Effect of liquid nitrogen cryogenic cooling during wire arc directed energy deposition of nickel aluminum bronze

The effect of liquid nitrogen (LN) cryogenic cooling during gas metal arc directed energy deposition (DED) additive manufacturing (AM) of nickel aluminum bronze (NAB) was investigated. A commercially available LN spray cooling system was incorporated into the DED process for interpass temperature control and duty cycle optimization. Reductions in total build time and distortion were measured for single-bead wall and multi-layer block deposits. Strength and ductility requirements of the NAB wire and base material were met. In agreement with experimental results, coupled thermal-mechanical finite element analysis of DED AM with an active cooling source predicted a reduction in build time, and in residual stress build-up and distortion. Overall, the results of this study demonstrate that LN cryogenic cooling can be used to control interpass temperature without adversely affecting NAB build properties and offers opportunities for immediate transition into NAB DED applications.