The quantitative effects of temperature and cumulative strain on the mechanical properties of hot-extruded AZ80 Mg alloy during multi-directional forging

There is still a lack of quantitative reports on the effects of temperature and strain on the mechanical properties of Mg alloy forgings. In order to investigate the quantitative effects of temperature and cumulative strain on the mechanical properties of AZ80 Mg alloy during multi-directional forging (MDF), samples of the extruded alloy were multi-directionally forged (MDFed) at 380 degrees C, 280 degrees C and 180 degrees C with cumulative strain of 0.6 and MDFed at 180 degrees C with cumulative strains of 0.6, 1.2, 1.8 and 2.4. The microstructure and mechanical properties of the extruded alloy after MDF under different conditions were analyzed. The results show that MDF at different temperatures changes the mechanical properties of the alloy by affecting grain size, precipitates content and dislocation density. The higher yield strength (YS) and ultimate tensile strength (UTS) can be attained by MDF at lower temperature, but the YS and UTS are not sensitive to the cumulative strain when MDF at 180 degrees C. More coarse precipitates reduce the mechanical properties with the increase of the cumulative strain applied by MDF at 180 degrees C. The best balance of mechanical properties was attained after MDF at 180 degrees C with the cumulative strain of 0.6. In this case, the YS, UTS (Engineering stress) and elongation of the AZ80 Mg alloy were 298.4 MPa, 402.1 MPa and 17.7%, which is mainly attributed to the formation of a bimodal microstructure.

Automated summary

The study shows that temperature and cumulative strain have significant effects on the mechanical properties of AZ80 Mg alloy, with lower temperature multi-directional forging leading to higher yield strength and ultimate tensile strength. By applying appropriate multi-directional forging temperature and cumulative strain, the best balance of mechanical properties can be achieved.