Failure Analysis of X38 Die Steel for Hot Forging

The early fracture of X38 hot forging die occurred. The failure causes of X38 die steel for hot forging were comprehensively analyzed by means of metallographic analysis, hardness test, and fracture observation. The results show that a large number of MnS inclusions are found in the crack fracture, some secondary phases are precipitated at the grain boundary, and the carbides are not completely dissolved into the matrix. The failure fracture of the die is quasi-cleavage fracture with small plastic deformation. It shows that the austenitizing of the material is not complete, and the tempering temperature is too high. The crack initiation is caused by the stress concentration caused by more inclusions and the poor strength and toughness of the material caused by the poor heat treatment system, which accelerates the crack propagation speed.