Comparative investigation of micromechanisms of plastic deformation by in-situ tensile tests of highly textured 316L steel

Sammanfattning: Additive manufacturing (AM) is identified as one of the best techniques in manufacturing components addressing most of the current challenges including material scarcity, design complexity, material compatibility, etc. Stainless steel 316L is one of the promising material candidates in AM due to its extraordinary properties that are useful in a wide variety of industries. Tailoring desired properties locally is heavily investigated in metal AM. This project focuses on investigating the plastic behavior of additively manufactured SS 316L parts printed using laser powder bed fusion (LPBF) specifically to have a strong crystal orientation towards the direction of loading. Parts were printed to have (100), (110), and fiber texture perpendicular to the tensile axis by changing the laser scanning direction. In-situ tensile tests were carried out in a Scanning Electron Microscope (SEM) acquiring electron backscatter diffraction (EBSD) data from the specimen at several strain levels. Schmid Factor (SF) maps, Kernel Average Misorientation (KAM) maps, and Grain orientation spread (GOS) maps were generated using EBSD data. Micromechanisms in plastic deformation of these highly textured AM parts were analyzed based on the crystal orientation and the microstructure. When the influence of crystallographic texture on the micromechanisms of plastic deformation was observed, it was confirmed that a significant difference is present in tensile properties directed with the crystal orientation. During plastic deformation, the crystals were heavily rotated to accommodate slip formations. The slips that are generated at the grains with fiber texture are restricted by the grain boundaries and therefore, showed a higher yield strength. The (100) texture was less prone to plastic deformation. The grains with (110) crystal orientation proved a higher ductility with a perfect slip starting at the grains with higher SFs and showed {111} <110> slip systems.