The role of texturing and microstructure evolution on the tensile behavior of heat-treated Inconel 625 produced via laser powder bed fusion

Marchese, Giulio; Parizia, Simone; Rashidi, Masoud; Saboori, Abdollah; Manfredi, Diego; Ugues, Daniele; Lombardi, Mariangela; Hryha, Eduard; Biamino, Sara

doi:10.1016/j.msea.2019.138500

Cited by 117 publications

(53 citation statements)

References 31 publications

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“…The dislocations density of SR in Figure 3 appears slightly lower compared to AB; however, drawing a conclusion is difficult due to the very small volume of analysis allowed by TEM (~100 μm 3 ). Significant precipitation of the δ-phase has been detected in these conditions similarly to a previous research [ 10 ], which is consistent with the more rapid precipitation kinetics of the δ-phase as a result of segregation mentioned earlier. δ-phase formation under similar thermal exposure (from 700 to 900 °C) for prolonged times (200 h) was also reported, revealing that segregations tend to limit its growth [ 33 ].…”

Section: Resultssupporting

confidence: 92%

“…The high density of dislocations is indicative of accommodation for residual thermal stress due to the rapid cooling and heating cycles inherent to the LPBF process and therefore illustrates the high levels of strain energy accumulated within the material. This peculiar microstructure is typical of alloys produced by AM powder bed fusion processes such as LPBF [ 6 , 8 , 9 , 10 , 28 , 29 , 30 , 31 ].…”

Section: Resultsmentioning

confidence: 98%

“…Alloy 625 is a popular Nb-rich solid-solution strengthened Ni-based superalloy characterized by attractive high temperature resistance for applications in aerospace and land-based gas turbines in particular [ 11 , 12 , 13 , 14 ]. In previous works, we found that the microstructure fully recrystallized upon solution treatment above 1150 °C [ 8 , 9 , 10 ]. This is remarkable as for Alloy 625, and most polycrystalline materials for that matter, recrystallization is usually achieved by application of external stress such as cold working followed by heating above the recrystallization temperature (which depends on the amount of cold work).…”

Section: Introductionmentioning

confidence: 99%

“…In previous studies, the effects of different heat treatments on microstructure and associated tensile properties of Alloy 625 produced by LPBF were investigated [ 8 , 9 , 10 ]. Alloy 625 is a popular Nb-rich solid-solution strengthened Ni-based superalloy characterized by attractive high temperature resistance for applications in aerospace and land-based gas turbines in particular [ 11 , 12 , 13 , 14 ].…”

Section: Introductionmentioning

confidence: 99%

“…The as-built microstructure of Alloy 625 produced by LPBF is virtually always characterized by strong texture, large anisotropy, inhomogeneous solute distribution, a very fine dendritic structure, and a very high dislocations density primarily within the interdendritic regions [ 6 , 8 , 9 , 10 , 28 , 29 , 30 , 31 ]. The very high dislocations density, in particular, is the result of the peculiar solidification and thermal history inherited from LPBF, thus highlighting the high degree of strain energy previously mentioned.…”

Section: Introductionmentioning

confidence: 99%

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Electron Backscattered Diffraction to Estimate Residual Stress Levels of a Superalloy Produced by Laser Powder Bed Fusion and Subsequent Heat Treatments

et al. 2020

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Metal Additive Manufacturing and Laser Powder Bed Fusion (LPBF), in particular, have come forth in recent years as an outstanding innovative manufacturing approach. The LPBF process is notably characterized by very high solidification and cooling rates, as well as repeated abrupt heating and cooling cycles, which generate the build-up of anisotropic microstructure and residual stresses. Post-processing stress-relieving heat treatments at elevated temperatures are often required in order to release some of these stresses. The effects of 1 h–hold heat treatments at different specific temperatures (solutionizing, annealing, stress-relieve and low-temperature stress-relieve) on residual stress levels together with microstructure characterization were therefore investigated for the popular Alloy 625 produced by LPBF. The build-up of residual stress is accommodated by the formation of dislocations that produce local crystallographic misorientation within grains. Electron backscattered diffraction (EBSD) was used to investigate local misorientation by means of orientation imaging, thereby assessing misorientation or strain levels, in turn representing residual stress levels within the material. The heavily constrained as-built material was found to experience full recrystallization of equiaxed grains after solutionizing at 1150 °C, accompanied by significant drop of residual stress levels due to this grains reconfiguration. Heat treatments at lower temperatures however, even as high as the annealing temperature of 980 °C, were found to be insufficient to promote recrystallization though effective to some extent to release residual stress through apparently dislocations recovery. Average misorientation data obtained by EBSD were found valuable to evaluate qualitatively residual stress levels. The effects of the different heat treatments are discussed and suggest that the peculiar microstructure of alloys produced by LPBF can possibly be transformed to suit specific applications.

