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Title: Designing Brittle Fracture Specimens to Investigate Environmentally Assisted Crack Growth.


Abstract not provided.

; ; ; ; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the NOMAD 2016 Poster Session.
Country of Publication:
United States

Citation Formats

Negus, Michaela, Aduloju, S., Gu, W., Grutzik, Scott Joseph, Reedy, Earl David ,, Emery, John M, and Truster, T. Designing Brittle Fracture Specimens to Investigate Environmentally Assisted Crack Growth.. United States: N. p., 2016. Web.
Negus, Michaela, Aduloju, S., Gu, W., Grutzik, Scott Joseph, Reedy, Earl David ,, Emery, John M, & Truster, T. Designing Brittle Fracture Specimens to Investigate Environmentally Assisted Crack Growth.. United States.
Negus, Michaela, Aduloju, S., Gu, W., Grutzik, Scott Joseph, Reedy, Earl David ,, Emery, John M, and Truster, T. 2016. "Designing Brittle Fracture Specimens to Investigate Environmentally Assisted Crack Growth.". United States. doi:.
title = {Designing Brittle Fracture Specimens to Investigate Environmentally Assisted Crack Growth.},
author = {Negus, Michaela and Aduloju, S. and Gu, W. and Grutzik, Scott Joseph and Reedy, Earl David , and Emery, John M and Truster, T.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 7

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  • Analytical models are being used to predict intergranular stress corrosion crack growth (IGSCC) in austenitic components. An important feature of these models is the ability to separately consider the effect of key material and water chemistry parameters, such as sensitization, conductivity, and electrochemical potential (ECP). The validation of these models has been based primarily on comparison with small specimen data, such as compact tension tests under sustained loading. Before the models can be used to predict crack growth in power plant piping, it is necessary to benchmark the analysis with experimental data on stress corrosion cracks in piping welds withmore » loading similar to that expected in an operating plant. This paper describes the results from testing a 10-inch diameter stainless steel pipe having real and simulated cracks in the weld heat affected zone (HAZ).« less
  • Brittle fracture is known to occur in ductile metals in special gaseous environments. Often, these gases form thin solid films on the metal. Computer simulations were used to study the propagation of cracks coated with thin elastically hard films in a ductile two-dimensional material. It was found that under certain conditions secondary crack nucleation occurred in the simulations and brittle fracture was observed. The dynamics of the crack nucleation and the detailed spatial distribution of local forces were examined. A model has been developed for this new mode of crack nucleation and brittle fracture. The role of the elastically hardmore » film in suppressing dislocation generation and in initiating the secondary crack is discussed. This mode of initiating brittle fracture is entirely different from usual models for gaseous embrittlement.« less
  • Surface cracked tension specimens of ASTM A515, Grade B steel plate were tested to failure in the ductile-to-brittle transition region. Two different specimen configurations were used: one configuration was loaded in tension except for the natural bending resulting from the presence of the surface crack, the second configuration had an offset test section and was pin-loaded to provide a strong bending component in addition to the tension load. For each configuration, at least seven repeat tests were conducted at each of two temperatures. All specimens failed by cleavage and the critical J-integral, J{sub c}, was obtained using three-dimensional finite elementmore » analysis of the specimen. The FEM analysis was validated by comparison with experimental strain gage and displacement measurements taken during the tests. The results were compared with previous fracture toughness measurements on the same plate using 2T SE(B) specimens and surface cracked bend SC(B) specimens. The present results exhibited the expected elevation in fracture toughness and downward shift in the transition temperature compared to the highly constrained, deeply cracked SE(B) specimens. The master curve approach was used to characterize the transition curves for each specimen geometry and the shift in the transition temperature was characterized by the associated reference temperature.« less
  • The effect of temperature on the anodic dissolution and film repair on pressure vessel steel in deaerated environments was measured by using CERT under controlled potential. The effect of dissolved sulfide was taken into account in this study. The results show that temperature has little effect on the kinetics of anodic processes between 80 and 290{degrees}C except that the amount of sulfide required to trigger high dissolution rates decreases when the temperature decreases. In the range 200-290{degrees}C, these results are consistent with the current model which assumes that corrosion fatigue crack growth rates on low alloy steel in PWR watermore » are controlled by the film repair kinetics at the crack tip. The agreement is questionable at lower temperatures. The CERT under controlled potential also suggested that plastic deformation cannot account for the effect of sulfur on the anodic processes at crack tip in EAC conditions. Thus, besides anodic dissolution, mechanical decohesion is assumed to contribute to crack advance in EAC conditions.« less
  • The requirement of a sharp notch or precrack to cause environmental crack initiation of metastable {beta}-titanium alloys exposed to 0.6 M NaCl has been observed. The causal relationship has not been thoroughly examined, however. This paper seeks to explain the sharp notch requirement by examining notch acuity effects on a variety of parameters that affect HEAC susceptibility. These include the effects of a sharp notch on cation accumulation-hydrolysis-acidification, potential drop in solution and resulting hydrogen production, and localization of dynamic strain. It is shown that solution resistance down a sharp crack is two orders of magnitude larger for a fatiguemore » precracked compact tension specimen than for a smooth bar. The potential drop down a sharp crack is severe enough to enable hydrogen production even when the applied potential is more positive than the reversible potential for hydrogen production. It`s also shown that a fatigue precrack results in an acidified crack tip chemistry (approximately pH 1) which is deleterious to HEAC resistance. The effects of a sharp notch on the interplay of mechanics, film rupture and hydrogen uptake are also examined. It is shown that the slip behavior at a sharp crack tip promotes localized film rupture and localized hydrogen uptake. Localization of hydrogen uptake may be critical for HEAC susceptibility in light of the large hydrogen concentration required to cause crack initiation (ca. 1,000 wt. ppm) and the lack of significant hydrogen uptake on filmed surfaces.« less