Transition in Deformation Mechanism of AZ31 Magnesium Alloy during High-Temperature Tensile Deformation

Abstract

Magnesium alloys can be used for reducing the weight of various structural products, because of their high specific strength. They have attracted considerable attention as materials with a reduced environmental load, since they help to save both resources and energy. In order to use Mg alloys for manufacturing vehicles, it is important to investigate the deformation mechanism and transition point for optimizing the material and vehicle design. In this study, we investigated the transition of the deformation mechanism during the high-temperature uniaxial tensile deformation of the AZ31 Mg alloy. At a test temperature of 523 K and an initial strain rate of 3 × 10 −3 s −1 , the AZ31 Mg alloy (mean grain size: ∼5 μm) exhibited stable deformation behavior and the deformation mechanism changed to one dominated by grain boundary sliding.

On the Role of Hollow Aluminium Oxide Microballoons during Machining of AZ31 Magnesium Syntactic Foam

“…Moreover, at high (Davg/h) ratios, high cutting temperatures are estimated (350 °C) due to tool rubbing leading to higher values of equivalent plastic strain and chip compression ratio. It can be inferred through the literature findings [ 40 , 41 ] that the twinning mechanism which dominates the magnesium matrix plasticity during lower plastic strain is replaced by dislocation slip mechanisms (such as prismatic/pyramidal slip) at a higher equivalent plastic strain. This transition in magnesium plastic deformation from twinning to dislocation slip mechanism at lower cutting feed is expected to be associated with a drop in shear stress values with increasing cutting temperature in the primary shear zone ( Figure 3 d).…”

“…As dynamic strain rate increases with cutting speed, the rate of twin nucleation, and subsequent increase in the volume fraction of twins in the magnesium matrix along the shear zone builds up. However, after a critical density of the twin population is reached, the plastic deformation in the matrix acts as an obstruction to the twin nucleation and growth via the grain boundaries [40,41]. Given the orientation of twins being less resistant to the prismatic slip leads to a transition from the dominant twinning mechanism to prismatic slip along the grain boundaries.…”

“…The twin volume fraction grows to a certain extent and cannot be limited anymore within the magnesium grains. With cutting temperature rising in the shear zone, this forces yielding of the magnesium matrix through a transition in deformation mechanism from mechanical twinning to dislocation slip [40]. At this stage, when the matrix starts deforming plastically, the bubbles carry the load through an effective load transfer via the interface, thus unloading the matrix.…”

Establishment of Thermal Ductile Fracture Criterion for As‐Cast 42CrMo Steel and Its Application in Hot Ring Rolling Process

“…With the increase of strain, dynamic recovery and recrystallization play a softening role, and the increase rate of flow stress slows down. en, the stress reaches a maximum, after which the softening effect is dominant, the tensile specimen breaks, and the stress decreases [25,26]. (2) Curves with no significant peak: when the specimens were tested at the high temperature and low strain rate (e.g., at 1423 K or 1473 K and 0.001 s − 1 ), work hardening dominates and stress values increase rapidly during the initial stages.…”