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Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electron Backscattered Diffraction to Estimate Residual Stress Levels of a Superalloy Produced by Laser Powder Bed Fusion and Subsequent Heat Treatments

et al. 2020

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Microstructure and Mechanical Properties of Thick‐Walled Inconel 625 Alloy Manufactured by Wire Arc Additive Manufacture with Different Torch Paths

Jiang

Zhang

et al. 2020

Adv Eng Mater

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Wire arc additive manufacture (WAAM) technology has attracted more and more attention. WAAM technology provides a way to manufacture a large‐scale part at a low cost and with less material loss. Inconel 625 alloys are widely used for their excellent mechanical properties and corrosion resistance. Therefore, it is important to investigate the performance of Inconel 625 alloy in WAAM. Herein, cold metal transfer (CMT) arc is used as the heat source to fabricate thick‐walled parts of Inconel 625 alloy by WAAM, and study the difference between microstructure and mechanical properties under the different torch trajectories. The result shows that the grains inside the parts are all thick dendrites and show the trend of epitaxial growth. The thermal input of the oscillation additive is higher than the two‐pass multilayer additives, and the Laves phase also precipitated more. The maximum tensile strength occurs in parallel sampling close to the substrate, which is 693.5 ± 12.6 and 751.2 ± 17.6 MPa in oscillation and two‐pass multilayer modes, respectively. The maximum elongation is obtained in the vertical direction is 60 ± 1.0% and 60 ± 1.1%. The anisotropies are 4% and 4.5%, respectively. The maximum hardness value under the two torch trajectories also appears close to the substrate.

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Microstructural, Mechanical, and Tribological Evolution under Different Heat Treatment Conditions of Inconel 625 Alloy Fabricated by Selective Laser Melting

Ferraresi

Avanzini

Cecchel³

et al. 2021

Adv Eng Mater

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Additive manufacturing (AM) can be particularly advantageous to manufacture components designed to meet challenging structural requirements. Selective laser melting (SLM) microstructure is different than that obtained by traditional manufacturing process; in particular, mechanical and microstructural features achieved herein are influenced by the entire thermal history, including the manufacturing process and the heat treatment (HT) with relevant role of the slow cooling rate adopted. In fact, both the process and the HTs can significantly modify the microstructure and related mechanical and tribological properties. To better understand how mechanical response can be tuned to meet different requirements, in this article the effects of four different vacuum HTs on microstructures, mechanical properties, and wear behavior of Inconel 625 produced with SLM are deeply investigated. In general, the results confirm that HT can significantly change the microstructure and mechanical or tribological properties of Inconel 625. Among the examined HT, solution + aging and direct aging improve the strength of the alloy, whereas annealing leads to recrystallization, reducing strength in favor of ductility. Stress relieving does not significantly change the microstructure and mechanical properties. Considering tribological behavior, only direct aging HT leads to a remarkable improvement, with a reduction in friction coefficient and wear rate.

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The role of texturing and microstructure evolution on the tensile behavior of heat-treated Inconel 625 produced via laser powder bed fusion

Cited by 117 publications

References 31 publications

Electron Backscattered Diffraction to Estimate Residual Stress Levels of a Superalloy Produced by Laser Powder Bed Fusion and Subsequent Heat Treatments

Electron Backscattered Diffraction to Estimate Residual Stress Levels of a Superalloy Produced by Laser Powder Bed Fusion and Subsequent Heat Treatments

Microstructure and Mechanical Properties of Thick‐Walled Inconel 625 Alloy Manufactured by Wire Arc Additive Manufacture with Different Torch Paths

Microstructural, Mechanical, and Tribological Evolution under Different Heat Treatment Conditions of Inconel 625 Alloy Fabricated by Selective Laser Melting

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