Impact of Melt Thermal Treatment and Artificial Aging on Microstructure and Mechanical Properties of A356 Alloy

This paper presents the individual and the combined impact of melt thermal treatment and artificial aging treatment on microstructure and mechanical properties of A356 alloy. Samples modified with and without strontium (Sr)-based master alloy are also prepared for comparison purposes. The as-cast results for melt thermal treatment processed alloys displayed the refinement of alpha-Al grains coupled with a drop in eutectic silicon length. Further treatment results of artificial aging treatment alter eutectic silicon morphology into a spherical shape, and distribution of alpha-Al and eutectic silicon phase improves significantly compared to as-cast A356 alloys. The best eutectic silicon modification in terms of aspect ratio and roundness is obtained in the case of aged A356 alloy processed through melt thermal treatment along with Sr modifier. Because of this improvement in eutectic Si characteristics, the ultimate tensile strength, elongation, and hardness of the aged A356 alloy treated through melt thermal treatment along with Sr modifier increased by 9.6%, 24.4%, and 10.1%, respectively, compared to the aged untreated alloy. DSC results show that a maximum shift in eutectic peak temperature is observed in the melt thermal treatment along with Sr modifier A356 alloy.