Patterns of Fracture Initiation in Metallic Materials with a Heterogeneous Structure under Dynamic Cyclic Loading

Abstract

The process of nucleation of fatigue defects in metal alloys with different structural morphology is considered. A physical model was built, calculation expressions were presented, a numerical experiment was performed to determine the moment of nucleation of the critical-size defect in Fe-based alloys during high-speed droplet impacts. The physical model is based on the theory of dislocations. It is shown that the determining factor in the process of wear nucleation under dynamic cyclic loading has a structural factor. Depending on the structure and properties of the material, as well as on the nature of the loads, the critical fatigue defect develops in the form of cracks, pores or microcraters. Comparative data of calculations and bench tests for droplet impingement erosion were presented. The contribution of the nucleation stage during the incubation period of erosive wear of the materials studied was evaluated. Due to the fact that rigorous instrumental methods for determining the duration of the nucleation stage are absent, the usage of the proposed analytical model is recommended for this purpose.