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Sample records for suppress intergranular fracture

  1. Challenges in Continuum Modelling of Intergranular Fracture

    DEFF Research Database (Denmark)

    Coffman, Valerie; Sethna, James P.; Ingraffea, A. R.

    2011-01-01

    of grain boundaries, but also in crucial ways on edges, corners and triple junctions of even greater geometrical complexity. To address the first two challenges, we explore the physical underpinnings for creating functional forms to capture the hierarchical commensurability structure in the grain boundary......Intergranular fracture in polycrystals is often simulated by finite elements coupled to a cohesive zone model for the interfaces, requiring cohesive laws for grain boundaries as a function of their geometry. We discuss three challenges in understanding intergranular fracture in polycrystals. First...... properties. To address the last challenge, we demonstrate a method for atomistically extracting the fracture properties of geometrically complex local regions on the fly from within a finite element simulation....

  2. A fractal model for intergranular fractures in nanocrystals

    International Nuclear Information System (INIS)

    Lung, C.W.; Xiong, L.Y.; Zhou, X.Z.

    1993-09-01

    A fractal model for intergranular fractures in nanocrystals is proposed to explain the dependence of fracture toughness with grain size in this range of scale. Based on positron annihilation and internal friction experimental results, we point out that the assumption of a constant grain boundary thickness in previous models is too simplified to be true. (author). 7 refs, 6 figs

  3. Intergranular brittle fracture of a low alloy steel. Global and local approaches

    International Nuclear Information System (INIS)

    Kantidis, E.

    1993-08-01

    The intergranular brittle fracture of a low alloy steel (A533B.Cl1) is studied: an embrittlement heat treatment is used to develop two brittle 'states' that fail through an intergranular way at low temperatures. This mode of fracture leads to an important shift of the transition temperature (∼ 165 deg C) and a decrease in the fracture toughness. The local approach to fracture, developed for cleavage, is applied to the case of intergranular fracture. Modifications are proposed. The physical supports of these models are verified by biaxial (tension-torsion) tests. From the local approaches developed for intergranular fracture, the static and dynamic fracture toughness of the embrittled steel is predicted. The local approach applied to a structural steel, which presents mixed modes of fracture (cleavage and intergranular), showed that this mode of fracture seems to be controlled by intergranular loss of cohesion

  4. Fracture statistics of brittle materials with intergranular cracks

    International Nuclear Information System (INIS)

    Batdorf, S.B.

    1975-01-01

    When brittle materials are used for structural purposes, the initial design must take their relatively large dispersion in fracture stress properly into account. This is difficult when failure probabilities must be extremely low, because empirically based statistical theories of fracture, such as that of Weibull, cannot reliably predict the stresses corresponding to failure probabilities much lower than n -1 , where n is the number of specimens tested. Recently McClintock proposed a rational method of predicting the size distribution of intergranular cracks. The method assumed that large cracks are random aggregations of cracked grain boundaries. The present paper employs this method to find the size distribution of penny-shaped cracks, and also P(f), the probability of failure of a specimen of volume V subjected to a tensile stress sigma. The present paper is a pioneering effort, which should be applicable to ceramics and related materials

  5. Conversion of transgranular to intergranular fracture in NiCr steels

    Czech Academy of Sciences Publication Activity Database

    Hadraba, Hynek; Němec, O.; Dlouhý, Ivo

    2008-01-01

    Roč. 75, č. 12 (2008), s. 3677-3691 ISSN 0013-7944 R&D Projects: GA AV ČR IAA200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : intergranular fracture * cleavage * fracture toughness * fracture stress * micromechanics * micromechanism * fractal dimension Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 1.713, year: 2008

  6. Multi-scale modeling of inter-granular fracture in UO2

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Pritam [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Yongfeng [Idaho National Lab. (INL), Idaho Falls, ID (United States); Tonks, Michael R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Biner, S. Bulent [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    A hierarchical multi-scale approach is pursued in this work to investigate the influence of porosity, pore and grain size on the intergranular brittle fracture in UO2. In this approach, molecular dynamics simulations are performed to obtain the fracture properties for different grain boundary types. A phase-field model is then utilized to perform intergranular fracture simulations of representative microstructures with different porosities, pore and grain sizes. In these simulations the grain boundary fracture properties obtained from molecular dynamics simulations are used. The responses from the phase-field fracture simulations are then fitted with a stress-based brittle fracture model usable at the engineering scale. This approach encapsulates three different length and time scales, and allows the development of microstructurally informed engineering scale model from properties evaluated at the atomistic scale.

  7. Microstructural Modeling of Dynamic Intergranular and Transgranular Fracture Modes in Zircaloys

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, I. [North Carolina State Univ., Raleigh, NC (United States); Zikry, M.A. [North Carolina State Univ., Raleigh, NC (United States); Ziaei, S. [North Carolina State Univ., Raleigh, NC (United States)

    2017-04-01

    In this time period, we have continued to focus on (i) refining the thermo-mechanical fracture model for zirconium (Zr) alloys subjected to large deformations and high temperatures that accounts for the cracking of ZrH and ZrH2 hydrides, (ii) formulating a framework to account intergranular fracture due to iodine diffusion and pit formation in grain-boundaries (GBs). Our future objectives are focused on extending to a combined population of ZrH and ZrH2 populations and understanding how thermo-mechanical behavior affects hydride reorientation and cracking. We will also refine the intergranular failure mechanisms for grain boundaries with pits.

  8. Intergranular fracture in UO2: derivation of traction-separation law from atomistic simulations

    Energy Technology Data Exchange (ETDEWEB)

    Yongfeng Zhang; Paul C Millett; Michael R Tonks; Xian-Ming Bai; S Bulent Biner

    2013-10-01

    In this study, the intergranular fracture behavior of UO2 was studied by molecular dynamics simulations using the Basak potential. In addition, the constitutive traction-separation law was derived from atomistic data using the cohesive-zone model. In the simulations a bicrystal model with the (100) symmetric tilt E5 grain boundaries was utilized. Uniaxial tension along the grain boundary normal was applied to simulate Mode-I fracture. The fracture was observed to propagate along the grain boundary by micro-pore nucleation and coalescence, giving an overall intergranular fracture behavior. Phase transformations from the Fluorite to the Rutile and Scrutinyite phases were identified at the propagating crack tips. These new phases are metastable and they transformed back to the Fluorite phase at the wake of crack tips as the local stress concentration was relieved by complete cracking. Such transient behavior observed at atomistic scale was found to substantially increase the energy release rate for fracture. Insertion of Xe gas into the initial notch showed minor effect on the overall fracture behavior.

  9. The effect of thermal history on intergranular boron segregation and fracture morphology of substoichiometric Ni3Al

    International Nuclear Information System (INIS)

    Choudhury, A.; White, C.L.; Brooks, C.R.

    1986-01-01

    While it has attractive mechanical properties and good corrosion resistance, the usefulness of polycrystalline Ni 3 Al has been restricted because of its propensity for brittle intergranular fracture. While this intergranular brittleness can be aggravated by the intergranular segregation of certain impurities, particularly sulfur, the grain boundaries of Ni 3 Al are intrinsically brittle and Ni 3 Al will fail intergranularly in the absence of detectable impurity segregation. Addition of boron resulted in the fracture morphology changing from primarily intergranular to largely transgranular; and more importantly, the intergranular segregation of boron was conclusively demonstrated. The range of boron concentrations over which these beneficial effects are observed is well within the solubility limit, which has been estimated to be 1.5 at. % (4,5). Rice (6) developed a relationship between equilibrium intergranular segregation and grain boundary cohesion. According to this theory, the potential for intergranular embrittlement by a solute is related to the relative intensity of segregation of the solute to free surfaces as compared to segregation to grain boundaries. Rices theory allowed for the case of a solute segregating more strongly to grain boundaries than to free surfaces. If this difference is sufficiently large (approximately a factor of two), Rice's theory predicts an enhancement of grain boudary cohesion. White and coworkers (4,7) noted the rather unusual phenomenon of boron segregating much more strongly to grain boundaries of Ni 3 Al than to free surfaces, while sulfur (an embrittling impurity) was shown to exhibit the opposite effect

  10. Intergranular fracture stress and phosphorus grain boundary segregation of a Mn-Ni-Mo steel

    International Nuclear Information System (INIS)

    Naudin, C.; Frund, J.M.; Pineau, A.

    1999-01-01

    Nuclear Reactor Pressure Vessel (RPV) steel A508 class 3 which is a low alloyed steel is not usually sensitive to reversible temper embrittlement when properly heat treated. However heterogeneous zones may be present in particular near the inner side of the vessel. These zones result from the segregation of the alloying elements (C, Mn, Ni, Mo) and impurities (S, P) taking place during solidification of the material. They are called segregated zones (or ghost lines). They can reach 2 mm thick along the radius and 30 mm long through the circumferential direction. Their susceptibility to reversible temper embrittlement is mainly due to grain boundary phosphorus segregation triggering brittle intergranular fracture when the material is tested at low temperature. In this material like in other steels the influence of some other alloying elements (Mo, Mn...) is clearly significant and should also be taken into account. But phosphorus effect has proved to be predominant. The aim of the present study is therefore to find out a quantitative relationship between grain boundary phosphorus segregation and critical intergranular fracture stress. A synthetic steel with a chemical composition representative of an average segregated zone was prepared for the present study. A number of heat treatments were applied to reach different embrittlement conditions. Then brittle fracture properties were obtained by performing cryogenic fracture tests on notched tensile specimens while the corresponding grain boundary phosphorus levels were measured by Auger electron spectroscopy. Systematic fractographic observations were carried out. Moreover an attempt to determine the influence of temperature on the critical intergranular fracture stress was made

  11. Analysis of the intergranular fracture surface by the Fourier spectrum method

    Energy Technology Data Exchange (ETDEWEB)

    Hao Yao; Tian Jifeng; Wang Zhongguang (National Lab. for Fatigue and Fracture of Materials, Inst. of Metal Research, Academia Sinica, Shen Yang (China))

    1991-11-30

    A quantitative analysis of the fracture surface of a 1045 steel was undertaken in order to relate important microstructural features to brittle intergranular fractures in the steel. It was found that the character of the profile was not random but periodic. There is a direct correspondence between the Fourier spectrum of the profile and the microstructure features. Utilization of secondary-electron line scanning facilitated the analysis of the fracture surface in this case. The results of the analysis from both the profile and the scanning line showed that the first autocorrelation length is related to the average grain size and that the total power corresponds to the impact energy of the fracture. (orig.).

  12. Molecular-dynamics Simulation-based Cohesive Zone Representation of Intergranular Fracture Processes in Aluminum

    Science.gov (United States)

    Yamakov, Vesselin I.; Saether, Erik; Phillips, Dawn R.; Glaessgen, Edward H.

    2006-01-01

    A traction-displacement relationship that may be embedded into a cohesive zone model for microscale problems of intergranular fracture is extracted from atomistic molecular-dynamics simulations. A molecular-dynamics model for crack propagation under steady-state conditions is developed to analyze intergranular fracture along a flat 99 [1 1 0] symmetric tilt grain boundary in aluminum. Under hydrostatic tensile load, the simulation reveals asymmetric crack propagation in the two opposite directions along the grain boundary. In one direction, the crack propagates in a brittle manner by cleavage with very little or no dislocation emission, and in the other direction, the propagation is ductile through the mechanism of deformation twinning. This behavior is consistent with the Rice criterion for cleavage vs. dislocation blunting transition at the crack tip. The preference for twinning to dislocation slip is in agreement with the predictions of the Tadmor and Hai criterion. A comparison with finite element calculations shows that while the stress field around the brittle crack tip follows the expected elastic solution for the given boundary conditions of the model, the stress field around the twinning crack tip has a strong plastic contribution. Through the definition of a Cohesive-Zone-Volume-Element an atomistic analog to a continuum cohesive zone model element - the results from the molecular-dynamics simulation are recast to obtain an average continuum traction-displacement relationship to represent cohesive zone interaction along a characteristic length of the grain boundary interface for the cases of ductile and brittle decohesion. Keywords: Crack-tip plasticity; Cohesive zone model; Grain boundary decohesion; Intergranular fracture; Molecular-dynamics simulation

  13. Numerical modelling of intergranular fracture in polycrystalline materials and grain size effects

    Directory of Open Access Journals (Sweden)

    P. Wriggers

    2011-07-01

    Full Text Available In this paper, the phenomenon of intergranular fracture in polycrystalline materials is investigated using a nonlinear fracture mechanics approach. The nonlocal cohesive zone model (CZM for finite thickness interfaces recently proposed by the present authors is used to describe the phenomenon of grain boundary separation. From the modelling point of view, considering the dependency of the grain boundary thickness on the grain size observed in polycrystals, a distribution of interface thicknesses is obtained. Since the shape and the parameters of the nonlocal CZM depend on the interface thickness, a distribution of interface fracture energies is obtained as a consequence of the randomness of the material microstructure. Using these data, fracture mechanics simulations are performed and the homogenized stress-strain curves of 2D representative volume elements (RVEs are computed. Failure is the result of a diffuse microcrack pattern leading to a main macroscopic crack after coalescence, in good agreement with the experimental observation. Finally, testing microstructures characterized by different average grain sizes, the computed peak stresses are found to be dependent on the grain size, in agreement with the trend expected according to the Hall-Petch law.

  14. Extended Hall-Petch Relationships for Yield, Cleavage and Intergranular Fracture Strengths of bcc Steel and Its Deformation and Fracture Behaviors

    Science.gov (United States)

    Heo, N. H.; Heo, Y.-U.; Kwon, S. K.; Kim, N. J.; Kim, S.-J.; Lee, H.-C.

    2018-03-01

    Extended Hall-Petch relationships for yield ( σy ), cleavage ( σ_{cl} ) and intergranular fracture ( σ_{ig} ) strengths of pure iron have been established through the direct calculation of the proportional constant (k) and the estimation of the friction stress (σ0 ) . The magnitude orders of k and σ0 are generally ky causes the high work hardening rate.

  15. Stress corrosion of Zircaloy-4. Fracture mechanics study of the intergranular - transgranular transition

    International Nuclear Information System (INIS)

    Farina, Silvia B.; Duffo, Gustavo S.

    2003-01-01

    Stress corrosion cracking susceptibility of Zircaloy-4 wires was studied in 1M NaCl, 1M KBr and 1M KI aqueous solutions, and in iodine alcoholic solutions. In all cases, intergranular attack preceded transgranular propagation. It is generally accepted that the intergranular-transgranular transition occurs when a critical value of the stress intensity factor is reached. In the present work it was confirmed that the transition from intergranular to transgranular propagation cracking in Zircaloy-4 wires also occurs when a critical value of the stress intensity factor is reached. This critical stress intensity factor in wire samples is independent of the solution tested and close to 10 MPa.m-1/2. This value is in good agreement with those reported in the literature measured by different techniques. (author)

  16. Oxygen-induced intergranular fracture of the nickel-base alloy IN718 during mechanical loading at high temperatures

    Directory of Open Access Journals (Sweden)

    Krupp Ulrich

    2004-01-01

    Full Text Available There is a transition in the mechanical-failure behavior of nickel-base superalloys from ductile transgranular crack propagation to time-dependent intergranular fracture when the temperature exceeds about 600 °C. This transition is due to oxygen diffusion into the stress field ahead of the crack tip sufficient to cause brittle decohesion of the grain boundaries. Since very high cracking rates were observed during fixed-displacement loading of IN718, it is not very likely that grain boundary oxidation governs the grain-boundary-separation process, as has been proposed in several studies on the fatigue-damage behavior of the nickel-base superalloy IN718. Further studies on bicrystal and thermomechanically processed specimens of IN718 have shown that this kind of brittle fracture, which has been termed "dynamic embrittlement", depends strongly on the structure of the grain boundaries.

