PURPOSE: To prevent the coarsening of crystalline grains at the time of induction hardening and to inhibit the occurrence of quenching crack by increasing residual compressive stress in the surface layer and properly controlling the amounts of carbonitride forming elements, such as Al, and the amount of N.
CONSTITUTION: A steel which has a composition containing, by weight ratio, 0.55-0.75% C, 0.01-0.50% Si, 0.5-2.00% Mn, 0.01-0.10% S, 0.015-0.05% l, and 0.010-0.020% N, or further containing one or ≥2 kinds among ≤1.5% Cr, ≤3.5% Ni, and ≤1.0% Mo, or further containing one or ≥2 kinds among 0.005-0.04% Ti, 0.005-0.1% Nb, and 0.03-0.3% V, also containing P by the amount limited to ≤0.030%, and having the balance iron with inevitable impurities is used. This method is a method for producing shaft-shaped induction hardened parts characterized by forming the above steel into the prescribed shaft shape, successively performing induction hardening and tempering to regulate the ratio of effective hardening depth (t) to parts radius (r), t/r, to 0.4-0.7, or further exerting, after induction hardening and tempering, shot peening treatment at ≥0.5mmA arc height.
MORI TOSHIMICHI
NINOMIYA TAKASHI
