Peng Gong, Xin Cui, Y Zhang, Liandi Xu, Bo Zhang, Rui Xue, Danyang Liu, Xuelei Song, Xu Yan, Changhe Li
To achieve extreme weight reduction in new energy vehicles, the deep integration of intelligent equipment with lightweighting strategies has catalyzed a paradigm shift. Light alloys, particularly aluminum and magnesium, have become pivotal materials. Compared to traditional high pressure die casting, integrated giga-casting demonstrates significant advancements, pushing the flow length-to-thickness ratio beyond 500 and requiring clamping forces exceeding 16,000 tons. Nevertheless, the complex physical metallurgy of large-scale structures remains insufficiently understood, which limits the formulation of process specifications and widespread industrial application. Particularly in chaotic filling environments, the intrinsic trade-offs among melt fluidity, solidification shrinkage, and mechanical integrity are difficult to control. To address these challenges, a comprehensive assessment of microstructural evolution and strengthening mechanisms under rapid solidification conditions is provided. Firstly, this paper reveals advanced strengthening mechanisms by detailing the decisive role of casting densification and nonequilibrium solute trapping in activating grain refinement, solid solution strengthening, and unique deformation twinning. Secondly, the distinctive technological evolution towards intelligent casting routes is clarified, demonstrating how thermal management and semi-solid technologies suppress internal porosity below 1.7 % and elevate the ultimate tensile strength to the 250-450 MPa range. Furthermore, process optimization strategies are summarized based on material-process-intelligence synergy, including in situ sensing, millisecond-level artificial intelligence defect prediction, and digital twin frameworks. Finally, future development directions are outlined. This review aims to facilitate a deeper understanding of the underlying mechanisms, assist in formulating process specifications, and ultimately achieve a weight reduction of 15 – 20 % for automotive structures.