Effect of Zn and Zr Concentration and Extrusion Conditions on the Mechanical Properties of Lean ZK Alloys
Compared to Al alloys Mg alloys are generally slower to extrude and this makes them expensive to process. However, making alloys easier to extrude usually equates to reduced extrudate strength. The effects of extrusion parameter, billet heat treatments and alloying element concentration on extrudability and extrudate mechanical properties are compared using four lean ZK alloys. By weight percent there was a greater increase in peak extrusion pressure and extrudate yield strength from increasing Zr than from Zn. Homogenising the extrusion billets had no effect on the lean alloys and only a minor effect on the richer alloys. Alloying element concentration has the most effect on alloy mechanical properties, while changing the extrusion speed and temperature has little influence on the extrudate mechanical properties.