Numerical Simulation of TIG Welding Arc Based on ANSYS

Literature Overview

This study, published in 2009 by Zhu Jialei, Jiao Xiangdong, Yu Jianrong, Jiang Lipeng, Zhou Canfeng, and Xue Long from Beijing University of Chemical Technology, presents a numerical simulation of the TIG (Gas Tungsten Arc) welding arc using the ANSYS finite element analysis software. The research was supported by the Youth Scientific Research Fund of Beijing University of Chemical Technology (N07-18) and was conducted within the Beijing Key Laboratory of Opto-Electro-Mechanical Equipment Technology. The work addresses the fundamental challenge of understanding arc behavior, heat transfer mechanisms, and fluid dynamics within the welding process through computational methods, which is essential for optimizing TIG welding parameters in engineering applications.

Core Technical Content

The study focuses on modeling the TIG welding arc as a coupled electromagnetic-thermal-fluid problem. The numerical simulation captures the interaction between the electric current distribution in the arc, the resulting heat generation, and the convective heat transfer to the workpiece surface. The ANSYS platform is utilized to solve the governing equations for electric potential, temperature field, and velocity field simultaneously. The arc is typically modeled as a conical or cylindrical heat source with Gaussian or double-ellipsoidal distributions, and the boundary conditions account for convective and radiative heat losses from the workpiece surface.

Key Modeling Parameters

The numerical model considers the thermal conductivity, specific heat capacity, and density of the base material as temperature-dependent properties, which is critical for accurate prediction of the weld pool geometry and solidification behavior. The study demonstrates that the heat input distribution significantly influences the depth of penetration, width of fusion zone, and residual stress development in the weldment.

Engineering Practice Implications

From a cladding and bimetal pressure vessel fabrication perspective, the numerical simulation of TIG welding arcs provides invaluable insight for process optimization. In overlay welding applications, particularly for GTAW (Gas Tungsten Arc Welding) overlay of nickel-based alloys or stainless steels onto carbon steel substrates, understanding the thermal cycle is paramount to controlling dilution rates and ensuring metallurgical compatibility. The simulation results can be directly applied to predict the dilution percentage when overlaying materials such as Inconel 625 or Hastelloy C276 onto low-alloy steel substrates.

The study's methodology aligns with modern engineering practices where computational modeling supplements experimental validation. For bimetal pressure vessel fabrication under GB/T 150 or ASME VIII Div.1, the simulated thermal profiles can be used to assess the risk of hydrogen-induced cracking (HIC) and sulfide stress corrosion (SSC) in the heat-affected zone. Engineers can leverage such simulations to optimize preheat temperatures, interpass temperature limits, and post-weld heat treatment parameters before committing to costly full-scale fabrication.

Key Reflections and Study Insights

The 2009 publication represents an early application of finite element analysis to TIG welding arc modeling in Chinese academic research. While the computational capabilities of that era were limited compared to modern resources, the fundamental methodology remains highly relevant. The study establishes a framework that can be extended to more complex overlay welding scenarios, including multi-pass cladding with varying consumable compositions. The key insight is that numerical simulation serves as a powerful tool for pre-qualification of welding procedures, reducing the need for extensive trial-and-error experimentation while still satisfying the requirements of NB/T 47014 for welding procedure qualification.

The coupling of electromagnetic, thermal, and fluid fields in the simulation approach reflects the multi-physics nature of arc welding processes. For engineers working on bimetallic products, this coupled analysis is particularly important when dealing with dissimilar metal welds where thermal expansion mismatches can generate significant residual stresses. The study reinforces the importance of integrating computational tools into the welding procedure development workflow to achieve better quality control and cost efficiency in manufacturing.

Summary

This research contributes a valuable computational methodology for understanding TIG welding arc behavior, with direct applicability to overlay welding and bimetal pressure vessel fabrication. The ANSYS-based numerical simulation approach enables engineers to predict weld geometry, thermal cycles, and residual stress distributions prior to actual fabrication, thereby supporting informed decision-making in welding procedure qualification and process optimization. The study's enduring relevance lies in its demonstration that computational modeling, when properly validated against experimental data, can significantly enhance the predictability and quality of welding operations in demanding industrial applications.