Hai-nan Zhang, Jian-bo Yu, Zhi-gang Yang, Jin-tao Jiang, Ying Dong, Xiao-xin Zhang, Jiang Wang, Zhong-ming Ren
Journal of Iron and Steel Research International. 2025, 32(5): 1226-1244.
A novel plasma torch nitriding technology was applied for the first time to improve the surface properties of M2 high-speed steel by adjusting different experimental parameters. The nitrogen content, precipitate, microstructure, mechanical prop-erty, and corrosion resistance of the nitrided layer were comprehensively analyzed using an ONH analyzer, scanning electron microscope (SEM), micro-area X-ray diffractometer, transmission electron microscope (TEM), Vickers micro-hardness tester, high-temperature wear tester, 3D profilometer, tensile testing machine, and electrochemical workstation. The research results show that the novel plasma torch nitriding technology can achieve synergistic strengthening of nitrogen, carbon, and alloying element solid solution, precipitation strengthening, and martensitic structure on the surface of M2 high-speed steel. The nitrogen content on the specimen surface increased up to 0.17%, while the size and area of carbides were reduced by 89% and 86%, respectively, indicating a transformation towards fine nitrogen-rich precipitates. Compared to the original M2 steel, the nitrided specimens exhibited significant improvements in overall performance. The hardness increased from 228 HV0.2 to a maximum of 795 HV0.2, the wear coefficient decreased from a maximum of 0.8 to 0.49, the tensile strength increased from 753 MPa to a maximum of 934 MPa, and the corrosion current density decreased from 1.2 9 10-5 to a minimum of 1.9 9 10-6A/cm2.
