Temperature Dependency on the Microscopic Mechanism in the Normal Direction of Wrought AZ31 Sheet under Dynamic Compressive Behavior.

Feng Zhang,Baojie Sun,Zheng Liu,Fengzheng Zhang,Mingcheng Sun,Yikui Bai

doi:10.3390/ma14237436

Abstract

In order to analyze the competitive relationship of different deformation mechanisms in wrought AZ31 magnesium alloy, the dynamic compressive experiments were conducted by a Split Hopkinson Pressure Bar (SHPB) apparatus and a resistance-heated furnace in the range of temperature between 20 and 350 °C at the strain rate of 1000 s−1. With the help of Electron Backscattered Diffraction (EBSD) observation, theoretical calculated Schmid Factor (SF), Critical Resolved Shear Stress (CRSS), and critical equivalent stress (σ0.2), the dynamic compressive deformation behavior and corresponding mechanism of wrought AZ31 magnesium alloy along the normal direction (ND) were revealed in the current study. The results demonstrate that the c-axis of grains are gradually reoriented parallel to the normal direction of wrought AZ31-ND sheet with the temperature increasing, except the dynamic recrystallization (DRX) mechanism was activated or grains grew up. The non-basal slip and tension twinning are respectively the predominant deformation mechanisms at lower temperatures (≤250 °C) and higher temperatures (≥250 °C). The predominant type of DRX mechanism of wrought AZ31-ND sheet is rotational dynamic recrystallization (RDRX), which is regarded as an obstacle for the kernel misorientation concentration region enhancement.

Highlights

The development of a wide range of structural and functional materials for energy generation, energy storage, propulsion, and automotive industry is promoted by the compelling useful need for lightweight, energy-efficient, and environmentally begin engineering systems
After discussing the activation and evolution of the microstructure deformation mechanism in wrought AZ31-normal direction (ND) sheet, such as basal slip, pyramidal slip, pyramidal slip, prismatic slip, 1012 tension twinning and 1011 contraction twinning by electron backscattered diffraction (EBSD) observation, Schmid Factors (SF) statistics, and Critical Resolved Shear Stress (CRSS) statistics, the present study provides the necessary information required to understand the complicatedly competitive relationship among the microstructure deformation mechanisms in wrought AZ31-ND sheet
In order to reveal the activation and evolution of the relevant microstructure deformation mechanism in the highly textured wrought AZ31ND sheet, in particular, to explore the complicated competitive relationship among the microstructure deformation mechanisms under elevated temperatures at a high strain rate, compressive tests were conducted along ND, which were performed at a strain rate of 1000 s−1 and among the temperature range of 20–350 ◦C

Summary

Introduction

The development of a wide range of structural and functional materials for energy generation, energy storage, propulsion, and automotive industry is promoted by the compelling useful need for lightweight, energy-efficient, and environmentally begin engineering systems. Owing to the HCP structure of wrought AZ31 magnesium alloy and due to a lack of independent slip systems, twinning is regarded as an important deformation mechanism at room temperature, which consists of 1012 tension twinning and 1011 contraction twinning [4,5], especially in high strain rate deformation. When conducting dynamic compression deformation behavior under a simultaneously high temperature and high strain rate, the deformation mechanisms of non-basal slip and twinning are unusual, resulting in a confounding, conflicting, and mechanistically unexplained phenomenon connected to the anisotropy mechanical properties of wrought AZ31 magnesium alloy with strong {0002} texture [9,10,11]. Uncovering the evolution of non-basal slip, twinning, and DRX mechanisms is the key issue regarding the weak anisotropy mechanical properties of wrought AZ31 magnesium alloy with a strong {0002} texture during dynamic compression deformation under high temperatures

Methods

Results

Conclusion