  17. Main factors causing intergranular and quasi-cleavage fractures at hydrogen-induced cracking in tempered martensitic steels

    Science.gov (United States)

    Kurokawa, Ami; Doshida, Tomoki; Hagihara, Yukito; Suzuki, Hiroshi; Takai, Kenichi

    2018-05-01

    Though intergranular (IG) and quasi-cleavage (QC) fractures have been widely recognized as typical fracture modes of the hydrogen-induced cracking in high-strength steels, the main factor has been unclarified yet. In the present study, the hydrogen content dependence on the main factor causing hydrogen-induced cracking has been examined through the fracture mode transition from QC to IG at the crack initiation site in the tempered martensitic steels. Two kinds of tempered martensitic steels were prepared to change the cohesive force due to the different precipitation states of Fe3C on the prior γ grain boundaries. A high amount of Si (H-Si) steel has a small amount of Fe3C on the prior austenite grain boundaries. Whereas, a low amount of Si (L-Si) steel has a large amount of Fe3C sheets on the grain boundaries. The fracture modes and initiations were observed using FE-SEM (Field Emission-Scanning Electron Microscope). The crack initiation sites of the H-Si steel were QC fracture at the notch tip under various hydrogen contents. While the crack initiation of the L-Si steel change from QC fracture at the notch tip to QC and IG fractures from approximately 10 µm ahead of the notch tip as increasing in hydrogen content. For L-Si steels, two possibilities are considered that the QC or IG fracture occurred firstly, or the QC and IG fractures occurred simultaneously. Furthermore, the principal stress and equivalent plastic strain distributions near the notch tip were calculated with FEM (Finite Element Method) analysis. The plastic strain was the maximum at the notch tip and the principle stress was the maximum at approximately 10 µm from the notch tip. The position of the initiation of QC and IG fracture observed using FE-SEM corresponds to the position of maximum strain and stress obtained with FEM, respectively. These findings indicate that the main factors causing hydrogen-induced cracking are different between QC and IG fractures.

  18. Risk of fracture and pneumonia from acid suppressive drugs.

    Science.gov (United States)

    Eom, Chun-Sick; Lee, Sang-Soo

    2011-09-26

    A recently published systematic review and meta-analysis, incorporating all relevant studies on the association of acid suppressive medications and pneumonia identified up to August 2009, revealed that for every 200 patients, treated with acid suppressive medication, one will develop pneumonia. They showed the overall risk of pneumonia was higher among people using proton pump inhibitors (PPIs) [adjusted odds ratio (OR) = 1.27, 95% CI: 1.11-1.46, I(2) = 90.5%] and Histamine-2 receptor antagonists (H2RAs) (adjusted OR = 1.22, 95% CI: 1.09-1.36, I(2) = 0.0%). In the randomized controlled trials, use of H2RAs was associated with an elevated risk of hospital-acquired pneumonia (relative risk 1.22, 95% CI: 1.01-1.48, I(2) = 30.6%). Another meta-analysis of 11 studies published between 1997 and 2011 found that PPIs, which reduce stomach acid production, were associated with increased risk of fracture. The pooled OR for fracture was 1.29 (95% CI: 1.18-1.41) with use of PPIs and 1.10 (95% CI: 0.99-1.23) with use of H2RAs, when compared with non-use of the respective medications. Long-term use of PPIs increased the risk of any fracture (adjusted OR = 1.30, 95% CI: 1.15-1.48) and of hip fracture risk (adjusted OR = 1.34, 95% CI: 1.09-1.66), whereas long-term H2RA use was not significantly associated with fracture risk. Clinicians should carefully consider when deciding to prescribe acid-suppressive drugs, especially for patients who are already at risk for pneumonia and fracture. Since it is unnecessary to achieve an achlorhydric state in order to resolve symptoms, we recommend using the only minimum effective dose of drug required to achieve the desired therapeutic goals.

  19. Intergranular corrosion protective of austenitic stainless steel chemical equipment

    International Nuclear Information System (INIS)

    Kuzyukov, A.N.

    1994-01-01

    A complex of protective measures was developed for each concrete case of intergranular fracture of equipment, i.e.: decrease in the level of strains, surfacing with materials resistant to intergranular fracture under the conditions; permissible correction of process parameters, permitting a shift in corrosion potential towards decrease in the rate of intergranular corrosion. It is shown that even if the eguipment was subject to interfranular corrosion, but the fracture is not of catastrophic character, it proved possible to develop and apply complex methods of protection from the above types of corrosion fracture and to elongate the service life by 5-15 years

  20. Study of intergranular embrittlement in Fe-12Mn alloys

    International Nuclear Information System (INIS)

    Lee, H.J.

    1982-06-01

    A high resolution scanning Auger microscopic study has been performed on the intergranular fracture surfaces of Fe-12Mn steels in the as-austenitized condition. Fracture mode below the ductile-brittle transition temperature was intergranular whenever the alloy was quenched from the austenite field. The intergranular fracture surface failed to reveal any consistent segregation of P, S, As, O, or N. The occasional appearance of S or O on the fracture surface was found to be due to a low density precipitation of MnS and MnO 2 along the prior austenite boundaries. An AES study with Ar + ion-sputtering showed no evidence of manganese enrichment along the prior austenite boundaries, but a slight segregation of carbon which does not appear to be implicated in the tendency toward intergranular fracture. Addition of 0.002% B with a 1000 0 C/1h/WQ treatment yielded a high Charpy impact energy at liquid nitrogen temperature, preventing the intergranular fracture. High resolution AES studies showed that 3 at. % B on the prior austenite grain boundaries is most effective in increasing the grain boundary cohesive strength in an Fe-12Mn alloy. Trace additions of Mg, Zr, or V had negligible effects on the intergranular embrittlement. A 450 0 C temper of the boron-modified alloys was found to cause tempered martensite embrittlement, leading to intergranular fracture. The embrittling treatment of the Fe-12Mn alloys with and without boron additions raised the ductile-brittle transition by 150 0 C. This tempered martensite embrittlement was found to be due to the Mn enrichment of the fracture surface to 32 at. % Mn in the boron-modified alloy and 38 at. % Mn in the unmodified alloy. The Mn-enriched region along the prior austenite grain boundaries upon further tempering is believed to cause nucleation of austenite and to change the chemistry of the intergranular fracture surfaces. 61 figures

  1. Critical current of the nonuniform Josephson transition at intergranular boundary with random dislocation distribution

    International Nuclear Information System (INIS)

    Mejlikhov, E.Z.; Farzetdinova, R.M.

    1997-01-01

    Critical current of inhomogeneous intergranular Josephson transition is calculated in the assumption concerning superconductivity suppression by local strains of boundary dislocations with random distribution

  2. Intergranular brittle fracture of a low alloy steel induced by grain boundary segregation of impurities: influence of the microstructure; Rupture intergranulaire fragile d'un acier faiblement allie induite par la segregation d'impuretes aux joints de grains: influence de la microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Raoul, St

    1999-07-01

    The study contributes to improve the comprehension of intergranular embrittlement induced by the phosphorus segregation along prior austenitic grain boundaries of low alloy steels used in pressurized power reactor vessel. A part of this study was performed using a A533 steel which contains chemical fluctuations (ghost lines) with two intensities. Axi-symmetrically notched specimens were tested and intergranular brittle de-cohesions were observed in the ghost lines. The fracture initiation sites observed on fracture surfaces were identified as MnS inclusions. A bimodal statistic obtained in a probabilistic model of the fracture is explained by the double population of ghost lines' intensities. A metallurgical study was performed on the same class of steel by studying the influence of the microstructure on the susceptibility to temper embrittlement. Brittle fracture properties of such microstructures obtained by dilatometric experiments were tested on sub-sized specimens to measure the V-notched fracture toughness. Fraction areas of brittle fracture modes were determined on surface fractures. A transition of the fracture mode with the microstructure is observed. It is shown that tempered microstructures of martensite and lower bainite are more susceptible to intergranular embrittlement than tempered upper bainitic microstructure. The intergranular fracture is the most brittle mode. The analysis of crystalline mis-orientations shows a grain boundary structure appreciably more coherent for tempered microstructures of martensite and lower bainite. The higher density of randomgrain boundaries is susceptible to drag the phosphorus in the upper bainitic matrix and to make the quantity of free phosphorus decreasing. Microstructure observations show a difference in the size and the spatial distribution of carbides, essentially cementite, between tempered martensite and upper bainite. It can explain the bigger susceptibility of this last microstructure to cleavage mode

  3. Contribution of solution pH and buffer capacity to suppress intergranular stress corrosion cracking of sensitized type 304 stainless steel at 95 C

    International Nuclear Information System (INIS)

    Zhang, S.; Shibata, T.; Haruna, T.

    1999-01-01

    Controlling pH of high-temperature water to ∼pH 7 at 300 C by adding lithium hydroxide (LiOH) into the coolant system of a pressurized water reactor (PWR) successfully has been mitigating the corrosion of PWR component materials. The effects of solution pH and buffer capacity on intergranular stress corrosion cracking (IGSCC) of sensitized type 304 stainless steel ([SS] UNS S30400) was examined at 95 C by slow strain rate technique (SSRT) with an in-situ cracking observation system. It was found that an increase in solution pH or buffer capacity increased crack initiation time and decreased mean crack initiation frequency, but exerted almost no effect on crack propagation. This inhibition effect on IGSCC initiation was explained as resulting from a retarding effect of solution pH and buffer capacity on the decrease in pH at crack nuclei caused by the hydrolysis of metal ions dissolved when the passive film was ruptured by strain in SSRT

  4. Micromechanical Aspects of Transgranular and Intergranular Failure Competition

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Tarafder, M.; Hadraba, Hynek

    2011-01-01

    Roč. 465, - (2011), s. 399-402 ISSN 1013-9826 R&D Projects: GA ČR(CZ) GAP107/10/0361 Institutional research plan: CEZ:AV0Z20410507 Keywords : intergranular fracture * cleavage * fracture toughness Subject RIV: JL - Materials Fatigue, Friction Mechanics

  5. Simulations of intergranular fracture in nanocrystalline molybdenum

    DEFF Research Database (Denmark)

    Frederiksen, Søren Lund; Jacobsen, Karsten Wedel; Schiøtz, Jakob

    2004-01-01

    Using molecular dynamics simulations we investigate the plastic deformation of nanocrystalline molybdenum with a grain size of 12 nm at high strain rates. The simulations are performed with an interatomic potential which is obtained through matching of atomic forces to a database generated...... with density-functional calculations. The simulations show the plastic deformation to involve both grain boundary processes and dislocation migration which in some cases lead to twin boundary formation. A large component of the strain is accommodated through the formation of cracks in the grain boundaries...

  6. Grain boundary segregation and intergranular failure

    International Nuclear Information System (INIS)

    White, C.L.

    1980-01-01

    Trace elements and impurities often segregate strongly to grain boundaries in metals and alloys. Concentrations of these elements at grain boundaries are often 10 3 to 10 5 times as great as their overall concentration in the alloy. Because of such segregation, certain trace elements can exert a disproportionate influence on material properties. One frequently observed consequence of trace element segregation to grain boundaries is the occurrence of grain boundary failure and low ductility. Less well known are incidences of improved ductility and inhibition of grain boundary fracture resulting from trace element segregation to grain boundaries in certain systems. An overview of trace element segregation and intergranular failure in a variety of alloy systems as well as preliminary results from studies on Al 3% Li will be presented

  7. Intergranular stresses in Incoloy-800

    International Nuclear Information System (INIS)

    Holden, T.M.; Holt, R.A.; Clarke, A.P.

    1997-01-01

    The generation of intergranular residual strains under uniaxial loading conditions in the plastic regime has been measured in detail by neutron diffraction in Incoloy-800. A relatively simple theory, based on the Taylor model, gives a good semiquantitative account of the magnitudes of the strains. The results clarify the interpretation of measurements made earlier on Incoloy-800 steam generator tubes. (author)

  8. Dependence of fracture toughness of molybdenum laser welds on dendritic spacing and in situ titanium additions

    International Nuclear Information System (INIS)

    Jellison, J.L.

    1979-01-01

    The fracture toughness of molybdenum welds has been improved by in situ gettering of oxygen by means of physically deposited titanium. The addition of titanium suppressed brittle intergranular fracture. Pulsed laser welds (both Nd:YAG and CO 2 ) exhibited superior toughness to that of continuous wave CO 2 laser welds. Also, welds of vacuum arc remelted grades were tougher than those of sintered molybdenum. However, weld toughness could not be correlated with either oxygen or carbon content

  9. Origin of intergranular embrittlement of Al alloys induced by Na and Ca segregation: Grain boundary weakening

    International Nuclear Information System (INIS)

    Lu Guanghong; Zhang Ying; Deng Shenghua; Wang Tianmin; Kohyama, Masanori; Yamamoto, Ryoichi; Liu Feng; Horikawa, Keitaro; Kanno, Motohiro

    2006-01-01

    Using a first-principles computational tensile test, we show that the ideal tensile strength of an Al grain boundary (GB) is reduced with both Na and Ca GB segregation. We demonstrate that the fracture occurs in the GB interface, dominated by the break of the interfacial bonds. Experimentally, we further show that the presence of Na or Ca impurity, which causes intergranular fracture, reduces the ultimate tensile strength when embrittlement occurs. These results suggest that the Na/Ca-induced intergranular embrittlement of an Al alloy originates mainly from the GB weakening due to the Na/Ca segregation

  10. Fat-suppressed T2-weighted MRI appearance of subchondral insufficiency fracture of the femoral head

    Energy Technology Data Exchange (ETDEWEB)

    Sonoda, Kazuhiko; Yamamoto, Takuaki; Motomura, Goro; Karasuyama, Kazuyuki; Kubo, Yusuke; Iwamoto, Yukihide [Kyushu University, Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Higashi-ku, Fukuoka (Japan)

    2016-11-15

    Our aims were to investigate the imaging appearance of subchondral insufficiency fracture (SIF) of the femoral head based on fat-suppressed T2-weighted MRI, and evaluate its correlation with the clinical outcomes following conservative treatment. We retrospectively evaluated 40 hips in 37 patients with SIF of the femoral head (12 males and 25 females; mean age 55.8 years, range 22-78 years). MRI examinations were performed within 3 months after the onset of hip pain. Using fat-suppressed T2-weighted imaging, we evaluated the hips for the intensity of the subchondral bone (corresponding to the area superior to the low intensity band on T1-weighted images) as well as bone marrow edema, joint effusion, and presence of the band lesion. We then correlated the intensity of the subchondral bone with clinical outcomes. The hips were classified into three types based on subchondral intensity on fat-suppressed T2-weighted images: type 1 (21 hips) showed high intensity, type 2 (eight hips) showed heterogeneous intensity, and type 3 (11 hips) showed low intensity. The mean period between pain onset and MRI examination was significantly longer for type 2 hips than for type 1. Healing rates were 86 % for type 1, 75 % for type 2, and 18 % for type 3. SIF cases were classified into three types based on subchondral intensity on fat-suppressed T2-weighted imaging performed within 3 months after pain onset. Type 3 SIF tended to be intractable to conservative treatment compared to type 1 and type 2. (orig.)

  11. Influence of sulfur, phosphorus, and antimony segregation on the intergranular hydrogen embrittlement of nickel

    International Nuclear Information System (INIS)

    Bruemmer, S.M.; Baer, D.R.; Jones, R.H.; Thomas, M.T.

    1983-01-01

    The effectiveness of sulfur, phosphorus, and antimony in promoting the intergranular embrittlement of nickel was investigated using straining electrode tests in 1N H 2 SO 4 at cathodic potentials. Sulfur was found to be the critical grain boundary segregant due to its large enrichment at grain boundaries (10 4 to 10 5 times the bulk content) and the direct relationship between sulfur coverage and hydrogeninduced intergranular failure. Phosphorus was shown to be significantly less effective than sulfur or antimony in inducing the intergranular hydrogen embrittlement of nickel. The addition of phosphoru to nickel reduced the tendency for intergranular fracture and improved ductility because phosphoru segregated strongly to grain interfaces and limited sulfur enrichment. The hydrogen embrittling potency of antimony was also less than that of sulfur while its segregation propensity was considerably less. It was found that the effectiveness of segregated phosphorus and antimony in prompting inter granular embrittlement vs that of sulfur could be expressed in terms of an equivalent grain boundary sulfur coverage. The relative hydrogen embrittling potencies of sulfur, phosphorus, and antimony are discussed in reference to general mechanisms for the effect of impurity segregation on hydrogeninduced intergranular fracture

  12. Effect of Zr addition on intergranular corrosion of low-chromium ferritic stainless steel

    International Nuclear Information System (INIS)

    Park, Jin Ho; Kim, Jeong Kil; Lee, Bong Ho; Seo, Hyung Suk; Kim, Kyoo Young

    2014-01-01

    Addition of Zr to low-Cr ferritic stainless steel forms a mixture of ZrC and Fe 23 Zr 6 precipitates that can prevent intergranular corrosion. Transmission electron microscopy and three-dimensional atom probe analysis suggest that the ZrC and Fe 23 Zr 6 mixture prevents intergranular corrosion in two ways: by acting as a strong carbide former to suppress the formation of Cr-carbide and by acting as a barrier against the diffusion of the solute Cr towards the grain boundary

  13. ON THE ORIGIN OF INTERGRANULAR JETS

    International Nuclear Information System (INIS)

    Yurchyshyn, V. B.; Goode, P. R.; Abramenko, V. I.; Steiner, O.

