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<p>A three-dimensional (3D) transient heat transfer model based on conduction was established to examine the temperature dispersal during hybrid narrow-gap welding at three distinct pulse frequencies: 180, 55, and 30 Hz. The welding order began with a cold-metal-transfer root pass, followed by pulsed gas-metal arc welding for the filling and capping passes. To capture the unique thermal behaviour of the cold-metal-transfer process, the model accounted for heat transfer during both the arcing and short-circuiting phases. Spiral arc oscillation was applied for the root pass, and triangular oscillation for subsequent passes. The simulated cooling rates showed strong agreement with experimental measurements, validating the model. Among the weld passes and zones, the root pass and heat-affected zone showed the highest cooling rates (&gt; 350 K/s). The 180 Hz condition resulted in the slowest cooling, whereas 30 Hz led to rapid cooling, especially in the later passes. At 30 Hz, a higher volume fraction of acicular ferrite (86.80%) was obtained, correlating with improved tensile performance. However, repeated thermal cycling led to ferrite coarsening and a reduction in hardness. The 30 Hz condition yielded superior mechanical properties (YS: 474.0 MPa, UTS: 596.0 MPa), highlighting the significance of pulse frequency on weld quality.</p>

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Heat transfer dynamics in narrow gap joints with hybrid CMT-P-GMA welding: a 3D finite element study

  • 期刊论文

  • 发表日期：

    2026年2月11日

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  • Polamuri Sudheer Kumar,
  • Chitral Srihari,
  • Nasina Venkaiah,
  • Degala Venkata Kiran,
  • Virendra Pratap Singh

摘要

A three-dimensional (3D) transient heat transfer model based on conduction was established to examine the temperature dispersal during hybrid narrow-gap welding at three distinct pulse frequencies: 180, 55, and 30 Hz. The welding order began with a cold-metal-transfer root pass, followed by pulsed gas-metal arc welding for the filling and capping passes. To capture the unique thermal behaviour of the cold-metal-transfer process, the model accounted for heat transfer during both the arcing and short-circuiting phases. Spiral arc oscillation was applied for the root pass, and triangular oscillation for subsequent passes. The simulated cooling rates showed strong agreement with experimental measurements, validating the model. Among the weld passes and zones, the root pass and heat-affected zone showed the highest cooling rates (> 350 K/s). The 180 Hz condition resulted in the slowest cooling, whereas 30 Hz led to rapid cooling, especially in the later passes. At 30 Hz, a higher volume fraction of acicular ferrite (86.80%) was obtained, correlating with improved tensile performance. However, repeated thermal cycling led to ferrite coarsening and a reduction in hardness. The 30 Hz condition yielded superior mechanical properties (YS: 474.0 MPa, UTS: 596.0 MPa), highlighting the significance of pulse frequency on weld quality.