Creep crack growth in udimet 700

Sadananda, K.; Shahinian, P.

doi:10.1007/bf02647174

Cited by 48 publications

(16 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Cyclic crack growth generally follows a transgranular path, while time-dependent crack growth due to stress-assisted grain boundary oxidation typically follows an intergranular path. [1][2][3][4][5][6][7][8][9][13][14][15][16][17][18] The transition from transgranular fracture to intergranular fracture depends on the temperature, load frequency, and hold time. In general, time-dependent crack growth under K-controlled conditions can be expressed as [21,23] da dt ¼ B o exp À Q RT K m with m>0 and K>K th ; ½4…”

mentioning

confidence: 99%

“…A number of investigations have successfully applied Eqs. [1] and [2] to treat concurrent cycle-dependent and time-dependent crack growth such as dwell fatigue in Ni-base superalloys. [2,[19][20][21]24] According to Eqs.…”

mentioning

confidence: 99%

“…[2,[19][20][21]24] According to Eqs. [1] through [4], time-dependent crack growth is dominant at long dwell times and low frequencies, provided that K max > K th , where K max is the maximum stress intensity factor in a loading cycle. In contrast, crack growth is entirely dominated by the cycle-dependent term, da/dN, at K max < K th , since da/dt = 0 in this regime.…”

mentioning

confidence: 99%

“…Creep crack growth by g.b. cavitation is observed in Ni-based alloys tested in vacuum or in an inert atmosphere, [1,17,19] but it is also observed in c¢-strengthened Ni-base alloys such as IN 738 and IN 939 tested in air. [24,25] For oxidation-induced crack growth and stress corrosion cracking, the degradation processes are the formation and growth of oxides along grain boundaries, and the corresponding crack paths are also predominantly intergranular.…”

mentioning

confidence: 99%

“…[24,25] For oxidation-induced crack growth and stress corrosion cracking, the degradation processes are the formation and growth of oxides along grain boundaries, and the corresponding crack paths are also predominantly intergranular. [1][2][3][4][5][6][7][8][9][13][14][15][16][17][18] For IN 718, the crack-tip oxidation processes during sustained load crack growth in air involved the formation of NiO and Cr 2 O 3 along grain boundaries. [4,5,7] The oxidation of grain boundary particles such as NbC during sustained load crack growth in air and in oxygen environment [26] or fatigue in air [27] was also reported by some investigators.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Time-Dependent Crack Growth Thresholds of Ni-Base Superalloys

Chan

2014

Metall Mater Trans A

View full text Add to dashboard Cite

A micromechanical model has been developed for predicting the time-dependent crack growth threshold and its variability by considering oxide formation or cavity formation ahead of an elastic crack subjected to a sustained load at a stress intensity factor, K, at elevated temperatures in air. It is demonstrated that stress relaxation associated with a volume-expansion process such as the formation of creep cavities or oxides with a positive transformation strain can induce residual stresses at the tip of the elastic crack. The near-tip residual stresses must be overcome by the external load, thereby instigating a growth threshold, K th , for the onset of time-dependent crack growth. This micromechanical framework provides the basis for developing appropriate predictive models for the time-dependent crack growth thresholds associated with several damage processes, including (1) oxidation-assisted intergranular crack growth, (2) K-controlled creep crack growth along an intergranular path, and (3) stress corrosion cracking. The micromechanical threshold models have been utilized to predict the time-dependent crack growth thresholds of a variety of Ni-base superalloys. The material parameters that contribute to the variability of the time-dependent crack growth thresholds have been identified and related to variations of mixed oxides or creep cavities formed near the crack tip. A size scale effect is also predicted for the transformation toughening phenomenon, which is largest at or below K th but diminishes at increasing K levels above the threshold. Finally, the micromechanical models are utilized to identify means for suppressing time-dependent crack growth in Ni-base alloys.

show abstract