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<p>Additive manufacturing (AM) technologies, such as directed energy deposition (DED), offer unique advantages in fabricating complex metal structures;&#xa0;however they are often constrained by excessive heat accumulation due to the&#xa0;continuous high-energy input. Unlike previous studies that focused on thermal history qualitatively, this work introduces a quantitative residual temperature control strategy to experimentally and numerically replicate heat accumulation states. A series of DED experiments was conducted on 316L stainless steel under predefined initial temperatures, mimicking the heat accumulation states that occur in actual builds. Complementary computational fluid dynamics (CFD) simulations were employed to investigate the influence of residual temperature on the&#xa0;molten pool history, solidification parameters, microstructural evolution, and mechanical properties. The results demonstrate that increasing the residual temperature produces a larger, elongated molten pool, reduces cooling rates, and shifts the&#xa0;microstructure from fine columnar grains to coarse equiaxed structures. The results also&#xa0;show that increasing the residual temperature significantly alters the solidification conditions, causing the primary dendrite arm spacing (PDAS) to increase from 4.12 to 12.55&#xa0;μm. Consequently, this microstructural coarsening resulted in a substantial deterioration of mechanical properties, with microhardness and yield strength decreasing by 38.8 and 40.1%, respectively. These findings provide a novel, experimentally supported framework for understanding and managing heat accumulation in DED, offering valuable insights for process optimization and defect mitigation.</p>

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Simulating Heat Accumulation in Directed Energy Deposition through Residual Temperature Control: Numerical and Experimental Approaches

  • 期刊论文

  • 发表日期：

    2026年1月5日

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  • Lunwu Zhao,
  • Jianglong Wang,
  • Yu Kong,
  • Haihong Huang

摘要

Additive manufacturing (AM) technologies, such as directed energy deposition (DED), offer unique advantages in fabricating complex metal structures; however they are often constrained by excessive heat accumulation due to the continuous high-energy input. Unlike previous studies that focused on thermal history qualitatively, this work introduces a quantitative residual temperature control strategy to experimentally and numerically replicate heat accumulation states. A series of DED experiments was conducted on 316L stainless steel under predefined initial temperatures, mimicking the heat accumulation states that occur in actual builds. Complementary computational fluid dynamics (CFD) simulations were employed to investigate the influence of residual temperature on the molten pool history, solidification parameters, microstructural evolution, and mechanical properties. The results demonstrate that increasing the residual temperature produces a larger, elongated molten pool, reduces cooling rates, and shifts the microstructure from fine columnar grains to coarse equiaxed structures. The results also show that increasing the residual temperature significantly alters the solidification conditions, causing the primary dendrite arm spacing (PDAS) to increase from 4.12 to 12.55 μm. Consequently, this microstructural coarsening resulted in a substantial deterioration of mechanical properties, with microhardness and yield strength decreasing by 38.8 and 40.1%, respectively. These findings provide a novel, experimentally supported framework for understanding and managing heat accumulation in DED, offering valuable insights for process optimization and defect mitigation.