| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat treatment method for a steel member including a quenching stage where, even in the case of a steel member such as a large-sized die, its toughening can be securely performed, and strain and cracks are hardly caused therein. SOLUTION: The heat treatment method for a steel member includes a quenching stage where a steel member which contains at least 0.20 to 1.5 wt.% carbon and 0.5 to 25 wt.% carbide forming element(s) and is composed of a tool steel having a weight of≥50 kg is subjected to the following cooling steps: the first cooling step where cooling is performed in a high temperature zone ht from a quenching temperature (1,030°C) to 600°C at the average cooling velocity Cl of >3°C/min in which the precipitation of a pearlite phase and a ferrite phase can be evaded; and the second cooling step where cooling is performed in a low temperature zone 1t from 500 to 130°C at the average cooling velocity of≥1°C/min. COPYRIGHT: (C)2007,JPO&INPIT
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