Effect of normal force on fretting wear behavior and mechanism of Alloy 690TT in high temperature water

Fretting wear experiments have been performed in high temperature water with a range of normal forces to investigate the wear behavior of Alloy 690TT tube sections oscillating against stainless steel Type 304 plates. Alloy 690TT is a Ni-based alloy containing Fe, Cr, and other minor additions. Results of tests conducted in an autoclave chamber in pressurized 288 °C water, indicated that fretting wear processes mainly consisted of adhesive wear, abrasive wear, delamination, material transfer, and oxidation. As normal force increased, the initial contact area also increased, resulting in the increase of wear area as well as wear depth. Fretting wear promoted the oxidation of fresh material, and the mechanism corresponded in certain aspects to static oxidation. That is, the outermost surface layer consisted of an Fe-rich spinel, while Cr2O3 existed in the inner layer after fresh materials were exposed to the testing environment.