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<p>This study investigates the effectiveness of a novel hybrid heat source model (combining conical and double-ellipsoid heat source models) in simulating the TIG welding process (bead on plate) of novel Rheocast Al–15Mg<sub>2</sub>Si–4.5Si composite. The developed finite element model, which adopts a novel approach of employing the generalized model parameters estimated from experimental measurements, is found to be effective in simulating the bead geometry and melt pool temperature with reasonable accuracy for different welding parameters. The weld zone of the bead-on-plate welded sample shows the evidence of melting and renucleation of primary Al, and primary as well as eutectic Mg<sub>2</sub>Si phases. However, the presence of primary Mg<sub>2</sub>Si particles is found to be minimal in the weld/bead zone due to insufficient heat generated in the welding process to melt the high melting (1085&#xa0;°C) Mg<sub>2</sub>Si particles. Moreover, noticeable decrease in grain size and enhancement in sphericity values of both the primary grains (Mg<sub>2</sub>Si and α-Al) has been recorded in the weld zone compared to that of starting rheocast composite, due to rapid cooling associated with the TIG welding process. Following TIG welding, heat treatment significantly enhances the microstructural homogeneity and mechanical performance of the weld zone, due to the emergence of spheroidal eutectic Mg<sub>2</sub>Si and Si particles, reduced microsegregation, and refined primary grains. The X-ray diffraction analysis reveals a reduction in the α-Al volume fraction of the composite in the post-heat-treated state, attributed to the enhanced formation of eutectic Mg<sub>2</sub>Si from the supersaturated α-Al solid solution, which in turn increases bulk hardness values of the weld zone. Furthermore, tensile results as well as fracture surface morphology of the weld zone also establishes the essence of post-weld heat treatment, as evident from enhanced tensile properties of the weld zone, shifting the fracture morphology from quasi-cleavage to mixed mode one.</p>

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Finite Element Modeling of Weld Bead Geometry and Experimental Studies on Microstructure and Mechanical Properties of Fusion Welded Novel Rheocast Al–15Mg2Si–4.5Si Composite

  • 期刊论文

  • 发表日期：

    2026年1月12日

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  • Bappa Das,
  • Sambit Kumar Sahoo,
  • Soumojit Dasgupta,
  • Santanu Das,
  • Prosenjit Das

摘要

This study investigates the effectiveness of a novel hybrid heat source model (combining conical and double-ellipsoid heat source models) in simulating the TIG welding process (bead on plate) of novel Rheocast Al–15Mg2Si–4.5Si composite. The developed finite element model, which adopts a novel approach of employing the generalized model parameters estimated from experimental measurements, is found to be effective in simulating the bead geometry and melt pool temperature with reasonable accuracy for different welding parameters. The weld zone of the bead-on-plate welded sample shows the evidence of melting and renucleation of primary Al, and primary as well as eutectic Mg2Si phases. However, the presence of primary Mg2Si particles is found to be minimal in the weld/bead zone due to insufficient heat generated in the welding process to melt the high melting (1085 °C) Mg2Si particles. Moreover, noticeable decrease in grain size and enhancement in sphericity values of both the primary grains (Mg2Si and α-Al) has been recorded in the weld zone compared to that of starting rheocast composite, due to rapid cooling associated with the TIG welding process. Following TIG welding, heat treatment significantly enhances the microstructural homogeneity and mechanical performance of the weld zone, due to the emergence of spheroidal eutectic Mg2Si and Si particles, reduced microsegregation, and refined primary grains. The X-ray diffraction analysis reveals a reduction in the α-Al volume fraction of the composite in the post-heat-treated state, attributed to the enhanced formation of eutectic Mg2Si from the supersaturated α-Al solid solution, which in turn increases bulk hardness values of the weld zone. Furthermore, tensile results as well as fracture surface morphology of the weld zone also establishes the essence of post-weld heat treatment, as evident from enhanced tensile properties of the weld zone, shifting the fracture morphology from quasi-cleavage to mixed mode one.