Investigation of the fretting corrosion mechanism of QPQ-treated TP316H steel in liquid sodium at 450 °C.

The fretting corrosion behavior of quench–polish–quench (QPQ)-treated TP316H steel was investigated in liquid sodium at 450 °C. The surface of the sample after QPQ is a multi-layer structure, consisting of the outermost oxide layer, the middle nitriding layer, and an underneath diffusion layer. The fretting wear and corrosion increased the material damage. With increasing thickness of the nitriding layer, the cross-sectional hardness and wear resistance remarkably increased, the fretting corrosion volume decreased. The effect of multilayer structure anti-wear and anti-corrosion were examined. Possible fretting corrosion mechanisms of the multilayer structure prepared by QPQ on TP316H in liquid sodium are discussed. • Time of QPQ treatments influence the multilayer structure of modified surface. • The high-hardness nitriding layer exerts the main anti-wear effect. • The diffusion layer exerts better anti-corrosion effect, and decomposes into the harder CrN and α-Fe phases. • QPQ treatments are promising for combating fretting corrosion of TP316H in liquid sodium. [ABSTRACT FROM AUTHOR]