Constitutive Equation and Hot Compression Deformation Behavior of Homogenized Al-7.5Zn-1.5Mg-0.2Cu-0.2Zr Alloy

Jianliang He; Datong Zhang; Weiweng Zhang; Cheng Qiu; Wen Zhang

doi:10.3390/ma10101193

Constitutive Equation and Hot Compression Deformation Behavior of Homogenized Al-7.5Zn-1.5Mg-0.2Cu-0.2Zr Alloy

Materials (Basel). 2017 Oct 18;10(10):1193. doi: 10.3390/ma10101193.

Authors

Jianliang He¹, Datong Zhang², Weiweng Zhang³, Cheng Qiu⁴, Wen Zhang⁵

Affiliations

¹ National Engineering Research Center of Near-Net Shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. mehejianliang@mail.scut.edu.cn.
² National Engineering Research Center of Near-Net Shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. dtzhang@scut.edu.cn.
³ National Engineering Research Center of Near-Net Shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. mewzhang@scut.edu.cn.
⁴ National Engineering Research Center of Near-Net Shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. cqiu@scut.edu.cn.
⁵ National Engineering Research Center of Near-Net Shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. jack_eei@scut.edu.cn.

Abstract

The deformation behavior of homogenized Al-7.5Zn-1.5Mg-0.2Cu-0.2Zr alloy has been studied by a set of isothermal hot compression tests, which were carried out over the temperature ranging from 350 °C to 450 °C and the strain rate ranging from 0.001 s^-1 to 10 s^-1 on Gleeble-3500 thermal simulation machine. The associated microstructure was studied using electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). The results showed that the flow stress is sensitive to strain rate and deformation temperature. The shape of true stress-strain curves obtained at a low strain rate (≤0.1 s^-1) conditions shows the characteristic of dynamic recrystallization (DRX). Two Arrhenius-typed constitutive equation without and with strain compensation were established based on the true stress-strain curves. Constitutive equation with strain compensation has more precise predictability. The main softening mechanism of the studied alloy is dynamic recovery (DRV) accompanied with DRX, particularly at deformation conditions, with low Zener-Holloman parameters.

Keywords: aluminum alloy; constitutive equation; hot compression; microstructure.