Time-dependent uniaxial behavior of rolled magnesium alloy AZ31B at 393 K and room temperature
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Time-dependent uniaxial behavior of rolled magnesium alloy AZ31B at 393 K and room temperature Li Meng1,2,3 · Wufan Chen4 · Vincent de Greef3 · Miaolin Feng1
Received: 23 February 2020 / Accepted: 19 November 2020 © The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature 2020
Abstract To address the time-dependent properties of rolled AZ31B alloy, we conducted typical tests of the rate jump, creep, and stress relaxation at room temperature and 393 K. In the rate jump tests, the tensile curve exhibited a strong dependence on the strain rate, whereas compression was totally insensitive to the stress rate at both temperatures. For the creep and stress relaxation test, we observed creep strain and decay stress in the compression, which was weaker than the tensile curve. The plastic viscosity increased at 393 K because the dislocation motion was thermally activated. We then applied thermal activation theory for the repeated stress relaxation tests. The activation volume implies that cross-slip and dislocation nucleation are the operating mechanisms for creep and stress relaxation. Keywords Magnesium alloy AZ31B · Time-dependent · Rate jump · Creep · Stress relaxation · Thermal activation
1 Introduction Magnesium (Mg) alloys have drawn much attention from researchers due to their high strength-to-weight ratio and the excellent potential to reduce structure weight and energy consumption. However, the underlying deformation mechanisms of Mg alloys are not easy
B W. Chen
[email protected]
B M. Feng
[email protected]
1
School of Naval Architecture, Ocean and Civil Engineering (State Key Laboratory of Ocean Engineering), Shanghai Jiao Tong University, 200240 Shanghai, China
2
The University of Michigan-Shanghai Jiao Tong University Joint Institute (UM-SJTU JI), Shanghai Jiao Tong University, 200240 Shanghai, China
3
Laboratoire de Mécanique des Solides, CNRS UMR 7649, Ecole Polytechnique, 91128 Palaiseau, France
4
Institute of Applied Mechanics, School of Aeronautics and Astronautics, Zhejiang University, 310058, Hangzhou, China
Mech Time-Depend Mater
to understand, as the hexagonal closed packed (hcp) structure exhibits strong asymmetry under tensile and compressive load. According to the Taylor criterion (Taylor 1938), there must be at least five independent systems to accommodate ductility and plastic deformation, thus {10-12} extension twinning, and {10-11} contraction twins would occur (Nave and Barnett 2004). Plenty of experimental and modeling work has studied the deformation mechanisms of AZ31 alloys (Agnew and Duygulu 2005; Li et al. 2010; Wang et al. 2015; Kim et al. 2008; He et al. 2017; Wu et al. 2017; Jiang et al. 2008; Jia and Bai 2016; Kang et al. 2014; Meng et al. 2019; Gzyl et al. 2015; Xu et al. 2015; Koller et al. 2015). It is known that materials’ time-dependent properties, such as loading rate sensitivity, creep and stress relaxation, are important to engineering applications and strongly affected by ambient temperature (Meng et al. 2019; Karimi et al. 201
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