Modelling the Mechanical Attributes (Roughness, Strength, and Hardness) of Al-alloy A356 during Sand Casting

• Published in: Materials Vol. 13; no. 3; p. 598
• Main Authors: Ishfaq, Kashif, Ali, Muhammad Asad, Ahmad, Naveed, Zahoor, Sadaf, Al-Ahmari, Abdulrahman M, Hafeez, Faisal
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.01.2020; MDPI
• Subjects: a356-alloy; Alloys; Aluminum base alloys; Casting; Casting alloys; Castings; Empirical analysis; Hardness; Impact strength; Low temperature; Manufacturing; Mechanical properties; Microcracks; Moisture content; Optimization; Permeability; Porosity; Pouring; pouring temperature; pouring velocity; Response surface methodology; response surface methodology (rsm); roughness; Sand casting; scanning electron microscopic analysis; Solidification; strength; Surface roughness; Tensile strength; Ultimate tensile strength; hardness; strength; roughness; scanning electron microscopic analysis; A356-alloy; pouring velocity; pouring temperature; moisture content; response surface methodology (RSM)
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma13030598

Sand-casting is a well established primary process for manufacturing various parts of A356 alloy. However, the quality of the casting is adversely affected by the change in the magnitude of the control variables. For instance, a larger magnitude of pouring velocity induces a drop effect and a lower velocity increases the likelihood of cold-shut and mis-run types of defects. Similarly, a high pouring temperature causes the formation of hot tears, whereas a low temperature is a source of premature solidification. Likewise, a higher moisture content yields microcracks (due to gas shrinkages) in the casting and a lower moisture content results in the poor strength of the mold. Therefore, the appropriate selection of control variables is essential to ensure quality manufactured products. The empirical relations could provide valuable guidance in this regard. Additionally, although the casting process was optimized for A356 alloy, it was mostly done for a single response. Therefore, this paper aimed to formulate empirical relations for the contradictory responses, i.e., hardness, ultimate tensile strength and surface roughness, using the response surface methodology. The experimental results were comprehensively analyzed using statistical and scanning electron microscopic analyses. Optimized parameters were proposed and validated to achieve castings with high hardness (84.5 HB) and strength (153.5 MPa) with minimum roughness (5.8 µm).