Development of Aluminum Casting and FSW Technologies for Next-Generation Automotive Powertrains

随着提高汽车燃油效率的努力，铝（Al）合金是汽车动力总成部件的潜在候选者，如电动汽车的发动机缸体和电池托盘。轻质铝合金在广泛的工作温度范围内具有良好的机械强度，使其成为动力系统应用的绝佳选择。然而，加工过程中残余应力的产生限制了人工智能的有效性。产生残余应力的根本原因是由于发动机缸体复杂的几何形状导致铸造过程中冷却速度的差异，以及缸体各部位的热膨胀失配。搅拌摩擦焊（FSW）部件的残余应力也使电池托盘的开发和生产变得非常复杂。残余应力可以通过固溶、退火和人工时效等热处理来降低。然而，有效处理技术的发展往往受到微观结构不一致、最终元素分析（FEA）中使用的参数不可靠（或不可验证）以及直接实验测量残余应力剖面的困难的阻碍。

With an effort to improve vehicle fuel efficiency, aluminum (Al) alloys are potential candidates for automotive powertrain components such as engine blocks and battery trays for electrical vehicles. Lightweight Al alloys have good mechanical strength at wide range of operating temperatures, making them excellent choices for powertrain applications. However, generation of residual stresses during processing limits Al's efficacy. The root cause of residual stress is the differences in cooling rate in casting of engine block due to its complex geometry, and thermal expansion mismatch in various parts of the block. Residual stress in friction-stir welded (FSW) components also significantly complicates development and production of battery trays. Residual stresses can be reduced by heat treatment such as solutionizing, annealing, and artificial ageing. The development of efficient treatment technologies, however, is often hindered by inconsistent microstructure, unreliable (or non-verifiable) parameters used in final element analysis (FEA), and difficulties in direct experimental measurements of residual stress profiles. This project will build upon a successful NSERC Engage-funded project between Nemak Canada and the applicant's UBC team in which stress, microstructures, phase analysis, and mechanical properties were investigated for prototypes of inline-6 engine blocks. The currently proposed project will focus on comprehensive studies on stress, microstructure evolution, and properties for a new-architecture I6 engine block and FSW battery tray. The new study involves stress scan using neutron diffraction, FEA, and its validation using the experimental data. In a fitness-for-service test, the prototype samples will be subjected to the real life load-temperature service conditions at our unique in-situ testing apparatus. The scope of studies includes I6 blocks and battery trays produced with varying casting, heat treatment, and welding parameters. Two HQP will be trained through this project. Nemak will incorporate the results into its operations, enabling production of I6 block in Ontario and leading to increase of supply orders to the Canadian aluminum industry.