采用OM、TEM和XRD对深层渗碳处理后H13钢的显微组织进行观测,研究了深层渗碳对H13钢显微组织和硬度的影响.结果表明:渗碳后完全退火试样与渗碳后球化退火试样的渗碳层厚度均在3 mm以上,组织细密均匀,硬度提高30％～60％;渗碳后球化退火试样的晶粒更细小,基体上碳化物弥散分布并存在较多的亚结构,且表面硬度稍高于渗碳后完全退火试样.最佳深层渗碳处理工艺为1000℃下固体渗碳4h,接着进行球化退火(840℃保温4h,炉冷到740℃再保温4h,炉冷到500℃后空冷到室温),然后进行1030℃淬火10 min,最后进行560℃回火2次,每次2h.
Microstructure of H13 steel after deep carburizing were studied by means of OM,TEM and XRD,and the effect of deep carburization on its hardness and microstructure was studied.The results show that after deep carburizing,the thickness of the carburizing layer of the steel is more than 3 mm,having refined microstructure,and the hardness of the steel increases by 30％-60％.After spheroidizing annealing,finer crystal grains,dispersive carbides and more sub-structures distributed in the matrix are obtained,and the carburizing sample exhibits slightly higher surface hardness than that of the full annealing sample.Therefore,the optimum deep carburization process in this work is solid carburizing at 1000 ℃ for 4 h,and then spheroidizing annealing at 840 ℃ for 4 h,furnace cooling to 740 ℃ for 4 h,furnace cooling to 500 ℃,air cooling to room temperature,and then oil quenching at 1030 ℃ for 10 min,finally tempering at 560 ℃ for twice,each for 2 h.
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