    2011-01-01

    We observe that intergranular jets, originating in the intergranular space surrounding individual granules, tend to be associated with granular fragmentation, in particular, with the formation and evolution of a bright granular lane (BGL) within individual granules. The BGLs have recently been identified as vortex tubes by Steiner et al. We further discover the development of a well-defined bright grain located between the BGL and the dark intergranular lane to which it is connected. Signatures of a BGL may reach the lower chromosphere and can be detected in off-band Hα images. Simulations also indicate that vortex tubes are frequently associated with small-scale magnetic fields. We speculate that the intergranular jets detected in the New Solar Telescope (NST) data may result from the interaction between the turbulent small-scale fields associated with the vortex tube and the larger-scale fields existing in the intergranular lanes. The intergranular jets are much smaller and weaker than all previously known jet-like events. At the same time, they appear much more numerous than the larger events, leading us to the speculation that the total energy release and mass transport by these tiny events may not be negligible in the energy and mass-flux balance near the temperature minimum atop the photosphere. The study is based on the photospheric TiO broadband (1.0 nm) filter data acquired with the 1.6 m NST operating at the Big Bear Solar Observatory. The data set also includes NST off-band Hα images collected through a Zeiss Lyot filter with a passband of 0.025 nm.

  14. Intergranular Cracking as a Major Cause of Long-Term Capacity Fading of Layered Cathodes.

    Science.gov (United States)

    Liu, Hao; Wolf, Mark; Karki, Khim; Yu, Young-Sang; Stach, Eric A; Cabana, Jordi; Chapman, Karena W; Chupas, Peter J

    2017-06-14

    Capacity fading has limited commercial layered Li-ion battery electrodes to NCA) electrode change after capacity fade following months of slow charge-discharge. The changes in the reactions that underpin energy storage after long-term cycling directly correlate to the capacity loss; heterogeneous reaction kinetics observed during extended cycles quantitatively account for the capacity loss. This reaction heterogeneity is ultimately attributed to intergranular fracturing that degrades the connectivity of subsurface grains within the polycrystalline NCA aggregate.

  15. A multiscale constitutive model for intergranular stress corrosion cracking in type 304 austenitic stainless steel

    International Nuclear Information System (INIS)

    Siddiq, A; Rahimi, S

    2013-01-01

    Intergranular stress corrosion cracking (IGSCC) is a fracture mechanism in sensitised austenitic stainless steels exposed to critical environments where the intergranular cracks extends along the network of connected susceptible grain boundaries. A constitutive model is presented to estimate the maximum intergranular crack growth by taking into consideration the materials mechanical properties and microstructure characters distribution. This constitutive model is constructed based on the assumption that each grain is a two phase material comprising of grain interior and grain boundary zone. The inherent micro-mechanisms active in the grain interior during IGSCC is based on crystal plasticity theory, while the grain boundary zone has been modelled by proposing a phenomenological constitutive model motivated from cohesive zone modelling approach. Overall, response of the representative volume is calculated by volume averaging of individual grain behaviour. Model is assessed by performing rigorous parametric studies, followed by validation and verification of the proposed constitutive model using representative volume element based FE simulations reported in the literature. In the last section, model application is demonstrated using intergranular stress corrosion cracking experiments which shows a good agreement

  16. Computational multiscale modeling of intergranular cracking

    International Nuclear Information System (INIS)

    Simonovski, Igor; Cizelj, Leon

    2011-01-01

    A novel computational approach for simulation of intergranular cracks in a polycrystalline aggregate is proposed in this paper. The computational model includes a topological model of the experimentally determined microstructure of a 400 μm diameter stainless steel wire and automatic finite element discretization of the grains and grain boundaries. The microstructure was spatially characterized by X-ray diffraction contrast tomography and contains 362 grains and some 1600 grain boundaries. Available constitutive models currently include isotropic elasticity for the grain interior and cohesive behavior with damage for the grain boundaries. The experimentally determined lattice orientations are employed to distinguish between resistant low energy and susceptible high energy grain boundaries in the model. The feasibility and performance of the proposed computational approach is demonstrated by simulating the onset and propagation of intergranular cracking. The preliminary numerical results are outlined and discussed.

  17. Diffusive intergranular cavity growth in creep in tension and torsion

    International Nuclear Information System (INIS)

    Stanzl, S.E.; Argon, A.S.; Tschegg, E.K.

    1983-01-01

    Creep experiments were performed at 500 C in tension and torsion on high conductivity copper tubes with a uniform initial coverage of implanted water vapor bubbles on all grain boundaries. No significant differences were found in the times to fracture over a wide stress range when the results were correlated according to the maximum principal tensile stress in the two fields. The results indicate that the cavities grow in a crack-like mode but at one tenth the rate predicted from the theoretical model of Pharr and Nix. This difference is attributed partly to load shedding from boundaries normal to the maximum principal tensile stress to slanted boundaries, and partly to a lack of knowledge about th surface diffusion constant. The results indicate further that the contribution to intergranular cavity growth by power-law creep in negligible in comparison to the contribution by diffusional flow. Complementary tension and torsion experiments performed in initially uncavitated samples results in shorter creep lives in torsion than in tension due to more effective cavity nucleation in the former. The times to fracture in both of these cases obey Monkman and Grant's law, indicating the presence of constraints on growth by the lagging deformations by power-law creep in the surroundings of the cavitating isolated grain facets

  18. Physical fracture properties (fracture surfaces as information sources; crackgrowth and fracture mechanisms; exemples of cracks)

    International Nuclear Information System (INIS)

    Meny, Lucienne.

    1979-06-01

    Fracture surfaces are considered as a useful source of informations: an introduction to fractography is presented; the fracture surface may be observed through X ray microanalysis, and other physical methods such as Auger electron spectroscopy or secundary ion emission. The mechanisms of macroscopic and microscopic crackgrowth and fracture are described, in the case of unstable fracture (cleavage, ductile with shear, intergranular brittleness) and of progressive crack propagation (creep, fatigue). Exemples of cracks are presented in the last chapter [fr

  19. A stereological approach for measuring the groove angles of intergranular corrosion

    International Nuclear Information System (INIS)

    Gwinner, B.; Borgard, J.-M.; Dumonteil, E.; Zoia, A.

    2017-01-01

    Highlights: • The ICG morphology has been characterized in 3D by X-ray μ-tomography. • The measurement of the angles of the IGC groove on 2D cross sections induces a bias. • A methodology is proposed to estimate the true value of the IGC groove angles in 3D. - Abstract: Non-sensitized austenitic stainless steels can be prone to intergranular corrosion when they are in contact with an oxidizing medium like nitric acid. Intergranular corrosion is characterized by the formation of grooves along the grain boundaries. The angle of these grooves is a key parameter, which directly informs of the intergranular corrosion kinetics. Most of the time, the angles of the grooves are experimentally measured on 2-dimensional cross sections of the corroded samples. This study discusses the relationship between the groove angle measured on 2-dimensional sections and the true groove angle in 3-dimensional space. This approach could also be easily extended to the study of crack angle in the domains of corrosion-fatigue, stress corrosion cracking or mechanical fracture.

  20. Grain boundary segregation of elements of groups 14 and 15 and its consequences for intergranular cohesion of ferritic iron

    Czech Academy of Sciences Publication Activity Database

    Lejček, Pavel; Šandera, P.; Horníková, J.; Řehák, Petr; Pokluda, J.

    2017-01-01

    Roč. 52, č. 10 (2017), s. 5822-5834 ISSN 0022-2461 R&D Projects: GA ČR GAP108/12/0144; GA MŠk(CZ) LQ1601 Institutional support: RVO:68378271 ; RVO:68081723 Keywords : grain boundary segregation * segregation enthalpy * intergranular fracture * strengthening/embrittling energy Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.599, year: 2016

  1. Simulation of Intergranular Ductile Cracking in β Titanium Alloys Based on a Micro-Mechanical Damage Model.

    Science.gov (United States)

    Li, Huan; Li, Jinshan; Tang, Bin; Fan, Jiangkun; Yuan, Huang

    2017-10-30

    The intergranular crack propagation of the lamellar structure β titanium alloys is investigated by using a modified Gurson-type damage model. The representative microstructure of the lamellar alloy, which consists of the soft α phase layer surrounding the hard grain interiors, is generated based on an advanced Voronoi algorithm. Both the normal fracture due to void growth and the shear fracture associated with void shearing are considered for the grain boundary α layer. The individual phase properties are determined according to the experimental nanoindentation result and the macroscopic stress-strain curve from a uni-axial tensile test. The effects of the strain hardening exponent of the grain interiors and the void shearing mechanism of the grain boundary α layer on fracture toughness and the intergranular crack growth behavior are emphatically studied. The computational predictions indicate that fracture toughness can be increased with increasing the strain hardening ability of the grain interiors and void shearing can be deleterious to fracture toughness. Based on the current simulation technique, qualitative understanding of relationships between the individual phase features and the fracture toughness of the lamellar alloys can be obtained, which provides useful suggestions to the heat treatment process of the β titanium alloys.

  2. Intergranular creep of oriented bi-crystals of aluminium

    International Nuclear Information System (INIS)

    Biscondi, Michel

    1971-01-01

    This research thesis reports the study of the nature of intergranular creep, and of relationships between structure and creep ability of some grain boundaries. After having explained why bi-crystals are interesting for this kind of study, the author defines experimental conditions and describes measurement methods. He reports the study of the influence of external factors (time, test temperature, applied stress) on intergranular creep. He shows that grain boundary structure has a determining influence of the grain boundary ability to intergranular creep. The author discusses the obtained results and makes some propositions for the interpretation of the observed phenomenon

  3. Oxidation assisted intergranular cracking under loading at dynamic strain aging temperatures in Inconel 718 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Rezende, M.C., E-mail: monica_crezende@hotmail.com [Universidade Federal do Rio de Janeiro, Departamento de Engenharia Metalúrgica e de Materiais, C.P. 68505, Rio de Janeiro 21945-970 (Brazil); Araújo, L.S.; Gabriel, S.B. [Universidade Federal do Rio de Janeiro, Departamento de Engenharia Metalúrgica e de Materiais, C.P. 68505, Rio de Janeiro 21945-970 (Brazil); Dille, J. [Université Libre de Bruxelles, 4MAT Department, Av. F. Roosevelt 50, C.P. 194/03, Brussels (Belgium); Almeida, L.H. de [Universidade Federal do Rio de Janeiro, Departamento de Engenharia Metalúrgica e de Materiais, C.P. 68505, Rio de Janeiro 21945-970 (Brazil)

    2015-09-15

    Highlights: • Mechanical properties are controlled by DSA, precipitation hardening and OAIC. • Between 600 and 700 °C the critical strain for serrations increases with temperature. • This is related to the consumption of matrix elements (especially Nb: for γ′ and γ″). • A reduction in ductility occurs (related to the OAIC) when the DSA is no longer effective. • This reduction is accompanied by an increase in intergranular brittle fracture. - Abstract: It is well established that 718 superalloy exhibits brittle intergranular cracking when deformed under tension at temperatures above 600 °C. This embrittlement effect is related with grain boundary penetration by oxygen (Oxygen Assisted Intergranular Cracking – OAIC). Simultaneously, impacting on its mechanical properties, the precipitation of coherent γ′ and γ″ phases occur above 650 °C and Dynamic Strain Aging (DSA) occurs in the temperature range between 200 and 800 °C. Although literature indicates that OAIC is the mechanism that controls mechanical properties at high temperatures, its interactions with DSA and precipitation are still under discussion. The objective of this work is to investigate the interactions between the embrittlement phenomena (OAIC and DSA) and the hardening mechanism of γ′ and γ″ precipitation on the mechanical properties of an annealed 718 superalloy. Tensile tests were performed at a strain rate of 3.2 × 10{sup −4} s{sup −1} under secondary vacuum, in temperatures ranging from 200 to 800 °C. Fracture surfaces were observed by scanning electron microscopy (SEM) and precipitation by transmission electron microscopy (TEM). The effect of DSA and precipitation on the strength and of OAIC on the ductility was verified.

  4. Cutting of metal components by intergranular cracking

    International Nuclear Information System (INIS)

    Chavand, J.; Gauthier, A.; Lopez, J.J.; Tanis, G.

    1985-01-01

    The objective of this contract was to study a new steel-sheet cutting technique for dismantling nuclear installations without in principle producing secondary waste. This technique is based on intergranular cracking of steel induced by the combined action of penetration of molten metal into the steel and application of a mechanical load. Cutting has been achieved for stainless-steel sheets with thicknesses ranging from a few mm to 50 mm and for carbon-steel plates with thicknesses between 20 and 60 mm. For carbon steel is seems possible that components as thick as 100 mm can be cut. The tests have permitted selection of the heating methods and determination of the cracking parameters for the materials and range of thickness studied. In the case of thin sheets, results were obtained for cutting in varied positions suited to the techniques of dismantling in hot cells. A temperature-measuring system using an infrared camera has been developed to determine the variation of the temperature field established in the component. In association with the three-dimensional computation code COCO developed by the CEA, this system permits prediction of the changes in stresses in the cracked zone when the cutting parameters are modified. 34 figs

  5. Intergranular attack evaluation from hideout return

    International Nuclear Information System (INIS)

    Nordmann, F.; Dupin, M.; Menet, O.; Fiquet, J.-M.

    1989-01-01

    Intergranular Attack (IGA) is the secondary side corrosion mechanism on PWR steam generator tubing, which can occur most frequently even with a good waterchemistry. It has moderately developed in a few French units. Consequently, several remedies have been implemented, such as sodium content decrease in makeup water and application of more stringent chemistry specifications. In order to evaluate the local chemistry in restricted areas where IGA may occur, a large hideout return programme has been carried out on many units. It shows that free alkalinity returning during shutdown is usually ranging from 0.5 to 5 g of sodium per steam generator, and that the required time to let it return is about 40 hours. However, high temperature pH calculations indicate that such an amount of alkalinity can correspond to a potentially corrosive solution in restricted areas, where a concentration factor of 10 5 to 10 7 can be reached, inducing a pH of 10 at 300 o C. Studies are still in progress in order to define when a shutdown should be required to allow hideout return and help to prevent IGA. (author)

  6. Interphase and intergranular stress generation in carbon steels

    International Nuclear Information System (INIS)

    Oliver, E.C.; Daymond, M.R.; Withers, P.J.

    2004-01-01

    Neutron diffraction spectra have been acquired during tensile straining of high and low carbon steels, in order to compare the evolution of internal stress in ferritic steel with and without a reinforcing phase. In low carbon steel, the generation of intergranular stresses predominates, while in high carbon steel similar intergranular stresses among ferrite grain families are superposed upon a large redistribution of stress between phases. Comparison is made to calculations using elastoplastic self-consistent and finite element methods

  7. Study of twist boundaries in aluminium. Structure and intergranular diffusion

    International Nuclear Information System (INIS)

    Lemuet, Daniel

    1981-01-01

    This research thesis addresses the study of grain boundaries in oriented crystals, and more particularly the systematic calculation of intergranular structures and energies of twist boundaries of <001> axis in aluminium, the determination of intergranular diffusion coefficients of zinc in a set of twist bi-crystals of same axis encompassing a whole range of disorientations, and the search for a correlation between these experimental results and calculated structures

  8. Initiation model for intergranular stress corrosion cracking in BWR pipes

    International Nuclear Information System (INIS)

    Hishida, Mamoru; Kawakubo, Takashi; Nakagawa, Yuji; Arii, Mitsuru.

    1981-01-01

    Discussions were made on the keys of intergranular stress corrosion cracking of austenitic stainless steel in high-temperature water in laboratories and stress corrosion cracking incidents in operating plants. Based on these discussions, a model was set up of intergranular stress corrosion cracking initiation in BWR pipes. Regarding the model, it was presumed that the intergranular stress corrosion cracking initiates during start up periods whenever heat-affected zones in welded pipes are highly sensitized and suffer dynamic strain in transient water containing dissolved oxygen. A series of BWR start up simulation tests were made by using a flowing autoclave system with slow strain rate test equipment. Validity of the model was confirmed through the test results. (author)

  9. Assessing resistance of stabilized corrosion resistant steels to intergranular corrosion

    International Nuclear Information System (INIS)

    Karas, A.; Cihal, V. Jr.; Vanek, V.; Herzan, J.; Protiva, K.; Cihal, V.

