Role of processing temperature on microstructure,mechanical properties and corrosion behavior of fine grained AZ31 magnesium alloy produced by groove pressing

AZ31 magnesium alloy sheets were processed at 250 °C and 300 °C by groove pressing, a severe plastic deformation technique to achieve grain refinement. The influence of processing temperature on the evolution of microstructure, mechanical properties and corrosion behavior was studied. Groove pressing significantly reduced the grain size of the alloy from 46 μm to 6.5 μm at 250 °C processing temperature. With the higher processing temperature (300 °C), grain growth (11.4 μm) was observed for the alloy. Number of twins appeared in the groove pressed samples. Higher hardness and tensile strength were measured for the groove pressed samples processed at 250 °C without significant loss in the ductility as reflected from the % of elongation due to the grain refinement. Corrosion performance of the samples assessed by potentiodynamic polarization studies indicated increased corrosion resistance for both of the grove pressed samples. However, sample at 300 °C exhibited better corrosion resistance compared with the sample processed at 250 °C. This can be understood by considering the effect of higher processing temperature on reducing the crystal imperfections which alters the corrosion behavior.