Enhancing the strength of rolled ZK60 alloys via the combined use of twinning deformation and aging treatment

Abstract

This study aims to exploit the possibility of combining twinning deformation and aging treatments to enhance the strength of age-hardenable Mg alloys. It was found that the yield strength of ZK60 hot-rolled alloys can be more effectively enhanced by the combined use of pre-compression along the transverse direction (TD) and aging treatments compared to direct aging. The yield strength of ZK60 hot-rolled alloys was enhanced by 73±8MPa by the combined use of pre-compression 3.5% along the TD and aging treatments, while the separated use of pre-compression 3.5% or aging treatments only increased the yield strength by 32±6 or 38±6MPa. It was confirmed that a large number of extension twins were generated during the pre-compression along the TD at room temperature, which led to the grain refinement strengthening. Moreover, it is found that the twin boundaries in addition to grain boundaries, can serve as the favorable sites for the nucleation of precipitates. The effect of the processing sequence (pre-compression 3.5% and aging treatment) on the yield strength was also examined, which was found negligible for the present ZK60 alloys. Nevertheless, the experimental results positively proved the idea of enhancing the yield strength of age-hardenable Mg alloys by the combined use of twinning deformation and aging treatments.