Improvements in microstructure and mechanical properties of AZ80 magnesium alloy by means of an efficient, novel severe plastic deformation process

• H-Tube pressing (HTP) is proposed as a novel SPD technique for tubular specimens.
• UTS, yield stress, and elongation were increased by more than 90% after conducting a half-cycle HTP.
• A single-pass HTP was able to effectively decrease the average grain size of AZ80 from 79 to 11 μm.
• HTP can be employed as a single-pass SPD operation due to imposing outstanding amount of plastic strain.

Present paper includes efforts to develop dual equal channel lateral extrusion (DECLE) into an efficient SPD technique for processing tubular samples. In modified technique, entitled H-tube pressing (HTP), specimen accumulates outstanding amount of plastic strain in a couple of half cycles. Theoretically imposed plastic strain by means of the HTP operation exceeds that is attainable via a wide range of SPD methods. In this research work, the HTP process was experimentally conducted up to 2 passes (4 half cycles) on as-cast AZ80 magnesium alloy at elevated temperature. The microstructural and mechanical improvements follow the HTP process were investigated. Findings revealed that by conducting the first half cycle of HTP process, the average grain size reduced by 73%. Moreover, the yield stress and the elongation were increased by 90% compared to as-cast condition while the ultimate tensile strength and the microhardness were improved by 100 and 58%, respectively. Stability of mechanical properties of AZ80 alloy was observed at the end of the first half cycle. These results imply that HTP can be employed as an efficient, single-pass operation.

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