Ratcheting Strain and Microstructure Evolution of AZ31B Magnesium Alloy under a Tensile-Tensile Cyclic Loading

Zhifeng Yan; Denghui Wang; Wenxian Wang; Jun Zhou; Xiuli He; Peng Dong; Hongxia Zhang; Liyong Sun

doi:10.3390/ma11040513

Ratcheting Strain and Microstructure Evolution of AZ31B Magnesium Alloy under a Tensile-Tensile Cyclic Loading

Materials (Basel). 2018 Mar 28;11(4):513. doi: 10.3390/ma11040513.

Authors

Zhifeng Yan¹, Denghui Wang², Wenxian Wang³, Jun Zhou^{4

5}, Xiuli He^{6

7}, Peng Dong⁸, Hongxia Zhang⁹, Liyong Sun¹⁰

Affiliations

¹ Shanxi Key Laboratory of Advanced Magnesium-Based Materials, School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China. yanzhifeng@tyut.edu.cn.
² Shanxi Key Laboratory of Advanced Magnesium-Based Materials, School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China. 18503437855@163.com.
³ Shanxi Key Laboratory of Advanced Magnesium-Based Materials, School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China. wwx960@126.com.
⁴ Shanxi Key Laboratory of Advanced Magnesium-Based Materials, School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China. juz17@psu.edu.
⁵ School of Engineering, The Behrend College, Pennsylvania State University Erie, Erie, PA 16563, USA. juz17@psu.edu.
⁶ Shanxi Key Laboratory of Advanced Magnesium-Based Materials, School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China. hexl_ocean@163.com.
⁷ Department of Mechanical Engineering, Taiyuan Institute of Technology, No. 31, Xinlan Road, Taiyuan 030008, China. hexl_ocean@163.com.
⁸ Shanxi Key Laboratory of Advanced Magnesium-Based Materials, School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China. dongpeng@tyut.edu.cn.
⁹ Shanxi Key Laboratory of Advanced Magnesium-Based Materials, School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China. hongxzhang@163.com.
¹⁰ School of Engineering, The Behrend College, Pennsylvania State University Erie, Erie, PA 16563, USA. lus28@psu.edu.

Abstract

In this paper, studies were conducted to investigate the deformation behavior and microstructure change in a hot-rolled AZ31B magnesium alloy during a tensile-tensile cyclic loading. The relationship between ratcheting effect and microstructure change was discussed. The ratcheting effect in the material during current tensile-tensile fatigue loading exceeds the material's fatigue limit and the development of ratcheting strain in the material experienced three stages: initial sharp increase stage (Stage I); steady stage (Stage II); and final abrupt increase stage (Stage III). Microstructure changes in Stage I and Stage II are mainly caused by activation of basal slip system. The Extra Geometrically Necessary Dislocations (GNDs) were also calculated to discuss the relationship between the dislocation caused by the basal slip system and the ratcheting strain during the cyclic loading. In Stage III, both the basal slip and the {11-20} twins are found active during the crack propagation. The fatigue crack initiation in the AZ31B magnesium alloy is found due to the basal slip and the {11-20} tensile twins.

Keywords: AZ31B magnesium alloy; microstructure change; ratcheting strain.