Mechanical Behavior of AZ31B Mg Alloy Sheets under Monotonic and Cyclic Loadings at Room and Moderately Elevated Temperatures

Abstract

Large-strain monotonic and cyclic loading tests of AZ31B magnesium alloy sheets were performed with a newly developed testing system, at different temperatures, ranging from room temperature to 250 °C. Behaviors showing significant twinning during initial in-plane compression and untwinning in subsequent tension at and slightly above room temperature were recorded. Strong yielding asymmetry and nonlinear hardening behavior were also revealed. Considerable Bauschinger effects, transient behavior, and variable permanent softening responses were observed near room temperature, but these were reduced and almost disappeared as the temperature increased. Different stress–strain responses were inherent to the activation of twinning at lower temperatures and non-basal slip systems at elevated temperatures. A critical temperature was identified to account for the transition between the twinning-dominant and slip-dominant deformation mechanisms. Accordingly, below the transition point, stress–strain curves of cyclic loading tests exhibited concave-up shapes for compression or compression following tension, and an unusual S-shape for tension following compression. This unusual shape disappeared when the temperature was above the transition point. Shrinkage of the elastic range and variation in Young’s modulus due to plastic strain deformation during stress reversals were also observed. The texture-induced anisotropy of both the elastic and plastic behaviors was characterized experimentally.

Verification of Equation for Evaluating Dislocation Density during Steady-state Creep of Metals

“…The magnitude of the applied stress is then generalized by the proof stress at a certain temperature. The values of for most heat-resistant steels at high temperatures are documented in data sheets published by the NIMS (2.25Cr-1Mo, 1986a;Type 304, 1986b;1Cr-0.5Mo, 1996;Alloy 800, 1998;Type 316, 2000;Gr.91, 2007 (Sharafat, Martinez, & Ghoniem, 1999), TZM (Mrotzek, Hoffmann, Martin, & Oettel, 2007), CP-Ti (Japan Institute of Metals, 1993), and AZ31 (Nguyen et al, 2014), the cited references were used. The values of at high temperatures of Ge were not found.…”

Anisotropic mechanical behavior of semi‐crystalline polymers: Characterization and modeling of non‐monotonic loading including damage

“…Therefore, the evolution of apparent Young's modulus with respect to axial strain can be characterized by measuring the slopes of unloading–reloading as the strain increases, as widely reported for highly nonlinear materials during cyclic loading (e.g., Refs. , and ).…”

Characteristics of magnesium AZ31 alloys subjected to high speed rolling

“…The observed increase in the size of the DRX Table 2 Rolling parameters and mean strain rates calculated by the relation of Ford and Alexander [14]. Table 3 The mean flow stresses in the rolling mill estimated from the work of Nguyen et al [27] and Ishikawa and Watanabe [28] for HSR and LSR rolling. grains with increasing reductions during HSR can in turn be associated with the increase in the deformation temperature.…”