Comparison of growth stresses developed in a thermally growing oxide on a nanocrystallised stainless steel, evaluated by in-situ Raman spectroscopy and numerical simulations
The 30th International Conference on Surface Modification Technologies (SMT30), Milan (Italy), 29 June - 1st July
Surface Mechanical Attrition Treatment (SMAT) is a recent process that enables to nanocrystallise the surface of metallic alloys. It can thus enhance mechanical properties of the treated material by inducing a grain refinement down to the nanometre scale, in the top surface layer. This nanocrystallisation process leads to different effects that were successively studied on different metallic materials. In the present work, investigations are performed on the influence of SMAT on high temperature oxidation resistance of a stainless steel. When metals or alloys are oxidized at high temperature, an oxide film generally develops. The existence of stress accompanying the oxide growth has been known for many years. In particular, the role of stresses during the isothermal oxidation process may influence the structure and the protective properties of the oxide scales. In the present work, those stresses are studied using in-situ Raman spectroscopy by measuring the mechanical kinetics with oxidation time. The results are then used to identify mechanochemical parameters and then compared to numerical simulations based on physical framework. The influence of the different studied SMAT conditions is then discussed.