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The basic data on the mechanical properties of a casting are frequently obtained from a tensile test, in which a suitable specimen machined from the casting is subjected to increasing axial load until it fractures. The engineering tension test is widely used by casting manufacturers as an acceptance test for customer specifications. However, tensile bars machined from castings often provide undesirable information, thereby leading one to question the part integrity. This paper, therefore, discusses the various factors that affect tensile properties obtained from specimens machined from actual castings.

Semi-solid metal (SSM) casting of aluminum components is currently establishing itself as a viable process for critical applications in the automotive industry. SSM casting processes compete favorably on both cost and performance with other casting techniques including gravity permanent mold (GPM), conventional high pressure die casting (HPDC) and squeeze casting. In this paper the various SSM casting routes in use today are reviewed. The two categories of SSM processes are thixocasting (involves the use of electro-magnetically stirred or grain-refined billets) and rheocasting (slurry produced directly from the liquid phase). The former requires a billet that needs to be reheated and processed, whereas the latter is cast directly from the liquid state. Also described here are new approaches to slurry making. These include the Slurry on Demand (SoD) process from AEMP, the Sub Liquidus Casting (SLCR) process from THT, and Diffusion Solidification.

This paper provides a description of commercially available die casting processes including conventional die casting process (high pressure, high velocity), squeeze casting (high pressure, controlled cavity fill rate), semi-solid metal casting, and Vacural™ (a variation of the conventional die casting process). The various automotive products made using these processes are also reported in the study. In this study, the mechanical (tensile, impact, fatigue strength and fracture toughness) and wear properties are compared among the above processes. Results indicate that mechanical and wear properties of aluminum alloys made using the “high integrity” casting processes (squeeze, semi-solid metal casting and Vacural™) are superior to those of conventional die castings.

The emergence of squeeze casting process for aluminum alloys has given material and design engineers a new alternative to conventional casting techniques: gravity permanent mold (GPM) and conventional (high velocity, high pressure) die casting. In recent years, the squeeze casting process has been applied to near net shape products requiring high impact strength, high fatigue strength, pressure tightness, or high wear resistance. This paper provides both a description of the HVSC squeeze casting process and examples of select components manufactured at CONTECH. In this study, the mechanical (tensile, impact, fracture toughness, fatigue strength) and wear properties of various aluminum alloy squeeze castings are also compared with those of gravity permanent mold and conventional die-castings. Results indicate that mechanical and wear properties of aluminum squeeze castings are superior to those of gravity permanent mold and conventional die-castings.