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<p>This study investigates the thermomechanical and microstructural evolution in dissimilar thin aluminium alloy sheets, AA6061 and AA5182-H34, joined using Friction Stir Welding (FSW), widely adopted in the automotive and aerospace industries for high-strength, lightweight structural applications. Blanks produced via FSW face challenges in joint strength and residual stress development, primarily influenced by peak temperatures generated through frictional heating during the process. A three-dimensional coupled thermo-mechanical finite element model was developed to simulate the FSW process. Experimental validation was achieved using embedded thermocouples and strain rosettes placed strategically along the weld path. Simulation results confirmed successful solid-state bonding, with thermal cycles remaining below the melting points of both alloys. The peak von Mises stress and equivalent plastic strain (PEEQ) occurred near the tool shoulder and advancing side, indicating zones of strain localization and mechanical vulnerability. Longitudinal residual stresses exhibited a distinct M-shaped asymmetric distribution, with peak tensile values reaching 39.21&#xa0;MPa on the advancing side, while the retreating side showed comparatively lower tensile stresses (36.66&#xa0;MPa). Transverse residual stresses were significantly lower (~ 70%) and therefore considered secondary in structural assessment. Furthermore, micro-residual stress analysis was performed in conjunction with electron backscatter diffraction (EBSD) metrics. Kernel Average Misorientation (KAM) maps revealed plastic deformation gradients within the nugget zone and thermo-mechanically affected zone (TMAZ), further validating the simulated and experimentally assessed macro residual stress and PEEQ predictions. Dislocation density estimations, derived from KAM values, indicated elevated densities in the weld nugget, confirming residual lattice strain accumulation consistent with differential thermal contraction. The integration of finite element modelling with macro and microscopic residual stress indicators provides a holistic understanding of weld performance. The results contribute to optimized process parameter design and enhance predictive capabilities for fatigue resistance, dimensional stability, and overall joint reliability in thin-sheet dissimilar FSW applications.</p>

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Analysis of Temperature and Residual Stress Distribution in Friction Stir Welded Tailored Blank of Dissimilar Aluminium Alloy: Insights from Numerical Simulation and Experimental Observations

  • 期刊论文

  • 发表日期：

    2025年6月13日

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  • P. Shrivastava,
  • S. Chavhan

摘要

This study investigates the thermomechanical and microstructural evolution in dissimilar thin aluminium alloy sheets, AA6061 and AA5182-H34, joined using Friction Stir Welding (FSW), widely adopted in the automotive and aerospace industries for high-strength, lightweight structural applications. Blanks produced via FSW face challenges in joint strength and residual stress development, primarily influenced by peak temperatures generated through frictional heating during the process. A three-dimensional coupled thermo-mechanical finite element model was developed to simulate the FSW process. Experimental validation was achieved using embedded thermocouples and strain rosettes placed strategically along the weld path. Simulation results confirmed successful solid-state bonding, with thermal cycles remaining below the melting points of both alloys. The peak von Mises stress and equivalent plastic strain (PEEQ) occurred near the tool shoulder and advancing side, indicating zones of strain localization and mechanical vulnerability. Longitudinal residual stresses exhibited a distinct M-shaped asymmetric distribution, with peak tensile values reaching 39.21 MPa on the advancing side, while the retreating side showed comparatively lower tensile stresses (36.66 MPa). Transverse residual stresses were significantly lower (~ 70%) and therefore considered secondary in structural assessment. Furthermore, micro-residual stress analysis was performed in conjunction with electron backscatter diffraction (EBSD) metrics. Kernel Average Misorientation (KAM) maps revealed plastic deformation gradients within the nugget zone and thermo-mechanically affected zone (TMAZ), further validating the simulated and experimentally assessed macro residual stress and PEEQ predictions. Dislocation density estimations, derived from KAM values, indicated elevated densities in the weld nugget, confirming residual lattice strain accumulation consistent with differential thermal contraction. The integration of finite element modelling with macro and microscopic residual stress indicators provides a holistic understanding of weld performance. The results contribute to optimized process parameter design and enhance predictive capabilities for fatigue resistance, dimensional stability, and overall joint reliability in thin-sheet dissimilar FSW applications.