    1987-01-01

    Resistance to intergranular corrosion was determined for four types of titanium-stabilized steels from the coefficients of stabilization efficiency according to the degree the chemical composition was known. The ATA SUPER steel showed the highest resistance parameter value. The resistance of this type of steel of a specific composition, showing a relatively low value of mean nitrogen content was compared with steel of an optimized chemical composition and with low-carbon niobium stabilized, molybdenum modified steels. The comparison showed guarantees of a sufficient resistance of the steel to intergranular corrosion. The method of assessing the resistance to intergranular corrosion using the calculation of the minimum content of Cr', i.e., the effective chromium content, and the maximum effective carbon content C' giving the resistance parameter k seems to be prospective for practical use in the production of corrosion resistant steels. (author). 1 tab., 5 figs., 15 refs

  10. Intergranular stress corrosion cracking of sensitized stainless steels. Final report

    International Nuclear Information System (INIS)

    Vyas, B.; Isaacs, H.S.; Weeks, J.R.

    1976-12-01

    A study was conducted of the intergranular stress corrosion cracking of materials used in Boiling Water Reactors (BWR) aimed at developing an understanding of the mechanism(s) of this mode of failure and at developing tests to determine the susceptibility of a given material to this form of attack

  11. Intergranular and inter-phased boundaries in the materials

    International Nuclear Information System (INIS)

    Aslanides, A.; Backhaus-Ricoult, M.; Bayle-Guillemaud, P.

    2000-01-01

    This document collects the abstracts of the talks presented during the colloquium J2IM on the intergranular and inter-phased boundaries in the materials. Around the themes of the interfaces behaviour and grain boundaries defects in materials, these days dealt with the microstructure behaviour in many domains such as the interfaces in batteries, the irradiation damages and the special case of the fuel-cladding interactions, the stressed interfaces, the alumina or silicon carbides substrates. (A.L.B.)

  12. Evaluation of intergranular corrosion rate and microstructure of forged 316L round bar

    International Nuclear Information System (INIS)

    Lim, H. K.; Kim, Y. S.

    2009-01-01

    When austenitic stainless steels are heat treated in the range of 500∼850 .deg. C, the alloys are sensitized due to the formation of chromium carbide at grain boundaries and then intergranular corrosion occurs. This paper aims to evaluate the intergranular corrosion rate and microstructural change of forged 316L stainless steel. To analyze the microstructure by forging conditions, ferrite phase, sigma phase, intergranular precipitation were observed. In order to evaluate the intergranular corrosion rate. Huey test was performed by ASTM A262. On the base of microstructural observation, ferrite and sigma phases were not detected, and also intergranular precipitation was not revealed in optical microscopic observation. By ASTM A262 Practice A, step structure was shown in all forging conditions. Intergranular corrosion rate gradually increased by Huey test periods but average corrosion rate was under 0.03 mm/month

  13. Evaluation of intergranular corrosion rate and microstructure of forged 316L round bar

    Energy Technology Data Exchange (ETDEWEB)

    Lim, H. K.; Kim, Y. S. [Andong National University, Andong (Korea, Republic of)

    2009-12-15

    When austenitic stainless steels are heat treated in the range of 500{approx}850 .deg. C, the alloys are sensitized due to the formation of chromium carbide at grain boundaries and then intergranular corrosion occurs. This paper aims to evaluate the intergranular corrosion rate and microstructural change of forged 316L stainless steel. To analyze the microstructure by forging conditions, ferrite phase, sigma phase, intergranular precipitation were observed. In order to evaluate the intergranular corrosion rate. Huey test was performed by ASTM A262. On the base of microstructural observation, ferrite and sigma phases were not detected, and also intergranular precipitation was not revealed in optical microscopic observation. By ASTM A262 Practice A, step structure was shown in all forging conditions. Intergranular corrosion rate gradually increased by Huey test periods but average corrosion rate was under 0.03 mm/month.

  14. Intergranular penetration of liquid gold into stainless steel

    OpenAIRE

    Favez, Denis; Deillon, Léa; Wagnière, Jean-Daniel; Rappaz, Michel

    2011-01-01

    Intergranular penetration of liquid 18 K gold into a superaustenitic stainless steel, which occurs during laser welding of these two materials, has been studied using a C-ring device which can be put under tensile stresses by a screw. It is shown that liquid gold at 1000 degrees C penetrates the immersed stainless steel C-ring at grain boundaries, but only when tensile stresses are applied. Based on the thickness of the peritectic phase that forms all along the liquid crack and on the transve...

  15. Intergranular corrosion susceptibility in supermartensitic stainless steel weldments

    Energy Technology Data Exchange (ETDEWEB)

    Aquino, J.M. [Sao Carlos Federal University (UFSCar), Materials Engineering Department, Rodovia Washington Luis, km 235, CEP 13565-905, Sao Carlos, SP (Brazil)], E-mail: dsek@power.ufscar.br; Della Rovere, C.A.; Kuri, S.E. [Sao Carlos Federal University (UFSCar), Materials Engineering Department, Rodovia Washington Luis, km 235, CEP 13565-905, Sao Carlos, SP (Brazil)

    2009-10-15

    The intergranular corrosion susceptibility in supermartensitic stainless steel (SMSS) weldments was investigated by the double loop - electrochemical potentiokinetic reactivation (DL-EPR) technique through the degree of sensitization (DOS). The results showed that the DOS decreased from the base metal (BM) to the weld metal (WM). The heat affected zone (HAZ) presented lower levels of DOS, despite of its complex precipitation mechanism along the HAZ length. Chromium carbide precipitate redissolution is likely to occur due to the attained temperature at certain regions of the HAZ during the electron beam welding (EBW). Scanning electron microscopy (SEM) images showed preferential oxidation sites in the BM microstructure.

  16. Intergranular stress corrosion in soldered joints of stainless steel 304

    International Nuclear Information System (INIS)

    Zamora R, L.

    1994-01-01

    The intergranular stress cracking of welded joints of austenitic stainless steel, AISI 304, is a serious problem in BWR type reactors. It is associated with the simultaneous presence of three factors; stress, a critical media and sensibilization (DOS). EPR technique was used in order to verify the sensibilization degree in the base metal, and the zone affected by heat and welding material. The characterization of material was done. The objective of this work is the study of microstructure and the evaluation of EPR technique used for the determination of DOS in a welded plate of austenitic stainless steel AISI 304. (Author)

  17. Diffusion-controlled intergranular penetration and embrittlement of copper by liquid bismuth between 300 and 600 Celsius degrees; Penetration intergranulaire fragilisante du cuivre par le bismuth liquide: identification de la cinetique et du mecanisme de type diffusionnel entre 300 et 600 deg

    Energy Technology Data Exchange (ETDEWEB)

    Laporte, V

    2005-02-15

    Hybrid reactors are a new concept for energy production and nuclear waste treatment. Among other requirements, structural materials have to withstand liquid metal embrittlement. This thesis aimed therefore to identify the controlling mechanism for the intergranular embrittlement of copper in contact with liquid bismuth. Scanning electron microscopy, Auger electron spectroscopy, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy have been used to analyze fracture surfaces of both copper polycrystals and a copper bicrystal (symmetric tilt boundary 50 degrees <100>). These analyses reveal both parabolic intergranular penetration kinetics and a maximal intergranular bismuth concentration that is less than two monolayers equivalent. These two results allow us to identify grain boundary diffusion as the controlling mechanism for the intergranular penetration of copper by liquid bismuth between 300 and 600 Celsius degrees, showing the absence of perfect grain boundary wetting. (author)

  18. Fracture characteristics of uranium alloys by scanning electron microscopy

    International Nuclear Information System (INIS)

    Koger, J.W.; Bennett, R.K. Jr.

    1976-10-01

    The fracture characteristics of uranium alloys were determined by scanning electron microscopy. The fracture mode of stress-corrosion cracking (SCC) of uranium-7.5 weight percent niobium-2.5 weight percent zirconium (Mulberry) alloy, uranium--niobium alloys, and uranium--molybdenum alloys in aqueous chloride solutions is intergranular. The SCC fracture surface of the Mulberry alloy is characterized by very clean and smooth grain facets. The tensile-overload fracture surfaces of these alloys are characteristically ductile dimple. Hydrogen-embrittlement failures of the uranium alloys are brittle and the fracture mode is transgranular. Fracture surfaces of the uranium-0.75 weight percent titanium alloys are quasi cleavage

  19. Towards modeling intergranular stress corrosion cracks on grain size scales

    International Nuclear Information System (INIS)

    Simonovski, Igor; Cizelj, Leon

    2012-01-01

    Highlights: ► Simulating the onset and propagation of intergranular cracking. ► Model based on the as-measured geometry and crystallographic orientations. ► Feasibility, performance of the proposed computational approach demonstrated. - Abstract: Development of advanced models at the grain size scales has so far been mostly limited to simulated geometry structures such as for example 3D Voronoi tessellations. The difficulty came from a lack of non-destructive techniques for measuring the microstructures. In this work a novel grain-size scale approach for modelling intergranular stress corrosion cracking based on as-measured 3D grain structure of a 400 μm stainless steel wire is presented. Grain topologies and crystallographic orientations are obtained using a diffraction contrast tomography, reconstructed within a detailed finite element model and coupled with advanced constitutive models for grains and grain boundaries. The wire is composed of 362 grains and over 1600 grain boundaries. Grain boundary damage initialization and early development is then explored for a number of cases, ranging from isotropic elasticity up to crystal plasticity constitutive laws for the bulk grain material. In all cases the grain boundaries are modeled using the cohesive zone approach. The feasibility of the approach is explored.

  20. Postirradiation fracture toughness of Inconel X-750

    International Nuclear Information System (INIS)

    Mills, W.J.

    1983-01-01

    The effect of fast-neutron irradiation on the fracture toughness response of Inconel X-750 was characterized at 427 deg C using the J-R curve technique. Irradiation exposures ranging from 3 to 16 displacements per atom resulted in a reduction in Jsub(Ic) from 130 to 76 kJ/m 2 and a reduction in tearing modulus from 32 to 2.6. Postirradiation fractographic examination revealed that an intergranular fracture mechanism was dominant, in contrast to the extensive transgranular cracking mode found on unirradiated fracture surfaces. The enhanced intergranular failure observed after irradiation was caused by extensive heterogeneous slip in a matrix that was greatly strengthened by an irradiation-induced dislocation substructure. Specifically, intense planar slip bands impinged on the grain boundaries and generated large stress concentrations. Since the stress concentrations could not be relaxed by the hardened matrix, the grain boundaries 'unzipped' readily, resulting in the low toughness and tearing resistance. (author)

  1. The relationship between observed stress corrosion cracking fracture morphology and microstructure in Alloy 600

    International Nuclear Information System (INIS)

    Symons, D.M.; Burke, M.G.; Foster, J.P.

    1997-01-01

    Microstructure is known to influence the stress corrosion cracking (SCC) behavior of Alloy 600 in both hydrogenated water and steam environments. This study evaluated the relative SCC response of a single heat of Alloy 600 as a function of microstructure in a hydrogenated doped-steam environment. The 400 C doped-steam environment was selected for the SCC tests to accelerate cracking. The material was evaluated in three conditions: (1) as-received (2) as-annealed, and (3) as-annealed + 26% deformation. Microstructural characterization was performed using analytical electron microscopy (AEM) techniques for the evaluation of carbide type and morphology, and general structure. Constant displacement (bolt-loaded) compact tension specimens were used to induce SCC. The as-annealed and as-annealed plus cold worked samples had two fracture morphologies: a rough intergranular SCC fracture morphology and a smooth intergranular fracture morphology. The SCC fracture in the as-received specimens was characterized by a classic intergranular morphology at low magnification, consistent with the microstructural evaluation of cross-sectional metallographic samples. More detailed examination revealed a pseudo-intergranular fracture morphology. This pseudo-intergranular morphology appears to be comprised of very fine cleavage-like microfacets. These observations may assist in understanding the difference in SCC fracture morphologies as reported in the open literature

  2. Atomistic Structure, Strength, and Kinetic Properties of Intergranular Films in Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Garofalini, Stephen H

    2015-01-08

    Intergranular films (IGFs) present in polycrystalline oxide and nitride ceramics provide an excellent example of nanoconfined glasses that occupy only a small volume percentage of the bulk ceramic, but can significantly influence various mechanical, thermal, chemical, and optical properties. By employing molecular dynamics computer simulations, we have been able to predict structures and the locations of atoms at the crystal/IGF interface that were subsequently verified with the newest electron microscopies. Modification of the chemistry of the crystal surface in the simulations provided the necessary mechanism for adsorption of specific rare earth ions from the IGF in the liquid state to the crystal surface. Such results had eluded other computational approaches such as ab-initio calculations because of the need to include not only the modified chemistry of the crystal surfaces but also an accurate description of the adjoining glassy IGF. This segregation of certain ions from the IGF to the crystal caused changes in the local chemistry of the IGF that affected fracture behavior in the simulations. Additional work with the rare earth ions La and Lu in the silicon oxynitride IGFs showed the mechanisms for their different affects on crystal growth, even though both types of ions are seen adhering to a bounding crystal surface that would normally imply equivalent affects on grain growth.

  3. Intergranular stress corrosion cracking of low alloy and carbon steels in high temperature pure water

    International Nuclear Information System (INIS)

    Tsubota, M.; Sakamoto, H.; Tsuzuki, R.

    1993-01-01

    Stress corrosion cracking (SCC) behavior of low alloy steels (A508 and SNCM630) and a carbon steel (SGV480) in high temperature water has been examined with relation to the heat treatment condition, including a long time aging, and the mechanical properties. Intergranular stress corrosion cracking (IGSCC) as observed in the highly hardened specimens, and there was observed in the highly hardened specimens, and there was observed in the highly hardened specimens, and there was observed a close relationship between hardness and SCC susceptibility. From the engineering point of view, it was concluded that adequate SR (stress relief) or tempering heat treatment is necessary to avoid the IGSCC of the welded structures made of low alloy and carbon steels. A508 heat treated with specified quench and temper did not show the SCC susceptibility, even after aging 10000 hours at 350, 400 and 450 degrees C. Tensile properties corresponding to the critical hardness for SSC susceptibility coincided with the values at the 'necking point' in the true stress-strain curve. Ductile-brittle transition observed in the fracture toughness test also occurred at around the critical hardness for SCC susceptibility. Therefore, it was conjectured that the limitation of plasticity was an absolute cause for the SCC susceptibility of the steels

  4. Grain-boundary microchemistry and intergranular cracking of irradiated austenitic stainless steels

    International Nuclear Information System (INIS)

    Chung, H.M.; Ruther, W.E.; Sanecki, J.E.; Kassner, T.F.

    1993-01-01

    Constant-extension-rate tensile tests and grain-boundary analysis by Auger electron spectroscopy were conducted on high and commercial-purity (HP and CP) Type 304 stainless steel (SS) specimens from irradiated boiling-water reactor (BWR) components to identify the mechanisms of irradiation-assisted stress corrosion cracking (IASCC). Contrary to previous beliefs, susceptibility to intergranular fracture could not be correlated with radiation-induced segregation of impurities such as Si, P, C, or S, but a correlation was obtained with grain-boundary Cr concentration, indicating a role for Cr depletion. Detailed analysis of grain-boundary chemistry was conducted on BWR neutron absorber tubes that were fabricated from two similar heats of HP Type 304 SS of virtually identical bulk chemical composition but exhibiting a significant difference in susceptibility to IASCC after irradiation to ∼2 x 10 21 n/cm 2 (E > 1 MeV). Grain-boundary concentrations of Cr Ni, Si, P, S, and C of the cracking-resistant and -susceptible HP heats were virtually identical. However, grain boundaries of the cracking-resistant material contained less N and more B and Li than those of the cracking-susceptible material. This observation indicates that, besides the deleterious effect of grain-boundary Cr depletion, a synergism between grain-boundary segregation of N and B and transmutation to H and Li plays an important role in IASCC

  5. A phenomenological variational multiscale constitutive model for intergranular failure in nanocrystalline materials

    KAUST Repository

    Siddiq, A.

    2013-09-01

    We present a variational multiscale constitutive model that accounts for intergranular failure in nanocrystalline fcc metals due to void growth and coalescence in the grain boundary region. Following previous work by the authors, a nanocrystalline material is modeled as a two-phase material consisting of a grain interior phase and a grain boundary affected zone (GBAZ). A crystal plasticity model that accounts for the transition from partial dislocation to full dislocation mediated plasticity is used for the grain interior. Isotropic porous plasticity model with further extension to account for failure due to the void coalescence was used for the GBAZ. The extended model contains all the deformation phases, i.e. elastic deformation, plastic deformation including deviatoric and volumetric plasticity (void growth) followed by damage initiation and evolution due to void coalescence. Parametric studies have been performed to assess the model\\'s dependence on the different input parameters. The model is then validated against uniaxial loading experiments for different materials. Lastly we show the model\\'s ability to predict the damage and fracture of a dog-bone shaped specimen as observed experimentally. © 2013 Elsevier B.V.

