8620钢的真空低压渗碳热处理工艺

Vacuum low-pressure carburizing heat treatment process of AISI 8620 steel

采用真空低压渗碳工艺,在WZST-60G双室真空渗碳设备上进行8620钢的真空热处理工艺研究,从渗碳均匀性的角度对其显微组织、硬度、有效硬化层深度等重要工艺指标进行分析,获得了能够应用于实际生产的8620钢热处理工艺。8620钢在930℃渗碳,825℃油淬后进行-70℃深冷处理90 min,然后进行170℃回火处理后,其表面残留奥氏体等级为1级,表面硬度为57~60 HRC,有效硬化层深度在0.7~0.8 mm,同炉次有效硬化层深度偏差小于0.1 mm,渗碳均匀性较好,符合产品工艺要求。

The heat treatment technology of 8620 steel was studied on WZST-60G double-chamber vacuum carburizing equipment by using vacuum low-pressure carburizing process.The important technological indexes such as microstructure,hardness and effective hardened depth were analyzed from the perspective of carburizing uniformity.The results show that after being carburized at 930℃,oil quenched at 825℃,then deep-cooled at-70℃for 90 min,and tempered at 170℃,the 8620 steel fully meets the technical requirements.The surface retained austenite is 1st grade,the surface hardness is 57-60 HRC,and the effective hardened depth is 0.7-0.8 mm,and the variance of effective hardening depth in the same furnace is less than 0.1 mm.It is concluded that the uniformity of carburization is fairly good,which meets the technological requirements of the products.