In Situ Observation of Heat Generation Behaviour on Steel Surface During Scuffing Process

In the current study, the heat generation behaviour at plastic flow area in the contact area during a scuffing process was observed in situ using a monochrome high-speed camera that detected both visible and near-infrared light. The scuffing test was conducted using a pin-on-disc test rig comprising a rotating sapphire disc and a fixed martensitic steel pin. Engine oil was supplied as a lubricant. The images captured by the high-speed camera clearly showed changes in the contact area and the heat generation behaviour. It was found that the heat generation behaviour could be classified into three stages during scuffing. In the first stage, local heat generation occurred intermittently at local severe contact points, such as the passing of transfer layers on the sapphire disc and the trailing edge of the contact area. In the second stage, heat generation occurred intermittently over larger areas in which heat had been generated until that time. When the entire contact area had previously generated heat, heat generation became continuous throughout the contact area in the third stage. During the third stage, the contact area was increased rapidly, which caused catastrophic failure. These results highlight important questions regarding material phenomena that remain to be investigated.