High-temperature mechanical properties of Inconel-625: Role of carbides and delta phase

Liu, Dexue; Xiao, Zhao; Qin, Xiaoqiong; Ding, Yutian

doi:10.1080/02670836.2017.1300365

Cited by 30 publications

(3 citation statements)

References 24 publications

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“…It is worth noting that the continuous coarsening of the δ phase precipitates observed at 870 °C was not apparent at 700 °C, suggesting stability against significant coarsening at 700 °C, which is possibly due to the stabilization provided by the elastic energy of the strain field surrounded by the precipitates [ 49 ]. This limited growth of the δ phase precipitates during the long heat treatment at 700 °C is significant because the overgrown δ phase leads to reduced fracture strain [ 50 ]. Moreover, a recent review shows that direct aging at 700 °C for 24 h also leads to the highest reported UTS (1222 MPa) and yield strength (1012 MPa) for AM IN625, suggesting that the formation of smaller precipitates serves to improve the mechanical strength [ 51 ].…”

Section: Resultsmentioning

confidence: 99%

Solid-State Transformation of an Additive Manufactured Inconel 625 Alloy at 700 °C

et al. 2021

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Inconel 625, a nickel-based superalloy, has drawn much attention in the emerging field of additive manufacturing (AM) because of its excellent weldability and resistance to hot cracking. The extreme processing condition of AM often introduces enormous residual stress (hundreds of MPa to GPa) in the as-fabricated parts, which requires stress-relief heat treatment to remove or reduce the internal stresses. Typical residual stress heat treatment for AM Inconel 625, conducted at 800 °C or 870 °C, introduces a substantial precipitation of the δ phase, a deleterious intermetallic phase. In this work, we used synchrotron-based in situ scattering and diffraction methods and ex situ electron microscopy to investigate the solid-state transformation of an AM Inconel 625 at 700 °C. Our results show that while the δ phase still precipitates from the matrix at this temperature, its precipitation rate and size at a given time are both smaller when compared with their counterparts during typical heat treatment temperatures of 800 °C and 870 °C. A comparison with thermodynamic modeling predictions elucidates these experimental findings. Our work provides the rigorous microstructural kinetics data required to explore the feasibility of a promising lower-temperature stress-relief heat treatment for AM Inconel 625. The combined methodology is readily extendable to investigate the solid-state transformation of other AM alloys.

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Section: Resultsmentioning

confidence: 99%

Solid-State Transformation of an Additive Manufactured Inconel 625 Alloy at 700 °C

et al. 2021

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“…On the contrary, at 760 °C, the elongations to failure decreased significantly, especially after ST. Thus, the two alloys manifested the so-called elevated temperature ductility loss (

) observed in many Ni-based alloys [ 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 ]. This ductility loss reached its maximum after the solution treatment, and despite the dissolution of the δ phase, chemical homogenization and microstructure coarsening resulted from the treatment.…”

Section: Discussionmentioning

confidence: 99%

Effect of Fe and C Contents on the Microstructure and High-Temperature Mechanical Properties of IN625 Alloy Processed by Laser Powder Bed Fusion

Kreitcberg

Braïlovski

2022

Materials

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Two alloys with different Fe and C contents were studied to assess the influence of their compositions on the microstructure and mechanical properties of Ni-based Inconel 625 superalloy processed by laser powder bed fusion and subjected to stress relief annealing (870 °C) and a solution treatment (1120 °C). It was concluded that the alloy with a higher Fe content (~4 wt.% as compared to ~1 wt.%) manifests a greater propensity to segregate Nb and Mo elements during printing and form δ phase particles during the stress relief annealing. On the other hand, the alloy with a higher C content (~0.04 wt.% compared to ~0.02 wt.%) exhibits a greater tendency to form M6C carbides during the solution treatment. No effects of the Fe and C content variations on the room temperature mechanical properties were observed. On the contrary, an increase in the C content resulted in a 40% lower high-temperature (760 °C) ductility of the laser powder bed fused and post-processed IN625 alloy, without affecting its strength characteristics.

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“…Ni-based superalloy Inconel 625 (IN625) is a popular material for gas turbine applications characterized by good high temperature strength, creep resistance, corrosion resistance and excellent weldability [7][8][9][10]. Due to this excellent weldability, fabrication of IN625 by SLM is particularly appropriate and has been properly optimized [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

A novel approach to the production of NiCrAlY bond coat onto IN625 superalloy by selective laser melting

Lee

Terner

Copin

et al. 2020

Additive Manufacturing

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The present study investigated for the first time the feasibility of producing by Selective Laser Melting (SLM) a NiCrAlY bond coat material directly onto an IN625 substrate itself produced by SLM. A typical parameters optimization was conducted by varying laser power (P) and scanning speed (v). Single-line scanning tracks and two-layer coatings were carried out and analyzed for 15 different P/v conditions. Several criteria were defined for the selection of appropriate SLM parameters. The results showed significant remelting of the underlying substrate, which is a typical feature of SLM manufacturing. This led to the formation of an intermediate dilution zone characterized by substantial mixing between IN625 superalloy substrate and NiCrAlY bond coat suggesting excellent metallurgical bonding. Optimum processing conditions were found for P = 250 W and v = 800 mm/s. It produced a dense 242 μm thick bond coat including a 36% dilution zone. The SLMed < NiCrAlY-IN625 > system exhibited a smooth microhardness profile slightly increasing from 275 Hv in the bond coat to 305 Hv in the substrate. A progressive Al concentration distribution between the phases and low residual stress levels were found in the system. This suggested that SLM might be a valuable alternative manufacturing process for bond coat systems promoting excellent adhesion for high temperature applications.

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High-temperature mechanical properties of Inconel-625: Role of carbides and delta phase

Cited by 30 publications

References 24 publications

Solid-State Transformation of an Additive Manufactured Inconel 625 Alloy at 700 °C

Solid-State Transformation of an Additive Manufactured Inconel 625 Alloy at 700 °C

Effect of Fe and C Contents on the Microstructure and High-Temperature Mechanical Properties of IN625 Alloy Processed by Laser Powder Bed Fusion

A novel approach to the production of NiCrAlY bond coat onto IN625 superalloy by selective laser melting

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