Hot Corrosion Behavior of Monel 400 and AISI 304 Dissimilar Weldments Exposed in the Molten Salt Environment Containing Na2SO4+60% V2O5 at 600 °C

This research work investigates the use of pulsed current for joining two dissimilar metals Monel 400 and AISI 304 using Pulsed Current Gas Tungsten Arc welding using three different filler metals such as ER309L, ERNiCu-7 and ERNiCrFe-3. Microstructure observations showed the presence of Partially Melted Zone (PMZ) at the heat affected zone (HAZ) of all the weldments. The formation of secondary phases was witnessed at the HAZ of Monel 400 on using ERNiCu-7 filler. Tensile studies corroborated that the bimetallic combinations employing ERNiCu-7 offer better tensile properties as compared to ER309L and ERNiCrFe-3 weldments. Parent metal Monel 400 exhibited better corrosion resistance as compared to other zones of the weldments when exposed in the synthetic molten salt environment containing Na-2 SO4 - 60% V2O5 environment at 600 degrees C. A detailed structure -property relationship was made using the combined techniques of optical microscopy and SEM. Also the hot corrosion products were revealed using the thermogravimetric plots, XRD and SEM/EDAX analysis.