Effect of extrusion parameters on microstructure and mechanical properties of ZK30 Mg Alloy

Abstract

Mg alloys are the lightest structural metallic materials, and are very attractive for aerospace applications. But their applications are limited owing to their poor workability, moderate strength and poor corrosion resistance. ZK30 Mg alloy (Mg–3·0Zn–0·5Zr (wt-%)) shows better strength and workability due to the presence of fine grains than conventional Mg–Al–Zn base wrought alloys. In the present study homogenised billets of this alloy were extruded into square tubes at various temperatures and ram speeds to determine the regime of uniform deformation and best mechanical properties. Material exhibited dynamic recrystallisation under all the conditions studied. Increase in the extrusion temperature improves the homogeneity of deformation but further increase in temperature (>400°C) causes abnormal grain growth. Increase in ram speed is also found to enhance uniform deformation but further increase in ram speed (>8 mm s⁻¹) causes adiabatic heating and flow localisation. Based on the findings of the present study, an optimum process parameter regime was finalised for homogeneous deformation and best mechanical properties.