The formation and evolution of third body covered on 690 alloy tube during fretting in 285 ℃ air

The fretting wear tests of 690 alloy tube/405 stainless steel plate under various fretting cycles have been conducted in 285 ℃ air using a self-designed elevated-temperature fretting wear rig. The results demonstrated that the formation of third body layer (TBL) had considerable influence on the fretting wear performances of 690 alloy tube. The presence of TBL between the interfaces protected the partial 690 alloy tube surface from being damaged. Consequently, it resulted in the discontinuity of wear scar and reduction of coefficient of friction (COF) after approximately 500th cycles. Along the thickness of TBL, the contents of oxygen, chromium and iron took on obvious stratification induced by alternating the transfer layer and oxidation layer.