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

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***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.