An elasto-plastic self-consistent model with hardening based on dislocation density, twinning and de-twinning: Application to strain path changes in HCP metals

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:638

Article

Zecevic, Milovan¹  Knezevic, Marko¹  Beyerlein, Irene J.²  Tome, Carlos N.³ 

[1] Univ New Hampshire, Dept Mech Engn, Durham, NH 03824 USA

[2] Los Alamos Natl Lab, Div Theoret, Los Alamos, NM 87545 USA

[3] Los Alamos Natl Lab, Mat Sci & Technol Div, Los Alamos, NM 87545 USA

关键词: Hexagonal metals;    Polycrystals;    Dislocations;    Twinning;    De-twinning;    Texture;   

DOI  :  10.1016/j.msea.2015.04.066

来源: Elsevier

【 摘 要 】

In this work, we develop a polycrystal mean-field constitutive model based on an elastic-plastic self-consistent (EPSC) framework. In this model, we incorporate recently developed subgrain models for dislocation density evolution with thermally activated slip, twin activation via statistical stress fluctuations, reoriented twin domains within the grain and associated stress relaxation, twin boundary hardening, and de-twinning. The model is applied to a systematic set of strain path change tests on pure beryllium (Be). Under the applied deformation conditions, Be deforms by multiple slip modes and deformation twinning and thereby provides a challenging test for model validation. With a single set of material parameters, determined using the flow-stress vs. strain responses during monotonic testing, the model predicts well the evolution of texture, lattice strains, and twinning. With further analysis, we demonstrate the significant influence of internal residual stresses on (1) the flow stress drop when reloading from one path to another, (2) deformation twin activation, (3) de-twinning during a reversal strain path change, and (4) the formation of additional twin variants during a cross-loading sequence. The model presented here can, in principle, be applied to other metals, deforming by multiple slip and twinning modes under a wide range of temperature, strain rate, and strain path conditions. (C) 2015 Elsevier B.V. All rights reserved.

【 授权许可】

Free