Effect of rainfall pH value on fretting corrosion characteristics of 60Si2Mn steel for high-speed railway track fastener clips

Fretting corrosion degrades the materials of high-speed railway track fastener clips. It reduces their mechanical properties, affecting the service performance of the fastener and even threatens the safety of train operations. To explore the fretting corrosion characteristics of high-speed railway clips, the spatial coupling distribution diagram of the annual mean pH value of rainfall in China's high-speed railway network is proposed, the pH value parameter range of the fretting corrosion test was then determined. Fretting corrosion tests were carried out on 60Si2Mn steel of high-speed railway fastener clips. The fretting behavior and damage mechanism of the clips' materials under different rainfall pH values are discussed in detail. Faraday's law is then used to study the interaction between the wear and corrosion of the clips. The results show that there are different wear mechanisms at different pH values. The wear mechanisms in acidic conditions with a pH value of 4.5 and above are mainly abrasive and corrosive wear, accompanied by fatigue wear. In conditions with a pH value of 7.0, the wear mechanisms are mainly abrasive wear and oxidative wear. For alkaline conditions where the pH is 8.5 and below, these mechanisms are mainly abrasive and oxidative wear. The acidic and alkaline environments will strengthen the abrasive wear effect. The corrosive environment will strengthen the abrasive wear effect and increase the wear amount on the contact surface of the clips. The corresponding wear amount is the largest at a pH value of 4.5, followed by 5.5, 8.5, and the smallest at 7.0. Compared with the pH value of 7.0, wear and corrosion will promote each other under acidic and alkaline conditions, presenting a "positive interaction."