Macrosegregation in Cu–30Ni welds made with dissimilar filler metals

Abstract

To study macrosegregation in arc welds made with filler metals different (dissimilar) from the workpiece in composition, gas metal arc welding of alloy Cu–30Ni was conducted. With a pure Cu filler metal, a large filler rich zone was observed near the weld bottom with islands of partially mixed base metal scattered in the zone well within the fusion boundary. With a pure Ni filler metal, on the other hand, a large filler rich zone was again observed near the weld bottom but with filler rich intrusions penetrating into a thick continuous filler deficient beach along the fusion boundary. These results were explained based on two mechanisms proposed recently by the authors for macrosegregation near the bottoms of dissimilar filler welds, i.e. mechanism 3 for TLW<TLB and mechanism 4 for TLW>TLB, where TLW is the liquidus temperature of the weld metal and TLB that of the base metal.