Cyclic cryogenic treatment, a major cycle accompanied by zero or more subsidiary cycles, was conducted on the hardened 42CrMo steel using orthogonal design method to investigate the effect of different parameters (cryogenic temperature, holding time, and cycles number) of cryogenic treatment on wear resistance and impact toughness of the steel. Range analysis was performed to obtain the influencing order of the three parameters and their optimum values. The results show that after cryogenic treatment, the steel exhibits higher wear resistance and impact toughness, whereas no significant change in hardness. For wear resistance, the influencing order of parameters is cryogenic temperature, holding time, and cycles number, and the optimum values of the parameters are −160°C, 24 h and two cycles, respectively. For impact toughness, the influencing order of parameters is cryogenic temperature, cycles number, and holding time, and the optimum values are −120°C, 24 h and three cycles, respectively. The wear topography and fracture topography were examined using scanning electronic microscopy (SEM) to investigate the wear mechanism and fracture mechanism of the steel after cryogenic treatment, respectively. The results show that after cryogenic treatment, the wear mechanism is the combination of abrasive wear and adhesive wear with oxidative wear, and the fracture mechanism is a quasicleavage fracture. The microstructure was also examined by SEM to investigate the influencing mechanism of cryogenic treatment for improving wear resistance and impact toughness of the steel. It suggests that more precipitation of fine carbides dispersively distributed in the matrix is responsible for the beneficial effect of cryogenic treatment on wear resistance and impact toughness of the steel.

中文翻译：

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循环低温处理对42CrMo钢耐磨性，冲击韧性和组织的影响及其优化

使用正交设计方法对淬硬的42CrMo钢进行了循环低温处理，该主循环伴随着零个或多个辅助循环，以研究低温处理的不同参数（低温温度，保持时间和循环次数）对耐磨性的影响和钢的冲击韧性。进行范围分析以获得三个参数的影响顺序及其最佳值。结果表明，低温处理后的钢具有较高的耐磨性和冲击韧性，而硬度没有明显变化。对于耐磨性，参数的影响顺序为低温温度，保持时间和循环次数，并且参数的最佳值分别为-160°C，24 h和两个循环。对于冲击韧性，参数的影响顺序为低温温度，循环次数和保持时间，最佳值为分别为-120°C，24 h和3个循环。使用扫描电子显微镜（SEM）检查磨损形貌和断裂形貌，以分别研究低温处理后钢的磨损机理和断裂机理。结果表明，低温处理后的磨损机理是磨料磨损和胶粘剂磨损与氧化磨损的结合，断裂机理是准断裂。还通过SEM检查了显微组织，以研究低温处理对改善钢的耐磨性和冲击韧性的影响机理。