Erosion effect of atomic oxygen on the 321 stainless steel

The 321 stainless steel was tested subjected to atomic oxygen (AO) exposure to investigate the effect of AO in LEO environment. The mass loss, miro-roughness, and surface hardness were measured. The chemical composition and microstructure in the exposed surface layer were analyzed using XPS and TEM technique. The results show that the AO has an erosion effect on the stainless steel in the range of thin surface layer, leading to increase of micro-roughness. The long term exposure to AO results in an increase in oxygen content of the surface layer, forming metallic oxide. At the same time, the martensite phase which does not exist in the 321 stainless steel before AO exposure was detected after AO exposure, resulting in distinct surface hardening. The oxidative stress should be one of the major reasons for the surface eroding and hardening induced by AO exposure.