The microstructure and mechanical properties of pearlite in 45Cr4NiMoV and 50Cr5NiMoV steels were studied and compared. The microstructural characteristics of pearlite of two steels were carefully examined by optical microscopy, scanning electron microscopy and transmission electron microscopy (TEM), and the type, size and relative amount of extracted carbide particles were analyzed by X-ray diffraction and TEM coupled with selected area electron diffraction. The hardness, tensile property, impact and fracture toughness of pearlite of two steels were also evaluated. Besides, the carbide dissolution kinetics of 45Cr4NiMoV and 50Cr5NiMoV steels were clarified. The results indicated that the carbides in 50Cr5NiMoV steel exhibited higher dissolution temperature than those in 45Cr4NiMoV steel, which induced different morphologies of pearlite after eutectoid transformation. Compared to the pearlite with lamellar M₂₃C₆ carbides in 45Cr4NiMoV steel, the pearlite with the mixture of spheroidized M₇C₃ and lamellar M₂₃C₆ carbides in 50Cr5NiMoV steel possessed higher impact and plane-strain fracture toughness but lower hardness and strength, because different pearlite morphologies led to different mechanical properties. In order to further improve the comprehensive properties of the steels, the fraction of M₇C₃ for the material with acceptable properties was examined and dissolution kinetic of M₇C₃ was calculated. Therefore, the austenitizing temperature and holding time could be appropriately selected to keep enough undissolved M₇C₃ in the steels.

对45Cr4NiMoV和50Cr5NiMoV钢中珠光体的显微组织和力学性能进行了研究和比较。采用光学显微镜、扫描电子显微镜和透射电子显微镜（TEM）对两种钢珠光体的显微组织特征进行了仔细研究，并通过X射线衍射和TEM耦合选择分析了提取的碳化物颗粒的类型、尺寸和相对量。面电子衍射。还评价了两种钢珠光体的硬度、拉伸性能、冲击和断裂韧性。此外，还阐明了 45Cr4NiMoV 和 50Cr5NiMoV 钢的碳化物溶解动力学。结果表明，50Cr5NiMoV钢中碳化物的溶解温度高于45Cr4NiMoV钢，导致共析转变后珠光体的不同形态。与层状M的珠光体相比_{45Cr4NiMoV钢中的23} C ₆碳化物，50Cr5NiMoV钢中球化M ₇ C ₃和层状M ₂₃ C ₆碳化物混合的珠光体具有较高的冲击和平面应变断裂韧性，但硬度和强度较低，因为不同的珠光体形貌导致不同的力学性能。为了进一步提高钢的综合性能，对性能合格材料的M 7 C 3 分数和M ₇ C _3的溶解_动力学进行了检测。进行了计算。因此，可以适当地选择奥斯丁化温度和保持时间，以将足够的未溶解的M ₇ C ₃保持在钢中。