The process for extruding magnesium wrought material is almost the same as the process for extruding aluminium materials. Most common is direct extrusion without a lubricant.
Cylindrical ingots are heated to 300-400 degrees Celsius (depending on the used alloy) and pressed through dies with manifold cross- sections. This procedure ensures a clean metallic surface and non-porous microstructures that are really important for high-tech materials and special requirements.

The maximum extrusion speed depends on the alloy that’s been used and defines the price. The two alloys that allow the highest extrusion speed are ZM 21 and AZ 31. The most difficult alloys are for example AZ 80, ZK 60 and WE 54. The extrusion speed is sometimes more than ten times slower for these alloys.

The special shapes and cross-sections of the magnesium extrusions can be designed with considerable freedom. Extruded shapes are separated into solid and hollow profiles according to the complexity factors and the cross-sections. Full rods, flatbars and shapes without embedded planes belong to the first type, while hollow profiles include one or more completely enclosed cavity or bay region.

The minimum wall thickness is determined by the alloy and form of the profile. For small or medium size profiles in alloy ZM 21 the minimum wall thickness is about 1 mm. Wall thickness in multiple walls with bosses, flanges, ribs, slits and indentations can be incorporated into a new designed product to maximize the mechanical properties.

With some of the alloys its possible to extrude magnesium on the standard dies that are normally used for aluminium extrusions with a small correction to the die. Because of this there is a wide range of standard profiles (for example flat/angle/rectangular –square and round tubes/ U-shape/H-shape etcetera) that can be extruded without big investments in new dies. The second added value for the customer is that for new designed profiles, he only needs to invest in one single die for extruding profiles in aluminium and magnesium.

After extrusion there are several steps necessary before the extruded profile can be used for constructional components with the required strength for example stretching and special heat treatment. Table 1 shows the influence of special treatment T5 compared to F state (fabrication state).