Effect of multiple ultrasonic nanocrystal surface modification on surface integrity and wear property of DZ2 axle steel

Abstract

Abstract Ultrasonic nanocrystal surface modification (UNSM) treatments with different numbers of rolling passes are employed to enhance the surface integrity and the wear resistance of DZ2 axle steel for high-speed trains. In this study, microstructures, residual stress, and wear properties of the DZ2 axle steel after multiple UNSM treatments were investigated. The results showed grain refinements in the near-surface layer of the DZ2 axle steel after multiple UNSM treatments. Compared with the untreated sample, the compressive residual stress of the surface increased from -73 to -703 MPa, and the surface microhardness increased from 220 to 283 HV0.2. The results from wear tests showed that the sample with UNSM treatment of three rolling passes exhibited a significantly enhanced wear resistance under sliding conditions.