Plastic deformation inhomogeneity in a single crystal nickel-base superalloy

Wu, Xin; Zhang, J.H; Liu, J.L; Jin, Tao; Xu, Yujie; Hu, Z.Q.

doi:10.1016/s0921-5093(01)01666-5

Cited by 15 publications

(7 citation statements)

References 2 publications

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“…Hence, DSA in combination with highly localized deformation bands is one reason for the serrated yielding behavior of the

direction. This is in line with previous research by Miner et al [ 14 ], who concluded that only one slip system is active during yielding for the

direction while multiple slip systems are active in the other directions. Due to symmetry reasons, the

direction has 4 slip systems with the same Schmid factor, while the

direction has 8 and the

direction has 6 equivalent slip systems.…”

Section: Resultssupporting

confidence: 93%

“…Research has showed that also interaction of planar slip bands can cause serrated yielding behavior [ 13 ]. Other literature [ 14 ] reported a plastic deformation inhomogeneity in different crystallographic directions for the DD8 single-crystal superalloy. In compression at 550 °C, the

direction showed a stronger inhomogeneity compared to

and

.…”

Section: Introductionmentioning

confidence: 96%

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Crystallographic Orientation Influence on the Serrated Yielding Behavior of a Single-Crystal Superalloy

Segersäll

Moverare

2013

Materials

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Since Ni-based single-crystal superalloys are anisotropic materials, their behavior in different crystal orientations is of great interest. In this study, the yielding behavior in both tension and compression for 〈001〉, 〈011〉 and 〈111〉 oriented materials at 500 °C has been investigated. The 〈011〉 direction showed a serrated yielding behavior, a great tension/compression asymmetry in yield strength and visible deformation bands. However, the 〈001〉 and 〈111〉 directions showed a more homogeneous yielding, less tension/compression asymmetry in yield strength and no deformation bands. Microstructure investigations showed that the serrated yielding behavior of the 〈011〉 direction can be attributed to the appearance of dynamic strain aging (DSA) and that only one slip system is active in this direction during plastic deformation.

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“…Hence, DSA in combination with highly localized deformation bands is one reason for the serrated yielding behavior of the

direction. This is in line with previous research by Miner et al [ 14 ], who concluded that only one slip system is active during yielding for the

direction while multiple slip systems are active in the other directions. Due to symmetry reasons, the

direction has 4 slip systems with the same Schmid factor, while the

direction has 8 and the

direction has 6 equivalent slip systems.…”

Section: Resultssupporting

confidence: 93%

direction showed a stronger inhomogeneity compared to

and

.…”

Section: Introductionmentioning

confidence: 96%

Crystallographic Orientation Influence on the Serrated Yielding Behavior of a Single-Crystal Superalloy

Segersäll

Moverare

2013

Materials

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“…With regard to unloading process, the slope of unloading curve is related with according to (13). And it can be found that all the unloading curves of FEM results are parallel to that of experimental data (Figure 15), indicating that the difference of unloading process is attributed to the error of ℎ in loading process and the selection of in FEM model is reasonable.…”

Section: Verification Of Elastic-plastic Modelmentioning

confidence: 73%

“…Yi et al [12] gave modeling process of tertiary creep of singlecrystal superalloy along different orientations. Wu et al [13] made extensile and compression tests at different temperatures on DD8 with various strain rates and the results indicate that the tendency to the plastic deformation inhomogeneity decreases in the order of [011], [001], and [111]. The previous investigations mainly concentrated on the fatigue life and creep properties with different orientations, while other fundamental performances of materials, such as hardness, Young's modulus, and yield stress are rarely focused on.…”

Section: Introductionmentioning

confidence: 99%

Micromechanical Behavior of Single‐Crystal Superalloy with Different Crystal Orientations by Microindentation