  6. Microstructure and intergranular corrosion of the austenitic stainless steel 1.4970

    International Nuclear Information System (INIS)

    Terada, Maysa; Saiki, Mitiko; Costa, Isolda; Padilha, Angelo Fernando

    2006-01-01

    The precipitation behaviour of the DIN 1.4970 steel and its effect on the intergranular corrosion resistance were studied. Time-temperature-precipitation diagrams for the secondary phases (Ti, Mo)C (Cr, Fe, Mo, Ni) 23 C 6 and (Cr, Fe) 2 B are presented and representative samples have been selected for corrosion studies. The susceptibility to intergranular corrosion of the samples was evaluated using the double loop electrochemical potentiokinetic reactivation technique. The results showed that the solution-annealed samples and those aged at 1173 K did not present susceptibility to intergranular corrosion, whereas aging treatment from 873 to 1073 K resulted in small susceptibility to intergranular attack that decreased with aging temperature. The preferential formation of (Ti, Mo)C at higher aging temperatures comparatively to M 23 C 6 , retained the chromium in solid solution preventing steel sensitization and, consequently, intergranular corrosion

  7. Investigation of intergranular corrosion resistance of Cr16Ni25NMo6 steel

    International Nuclear Information System (INIS)

    Kamenev, Yu.B.; Nazarov, A.A.; Kuusk, L.V.; Majdeburova, T.F.

    1990-01-01

    The effect of 08Kh16N25AM6 steel susceptibility to intergranular corrosion on its intergranular cracking resistance in high-temperature water is investigated. In addition, the performed tests point to the susceptibility of sensibilized Kh16N25AM6 steel to intergranular corrosion in media simulating an agressive environment of power generation equipment; the latter requires a strict control over the resistance of weld joints of the above steel to intergranular corrosion. It is shown that Kh16N25AM6 type steel in sensibilized state is susceptible to intercrystalline corrosion cracking in high-temperature water which correlates with its susceptibility to intergranular corrosion established by AM GOST 6032-84 and potentiodynamic reactivation methods

  8. In-situ observation of intergranular stress corrosion cracking in AA2024-T3 under constant load conditions

    International Nuclear Information System (INIS)

    Liu Xiaodong; Frankel, G.S.; Zoofan, B.; Rokhlin, S.I.

    2007-01-01

    A specially designed setup was used to apply a constant load to a thin sheet sample of AA2024-T3 and, using microfocal X-ray radiography, to observe in situ the resulting intergranular stress corrosion cracking (IGSCC) from the exposed edge of the sample. The growth of and competition between multiple IGSCC sites was monitored. In many experiments twin cracks initiated close to each other. Furthermore, the deepest crack at the beginning of every experiment was found to slow or stop growing, and was then surpassed by another crack that eventually penetrated through the sample. These observations cannot be explained by the theory of fracture mechanics in inert environments. The possible mechanisms underlying the competition between cracks are discussed

  9. Mechanistic differences between transgranular and intergranular stress corrosion cracking

    International Nuclear Information System (INIS)

    Serebrinsky, Santiago A.; Galvele, Jose R.

    2000-01-01

    Constant extension rate tests (CERT or CSRT) with the strain rate (SR) covering a 7 orders of magnitude range were applied to the study of many systems. In particular, the kinetics of SCC were measured via the stress corrosion (SCC) crack propagation rate (CPR). The main experimental findings are: a) increasing SR produces a monotonic (logarithmic) increase in CPR; b) the slopes α in log CPR vs. log SR plots take distinct values depending on the morphology: intergranular (IG) cracks are more steeply accelerated by SR than transgranular (TG), with α lG =0.4 to 0.7 and α TG =0.2 to 0.3; c) an increase in SR only shifts the log CPR vs. potential curves to higher CPR values, without changing its shape. Quantitative evaluation shows that dislocations piled-up at grain boundaries may combine with the surface mobility mechanism to give the experimental results. (author)

  10. Two-phase flow experiments through intergranular stress corrosion cracks

    International Nuclear Information System (INIS)

    Collier, R.P.; Norris, D.M.

    1984-01-01

    Experimental studies of critical two-phase water flow, through simulated and actual intergranular stress corrosion cracks, were performed to obtain data to evaluate a leak flow rate model and investigate acoustic transducer effectiveness in detecting and sizing leaks. The experimental program included a parametric study of the effects of crack geometry, fluid stagnation pressure and temperature, and crack surface roughness on leak flow rate. In addition, leak detection, location, and leak size estimation capabilities of several different acoustic transducers were evaluated as functions of leak rate and transducer position. This paper presents flow rate data for several different cracks and fluid conditions. It also presents the minimum flows rate detected with the acoustic sensors and a relationship between acoustic signal strength and leak flow rate

  11. Estimation of flow rates through intergranular stress corrosion cracks

    International Nuclear Information System (INIS)

    Collier, R.P.; Norris, D.M.

    1984-01-01

    Experimental studies of critical two-phase water flow, through simulated and actual intergranular stress corrosion cracks, were performed to obtain data to evaluate a leak flow rate model and investigate acoustic transducer effectiveness in detecting and sizing leaks. The experimental program included a parametric study of the effects of crack geometry, fluid stagnation pressure and temperature, and crack surface roughness on leak flow rate. In addition, leak detection, location, and leak size estimation capabilities of several different acoustic transducers were evaluated as functions of leak rate and transducer position. This paper presents flow rate data for several different cracks and fluid conditions. It also presents the minimum flow rate detected with the acoustic sensors and a relationship between acoustic signal strength and leak flow rate

  12. Martensitic transformation in an intergranular corrosion area of austenitic stainless steel during thermal cycling

    International Nuclear Information System (INIS)

    La Fontaine, Alexandre; Yen, Hung-Wei; Trimby, Patrick; Moody, Steven; Miller, Sarah; Chensee, Martin; Ringer, Simon; Cairney, Julie

    2014-01-01

    An oxidation-assisted martensitic phase transformation was observed in an austenitic stainless steel after thermal cycling up to 970 °C in air in a solar thermal steam reformer. The intergranular corrosion areas were investigated by electron backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD) and transmission electron microscopy (TEM). The structural-and-chemical maps revealed that within intergranular corrosion areas this martensitic transformation primarily occurs in oxidation-induced chromium-depleted zones, rather than due to only sensitization. This displacive transformation may also play a significant role in the rate at which intergranular corrosion takes place

  13. Weak Frictional Healing as Controlled by Intergranular Pressure Solution

    Science.gov (United States)

    He, C.

    2017-12-01

    Unstable fault slips due to velocity weakening requires a frictional healing effect that is stronger than the instantaneous rate effect. Based on a previous analytical result regarding the healing effect at spherical contacts by intergranular pressure solution (He et al., 2013), we extend the analysis to incorporate the full range of dilatancy angles from π/6 to -π/6, covering uphill and downhill situations of many contacts with different dilatancy angles. Assuming that both healing effect (parameter b) and instantaneous rate effect (parameter a) are controlled by intergranular pressure solution, and averaging over the whole range of dilatancy angle, our analysis derives each of the two effects as a function of temperature. The result shows velocity weakening for friction coefficient>0.274. As hydrothermal conditions are important for deep portion of actual fault zones, the strength of velocity weakening is of interest when the related faulting behavior is concerned. As a measure of the strength of velocity weakening, the derived ratio b/a fully controlled by pressure solution shows an upper bound of 1.22. Data analyses in previous studies on plagioclase (He et al., 2013) and oceanic basalt (Zhang and He, 2017) shows a range of b/a =1.05-1.2, consistent with the analytical result. The valuesrate effect, which reduces b/a to levels below the upper bound. These values are significantly less than in dry experiments on granite by Mitchell et al.(2016), where b/a ranges from 1.54-2.59 as inferred by reanalyzing their stick-slip data at temperatures of 20°C, 500°C and 600°C. Comparison between the two ranges of b/a helps understand the dominant mechanism of frictional healing at contacts, especially under hydrothermal conditions in fault zones. For comparable ratios of system stiffness to the critical value, numerical simulations with a single-degree-of-freedom system show that a smaller b/a significantly reduces the peak slip velocity as a result of reduced period

  14. Imaging and thickness measurement of amorphous intergranular films using TEM

    International Nuclear Information System (INIS)

    MacLaren, I.

    2004-01-01

    Fresnel fringe analysis is shown to be unreliable for grain boundaries in yttrium-doped alumina: the determined thicknesses do not agree well with those measured from high resolution transmission electron microscopy (HRTEM), the asymmetry between under- and overfocus is very large, and Fresnel fringes are sometimes shown at boundaries which contain no amorphous film. An alternative approach to the analysis of HRTEM images of grain boundary films is demonstrated: Fourier filtering is used to remove the lattice fringes from the image thereby significantly enhancing the visibility of the intergranular films. The apparent film thickness shows a discrepancy between measurements from the original HRTEM image and the filtered image. It was shown that fringe delocalisation and diffuseness of the amorphous/crystalline interfaces will lead to a significant underestimate of the thickness in unprocessed HRTEM images. In contrast to this, the average thickness can be much more accurately measured from the Fourier-filtered image, provided the boundary is oriented accurately edge-on

  15. Electromigration of intergranular voids in metal films for microelectronic interconnects

    CERN Document Server

    Averbuch, A; Ravve, I

    2003-01-01

    Voids and cracks often occur in the interconnect lines of microelectronic devices. They increase the resistance of the circuits and may even lead to a fatal failure. Voids may occur inside a single grain, but often they appear on the boundary between two grains. In this work, we model and analyze numerically the migration and evolution of an intergranular void subjected to surface diffusion forces and external voltage applied to the interconnect. The grain-void interface is considered one-dimensional, and the physical formulation of the electromigration and diffusion model results in two coupled fourth-order one-dimensional time-dependent PDEs. The boundary conditions are specified at the triple points, which are common to both neighboring grains and the void. The solution of these equations uses a finite difference scheme in space and a Runge-Kutta integration scheme in time, and is also coupled to the solution of a static Laplace equation describing the voltage distribution throughout the grain. Since the v...

  16. A phenomenological variational multiscale constitutive model for intergranular failure in nanocrystalline materials

    KAUST Repository

    Siddiq, A.; El Sayed, Tamer S.

    2013-01-01

    We present a variational multiscale constitutive model that accounts for intergranular failure in nanocrystalline fcc metals due to void growth and coalescence in the grain boundary region. Following previous work by the authors, a nanocrystalline

  17. Testing of intergranular and pitting corrosion in sensitized welded joints of austenitic stainless steel

    Directory of Open Access Journals (Sweden)

    Bore V. Jegdic

    2017-06-01

    Full Text Available Pitting corrosion resistance and intergranular corrosion of the austenitic stainless steel X5Cr Ni18-10 were tested on the base metal, heat affected zone and weld metal. Testing of pitting corrosion was performed by the potentiodynamic polarization method, while testing of intergranular corrosion was performed by the method of electrochemical potentiokinetic reactivation with double loop. The base metal was completely resistant to intergranular corrosion, while the heat affected zone showed a slight susceptibility to intergranular corrosion. Indicators of pitting corrosion resistance for the weld metal and the base metal were very similar, but their values are significantly higher than the values for the heat affected zone. This was caused by reduction of the chromium concentration in the grain boundary areas in the heat affected zone, even though the carbon content in the examined stainless steel is low (0.04 wt. % C.

  18. Proceedings: 1991 EPRI workshop on secondary-side intergranular corrosion mechanisms

    International Nuclear Information System (INIS)

    Partridge, M.J.; Zemitis, W.S.

    1992-08-01

    A workshop on ''Secondary-Side Intergranular Corrosion Mechanisms'' was organized by EPRI as an effort to give those working in this area an opportunity to share their results, ideas, and plans. Topics covered included: (1) caustic induced intergranular attack/stress corrosion cracking (IGA/IGSCC), (2) plant experience, (3) boric acid as an IGA/IGSCC remedial measure, (4) lead induced IGA/IGSCC, and (5) acid induced IGA/IGSCC

  19. A study on the fractures of iodine induced stress corrosion cracking of new zirconium alloys

    International Nuclear Information System (INIS)

    Peng Qian; Zhao Wenjin; Li Weijun; Tang Zhenghua; Heng Xuemei

    2005-10-01

    The morphology and chemical compositions of I-SCC fractures of new zirconium alloys were investigated by SEM and EDXA. The feature on fracture surface for I-SCC samples, such as corrosion products, the secondary cracking, intergranular cracking and pseudo-cleavage transgranular cracking, have been observed. And the fluting, the typical characteristic of I-SCC also has been found. Intergranular cracking is visible at crack initiation stage and transgranular cracking is distinguished at crack propagation stage. The corrosion products are mainly composed of Zr and O; and I can be detected on the local pseudocleavage zone. The most of grooves on the fractures of relieved-stress annealing samples are parallel with the roll plane. The intergranular cracking in relieved-stress annealing samples is not obvious. When the test temperature increases, the activity of iodine increases and the stress on crack tip is easier to be released, thus the corrosion products on fracture also increase and intergranular cracking is visible. The partial pressure of iodine influents the thickness of corrosion products, and intergranular cracking is easier to be found when iodine partial pressure is high enough. (authors)

  20. Fracture Mechanics

    International Nuclear Information System (INIS)

    Jang, Dong Il; Jeong, Gyeong Seop; Han, Min Gu

    1992-08-01

    This book introduces basic theory and analytical solution of fracture mechanics, linear fracture mechanics, non-linear fracture mechanics, dynamic fracture mechanics, environmental fracture and fatigue fracture, application on design fracture mechanics, application on analysis of structural safety, engineering approach method on fracture mechanics, stochastic fracture mechanics, numerical analysis code and fracture toughness test and fracture toughness data. It gives descriptions of fracture mechanics to theory and analysis from application of engineering.

  1. Double coating protection of Nd–Fe–B magnets: Intergranular phosphating treatment and copper plating

    International Nuclear Information System (INIS)

    Zheng, Jingwu; Chen, Haibo; Qiao, Liang; Lin, Min; Jiang, Liqiang; Che, Shenglei; Hu, Yangwu

    2014-01-01

    In this work, a double coating protection technique of phosphating treatment and copper plating was made to improve the corrosion resistance of sintered Nd–Fe–B magnets. In other words, the intergranular region of sintered Nd–Fe–B is allowed to generate passive phosphate conversion coating through phosphating treatment, followed by the copper coating on the surface of sintered Nd–Fe–B. The morphology and corrosion resistance of the phosphated sintered Nd–Fe–B were observed using SEM and electrochemical method respectively. The phosphate conversion coating was formed more preferably on the intergranular region of sintered Nd–Fe–B than on the main crystal region; just after a short time of phosphating treatment, the intergranular region of sintered Nd–Fe–B has been covered by the phosphate conversion coating and the corrosion resistance is significantly improved. With the synergistic protection of the intergranular phosphorization and the followed copper electrodeposition, the corrosion resistance of the sintered Nd–Fe–B is significantly better than that with a single phosphate film or single plating protection. - Highlights: • We combined intergranular phosphating and copper plating to protect Nd–Fe–B. • The phosphate conversion coating was formed preferably on the intergranular region. • The phosphating coating can obviously improve the corrosion resistance of Nd–Fe–B. • The corrosion resistance of Nd–Fe–B was improved by double coating protection

  2. Double coating protection of Nd–Fe–B magnets: Intergranular phosphating treatment and copper plating

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jingwu; Chen, Haibo; Qiao, Liang [College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014 (China); Lin, Min [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering Chinese Academy of Science, Ningbo 315201 (China); Jiang, Liqiang; Che, Shenglei [College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014 (China); Hu, Yangwu, E-mail: 346648086@qq.com [College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014 (China); Wenzhou Institute of Industry and Science, Wenzhou 325000 (China)

    2014-12-15

    In this work, a double coating protection technique of phosphating treatment and copper plating was made to improve the corrosion resistance of sintered Nd–Fe–B magnets. In other words, the intergranular region of sintered Nd–Fe–B is allowed to generate passive phosphate conversion coating through phosphating treatment, followed by the copper coating on the surface of sintered Nd–Fe–B. The morphology and corrosion resistance of the phosphated sintered Nd–Fe–B were observed using SEM and electrochemical method respectively. The phosphate conversion coating was formed more preferably on the intergranular region of sintered Nd–Fe–B than on the main crystal region; just after a short time of phosphating treatment, the intergranular region of sintered Nd–Fe–B has been covered by the phosphate conversion coating and the corrosion resistance is significantly improved. With the synergistic protection of the intergranular phosphorization and the followed copper electrodeposition, the corrosion resistance of the sintered Nd–Fe–B is significantly better than that with a single phosphate film or single plating protection. - Highlights: • We combined intergranular phosphating and copper plating to protect Nd–Fe–B. • The phosphate conversion coating was formed preferably on the intergranular region. • The phosphating coating can obviously improve the corrosion resistance of Nd–Fe–B. • The corrosion resistance of Nd–Fe–B was improved by double coating protection.

