Influence of Laser Beam Oscillation on Weld Geometry and Microstructure of AISI 304 Stainless Steel

Abstract Laser welding, thanks to the use of oscillating heads, is finding increasing use in modern industry. Laser oscillating welding heads offer numerous advantages over traditional laser welding heads. Currently, industries where preparing components for laser welding was previously a significant challenge can now adopt this welding technique thanks to the use of oscillation. The ability to improve the properties of welded joints, autogenous welding, and a high level of process automation make laser welding technology a promising industry. Unfortunately, the complexity of multidimensional processes, already difficult to apply, combined with the wide range of possibilities for modifying beam oscillation, requires a deeper understanding of the impact of new laser welding parameters on the quality of welded joints for industrial implementation. This article presents the results of studies on the microstructure of austenitic stainless steel welded with a laser beam at various welding beam oscillation parameters. The welds were obtained using a ytterbium QCW (Quasi Continuous Wave) fiber laser autogenous (without the use of the filler material). The test material was 4 mm thick AISI 304 austenitic stainless steel sheets as delivered. The aim of this study was to investigate the effect of oscillation parameters such as frequency, amplitude, and shape used during laser welding on weld geometry. Statistical relationships between the studied variables were identified. Laser power exhibits strong positive correlations with key weld geometry parameters, particularly penetration depth (H: r = 0.66), weld face width (B: r = 0.79), and cross-sectional area (S: r = 0.80). In contrast, laser beam oscillation parameters show a negative correlation with penetration depth (H: r = −0.48) and a moderate correlation with weld face width (B: r = 0.56). Other oscillation related effects demonstrate only weak correlations (r ≤ 0.38) with weld geometry. Mathematical models describing these relationships were developed and their quality verified. The presented models enable the prediction of the transverse shape dimensions of welds based on known welding parameter values.