Properties of sand-cast magnesium alloys

The influence of pouring temperature and holding time before pouring on the mechanical properties .and chemical composition of several magnesium casting alloys has been investigated and the results, obtained on sand-cast four-bar moulds, are reported in the present report. The pouring temperature was varied from 700°C (1290°F) to 850°C (1560°F) and the holding time from 10 min to 2 hr at normal pouring temperature. Other melts were held at 700°C or 850°C for 30 min before pouring. In general these various treatments did not adversely affect the chemical composition and mechanical properties to a pronounced extent. However, because alloy ZH62 tends to form dross when heated to 850°C, such a high temperature should be avoided if possible. The "insoluble" zirconium content of zirconium-containing alloys may be appreciably decreased by lowering the melt temperature to 700°C. The "soluble" zirconium and rare earth contents of alloy QE22, the rare earth content of alloy EZ33 and the thorium content of alloy ZH62 may be decreased by holding the melt at normal pouring temperature for an appreciable length of time.