The effect of post-weld heat treatment on microstructure and tensile properties of alloy C-276 welded joints fabricated by pulsed current gas tungsten arc welding

The Mo-rich TCP phases P and μ are susceptible to hot cracking in the alloy C-276. These phases can be reduced by quashing the microsegregation of alloying element Mo in the weldment. The present study investigates the possibility of reducing the microsegregation by post weld heat treatment of the weldments. The joints were fabricated by pulsed current gas tungsten arc welding by employing different filler wires ERNiCrMo-3 and ERNiCrMo-4. The weld joints were characterized with respect to microstructure, Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and tensile test. The optical microstructure revealed the fine equiaxed dendrites were observed in the fusion zone. EDS analysis revealed the presence of Mo-rich segregation in the subgrain boundary in the ERNiCrMo-3 and absence in the later. The results show that selection of temperature to dissolve Mo segregation is not sufficient in the case of ERNiCrMo-3. The tensile result shows the improved strength in both weldments compared to base metal.