Influence of GTAW shielding gas on the microstructure of duplex stainless steel-welded joints

This work aims to describe the influence of the variation of the nitrogen in the shielding gas of the Gas Tungsten Arc Welding process (GTAW), on the microstructural evolution, mechanical performance, and the variation of the phase percentage in the heat-affected zone (HAZ) and weld metal (WM), of the duplex stainless steel (DSS) 2205. The results reveal the several types of austenite phase morphologies in WM and HAZ, regardless of the addition or increase of nitrogen. However, proportion of this phase throughout the analysis of phase percentage indicates that the austenite reaches 67% in the WM and 37% in the HAZ when using a nitrogen-enriched atmosphere (50% Ar–50% N₂). In addition, microhardness results indicate that although the variation in nitrogen content does not influence this property, both the WM and HAZ exhibit increased values compared to the base metal. However, this behavior is related to the microstructural development of the weld.