| 摘要 |
PURPOSE:To improve the hardenability of a member when the member is heat treated by water cooling, by forming an oxide film on the surface of the member so as to increase the efficiency of water cooling and by heat treating the member by water cooling. CONSTITUTION:A steel member is heated in an oxidizing atmosphere or heated in a heating furnace, taken out of the furnace and allowed to cool in the air to form an oxide film on the surface. The heat transfer rate of the surface of the steel member is considerably increased by the oxide film. The steel member is then water-cooled to carry out heat treatment.
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