ABSTRACT
MANIKANDAN M.*, ARIVAZHAGAN N., and NAGESWARA RAO M.
School of Mechanical Engineering, VIT University, Vellore, India
*Corresponding author. E-mail: mano.manikandan@gmail.com
ABSTRACT
Superalloy C-276 is susceptible to hot cracking during gas tungsten arc welding (GTAW) technique. The occurring of microsegregation during solidification leads to the formation of P and µ phases. These phases have been accountable for the hot cracking. The chapter investigates the improvement of weldability of alloy C-276 by switching over from gas tungsten arc (GTA) to pulsed current gas tungsten arc (PCGTA) welding. Pulsed and continuous current GTAW was carried out both by autogenous mode and using different filler wires (ERNiCrMo-3 and ERNiCrMo-4). The weld joints were investigated on microstructure, microsegregation, and mechanical properties. The optical and scanning electron microscopy revealed that current pulsing improved the overall mechanical properties with refined microstructure in the fusion zone of all the weldments. Energy dispersive X-ray spectroscopy results bring out that joints fabricated by PCGTA autogenous and ERNiCrMo-4 shows reduced microsegregation compared to similar GTA weld joints. Joints fabricated by ERNiCrMo-3 indicate higher segregation with lower mechanical properties compared to other weldments. Bend test results in the absence of cracking irrespective of the type of welding are adopted in the current chapter.
