The characteristics of dynamic stability in aluminium alloy keyhole weld pool flow

Abstract

The keyhole welding process in Variable Polarity Plasma Arc Welding enhances weld quality significantly, yet it introduces pool instability. Dynamic stability is pursued by investigating molten metal flowing within keyholes and their characteristics. Weld pool flow patterns are obtained via particle tracking, while instability characteristics are captured employing a high-speed camera. Analysing directional molten metal flow unveils Convergence and Separation Points in weld pool flow. The latter’s displacement induces weld pool instability, resulting in an increase in keyhole area and a reduction in the pinch angle. The keyhole area signifies pool instability, while the rear wall angle reflects the welding state. These findings provide a theoretical basis for weld control and advance vision-based intelligent manufacturing welding techniques.

KEYWORDS:

• Keyhole welding
• Molten metal
• Flow mechanism
• Fluid flow
• Characteristic extraction
• Destabilisation
• Aluminium alloy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (grant numbers U1937207, 52005014 and 52275302), the Major Science and Technology Innovation Project of Shandong Province (grant number 2020JMRH0504), Jinan Innovation Team Project (grant number 2021GXRC066) and Quan Cheng Scholars Construction Project (grant number D03032), State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology (grant number AWJ-21M24). It was also supported by the China Scholarship Council for one year study at Osaka University (grant number 202206540024).