Improvement of wear resistance for engine valve: introducing cold upsetting treatment on valve seating face

This study presents a new surface strengthening technique (cold upsetting manufacturing process) for engine valve seating face (VSF). The properties of the Ni30 superalloy VSF were characterized before and after cold upsetting. Compared to the solution-aging treatment (SAT) valve, the solution-cold upsetting-aging treatment (SCUAT) valve hardness was increased by 60 HV0.2. SCUAT valves exhibited higher internal dislocation degrees and local misorientation than SAT valves. Bench-top wear tests at 650 °C and 750 °C were conducted. The valve wear loss at 650 °C was higher than that at 750 °C. SCUAT valves show better wear resistance, with a total wear loss reduction up to 26.76 %. The SCUAT valve-seat insert contact pair wear mechanisms are adhesive and fatigue wear.