残余奥氏体含量对马氏体高强钢滑动磨损性能的影响

对3种不同残奥(RA)含量的马氏体高强钢进行干滑动摩擦磨损试验, 研究RA含量对其磨损性能的影响. 利用扫描电镜、透射电镜、X射线衍射仪等对试验后的磨损表面及横截面显微组织进行表征. 结果表明, RA含量越高, 磨损表面越光滑, 摩擦系数和磨损率越小, 也即马氏体高强钢的耐磨性越好. 磨损引起的大应变使RA发生应变诱导马氏体相变, 导致硬度和硬化层厚度显著增大. RA含量最高的HT3试样的硬度提高了18.3%, 硬化层厚度达70μm. 相比RA含量低的试样, HT3试样表现出很好的耐磨性. 这是因为马氏体相变使硬度逐步增加, 抗裂纹萌生能力提高; 同时由于亚表面良好的韧性, 可延缓和阻止裂纹扩展, 使得点蚀和剥落不易形成. 因此, 要提高马氏体高强钢的耐磨性, 除了硬度要求外, 还需要考虑其亚表面韧性.

Effect of retained austenite content on sliding wear properties of high-strength martensite steel

To investigate the effect of retained austenite (RA) content on wear resistance, dry sliding wear tests were carried out on high strength martensite steels of three different RA contents. The wear surface properties and microstructures of cross sections were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-Ray Diffraction (XRD) and microhardness tester. The results show that the higher the RA content, the smoother the wear surface and the smaller the coefficient of friction and wear rate, i.e. the better wear resistance. The large plastic deformation by sliding wear triggers strain-induced martensite transformation, which leads to increasing in hardness and hardened layer. The hardness of the HT3 sample, with the highest RA content, is increased by 18.3% and the hardened layer reaches to 70μm. In comparison with the samples of lower RA contents, HT3 presents the best wear resistance. This is due to the increased hardness caused by martensite transformation and good ductility in the subsurface, which can delay and stop crack growth, and thus is less likely to form pit and spalling. Therefore, it is suggested that apart from the hardness requirement, the subsurface ductility should be considered for the improvement of the wear resistance.