Hardening heat treatment manner and hardening of the cast iron component after heating the cast iron

摘要

PROBLEM TO BE SOLVED: To provide a hardening heat-treatment method for a cast iron member, which obtains a uniform pearlite structure having predetermined hardness, improves fatigue resistance, abrasion resistance and permanent set resistance while securing machinability, in addition, continuously treats the member with high-frequency heating, and efficiently heat-treat only a part necessary to be treated in a short time, and to provide a hardening-heat-treated cast iron member.;SOLUTION: This hardening heat-treatment method comprises heating a cast iron member having graphite to an austenitizing temperature T1 of 950 to 1,050°C by high-frequency heating, then cooling it to a temperature T2 of 500°C or lower at a cooling rate V of 20°C/sec or higher, sequentially reheating it to a temperature T3 of 550 to 700°C by high-frequency heating, and then cooling it to obtain the uniform pearlite structure having Vickers hardness at a treated part in a range of 200 to 500.;COPYRIGHT: (C)2004,JPO