Effect of Intermetallic and Secondary Phases on Dry and Wet Sliding Wear Behavior of Super Duplex Stainless Steel

The purpose of this investigation was to quantify the effects of intermetallic and secondary phases on the sliding wear behavior of super duplex stainless steel 2507 against bearing steel type EN-31 under both dry and wet contact conditions. Phases were precipitated by suitable heat treatment in the range of 475–875 °C. A pin-on-disc technique was used to investigate the wear characteristics in the wet environment of 3.5% NaCl solution, 1 M HCl solution, 10−2 M sodium thiosulfate solution, and artificial ocean water. These media were chosen to closely match the actual service environment of super duplex stainless steel 2507. Pins were slid against a disc of EN-31 steel for distances of 1,000, 1,500, 2,000, 2,500, and 3,000 m. Results indicate that precipitation of the sigma phase gives the best wear resistivity, followed by precipitation of chi and R phases and then precipitation of the α′ phase. The experimental investigations reveal that hydrogen in acidic medium accelerates the reaction kinetic compared to the neutral medium because of the different cathodic reactions. Progressive wear was closely observed using the change in the sliding pin’s contact face profile and corresponding weight loss data. Scanning electron microscopy was used to study the wear mechanism.