Evaluation of the plasticity index as a scuffing criterion

The plasticity index has often been invoked as an indicator of the most likely condition for scuffing of metals. The particular condition for initiating scuffing was thought to be 2% plastic strain in contacting asperities, which would lead to adhesion between asperities. E~eriments were done to validate the hypothesis using low alloy steels and stainless steel, lubricated with plain mineral oil and mineral oil containing 1% stearic acid, in slow single-pass sliding and in repeat pass sliding. Some experiments showed an influence of asperity slope on scuffing load as suggested by the plasticity index. Most experiments showed no such influence. All experiments showed that a great amount of plastic flow occurred before scuffing occurred.