THE EFFECT OF SHIELDING GASES ON MECHANICAL PROPERTIES AND MICROSTRUCTURE OF AUSTENITIC STAINLESS

In this study AISI 304 L type of austenitic stainless steels were welded using 308 L consumable electrodes by the process of Gas Metal Arc Welding (GMAW). The aim of current study is to examine effects of shielding gas compositions on mechanical properties and microstructure of AISI 304 L weldments. A detailed study of gas metal arc welding of AISI 304 L stainless steel was carried out with different shielding gas compositions such as 100 % argon, 80 % argon + 20% CO2, 50 % Argon + 50 % argon and 100 % CO2. The mechanical properties were determined by performing different tests, viz. Charpy V notch impact test, tensile test, hardness test, bend test. Surface morphology had been analyzed by Scanning Electron Microscope (SEM). The results indicated that the shielding gas compositions have great influence on mechanical properties. Results revealed that increase in amount of CO2 in shielding gas resulted in higher tensile strength and hardness values than the base metal. The study also indicated that shielding gas composition also have an influence on toughness values which further depends upon -ferrite content in the weld metal. This -ferrite content decreases with increase in CO2 percentage of shielding gases. Decrease in -ferrite content has negative effects on toughness values of weldments. The gas metal arc welding is found to be suitable for welding of AISI 304 L austenitic stainless steels owing to their high welding speed and excellent mechanical properties