渗碳轴承钢G20CrNi2MoA的硫氮碳共渗工艺

Sulphonitrocarburizing process of G20CrNi2MoA carburizing bearing steel

以渗碳轴承钢G20Cr Ni2Mo A为研究对象,在570、580、600℃温度下对其退火态试样进行硫氮碳共渗,并进行淬火和低温回火处理,通过扫描电镜对其渗层及心部组织进行分析,并用显微硬度计对渗层进行了硬度分析。结果表明：580℃共渗后组织均匀细密、心部硬度较高;与一次淬火＋低温回火相比,二次淬火＋低温回火得到的晶粒尺寸更为细小,得到的渗层组织分布更为均匀且致密,表层为硫氮碳化合物,心部组织为回火马氏体。硫化物的存在可起到减小摩擦和具有一定自润滑的作用,增加轴承抗磨损能力,提高轴承寿命。

G20CrNi2MoA carburizing bearing steel annealed samples were sulphonitrocarburized at 570,580 and 600 ℃,respectively. And twice quenching and low temperature tempering were conducted. Microstructure of the modified layer and core in the G20CrNi2MoA steel are observed by means of scanning electron microscope. The hardness of the layer for the steel is measured by a microhardness tester. The results show that the steel can attain higher hardness in core with uniform microstructure after 580 ℃ sulphonitrocarburizing heat treatment. The grain size of the steel by twice quenching and low temperature tempering is finer than that of once quench and low temperature temper. After twice quenching and low temperature tempering treatment,sulfur nitrogen carbon compounds in the surface,and tempered martensite in the core is attained and the distribution of structures for the layer is uniform. The presence of sulfide can reduce friction and have a selflubrication effect,which can improve the wear resistance and prolong the life of bearing.