Shown below is a new application in Magsimal™-59 where a control arm is designed as a high pressure die cast part in the suspension of a sports utility vehicle (SUV).
So far this kind of part is often forged because in order to reach the desired fatigue strength. Magsimal™-59 is able to provide the necessary properties in temper F, saving an expensive heat treatment. In addition to that the part is operated without any paint coating because corrosion is not an issue at all.
In 1996 an alloy was presented from Aluminium Rheinfelden GmbH to the market which was unusual for high pressure die casting at that time: the AlMgSi-type Magsimal™-59. So far this type of alloy type had been mainly used for permanent mould casting and was especially known for its excellent resistance to corrosion even in sea water. However in addition to that it offers further properties and abilities when used in high pressure die casting which make it superior to many other alloys. The chemical composition is AlMg5Si2Mn-based. Other than most alloys for high pressure die casting Magsimal™-59 contains five to six percent Magnesium and roughly two percent of Silicon. A surplus of Magnesium and low Copper and Zinc contents maintain the excellent resistance to corrosion. Iron is kept low to keep up the elongation. Beryllium is added to reduce dross during the melting process. Together with a quick solidification a very fine microstructure consisting of an -solid solution and 40% Mg2Si-eutectic is created with superior mechanical and fatigue properties in temper F. As the fineness of the microstructure depends on the solidification velocity the geometry of the casting has huge influence on the mechanical properties.
The thinner the wall thickness is, the higher both yield strength and elongation are. At a wall thickness of 4 mm a fatigue strength of 100 MPa for tension-compression is reached.
For the designing engineer this behaviour of increasing properties with decreasing wall thickness has advantages, because a thin and light design promotes the performance of the material. However a some recommendations looking at the complexity of the design have to be taken in to account due to the higher shrinkage of this alloy type. The die design requires larger radiuses and drafts compared to an AlSi-type. None the less Magsimal™-59 with its excellent properties in temper F may substitute applications in AlSi requiring a heat treatment causing distortion and straightening of the parts.
For more information about Magsimal™-59, our other innovative products and services, visit our homepage at: www.alurheinfelden.com, or contact one of our engineers directly: Dipl.-Ing. Ralf Klos, phone: +49 7623 93-407, fax: +49 7623 93-546
Aluminium Rheinfelden GmbH
Sales and Customer Service
79618 Rheinfelden - Germany