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<p>Laser powder bed fusion (LPBF) AlSi10Mg alloy exhibits high susceptibility to hydrogen porosity during fusion welding, and the mechanical properties of the welded joint are significantly reduced compared to the base metal (BM). In this study, LPBF AlSi10Mg alloy was welded using laser metal deposition (LMD) process, followed by direct aging (DA) heat treatment at 160&#xa0;°C for 6&#xa0;h. The porosity characteristics, microstructure, and mechanical properties of the welded joints were investigated, along with an in-depth analysis of the pore formation mechanism and the strengthening mechanism induced by DA heat treatment. The results show that the increase in the number of weld passes can significantly reduce both the hydrogen pore diameter and porosity in the weld metal (WM). The porosity concentration is notably higher at the inter-pass region. After DA heat treatment, the proportion of spherical and short rod-like Si phases in the WM increased, and the connectivity of eutectic Si networks also improved. Additionally, DA heat treatment reduces kernel average misorientation and geometric necessary dislocations, decreases low-angle grain boundaries proportion, and slightly increases grain size. Schmid factor analysis confirms reduced slip system activation, improving crack resistance via strengthening from nano-Si precipitates. DA heat treatment enhanced the average hardness of the welded joints, with the maximum average hardness reaching 111.04 HV. The tensile strength of the joint reached 293.6&#xa0;MPa, with an elongation of 1.7%. The enhancement of mechanical properties is attributed to the precipitation strengthening of silicon elements following DA heat treatment.</p> Graphical Abstract <p></p>

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Enhancing Mechanical Properties of LPBF-Fabricated AlSi10Mg Welded Joints via Laser Metal Deposition Combined with Direct Aging Heat Treatment

  • 期刊论文

  • 发表日期：

    2025年9月15日

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  • Zhaotong Li,
  • Li Cui,
  • Yingying Liu,
  • Fanhui Bu,
  • Zhenfu Shi,
  • Yingkai Shao,
  • Dingyong He,
  • Qing Cao

摘要

Laser powder bed fusion (LPBF) AlSi10Mg alloy exhibits high susceptibility to hydrogen porosity during fusion welding, and the mechanical properties of the welded joint are significantly reduced compared to the base metal (BM). In this study, LPBF AlSi10Mg alloy was welded using laser metal deposition (LMD) process, followed by direct aging (DA) heat treatment at 160 °C for 6 h. The porosity characteristics, microstructure, and mechanical properties of the welded joints were investigated, along with an in-depth analysis of the pore formation mechanism and the strengthening mechanism induced by DA heat treatment. The results show that the increase in the number of weld passes can significantly reduce both the hydrogen pore diameter and porosity in the weld metal (WM). The porosity concentration is notably higher at the inter-pass region. After DA heat treatment, the proportion of spherical and short rod-like Si phases in the WM increased, and the connectivity of eutectic Si networks also improved. Additionally, DA heat treatment reduces kernel average misorientation and geometric necessary dislocations, decreases low-angle grain boundaries proportion, and slightly increases grain size. Schmid factor analysis confirms reduced slip system activation, improving crack resistance via strengthening from nano-Si precipitates. DA heat treatment enhanced the average hardness of the welded joints, with the maximum average hardness reaching 111.04 HV. The tensile strength of the joint reached 293.6 MPa, with an elongation of 1.7%. The enhancement of mechanical properties is attributed to the precipitation strengthening of silicon elements following DA heat treatment.

Graphical Abstract