Metallurgical appraisal of wear mechanisms and processes on high-speed-steel cutting tools

Abstract

The wear mechanisms and processes on high-speed-steel tools used to machine steels, cast iron and a nickel-based alloy under conditions encountered in practice have been investigated. Evidence is presented of five different wear processes: (a) superficial plastic deformation by shear at high temperature; (b) plastic deformation of the cutting edge; (c) wear based on diffusion; (d) attrition wear; (e) abrasion wear. All these wear processes operate under conditions of seizure between tool and work material, and frequently more than one process is taking place at the same time. The first three are dependent on temperature, and temperature distribution in the tool is of major importance. Cratering can be caused by (a) or by (c), the former being rapid and the latter relatively slow. Flank wear may be caused by diffusion (c) or by attrition (d). Evidence of abrasion (e) by Ti(C,N) particles in stabilized austenitic stainless steel is conclusive. In the range of materials tested, however, the contribution of abrasion to tool wear appeared to be small. The pattern of flow of the work material around the tool edge plays a decisive role in determining which wear processes become operative and the rate of wear.