Tribocorrosion behaviour of stainless steel under cathodic potential

摘要

Tribocorrosion studies are usually performed at open circuit potential or under anodic potentials in order to describe the total wear degradation of material. Such approach needs to define a reference concerning the mechanical degradation in absence of corrosion. Indeed, experiments in the cathodic domain can be performed. Several authors have pointed out that mechanical wear can evolve as a function of the applied cathodic potential. Most of them suggest a role of hydrogen embrittlement on the wear mechanism.To understand the effect of hydrogen in the mechanical wear, results from tribocorrosion and nano-indentation have been compared. Wear volumes and surface morphologies are compared to the surface hardness evolution measured by nano-indentation. Two stainless steels have been selected: (ⅰ) a ferritique with carbides distributed homogenously in volume and (ⅱ) a dual phase ferrite-martensite. Both have the same chemical composition in order to avoid an effect of nickel, carbon and chromium.rnResults show an interaction between the hydrogen absorption mechanisms resulting on the surface hardness evolution and wear increase for lower cathodic potential applied, whereas the hydrogen evoluion to the surface for higher cathodic potential turn the wear from a wet to a dry mechanism.