The role of fracture toughness in the wear of metals

Abstract

A model is proposed to explain increasing relative wear rates with decreasing toughness of metallic materials. It is based on the comparison of the strain that occurs during asperity interactions with the critical strain at which crack growth is initiated. If the applied strain is smaller than the critical strain, the wear rate is independent of toughness and Archard's law is followed. Applied strain larger than the critical strain of the material lead to an increased probability of crack growth and therefore to a higher wear rate. The transition to an increased wear rate (Ranges I → II) depends on the conditions of the particular wear experiment, for example, pressure, strain rate, impingement angle, and on the properties of the material. In Range I the wear coefficient is constant at the minimum value, wear resistance increases proportional to hardness. Wear rate in Range II can increase (less than in Range I), be independent of, or decrease with hardness depending on the particular toughness