Creep deformation behaviour of AZ31 magnesium alloy over wide range of temperature and stress

Abstract

The creep deformation behaviour of coarse grained AZ31 magnesium alloy was examined in the temperature range from 423 to 673 K (0·46–0·73Tm) under various constant stresses covering low strain rate range from 4×10−9 to 2×10−2 s−1. Most shape of the creep curve was typical of class II behaviour. However, only at low stress and low temperature, the shape of the creep curve was typical of class I behaviour. At very low stress at 673 K, the stress exponent for the secondary creep rate was ∼2. At low stress level, the stress exponent was ∼3 and the present results were in good agreement with the prediction of Takeuchi and Argon model. At high stress level, the stress exponent was ∼5 and the present results were in good agreement with the prediction of Weertman model. The transition of deformation mechanism from solute drag creep to dislocation climb creep could be explained in terms of solute atmosphere breakaway concept.