A. Feghhi - Department of Materials Engineering, Najafabad Branch, Islamic Azad University, Isfahan, Iran.
A. Emamikhah - Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Isfahan, Iran.
Y. Bayat Asl - Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Isfahan, Iran.

The present study investigates the effects of type of shielding gas on the weld microstructure and mechanical properties of 409L ferritic stainless steel. For this purpose, Ar, Ar +20% He, Ar + 12% CO2, and Ar + 25% CO2 were used as shielding gases in gas metal arc welding (GMAW) of stainless steel. To evaluate the welds, non-destructive inspections of the specimens were followed by mechanical (hardness and tensile) tests while microstructural examinations of both the heat affected zone (HAZ) and the fusion zone were performed. Moreover, the phases produced were observed and identified by analyzing the specimens using SEM and EDS techniques. Results showed that specimens welded with Ar + 25% CO2 and Ar + 12% CO2 have the highest strength and hardness values in the fusion zone due to the formation of martensite around the ferrite grains. However, the enhancements observed in the mechanical properties of specimens welded with Ar and Ar +20% He were attributed to the reduced ferrite grain size and martensite content

Ferritic Stainless Steels, Shielding Gas, Gas Metal Arc Welding, Microstructure, Mechanical Tests