35CrMoA钢激光淬火-渗氮复合处理微观组织与性能

Microstructure and Properties of 35CrMoA Steel in Laser Quenching-Nitriding

对35CrMoA钢进行激光淬火-渗氮复合处理,采用光学显微镜(OM)、X射线衍射仪(XRD)、透射电镜(TEM)、显微硬度计及磨擦磨损试验研究了激光淬火/渗氮层的显微组织、硬度及耐磨性能,并与气体渗氮层对比。结果表明,两种渗氮层均由ε相,γ′相,Cr2N相及Fe3C组成。激光淬火/渗氮白亮层中-εFe3N含量较高,而脆硬的-ζFe2N相及Fe2O3含量较低,且Cr2N颗粒细小。扩散层中γ-′Fe4N中存在超点阵结构,Fe原子和N原子在γ′相中有序排列,γ′相和-αFe相存在一定的位向关系,二者的共格性和相容性优良,细小渗碳体分布在条状下贝氏体组织中。激光淬火/渗氮试样的磨损表面划痕较浅,而气体渗氮试样表面有较深的犁沟,局部区域存在剥落,激光淬火/渗氮复合处理使渗氮层深度增加,硬度提高,耐磨性增强。

Laser quenching and nitriding treatment are performed on 35CrMoA steel,and the microstructure,hardness and wear resistance of laser quenching/nitrided layer were investigated by means of optical microscope（OM）,X-ray diffractomer（XRD）,transmission electron microscope（TEM）,microhardness tester and wear equipment compared with the gas nitrided layers.The results show that,both nitrided layer consist of ε,γ′,Cr2N and Fe3C.The content of ε-Fe3N is higher in the laser quenching/nitrided white layer while the contents of the brittle ζ-Fe2N and Fe2O3 are lower than that of the gas nitrided layer,and the Cr2N particles are much finer.The ultra lattice structure exist in γ′-Fe4N in the diffusion layer,in which the Fe and N atom arrange orderly.There are phase relation,coherence and compatibility between γ′-Fe4N and α-Fe.Spherical particles of cementite are formed in lower strip bainite.The scratch in worn surface of laser quenching/nitrided layer is shallow,but the gas nitriding worn surface has deep plow furrow and flaking.After laser quenching/nitriding treatment,the depth of the nitrided layer increases,and hardness as well as wear resistance are improved dramatically.