Fatigue Crack Growth Rate Behaviour of an Additive Manufactured Nickel-Base Superalloy Inconel 718

Additive manufacturing (AMAdditive manufacturing (AM)) is fast replacing conventional processing route for the fabrication of near net-shape objects having a combination of intricate shapes and size. Inconel 718Inconel 718 is a nickelNickel-base superalloySuperalloys, that is primarily chosen for use in the forged condition for a spectrum of gas turbine applications. Understanding the damage tolerance behavior of such a materialMaterials is one of the primary requirements for its selection and use in such applications. In the present study, standard tensile and compact tension (CT) specimens of Inconel 718Inconel 718 materialMaterials were fabricated using the selective laser meltingSelective laser melting (SLM) technique of additive manufacturingAdditive manufacturing (AM). Preliminary track tests were conducted and optimized processProcess parameters were used for additive manufacturingAdditive manufacturing (AM) or printing of the test specimens. Standard procedure, in accordance with procedures detailed in the standard ASTM E 647, was followed for conducting the constant amplitude fatigue crack growthFatigue crack growth rate (FCGR) tests at four different stress ratios, namely: R = 0.1, R = 0.3, R = 0.5, and R = 0.7. Interestingly, the effect of stress ratio was minimum on crackCrack growth rate in the Paris regime, while the threshold (Kth) and maximum stress intensity factor (Kmax) values were observed to be noticeably affected. Evidence from fractographyFractography observations of the cyclically deformed and failed test specimens is corroborated with the test results.