Characterization of fatigue crack growth behavior in LENS fabricated Ti-6Al-4V using high-energy synchrotron x-ray microtomography

Sandgren, Hayley Rose; Zhai, Yuanliang; Shade, Paul A.; Schuren, Jay C.; Groeber, Michael A.; Kenesei, Péter; Gavras, Anastasios G.

doi:10.1016/j.addma.2016.09.002

Cited by 35 publications

(22 citation statements)

References 30 publications

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“…The microstructure of LMD-fabricated Ti-6Al-4V components is composed of acicular α' martensite. Figure 7a,b shows such a microstructure as was also described in other studies [14][15][16][17]20]. The α' martensitic microstructure produced after LMD manufacturing of Ti-6AL-4V is located inside the elongated prior β grains.…”

Section: Laser Metal Deposition (Lmd)supporting

confidence: 77%

“…With a further decrease in temperature, the α phase grows into the β grains, either in a platelet form or along the β grain boundaries, depending on the cooling rate. The cooling rates also affect the size and distribution of α laths inside the prior β grains [15][16][17]. The thickness of α laths decreases if the cooling rates are increased.…”

Section: Parameters Affecting Am Materials Propertiesmentioning

confidence: 99%

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Variations in the Surface Integrity of Ti-6Al-4V by Combinations of Additive and Subtractive Manufacturing Processes

et al. 2020

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Additive manufacturing (AM) has recently been accorded considerable interest by manufacturers. Many manufacturing industries, amongst others in the aerospace sector, are already using AM parts or are investing in such manufacturing methods. Important material properties, such as microstructures, residual stress, and surface topography, can be affected by AM processes. In addition, a subtractive manufacturing (SM) process, such as machining, is required for finishing certain parts when accurate tolerances are required. This finish machining will subsequently affect the surface integrity and topography of the material. In this research work, we focused on the surface integrity of Ti-6Al-4V parts manufactured using three different types of AM and finished using an SM step. The aim of this study was to gain an understanding on how each process affects the resulting surface integrity of the material. It was found that each AM process affects the materials’ properties differently and that clear differences exist compared to a reference material manufactured using conventional methods. The newly generated surface was investigated after the SM step and each combination of AM/SM resulted in differences in surface integrity. It was found that different AM processes result in different microstructures which in turn affect surface integrity after the SM process.

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Section: Laser Metal Deposition (Lmd)supporting

confidence: 77%

Section: Parameters Affecting Am Materials Propertiesmentioning

confidence: 99%

Variations in the Surface Integrity of Ti-6Al-4V by Combinations of Additive and Subtractive Manufacturing Processes

et al. 2020

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“…There are several instances from the literature, which record varying trends of tensile behavior and ductility for the same material printed by DED. For instance, in one study, the tensile strength of DED fabricated Ti-6Al-4V was found to be similar to wrought manufactured Ti-6Al-4V, but with reduced ductility [93]. Another study showed that DED processed Ti-6Al-4V has a higher tensile strength due to a finer microstructure as compared with wrought alloy, but still exhibits lower ductility, due to a combination of the fine microstructure and the presence of internal defects [94].…”

Section: Tensile Strengthmentioning

confidence: 99%

State of the Art in Directed Energy Deposition: From Additive Manufacturing to Materials Design

2019

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Additive manufacturing (AM) is a new paradigm for the design and production of high-performance components for aerospace, medical, energy, and automotive applications. This review will exclusively cover directed energy deposition (DED)-AM, with a focus on the deposition of powder-feed based metal and alloy systems. This paper provides a comprehensive review on the classification of DED systems, process variables, process physics, modelling efforts, common defects, mechanical properties of DED parts, and quality control methods. To provide a practical framework to print different materials using DED, a process map using the linear heat input and powder feed rate as variables is constructed. Based on the process map, three different areas that are not optimized for DED are identified. These areas correspond to the formation of a lack of fusion, keyholing, and mixed mode porosity in the printed parts. In the final part of the paper, emerging applications of DED from repairing damaged parts to bulk combinatorial alloys design are discussed. This paper concludes with recommendations for future research in order to transform the technology from “form” to “function,” which can provide significant potential benefits to different industries.

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“…To this end, Figure 6 presents the da/dN versus ∆K curves associated with the growth of small cracks given in [40] for post-heat-treated LENS Ti-6Al-4V where the surfaces were not machined. For comparison, Figure 6 also presents:…”

Section: Small Crack Growth In Lens Ti-6al-4vmentioning

confidence: 99%

Crack Growth in a Range of Additively Manufactured Aerospace Structural Materials

et al. 2018

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The aerospace industry is now beginning to adopt Additive Manufacturing (AM), both for new aircraft design and to help improve aircraft availability (aircraft sustainment). However, MIL-STD 1530 highlights that to certify airworthiness, the operational life of the airframe must be determined by a damage tolerance analysis. MIL-STD 1530 also states that in this process, the role of testing is merely to validate or correct the analysis. Consequently, if AM-produced parts are to be used as load-carrying members, it is important that the d a / d N versus ΔK curves be determined and, if possible, a valid mathematical representation determined. The present paper demonstrates that for AM Ti-6Al-4V, AM 316L stainless steel, and AM AerMet 100 steel, the d a / d N versus ΔK curves can be represented reasonably well by the Hartman-Schijve variant of the NASGRO crack growth equation. It is also shown that the variability in the various AM d a / d N versus Δ K curves is captured reasonably well by using the curve determined for conventionally manufactured materials and allowing for changes in the threshold and the cyclic fracture toughness terms.

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Characterization of fatigue crack growth behavior in LENS fabricated Ti-6Al-4V using high-energy synchrotron x-ray microtomography

Cited by 35 publications

References 30 publications

Variations in the Surface Integrity of Ti-6Al-4V by Combinations of Additive and Subtractive Manufacturing Processes

Variations in the Surface Integrity of Ti-6Al-4V by Combinations of Additive and Subtractive Manufacturing Processes

State of the Art in Directed Energy Deposition: From Additive Manufacturing to Materials Design

Crack Growth in a Range of Additively Manufactured Aerospace Structural Materials

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