Fatigue crack growth behavior in inconel 706 at 297 K and 4.2 K

Liaw, Peter K.; Logsdon, W. A.

doi:10.1016/0001-6160(88)90241-6

Cited by 14 publications

(6 citation statements)

References 44 publications

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“…These results are consistent with the studies Liaw and Logsdon in Inconel 706 between 297 K and 4.2 K. 20) Only at rates exceeding of the level da/dNϭ10 Ϫ6 mm/cycle, the first isolated favorably oriented cleavage facets appear, limited by grain size. When the FCG rates are above da/dNϭ 10 Ϫ5 mm/cycle also the appearance of brittle jumps especially in the fine grains steels was observed.…”

Section: Fractographysupporting

confidence: 92%

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Effect of Grain Size on the Fatigue Crack Growth in Steels at Temperatures 295 and 77 K

Rosenberg

2003

ISIJ International

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Experiments were conducted on the same materials, which were used in the previous study, 15) where fatigue strength in smooth and notched specimens, and the growth of so-called short fatigue cracks were investigated. In this work are minutely presented only the results conducted on a commercially produced low-carbon steel (marked steel 1) and two HSLA steels (steel 2 and 3). The steels marked 1a and 1b exhibited coarse-grain microstructures produced by heat treating of steel 1.Single edge notch, three point bend specimens machined perpendicularly and parallelly to the rolling direction had a ISIJ International, Vol. 43 (2003) Fatigue crack growth (FCG) and threshold stress intensity in low carbon and HSLA steels with remarkably different ferrite grain sizes (d f ) at room temperature and temperature of liquid nitrogen were investigated. The FCG rates were found to decrease with decreasing temperature for all investigated microstructural states and the influence of temperature decrease was the most significant in coarse grain microstructures. The threshold values of the stress intensity factor, (DK th ), below which cracks do not propagate, decreased by between 29.1 % (d f ϭ2.7 mm) and 49.3 % (d f ϭ88.4 mm) when specimens were tested at the cryogenic temperature.A general relationship between the FCG rate, the effects of grain boundary blocking on the plastic zone size and/or the crack-tip opening displacement and the effect of changing temperature, is discussed. Furthermore, the concept of a functional relation between tensile and fatigue data at cryogenic temperatures was also investigated. It was shown that the ratio of DK th at 77 K to DK th at 295 K is proportional to the second root of the ratio of the tensile strength values at these temperatures i.e. DK th 77 K /DK th 295K £ (s u 77 K /s u 295 K ) 1/2 .

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Section: Fractographysupporting

confidence: 92%

“…10,19,20)). Crystallographic fracture facets and in restricted measure failure on the boundaries of grains in the near-threshold region for all structure states and ductile striations (except for steel 3) at the highest FCG rates were always visible.…”

Section: Fractographymentioning

confidence: 99%

Effect of Grain Size on the Fatigue Crack Growth in Steels at Temperatures 295 and 77 K

Rosenberg

2003

ISIJ International

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“…This difference in the fatigue-crack-growth rate at different R ratios can be attributed to the crack-closure effect. [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] At the low R ratio, the effective stress-intensity range experienced by the alloy at the fatigue-crack tip will decrease due to crack-closure effects, and, consequently, slower crackgrowth rates are observed at the low R ratio than at the high R ratio. However, the monotonic crack-tip openings are large at the high R ratio, and, thus, the crack-closure effects are virtually eliminated, although, in this case, the change in R ratio did not cause any alteration in failure mechanisms.…”

Section: Influence Of Load Ratio and Temperature On Crackgrowth Bementioning

confidence: 99%

“…It has been suggested that the fatigue-crack-growth behavior of super-alloys is closely related to the temperature, cyclic frequency, hold time, loading ratio, initial microstructure, and environment. [15][16][17][18][19][20][21][22][23] In the studies carried out by Byrne et al on a wrought, nickel-based Waspaloy alloy, [16] it was noted that the general effect of an increase in temperature was an increase in the fatigue-crack-growth rates by a factor of about 3 in the 550°C to 700°C temperature range. Gayda et al [17] observed a systematic increase in the crackgrowth rate per cycle with test frequency in the 0.02 to 5 Hz range for a RENÉ* 95 alloy fatigued in air at 650°C.…”

