Plastic deformation and forming behavior of high strength aluminum alloys for automotive applications

在汽车覆盖件中，低强度汽车铝合金的成形是比较常见的。然而，由于高强度铝合金的成形性较低，在制造汽车结构的成形应用中使用高强度铝合金一直是一个具有挑战性的问题。由于需要进一步减轻汽车的重量，以解决与汽车排放有关的环境问题，人们对这些合金重新产生了兴趣。需要对显微组织和成形性之间的关系有一个基本的了解，这对这些合金的开发和使用至关重要。这项拟议的研究计划旨在填补这一空白。 该研究计划对X615和AA7075两种高强度铝板材的材料微观结构进行了实验和计算模拟研究。这项研究将从颗粒和颗粒结构的角度表征这些合金的三维微观结构，在微观结构的尺度上进行力学测试，并建立微观结构与这些材料的塑性流动、成形性和断裂之间的关系。这项研究将利用能够量化微结构异质性附近的三维微结构和空间应变分布的实验技术。显微组织将由具有统计意义的参数来表示，并利用现代统计分析工具进行分析。此外，微结构成分的三维空间性质和本构特性将被纳入高级计算模型中，以系统地探讨微结构成分对由HSA片材制成的试件和部件的塑性流动、成形性、损伤和断裂行为的作用。基于有限元方法的计算模型将用于指导材料开发和HSA板材成形性能的预测。此外，计算模型将能够在参数研究中系统地评估单个微观结构参数对材料变形和损伤行为的作用。由于对微观结构的精确控制，这种研究的成本很高，而且很难在实验中进行。 该模型的研究将有助于更好地理解高强铝合金应变调节和局部化、损伤和破坏过程的微观力学。模拟研究的结果将加速现有的HSA和其他板材的进一步发展，以提供更好的成形性和使用寿命，并为汽车零件成形的材料选择提供明确的指导。

The forming of low strength automotive aluminum alloys is relatively common for automotive body panels. The use of high strength aluminum alloys in forming applications to create automotive structures, however, has been a challenging problem in the past due to their lower formability. There has been renewed interest in these alloys due to the need for further weight reduction of automobiles to address automotive emission related environmental concerns. A fundamental understanding of the relationship between microstructure and formability, critical to the development and use of these alloys, is needed. This proposed research program is intended to fill this gap. The proposed research program deals with experimental and computational modeling studies at the scale of material microstructure on two high strength aluminum (HSA) sheet alloys, X615 and AA7075. The proposed study will characterize the 3D microstructures of these alloys in terms of grain and particle structure, perform mechanical tests at the scale of the microstructure, and develop relationship between microstructure and plastic flow, formability, and fracture of these materials. This study will make use of experimental techniques that are capable of quantifying 3D microstructures and spatial strain distributions in the vicinity of microstructural heterogeneities. The microstructure will be represented by statistically significant parameters and analyzed by modern statistical analysis tools. In addition, 3D spatial nature and constitutive properties of microstructural constituents will be incorporated into advanced computational models to systematically explore the role of microstructure constituents on plastic flow, formability, damage, and fracture behavior of test specimens and components made from HSA sheet materials. The computational model based on the FE method will be used to guide material development and prediction of forming performance of HSA sheet materials. Additionally, the computational models will be able to systematically evaluate the role of individual microstructural parameters on material deformation and damage behaviour in a parametric study. Such studies are costly and difficult to carry out experimentally due to precise control of the microstructure. The modeling study will lead to a better understanding of micro-scale mechanics of strain accommodation and localization, damage, and failure processes in high strength aluminum alloys. The results of the modeling study will accelerate further development of existing HSA and other sheets to provide better formability and service life of lightweight automotive aluminum parts, as well as provide clear guidelines for material selection for automotive part forming.