X-ray study of relation between impurity induced embrittlement and residual strains in intergranular fracture surfaces

Measurements of X-ray line broadening and line shifts were made on intergranular fracture surfaces of a Ni-Cr steel doped with phosphorus. Excess line broadening and line shifts were found to be associated with a layer 1–2 μm thick along the fracture surfaces, and the amounts decreased as the intergranular phosphorus concentration increased. These phenomena are interpreted as being the result of local plastic deformation during brittle crack propagation. The fact that the phenomena decrease with increasing embrittlement is consistent with recent ideas on the relation between the plastic work of fracture and the intergranular cohesive strength, particularly as it is affected by impurity segregation.