Effect of Prior Deformation on Creep Behavior of a Die-Cast Mg-Al-Ca Alloy

Abstract

The creep of die-cast Mg-Al-Ca alloys is characterized by the pronounced decrease in creep rate during the transient region. Higher creep rates immediately after the stress application for the alloys can result in the degradation of bolt-load retention in the automotive powertrain applications. In this study, the effect of prior deformation on creep behavior was investigated for the Mg-Al-Ca AX51 (X representing calcium) die-cast alloy, where the prior deformation was introduced by using the creep machine at temperatures of 423 and 473 K. The creep curves of the specimens with the prior deformation were compared with that of the as die-cast specimen at the creep testing condition of 423 K and 80 MPa. It was found that the prior deformation introduced by the creep machine is not effective to decrease the creep rates for the alloy. The obtained results of creep behavior are discussed on the basis of dislocation movements during creep.