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<p>Despite the growing use of plasma transferred arc (PTA) in directed energy deposition, the coupled multiphysics mechanisms governing the process, particularly in stationary configurations, remain poorly understood, limiting the ability to predict and optimize melt-pool formation and arc behavior. Existing studies have modeled these phenomena separately, thereby neglecting their strong coupling during transient melt-pool evolution. Furthermore, no prior study has examined PTA applied to AISI 1018 low-carbon steel in a stationary configuration. This study addresses that gap by developing a three-dimensional, transient, unified computational fluid dynamics (CFD) model that integrates the hydrodynamic, heat transfer, and electromagnetic equations. This unified framework describes electro-thermal energy conversion, electromagnetic effects, heat transfer, gas–liquid two-phase flow, and solid–liquid phase change in stationary PTA-based additive manufacturing. Interface tracking between the plasma arc and the molten substrate is captured using the Volume of Fluid method, and solid–liquid phase change is handled through an enthalpy-porosity method. At 110A, the transient temperature field, arc velocity, melt-pool geometry, electric potential, and current density distributions are predicted throughout the process. Results reveal that a high potential drop and current density near the electrode tip result in a peak arc temperature of approximately 22,000&#xa0;K and an axial jet velocity approaching 380&#xa0;m/s, a few millimeters downstream of the nozzle exit. A comparative study of laminar and turbulent (standard k–ε) flow regimes reveals that the turbulent model predicts approximately 7.3% higher net heat input to the substrate, resulting in earlier melt-pool initiation. Experiments are conducted using stationary PTA configuration on AISI 1018 low-carbon steel. Metallographic analysis reveals a well-defined fusion zone and graded heat-affected zones. The fusion zone geometry predicted by the numerical model generally agrees with metallographic measurements, with a normalized root-mean-square error of approximately 9%.</p>

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Computational Modeling of Plasma Transferred Arc–Substrate Heat Transfer in AISI 1018 for Additive Manufacturing

  • 期刊论文

  • 出版模式：

    开放获取

  • 发表日期：

    2026年7月31日

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  • Gaurab Neupane,
  • Ozan Ç. Özdemir,
  • Mohammad E. Taslim

摘要

Despite the growing use of plasma transferred arc (PTA) in directed energy deposition, the coupled multiphysics mechanisms governing the process, particularly in stationary configurations, remain poorly understood, limiting the ability to predict and optimize melt-pool formation and arc behavior. Existing studies have modeled these phenomena separately, thereby neglecting their strong coupling during transient melt-pool evolution. Furthermore, no prior study has examined PTA applied to AISI 1018 low-carbon steel in a stationary configuration. This study addresses that gap by developing a three-dimensional, transient, unified computational fluid dynamics (CFD) model that integrates the hydrodynamic, heat transfer, and electromagnetic equations. This unified framework describes electro-thermal energy conversion, electromagnetic effects, heat transfer, gas–liquid two-phase flow, and solid–liquid phase change in stationary PTA-based additive manufacturing. Interface tracking between the plasma arc and the molten substrate is captured using the Volume of Fluid method, and solid–liquid phase change is handled through an enthalpy-porosity method. At 110A, the transient temperature field, arc velocity, melt-pool geometry, electric potential, and current density distributions are predicted throughout the process. Results reveal that a high potential drop and current density near the electrode tip result in a peak arc temperature of approximately 22,000 K and an axial jet velocity approaching 380 m/s, a few millimeters downstream of the nozzle exit. A comparative study of laminar and turbulent (standard k–ε) flow regimes reveals that the turbulent model predicts approximately 7.3% higher net heat input to the substrate, resulting in earlier melt-pool initiation. Experiments are conducted using stationary PTA configuration on AISI 1018 low-carbon steel. Metallographic analysis reveals a well-defined fusion zone and graded heat-affected zones. The fusion zone geometry predicted by the numerical model generally agrees with metallographic measurements, with a normalized root-mean-square error of approximately 9%.