한국주조공학회

To prevent oxidation of Mg melt, SF6 gas has been generally used for Mg alloys during melting and casting as a cover gas. The use of SF6 gas, however, will be restricted owing to its crucial impact on global warming. Non-SF6 process during melting and casting in diecasting industry has been proved with Eco-Mg alloys by a simple addition of small amount of CaO into Mg alloys. This paper shows non-SF6 diecasting procedures for 0.7wt% CaO added AZ91D Eco-Mg alloys. Cold- chamber diecasting was performed under CO2 atmosphere without SF6 gas. An increment of mechanical properties, especially strength and ductility of Eco-Mg alloys is, in part, due to high- quality melt, refined grain size and Al2Ca second phase strengthening. Microstructures and mechanical properties of 0.7wt% CaO added AZ91D Eco-Mg alloys are evaluated in comparison with those of conventional AZ91D Mg alloy.

AZ91D, CaO, Eco-Mg, Non-SF6 process, Strength, Elongation.