Microstructural Behavior of 316L Austenitic Stainless Steel Under Groove Pressing (GP)

The microstructural behavior of 316L austenitic stainless steel sheets subjected to severe plastic deformation (SPD) by the constrained groove pressing (CGP) technique without mass flow limitation up to 4 passes was analyzed. Two tool steel dies were used: a corrugated die with geometry (t = 2 mm and angle of 45°) and a flat die generating a maximum equivalent deformation of ε~4.64. The microstructural behavior was analyzed using characterization techniques: Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Electron Backscatter Diffraction (EBSD). The results were analyzed from three different perspectives: 1. SEM was used to evaluate the presence of martensite induced by deformation. 2. The presence of martensite of the ε and α' types were confirmed by XRD, and 3. The effect of severe plastic deformation on the behavior of the austenitic grain in a steel with an SFE=28 mJ/m2 was analyzed by EBSD. The results showed a significant reduction in the austenitic grain size in the presence of special Ʃ3-type boundaries. Regarding the deformation mechanisms, the presence of dislocation gliding and mechanical twinning was observed, with the transformation of austenite → twinning austenite → martensite (α').