PURPOSE: To give the partially different properties by only the heat treatment, by splitting up the material to be quenched into plural parts with grooves, by heating each split part to different quenching temperature, and then, by quenching each part at the same or different cooling speed.
CONSTITUTION: The grooves 2, 2, are formed in the material 1 to be quenched, and the insulator 3 is filled up in each groove 2. Thus formed split parts, that is, the part between the grooves 2 and 2, and the part between the groove 2 and the end face 4, are heated up to respectively different temperature. Besides, the partition plate 5 is attached closely to the groove 2, and each part is independently cooled by different cooling method, that is, water cooling, air cooling, etc. Hereupon, because of the existence of the partition plate 5, each split part is prevented from cooling by the cooling medium for the adjoining part. Thus, the different parts of a monolithic product can be quenched under the different quenching conditions, and are endowed with different physical properties.
TSUCHIYA KATSUHIRO
ITOU KAZUO
FUKUDA TAKASHI
