Maintenance of the Austenite/Ferrite Ratio Balance in GTAW DSS Joints Through Process Parameters Optimization

The present work describes the influence of the parameters employed in the gas tungsten arc welding process (GTAW) when nickel powder is used as a filler metal in 2304/2507 duplex stainless-steel dissimilar joints. Multi-objective optimization was applied in order to maintain the austenite/ferrite percentage in the welded zone. A microstructural and phase quantification analysis was performed in each sample through optical and scanning electron microscopes. It was found that a nickel powder addition combined with low heat input increased the biphasic ratio across the different zones of the dissimilar welded samples. Although the austenite volume fraction increased in the 2304 heat-affected zone (HAZ) near to 25%, it was not sufficient according to international standards. The obtained results led to the maintenance of the 50/50 phase percentage in the 2507 HAZ welded joint side, as well as to the increment of the austenite percentage in the 2304 HAZ.