A comprehensive efficiency evaluation of conventional and ablation sand casting on the example of the AlSi7Mg alloy impeller

Abstract

Ablation sand casting is a new technology for casting aluminum alloys which helps to achieve superior cooling trends during the solidification and results in eutectic microstructure, reduced degree of defects, and improved mechanical attributes. To further enhance the functionality, water-soluble binder-based sand molds are used in conjunction with appropriate control over process parameters for specialized applications such as complex and thin-walled impeller manufacturing. In this regard, the influence of key process parameters including binder ratio (BR), sand grain fineness number (AFS number), and pouring temperature (PT) is investigated thoroughly on the mechanical characteristics (ultimate tensile strength and hardness) and dimensional accuracy of the thin-walled impeller. Ablation sand casting revealed exceptionally enhanced mechanical properties and dimensional accuracy as compared to conventional sand casting. The AFS number and binder ratio were most significant for controlling the dimensional accuracy. Multi-response optimization through Grey Relational Analysis reveals the optimal setting PT = 800 ℃, ASF number = 45, BR = 5% for lower dimensional deviation, higher hardness, and ultimate tensile strength through conventional sand casting. While for ablation case, the optimal conditions PT = 850 ℃, ASF number = 40, BR = 9% are attained against desired attributes. The attributes are significantly improved through ablated sand casting, dimensional accuracy 31.6%, hardness 58.9% and ultimate tensile strength 41.82%, and fractography analysis depicted the ductile fracture surface. The current technology is drawing attention of industry because of its potential in producing castings with superior mechanical properties and improved internal integrity.