| 摘要 |
This heat-treated steel material has a chemical composition that contains, in mass%, 0.16-0.38% of C, 0.6-1.5% of Mn, 0.4-2.0% of Cr, 0.01-0.10% of Ti, 0.001-0.010% of B, 0.20% or less of Si, 0.05% or less of P, 0.05% or less of S, 0.01% or less of N, 0-2.0% of Ni, 0-1.0% of Cu, 0-1.0% of Mo, 0-1.0% of V, 0-1.0% of Al, 0-1.0% of Nb and 0-0.1% of REM, with the balance made up of Fe and impurities. This heat-treated steel material has a structure that comprises 1.5% by volume or less of residual austenite, with the balance made up of martensite. |
