At present, the investmentof magnesium alloy in China mainly adopts dry sand molding process and gypsum molding process. The shrinkage rate of magnesium alloy is high, about 1.2 times of that of aluminum, and it is easy to hot crack. The selection of dry sand mold with good yield can reduce the cracking tendency of magnesium alloy casting process. Gypsum mold has low thermal conductivity and high temperature resistance, which can play a good role in flame prevention during magnesium alloy casting. The domestic magnesium alloy gypsum mold investment casting process often uses paraffin-stearic acid low temperature wax, which is cast under the protection of gas atmosphere after dewaxing and roasting.
The future development direction of magnesium alloy investment casting in China mainly includes:
(1) Develop shell and core materials suitable for investment casting of magnesium alloy;
(2) The effects of shell properties on the surface quality and mold filling of magnesium alloy were fully studied, and the effects of shell materials and preparation process on the mechanism of magnesium alloy casting, casting/mold interface reaction and shell open-box cleaning at the end of solidification were studied;
(3) Study on the structure and properties of magnesium alloy investment castings, and the evaluation of their lifetime service performance, especially the evaluation of their long-term corrosion resistance;
(4) The development of new materials and special forming processes suitable for flame-retardant magnesium alloys for investment casting.