Effect of hot working and aging heat treatments on monotonic, cyclic, and fatigue behavior of WE43 magnesium alloy

Abstract

This paper examines monotonic and cyclic behavior of WE43 alloy in several conditions including direct-chill as-cast and rolled heat-treated with an emphasis on the comparison of microstructural features governing the difference in their behavior. To facilitate the evaluation of the effect of hot working conditions on the material behavior, the as-cast-WE43 was converted into two rolled plates with one (P2) being rolled at a temperature for 16.5 °C lower than the other plate (P1). The plates were further processed into T5 and T6 conditions. The plate P2 in the T5 condition was found to have the highest strength and elongation to fracture in tension along both the rolling direction (RD) and the transverse direction (TD). The other plate, P1, showed a higher ductility in compression, while exhibiting slightly lower strength and elongation in tension. The trend of lower strength and elongation in tension with higher ductility in compression continued to the material in the T6 condition and finally to the as-cast material. Strain to fracture in compression was the largest for the as-cast material. In addition to quasi-static strength, P2 was found to exhibit superior low cyclic fatigue (LCF) and high cyclic fatigue (HCF) behavior. Consistent with the quasi-static strength, the rolled plates in the T5 conditions exhibited slightly longer lives in LCF and HCF along TD than along RD. The interesting deformation behavior characteristics of the alloy in different conditions are rationalized in terms of their microstructures. The results reveal that it is possible to further optimize the hot working conditions to obtain the alloy WE43 exhibiting better performance characteristics.