Very high cycle fatigue durability of an additively manufactured single-crystal Ni-based superalloy

Abstract

A single crystalline (SX) nickel-based superalloy additively manufactured (AM) by electron beam-based powder bed fusion (PBF-E) was investigated under very high cycle fatigue (VHCF) at 1,000 °C in fully reversed conditions (R ε = −1). Specimens processed using a classical Bridgman solidification route and the impact of a hot isostatic pressing (HIP) treatment were also considered. It is shown that the fatigue lifetime of the AM specimens is higher or in the same range of the Bridgman processed ones with the same chemical composition. All defect-free AM samples fail by surface initiation with very long VHCF lives. In the absence of metallurgical defects such as grain boundaries or pores, the superalloy chemical stability against oxidation governs VHCF failure. • Additively manufactured and Bridgman solidified CMSX-4 superalloy have comparable VHCF life under high temperature. • The superalloy chemistry controls the fatigue life of defect-free specimens. • Defect-free specimens fails by surface crack initiation. • The fatigue limit is controlled by the superalloy oxidation resistance at temperature of 1,000 °C.