Influence of the finish cutting operations on the fatigue performance of Ti-6Al-4V parts produced by Selective Laser Melting

Ti6Al4V titanium alloy fatigue strength after AM- and machining-based process chains

“…The machined surface finish was evaluated by scanning an area of 0.67 £ 2.28 mm 2 through the Sensofar TM S-Neox optical profiler with a 20X magnification Nikon TM confocal objective. The arithmetic mean height Sa, reduced pit depth Svk, and skewness Ssk were considered in accordance to ISO 25,178À2:2012-Part 2, as informative in relation to the fatigue behaviour of the metal alloys; specifically, Svk and Ssk were identified as indicators of the presence of localized crack initiation sites [9].…”

Influence of Different Machining Processes on Fatigue life Performance of Engineered Surfaces: a Short Review

“…However, it is important to emphasize that both surface and subsurface defects as well as high residual stresses induced by the cutting process cause the large variation of experimental results. An important finding from the fatigue strength tests of the Ti-6Al-4V titanium alloy fabricated by the STM method and then finished by turning and milling, and polishing, was the lack of correlation with the roughness parameter Sa [20]. In turn, the fatigue strength was sensitive to changes in skewness Ssk because surfaces with Ssk > 0 work better under cyclical loads.…”

Machining of Additive Manufactured Metal Alloys

“…In [18] the fatigue strength of SLM Ti6Al4V samples was evaluated in the as-built condition and after finishing machining operations, and compared with the one of conventionally fabricated Ti6Al4V samples. The AM samples showed half the fatigue resistance of the wrought ones, and none of the different machining processes that were employed were able to assure a comparable fatigue resistance (see Figure 4 on the left where the fatigue strength is reported as a function of the skewness parameter Ssk that is usually considered indicative of the functionality of a surface in terms of fatigue).…”