The microstructure evolution and micro-mechanical behavior of secondary carbides at grain boundary in a Fe–Cr–W–Mo–V–C alloy for cold work roll were systematically investigated in this study. The typical microstructures at the characteristic temperature of 1240 °C, 1200 °C and 1150 °C were observed by Optical Microscope and Field Emission Scanning Electron Microscope. The hardness values of secondary carbides were predicted and measured by first-principles calculation, Vickers hardness tester and nanoindentation technique. The fracture toughness (K_C) values were calculated by a method known as Indentation Microfracture. Single-pass scratch tests were carried out to investigate the micro-scale wear behavior of secondary carbides. The macroscopic pin-on-disk test was also performed. The results show that the secondary carbide at grain boundary contains secondary MC, M₂C and M₇C₃. The formation of secondary MC and M₇C₃ belongs to the precipitation and growth process, while secondary M₂C is the result from the growth of eutectic M₂C. In the studied alloy, M₇C₃ is a dominant carbide in quantity, and has higher hardness than secondary M₂C and the matrix, and processes the better toughness than secondary MC, whose hardness almost reaches 30 GPa, and can also effectively resist the crack initiation and propagation, which therefore makes a significant contribution to the wear resistance of the alloy.

本研究系统地研究了冷作辊用Fe–Cr–W–Mo–V–C合金中晶界处次生碳化物的组织演变和微观力学行为。用光学显微镜和场发射扫描电子显微镜观察到特征温度为1240°C，1200°C和1150°C时的典型显微组织。通过第一性原理计算，维氏硬度计和纳米压痕技术预测和测量了二次碳化物的硬度值。断裂韧性（K _C）值是通过称为压痕微断裂的方法计算的。进行了单次通过刮擦测试，以研究次生碳化物的微观磨损行为。还进行了宏观的针在磁盘上的测试。结果表明，晶界的二次碳化物含有二次MC，M ₂ C和M ₇ C ₃。次生MC和M ₇ C _3的形成属于沉淀和生长过程，而次生M ₂ C是共晶M ₂ C的生长结果。在研究的合金中，M ₇ C ₃是数量上占主导地位的碳化物，并且具有比次级M ₂高的硬度C和基体的韧性要优于次要MC，后者的硬度几乎达到30 GPa，并且还可以有效地抵抗裂纹的产生和扩展，因此对合金的耐磨性做出了重要贡献。