Study on the methods and mechanisms for suppressing porosity in narrow-gap oscillating laser wire-fill horizontal welding

To address the research gap regarding the control of pore defects in narrow-gap laser welded wire, this paper employs a combination of experimental analysis and finite element analysis to study the methods for suppressing pores and their related mechanisms in narrow-gap laser welded wire. The research results indicate that increasing oscillation frequency in circular mode suppresses porosity. With a constant fill cross-sectional area, suppression is effective only above a certain threshold frequency, which increases with fill cross-sectional area, the relationship as follows: 9 mm²–200 Hz; 10.5 mm²–250 Hz; 12 mm²–300 Hz; 13.5 mm²–350 Hz. Mechanistically, a higher oscillation frequency transforms the keyhole shape from conical to bowl-shaped, enhancing stability and reducing bubble formation. Additionally, porosity is avoided when the aspect ratio is below the control threshold of 1.13.