| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a non-conditioned steel for hot forging having improved machinability and hardness variation while maintaining strength equivalent to conventional V addition non-conditioned steels without relaying on adding the large amount of V.SOLUTION: There are provided a non-conditioned steel for saving V-type hot forging excellent in machinability and fatigue strength and having small hardness variation, containing, by mass%, C:0.45 to 0.60%, Si:1.00 to 1.50%, Mn:0.70 to 0.95%, S:0.030% to 0.100%, Cr:0 to 0.70%, Al:0.010 to 0.050% and V:0 to 0.10% with satisfying the formula 1 (C+0.7Si+0.6Mn+0.3Cr+5 V≥1.70) and the formula 2 (5Mn+2Cr+15 V≤5.70) and the balance Fe with inevitable impurities, and a hot forged non-conditioned component manufactured by using the same. It is preferable to cool the steel in a temperature range of 700 to 600°C at average cooling speed of 10 to 100°C/minute after forging during hot forging of the steel.</p> |
