Fretting Tribocorrosion Behaviors of Marine Mooring Chain Steel 22MnCrNiMo in Artificial Seawater

The fretting wear behaviors of mooring chain steel 22MnCrNiMo specimens were evaluated in pure water and artificial seawater using a pin-on-flat configuration with 500-μm amplitude at room temperature for 2 h. Open-circuit potential tests and potentiodynamic anodic polarization were used to measure the alloy’s corrosion behaviors. Worn specimen surfaces were observed using scanning electron microscopy and wear volume loss determined using laser-scanning confocal microscopy. Comparative analyses of friction coefficient, wear volume loss, and worn surface morphologies were conducted. The results showed that the friction coefficients of 22MnCrNiMo friction pairs were in general smaller in seawater compared with that in pure water. Comparing contact stresses, sliding velocities had greater influence on tribocorrosion behavior of friction pairs in a marine environment. Moreover, wear volume loss of this steel in seawater was lower than that in pure water, indicating that corrosion had inhibitory effects on wear. With the increase of wear degree, the corrosion degree also increased, indicating that wear occurrence promoted corrosion. This also demonstrated a transformation of positive to negative interactions between corrosion and wear in the fretting corrosion and wear processes of this steel. The wear mechanism of the mooring chain steel 22MnCrNiMo was typically abrasion wear in pure water, whereas it was corrosion fatigue in seawater.