High Cycle Fatigue of Laser Beam Deposited Ti-6Al-4V and Inconel 718

An overview of Direct Laser Deposition for additive manufacturing; Part II: Mechanical behavior, process parameter optimization and control

“…Tensile fatigue tests were performed at a stress ratio of = 0.1. Before machining and polishing specimens to a roughness a < 0.2 μm, a heat treatment schedule was [44]. Results indicate that the fatigue strength of a laser-deposited Inconel 718 specimen in midlife and long life regimes may be comparable with wrought Inconel 718.…”

“…pores and inclusion) than microstructure. Lack of bonding between layers and the presence of defects have been reported in [44] as the main reasons for the lower fatigue resistance of LENS Inconel 718 in very high-cycle regime -where a large portion of the total fatigue life is spent towards crack initiation, as shown in Fig. 10(a).…”

“…multi-track) parts is reported to be higher than those of thin-wall parts [44]. As a result, flat tensile specimens typically exhibit higher yield and ultimate stresses as well as lower elongation-to-failure than round specimens.…”

“…A summary of building orientation effects, e.g. X-direction (parallel) versus Y-direction (perpendicular), on tensile properties for several materials are listed in Table 3 [42,44,57]. This anisotropic behavior, as evidenced in Table 3, can be explained by the presence of weak interfacial layers parallel to the crack, in Z-and Y-directions, providing an easy path for shear bands [24,32].…”

“…As a result, flat tensile specimens typically exhibit higher yield and ultimate stresses as well as lower elongation-to-failure than round specimens. These effects may originate from microstructural variation caused by time-variant cooling rates during fabrication [44].…”