| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel being a steel for a machine structural use for a large-sized component, the steel being used after carburizing treatment or carbonitriding treatment by increasing hardenability and the steel having toughness equal to or above that of the conventional Ni-Mo-added steel and adding neither Ni nor Mo and therefore has the reduced cost. SOLUTION: The steel for carburizing or carbonitriding has a composition comprising, by mass, 0.13 to 0.33% C, 0.1 to 1.0% Si, 1.2 to 2.0% Mn,≤0.030% P,≤0.030% S, 1.8 to 3.5% Cr,≤0.050% Al and≤0.0020% O, and the balance Fe with inevitable impurities, wherein the contents of C, Si, Mn and Cr satisfy (0.04+0.35C)×(1.00+0.70Si)×(0.70+3.96Mn)×(1.0+2.16Cr)≥3.0. COPYRIGHT: (C)2011,JPO&INPIT |
