Fatigue Crack Growth Behavior of PWA 1484 Single Crystal Superalloy at Elevated Temperatures

Telesman, Jack; Ghosn, Louis J.

doi:10.1115/1.2816603

Cited by 73 publications

(57 citation statements)

References 7 publications

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“…Higher magnification disclosed an operative noncrystallographic failure mode, consisting of homogenously distributed rough features (Figs.7(b) and (c)), as reported by others [12] . No evidence of fatigue striations was found on the surface.…”

Section: Fatigue Fracture Modesupporting

confidence: 51%

“…This crack propagation is known to be octahedral crystallographic cracking (Stage I), which is the preferred crack propagation direction for low temperatures and high frequencies (> 3 Hz), for FCC nickel-based superalloys [11][12][13] . In our LCF tests, it was disclosed that the superalloy preferred the crystallographic cracking mode (Stage I) even under low frequencies ranging from 0.0305 Hz to 0.0439 Hz with a constant strain rate of 10 −3 s −1 .It should be noticed in Fig.6(c) that the failure facets exhibited a classical cleavage type failure with the associated river patterns, which is usually considered to be dependent on the normal stress component on the fracture facet [12] . The fractography supports the earlier observation that the stress normal to the slip plane can aid the failure process by preventing the crack closure while the resolved shear stress damages the slip planes ahead of the crack tip.…”

Section: Fatigue Fracture Modementioning

confidence: 99%

“…The cracking morphology has been found to depend on slip character in single crystals [11][12][13] : at lower temperatures and high frequencies, octahedral slip leads to Stage I (crystallographic) cracking; while at higher temperatures and low frequencies, 'wavy' slip leads to Stage II cracking perpendicular to the tensile axis. In some cases, Stage II initiation was followed by Stage I propagation and crystallographic facets on macroscopic fracture surfaces were observed [12] .…”

Section: Introductionmentioning

confidence: 98%

“…In some cases, Stage II initiation was followed by Stage I propagation and crystallographic facets on macroscopic fracture surfaces were observed [12] . The transition from crystallographic failure mode to Mode-I failure is not fully understood yet and quantitative parameters characterizing the influence of temperature, frequency, strain rate, stress condition and environment to clarify the mechanism are thus in need [1] .…”

Section: Introductionmentioning

confidence: 99%

“…The motivation behind these studies has been the high temperature application of precipitation hardened nickel-base superalloys in modern gas turbine aero-engines for their superior thermal, fatigue and creep properties compared to conventional cast alloys by removal of grain boundaries. The cyclic deformation behavior and low-cycle fatigue (LCF) failure of γ precipitation-hardened nickel base superalloys is strongly influenced by temperature [6][7][8][9][10] , frequency [5,[11][12][13] , strain rate [10] , crystallographic orientation [14,15] and environment [16] etc.…”

Section: Introductionmentioning

confidence: 99%

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Temperature Effect on Low-Cycle Fatigue Behavior of Nickel-Based Single Crystalline Superalloy

Shi

et al. 2008

Acta Mech. Solida Sin.

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The low-cycle fatigue (LCF) behavior of a nickel-based single crystal superalloy with [001] orientation was studied at an intermediate temperature of T0 • C and a higher temperature of T0 + 250 • C under a constant low strain rate of 10 −3 s −1 in ambient atmosphere. The superalloy exhibited cyclic tension-compression asymmetry which is dependent on the temperature and applied strain amplitude. Analysis on the fracture surfaces showed that the surface and subsurface casting micropores were the major crack initiation sites. Interior Ta-rich carbides were frequently observed in all specimens. Two distinct types of fracture were suggested by fractogaphy. One type was characterized by Mode-I cracking with a microscopically rough surface at T0 + 250 • C. Whereas the other type at lower temperature T0 • C favored either one or several of the octahedral {111} planes, in contrast to the normal Mode-I growth mode typically observed at low loading frequencies (several Hz). The failure mechanisms for two cracking modes are shearing of γ precipitates together with the matrix at T0 • C and cracking confined in the matrix and the γ/γ interface at T0 + 250 • C.KEY WORDS low cycle fatigue, single crystal, nickel-based superalloy

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Section: Fatigue Fracture Modesupporting

confidence: 51%

Section: Fatigue Fracture Modementioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Temperature Effect on Low-Cycle Fatigue Behavior of Nickel-Based Single Crystalline Superalloy

Shi

et al. 2008

Acta Mech. Solida Sin.

