Effect of Semi- Solid Squeeze Casting Parameters on Mechanical Properties of Recycled Aluminium Alloy Scrap

Abstract

The growing demand for sustainable materials has heightened interest in recycling aluminium alloys for engineering applications. This study investigated the recycling of aluminium alloy from automobile cylinder head scrap using semi-solid squeeze casting, optimized via a Taguchi L9(3³) design. Adopted process parameters were squeeze pressure (100–140 MPa), slurry temperature (590–630 °C), and die preheating temperature (220–240 °C). Their effects on tensile strength and hardness were analyzed using signal-to-noise ratios and ANOVA. Also, the recycled alloy was identified as an Al–Si type, containing 6.75% Si and 0.36% Mg, along with trace amounts of Fe, Cu, Mn, and Zn. In addition, tensile strength ranged from 228 to 233 MPa, while hardness ranged from 72 to 78 BHN. The maximum tensile strength of 233 MPa was achieved at 100 MPa squeeze pressure, 590 °C slurry temperature, and 220 °C die preheating temperature. The maximum hardness of 78 BHN occurred at 140 MPa squeeze pressure, 630 °C slurry temperature, and 220 °C die preheating temperature. Similarly, the ANOVA revealed that die preheating temperature had the greatest influence on tensile strength (64.76% contribution), while squeeze pressure and slurry temperature most strongly affected hardness (49.57% each). Furthermore, confirmation tests at optimal parameters yielded 231 MPa tensile strength and 77 BHN hardness values comparable to those of commercial A356 alloy (258.5 MPa tensile strength, 75 BHN hardness). These findings demonstrate that Taguchi-optimized semi-solid squeeze casting can produce recycled aluminium components with excellent mechanical properties, promoting sustainable manufacturing.