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<p>Laser powder bed fusion (L-PBF) processed AlSi10Mg shows varied microstructural features, including columnar and equiaxed grains, heat-affected zones (HAZs), and porosity. These features have a significant impact on local deformation and the overall mechanical response. To measure these effects, a microstructure-based crystal plasticity finite element model (CPFEM) was developed. The model accurately predicts tensile behaviour, yielding a 0.45% offset yield strength of 274&#xa0;MPa and an ultimate tensile strength (UTS) of 420–434&#xa0;MPa, which closely matches experimental results (yield strength of 280&#xa0;MPa and UTS of 418–437&#xa0;MPa). The difference between the simulation and experiment remains within 3–8&#xa0;MPa (RMSE ≈ 5–7&#xa0;MPa, R<sup>2</sup> ≈ 0.992–0.997). Local stress analysis reveals that grain orientation has a significant impact on slip activation. Grains with higher Schmid factors deform more uniformly, while grains with low Schmid factors exhibit 15–25% more strain localization due to limited slip accommodation. Columnar grains aligned with the loading direction show a more uniform stress distribution and slightly higher UTS (~ 433&#xa0;MPa) compared to grains that are perpendicular (~ 431&#xa0;MPa). In HAZ regions, grains oriented perpendicular to the load have a yield strength approximately 7&#xa0;MPa lower and a UTS approximately 20&#xa0;MPa lower, attributed to transitions from coarse to fine grains and localised boundary stresses. The presence of pores raises local von Mises stresses by 35–40% and lowers UTS from 420&#xa0;MPa (with no pores) to 413&#xa0;MPa (with multiple pores). These stress hotspots correspond with increased shear strain around pore surfaces, consistent with experimental fractography that shows void coalescence, Si-network decohesion, and microcrack initiation at α-Al/Si interfaces. Overall, this study demonstrates how the CPFEM framework can directly identify the effects of microstructure, orientation, and defect shape on stress localisation and the variation in tensile response in L-PBF AlSi10Mg.</p>

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Microstructural analysis and deformation mechanisms in additively manufactured AlSi10Mg alloy: a crystal plasticity finite element study

  • 期刊论文

  • 发表日期：

    2026年2月12日

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  • Bibhu Kalyan Panda,
  • Thati Puneeth,
  • Seshadev Sahoo,
  • Ashish Kumar Nath

摘要

Laser powder bed fusion (L-PBF) processed AlSi10Mg shows varied microstructural features, including columnar and equiaxed grains, heat-affected zones (HAZs), and porosity. These features have a significant impact on local deformation and the overall mechanical response. To measure these effects, a microstructure-based crystal plasticity finite element model (CPFEM) was developed. The model accurately predicts tensile behaviour, yielding a 0.45% offset yield strength of 274 MPa and an ultimate tensile strength (UTS) of 420–434 MPa, which closely matches experimental results (yield strength of 280 MPa and UTS of 418–437 MPa). The difference between the simulation and experiment remains within 3–8 MPa (RMSE ≈ 5–7 MPa, R2 ≈ 0.992–0.997). Local stress analysis reveals that grain orientation has a significant impact on slip activation. Grains with higher Schmid factors deform more uniformly, while grains with low Schmid factors exhibit 15–25% more strain localization due to limited slip accommodation. Columnar grains aligned with the loading direction show a more uniform stress distribution and slightly higher UTS (~ 433 MPa) compared to grains that are perpendicular (~ 431 MPa). In HAZ regions, grains oriented perpendicular to the load have a yield strength approximately 7 MPa lower and a UTS approximately 20 MPa lower, attributed to transitions from coarse to fine grains and localised boundary stresses. The presence of pores raises local von Mises stresses by 35–40% and lowers UTS from 420 MPa (with no pores) to 413 MPa (with multiple pores). These stress hotspots correspond with increased shear strain around pore surfaces, consistent with experimental fractography that shows void coalescence, Si-network decohesion, and microcrack initiation at α-Al/Si interfaces. Overall, this study demonstrates how the CPFEM framework can directly identify the effects of microstructure, orientation, and defect shape on stress localisation and the variation in tensile response in L-PBF AlSi10Mg.