EFFECT OF HPT PROCESSING TEMPERATURE ON STRENGTH OF A Mg-Al-Zn ALLOY

Severe plastic deformation has been used widely to refine the grain structure and enhance the strength of magnesium alloys. However, the processing of these materials by Equal-Channel Angular Pressing is usually conducted at temperatures in the range from 423 to 523K due to the limited ductility available in these alloys at low temperatures. In practice, this relatively high processing temperature leads to the occurrence of recovery and recrystallization in these materials. An alternative approach is to process the alloys by High-Pressure Torsion (HPT) because the imposition of a high hydrostatic pressure provides an opportunity for processing at significantly lower temperatures. The present investigation was initiated to evaluate the evolution of hardness and microstructure in an AZ31 alloy processed by HPT at temperatures in the range from 296 to 473K.