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研究了气体渗氮层和激光淬火-渗氮层的相组成、微观结构、显微硬度及脆性。结果表明,激光淬火-渗氮白亮层中ε-Fe3N含量由14.74%增至69.45%,而脆硬的ξ-Fe2N含量由79.95%降至25.03%。表层的N含量降低,渗氮层N浓度曲线降低趋势平缓,N的总扩散通量增加,渗氮层厚度增加。激光淬火-渗氮层组织晶粒细小致密,渗碳体分布在条状下贝氏体组织中,硬度高的Cr2N颗粒数目增加,白亮层显微硬度值显著提高,渗氮层脆断的临界压力由气体渗氮层的3 N提高到激光淬火-渗氮层的6 N。
The phase composition, microstructure, microhardness and brittleness of gas nitrided layer and laser quenched - nitrided layer were studied. The results show that the content of ε-Fe3N increases from 14.74% to 69.45% in laser quenching-nitriding white bright layer, while the brittle ξ-Fe2N content decreases from 79.95% to 25.03%. The N content of the surface layer decreases, the N concentration curve of nitrided layer tends to decrease gently, the total diffusion flux of N increases, and the thickness of nitrided layer increases. Laser quenching - the microstructure of nitrided layer is fine and compact, and the cementite distributes in the strip-shaped lower bainite. The number of Cr2N particles with high hardness increases, the microhardness of white layer increases significantly, and the brittle fracture of nitrided layer The pressure is raised from 3 N of the gas nitriding layer to 6 N of the laser quench-nitrided layer.