Light alloys of aluminum (Al), magnesium (Mg) and titanium (Ti) are increasingly being used in transportation and manufacturing industries to reduce energy consumption as well as carbon footprint. Fig. 1 (DuckerFrontier, 2020) shows that the use of Al in the automotive sector has seen tremendous growth; from 84 pounds per vehicle in 1975–459 pounds in 2020 and 570 pounds forecast for 2030, with majority of the Al use being castings. All sectors of manufacturing of light alloys have experienced significant growth and particularly the metal casting industry.
The first casting of metals (gold) can actually be traced to around 4000 BCE, although a copper frog is the oldest existing casting currently known dating to around 3200 BCE (Olsen, 2020). Modern casting technologies are providing components in practically every industrial application notwithstanding solidification is the starting point for every wrought or powder product for downstream manufacturing. Annual global metal casting production was about 109 million metric tons in 2019, including about 17,205,447 metric tons (MT) of aluminum and 60,138 MT of magnesium (Staff Report, 2021). The top-five casting producing countries are China, India, USA, Japan and Germany. The metal casting industry is a foundational pillar to essentially all manufacturing activities, and light alloy casting technologies are critical to the sustainability of manufacturing and transportation industries around the world.
Conventional cast Al, Mg and Ti alloys and their melting and casting processes are well documented in ASM handbooks (Avedesian and Baker, 1999, Viswanathan et al., 2008, Anderson et al., 2018), and several monographs on aluminum (Kaufman and Rooy, 2004), magnesium (Sahoo, 2011) and titanium (Lütjering and Williams, 2007). Solidification fundamentals for cast alloys and conventional casting process technologies have been documented in several books published since 1960 s (Chalmers, 1964, Flemings, 1974, Kurz and Fisher, 1984, Stefanescu, 2002, Dantzig and Rappaz, 2009). Thus, conventional cast alloys and casting process techniques are not reviewed in this paper. A recent review by Campbell (2020) provided a critical assessment of various casting processes in terms of defect formation specifically bifilms and cracks in castings as well as their negative effects on mechanical properties of castings.
Here we provide a comprehensive and yet critical review of the developments and innovations that have emerged the last two decades in light alloy design, casting technologies and emerging solidification-based processes, focusing on process improvements to overcome some fundamental issues related to defect formation in conventional casting processes. In addition, we review future trends such as casting simulation, multi-material design and manufacturing, additive manufacturing, and the applications of Integrated Computational Materials Engineering (ICME) in alloy design, manufacturing and product development.
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