Molecular Dynamics Simulation of Microscopic Crack Initiation and Extension Mechanism in 8Cr4Mo4V Bearing Steels

To investigate the influences of cementite on the mechanics properties of the matrix and the initiation and propagation of microcracks in 8Cr4Mo4V bearing steels, molecular dynamics models were used to systematically analyze the effects of cementites geometric parameters(such as shape, size, and position)on crack initiation and extension mechanism. And combined with cohesive force theory, the characteristics of interface crack propagation were studied. The results indicate that cementite significantly enhances the mechanics properties of the bcc-Fe matrix, with smaller cementite particles providing a more pronounced strengthening effectiveness. While the shape and position of cementite exert a relatively minor impact on overall mechanics performance, sharper inclusions accelerate crack propagation, and the position of inclusions determines the crack propagation path. Furthermore, interfaces between the bcc-Fe matrix and cementite, as well as twin boundaries with larger misorientation angles, exhibit increased resistance to crack initiation and propagation.