Comparative analysis of the geometry and microstructure of laser-welded joints in different shielding atmospheres

Abstract

Laser welding is widely used in modern industry due to its high energy density, narrow heat-affected zone and the possibility of precise process control, which makes it particularly suit-able for applications where high accuracy and minimal deformations are required. Thanks to these characteristics, this procedure finds application in the automotive, railway, aviation and other branches of industry. One of the key process parameters that significantly affects welding stability, weld formation and the final quality of the welded joint is the type of pro-tective atmosphere. In this paper, a detailed comparative analysis of the geometry and mi-crostructure of laser-welded joints made in different protective atmospheres was performed: pure argon, pure helium and argon-helium mixture. Experimental tests were conducted with strictly controlled and constant laser welding parameters (laser power, welding speed, fo-cus), where the type of shielding gas was the only variable, in order to clearly isolate its in-fluence. The geometry of the weld was analyzed by measuring the width of the weld, the depth of penetration and the shape of the welded section, while the microstructural analysis was performed on the prepared metallographic samples using macroscopic and microscopic testing methods. Special attention is paid to the identification of possible discontinuities, porosity and changes in the structure of the metal. The test results indicate that the choice of shielding gas has a significant influence not only on the geometry of the weld, but also on the stability of the process, the formation of the melt and the character of the microstructure of the welded joint. The obtained results represent a reliable basis for the rational choice of the protective atmosphere with the aim of optimizing the quality of laser welded joints and improving the industrial application of this procedure.