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The Effect of Crystal Orientation and Temperature on Fatigue Crack Growth of Ni‐Based Single Crystal Superalloy

Kagawa¹,

Mukai²

2012

Superalloys 2012

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Crack propagation tests were performed by using compact specimens made of Ni-based single crystal superalloy CMSX-4. Three types of specimens with different orientation were machined. The combinations of loading directions and machined notch directions wererespectively. Tests were performed at room temperature, 500°C, 700°C and 900°C for each orientation specimen.In all specimens tested at room temperature, cracks propagated along slip planes (stage-I), resulting fracture surfaces composed of slip planes. In specimens tested at elevated temperature, cracks propagated along the machined notch direction (stage-II) at the beginning of the tests. FEM calculations were conducted for evaluating the relations between mode I-III SIFs and crack length for specimen with inclined cracks.Methods for evaluating stage-I and stage-II crack propagation rates were proposed. Stage-I crack propagation rates were correlated within the range of factor of 4 using resolved shear stress intensity factor range which was calculated from shear stress on a slip plane parallel to the stage-I crack plane. Stage-II crack propagation rates of all specimens were correlated in the range of factor of 3 with energy release rate calculated using anisotropic elastic moduli. It was suggested that the difference in the elastic moduli caused by the difference between specimen orientation and tested temperature influenced primarily stage-II crack propagation rate.While stage-II cracking was predominant, stage-I fracture surfaces were initiated near side faces in some specimens, and the areas of the stage-I fracture surface tended to expand to the inner regions of the specimens with crack propagation. The transition from stage-II to stage-I was evaluated by using resolved shear stress intensity factor range under plane stress condition.

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A Proposal on Quantitative Treatment of Multiple Cracks Nucleating in Single Crystal Superalloys

Mukai

Kagawa

2012

Superalloys 2012

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Multiple crack propagation tests were performed at room temperature using four point bending specimens which contained nineteen cracks and were made of Ni-based single crystal superalloy CMSX-4. Two types of specimen orientations were machined. One's longitudinal direction was [010] and machined notch direction was [100], and another's was [010] and [101]. In each specimen, cracks propagated along {111} slip planes making ridges which inclined to the thickness direction. The cracks of the former also inclined to the longitudinal direction at an angle of 45°, while those of the latter propagated along the machined notch direction. To evaluate such crack propagation behavior, mode I -III stress intensity factors were calculated under three conditions. First, cracks were treated as single edge crack without considering crack interaction. Secondly, cracks were treated as multiple parallel edge cracks with same lengths. Third, cracks were treated as multiple parallel edge cracks with alternately different lengths. Since stage-I cracking was evaluated by resolved shear stress intensity factor range on {111} plane, resolved shear stress intensity factor was calculated from mode I -III stress intensity factors obtained by the above three conditions. Then, crack propagation simulations were performed. In case of the [010][101] orientation specimen, simulated crack propagation rates and behavior calculated under the third condition agreed well with the experimental ones. On the other hand, in case of the [010][100] specimen, those calculated by the first condition agreed better with the experiments than those simulated by the other conditions.

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Fatigue Crack Growth Behavior of PWA 1484 Single Crystal Superalloy at Elevated Temperatures

Cited by 73 publications

References 7 publications

Temperature Effect on Low-Cycle Fatigue Behavior of Nickel-Based Single Crystalline Superalloy

Temperature Effect on Low-Cycle Fatigue Behavior of Nickel-Based Single Crystalline Superalloy

The Effect of Crystal Orientation and Temperature on Fatigue Crack Growth of Ni‐Based Single Crystal Superalloy

A Proposal on Quantitative Treatment of Multiple Cracks Nucleating in Single Crystal Superalloys

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