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

点击翻译按钮获取中文摘要

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.