|Microstructure and Tensile Properties of a CoNi-Based Superalloy Fabricated by Selective Electron Beam Melting
|Year of Publication
|Murray SP, Pusch KM, Polonsky AT, Torbet CJ, Seward GGE, Nandwana P, Kirka MM, Dehoff RR, Zhou N, Forsik SAJ, Slye W, Pollock TM
|Tin S, Hardy M, Clews J, Cormier J, Feng Q, Marcin J, O'Brien C, Suzuki A
|Springer International Publishing
|Additive manufacturing, CoNi-based superalloys, Mechanical properties
Successful application of selective electron beam melting to a novel CoNi-based superalloy named SB-CoNi-10 is demonstrated. Crack-free as-printed microstructures exhibit excellent ductilities above 30% and ultimate tensile strengths above 1.1 GPa at room temperature in tension. Conventional post-processing consisting of a super-solvus hot isostatic pressing (HIP), a solution heat treatment (SHT), and a low-temperature aging has been applied to remove microstructural inhomogeneities present in the as-printed microstructure. The microstructures of the as-printed and HIP+SHT+Aged alloys have been investigated to determine the effect of post-processing heat treatments on the nanoscale γ/γ' microstructure and the mesoscale grain structure. Tensile tests have been conducted at room temperature and elevated temperatures above 850 ◦C to investigate mechanical properties in both the as-printed and HIP+SHT+Aged conditions. The high- temperature ductility and strength are strongly affected by the microstructure, with a mostly columnar-grained microstructure in the as-printed condition exhibiting superior ductility to the fully recrystallized microstructure in the HIP+SHT+Aged condition.