FEM Study of Driving Forces of Short Cracks at Inclusions in Hard Steels

摘要

A finite element model was formulated for an equatorial crack growing from aspherical inclusion into the surrounding steel matrix. The elastic inclusion and the elasto-plastic matrix were given material parameters corresponding to alumina inclusions in martensitic bearing steels. The effects of different thermal contraction in the inclusion and matrix during cooling after heat treatment was considered. A number of different events in the crack growth process were studied like decohesion of the matrix from the inclusion, frictional contact between the matrix and the inclusion and cracking of the inclusion itself. Different inclusion configurations were compared to the situation for a crack growing from a spherical pore. The latter case simulates a sulfide inclusion.