Advanced Joining Technologies for Automotive Lightweight Structures: Friction Stir Welding (FSW)
Sponsored by: ACerS Manufacturing Division, TMS Aluminum Committee
Program Organizers: Yan Huang, Brunel University London; Carla Barbatti, Constellium; Yingchun Chen, Dura Automotive Systems
Wednesday 8:00 AM
October 12, 2022
Room: 328
Location: David L. Lawrence Convention Center
Session Chair: Yingchun Chen, Dura Automotive Systems ; Yan Huang, Brunel University London
8:00 AM Invited
3D Process Modeling of Linear Friction Welding Using a Smoothed Particle Hydrodynamics Based Approach: Srujan Rokkam1; Quang Truong1; Donald Weaver2; 1Advanced Cooling Technologies Inc; 2Air Force Research Laboratory
Linear friction welding (LFW) is a solid-state joining process in which a weld between two metals is formed by combined action of frictional heating and forming force that creates a weld interface. Due to large deformation, commercially available software tools are limited to modeling of LFW in 2D using Finite Element Method (FEM) with adaptive mesh controls. In this work, we developed a meshless approach that utilizes a combination of Smoothed Particle Hydrodynamics (SPH) and FEM to obtain a physics-based model capable of capturing the thermo-mechanical behavior LFW process in 3D. The developed model is employed to simulate and investigate flash formation and burn-off distance in surrogate welds. The simulation results agreed well with FE simulation and experimental data. This work was funded by an U.S. Air Force Phase II SBIR program, Contract FA8650-19-C-5050, awarded to ACT Inc.
8:30 AM Invited
Microstructural and Mechanical Property Change during Friction Element Welding: Ankit Varma1; Laine Mears1; Hongseok Choi1; Xin Zhao1; 1Clemson University
To realize the full potential of lightweight materials with high strength-to-weight ratios in improving a vehicle’s fuel economy, it is critical to develop techniques that can efficiently weld dissimilar materials. Friction element welding (FEW) has been proposed for welding highly dissimilar materials with different strengths and thicknesses. The temperature/stress evolution during the process, as well as the microstructural and mechanical property changes following welding, are, however, poorly understood. A fully coupled thermal-mechanical finite element model is developed to simulate the FEW process and predict the temperature and stress evolution during FEW. The correlation between microstructural alteration and microhardness improvement by FEW is investigated experimentally. The effects of temperature and stress on microstructural transformation are unveiled. Their influence on the transverse shear strength of the welded specimen is also elucidated.
9:00 AM
Additive Friction Stir Deposition for Cladding and Repair of Lightweight Aluminum: Greg Hahn1; Hang Yu1; 1Virginia Polytechnic Institute and State University
Additive friction stir deposition is a novel solid-state metal additive manufacturing process that enables the cladding and repair of lightweight aluminum structures with low energy, low cost, and low residual stresses. Based on repaid plastic deformation at elevated temperatures, the deposited material and base material are co-plastically deformed and mixed, resulting in strong bonding with a gradient interface. In this presentation, we show examples of dissimilar material cladding on 6xxx aluminum automotive sheet metals as well as structural repair of high strength 7xxx aluminum. Excellent post-cladding and post-repair mechanical performance are achieved, in which good interface quality plays a key role. We also explore the effects of thermo-mechanical processing on the temper and microstructure of the base material, which helps us advance our modeling efforts to better predict the static and fatigue performance of the resulting aluminum structures.
9:20 AM
Friction Stir Lap Welding of 3T Al Sheets in a Robotic Platform: Piyush Upadhyay1; Hrishikesh Das1; Shivakant Shukla1; 1Pacific Northwest National Laboratory
Replacing the steel passenger cage with an appropriately designed stamped Al assembly within the existing steel body construction is a viable approach toward automotive light-weighting. A cost-effective joining method that can meet and exceed the crash requirement for three sheet joint configuration is needed for this goal. PNNL has been developing three sheet dissimilar Al joints using Friction stir welding in coupon and near-component level. Process developments were first done on a stiff Gantry machine and efforts are underway to transfer the process to a robotic platform. Thus far, viable three sheet FSLW joints have been demonstrated up to a welding speed of 1m/min in FSW robot in linear and curved welding paths. Lap shear, T peel, U peel tests, and joint characterization will be presented. Challenges associated with robot FSW and solution approaches will also be discussed.
9:40 AM
Microstructure and Properties of Mg/Mg and Mg/Al FSW Welds: Krzysztof Mroczka1; Stanislaw Dymek2; Adam Pietras3; Aleksandra Węglowska3; Carter Hamilton4; Mateusz Kopyściański2; 1Cracow University of Technology; 2AGH University of Science and Technology in Krakow; 3The Łukasiewicz Research Network Institute of Welding; 4Miami University
Similar welds of cast AZ91 magnesium and dissimilar welds of cast AZ91 with wrought 6082 aluminum were fabricated by FSW. The unique microstructures of the welds were characterized through light and electron microscopies. A new approach to tensile testing of the welds was applied - micro specimens excised from the specific areas of the weld. The micro samples were precisely excised by wire EDM, and the cross-section of each specimen was 0.7 x 0.7 mm. Conventional tensile tests were also performed on macro samples containing the entire weld. Afterward, fracture surfaces were examined by SEM, and micro-hardness tests revealed the hardness distribution across the weld cross-sections. To complement the microstructural characterization, numerical simulations of the welding process provided deeper insight into the material flow during mixing and to the temperature distributions across the weld zones. The research was carried out as part of a project financed by the Polish government.