Investigation of keyhole behaviour and its impact on the performance of laser beam oscillating welding through imaging and acoustic signal analysis

Abstract

As an emerging laser welding optimisation technique, beam oscillation still lacks detailed investigation into its underlying process mechanisms. This study investigates the microstructure and mechanical properties of 316LN welded joints under four oscillation modes, the results demonstrate that beam oscillation can suppress columnar grain growth and reduce porosity defects, thereby enhancing weld formation and mechanical properties. Building upon these findings, visual and acoustic sensing techniques are employed to analyse dynamic features of keyholes and energy distribution. The correlation between keyhole geometric features and porosity propensity across different oscillation modes is elucidated through visual information. Additionally, the time and frequency domain features of the acoustic signals effectively characterise the stability of the welding process and laser energy absorption efficiency.

KEYWORDS:

• Laser beam oscillation welding
• 316LN stainless steel
• process monitoring
• mechanical properties
• microphone
• acoustic emission
• laser keyhole

Disclosure statement

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

Additional information

Funding

This research is financially supported by the National Natural Science Foundation of China [grant No. 52175309], and the National Key Research and Development Program of China [grant No. 2018YFB1107900].