| 摘要 |
Power transmission shaft consists of an induction surface hardened carbon steel of specified composition. A power transmission shaft consists of an induction hardened carbon steel which has a hardening ratio (effective hardened layer depth divided by the shaft radius) of 0.25-0.50 and which has the composition (by wt.) 0.39-0.49% C, 0.4-1.5% Si, 0.4-1.0% Mn, <= 0.025% S, <= 0.02% P, 0.01-0.1% Al, balance Fe and impurities. Independent claims are also included for the following: (i) a constant-velocity joint including the above shaft having a residual surface compressive stress of >= 100 kgf/mm<2> achieved by hammering; and (ii) a power transmission shaft having an induction hardened smooth surface portion and an induction hardened toothed torque transmission portion, the effective hardened layer depth of the minimum diameter region of the smooth surface portion being greater than that of the minimum diameter region of the toothed torque transmission portion. |
