Elevated temperature tensile behavior of extruded magnesium plates

The elevated temperature tensile behavior of AZ31, AM50, ZM21, ZK10, and ZK30 direct extruded magnesium sheets was investigated. Uniaxial tensile testing to failure and step strain rate testing were performed at 400°C and 450°C to determine the effect of alloy composition and microstructure on elevated temperature ductility, strain rate sensitivity, and fracture behavior. Ductilities of almost 300% were observed in the as-extruded material with the ZK alloys giving the highest ductility. The high ductility of the ZK materials was due, in part, to their ability to maintain a relatively fine grain size throughout tensile testing. The stress exponent, n, for dislocation creep was affected by aluminum content as was the amount of grain boundary sliding. These results will be discussed in the context of designing improved alloys for elevated temperature forming processes.