Solidification crack characteristics and sensitivity of peritectic steel

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.