Functionally Graded Alloys Obtained by Additive Manufacturing

Niendorf, Т.; Leuders, Stefan; Riemer, Andre; Brenne, F.; Richard, Hans Albert; Schwarze, Dieter

doi:10.1002/adem.201300579

Cited by 107 publications

(56 citation statements)

References 17 publications

(32 reference statements)

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“…The average grain size for the AM sample was 21 ± 6 μm and anisotropic (elongated in the build direction) whilst the conventional sample was 13 ± 3 μm and equi-axed. This anisotropy in AM samples has been noted by others 5 and is likely due to the large thermal gradients that are set up during the build process when melt pools form and preferentially orientate as they cool. Results from AM cylinders are shown in Fig 3. and Fig 4. alongside simulations completed using the Eulerian hydrocode CTH.…”

Section: Resultssupporting

confidence: 68%

The fracture and fragmentation behaviour of additively manufactured stainless steel 316L

Amott¹,

Harris²,

Winter³

et al. 2017

AIP Conference Proceedings

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Abstract.Expanding cylinder experiments using a gas gun technique allow investigations into the ductility of metals and the fracture and fragmentation mechanisms that occur during rapid tensile failure. These experiments allow the radial strain-rate of the expansion to be varied in the range 10 2 to 10 4 s -1 . Presented here is a comparative study of the fracture and fragmentation behaviour of rapidly expanded stainless steel 316L cylinders manufactured from either a wrought bar or additive manufacturing techniques. The results show that in the strain-rate regime studied, an additively manufactured cylinder failed at a higher strain and produced larger fragment widths when compared to cylinders manufactured from a wrought bar. In addition, an investigation into the role of macroscopic elongated voids that were introduced into the cylinder wall, at an angle of 45 to the cylinder radius, was undertaken. A comparison between experimental and simulated results (using the Eulerian hydrocode CTH) was also completed.

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Section: Resultssupporting

confidence: 68%

The fracture and fragmentation behaviour of additively manufactured stainless steel 316L

Amott¹,

Harris²,

Winter³

et al. 2017

AIP Conference Proceedings

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“…due to the neighbouring scan track or subsequent layer being generated, the grains of the already solidified materials become altered by the secondary heat input [38]. This behaviour is commonly referred to as epitaxial grain growth, describing the tendency of needle-like grain growth towards the heat source [41,42]. Due to this tendency, the grains of 1.4404 grew through the individual layers (in direction of the heat source), causing an interlocking of the individual layers ( Figure 9).…”

Section: Comprehensive Analysis Of the Directional Dependencies And Tmentioning

confidence: 99%

On the Anisotropic Mechanical Properties of Selective Laser Melted Stainless Steel

Hitzler

Hirsch

Heine

et al. 2017

Preprint

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Abstract:The thorough description of the peculiarities of additively manufactured structures represents a current challenge for aspiring freeform fabrication methods, such as the selective laser melting (SLM). All of which have an immense advantage in the fast fabrication (no special tooling or moulds required), the geometrical flexibility in the design of components, and their efficiency when only low quantities are required. However, designs demand the precise knowledge of the material properties, which in case of additively manufactured structures are anisotropic and, under certain circumstances, in addition of an inhomogeneous nature. Furthermore, these characteristics are highly dependent on the fabrication settings. Within this study, the anisotropic tensile properties of selective laser melted stainless steel (1.4404, 316L) are investigated: The Young's modulus ranged from 148 GPa to 227 GPa, the ultimate tensile strength from 512 MPa to 699 MPa and the breaking elongation ranged, respectively, from 12% to 43%. The results were compared to related studies, in order to classify the influence of the fabrication settings. Furthermore, the influence of the chosen raw material was addressed by comparing deviations on the directional dependencies reasoned by differing microstructural developments during manufacture. Stainless steel was found to possess its maximum strength at a 45° layer versus loading offset, which is precisely where AlSi10Mg was previously reported to be at its weakest.

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“…In any case, the physical quantities dominating the solidification and resulting microstructures were the thermal gradient G in combination with the solidification velocity v, as discussed in more detail by Gäumann et al for epitaxial laser metal forming [21]. In [22] it was shown that, applying different lasers in distinct areas, fully intact parts of locally different mechanical behaviour can be directly produced.…”

Section: Introductionmentioning

confidence: 97%

Microstructural design of Ni-base alloys for high-temperature applications: impact of heat treatment on microstructure and mechanical properties after selective laser melting

et al. 2016

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Optimising the microstructure and mechanical performance of Ni-base alloys is vital to achieve higher efficiencies in many high-temperature applications. With the recent emergence of the additive manufacturing technologies, new possibilities with respect to freedom of design and microstructure manipulation are opened up. This study aims at adjusting a microstructure suited for high-temperature applications by employing high-power selective laser melting. The parts are subjected to diverse post-process heat treatments to examine if the desired microstructural features can be preserved and proper precipitations can be formed. Results obtained by electron backscatter diffraction show a high resistance against recrystallization in the temperature range contemplated. Still, process-induced formation of undesired brittle Laves phase particles was observed via transmission electron microscopy and backscattered electron imaging. Mechanical tests in the form of hardness measurements, tensile tests, and high-temperature compression creep tests proved a high dependency of the performance on the post-processing treatment conducted. Hardness, yield strength and elongation at failure at room temperature are adequate in comparison with conventionally processed materials. Hightemperature compression creep tests emphasised the importance of solution annealing to enable for proper precipitation of strengthening phases during subsequent ageing.

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Functionally Graded Alloys Obtained by Additive Manufacturing

Cited by 107 publications

References 17 publications

The fracture and fragmentation behaviour of additively manufactured stainless steel 316L

The fracture and fragmentation behaviour of additively manufactured stainless steel 316L

On the Anisotropic Mechanical Properties of Selective Laser Melted Stainless Steel

Microstructural design of Ni-base alloys for high-temperature applications: impact of heat treatment on microstructure and mechanical properties after selective laser melting

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