Shielding gas effects on flux cored arc welding of AISI 316L (N) austenitic stainless steel joints

Highlights: ► The effects of shielding gasses are analyzed. ► The impact strength increases with increasing of percentage of CO2 in shielding gas mixtures. ► The ferrite percentage decreases with increasing of percentage of CO2 in shielding gas mixtures. ► Microhardness values increases with increasing of ferrite percentage in the weld metal. -- Abstract: This paper deals with the flux cored arc welding (FCAW) of AISI 316L (N) austenitic stainless steel with 1.2 mm diameter of flux cored 316LT filler wire. The welding was carried out with different shielding gas mixtures like 100% Ar, 95% Ar + 05% CO2, 90% Ar + 10% CO2, 80% Ar + 20% CO2, 75% Ar + 23% CO2 + 2% O2 and 70% Ar + 25% CO2 + 5% O2 and 100% CO2. The main aim of the work is to study the effect of various shielding gas mixtures on mechanical properties and metallurgical characters. The microstructures and ferrite content of the welds were analyzed. The mechanical characteristics such as impact test, microhardness and ductility of welds were carried out. The fracture surface impact samples were analyzed through scanning electron microscope (SEM). The fracture surface revealed a ductile rupture at room temperature and ductile rupture with a few cleavages at lower temperatures occurred. The toughness and ferrite percentages of the welds were decreased for increase of the CO2 in shielding gas mixtures.