[en] Stress corrosion cracking (SCC) and oxidation tests were performed on 316L stainless steel manufactured by wire laser additive manufacturing (WLAM) in hydrogenated Pressurized Water Reactors (PWR) environment. The influence of stress-relief and solution annealed heat treatments on microstructure and mechanical properties was assessed and compared to conventionally manufactured 316L. Oxidation tests revealed similar corrosion behavior between WLAM and conventional solution-annealed Stainless Steels (SS). The cracks network after SSRT tests was estimated by SEM observations. Intergranular stress corrosion cracking (IGSCC) was detected in solution-annealed (SA) samples while only transgranular cracks were identified in stress-relieved (SR) ones. Results show that a high temperature heat treatment significantly affected the SCC susceptibility of WLAM samples. It is believed that the high-density delta ferrite, which was only observed in the SR samples, may affect the cracking mode, and lead to the formation of short transgranular cracks. (author)

[en] Laser powder bed fusion, largely employed for additive manufacturing, induces after each batch a large quantity of remaining powder. This study focuses on the possibility to reuse this remaining powder after a large number of production cycles and on the influence of such reusing on the microstructure and mechanical properties. Inconel 718 parts made from fresh and 50 times reused powder were processed and then characterized in the as-built state. The effect of powder reuse on the microstructure was assessed thanks to a multiscale study and the resulting mechanical response was evaluated using both monotonous and cyclic tests. Our results clearly show that despite a better powder flowability for the reused powder, only minor differences between the two investigated materials demonstrating the possibility of high-quality parts production from reused powders.