| 摘要 |
<p>A steel product for induction hardening which has a chemical composition in mass % that C: 0.3 to 0.7 %, Si: 1.1 % or less, Mn: 0.2 to 1.1 %, Mo: 0.05 to 0.6, S: 0.06 % or less, P: 0.025 % or less, Al: 0.25 % or less, Cr: 0.3 % or less and the balance: Fe and inevitable impurities, has a ferrite structure and a pearlite structure, wherein the sum of the ferrite structure and the pearlite structure accounts for 90 volume % or more of the steel product, the ferrite structure has a thickness of 30 mum or less, and a hardened layer after induction hardening has an average old austenite grain diameter of 12 mum or less. The above steel product is improved in the easiness to be machined and exhibits excellent fatigue strength, and thus is suitable for a drive shaft and a constant-velocity universal joint.</p> |
