A novel nanobainitic (NB) steel is treated by three different heat treatment routes: quenching‐tempering (QT), quenching‐austempering‐tempering (AT), and quenching‐austempering‐deep cryogenic treatment‐tempering (ACT). To investigate the effects of retained austenite (RA) with different morphologies, stabilities, and volume fractions on the wear resistance of NB steel, the microstructure is observed by optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The volume fraction and stability of RA are determined by quantitative X‐ray diffraction (XRD) analysis. It is found that deep cryogenic treatment (DCT) after low‐temperature austempering can effectively eliminate the blocky RA, increase the stability of filmy RA and have no effect on the NB microstructure. The AT and ACT treatments have higher surface residual compressive stress and better wear resistance than conventional QT treatments. For the ACT treatment, a multiphase microstructure composed of NB, martensite, and filmy RA is obtained near the surface, and the wear resistance of the steel is optimized, with increases of 23%, 52%, and 93% for austempering times of 8, 12, and 24 h, respectively. The results show that DCT can be combined with low‐temperature austempering treatment, thereby effectively eliminating unstable blocky RA, avoiding the transformation of brittle martensite, and obtaining improved wear resistance.

中文翻译：

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深冷处理对新型纳米贝氏体钢组织和耐磨性的影响

新型纳米贝氏体（NB）钢通过三种不同的热处理途径进行处理：淬火回火（QT），淬火回火回火（AT）和淬火回火深低温处理回火（ACT）。为了研究具有不同形态，稳定性和体积分数的残余奥氏体（RA）对NB钢的耐磨性的影响，通过光学显微镜（OM），扫描电子显微镜（SEM）和透射电子显微镜（ TEM）。RA的体积分数和稳定性通过定量X射线衍射（XRD）分析确定。发现低温奥氏体化后的深低温处理（DCT）可以有效消除块状RA，增加膜状RA的稳定性，并且对NB的微观结构没有影响。与常规QT处理相比，AT和ACT处理具有更高的表面残余压应力和更好的耐磨性。对于ACT处理，在表面附近获得了由NB，马氏体和薄膜状RA组成的多相显微组织，并且优化了钢的耐磨性，奥氏体回火时间8时，钢的耐磨性分别提高了23％，52％和93％。 ，分别为12、24小时。结果表明，DCT可以与低温奥氏体处理相结合，从而有效地消除不稳定的块状RA，避免了脆性马氏体的转变，并提高了耐磨性。并且优化了钢的耐磨性，奥氏体回火时间分别为8、12和24小时，分别增加了23％，52％和93％。结果表明，DCT可以与低温奥氏体处理相结合，从而有效地消除不稳定的块状RA，避免了脆性马氏体的转变，并提高了耐磨性。并且优化了钢的耐磨性，奥氏体回火时间分别为8、12和24小时，分别增加了23％，52％和93％。结果表明，DCT可以与低温奥氏体处理相结合，从而有效地消除不稳定的块状RA，避免了脆性马氏体的转变，并提高了耐磨性。