| Abstract Scope |
Cast and wrought Cu-Ni 70-30 is widely used in marine applications. To improve schedule, reduce costs, and meet high-mix low-volume part demands in shipbuilding, metal additive manufacturing (AM) capabilities using wire arc directed energy deposition (WA-DED) and laser power bed fusion (L-PBF) are needed. The frequent use of welding in the Navy necessitates that material produced by any means is weldable and that any unique limitations or risks are well-understood. Hence, this program compares weldability of Cu-Ni 70-30 alloy AM material to that of its wrought and cast alternatives. Solidification cracking (SC) and liquation cracking (LC) tests were performed on cast, wrought, L-PBF, and WA-DED plates and rods. The Transvarestraint test (TVT) was used to characterize SC susceptibility, while the spot Varestraint test (SVT) and hot ductility test (HDT) were used to characterize LC susceptibility. The TVT and SVT use applied strains to determine the maximum crack distance (MCD) in either the fusion zone or heat affected zone, which are then correlated to the solidification cracking temperature range (SCTR) or the liquation cracking temperature range (LCTR). The total number of cracks (TNC), threshold strain for cracking (εc), and crack saturated strain (εs) are also determined. The HDT is performed in a Gleeble™ thermo-mechanical simulator to determine the nil ductility temperature (NDT), nil strength temperature (NST), and ductility recovery temperature (DRT). The LCTR is calculated by taking the difference between the NST and DRT. |