| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a steel material having improved torsion-fatigue strength, while reducing deterioration of machinability, which is made of machine structural steel to be used for power transmission components such as gears and shafts for automobiles and industrial machinery. <P>SOLUTION: The steel material made of a machine structural steel having excellent torsion-fatigue strength without causing reduction of machinability through application of carburizing, quenching and tempering shown in Figure 2 to the steel that satisfies formula (1) below. The steel includes, in mass%, 0.15-0.35% C, 0.30-0.95% Si, 0.10-1.00% Mn, ≤0.030% P, ≤0.030% S, 1.20-2.30% Cr, ≤0.30% Cu, 0.008-0.100% Al, ≤0.0030% O, 0.0020-0.0300% N and the balance being Fe and inevitable impurities. 6.0%≥2C+5Si+Cr-3Mn≥2.0% (1). <P>COPYRIGHT: (C)2013,JPO&INPIT |
