Micro-Capillary Electrochemical and Microscopic Investigations of Massive and Individual Micrometer-Sized Powder Particles of Stainless Steel 316L

Material properties, corrosion, and metal release from stainless steel powders are important factors to assess any occupational health hazards. This paper elucidates the corrosion behavior of stainless steel particles (inert-gas-atomized AISI 316L powders sized < 45µm, polished and non-polished) compared with corresponding massive low-sulfur bulk sheet material. Electrochemical measurements using a microcapillary technique are compared with ex-situ optical and scanning electron microscopy imaging and electron dispersive X-ray spectroscopy elemental analysis on the same area of individual particles. Non-polished 316L particles were significantly more passive compared to polished massive sheet and polished particles that in general showed a similar corrosion behavior. Corrosion was not induced by bulk compositional differences but could be attributed to surface inhomogeneities. The results are in agreement with the high passivity of non-polished particles in macroscopic studies, an effect caused by an unique surface oxide, characterized in part I of this paper series