Twin boundary fatigue crack nucleation in a polycrystalline Nickel superalloy containing non-metallic inclusions

Bergsmo, Alexander; Xu, Yingjie; Poole, Benjamin

doi:10.1016/j.jmps.2022.104785

Cited by 22 publications

(6 citation statements)

References 45 publications

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“…Inside the BTR, the ductility of the material is easily insufficient to accommodate the strain, and the wider BTR leads to higher susceptibility to solidification cracking. In conclusion, even in small amounts, the impurity elements would influence the cracking tendency 25,26 …”

Section: Resultsmentioning

confidence: 90%

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Welding hot cracking characteristics and fracture mechanisms of nickel‐based alloy NS1402 under different constraint conditions

Zhou,

Huang,

Zheng

et al. 2023

Fatigue Fract Eng Mat Struct

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The influence of trace elements variation and constraint conditions on welding hot cracking was investigated to reveal the cracking characteristics of nickel‐based alloy NS1402. The fishbone tests and full restraint welding tests have been conducted to determine the cracking ratio. The mechanical and metallurgical fracture mechanisms were elaborated simultaneously. And the low‐melting point liquid membrane, which was a key metallurgical factor, was found in cracking fracture surface. Numerical simulations were conducted to illustrate the effects of transverse tensile stress/strain during welding processing. Results show that the liquid membranes were composed of FeNi, FeP, Co3Fe7, etc., indicating that liquid membranes were developed to higher melting point by Co3Fe7 eutectics due to the addition of Co, and it contributes to reducing cracking susceptibility of NS1402. The cracking was ductility‐dip cracking (DDC), which propagated in the forms of intergranular or transgranular fracture. Thus, adjusting element content and degrees of constraint could control the cracking tendency.

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Section: Resultsmentioning

confidence: 90%

“…In conclusion, even in small amounts, the impurity elements would influence the cracking tendency. 25,26…”

Section: Eds Scanning On Liquid Membrane Zonementioning

confidence: 99%

Welding hot cracking characteristics and fracture mechanisms of nickel‐based alloy NS1402 under different constraint conditions

Zhou,

Huang,

Zheng

et al. 2023

Fatigue Fract Eng Mat Struct

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“…As shown by small arrows in Figure 5 b, there is a small number of twin grain boundaries in the ISZ zone, accounting for about 7.7% of the grain boundaries, while only very small amounts of secondary precipitates are observed at the grain boundaries of the joint. There is competition between non-metallic precipitates and twin boundaries for the initiation of fatigue cracks [ 42 ]. Previous studies have found that the interaction between dislocations and grain boundaries has an important effect on grain boundary crack initiation.…”

Section: Resultsmentioning

confidence: 99%

Transient Liquid Phase Diffusion Bonding of Ni3Al Superalloy with Low-Boron Nickel-Base Powder Interlayer

Wen

Liu

et al. 2023

Materials

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As a technology for micro-deformed solid-phase connection, transient liquid phase (TLP) diffusion bonding plays a key role in the manufacture of heating components of aero engines. However, the harmful brittle phase and high hardness limit the application of TLP diffusion bonding in nickel-based superalloys. In this paper, a new strategy in which a low-boron and high-titanium interlayer can restrain the brittle phase and reduce the hardness of the TLP-diffusion-bonded joint is proposed. With this strategy, the Ni3Al joint can achieve a high strength of 860.84 ± 26.9 MPa under conditions of 1250 °C, 6 h and 5 MPa. The microhardness results show that the average microhardness of the joint area is 420.33 ± 3.15 HV and is only 4.3% higher than that of the Ni3Al base material, which proves that this strategy can effectively inhibit the formation of the harmful brittle phase in the joint area. The results of EBSD show that 7.7% of the twin boundaries exist in the isothermal solidification zone, and only small amounts of secondary precipitates are observed at the grain boundaries in the joint, which indicates that twin boundaries may play a dominant role in crack initiation. This study provides a feasible avenue to suppress the brittle phase in TLP-diffusion-bonded joints.

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“…When metallurgical defects are present, a competitive mechanism occurs between crack nucleation near/at inclu-sions or near twin boundaries far from inclusions [35]. It has been demonstrated that inclusions trigger the development of intense slip localization and consequently form cracks in the vicinity near and parallel to twin boundaries [50]. Identifying the microstructural effect on slip localization is difficult because nanometer resolution and large fields of view are necessary to capture slip localization variability as a function of the microstructure.…”

Section: Slip Localization In a Nickel-based Superalloy Inconel 718mentioning

confidence: 99%

High-Throughput High-Resolution Digital Image Correlation Measurements by Multi-Beam SEM Imaging

et al. 2023

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Background Recent improvements in spatial resolution and measurement sensitivity for high-resolution digital image correlation (HR-DIC) now provide an avenue for the quantitative measurement of deformation events and capturing the physical nature of deformation mechanisms. However, HR-DIC measurements require significant time due to scanning electron image acquisition; such a limitation prevents the widespread use of HR-DIC for material characterization. Objective Apply a novel SEM acquisition technology to enhance HR-DIC measurements for high throughput applications. Methods Multi-beam SEM technology is employed to image an entire gauge length at once at high resolution and at nearly a hundredfold acceleration of typical HR-DIC image acquisition, even when automated stage movement and image acquisition are employed. These images were fed into a discontinuity-tolerant HR-DIC software to determine slip localization induced by non-metallic inclusions and grain structure. Results Slip localization was able to be analyzed to an unprecedented level, with over 210,000 slip bands able to be investigated, with the most intense slip localizing near and parallel to twin boundaries and in the vicinity of non-metallic inclusion clusters. Additionally, secondary slip activation and grain boundary shearing by intense dislocation pileups are observed to reduce slip amplitude near and parallel to twin boundaries. Conclusions By performing HR-DIC in conjunction with a multi-beam SEM, high-throughput measurements of large fieldof-view, high-resolution images were able to be performed in a timely manner. These measurements provided an immense number of slip events for statistical analysis to be performed on to relate to microstructural features.

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Twin boundary fatigue crack nucleation in a polycrystalline Nickel superalloy containing non-metallic inclusions

Cited by 22 publications

References 45 publications

Welding hot cracking characteristics and fracture mechanisms of nickel‐based alloy NS1402 under different constraint conditions

Welding hot cracking characteristics and fracture mechanisms of nickel‐based alloy NS1402 under different constraint conditions

Transient Liquid Phase Diffusion Bonding of Ni3Al Superalloy with Low-Boron Nickel-Base Powder Interlayer

High-Throughput High-Resolution Digital Image Correlation Measurements by Multi-Beam SEM Imaging

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