Investigation on the interaction between corrosion and wear of U68CuCr rail steel with different corrosion periods

The interaction between corrosion and wear of U68CuCr rail steel was investigated. The samples were alternately subjected to the neutral salt spray tests with different corrosion periods (6, 24 and 48 h) and rolling friction wear test for 4 h. The corrosion and wear rates after the corrosion test and wear test were measured, respectively. The surface morphologies of the rail samples after the corrosion test and wear test, and the subsurface morphologies of the rail samples after the last test were observed. The results show that compared to the samples without corrosion, the damage degree of the corroded samples after wear tests became severer, and the wear mass loss and wear rate increased with the number of corrosion-wear cycle. In addition, rolling contact fatigue cracks initiated and propagated at a high angle and the structure of sample surface became unstable after corrosion, leading to easy spalling during the following wear tests compared to the only wear tests without corrosion. Moreover, the plastic deformation layer was destroyed by corrosion and the area of wear pits increased after the interaction test. Therefore, wear was accelerated by corrosion, and the longer is the corrosion period, the more severe is the wear degree. Additionally, regarding to the effect of wear on corrosion, corrosion was accelerated by wear. This is attributed to the facts that (1) the wear pits and delamination on the worn samples provided favorable locations for the deposition of the salt spray solution during the corrosion, and (2) the subsurface and matrix were corroded along rolling contact fatigue cracks to increase the corrosion rate during the corrosion test after wear. This work provides a foundation to the further investigation on the interaction between corrosion and wear of steels.