| 摘要 |
This case hardening steel material has a composition that contains, in mass %, 0.05 to 0.45% of C, 0.01 to 1.0% of Si, more than 0 to 2.0% of Mn, 0.001 to 0.06% of Al, 0.002 to 0.03% of N, more than 0 to 0.1% of S and more than 0 to 0.05% of P with the balance being Fe and unavoidable impurities. In the case hardening steel material, the equi-axed crystal region satisfies the relationships (1) and (2), or the columnar crystal region satisfies the relationship (3). Re = (Ae/Ao) × 100 <= 30% (1) (Cmin, 1/Co) >= 0.95 (2) (Cmin, 2/Co) >= 0.95 (3) |
