Deformation Mechanisms of 316L Austenitic Stainless Steel Tubes under Equal Channel Angular Pressing

This study investigates the deformation mechanisms of 316L austenitic stainless steel tubes processed by equal channel angular pressing (ECAP) at room temperature. Nanoindentation tests were used to study the influence of the 1-pass ECAP process on mechanical properties. The microstructure evolution of specimens subjected to 1-pass ECAP process was systematically analyzed using a variety of characterization methods. The results from microstructures observed through cross sections and longitudinal sections of deformed samples at different areas showed that the grains were refined significantly by the 1-pass ECAP process, and numerous deformation twins were generated. The microstructures also showed that the 1-pass ECAP process can cause uneven refinement of grains due to inhomogeneous strain distribution. Significant changes in grain orientation and micro-texture were found during the 1-pass ECAP process. The deformation mechanisms of samples subjected to the 1-pass ECAP process consisted of two stages: dislocation slip and twinning. The observed plastic deformation by dislocation slip occurred prior to activate twinning, and severe plastic deformation mainly occurred near grain boundaries or twin boundaries.