Effect of the addition of nickel powder and post weld heat treatment on the metallurgical and mechanical properties of the welded UNS S32304 duplex stainless steel

摘要

In this research, the effect of the addition of nickel powder and the application of audpost weld heat treatment (PWHT) on the welding properties of the UNS S32304 lean duplexudstainless steel were investigated in order to improve the microstructure and mechanicaludproperties. Nickel powder was directly poured inside the joint gap and mixed with the fillerudmetal during the Gas Tungsten Arc Welding (GTAW) process; moreover, the solution heatudtreatment was performed at 1100 °C for 10 min. The joints were characterized by opticaludmicroscopy (OM) and the evolution of the phase percentages in the different zones was studiedudby means of the image analysis technique. Tensile and hardness tests were carried out on theudjoints in order to evaluate the improvement of the mechanical properties. The results showedudthat both the addition of nickel powder during the welding process and the post weld heatudtreatment made it possible to improve the mechanical properties of the weld joints. PWHTudhad the best effect in restoring the equal percentage of ferrite and austenite compared toudthe addition of nickel powder.