Macrosegregation mechanisms in arc welds made with dissimilar filler metals

More often than not, filler metals differ from the workpiece in composition. To study macrosegregation in a single alloy system, alloy Cu–30Ni was arc welded with seven different filler metals, including Cu, Cu–12Ni, Cu–22Ni, Cu–30Ni, Cu–45Ni, Cu–67Ni and Ni. It was explained that liquid 1 flowing into liquid 2 of a different composition can cause macrosegregation if liquid 2 is below the liquidus temperature of liquid 1 to make liquid 1 freeze quickly. The liquidus temperatures of the base metal T LB and the bulk weld metal T LW were compared. All four mechanisms proposed recently by the authors were identified: mechanisms I ( T LW< T LB and quick freezing along pool boundary), II ( T LW> T LB and quick freezing along pool boundary), III ( T LW< T LB and quick freezing near pool bottom) and IV ( T LW> T LB and quick freezing near pool bottom).