Section: Introductionmentioning

confidence: 99%

“…Liaw and Logsdon, [19] as well as Bartosiewicz et al, [20] showed that the fatigue-crack-growth rates of superalloys in the threshold region increased with increasing R ratio (where R ϭ min / max and min and max are the applied minimum and maximum stresses, respectively). In addition, it was observed that the influence of the R ratio on fatigue-crack-growth was much smaller in the Paris region than in the threshold region.…”

Section: Introductionmentioning

confidence: 99%

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The low-cycle fatigue and fatigue-crack-growth behavior of HAYNES® HR-120 alloy

Chen

Liaw

McDaniels

et al. 2003

Metall Mater Trans A

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The low-cycle fatigue and fatigue-crack-growth behavior of the HAYNES HR-120 alloy was investigated over the temperature range of 24°C to 980°C in laboratory air. The result showed that increasing the temperature usually led to a substantial decrease in the low-cycle fatigue life. The reduction of fatigue life could be attributed to oxidation and dynamic strain-aging (DSA) processes. The strain vs fatigue-life data obtained at different temperatures were analyzed. It was also found that the fatigue-crack-growth rate per cycle generally increased with increasing temperature and R ratio (R ϭ min / max , where min and max are the applied minimum and maximum stresses, respectively). The relationship between the stress-intensity-factor range and fatigue-crack-growth rate was determined. Scanning-electron-microscopy (SEM) examinations of the fracture surfaces revealed that the fatigue cracks initiated and propagated predominantly in a transgranular mode.

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Growth of Small Fatigue Cracks in Incoloy-908

Mei

Krenn

Morris

1994

Advances in Cryogenic Engineering Materials

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ACKNOWLEDGMENTsuming that a crack is present and designing to an extension of the Paris Law at 4.2K. sample fatigue limit is reasonably safe, and even greater design safety can be ensured by as small-grained material are very high. Hence, a design that maintains loads below the smooth However, the values of Ao taht are required to raise AK to near AK[h for small cracks in a ber, and, certainly, is not ·a reliable design parameter value, when short cracks are present.The results suggest that the threshold stress intensity, AKG], is not a very meaningful num tigue endurance limit that can be determined at 4.2 K with ground and polished specimens. tion (2) is satished, a small crack does not grow when the applied stress is less than the fa tests at 4.2 K, and is bounded by tests at constant AKmax. If neither condidon (1) nor condi crack; its growth rate obeys the constitutive relations determined from the long-crack growth size or (2) the crack tip plastic zone is larger than grain size, the crack behaves as a long tion at 4.2 K. When either (1) the size of a crack is larger than several times the average gain 908, the experimental results suggest a method for estimating the rate of small crack propaga N0 matter what mechanisms control the anomalous growth of small crack in Incoloy elsewhere.10 OCR Output are summarized here; a complete description of our research on this subject will be published and (3) direct observations of the propagation of very small surface cracks. The main results long crack growth rates under closure-free conditions to simulate short crack propagation, tensity (Kmax), the method proposed by Herman, Hertzberg, and Jaccardg to determine the tests at constant load-ratio (R), (2) long-crack growth tests at constant maximum stress in We measured and compared fatigue crack growth rates in (1) conventional long-crack growthThe approach taken in this study resembles that in our previous work on A286 steel. isotropic continuum is no longer held. vant microstructural dimensions, the assumption that the crack grows in a homogeneous, fracture mechanics becomes invalid. (3) When the crack size is small compared to the rele local plasticity, the small-scale yield assumption that underlies the application of linear elastic when the crack is very short. (2) When the crack size becomes comparable to the scale of Crack closure that lowers the driving force for lon g-crack propagation is absent or reduced nisms for the anomalous growth of small cracks are described in recent reviews.5'7 (1) may propagate at cyclic stress intensities below the long-crack threshold. Several mecha cracks often grow faster than long cracks at the same nominal cyclic stress intensities, and tive relations that govem long cracks become invalid when the crack size is small; small Recent results on the propagation of surface fatigue cracks2'4 show that the constitu timating small crack propagation at 4.2 K. gation at room temperature and 77 K, and use the results to propose a feasible method for es tigue crack propagation tests at ...

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Fatigue crack growth behavior in inconel 706 at 297 K and 4.2 K

Cited by 14 publications

References 44 publications

Effect of Grain Size on the Fatigue Crack Growth in Steels at Temperatures 295 and 77 K

Effect of Grain Size on the Fatigue Crack Growth in Steels at Temperatures 295 and 77 K

The low-cycle fatigue and fatigue-crack-growth behavior of HAYNES® HR-120 alloy

Growth of Small Fatigue Cracks in Incoloy-908

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