The reliability of the fracture mechanics approach to environmentally assisted cracking: 1. Uniqueness of the v(K)-curve

Toribio, J.; Kharin, V.

doi:10.1016/s0261-3069(97)00092-7

Cited by 14 publications

(15 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[9] to obtain predictions of the normalized crack velocity, _ a= _ a Ã , as a function of applied K and K rate, dK/dt (dd=dt), requires that we evaluate Eq. [6] to obtainĥ gb as a function of K. We need also to evaluate Eq. [16] to obtain h gbs , which is a function of A Ã S , which is in turn a function of dd=dt and _ a= _ a Ã (Eq.…”

Section: Graphical Methods For Semiquantitative Analysis Of Predictmentioning

confidence: 99%

“…The crack velocity accelerates from an initially low crack growth rate and approaches steady state after a transient period of crack growth that is dependent on the initial applied K and environment chemistry. Toribio and Kharin [6] collected from the literature numerous experimental examples where K th and _ aðKÞ are not unique but depend on geometry, preloading conditions, and the kinematics of initial loading for constant K tests, such as those of Hudak and Wei, and loading rate in a constant loading rate test. These kinematic effects on K th and _ aðKÞ are the focus of this modeling effort.…”

Section: MM Hall Jrmentioning

confidence: 99%

“…The critical grain boundary occupancŷ h gb is given by Eq. [6] and, using Eq. [3], h gbs is evaluated at the crack tip surface, r = 0:…”

Section: F K-controlled Initiation Hydrogen-diffusion-limited Heac mentioning

confidence: 99%

See 2 more Smart Citations

Effect of Variable Stress Intensity Factor on Hydrogen Environment Assisted Cracking

Hall

2010

Metall Mater Trans A

View full text Add to dashboard Cite

Fitness-for-service evaluations of engineered components that are subject to environment assisted cracking (EAC) often require analyses of potentially large crack extensions through regions of variable stress intensity. However, there are few EAC data and models that directly address the effects of variable stress intensity factor on EAC crack growth. The model developed here is used to evaluate stress corrosion cracking (SCC) data that were obtained on a highstrength beta-titanium alloy under conditions of variable crack mouth opening displacement (CMOD) rate. SCC of this Ti alloy in ambient temperature, near-neutral NaCl aqueous solution is thought to be due to hydrogen environment assisted cracking (HEAC). As the model equations developed here do not admit to a closed form solution for crack velocity as a function of applied stress intensity factor, K, a semiquantitative graphical solution is used to rationalize the crack growth data. The analyses support a previous suggestion that the observed crack growth rate behavior can be attributed to the effect of crack tip strain rate on rates of mechanical disruption and repair of an otherwise protective crack tip oxide film. Model elements introduced here to HEAC modeling include (1) an expression relating corrosion-active surface area to crack tip strain rate and repassivation rate, (2) an expression relating the critical grain boundary hydrogen to the applied stress intensity factor, and (3) an expression relating CTSR to both applied and crack advance strain rate components. Intergranular crack advance is modeled assuming diffusive segregation of corrosion-generated hydrogen to grain boundary trap sites causing embrittlement of the fracture process zone (FPZ). The model equations developed here provide a quantitative basis for understanding the physical significance of K-variation effects and, with additional development, will provide an engineering tool for analysis of crack growth in a variable K field.

show abstract

Section: Graphical Methods For Semiquantitative Analysis Of Predictmentioning

confidence: 99%

Section: MM Hall Jrmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Variable Stress Intensity Factor on Hydrogen Environment Assisted Cracking

Hall

2010

Metall Mater Trans A

View full text Add to dashboard Cite

show abstract

“…The results presented in [1] show that the same values of the stress intensity factor does not always result in equal crack-growth rates if all other characteristics of material-environment couples are identical. The observed deviations cannot be related to imperfect testing and are systematic, unlike the obvious statistical spread in the experimental data.…”

mentioning

confidence: 92%

“…The reliability of the fracture-mechanics approach to EAC in engineering design is surveyed in [1], where one can find a rich collection of experimental examples of the ambiguous behavior of the v (K)-curve and the threshold Kth. Although these items are supposed to depend solely on the material and environments, they are notably sensitive to the influence of many test and service factors, namely (cf.…”

mentioning

confidence: 99%

Fracture mechanics approach to hydrogen assisted cracking: Analysis of theK-dominance condition

Toribio¹,

Kharin²

1999

Mater Sci

Self Cite

View full text Add to dashboard Cite

We summarize the achievements of a major research line at the Department of Materials Science of the University of La Corufia (Spain) in the field of environmentally-assisted cracking in general and hydrogen degradation in particular, We analyze the meaning and significance of the fracture-mechanics approach to hydrogen-assisted cracking and study the problem of K-dominance not only over the mechanical aspects of the phenomenon but also over the environmental (physicochemical) factors affecting the entire coupled process of hydrogenation and failure. Two key factors capable of violating the unambiguous behavior of the kinetic diagram of crack growth v = v (K) are discussed: the role of the far stressstrain field (i.e., the stress-strain field which is not K-dominated) and the effect of the history of hydrogenation and crack growth. For this purpose, we consider the stress-strain-assisted diffusion of hydrogen regarded as a rate-controlling factor of hydrogen-assisted cracking under sustained or quasistatic loads. It is shown that the far field produces a minor effect on the near-tip diffusion of hydrogen. This can only increase the spread in crack growth rates in the near-threshold part of the v (K)-curve. As far as the influence of the history is concerned, we discovered that the processes of hydrogenation and crack growth are coupled, each of them affects the other, and, hence, the kinetic diagram of crack growth v = v (K) is not one-to-one as should be for an intrinsic property of the material. However, there exists a special mode of steady-state crack growth when hydrogen-assisted cracking becomes a K-dominated process and the corresponding plot of the steady-state rate v as a function of K becomes unambiguous (as a characteristic curve of the material) and, thus, can be used in the engineering practice for a more conservative evaluation of the crack-growth resistance of materials and structural integrity,

show abstract

Fracture Mechanics Approach to Stress Corrosion Cracking of Pipeline Steels: When Hydrogen Is the Circumstance

Toribio

2011

Integrity of Pipelines Transporting Hydrocarbons

View full text Add to dashboard Cite

The reliability of the fracture mechanics approach to environmentally assisted cracking: 1. Uniqueness of the v(K)-curve

Cited by 14 publications

References 30 publications

Effect of Variable Stress Intensity Factor on Hydrogen Environment Assisted Cracking

Effect of Variable Stress Intensity Factor on Hydrogen Environment Assisted Cracking

Fracture mechanics approach to hydrogen assisted cracking: Analysis of theK-dominance condition

Fracture Mechanics Approach to Stress Corrosion Cracking of Pipeline Steels: When Hydrogen Is the Circumstance

Contact Info

Product

Resources

About