Microstructure and Tensile Properties of a CoNi-Based Superalloy Fabricated by Selective Electron Beam Melting

TitleMicrostructure and Tensile Properties of a CoNi-Based Superalloy Fabricated by Selective Electron Beam Melting
Publication TypeConference Paper
Year of Publication2020
AuthorsMurray SP, Pusch KM, Polonsky AT, Torbet CJ, Seward GGE, Nandwana P, Kirka MM, Dehoff RR, Zhou N, Forsik SAJ, Slye W, Pollock TM
EditorTin S, Hardy M, Clews J, Cormier J, Feng Q, Marcin J, O'Brien C, Suzuki A
Conference NameSuperalloys 2020
PublisherSpringer International Publishing
ISBN Number9783030518349
KeywordsAdditive 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.