Hot workability analysis of AZ61 Mg alloys with processing maps

摘要

The hot working behaviors of as-cast and homogenized AZ61 magnesium alloys were investigated using processing maps in this study. Compression tests were conducted in the temperature range of 250-450 ℃ and in the strain rate range of 1 × 10~(-3)-1 s~(-1) to establish the processing maps. The effect of homogenization heat treatment on hot workability was analyzed. The map for as-cast material exhibited a single domain of dynamic recrystallization that occurs in the temperature range of 300-450 ℃ and in the strain rate range of 1 × 10~(-3)-1 × 10~(-2) s~(-1). Homogenization heat treatment improved hot workability by expanding the workability domain and by significantly reducing the flow instability regime. Variations in power dissipation efficiency were related to the degree of dynamic recrystallization and the grain size in the workability domains for both as-cast and homogenized materials. The efficiency values generated by as-cast AZ61 were higher overall compared with those produced by homogenized AZ61 in the workability domains. The rate-controlling mechanism was dependent on the strain due to microstructural evolution.