  3. Micromechanical studies of cyclic creep fracture under stress controlled loading

    DEFF Research Database (Denmark)

    van der Giessen, Erik; Tvergaard, Viggo

    1996-01-01

    is based on numerical unit cell analyses for a planar polycrystal model with the grains and grain boundaries modeled individually, in order to investigate the interactions between the mechanisms involved and to account for the build-up of residual stress fields during cycling. The behaviour of a limiting......This paper deals with a study of intergranular failure by creep cavitation under stress-controlled cyclic loading conditions. Loading is assumed to be slow enough that diffusion and creep mechanisms (including grain boundary sliding) dominate, leading to intergranular creep fracture. This study...

  4. Cohesive zone modeling of intergranular cracking in polycrystalline aggregates

    International Nuclear Information System (INIS)

    Simonovski, Igor; Cizelj, Leon

    2015-01-01

    Highlights: • Alternative approach to cohesive elements is proposed: cohesive-zone contact. • Applicability to measured and simulated grain structures is demonstrated. • Normal and normal/shear separation as a damage initialization is explored. • Normal/shear damage initialization significantly reduces ductility. • Little difference in Voronoi aggregate size on macroscopic response. - Abstract: Understanding and controlling early damage initiation and evolution are amongst the most important challenges in nuclear power plants, occurring in ferritic, austenitic steels and nickel based alloys. In this work a meso-scale approach to modeling initiation and evolution of early intergranular cracking is presented. This damage mechanism is present in a number of nuclear power plant components and depends on the material (e.g. composition, heat treatment, microstructure), environment and load. Finite element modeling is used to explicitly model the microstructure – both the grains and the grain boundaries. Spatial Voronoi tessellation is used to obtain the grain topology. In addition, measured topology of a 0.4 mm stainless steel wire is used. Anisotropic elasticity and crystal plasticity are used as constitutive laws for the grains. Grain boundaries are modeled using the cohesive zone approach. Different modeling assumptions/parameters are evaluated against the numerical stability criteria. The biggest positive contribution to numerical stability is the use of cohesive-type contact instead of cohesive elements. A small amount of viscous regularization should be also used along with the addition of a small amount of viscous forces to the global equilibrium equations. Two cases of grain boundary damage initiation are explored: (1) initiation due to normal separation and (2) initiation due to a combination of normal and shear separation. The second criterion significantly decreases the ductility of an aggregate and slightly improves the numerical stability

  5. Ultrasonic inspection reliability for intergranular stress corrosion cracks

    Energy Technology Data Exchange (ETDEWEB)

    Heasler, P G; Taylor, T T; Spanner, J C; Doctor, S R; Deffenbaugh, J D [Pacific Northwest Lab., Richland, WA (USA)

    1990-07-01

    A pipe inspection round robin entitled Mini-Round Robin'' was conducted at Pacific Northwest Laboratory from May 1985 through October 1985. The research was sponsored by the US Nuclear Regulatory Commission, Office of Nuclear Regulatory Research under a program entitled Evaluation and Improvement of NDE Reliability for Inservice Inspection of Light Water Reactors.'' The Mini-Round Robin (MRR) measured the intergranular stress corrosion (GSC) crack detection and sizing capabilities of inservice inspection (ISI) inspectors that had passed the requirements of IEB 83-02 and the Electric Power Research Institute (EPRI) sizing training course. The MRR data base was compared with an earlier Pipe Inspection Round Robin (PIRR) that had measured the performance of inservice inspection prior to 1982. Comparison of the MRR and PIRR data bases indicates no significant change in the inspection capability for detecting IGSCC. Also, when comparing detection of long and short cracks, no difference in detection capability was measured. An improvement in the ability to differentiate between shallow and deeper IGSCC was found when the MRR sizing capability was compared with an earlier sizing round robin conducted by the EPRI. In addition to the pipe inspection round robin, a human factors study was conducted in conjunction with the Mini-Round Robin. The most important result of the human factors study is that the Relative Operating Characteristics (ROC) curves provide a better methodology for describing inspector performance than only probability of detection (POD) or single-point crack/no crack data. 6 refs., 55 figs., 18 tabs.

  6. Fracture in Soft Materials

    DEFF Research Database (Denmark)

    Hassager, Ole

    Fracture is a phenomenon that is generally associated with solids. A key element in fracture theory is the so-called weakest link idea that fracture initiates from the largest pre-existing material imperfection. However, recent work has demonstrated that fracture can also happen in liquids, where...... surface tension will act to suppress such imperfections. Therefore, the weakest link idea does not seem immediately applicable to fracture in liquids. This presentation will review fracture in liquids and argue that fracture in soft liquids is a material property independent of pre-existing imperfections....... The following questions then emerge: What is the material description needed to predict crack initiation, crack speed and crack shape in soft materials and liquids....

  7. Identification of modes of fracture in a 2618-T6 aluminum alloy using stereophotogrammetry

    Energy Technology Data Exchange (ETDEWEB)

    Salas Zamarripa, A., E-mail: a.salaszamarripa@gmail.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon. Av. Universidad S/N, Ciudad Universitaria, C.P. 66451, Apartado Postal 076 Suc. ' F' San Nicolas de los Garza, N.L. (Mexico); Pinna, C.; Brown, M.W. [Department of Mechanical Engineering, University of Sheffield. Sir Frederick Mappin Building, Mappin Street, Sheffield, S1 3JD (United Kingdom); Mata, M.P. Guerrero; Morales, M. Castillo; Beber-Solano, T.P. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon. Av. Universidad S/N, Ciudad Universitaria, C.P. 66451, Apartado Postal 076 Suc. ' F' San Nicolas de los Garza, N.L. (Mexico)

    2011-12-15

    The identification and the development of a quantification technique of the modes of fracture in fatigue fracture surfaces of a 2618-T6 aluminum alloy were developed during this research. Fatigue tests at room and high temperature (230 Degree-Sign C) were carried out to be able to compare the microscopic fractographic features developed by this material under these testing conditions. The overall observations by scanning electron microscopy (SEM) of the fracture surfaces showed a mixture of transgranular and ductile intergranular fracture. The ductile intergranular fracture contribution appears to be more significant at room temperature than at 230 Degree-Sign C. A quantitative methodology was developed to identify and to measure the contribution of these microscopic fractographic features. The technique consisted of a combination of stereophotogrammetry and image analysis. Stereo-pairs were randomly taken along the crack paths and were then analyzed using the profile module of MeX software. The analysis involved the 3-D surface reconstruction, the trace of primary profile lines in both vertical and horizontal directions within the stereo-pair area, the measurements of the contribution of the modes of fracture in each profile, and finally, the calculation of the average contribution in each stereo-pair. The technique results confirmed a higher contribution of ductile intergranular fracture at room temperature than at 230 Degree-Sign C. Moreover, there was no indication of a direct relationship between this contribution and the strain amplitudes range applied during the fatigue testing. - Highlights: Black-Right-Pointing-Pointer Stereophotogrammetry and image analysis as a measuring tool of modes of fracture in fatigue fracture surfaces. Black-Right-Pointing-Pointer A mixture of ductile intergranular and transgranular fracture was identified at room temperature and 230 Degree-Sign C testing. Black-Right-Pointing-Pointer Development of a quantitative methodology to

  8. Identification of modes of fracture in a 2618-T6 aluminum alloy using stereophotogrammetry

    International Nuclear Information System (INIS)

    Salas Zamarripa, A.; Pinna, C.; Brown, M.W.; Mata, M.P. Guerrero; Morales, M. Castillo; Beber-Solano, T.P.

    2011-01-01

    The identification and the development of a quantification technique of the modes of fracture in fatigue fracture surfaces of a 2618-T6 aluminum alloy were developed during this research. Fatigue tests at room and high temperature (230 °C) were carried out to be able to compare the microscopic fractographic features developed by this material under these testing conditions. The overall observations by scanning electron microscopy (SEM) of the fracture surfaces showed a mixture of transgranular and ductile intergranular fracture. The ductile intergranular fracture contribution appears to be more significant at room temperature than at 230 °C. A quantitative methodology was developed to identify and to measure the contribution of these microscopic fractographic features. The technique consisted of a combination of stereophotogrammetry and image analysis. Stereo-pairs were randomly taken along the crack paths and were then analyzed using the profile module of MeX software. The analysis involved the 3-D surface reconstruction, the trace of primary profile lines in both vertical and horizontal directions within the stereo-pair area, the measurements of the contribution of the modes of fracture in each profile, and finally, the calculation of the average contribution in each stereo-pair. The technique results confirmed a higher contribution of ductile intergranular fracture at room temperature than at 230 °C. Moreover, there was no indication of a direct relationship between this contribution and the strain amplitudes range applied during the fatigue testing. - Highlights: ► Stereophotogrammetry and image analysis as a measuring tool of modes of fracture in fatigue fracture surfaces. ► A mixture of ductile intergranular and transgranular fracture was identified at room temperature and 230 °C testing. ► Development of a quantitative methodology to obtain the percentage of modes of fracture within the fracture surface.

  9. Computational simulation for creep fracture properties taking microscopic mechanism into account

    International Nuclear Information System (INIS)

    Tabuchi, Masaaki

    2003-01-01

    Relationship between creep crack growth rate and microscopic fracture mechanism i.e., wedge-type intergranular, transgranular and cavity-type intergranular crack growth, has been investigated. The growth rate of wedge-type and transgranular creep crack could be characterized by creep ductility. Creep damages formed ahead of the cavity-type crack tip accelerated the crack growth rate. Based on the experimental results, FEM code that simulates creep crack growth has been developed by taking the fracture mechanism into account. The effect of creep ductility and void formation ahead of the crack tip on creep crack growth behavior could be simulated. (author)

  10. Microstructure and temperature dependence of intergranular strains on diffractometric macroscopic residual stress analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, J.N., E-mail: Julia.Wagner@kit.edu [KNMF, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Hofmann, M. [Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II), TU München, Lichtenbergstr. 1, 85747 Garching (Germany); Wimpory, R. [Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin Wannsee (Germany); Krempaszky, C. [Christian-Doppler-Labor für Werkstoffmechanik von Hochleistungslegierungen, TU München, Boltzmannstr. 15, 85747 Garching (Germany); Lehrstuhl für Werkstoffkunde und Werkstoffmechanik, TU München, Boltzmannstr. 15, 85747 Garching (Germany); Stockinger, M. [Böhler Schmiedetechnik GmbH and Co KG, Mariazeller Straße 25, 8605 Kapfenberg (Austria)

    2014-11-17

    Knowledge of the macroscopic residual stresses in components of complex high performance alloys is crucial when it comes to considering the safety and manufacturing aspects of components. Diffraction experiments are one of the key methods for studying residual stresses. However a component of the residual strain determined by diffraction experiments, known as microstrain or intergranular residual strain, occurs over the length scale of the grains and thus plays only a minor role for the life time of such components. For the reliable determination of macroscopic strains (with the minimum influence of these intergranular residual strains), the ISO standard recommends the use of particular Bragg reflections. Here we compare the build-up of intergranular strain of two different precipitation hardened IN 718 (INCONEL 718) samples, with identical chemical composition. Since intergranular strains are also affected by temperature, results from room temperature measurement are compared to results at T=550 °C. It turned out that microstructural parameters, such as grain size or type of precipitates, have a larger effect on the intergranular strain evolution than the influence of temperature at the measurement temperature of T=550 °C. The results also show that the choice of Bragg reflections for the diffractometric residual stress analysis is dependent not only on its chemical composition, but also on the microstructure of the sample. In addition diffraction elastic constants (DECs) for all measured Bragg reflections are given.

  11. Effect of mechanical treatment on intergranular corrosion of 6064 alloy bars

    Science.gov (United States)

    Sláma, P.; Nacházel, J.

    2017-02-01

    Aluminium Al-Mg-Si-type alloys (6xxx-series) exhibit good mechanical properties, formability, weldability and good corrosion resistance in various environments. They often find use in automotive industry and other applications. Some alloys, however, particularly those with higher copper levels, show increased susceptibility to intergranular corrosion. Intergranular corrosion (IGC) is typically related to the formation of microgalvanic cells between cathodic, more noble phases and depleted (precipitate-free) zones along grain boundaries. It is encountered mainly in AlMgSi alloys containing Cu, where it is thought to be related to the formation Q-phase precipitates (Al4Mg8Si7Cu2) along grain boundaries. The present paper describes the effects of mechanical working (extrusion, drawing and straightening) and artificial aging on intergranular corrosion in rods of the 6064 alloy. The resistance to intergranular corrosion was mapped using corrosion tests according to EN ISO 11846, method B. Corrosion tests showed dependence of corrosion type on mechanical processing of the material. Intergranular, pitting and transgranular corrosion was observed. Artificial ageing influenced mainly the depth of the corrosion.

  12. Techniques for intergranular crack formation and assessment in alloy 600 base and alloy 182 weld metals

    International Nuclear Information System (INIS)

    Lee, Tae Hyun; Hwang, Il Soon; Kim, Hong Deok; Kim, Ji Hyun

    2015-01-01

    A technique developed to produce artificial intergranular stress corrosion cracks in structural components was applied to thick, forged alloy 600 base and alloy 182 weld metals for use in the qualification of nondestructive examination techniques for welded components in nuclear power plants. An externally controlled procedure was demonstrated to produce intergranular stress corrosion cracks that are comparable to service-induced cracks in both the base and weld metals. During the process of crack generation, an online direct current potential drop method using array probes was used to measure and monitor the sizes and shapes of the cracks. A microstructural characterization of the produced cracks revealed realistic conformation of the crack faces unlike those in machined notches produced by an electrodischarge machine or simple fatigue loading using a universal testing machine. A comparison with a destructive metallographic examination showed that the characteristics, orientations, and sizes of the intergranular cracks produced in this study are highly reproducible.

  13. Intergranular corrosion of Ti-stabilized 11 wt% Cr ferritic stainless steel for automotive exhaust systems

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Kil [Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, San 31, Pohang 790-784 (Korea, Republic of); Kim, Yeong Ho; Uhm, Sang Ho; Lee, Jong Sub [POSCO Technical Research Center, Pohang, 790-704 (Korea, Republic of); Kim, Kyoo Young [Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, San 31, Pohang 790-784 (Korea, Republic of)], E-mail: kykim@postech.ac.kr

    2009-11-15

    Intergranular corrosion (IGC) of type 409L ferritic stainless steel (FSS) was investigated. A free-exposure corrosion and a double loop electrochemical potentiokinetic reactivation (DL-EPR) tests were conducted to examine IGC of the FSS. IGC occurred in the specimens aged at the temperature range of 400-600 deg. C that has the sensitization nose located around 600 deg. C. The critical I{sub r}/I{sub a} value was determined to be about 0.03 above which IGC occurred. Based on the analysis of the intergranular precipitates by an energy dispersive spectroscopy (EDS) and a transmission electron microscopy (TEM), IGC was induced by the Cr depletion zone formation due to Cr segregation around intergranular TiC.

  14. Microstructure and intergranular corrosion resistance of UNS S17400 (17-4PH) stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Tavares, S.S.M., E-mail: ssmtavares@terra.com.b [Universidade Federal Fluminense - Programa de Pos-graduacao em Engenharia Mecanica (PGMEC), Rua Passo da Patria, 156 - CEP 24210-240 - Niteroi/RJ (Brazil); Silva, F.J. da; Scandian, C. [Universidade Federal do Espirito Santo - Departamento de Engenharia Mecanica - Av. Fernando Ferrrari, 514 - CEP 29075-910 - Vitoria/ES (Brazil); Silva, G.F. da [Universidade Federal Fluminense - Programa de Pos-graduacao em Engenharia Mecanica (PGMEC), Rua Passo da Patria, 156 - CEP 24210-240 - Niteroi/RJ (Brazil); Abreu, H.F.G. de [Universidade Federal do Ceara - Departamento de Engenharia Metalurgica e Materiais - Campus do Pici, Bloco 702 - CEP 60455-760 - Fortaleza/CE (Brazil)

    2010-11-15

    UNS S17400 or 17-4PH is a precipitation hardening martensitic stainless steel with many industrial applications. Quite different mechanical properties can be produced in this material by varying the aging temperature. In this work, the influence of aging temperature on the intergranular corrosion susceptibility was evaluated by electrochemical and metallographic tests. The microstructural features were investigated by X-ray diffraction, optical and scanning electron microscopy. Intergranular chromium carbide precipitation occurs in specimens aged at high temperatures, although NbC carbides were also observed. The results obtained by double loop electrochemical potentiodynamic reactivation tests (DL-EPR) show that the susceptibility to intergranular corrosion resistance increases with the increase of aging temperature. Healing due to Cr diffusion in the 600-650 {sup o}C range was not observed by DL-EPR tests.

