Abstract

The microstructure evolution and the mechanical behavior of Al–4.8Mg alloy were investigated by means of isothermal compression tests at various temperatures (280–520 °C) and strain rates (0.01–10 s−1). The results shown that there are three main mechanisms of dynamic softening of samples within the range of selected process parameters: dynamic recovery, dynamic recovery + dynamic recrystallization, and dynamic recrystallization, and the equiaxed dynamic recrystallization grain tends to be formed under higher temperature and higher strain rate. In order to accurately describe the dynamic recrystallization condition of Al-4.8Mg alloy under a wide range of hot deformation parameters, an improved dynamic recrystallization critical conditions model is proposed based on deformation activation energy and work-hardening rate. Additionally, a two–stage physically constitutive model considering the influence of work hardening–dynamic recovery and dynamic recrystallization is established. Comparisons between the predicted and experimental data indicate that the proposed model can adequately predict the flow stress in the range of selected process parameters with the average absolute relative error of 4.02%.

Highlights

  • Due to their characteristics of light weight, reasonable strength, good formability and high corrosion resistance, Al-Mg alloys are widely used in transportation, architectural decoration, food packaging and other industrial fields [1,2,3]

  • In the whole range of selected process parameters, if no DRX occurred in the material, the physical constitution based on dynamic recovery (DRV) was used to describe the deformation behavior of the material

  • The flow stress decreases with the increasing of the temperature at the given strain rate, while

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Summary

Introduction

Due to their characteristics of light weight, reasonable strength, good formability and high corrosion resistance, Al-Mg alloys are widely used in transportation, architectural decoration, food packaging and other industrial fields [1,2,3]. In the whole range of selected process parameters, if no DRX occurred in the material, the physical constitution based on DRV was used to describe the deformation behavior of the material. Such as, the deformation behavior of 5754 aluminum alloy reported by Huang [21]. When DRX occurs in the whole range of selected process parameters, as reported in Al-Li alloy [22], the inflection point of θ–σ curve is used to obtain the critical strain of DRX (θ is the work hardening rate). DRV and DRX mechanisms is established to describe the relationship between the flow stress and forming parameters

Materials and Experiments
Original
Results
Microstructural Evolution
Microstructural
Optical microstructure of the
DRX Critical Conditions
Determination of Critical Temperature and Strain Rate
The lnZ of
33.5 Z parameter
Determination of Critical Strain
Physically–Based Constitutive Model of Flow Stress
Verification of the Constitutive Model
N σand parameters

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