METHOD FOR HEAT TREATMENT OF ELONGATED METAL MEMBERS BY INDUCTION HEATING

摘要

Uniform temperature distribution in an elongated metal member, for example a steel pipe, heated by induction heating by induction heating coil means is obtained by initially preheating, for a predetermined period of time, the end portions of the elongated metal member by preliminary local induction heating means, prior to overall induction heating of the elongated metal member. The invention avoids uneven temperature distribution in the elongated metal member resulting from the known V-shape heating phenomenon.