Magnesium castings characterized by good surface appearance and high strength to weight ratio can be obtained in a wide variety of intricate shapes. Sand, permanent mold and die-casting are the methods most commonly used to produce cast structures.
The selection of a proper alloy for a particular use depends upon the service requirements of the job as well as relative properties and characteristics of the casting alloy. The most common casting alloys are AZ91D, AZ91B, AM50A and AM60B. AZ91D is the most common alloy used in high pressure die casting.
This alloy offers good strength/weight ratio and excellent cast ability. AM50A & AM60B are used for safety components in the automotive industry. Good ductility and energy absorbing properties combined with good strength and castability are among their properties. AM20 is another Mg-Al alloy used for special safety components that offers high ductility and impact strengths.
Magnesium alloys are readily extruded into an almost unlimited variety of round rods, bars, tubes, structural shapes. The process for extruding magnesium is almost the same as the process for extruding aluminum materials. Most common is direct extrusion without a lubricant. Cylindrical ingots are heated to 300-4000C and pressed through dies.
With some of the alloys it is possible to extrude magnesium on the standard dies that are normally used for aluminum extrusions with a small correction to the die. Because of this there is a wide range of standard profiles that can be extruded without big investments in new dies. The second added value for the customer is that for new designed profiles, it is only required to invest in one single die for extruding profiles in aluminum and magnesium. Generally extrusion speed for Magnesium is much slower than for Aluminum.