Selective oxidation of martensitic stainless steelThursday (29.09.2016) 12:00 - 12:15 Part of:
Modern consumer products need high precision metallic parts to meet the quality demands of consumers. Therefore surfaces of commercial products not only need to be resistant to corrosion, but also have an appealing surface finish. Commonly used sequential processing steps with martensitic chromium steel are to apply metal forming to achieve the desired shape and then apply a heat treatment to attain the required mechanical strength. This hardening process includes phase transformations in the bulk. Consequently the protective passive layer is subjective to changes during the fabrication process, i.e. the thickness of the iron- and chromium oxide rich layer increases. Recovery of this outer layer is crucial for protection of the bulk against corrosion during service. Observations of the stainless steel surface after hardening and tempering indicate that individual grains are more susceptible for oxidation than others. We have examined the dynamics of the grains and carbides during the heat treatment with high temperature EBSD. This study is aimed at identifying the possible relation between grain orientation, local composition of the passive layer and corrosion resistance.