Solidification Cracking Susceptibility of Commercial Copper-Based Feedstocks

Solidification Cracking Susceptibility of Commercial Copper-Based FeedstocksCopper alloys offer an excellent balance of corrosion resistance and strength and are of interest for marine and other applications. Research on the mechanical properties and microstructure of welded and additively manufactured copperbased alloys has been conducted; however, further work is needed to understand their susceptibility to solidification cracking. The weldability of six commercially available wire feedstocks deposited with gas metal arc directed energy deposition was evaluated using the Sigmajig weldability test. Fullpenetration autogenous gas tungsten arc remelts were performed at various applied stresses, and solidification cracking was measured. At an applied stress of 10 MPa, the alloys were ranked from most to least weldable as follows: ERCuAl, ERCuNiAl, ERCuMnNiAl, ERCuNi, ERCuSi, and ERCu. The Kou crack susceptibility index (CSI) was applied to these compositions, and the CSI ranking matched the Sigmajig ranking of cracking susceptibility. Fractography showed dendrites on the fracture surface in all samples, confirming solidification cracking, except in ERCuAl samples, which exhibited extensive microvoid coalescence, indicating significant plastic deformation before sample failure. This work provides a deeper understanding of solidification cracking behavior, which will inform alloy selection and cracking mitigation in the growing field of additive manufacturing using copper-based feedstocks.