| 摘要 |
PROBLEM TO BE SOLVED: To provide a hardening treatment method by a high-temperature vacuum nitriding method, in which it is made possible to improve the production rate of products by improving a nitrogen adsorption rate while making wear resistance and surface hardness maximum and making an amount of deformation minimum while taking advantage of low-grade materials. SOLUTION: The method includes a process P10 of heating a workpiece by heating the inside of a heating chamber to 350 to 500°C; a process P20 of putting oxygen into the heating chamber to activate the surface of the workpiece; a process P30 of raising the internal temperature of the heating chamber to≥700°C, and putting gaseous ammonia into the heating chamber to subject the workpiece to nitriding treatment; a process P40 of moving the workpiece subjected to the nitriding treatment into a cooling chamber, controlling the pressure in the cooling chamber and uniformly cooling the workpiece with the oil within an oil quenching chamber while controlling the agitating rate in the oil quenching chamber; and a process P50 of lifting the workpiece cooled in the oil quenching chamber and uniformly cooling the workpiece in the gaseous atmosphere of the vaporized oil. COPYRIGHT: (C)2009,JPO&INPIT
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