Influence of the welding procedure on the ferrite content and fracture toughness of duplex stainless steel weldments

Different samples of a duplex stainless steel were welded using various shielding gases by GMAW with pulsed arc and synergic control. Ferrite content was calculated by different predictive methods and compared to the results of quantitative metallography. Schaeffler and Siewert et al diagrams seem to be the most accurate in the studied range of composition. Samples welded using argon as shielding gas possess the highest fracture toughness in the whole temperature range. However when argon 2% oxygen is used the measured fracture toughness values are the lowest ones. Fractographic analysis agree with this behaviour. (from authors' abstract)