Effect of rare earth nitriding on QPQ salt bath composite treatment performance of 9Cr18Mo steel

doi:10.13251/j.issn.0254-6051.2024.03.011

Abstract

Abstract: In order to further improve the performance of 9Cr18Mo steel, the Quench-Polish-Quench (QPQ) rare earth nitriding agent was composed of self-made nitriding base salt as nitriding agent, potassium nitrate as oxidizing agent, lanthanum carbonate, yttrium carbonate and cerium carbonate as rare earth accelerator, and then the QPQ salt bath composite treatment was carried out for the 9Cr18Mo steel at 610 ℃. The effects of rare earth on the microstructure and properties of the 9Cr18Mo steel were studied by means of SEM, EDS, XRD, microhardness test, electrochemical performance test and wear resistance test. The results show that the surface of the QPQ salt bath composite treated specimen is mainly composed of oxide layer, nitriding layer and diffusion layer. The main component phases are Fe₄N, CrN, α_N, Fe_2-3N, Li₂Fe₃O₄ and Fe₃O₄. Compared with that without rare earth addition, the addition of rare earth on the QPQ salt bath composite treatment can increase the microhardness by 90 HV0.2 on average, and also improve the corrosion resistance and wear resistance.

Key words: 9Cr18Mo steel, rare earth nitriding, QPQ treatment, corrosion resistance, wear resistance, microhardness

CLC Number:

TG161

Zhang Xin, Meng Zhengbing, Zhou Ying, Chen Yuanyu, Li Yuxiang. Effect of rare earth nitriding on QPQ salt bath composite treatment performance of 9Cr18Mo steel[J]. Heat Treatment of Metals, 2024, 49(3): 63-67.

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