Browse Publications Technical Papers 2002-01-0082

Production and Die Casting of Semi-Solid Magnesium Alloy AZ91D 2002-01-0082

Semi-solid forming is a relatively new process whereby an alloy with thixotropic characteristics at a temperature between solidus and liquidus is cast into a component in a mould. This technology is based on research originally carried out at MIT in the 1970s on rheological properties of semi-solid metals subjected to mechanical stirring. By not starting with a super-heated melt as in conventional liquid pressure die casting, semi-solid processing offers distinct advantages such as low cycle time, less porosity because of non-turbulent flow, improved die life and significantly better mechanical properties.
The success or failure in the production of a component largely depends on the temperature uniformity and microstructural homogeneity of the semi-solid thixotropic feedstock prior to injection. This paper describes results of work related to the preparation of AZ91D feedstock by electro-magnetic stirring combined with superheat reduction, reheating of this material to the thixotropic state by induction and semi-solid die casting a number of complex box-like components. The reheating was carried out in a single induction coil programmed to provide variable power input such that a low temperature gradient and a minimal liquid metal segregation in the billet feedstock were realized. The microstructure was monitored throughout the processing to achieve the desired semi-solid microstructure for successful die casting. The optimal casting parameters (metal temperature, ram velocity and metal pressure) for die casting the box-like components are given.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 17% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Development of Aluminum Suspension Part using by High Pressure Casting of Electro-Magnetic Stirring


View Details


Laser Welding of Aluminum Alloy Plate, Extrusion and Casting


View Details


Engineering Control for High Volume 390 Die Casting


View Details