THE EFFECT OF SHI ELDI NG GASES ON MECHANI CAL PROPERTI ES AND MI CROSTRUCTURE OF AUSTENI TI C STAI NLESS STEEL W ELDMENTS

In this study, AISI 304 L type austenitic stainless steels were welded using 308 L consumable electrodes employing the Gas Metal Arc Welding (GMAW) process. The objective was to investigate the effects of various shielding gas compositions on the mechanical properties and microstructure of AISI 304 L weldments. A comprehensive analysis was conducted using different shielding gas mixtures such as 100% argon, 80% argon + 20% CO2, 50% argon + 50% CO2, and 100% CO2, with mechanical properties assessed through Charpy V notch impact tests, tensile tests, hardness tests, and bend tests. Scanning Electron Microscope (SEM) analysis was used to study surface morphology. The results demonstrated a significant impact of shielding gas compositions on the mechanical properties of weldments, revealing that an increase in CO2 content resulted in enhanced tensile strength and hardness compared to the base metal. However, the investigation also showed that higher CO2 percentages negatively affected toughness values, linked to decreases in δ-ferrite content within the weld metal. Overall, GMAW was found to be effective for welding AISI 304 L stainless steels, characterized by high welding speed and favorable mechanical properties.