| The interaction phenomena between dislocations and a grain boundary have been examined by conducting in-situ straining experiments with 316 stainless steel in a TEM. An emphasis was put on especially for the identification of the critical factors affecting slip transfer across a grain boundary. Various types of dislocation interactions with grain boundary were observed during in-situ deformation experiments, such as dislocation absorption into grain boundary, reflection from grain boundary, transmission across grain boundary, and microcrack initiation at grain boundary. Each phenomenon is considered as an effective relaxation mechanism for the accumulated internal strain energy induced by piled-up dislocations against grain boundary. The slip transfer across grain boundray was found to be affected by the geometric relationship between the two adjacent grains and also by the internal stress generated by a dislocation pile-up. The activated slip system could, therefore, be predicted by such factors as 1) the minimum intersection angle between the two slip planes in the two adjacent grains, 2) the largest resolved shear stress acting on the neighboring grain under the stress field caused by a dislocation pile-up, and 3) the smallest Burgers vector of residual dislocations remaining in the grain boundary after a slip transfer. These results appear to be in good agreement with the present direct observations of slip transfer behavior. |
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