Microstructural stability of AISI 316L stainless steel processed by selective laser melting using different scanning strategies

Abstract

This project aims to evaluate the microstructural stability of AISI 316L austenitic stainless-steel samples processed by selective laser melting (SLM) by choosing four different scanning strategies. In most cases, the printed parts need to be heat treated after processing due to the high residual stresses developed upon processing. The materials processed by this additive manufacturing technique have unique microstructures that vary according to the processing conditions, in particular their texture and dislocation density. The samples were processed via SLM and are already available for this study. The materials will be characterized in the as-built condition and after isothermal annealing at 1150oC for several annealing times with emphasis on texture evolution upon static recrystallization. The microstructural characterization will be carried out by means of residual stress measurements in the "as-processed" condition using X-ray diffraction, Vickers microhardness testing and light optical and scanning electron microscopy. The corresponding dislocations densities will be evaluated by using two distinct approaches: quantitative metallography from electron channeling contrast images (ECCI) and X-ray diffraction using the modified Williamson-Hall method (peak broadening). Microtexture and evolution of recrystallized volume fraction will be evaluated by electron backscatter diffraction (EBSD) technique. (AU)