| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide steel for machine structure that has a rolling fatigue life B<SB POS="POST">10</SB>of more than 2×10<SP POS="POST">7</SP>times and a hardness HV of less than 330 without performing spheroidizing annealing treatment for softening. <P>SOLUTION: The steel for machine structure has component composition containing, by mass ratio, 0.40-0.70% of C, 0.80% or less of Si, 0.70-1.5% of Mn, 0.020% or less of P, 0.030% or less of S, 0.050% or less of Al, 0.20% or less of Cr, 0.05-0.5% of Mo, 0.0015% or less of O, 0.0050% or less of Ti (excluding 0), and 0.0015-0.010% of N, with the balance comprising Fe and unavoidable impurities, wherein the Ti content and the N content in the steel satisfies specific relation and has the rolling fatigue life (B<SB POS="POST">10</SB>) of more than 2×10<SP POS="POST">7</SP>times and the hardness (HV) of less than 330. <P>COPYRIGHT: (C)2013,JPO&INPIT |
