Effects of W and Ce micro addition in filler metal on microstructure and creep strength of Cr35Ni45NbM alloy weld joint

Abstract The effect of the filler metal chemical composition on the performance of Cr35Ni45NbM alloy weld joint is studied in this paper. The Cr35Ni45NbM alloy weld joints with two type filler metals are produced through manual gas tungsten arc welding (GTAW) process. The number of carbide in weld metal is more than that of base metal, and the size of carbide is smaller. The carbide size in the fusion zone of the weld joint with addition Ce and W elements in filler metal is smaller than that without Ce and W elements. The micro addition of W and Ce in filler metal could improve the high temperature creep strength of weld joint, and has no evident effect on the tensile properties at room temperature. After high temperature creep test, the creep test specimens break at fusion zone, which indicates that the weak part of the weld joint is the fusion zone during service. In the creep process, the cracks first nucleate at the interface between carbide and γ matrix, and then propagate along the carbide, finally the weld joint fractures along the dendrite boundary.