Evolution of wear damage in Inconel 600 alloy due to fretting against type 304 stainless steel

Fretting wear damage is a concern in heat exchanger tube of Inconel 600 in nuclear power plants. Fretting wear tests of Inconel 600 alloy against stainless steel type 304 were performed for the purpose to identify changes in the wear mechanisms with number of cycles. The results indicated that as cycles increased, the wear volume, worn scar depth and plastic regime at the scar edge first slowly increased, and then showed a significant increase. Correspondingly, the wear mechanism transformed from local adhesive damage to a combination of oxidation and delamination wear. A tribologically transformed structure (TTS) layer formed after a minimum number of cycles had been reached. Fatigue cracks nucleated in the stick-slip zone, and propagated along a direction of 40-50° to the worn surface, then into TTS layer after it was formed. With further increases of cycle number, fatigue cracks destroyed the TTS layer, and that eventually led to a transition in the wear mechanism.