1,720,988 research outputs found
Influence of surface orientation and segmentation on the notch fatigue behavior of as-built DMLS Ti6Al4V
No full textDesign and qualification of load-bearing metal parts produced by the additive manufacturing technology is a critical issue. Such metal parts are complex in geometry with notches that are critical locations under fatigue loading. Notch surfaces are typically in the as-built state because post-fabrication surface finishing is not a viable approach in most applications. Here fatigue experiments using notched specimens produced according to different orientations with respect to build direction are presented and used to discuss the notch fatigue behavior of DMLS Ti6Al4V. Notch fatigue factors depend on the process itself and on fabrication details such as up-skin versus down-skin surface orientation, stair-stepping of the notch surface due to the layer-by-layer segmentation and intrinsic as-built surface roughness
On the link between as-built surface quality and fatigue behavior of additively manufactured Inconel 718
No full textInconel 718 is widely used in challenging structural applications because of its excellent high temperature mechanical properties. Selective Laser Melting (SLM) of Inconel 718 powder is increasingly used to fabricate customized parts for jet engines. The surface quality of SLM parts is influenced by powder characteristics, process parameters and the layer-wise fabrication. The as-built fatigue behavior is negatively affected by the inferior surface quality of SLM parts compared to machined version. Here the fatigue behavior of SLM Inconel 718 is investigated using specimens fabricated with two different SLM systems and different directions of applied stress with respect to build direction. Fatigue test results are interpreted in the light of metallographic and fractographic investigations
Near-surface structure and fatigue crack initiation mechanisms of as-built slm inconel 718
No full textChallenging structural applications such as customized jet engine parts are increasingly fabricated by Selective Laser Melting (SLM) of Inconel 718 powder. The as-built surface quality of SLM parts is however inferior of the machined version and the fatigue behavior is negatively affected. The as-built fatigue response of SLM Inconel 718 was quantified here using three sets of directional specimens. Since the surface quality is influenced by powder characteristics, process parameters and layer-wise fabrication, fatigue results showed a directional contribution that was interpreted using metallography and fractography
Microstructure and fatigue performace of additively manufactured AlSi10Mg
No full textLaser powder bed fusion technology (L-PBF) can readily fabricate near-net shape metal parts. Therefore, the automotive and aerospace industries have been investigating the L-PBF production of AlSi10Mg parts because of low specific density, good hardenability, and low powder costs. Further, local melting of the atomized powder and subsequent rapid solidification generates fine structures having mechanical properties that are competitive with conventionally produced Al alloys. If the products remain in the as-built state (i.e., no post fabrication heat treatment), residual stresses are expected in the part and are superimposed on the operating stress with often unpredictable effects on its fatigue life. As-built part surfaces are rough compared to machined surfaces with a negative influence on the fatigue strength of L-PBF AlSi10Mg parts. On the other hand, surface machining is not only expensive but often impossible for L-PBF parts due to their geometric complexity. This study investigates the fatigue behavior of L-PBF AlSi10Mg under the combined effect of untreated condition and as-built (i.e., rough) surface quality. Three sets of miniature specimens, each with a different orientation (A, B, C) with respect to the build direction were printed in an SLM 280 HL system operating with a layer thickness of 50 μm. Each set consisted of approx. 15 samples. The as-built samples were tested in cyclic plane bending at a load ratio R = 0 at a frequency of 25 Hz and a significant directional influence on the fatigue behavior quantified. To investigate the origin of this behavior, samples for each orientation were examined using metallographic techniques to determine the structure and quality of surfaces. Surface features depending on printing strategy and printing parameters of the different specimens qualitatively explain the observed directional fatigue behavior
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