| 摘要 |
PROBLEM TO BE SOLVED: To provide a carburization gas-quenching method which cools a workpiece that has been carburized through heating, isothermally holds it and quenches it through cooling, at high efficiency, into high quality, so as to cause little deformation due to quenching, without using a salt bath. SOLUTION: The carburization gas-quenching method includes charging the carburized workpiece into a gas-cooling furnace capable of isothermally holding the workpiece, isothermally holding it at a temperature right above a martensite transformation point of the surface of the workpiece, and then gas-quenching it at atmospheric temperature or the lower temperature, wherein the gas-cooling furnace changes a cooling rate between the temperature when the workpiece has been charged and the temperature when it is isothermally held, by changing control elements such as a pressure and quantity of a coolant gas and a control target temperature, and minutely controls the temperature so as to control the periods of time for the inside and surface of the workpiece to reach the martensite transformation point. COPYRIGHT: (C)2006,JPO&NCIPI
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