Study of fractional softening of AZ31 magnesium alloy under multistage hot deformation

Abstract

In the present study flow softening behaviour of AZ31 magnesium alloy was investigated by double hit compression tests in the temperature range 250–400°C and strain rate range 10^–3–10^–1 s^–1. The tests were conducted with delay times varying 4–250 s after achieving the critical strain ϵ_c in each deformation condition. It has been found that static restoration processes (recovery and recrystallisation) were intensely depended on strain rate and deformation temperature. Fractional softening values increased with increasing strain rate and deformation temperature. Accordingly the softening curves were divided into three regions. The softening in the short interpass times was attributed to the occurrence of static recovery and followed by static recrystallisation and grain growth as dominant softening mechanisms for the second and third regions respectively. In addition static recrystallisation kinetics was interpreted by Avrami equation. Analysis of the results indicated that Avrami constant was changed by varying temperature.

Keywords

AZ31 MAGNESIUM ALLOY DOUBLE HIT COMPRESSION FRACTIONAL SOFTENING STATIC RESTORATION PROCESS

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