Interactive damage behaviors between rail corrosion and rolling contact in the marine atmospheric environment

Rails are subjected to severe corrosion challenges in marine atmospheres. In this study, U75V rail marine atmospheric corrosion behavior and dynamic coupling effects of corrosion on wear and rolling contact fatigue (RCF) were investigated using a marine atmospheric simulation system (NaCl deposition) and a twin-disc rolling contact simulation testing machine. The results indicated that rail marine atmospheric corrosion damage exhibited a typical pitting-dominated characteristic. As exposure time increased, initial discrete pitting coalesced laterally to form continuous corrosion patches, and the corrosion-induced thickness loss followed an exponential growth pattern (exponent n + 1 =1.97＞1). Moreover, as the NaCl deposition rate increased, rail corrosion became more severe, and the corrosion-induced thickness loss rapidly increased at first and then slowly, also following an exponential pattern (exponent C=0.5＜1). Under rail corrosion and wheel-rail rolling contact alternating conditions, compared to independent corrosion and rolling contact, the increment of rail mass loss accounted for 31 %-42 % of the total wear in the running-in test and 18 %-27 % in the alternating test. This increment was due to the increased local stress concentration and decreased work-hardening capacity caused by the uneven pitting and softened surface material under marine atmospheric corrosion. Also, due to the plastic flow during rolling contact, the micro-cracks embedded with corrosion products were initiated at the bottom of corrosion pitting, and continuous pitting led to surface cracks and material spalling. In addition, the rough rail surface and cracks caused by rolling contact further accelerated both the rate and uniformity of corrosion.