INFLUENCE OF SOLIDIFICATION KINETICS ON ALUMINUM WELD GRAIN-REFINEMENT

Aluminum alloy welds are often plagued by their susceptibility to hot tearing. The addition of titanium or zirconium is known to reduce the susceptibility through grain refinement. Previous models have suggested that these elements need merely to be contained as an alloy addition without concern for the form of the addition in the consumable prior to welding. The form of the titanium or zirconium addition was found to have a bearing on the effectiveness of the grain refinement addition. Results from this research revealed the intermetallic phase of the addition (TiAl3 or ZrAl3) must be present prior to welding to achieve the desired grain refinement. The solidification kinetics were also found to have a significant effect on the grain refinement achieved with the intermetallic additions.