mm of steel with a given composition; (b) subjecting the piece to a reheating operation at a temperature greater than the austenitizing temperature; (c) transferring the piece between two flat tools to realize an anvil tempering by contact with the tools during the cooling phase, the contact being prolonged until the temperature is less than or equal to 100 deg C. The steel used has the following chemical composition (by wt. %): (a) 0.1 = carbon (C) = 0.5; (b) 0.5 = manganese (Mn) = 3; (c) 0.001 = silicon (Si) = 0.5; (d) sulfur (S) = 0.05; (e) phosphorus (P) = 0.1; (f) chromium (Cr) = 1; (g) aluminum (Al) = 0.1; (h) 0.0005 = boron (B) = 0.008; (i) titanium (Ti) = 0.2; (j) calcium (Ca) = 0.005; (k) zirconium (Zr) = 0.005; (l) the remainder being iron (Fe) and inevitable production impurities; and (m) the titanium/nitrogen (Ti/N) ratio is greater than 3.42.