Influence of Post-ECAP TMT on Mechanical Properties of the Wrought Magnesium Alloy AZ80

It is well-known that the high-cycle fatigue (HCF) performance of severe plastically deformed wrought magnesium alloys is not as good as one might expect from the significant grain size refinement. Although enhanced HCF strength after ECAP as compared to as-cast material was observed its value was significantly lower than after conventional extruding. The present investigation was undertaken to determine whether the relatively poor HCF strength of the ECAP processed wrought magnesium alloy AZ80 is associated with the ECAP-induced unfavorable crystallographic textures. Post-ECAP thermo-mechanical treatment (TMT) was found to result in favorable texture modifications as well as in markedly improved HCF performance. The proposed novel technique consists of a not yet used combination of severe plastic deformation via ECAP followed by a 1-step swaging process. It is shown that the resulting combination of both ultrafinegrain sized material and beneficial crystallographic texture results in superior HCF performance not achievable by ECAP-processing alone.