Plasma nitriding process to improve the hardness of the secondary nitrided layer

Abstract

The present invention relates to the technical field of nitriding process, and in particular to a plasma nitriding process for improving the hardness of a secondary surface nitriding layer, wherein the nitriding is divided into three sections of heat preservation: one section of heat preservation is maintained at a temperature of 470°C for 3 hours, while the ammonia flow rate is controlled at 0.6 L / min, the pressure in the furnace is controlled at 240-260 Pa, and the voltage is controlled at 680 V; the second section of heat preservation is maintained at a temperature of 500°C for 5 hours, while the ammonia flow rate is controlled at 1.0 L / min, the pressure in the furnace is controlled at 300-320 Pa, and the voltage is controlled at 700 V; the third section of heat preservation is maintained at a temperature of 520°C for 10 hours, while the ammonia flow rate is controlled at 1.9 L / min, the pressure in the furnace is controlled at 380-400 Pa, and the voltage is controlled at 730 V. The plasma nitriding process for improving the hardness of a secondary surface nitriding layer provided by the present invention can improve the hardness of the secondary surface nitriding layer, obtain parts with a surface hardness of HV≥800 after grinding the nitriding layer, and improve the wear resistance and corrosion resistance of such products during operation.

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