Patent ID: 10066281

Abstract:
An age-hardenable steel having a composition consisting of: C: 0.05 to 0.20%, Si: 0.01 to 0.50%, Mn: 1.5 to 2.5%, S: 0.005 to 0.08%, Cr: more than 0.50% and not more than 1.6%, Al: 0.005 to 0.05%, V: 0.25 to 0.50%, Mo: 0 to 1.0%, Cu: 0 to 0.3%, Ni: 0 to 0.3%, Ca: 0 to 0.005%, and Bi: 0 to 0.4%, the balance being Fe and impurities. Within the impurities, P≤0.03%, Ti<0.005%, and N<0.0080%, and [C+0.3Mn+0.25Cr+0.6Mo≥0.68], [C+0.1Si+0.2Mn+0.15Cr+0.35V+0.2Mo≤1.05], and [−4.5C+Mn+Cr−3.5V−0.8Mo≥0.12]. The steel has hardness before aging of not more than 310 HV. After aging, the fatigue strength is not less than 480 MPa and absorbed energy at 20° C. is not less than 12 J.