  15. Microstructure and intergranular corrosion resistance of UNS S17400 (17-4PH) stainless steel

    International Nuclear Information System (INIS)

    Tavares, S.S.M.; Silva, F.J. da; Scandian, C.; Silva, G.F. da; Abreu, H.F.G. de

    2010-01-01

    UNS S17400 or 17-4PH is a precipitation hardening martensitic stainless steel with many industrial applications. Quite different mechanical properties can be produced in this material by varying the aging temperature. In this work, the influence of aging temperature on the intergranular corrosion susceptibility was evaluated by electrochemical and metallographic tests. The microstructural features were investigated by X-ray diffraction, optical and scanning electron microscopy. Intergranular chromium carbide precipitation occurs in specimens aged at high temperatures, although NbC carbides were also observed. The results obtained by double loop electrochemical potentiodynamic reactivation tests (DL-EPR) show that the susceptibility to intergranular corrosion resistance increases with the increase of aging temperature. Healing due to Cr diffusion in the 600-650 o C range was not observed by DL-EPR tests.

  16. Fracture mechanism of a dispersion-hardened molybdenum alloy with strong structural interfaces

    International Nuclear Information System (INIS)

    Vasil'ev, A.D.; Malashenko, I.S.; Moiseev, V.F.; Pechkovskij, Eh.P.; Sul'zhenko, V.K.; Trefilov, V.I.; AN Ukrainskoj SSR, Kiev. Inst. Ehlektrosvarki)

    1978-01-01

    Fracture mechanism in the two-phase Mo-15wt.%Nb-3.5 vol.% TiN alloy known to be of ''brittle matrix-strong interfaces'' type has been investigated depending on tensile test temperature. Several temperature intervals of fracture have been found, each of them having its own peculiarities. A scheme is suggested for fracture mechanism changes in dispersion-hardened alloys with strong interfaces. At low test temperatures brittle cleavage fracture takes place. With temperature increase fracture mechanisms change in the following way: brittle intergranular fracture; fracture of ''microvoid coalescence'' type; fracture typical for reinforced materials with ductile matrix; intergran laru fracture. Particles of strengthening phase have been shown to play different roles depending on the test temperature in the fracture of the alloys studied

  17. Investigation of intergranular stress corrosion cracking in the fuel pool at Three Mile Island Unit 1

    International Nuclear Information System (INIS)

    Czajkowski, C.J.

    1985-01-01

    An intergranular stress corrosion cracking failure of 304 stainless steel pipe in 2000 ppM B as H 3 BO 3 + H 2 O at 100 0 C has been investigated. Constant extension rate testing has produced an intergranular type failure in material in air. Chemical analysis was performed on both the base metal and weld material, in addition to fractography, EPR testing and optical microscopy in discerning the mode of failure. Various effects of Cl - , O 2 , and MnS are discussed. The results have indicated that the cause of failure was the severe sensitization coupled with probable contamination by S and possibly by Cl ions

  18. The characteristics creep fracture of austenitic stainless steels

    International Nuclear Information System (INIS)

    Monteiro, S.N.; Assis, A.M.C.A.

    1977-05-01

    The characteristics of fracture on creep of two AISI type 316 austenitic stainless steels tested at constant load from 600 to 800 0 C were studied by scanning electron microscopy. The morphological aspects of the fracture were analysed and correllated to the ductility level attained in creep. A marked change from intergranular to transgranular type of fracture was observed in going from 600 to 800 0 C. At 800 0 C on the other hand, the condition for crack nucleation at sigma phase as well as the special conditions of oxidation, are apparently responsible for that same change with the applied stress. (Author) [pt

  19. Cohesive zone model for intergranular slow crack growth in ceramics: influence of the process and the microstructure

    International Nuclear Information System (INIS)

    Romero de la Osa, M; Olagnon, C; Chevalier, J; Estevez, R; Tallaron, C

    2011-01-01

    Ceramic polycrystals are prone to slow crack growth (SCG) which is stress and environmentally assisted, similarly to observations reported for silica glasses. The kinetics of fracture are known to be dependent on the load level, the temperature and the relative humidity. In addition, evidence is available on the influence of the microstructure on the SCG rate with an increase in the crack velocity with decreasing the grain size. Crack propagation takes place beyond a load threshold, which is grain size dependent. We present a cohesive zone model for the intergranular failure process. The methodology accounts for an intrinsic opening that governs the length of the cohesive zone and allows the investigation of grain size effects. A rate and temperature-dependent cohesive model is proposed (Romero de la Osa M, Estevez R et al 2009 J. Mech. Adv. Mater. Struct. 16 623–31) to mimic the reaction–rupture mechanism. The formulation is inspired by Michalske and Freiman's picture (Michalske and Freiman 1983 J. Am. Ceram. Soc. 66 284–8) together with a recent study by Zhu et al (2005 J. Mech. Phys. Solids 53 1597–623) of the reaction–rupture mechanism. The present investigation extends a previous work (Romero de la Osa et al 2009 Int. J. Fracture 158 157–67) in which the problem is formulated. Here, we explore the influence of the microstructure in terms of grain size, their elastic properties and residual thermal stresses originating from the cooling from the sintering temperature down to ambient conditions. Their influence on SCG for static loadings is reported and the predictions compared with experimental trends. We show that the initial stress state is responsible for the grain size dependence reported experimentally for SCG. Furthermore, the account for the initial stresses enables the prediction of a load threshold below which no crack growth is observed: a crack arrest takes place when the crack path meets a region in compression

  20. Intergranular cracking mechanism in baffle former bolt materials for PWR core internals

    Energy Technology Data Exchange (ETDEWEB)

    Yonezawa, Toshio; Arioka, Koji; Kanasaki, Hiroshi; Fujimoto, Koji [Takasago R and D Center, Mitsubishi Heavy Industries Ltd., Takasago, Hyogo (Japan); Ajiki, Kazuhide [Kobe Shipyard and Machinery, Mitsubishi Heavy Industries Ltd., Kobe, Hyogo (Japan); Matsuoka, Takanori [Nuclear Development Corp., Tokai, Ibaraki (Japan); Urata, Sigeru; Mizuta, Hitoshi [Kansai Electric Power Co., Inc., Osaka (Japan)

    2000-03-01

    In this study, the cause of intergranular cracking in baffle former bolts(BFBs) was estimated from metallurgical and chemical viewpoints based upon the experimental data and information published by EdF. At first, five kinds of possibilities were estimated as the cause of intergranular cracking in BFBs. Five possibilities estimated were (1) mechanical cracking caused by high strain in irradiation hardened austenitic stainless steels, (2) O{sub 2} SCC due to residual oxygen in the bolt stagnant region, (3) caustic SCC due to dry and wet phenomenon, (4) low pH SCC due to oxygen concentration cell, and (5) PWSCC due to radiation induced segregation. In this study each possibility was evaluated by the calculation and some out of pile tests. And also, the cause of the intergranular cracking in BFBs was estimated by the data of the post-irradiation examinations and basic out of pile tests for Type 316CW and Type 347 stainless steels in the authors' previous study. From these evaluation, the intergranular cracking in BFBs seems to be caused by the PWSCC, but not caused by mechanical cracking O{sub 2} SCC, caustic SCC or low pH SCC. (author)

  1. Three-dimensional studies of intergranular carbides in austenitic stainless steel.

    Science.gov (United States)

    Ochi, Minoru; Kawano, Rika; Maeda, Takuya; Sato, Yukio; Teranishi, Ryo; Hara, Toru; Kikuchi, Masao; Kaneko, Kenji

    2017-04-01

    A large number of morphological studies of intergranular carbides in steels have always been carried out in two dimensions without considering their dispersion manners. In this article, focused ion beam serial-sectioning tomography was carried out to study the correlation among the grain boundary characteristics, the morphologies and the dispersions of intergranular carbides in 347 austenitic stainless steel. More than hundred intergranular carbides were characterized in three dimensions and finally classified into three different types, two types of carbides probably semi-coherent to one of the neighboring grains with plate-type morphology, and one type of carbides incoherent to both grains with rod-type morphology. In addition, the rod-type carbide was found as the largest number of carbides among three types. Since large numbers of defects, such as misfit dislocations, may be present at the grain boundaries, which can be ideal nucleation sites for intergranular rod-type carbide precipitation. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved.For permissions, please e-mail: journals.permissions@oup.com.

  2. Amorphous intergranular films in silicon nitride ceramics quenched from high temperatures

    International Nuclear Information System (INIS)

    Cinibulk, M.K.; Kleebe, H.; Schneider, G.A.; Ruehle, M.

    1993-01-01

    High-temperature microstructure of an MgO-hot-pressed Si 3 N 4 and a Yb 2 O 3 + Al 2 O 3 -sintered/annealed Si 3 N 4 were obtained by quenching thin specimens from temperatures between 1,350 and 1,550 C. Quenching materials from 1,350 C produced no observable exchanges in the secondary phases at triple-grain junctions or along grain boundaries. Although quenching from temperatures of ∼1,450 C also showed no significant changes in the general microstructure or morphology of the Si 3 N 4 grains, the amorphous intergranular film thickness increased substantially from an initial ∼1 nm in the slowly cooled material to 1.5--9 nm in the quenched materials. The variability of film thickness in a given material suggests a nonequilibrium state. Specimens quenched from 1,550 C revealed once again thin (1-nm) intergranular films at all high-angle grain boundaries, indicating an equilibrium condition. The changes observed in intergranular-film thickness by high-resolution electron microscopy can be related to the eutectic temperature of the system and to diffusional and viscous processes occurring in the amorphous intergranular film during the high-temperature anneal prior to quenching

  3. Effect of thickness and composition on the structure and ordering in La-doped intergranular films between Si{sub 3}N{sub 4} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Yun [Interfacial Molecular Science Laboratory, Department of Materials Science and Engineering, Rutgers University, 607 Taylor Rd., Piscataway, NJ 08855 (United States); Garofalini, Stephen H., E-mail: shg@rutgers.edu [Interfacial Molecular Science Laboratory, Department of Materials Science and Engineering, Rutgers University, 607 Taylor Rd., Piscataway, NJ 08855 (United States)

    2011-08-15

    Molecular dynamics simulations were used to determine the effect of the composition and thickness on the atomistic structure of La-Si-O-N intergranular films (IGFs) between prism and misaligned high-index silicon nitride crystals. Results showed that ordered La adsorption onto the prism-terminated surface is not affected by the orientation of the opposing crystal, although the extent of the ordering away from the interface is affected by IGF thickness. La adsorption at ordered sites 1 and 2 on the prism surface occurred for almost all of the compositions in both 1.8 and 0.6 nm thick IGFs and at sites farther from the prism interface in the thicker IGF, similar to adsorption in triple points. La adsorption on the prism surface occurred at sites precisely the same as seen in high-angle annular dark field scanning transmission electron microscopy studies. Saturation of available sites is affected by the thickness of the IGF, which governs the number of La ions (and N ions) in the IGF, with lower site filling in the thinner IGF. There are clear energy differences for La in the interior of the IGF vs. the interface based on composition and IGF thickness, with the thicker IGF showing greater variation in driving forces for segregation or La incorporation into the IGF. Fracture is affected by both composition and thickness and occurs in the glassy IGF and not in the ordered interfacial regions, consistent with experimentally observed intergranular fracture for La-doped silicon nitride. Segregation of La to the interface affects N distribution within the interior of the IGF, which affects strength.

  4. Intergranular stress corrosion cracking of ion irradiated 304L stainless steel in PWR environment

    International Nuclear Information System (INIS)

    Gupta, Jyoti

    2016-01-01

    IASCC is irradiation - assisted enhancement of intergranular stress corrosion cracking susceptibility of austenitic stainless steel. It is a complex degrading phenomenon which can have a significant influence on maintenance time and cost of PWRs' core internals and hence, is an issue of concern. Recent studies have proposed using ion irradiation (to be specific, proton irradiation) as an alternative of neutron irradiation to improve the current understanding of the mechanism. The objective of this study was to investigate the cracking susceptibility of irradiated SA 304L and factors contributing to cracking, using two different ion irradiations; iron and proton irradiations. Both resulted in generation of point defects in the microstructure and thereby causing hardening of the SA 304L. Material (unirradiated and iron irradiated) showed no susceptibility to intergranular cracking on subjection to SSRT with a strain rate of 5 * 10 -8 s -1 up to 4 % plastic strain in inert environment. But, irradiation (iron and proton) was found to increase intergranular cracking severity of material on subjection to SSRT in simulated PWR primary water environment at 340 C. Correlation between the cracking susceptibility and degree of localization was studied. Impact of iron irradiation on bulk oxidation of SA 304L was studied as well by conducting an oxidation test for 360 h in simulated PWR environment at 340 C. The findings of this study indicate that the intergranular cracking of 304L stainless steel in PWR environment can be studied using Fe irradiation despite its small penetration depth in material. Furthermore, it has been shown that the cracking was similar in both iron and proton irradiated samples despite different degrees of localization. Lastly, on establishing iron irradiation as a successful tool, it was used to study the impact of surface finish and strain paths on intergranular cracking susceptibility of the material. (author) [fr

  5. Effect of Silicon on Intergranular Corrosion Resistance of Ti-stabilized 11 wt% Cr Ferritic Stainless Steels

    International Nuclear Information System (INIS)

    Hyun, Youngmin; Kim, Heesan

    2013-01-01

    Ti-stabilized 11 wt% Cr ferritic stainless steels (FSSs) for automotive exhaust systems have been experienced intergranular corrosion (IC) in some heat-affected zone (HAZ). The effects of sensitizing heat-treatment and silicon on IC were studied. Time-Temperature-Sensitization (TTS) curves showed that sensitization to IC was observed at the steels heat-treated at the temperature lower than 650 .deg. C and that silicon improved IC resistance. The sensitization was explained by chromium depletion theory, where chromium is depleted by precipitation of chromium carbide during sensitizing heat-treatment. It was confirmed with the results from the analysis of precipitates as well as the thermodynamical prediction of stable phases. In addition, the role of silicon on IC was explained with the stabilization of grain boundary. In other words, silicon promoted the formation of the grain boundaries with low energy where precipitation was suppressed and consequently, the formation of Cr-depleted zone was retarded. The effect of silicon on the formation of grain boundaries with low energy was proved by the analysis of coincidence site lattice (CSL) grain boundary, which is a typical grain boundary with low energy

  6. Effect of Silicon on Intergranular Corrosion Resistance of Ti-stabilized 11 wt% Cr Ferritic Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Youngmin; Kim, Heesan [Hongik Univ., Sejong (Korea, Republic of)

    2013-06-15

    Ti-stabilized 11 wt% Cr ferritic stainless steels (FSSs) for automotive exhaust systems have been experienced intergranular corrosion (IC) in some heat-affected zone (HAZ). The effects of sensitizing heat-treatment and silicon on IC were studied. Time-Temperature-Sensitization (TTS) curves showed that sensitization to IC was observed at the steels heat-treated at the temperature lower than 650 .deg. C and that silicon improved IC resistance. The sensitization was explained by chromium depletion theory, where chromium is depleted by precipitation of chromium carbide during sensitizing heat-treatment. It was confirmed with the results from the analysis of precipitates as well as the thermodynamical prediction of stable phases. In addition, the role of silicon on IC was explained with the stabilization of grain boundary. In other words, silicon promoted the formation of the grain boundaries with low energy where precipitation was suppressed and consequently, the formation of Cr-depleted zone was retarded. The effect of silicon on the formation of grain boundaries with low energy was proved by the analysis of coincidence site lattice (CSL) grain boundary, which is a typical grain boundary with low energy.

