Formability of Wrought Magnesium Alloys by Hot Compression Testing and Laboratory-Scale Extrusion

The present study is aimed at investigating the high-temperature behaviour of commercially available alloys under conditions of interest for their extrusion. The AZ31B and ZM21 alloys were studied by hot compression testing in the temperature range 320-450 degrees C (selecting four different levels for each alloy, depending on its composition) and at four values of initial strain rates, lying in the range 5.56. 10(-4) s(-1) -2.78. 10(-2) s(-1). A laboratory-scale extrusion rig was also adopted to produce extrudates in the form of bars and hollow tubes (external diameters from 8 down to 4 mm) according to the optimized parameters defined by the hot compression tests. Microstructural analyses were carried out to deeply investigate the evolution of microstructure during extrusion and to draw comparisons among hot compressed and extruded samples.