Dong

et al. 2015

Journal of Nanomaterials

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In order to investigate the anisotropic micromechanical properties of single-crystal nickel-based superalloy DD99 of four crystallographic orientations, (001), (215), (405), and (605), microindentation test (MIT) was conducted with different loads and loading velocities by a sharp Berkovich indenter. Some material parameters reflecting the micromechanical behavior of DD99, such as microhardnessH, Young’s modulusE, yield stressσy, strain hardening componentn, and tensile strengthσb, can be obtained from load-displacement relations.HandEof four different crystal planes evidently decrease with the increase ofh. The reduction ofHis due to dislocation hardening whileEis related to interplanar spacing and crystal variable.σyof (215) is the largest among four crystal planes, followed by (605), and (001) has the lowest value.nof (215) is the lowest, followed by (605), and that of (001) is the largest. Subsequently, a simplified elastic-plastic material model was employed for 3D microindentation simulation of DD99 with various crystal orientations. The simulation results agreed well with experimental, which confirmed the accuracy of the simplified material model.

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“…Another difference between the crystal orientations is their behaviour during plastic deformation. Sometimes a serrated yielding is observed for superalloys, see for example [35][36][37][38]. In the literature it is common to find that the 011 direction shows a serrated yielding, while the 001 and 111 directions show a more homogeneous yielding behaviour.…”

Section: Yielding Behaviourmentioning

confidence: 99%

On Thermomechanical Fatigue of Single-Crystal Superalloys

Segersäll¹

2014

Linköping Studies in Science and Technology. Dissertations

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Thesis cover: Design by Maria J. SegersällPrinted by: LiU-Tryck, Linköping, Sweden, 2014 ISBN 978-91-7519-211-6 ISSN 0345-7524 Distributed by: Division of Engineering Materials, Department of Management and Engineering Linköping University SE-58183, Linköping, Sweden © 2014 Mikael SegersällThis document was prepared with L A T E X, October 17, 2014 AbstractThanks to their excellent mechanical and chemical properties at temperatures up to 1000°C, nickel-based superalloys are used in critical components in high-temperature applications such as gas turbines and aero engines. One of the most critical components in a gas turbine is the turbine blade, and to improve the creep and fatigue properties of this component, it is sometimes cast in single-crystal form rather than in the more conventional polycrystalline form. Gas turbines are most commonly used for power generation and the turbine efficiency is highly dependent on the performance of the superalloys.Today, many gas turbines are used as a complement for renewable energy sources, for example when the wind is not blowing or when the sun is not shining, which means that the turbine runs differently compared to earlier, when it ran for longer time periods with a lower number of start-ups and shutdowns. This new way of running the turbine, with an increased number of start-ups and shut-downs, results in new conditions for critical components, and one way to simulate these conditions is to perform thermomechanical fatigue (TMF) testing in the laboratory. During TMF, both mechanical strain and temperature are cycled at the same time, and one fatigue cycle corresponds to the conditions experienced by the turbine blade during one start-up and shut-down of the turbine engine.In the work leading to this PhD thesis, TMF testing of single-crystal superalloys was first performed in the laboratory and this was then followed microstructure investigations to study the occurring deformation and damage mechanisms. Specimens with different crystallographic directions have been tested in order to investigate the anisotropic behaviour shown by these materials. Results show a significant orientation dependence during TMF in which specimens with a low elastic stiffness perform better. However, it is also shown that specimens with a higher number of active slip systems perform better during TMF compared to specimens with less active slip sysiii tems. This is because a higher number of active slip systems results in a more widespread deformation and seems to be beneficial for the TMF life. Further, microscopy shows that the deformation during TMF is localised to several deformation bands and that different deformation and damage mechanisms prevail according to in which crystal orientation the material is loaded. Deformation twinning is shown to be a major deformation mechanism during TMF and the interception of twins seems to trigger recrystallization. This is certainly negative for the mechanical properties of single-crystal superalloys since no grain boundary strengthening elemen...

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Plastic deformation inhomogeneity in a single crystal nickel-base superalloy

Cited by 15 publications

References 2 publications

Crystallographic Orientation Influence on the Serrated Yielding Behavior of a Single-Crystal Superalloy

Crystallographic Orientation Influence on the Serrated Yielding Behavior of a Single-Crystal Superalloy

Micromechanical Behavior of Single‐Crystal Superalloy with Different Crystal Orientations by Microindentation

On Thermomechanical Fatigue of Single-Crystal Superalloys

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