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

为了提高汽车的燃油效率，铝合金是汽车动力总成部件的潜在候选者，例如电动汽车的发动机机体和电池托盘。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，使其成为动力总成应用的极佳选择。然而，在加工过程中产生的残余应力限制了Al的有效性。产生残余应力的根本原因是由于发动机机体几何形状复杂，铸件冷却速度不同，以及机体各部位热膨胀失配。搅拌摩擦焊(FSW)组件中的残余应力也使电池托盘的开发和生产显著复杂化。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，有效处理技术的开发经常受到以下因素的阻碍：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)，以及残余应力分布的直接实验测量困难。该项目将建立在NSERC Engage资助的Nemak Canada和申请者的UBC团队之间的一个成功项目的基础上，在该项目中，对直列-6发动机机体的原型进行了应力、微观结构、相分析和机械性能的调查。目前提议的项目将集中于对新结构的I6发动机机体和FSW电池托盘的应力、微观组织演变和性能的综合研究。这项新的研究包括使用中子衍射进行应力扫描，有限元分析，以及使用实验数据进行验证。在服务适宜性测试中，样机样品将在我们独特的现场测试设备上接受真实的负载-温度服务条件。研究范围包括用不同的铸造、热处理和焊接参数生产的I6块和电池托盘。将通过该项目培训两名HQP。Nemak将把结果纳入其业务，使安大略省的I6区块能够生产，并导致加拿大铝业的供应订单增加。

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.