Additively manufactured 316L stainless steel via laser powder directed energy deposition (LP-DED): Mechanical properties at cryogenic and elevated temperatures

316L austenitic stainless steel (SS) has excellent corrosion resistance with decent cryogenic and intermediate temperature mechanical properties and compatibility with additive manufacturing (AM) processes. While mechanical behavior of wrought 316L SS at different temperatures has been well reported, that for AM 316L SS is still not well understood. This study characterizes the microstructure and temperature dependent mechanical behavior, including both tensile and fatigue, of 316L SS manufactured via laser powder directed energy deposition (LP-DED). The specimens undergo post-manufacture treatment of stress relieving (899 °C/2h), hot isostatic pressing (1163 °C/3h under 103 MPa), and solution annealing (1100 °C/2h) followed by surface machining. The tensile strengths reduce with increasing testing temperature. A concomitant change in tensile deformation mechanism is observed from martensitic transformation at −196 °C, to deformation twinning at 21 °C, to dislocation slip at 204 °C, 427 °C, and 649 °C, and to dynamic recrystallization at 871 °C and 982 °C. Crystallographic facets forming 45° angles with the loading axis are observed in the crack initiating regions only at lower temperatures (21 °C, 204 °C, and 427 °C). The generated tensile data are compared against the wrought and laser powder bed fused (L-PBF) counterparts, and the fatigue data are compared with the wrought ones form literature.