Quantitative evaluations for strain amplitude dependent organization of dislocation structures due to cyclic plasticity in austenitic stainless steel 316L

This study is a quantitative evaluation of dislocation structures due to cyclic plasticity with small strain amplitudes in austenitic stainless steel 316L. First, dislocation structures in specimens after 100 cycles of cyclic loading with strain amplitudes of 0.251%, 0.75% and 1.0% were observed by transmission electron microscopy (TEM). The observations showed that cyclic loading with larger strain amplitudes results in the organization of more uniform dislocation cell structures. Secondly, an image analysis method for evaluation of the TEM images is proposed. The proposed method quantitatively evaluates the strain amplitude dependency of the organization of dislocation structures. Finally, the accumulation of shear slips on slip systems during cyclic loading is estimated by using crystal plasticity finite element analysis. The distribution of the accumulated shear slips correlates with the organization of dislocation structures. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.