Unnotched fatigue of Inconel 718 produced by laser beam-powder bed fusion at 25 and 600°C

A review on isothermal rotating bending fatigue failure: Microstructural and lifetime modeling of wrought and additive manufactured alloys

“…There is a good chance this phenomenon is connected to the phase and its rafting, which can affect the persistence of slipping bands and twining in certain alloys 68,69 . The fatigue limit in AM'd Inconel 718 was published by Radhakrishnan et al 62 in the RBF test, and Nezhadfar et al 70 reported results that were comparable to those in the conventional fatigue test. During the aging treatment of the Ni‐based superalloy at temperatures between 850°C and 950°C in wrought material, Yu et al 71 found that the segregation of carbon, chromium, and molybdenum at the grain boundaries promoted the development of M 23 C 6 carbides.…”

“…Comparison of wrought and AM'd S‐N data in RB test for Ti‐6Al‐4V, Al‐6061, 316L stainless steel, and Inconel 718. Purple signs show Al‐6061 RB test S‐N data for AM and wrought materials, 65 red signs for 316L SS RB test S‐N data of AM and wrought materials, 55 green signs for Inconel 718 AM and wrought materials, 62 blue signs for Ti‐6Al‐4V AM 41 and wrought materials, 66 and yellow signs for AM and wrought Ti‐6Al‐4V in 250°C and room temperature 50 . [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…The accumulation of severe dislocations can cause an excessive stress concentration around the carbide chains, which in turn encourages the initiation and spread of microcracks, which ultimately fail the alloy. Radhakirishnan et al 62 evaluated the fatigue behavior of AM'd Inconel 718 in the RBF test, but they did not verify the effect of carbides on the microstructure. Because of the greater possibility of precipitation at high temperatures, it is fair to expect that the impact of carbides will be visible in AM'd materials, just as it is in wrought materials.…”

“…S‐N curves of SLM'ed and wrought Inconel 718 in RB test (wrought Inconel 718 S‐N data extracted from Kawagoishi et al and Chen et al, 72,73 AM'd materials S‐N data extracted from Radhakrishnan et al and Kelley 62,74 ). [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…Radhakrishnan et al 62 recently researched the behavior of AM'd Inconel 718 in IT‐RBF. Figure 11A is a representative image that was obtained by X‐ray micro‐computed tomography (XRMCT) that shows the porosity distribution in three dimensions in the bulk material.…”