Two casting methods are used to fabricate these automobile wheels: gravity permanent mold casting (GPMC) and low-pressure diecasting (LPDC). LPDC is the favored process since it has higher metal yield and more productivity due to a faster cycle time compared to the GPMC process. In addition, the LPDC process provides better casting quality when the parts are solidified under pressure. The goal of this GM/SJTU collaborative project is to develop magnesium alloys and optimize the low pressure die casting process for lightweight magnesium wheel applications. This paper summarizes numerical simulation and process development for low-pressure die casting of magnesium alloy wheels using a rare-earth-containing high-strength magnesium alloy, NZK (Mg-3Nd-0.2Zn-0.4Zr), recently developed by Shanghai Jiao Tong University. Wheels made from this alloy are compared with commercial AZ81 alloy (Mg-8Al-1Zn), which has higher ductility than commercial AZ91 alloy. The effect of die filling time, die temperature, casting temperature and the use of cooling system on filling and solidification sequence of magnesium wheel casting was simulated. Potential defects, such as shrinkage porosity at the rim-spoke junctions, were predicted by simulation and validated by casting trials. The use of cooling system was found to be effective in reducing the shrinkage, based on the simulation results and casting experiments. The tensile properties of NZK-T6 alloy wheels meet the GM specification for cast aluminum or magnesium wheels. The wheel bench test results suggest that NZK-T6 alloy wheels can meet the structural and fatigue requirements of automobile wheels.
Numerical simulation and process development for low pressure diecasting of magnesium alloy wheels
Numerische Simulation und Prozessentwicklung für den Niederdruck-Kokillenguss zur Herstellung von Fahrzeugfelgen aus Magnesiumlegierungen
2010
8 Seiten, 16 Bilder, 13 Tabellen, 11 Quellen
Aufsatz (Konferenz)
Englisch
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