Effect of Wall Thickness and Surface Conditions on Creep Behavior of a Single-Crystal Ni-Based Superalloy

Körber, Selina; Wolff-Goodrich, Silas; Völkl, Rainer; Glatzel, Uwe

doi:10.3390/met12071081

Cited by 5 publications

(4 citation statements)

References 28 publications

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“…Importantly, it should be emphasized that the casting pores are all eliminated in the two alloys with the help of HIP heat treatment. The presence of microporosity will harm the properties of Mar-M247, resulting in the scatter of creep performance [28]. The application of HIP heat treatment ensured the subsequent creep test results were not influenced by casting pores.…”

Section: As-cast and Heat-treated Microstructuresmentioning

confidence: 99%

Effect of Heat Treatment Schedules on Creep Performance of Ni-Based Superalloy Mar-M247 at 871 °C and 250 Mpa

Pan

Sui²,

Yu³

et al. 2023

Metals

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The effects of heat treatment (H1 and H2) on the creep behavior and microstructures of Mar-M247 at 871 °C/250 MPa are studied. The results show that the as-cast microstructure is composed of eutectics, γ phase, γ’ phase, MC and M23C6 carbides, while new M6C appears in heat-treated microstructures, indicating the transformation of carbides after heat treatments. The Mar-M247 is excellent, with over 1500 h of creep life, and H1 is 48% higher than H2. The addition of post-brazing and diffusion heat treatment in H2 is detrimental to creep resistance; the two steps promoted the transformation of MC into M23C6 in advance. The increase and coarsening of M23C6 would consume more γ-phase-forming elements, weakening the solution strengthening at grain boundaries. As a result, the resistance of the grain boundary and γ/γ’ interface to dislocation motion is significantly reduced, leading to the cracks’ initiation and propagation along the grain boundaries.

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Section: As-cast and Heat-treated Microstructuresmentioning

confidence: 99%

Effect of Heat Treatment Schedules on Creep Performance of Ni-Based Superalloy Mar-M247 at 871 °C and 250 Mpa

Pan

Sui²,

Yu³

et al. 2023

Metals

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“…the creep lifetimes of DD6 increased with the decrease of the specimen thickness slightly. Most of the investigations focused on thin‐walled specimens machined from bulk materials 32–34 . Through the creep experiments of casting specimens and machined specimens of nickel‐based single crystal superalloy MAR M247LC, Körber et al 34 found that there were differences in thickness debit effect of MAR M247LC specimens prepared in different ways, and the microstructure difference (such as initial porosity) caused by different processing methods is an important reason for this phenomenon.…”

Section: Introductionmentioning

confidence: 99%

“…Most of the investigations focused on thin-walled specimens machined from bulk materials. [32][33][34] Through the creep experiments of casting specimens and machined specimens of nickel-based single crystal superalloy MAR M247LC, Körber et al 34 found that there were differences in thickness debit effect of MAR M247LC specimens prepared in different ways, and the microstructure difference (such as initial porosity) caused by different processing methods is an important reason for this phenomenon. Texier et al 35 conducted high-temperature creep experiments with thin-wall specimens (50-200 μm), and the experimental results revealed heterogeneities in creep behavior at a mesoscopic scale, attributed to differences in creep strength between dendrite cores and interdendritic regions.…”

Section: Introductionmentioning

confidence: 99%

A thickness‐sensitive and orientation‐related creep lifetime prediction method of nickel‐based single crystal superalloy

Zhang

Wang

Liu

et al. 2023

Fatigue Fract Eng Mat Struct

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Considering the anisotropy of nickel‐based single crystal superalloy, an anisotropic creep lifetime prediction model based on slip plane damage is developed. The predicted results indicate that the lifetime prediction model could predict the creep lifetimes of nickel‐based single crystal superalloy with different orientations accurately. Furthermore, in order to reveal the damage mechanism of nickel‐based single crystal thin‐walled specimen, creep experiment and failure analysis of thin‐walled specimen are conducted, and there are obvious differences in damage mechanisms between surface and interior of the thin‐walled specimen. In this paper, both thickness debit effect and abnormal thickness debit effect are considered to be caused by the damage differences between surface and interior of the thin‐walled specimen, and zone‐based failure criteria considering thickness debit effect and abnormal thickness debit effect are proposed. Finally, combining the anisotropic creep lifetime prediction model and zone‐based failure criteria, the creep lifetime prediction of DD6 specimen with different thickness is conducted. The predicted lifetimes are within a scatter band of factor 2.26, and the predicted laws between creep lifetimes and thicknesses of the specimens are in good agreement with the experimental results, which verifies the rationality and accuracy of the thickness‐sensitive creep lifetime prediction method established in this paper.

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“…However, the addition of rhenium (Re) can significantly impede the growth of the γ′ phase and contribute to microstructural stability [ 26 ]. It is worth noting that previous investigations into the deformation mechanisms of SX superalloys during creep have mostly focused on temperatures below 1100 °C [ 27 ]. The behavior and deformation mechanisms during creep at temperatures exceeding 1100 °C have been rarely explored, despite the fact that Re addition at these temperatures promotes the precipitation of topologically close-packed (TCP) phases [ 28 , 29 , 30 ].…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution and Dislocation Mechanism of a Third-Generation Single-Crystal Ni-Based Superalloy during Creep at 1170 °C

Liu

2023

Materials

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The present study investigates the creep behavior and deformation mechanism of a third-generation single-crystal Ni-based superalloy at 1170 °C under a range of stress levels. Scanning electron microscopes (SEM) and transmission electron microscopes (TEM) were employed to observe the formation of a rafted γ′ phase, which exhibits a topologically close-packed (TCP) structure. The orientation relationship and elemental composition of the TCP phase and matrix were analyzed to discern their impact on the creep properties of the alloy. The primary deformation mechanism of the examined alloy was identified as dislocation slipping within the γ matrix, accompanied by the climbing of dislocations over the rafted γ′ phase during the initial stage of creep. In the later stages of creep, super-dislocations with Burgers vectors of a<010> and a/2<110> were observed to shear into the γ′ phase, originating from interfacial dislocation networks. Up to the fracture, the sequential activation of dislocation shearing in the primary and secondary slipping systems of the γ′ phase occurs. As a consequence of this alternating dislocation shearing, a twist deformation of the rafted γ′ phase ensued, ultimately contributing to the fracture mechanism observed in the alloy during creep.

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Effect of Wall Thickness and Surface Conditions on Creep Behavior of a Single-Crystal Ni-Based Superalloy

Cited by 5 publications

References 28 publications

Effect of Heat Treatment Schedules on Creep Performance of Ni-Based Superalloy Mar-M247 at 871 °C and 250 Mpa

Effect of Heat Treatment Schedules on Creep Performance of Ni-Based Superalloy Mar-M247 at 871 °C and 250 Mpa

A thickness‐sensitive and orientation‐related creep lifetime prediction method of nickel‐based single crystal superalloy

Microstructure Evolution and Dislocation Mechanism of a Third-Generation Single-Crystal Ni-Based Superalloy during Creep at 1170 °C

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