Effects of Filling Pressure on Microstructure and Tensile Properties of Gypsum Mold Counter Gravity Casted ZM5 Magnesium Alloy

ZM5 magnesium alloy was prepared at different filling presures by combining gypsum mould and counter gravity casting process, and the effects of filling pressure on filling ability of thin-wall casting, microstructure and tensile properties of as-cast magnesium alloy were studied. At last, the optimal casting parameters were obtained. The results show that, with the increase of filling pressure, the casting microstructure was obviously refined. The optimal filling pressure with maximum tensile properties was 40 kPa at which the filling ability of the thin-wall casting was better and tensile strength was (192±5) MPa, elongation was (1.5±0.2)%. The casting process with preheating temperature of 330-350 ℃, pouring temperature of 730-750 ℃ and filling pressure of 35-40 kPa can meet the need of thin-wall castings of magnesium alloy.