The Effect of Welding Heat Input on the Structure–Property Relationship of a New Grade Super Duplex Stainless Steel

Abstract

Herein, microstructural and mechanical characteristics and corrosion resistance of the UNS S32906 super duplex stainless steel (SDSS) welds are investigated. The gas tungsten arc welding technique is used with direct current electrode negative polarity. Welding is conducted in 1.19, 1.46, and 1.87 kJ mm−1 to evaluate the effect of heat input. The results show that the amount of ferrite phase decreases from 59.4% to 49.4% as the heat input increases. Moreover, only ferrite and austenite phases are observed in the microstructure without any other detrimental phases. Hardness test results show that the hardness of the weld metal rises up in comparison with that of the base metal. Furthermore, the more the heat input, the less the weldment hardness. The impact test shows that the toughness of the samples increases with heat input. Polarization tests show that base metal has a better corrosion behavior irrespective of the heat input of the weldments. With an increase in the heat input, the corrosion behavior is improved. It can be said that whether in terms of microstructure or mechanical properties or corrosion resistance, the specimens that are welded with the highest heat input show the best properties.