GCr15 and GCr15SiMn bearing steel samples were used to conduct experiment studies on different processes of carbonitriding heat treatments.Using optical microscope,X-ray diffractometer,hardness tester,and other equipment,the microstructure,hardness,austenite grain size,and other microstructure and proper-ties of the samples from different carbonitriding heat treatment processes were analyzed,and the effect of car-burizing temperature on the microstructure and properties of the carburized layer was studied.The results show that,considering the comprehensive factors of carburizing layer depth,microstructure,grain size and hard-ness,the carbonitriding temperature is controlled at 820 ℃ with the carbon potential of 1.18％,the micro-structure and properties of the samples after quenching and low temperature tempering are relatively good.Af-ter the further cryogenic treatment of the GCr15SiMn steel sample,the surface hardness of the steel is in-creased from 64.5 HRC to 66.1 HRC,and the surface residual austenite content is decreased from 22.1％to 12.5％.The cryogenic treatment reduces the residual austenite content on the surface effectively.
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