Development of a Filler Metal for Weldments of a Ni-Cr-W Superalloy with High Creep Strength

Abstract

A series of weldability and creep tests of the weld metals were conducted to develop a filler metal with excellent weldability and high creep strength of the weldments of Ni-Cr-W superalloy. Contents of minor elements have a large effect on susceptibility to cracking in weldments. In particular, Zr, B, Y and Nb make the susceptibility to cracking high and addition of optimum contents of Ti or Mg reduce it slightly. A good correlation between values of the CSC (coefficient of susceptibility to cracking) of the filler metals and the weldability is recognized. On the basis of the knowledge, a filler metal with excellent weldability was developed for the Ni-18.5Cr-21W superalloy. The weld metal prepared using the developed wire possesses the creep rupture strength almost equal to that of the base metal which has a creep rupture strength above 9.8MPa for a 1×10⁵h life at 1000°C.