The characteristics and sensitivity of solidification cracks in peritectic steels were investigated using directional solidification technology. Interdendritic cracks were observed in both hypoperitectic steels (12Cr1MoV, 15CrMo) and hyperperitectic steel (20CrMo) during solidification at growth velocities of 15, 50, and 80 μm/s. At the dendritic boundaries, sulphide precipitates were found, promoting crack formation. Based on the statistical analysis of interdendritic cracks in peritectic steels, the area ratio (R_A) of interdendritic cracks in a directional solidification structure was proposed to evaluate the crack sensitivity of peritectic steels. Furthermore, the crack sensitivities of peritectic steels (12Cr1MoV, 15CrMo, and 20CrMo) were tested, evaluated, and compared with the surface crack rates of three types of steels produced from a steel plant. The results demonstrated that R_A was in good agreement with that of the steel plant, and the crack sensitivity of 12Cr1MoV steel was the strongest, followed by that of 15CrMo and 20CrMo steels. Thus, R_A can be used to evaluate the crack sensitivity of peritectic steel.

采用定向凝固技术研究了包晶钢凝固裂纹的特征和敏感性。在生长速度为 15、50 和 80 μm/s 的凝固过程中，亚包晶钢 (12Cr1MoV、15CrMo) 和过包晶钢 (20CrMo) 均观察到枝晶间裂纹。在枝晶边界处，发现了硫化物沉淀，促进了裂纹的形成。基于包晶钢枝晶间裂纹的统计分析，提出了定向凝固组织中枝晶间裂纹面积比（ R _{A ）来评价包晶钢的裂纹敏感性。}此外，还测试、评估了包晶钢（12Cr1MoV、15CrMo 和 20CrMo）的裂纹敏感性，并与钢厂生产的三种钢的表面裂纹率进行了比较。结果表明，R _A与钢厂的吻合较好，12Cr1MoV 钢的裂纹敏感性最强，其次是 15CrMo 和 20CrMo 钢。因此，R _A可用于评价包晶钢的裂纹敏感性。