Effects of shielding gas in joining SS304H sheets through laser welding process

In this work, an attempt was made to study the effects of various shielding gases on the quality of SS304H welded using a CO2 laser. The SS 304H sheets of 5 mm thickness were welded using three different shielding gases, viz. 100% CO2100% Argon and 80% Argon + 20% CO2 shielding gases at a flow rate of 15 liters/min. Weld quality was evaluated based on the analysis of mechanical properties, including hardness, tensile strength, and impact strength. The property variations are justified through metallurgical investigations, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD) analyses. Overall, the usage of 100% CO2 as shielding gas resulted optimum microstructural and mechanical characteristics with a hardness value of 280 HV and tensile strength of 729 MPa, though with a low impact toughness value of 33 J.