INFLUENCE OF LASER WELDING PARAMETERS ON THE GEOMETRY OF WELDED JOINTS OF THIN-SHEET STAINLESS STEEL AISI 304

Abstract

Laser welding is one of the most promising methods of joining metals, combining high precision, minimal thermal deformation, and the possibility of process automatization. Due to the high energy density of the laser beam, the technology provides deep penetration with a narrow heat-affected zone, making it effective for welding corrosion-resistant austenitic steels, in particular AISI 304. At the same time, the peculiarities of thermal processes in laser welding, such as intense heating and rapid cooling of the metal, significantly affect the formation of the structure and properties of the welded joint, so the choice of optimal modes is crucial for preventing defects and ensuring high quality of the welded joint. The paper presents the results of an experimental and statistical study of the laser welding process of 1.5 mm thick AISI 304 steel using response surface methodology (RSM). The aim of the study was to determine the patterns of influence of the main parameters of laser welding on the formation of the geometry of the welded joint. Based on a factorial experiment, regression models were developed to describe the change in the area and width of the weld depending on changes in process parameters. Analysis of the results has shown that the main factors determining the geometry of the joint are the power of the laser radiation and the welding speed. Increasing the laser power contributes to an increase in the weld area, while increasing the speed reduces it. At high values of laser radiation power, the process becomes more stable, and the weld geometry becomes less sensitive to parameter changes. Laser beam defocusing has a negligible effect, only slightly increasing the width of the weld. The most pronounced interaction was found to be between power and speed, which tends to determine the maximum values of the weld area. The developed regression equations with a deviation of less than 10% confirmed the adequacy of the model and the effectiveness of using RSM to predict the geometry of the welded joint. The optimal welding modes identified in the study ensure the formation of high-quality, defect-free joints that defect-free joints and correspond to quality level “B” according to EN ISO 13919-1:2019.

Keywords: laser welding, thin-walled products, welding process optimization, response surface methodology, stainless steels, AISI 304.