Crystallographic fatigue crack initiation in nickel-based superalloy René 88DT at elevated temperature

Miao, Jr‐Ming; Pollock, Tresa M.; Jones, J. W.

doi:10.1016/j.actamat.2009.08.022

Cited by 274 publications

(128 citation statements)

References 18 publications

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“…As shown in Table 3, the active slip systems for crack initiation in the twincontaining grains are associated with the high resolved shear stress indicated by high SF and parallel to TB, which is consistent with Miao's study on polycrystalline nickel-based superalloy Rene´ 88DT [15]. However, it seems that activation of the primary slip systems which are parallel to the TB in the matrix and the twin is a more important prerequisite for TB crack initiation, because it is found that the active slip systems associated with crack initiation are not always experiencing the highest resolved shear stress as observed in crack CG C1a (PBB) in this study.…”

Section: Factors Controlling Crack Initiationsupporting

confidence: 77%

“…It is widely observed that cracks initiate at slip bands close to TBs and/or TBs in the polycrystalline Ni-based superalloys due to their high slip planarity [11,15,21]. In this study, crack initiation predominantly occurs at TBs and occasionally occurs at slip bands in the relatively large grain in the LSHR alloy due to the relatively high volume fraction of TBs caused by the low stacking fault energy.…”

Section: Factors Controlling Crack Initiationmentioning

confidence: 85%

“…It is reported that slip bands parallel to a TB can form easily at the matrix and twin adjacent to the TB and concentrate at the TB due to the high elastic incompatibility stress which is induced to meet the requirement of the discontinuity of stress and displacement across the TB [15,23]. The concentrated slip bands at the TB which are associated with strain localisation therefore lead to crack initiation at the TB or in the region adjacent to the TB.…”

Section: Factors Controlling Crack Initiationmentioning

confidence: 99%

“…It is generally accepted that fatigue crack initiation and short crack growth processes are important to optimise as they contribute to the majority of fatigue life of a turbine disc during service. This is due to the high overall component stresses which result in a relatively small extent of fatigue crack propagation prior to fast fracture and thereby limit the fatigue life dependency to the short crack growth regime [11][12][13][14][15]. As a result, a systematic assessment of crack initiation and subsequent short crack growth behaviour is necessary at both lower and elevated temperatures in order to evaluate the intrinsic (without environmental attack) and extrinsic (with environmental attack) fatigue crack processes in appropriate microstructural variants of the LSHR alloy.…”

mentioning

confidence: 99%

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Effects of microstructures on fatigue crack initiation and short crack propagation at room temperature in an advanced disc superalloy

Jiang

Karpasitis

Gao

et al. 2015

Materials Science and Engineering: A

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Fatigue crack initiation and early short crack propagation behaviour in two microstructural variants of a recently developed Low Solvus, High Refractory (LSHR) disc superalloy at room temperature has been investigated by three-point bending with replication procedure.The results shows that fine gained (FG) LSHR possesses higher fatigue life due to its better crack initiation resistance, limited crack coalescence and comparable Stage I crack propagation resistance to the coarse grained (CG) LSHR, although its resistance to Stage II crack propagation is inferior. Twin boundary (TB) cracking in the relatively large grains dominates the crack initiation process along with occasional crack initiation due to slip band cracking. Activation of the primary slip systems parallel to the TB at matrix and twin and high resolved shear stress associated with high Schmid factor (SF) are required for TB crack initiation. Cracks preferentially propagate along slip bands associated with high SF slip systems after initiation. But cracks also propagate along slip bands associated with slip systems with lower SF if the inclination angle between the slip band ahead of the crack tip and the crack segment of the crack tip is small enough to enable a steady transition (or nondeflected growth) of cracks across the grain boundary.

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Section: Factors Controlling Crack Initiationsupporting

confidence: 77%

Section: Factors Controlling Crack Initiationmentioning

confidence: 85%

Section: Factors Controlling Crack Initiationmentioning

confidence: 99%

mentioning

confidence: 99%

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Effects of microstructures on fatigue crack initiation and short crack propagation at room temperature in an advanced disc superalloy

Jiang

Karpasitis

Gao

et al. 2015

Materials Science and Engineering: A

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“…The transition zone of these disks has a microstructure with variable grain size as a function of location. In coarse grain PM disk superalloys, fatigue failures can often initiate at grains which fail in a crystallographic manner due to concentrated slip [9,10]. These failing grains often appear to be relatively large with respect to the mean grain size for a given microstructure.…”

Section: Introductionmentioning

confidence: 99%

Fatigue Failure Modes of the Grain Size Transition Zone in a Dual Microstructure Disk

Gabb¹,

Kantzos²,

Palsa³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

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Mechanical property requirements vary with location in nickelbased superalloy disks. In order to maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored grain microstructures. In this study, fatigue failure modes of a grain size transition zone in a dual microstructure disk were evaluated. A specialized heat treatment method was applied to produce varying grain microstructure in the bore to rim portions of a powder metallurgy processed nickel-based superalloy disk. The transition in grain size was concentrated in a zone of the disk web, between the bore and rim. Specimens were extracted parallel and transversely across this transition zone, and multiple fatigue tests were performed at 427 °C and 704 °C. Grain size distributions were characterized in the specimens, and related to operative failure initiation modes. Mean fatigue life decreased with increasing maximum grain size, going out through the transition zone. The scatter in limited tests of replicates was comparable for failures of uniform gage specimens in all transition zone locations examined.

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Microstructure and Fatigue Behaviour in the Very High Cycle Fatigue Regime

Zimmermann¹,

Stöcker²,

Christ³

2010

Fatigue of Materials

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Over the last decade it was shown for a number of metals that failure occurs even beyond the classical fatigue limit. High frequency testing techniques make it possible to conduct fatigue tests up to 10 9 or even 10 11 number of cycles for various alloys ranging from aluminium to highstrength steels. Fatigue life in this regime is dominated by crack initiation. With the overall strain being in the purely elastic range, microstructural features acting as stress raisers lead to localized and inhomogeneously distributed irreversible deformation. Hence microstructural discontinuities become the leading features controlling fatigue life at very high number of cycles. The given survey will focus on dislocation arrangement, grain orientation, grain size and surface roughness and their implications on the VHCF behaviour for selected non-ferrous and virtually defect free metals, thus providing a sound basis for a detailed understanding of the relevant deformation and damage evolution mechanisms.

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Crystallographic fatigue crack initiation in nickel-based superalloy René 88DT at elevated temperature

Cited by 274 publications

References 18 publications

Effects of microstructures on fatigue crack initiation and short crack propagation at room temperature in an advanced disc superalloy

Effects of microstructures on fatigue crack initiation and short crack propagation at room temperature in an advanced disc superalloy

Fatigue Failure Modes of the Grain Size Transition Zone in a Dual Microstructure Disk

Microstructure and Fatigue Behaviour in the Very High Cycle Fatigue Regime

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