Microstructure and Mechanical Properties of AZ31B Magnesium Alloy Prepared by Solid State Recycling

Machined chips of AZ31B magnesium alloy were consolidated by cold pressing followed by hot extruding at different processing temperatures and extrusion ratios. Compared with ingot extruding alloy, the influences of processing technique on mechanical properties of recycled alloys were analyzed from two main aspects involving the dynamic recrystallization microstructure and the bonding condition between chips. Results show that with the increasing extrusion temperature, the ultimate tensile strength and elongation to failure of the recycled alloys firstly increase and then decrease. The combined action of grain growth and improvement of the bonding between chips with the increasing extrusion temperature results in the variations of mechanical properties of the recycled alloy. With the extrusion ratio increasing from 4:1 to 44:1, the grain is refined, and the bonding between chips is enhanced. This contributes to the increased ultimate tensile strength of recycled alloy. Whereas elongation to failure decreases when extrusion ratio is higher than 25:1 due to the significant deformation strengthening.