Applying Solidification Theory to Aluminum Weldability and Consumable Development

Abstract

One defect encountered in the fusion zone when welding aluminum alloys involves solidification cracking (i.e., the tearing apart of grain boundary liquid films at the trailing edge of the weld pool). This problem can often be mitigated by the proper selection of filler metal. Two key engineering examples, one aerospace and one maritime, where this has occurred were examined in terms of alloy development to achieve optimum mechanical properties while maintaining weldability. Specifically, base metal/filler metal systems susceptible to cracking were examined in terms of filler metal dilution. A mechanism for crack growth was presented based upon critical strain rate. Conditions needed for improved weldability through grain refinement were defined based upon the columnar-to-equiaxed solidification theory.