Publication

Abstract : The practice of Ni-based superalloy 686 has been diversified because of its superior capability to preserve corrosion resistance at high temperature and antagonistic environments. The premature failure due to hot cracking and their mitigation is a challengeable task in welding of superalloy 686. Microsegregation occurs during solidification is largely responsible for the observed hot cracking. The segregation of alloying elements lay down a path to the formation of topologically close-packed (TCP) phases (σ, P & μ) at the end of solidification in the fusion zone. The inkling to prevent the hot cracking is to deduce the microsegregation of alloying elements during solidification. The economical way to reduce the extent of microsegregation is to introduce the current pulsing technique in the conventional Gas Tungsten Arc Welding (GTAW) process, and this can be rectified by proper selection of welding consumable. This method efficiently minimizes the microsegregation and also offers finer weld microstructure with improved mechanical properties. The weldments produced with pulsed current Gas Tungsten Arc Welding (PCGTAW) were evidenced to be highlyresistance against corrosion in synthetic sea water environment corrosion test. This chapter aims to elaborate on these issues.