Work hardening in erosion due to single-particle impacts

Abstract

Successive work hardening and erosion of material were studied using single-particle impacts. A linear gas gun was used to impact steel balls of 3 mm diameter repeatedly at exactly the same location on 70-30 brass targets. An impact velocity of 120 m s −1 was used and the balls were impacted at angles of 25° and 90° to the target surface. Mass loss measurements on targets, initially cold worked to varying degrees, exhibited three stages of erosion, i.e. the incubation, the transition and the steady states. With increasing initial cold work, a higher rate of erosion was observed for both the normal and the oblique impact conditions. Photoplastic analysis and isohardness profile studies indicated the development of successively work-hardened substrate layers arising from repeated impacts. The analysis of substrate deformation led to the conclusion that erosion occurred only after the impacted surface was strained beyond the true tensile fracture strain of the material.