Numerical Investigation of Arc-Keyhole Interaction in K-TIG Welding

Researchers at the South China University of Technology have conducted a study on the interaction between arc plasma and keyhole in deep-penetration K-TIG welding, focusing on the effects of metal vapour on arc plasma characteristics. The research, funded by the National Key Research & Development Program of China and the 2023 Shenzhen High-tech Zone Longhua Park Innovation Platform Construction Project, utilized a fully coupled arc plasma-keyhole-weld pool model to simulate the process and investigate the transport mechanisms governing arc-keyhole interaction.

Key Takeaways:

• The presence of metal vapour was found to increase electrical conductivity within the medium-temperature range, altering current density distribution and reducing Joule heating and radiation losses.
• The maximum arc plasma temperature decreased from approximately 19,500 K to about 14,500 K with metal vapour, causing the low-temperature isotherms near the tungsten electrode tip to expand outward and the high-temperature core region to contract inward.
• The arc plasma penetrated further into the keyhole with increasing keyhole depth, but the presence of metal vapour reduced the potential difference by about 2.0 V and decreased the axial velocity of the arc plasma by roughly 200 m/s after keyhole formation.
• The research concluded that comparisons between simulated and experimentally captured arc plasma profiles at representative keyhole depths exhibited high consistency, confirming the accuracy and reliability of the proposed simulation approach.
• The study was peer-reviewed and published in the Journal of Manufacturing Processes, with additional information available from Yonghua Shi at the South China University of Technology.

Statistics:

• Maximum arc plasma temperature decreased by approximately 5,000 K with metal vapour.
• Potential difference reduced by about 2.0 V with metal vapour.
• Axial velocity of the arc plasma decreased by roughly 200 m/s after keyhole formation with metal vapour.
• Electromagnetic force reduced by approximately 30 Pa with metal vapour.
• Arc plasma pressure decreased from approximately 1700 Pa to about 1400 Pa with metal vapour.

Sources:

• Numerical Investigation of the Transport Mechanisms Governing Arc-Keyhole Interaction In Deep-penetration K-tig Welding Under the Influence of Metal Vapour. Journal of Manufacturing Processes, 2025;152:929-963. (Elsevier Sci Ltd, 125 London Wall, London, England)
• National Key Research & Development Program of China
• The 2023 Shenzhen High-tech Zone Longhua Park Innovation Platform Construction Project
• Guangxi Science and Technology Plan Project