  7. Intergranular stress corrosion in soldered joints of stainless steel 304.; Corrosion intergranular bajo esfuerzo en uniones soldadas de acero inoxidable 304

    Energy Technology Data Exchange (ETDEWEB)

    Zamora R, L [Instituto Nacional de Investigaciones Nucleares, Mexico City (Mexico)

    1994-12-31

    The intergranular stress cracking of welded joints of austenitic stainless steel, AISI 304, is a serious problem in BWR type reactors. It is associated with the simultaneous presence of three factors; stress, a critical media and sensibilization (DOS). EPR technique was used in order to verify the sensibilization degree in the base metal, and the zone affected by heat and welding material. The characterization of material was done. The objective of this work is the study of microstructure and the evaluation of EPR technique used for the determination of DOS in a welded plate of austenitic stainless steel AISI 304. (Author).

  8. The probability distribution of intergranular stress corrosion cracking life for sensitized 304 stainless steels in high temperature, high purity water

    International Nuclear Information System (INIS)

    Akashi, Masatsune; Kenjyo, Takao; Matsukura, Shinji; Kawamoto, Teruaki

    1984-01-01

    In order to discuss the probability distribution of intergranular stress corrsion carcking life for sensitized 304 stainless steels, a series of the creviced bent beem (CBB) and the uni-axial constant load tests were carried out in oxygenated high temperature, high purity water. The following concludions were resulted; (1) The initiation process of intergranular stress corrosion cracking has been assumed to be approximated by the Poisson stochastic process, based on the CBB test results. (2) The probability distribution of intergranular stress corrosion cracking life may consequently be approximated by the exponential probability distribution. (3) The experimental data could be fitted to the exponential probability distribution. (author)

  9. Microstructural sensitivity of 316H austenitic stainless steel: Residual stress relaxation and grain boundary fracture

    Energy Technology Data Exchange (ETDEWEB)

    Chen, B., E-mail: b.chen@bristol.ac.uk [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Flewitt, P.E.J. [Interface Analysis Centre, University of Bristol, 121 St Michael' s Hill, Bristol BS2 8BS (United Kingdom); H.H. Wills Physics Laboratory, School of Physics, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Smith, D.J. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom)

    2010-10-25

    Research highlights: {yields} Triaxial residual macro-stresses have been measured by neutron diffraction. {yields} Rates of stress relaxation are shown to be a function of the microstructure. {yields} Quantification of M{sub 23}C{sub 6} precipitation was undertaken by a novel approach. {yields} Intergranular M{sub 23}C{sub 6} precipitation promotes the potential to intergranular fracture. {yields} Phosphorous segregation further enhances the potential to intergranular fracture. - Abstract: The present work considers the role of thermo-mechanical history on the generation and relaxation of residual stresses, typical of those encountered in Type 316H austenitic stainless steel thick section weldments. A series of thermo-mechanical pre-treatments have been developed and applied to simulate the critical microstructures observed within the heat affected zone of the thick section parent material. The through thickness distributions of the residual macro-stresses in cylindrical specimens have been measured by neutron diffraction and then the rates of the relaxation are shown to be a function of microstructure. The susceptibility to intergranular brittle fracture at a temperature of -196 deg. C is shown to be a function of M{sub 23}C{sub 6} carbide precipitates and phosphorous segregation at the grain boundaries. Finally, the link of the present study to the understanding of the reheat cracking is briefly discussed.

  10. Influence of the grain boundary atomic structure on the intergranular precipitation

    International Nuclear Information System (INIS)

    Le Coze, J.

    1975-01-01

    The number of intergranular precipitates after long time annealing is calculated taking into account nucleation, growth and coarsening. With intermediate supersaturation, the great number of precipitates which is observed in some boundaries may have different causes: in low misorientation boundaries and (111) twin, the maxima come from semi-coherent nucleation with one grain; in the other boundaries, the maxima are connected with a great number of high energy atomic sites. Depending on supersaturation, some maxima may disappear whereas others are reinforced [fr

  11. Intergranular and inter-phased boundaries in the materials; Joints intergranulaires et interphases dans les materiaux

    Energy Technology Data Exchange (ETDEWEB)

    Aslanides, A. [Electricite de France, Dept. CIMA, 77 - Moret sur Loing (France); Backhaus-Ricoult, M. [Centre d' Etudes de Chimie metallurgique, 94 - Vitry-sur-Seine (France); Bayle-Guillemaud, P. [CEA Grenoble, Dept. de Recherche Fondamentale sur la Matiere Condensee, 38 (France)] [and others

    2000-07-01

    This document collects the abstracts of the talks presented during the colloquium J2IM on the intergranular and inter-phased boundaries in the materials. Around the themes of the interfaces behaviour and grain boundaries defects in materials, these days dealt with the microstructure behaviour in many domains such as the interfaces in batteries, the irradiation damages and the special case of the fuel-cladding interactions, the stressed interfaces, the alumina or silicon carbides substrates. (A.L.B.)

  12. Thresholds of time dependent intergranular crack growth in a nickel disc alloy Alloy 720Li

    Directory of Open Access Journals (Sweden)

    Li Hangyue

    2014-01-01

    Full Text Available At high temperatures in air, introducing a dwell period at the peak stress of fatigue cycles promotes time dependent intergranular crack growth which can increase crack growth rates by upto a few orders of magnitude from the rates of transgranular fatigue crack growth in superalloys. It is expected that time dependent intergranular crack growth in nickel-based superalloys may not occur below a critical mechanical driving force, ΔKth−IG, analogous to a fatigue threshold (ΔKth and a critical temperature, Tth. In this study, dwell fatigue crack growth tests have been carefully designed and conducted on Alloy 720Li to examine such thresholds. Unlike a fatigue threshold, the threshold stress intensity factor range for intergranular crack growth is observed to be highly sensitive to microstructure, dwell time and test procedure. The near threshold crack growth behaviour is made complex by the interactions between grain boundary oxidation embrittlement and crack tip stress relaxation. In general, lower ΔKth−IG values are associated with finer grain size and/or shorter dwell times. Often a load increasing procedure promotes stress relaxation and tends to lead to higher ΔKth−IG. When there is limited stress relaxation at the crack tip, similar ΔKth−IG values are measured with load increasing and load shedding procedures. They are generally higher than the fatigue threshold (ΔKth despite faster crack growth rates (da/dN in the stable crack growth regime. Time dependent intergranular crack growth cannot be activated below a temperature of 500 ∘C.

  13. Microstructural Evidences of Intergranular Pressure Solution during Frictional Sliding at Hydrothermal Conditions

    Science.gov (United States)

    Ma, X.; Yao, S.; He, C.

    2017-12-01

    In the framework of rate- and state-dependent friction, velocity weakening is the result of a healing effect at intergranular contacts that is stronger than the instantaneous rate effect. Intergranular pressure solution has been proposed to be a feasible mechanism for the frictional healing effect (He et al., 2013), but to date no substantial evidences have been reported in related microstructures. In this study we report our reanalyses on samples of plagioclase gouge deformed at hydrothermal conditions with effective normal stresses of 100 MPa, 200 MPa, and 300 MPa, pore pressures of 30 MPa and 100 MPa, and temperatures from 100oC to 600oC. With an Inlens image detector in a scanning electron microscope, our focus is to find the evidences of the pressure solution processes during frictional sliding. As it has been difficult to observe the signatures of pressure solution during frictional sliding at the solution sites due to the short contact time of frequently-switching contact pairs, now we focus on the results of precipitation instead, which is the final process of pressure solution. With high magnification, we find the following evidences of intergranular pressure solution: 1) crystal growth as a result of precipitation is ubiquitously observed in deformed samples at temperatures above 200oC; 2) very fine-grained precipitated particles with flaky morphologies typically appear in intensely sheared regions and between relatively large particles in moderately sheared regions; 3) the precipitated grains are concentrated periodically in zones orientated at 45-50 degrees to the fault strike. These observations indicate that intergranular pressure solution is the dominant process responsible for the frictional healing effect.

  14. Characterization of acoustic emission signals generated by water flow through intergranular stress corrosion cracks

    International Nuclear Information System (INIS)

    Claytor, T.N.; Kupperman, D.S.

    1985-05-01

    A program is under way at Argonne National Laboratory (ANL) to develop an independent capability to assess the effectiveness of current and proposed techniques for acoustic leak detection (ALD) in reactor coolant systems. The program will establish whether meaningful quantitative data on flow rates and leak location can be obtained from acoustic signatures of leaks due to intergranular stress corrosion cracks (TGSCCs) and fatigue cracks, and whether these can be distinguished from other types of leaks. 5 refs., 3 figs

  15. Intergranular phase of the Si3 N4 hot pressed with Mg O/Y2 O3

    International Nuclear Information System (INIS)

    Costa, Celio A.; Todd, Judith A.

    1997-01-01

    Monolithic and composite Si 3 N 4 hot-pressed with 3% Mgo or 6% Y 2 O 3 were analyzed with X-ray diffraction and transmission electron microscopy. The results showed materials to be composed of β-Si 3 N 4 grains and an intergranular phase which was partially crystalline and partially amorphous. For the materials sintered with Mg O, the identification of the intergranular phase was not conclusive. For the materials sintered with Y 2 O 3 . It was observed that the amount of intergranular crystalline phase decreased as whiskers were added to the material and the intergranular crystalline part had a crystallographic structure similar to yttrium-silicon-oxide-nitride family. (author)

  16. Effect of intergranular stress on yielding of 316H during room temperature cyclic loading

    International Nuclear Information System (INIS)

    Al Mamun, Abdullah; Moat, Richard; Bouchard, John; Kelleher, Joe

    2016-01-01

    Assessment of cyclic deformation is an integral part of nuclear power plant life assessment code, as many of the components in plant go through scheduled and unscheduled cyclic deformation owing to varying thermal and mechanical stresses. In polycrystalline material like 316H, a type of micro stress known as intergranular stress is generated due to elastic and plastic anisotropies during such cyclic loading. In tension-compression loading cycles, these stresses remain in the material as a residual stress upon unloading to zero stress from the tensile/compressive peak or intermediates stresses. The magnitude of these stresses vary depending on the point in the cycle from which it was unloaded from. When the material is re-loaded either in the same or reverse loading direction these residual stresses increase or decrease the effective stress acting in the material and as such the macroscopic yield stress of the material in subsequent cycle is changed significantly. The magnitude of intergranular stresses in many differently oriented grain families can be measured simultaneously using time of flight (ToF) neutron diffraction technique. In this paper, we have used this technique to experimentally study, how these intergranular stresses affect the yield (proof) stress of 316H at room temperature. (author)

  17. Evolution of interphase and intergranular stresses in Zr-2.5Nb during room temperature deformation

    International Nuclear Information System (INIS)

    Cai, S.; Daymond, M.R.; Holt, R.A.; Gharghouri, M.A.; Oliver, E.C.

    2009-01-01

    Both in situ tension and compression tests have been carried out on textured Zr-2.5Nb plate material at room temperature. Deformation along all the three principle plate directions has been studied and the evolution of interphase and intergranular strains along the loading and the principle Poisson's directions has been investigated by neutron diffraction. The evolution of interphase and intergranular strain was determined by the relative phase properties, crystal properties and texture distribution. The average phase behaviors are similar during tension and compression, where the β-phase in this material is stronger than the α-phase. The asymmetric yielding of the α-{0 0 0 2} grain family results in a relatively large intergranular strain in the loading direction during compression and different dependence of strength during tension and compression on texture. The combination of the thermal residual stress and the asymmetric CRSS in the axis gives the {0 0 0 2} grain family a higher strength in compression than in tension

  18. Hip Fracture

    Science.gov (United States)

    ... hip fractures in people of all ages. In older adults, a hip fracture is most often a result of a fall from a standing height. In people with very weak bones, a hip fracture can occur simply by standing on the leg and twisting. Risk factors The rate of hip fractures increases substantially with ...

  19. Microscale fracture mechanisms of a Cr3C2-NiCr HVOF coating

    International Nuclear Information System (INIS)

    Robertson, Andrew L.; White, Ken W.

    2017-01-01

    Thermal spray coatings, often composed of heterogeneous, multiphase microstructures, may, consequently, exhibit complex fracture behavior. For such coating structures, conventional mechanical evaluation methods fail to isolate the contribution of microstructural features to the overall fracture behavior. For this reason, this study employed focused ion beam machined (FIB) microcantilever beams and FIB sectioning methods to study the fracture mechanisms important at the scale of the heterogeneous Cr 3 C 2 -NiCr thermal spray coating. We found three fracture modes, namely, intergranular matrix fracture, matrix/carbide interfacial fracture, and carbide cleavage. By comparison, microindentation-induced cracks, the frequency of crack deflection around carbides is significantly more prevalent at this much larger crack dimension. This mechanistic variation provides some insight into the specific role and limitations of the microcantilever beam technique for fracture characterization of composite microstructures.

  20. The effect of multiaxial stress state on creep behavior and fracture mechanism of P92 steel

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yuan; Xu, Hong, E-mail: xuhong@ncepu.edu.cn; Ni, Yongzhong; Lan, Xiang; Li, Hongyuan

    2015-06-11

    The creep experiments on plain and double U-typed notched specimens were conducted on P92 steel at 650 °C. The notch strengthening effect was found in the notched specimens. Fracture appearance observed by scanning electron microscopy revealed that dimpled fracture for relatively blunt notched specimen, and dimpled fracture doubled with intergranular brittle fracture for relatively sharp notched specimen, which meant that fracture mechanism of P92 steel altered due to the presence of the notch. Meanwhile, based on Norton–Bailey and Kachanov–Robotnov constitutive models, a modified model was proposed. Finite element simulations were carried out to investigate the effect of multiaxial stress state on the creep behavior, fracture mechanism and damage evolvement of P92 steel. The simulation results agreed well with the fracture behaviors observed experimentally.

  1. On the Preservation of Intergranular Coesite in UHP Eclogite at Yangkou Bay, Sulu belt of eastern China

    Science.gov (United States)

    Wang, L.; Wang, S.; Brown, M.

    2016-12-01

    In contrast to coesite that occurs as inclusions in zircon and rock-forming minerals, intergranular coesite is preserved in UHP eclogite at Yangkou in the Sulu belt. The survival of intergranular coesite is intriguing because the eclogite experienced phengite growth and partial melting during exhumation. The coesite eclogite occurs as rootless isoclinal fold noses within quartz-rich schist which contains 10-20 vol% phengite, whereas phengite is absent from coesite eclogite in the fold noses. To evaluate the factors that control preservation of intergranular coesite, four samples representative of different stages along the retrograde P-T path were selected for study. For each sample we determined the number of intergranular coesite grains per cm2 and the OH content of garnet and omphacite. As the number of coesite grains decreases, the bulk rock OH content increases from transformation to quartz of intergranular coesite outside of the fold noses. The fluid is inferred to have been a supercritical fluid probably residual from prograde dehydration but also derived by dissolution of nominally anhydrous minerals. Post-metamorphic-peak deformation combined with fluid percolation along sheared fold limbs induced phengite growth during initial exhumation and then facilitated partial melting. In contrast, fold hinges in competent layers are unfavourable sites for fluid penetration. At Yangkou, the intergranular coesite is preserved in the fold noses where it was protected from both penetrative deformation and fluid ingress. Therefore, the fold noses maintained a relatively dry environment that allowed preservation of the intergranular coesite. Thus, deformation partitioning and strain localization impose local controls on fluid distribution and migration in UHP eclogite. This study informs our understanding of variations in fluid regime during exhumation of deeply subducted continental crust.

  2. The study of intergranular corrosion in aircraft aluminium alloys using X-ray tomography

    International Nuclear Information System (INIS)

    Knight, S.P.; Salagaras, M.; Trueman, A.R.

    2011-01-01

    Research highlights: → IGC is stochastic, where initiation is statistical and growth kinetics was somewhat predictable. → Dissolved oxygen concentration was more important than the concentration of salt in the droplet. → A limiting depth occurred for AA2024, whereas no limiting depth occurs for AA7050 after 168 h exposure. → A limiting depth may be controlled by the transport of dissolved oxygen down the corrosion fissure. → A limiting IGC depth is dependent on the overpotential of the SDZ (adjacent to the grain boundary). - Abstract: Atmospheric corrosion is one of the leading causes of structural damage to aircraft. Of particular importance is pitting and intergranular corrosion, which can develop into fatigue cracks, stress corrosion cracks, or exfoliation. Therefore it is of interest to the Australian Defence Force (ADF) to understand how corrosion ensues in susceptible aircraft aluminium alloys, such as AA2024-T351 and 7050-T7451. However, there are many difficulties in measuring the extent of intergranular corrosion, since it is predominantly hidden below the surface. Traditionally, cross-sectioning has been used to view and measure the depth of attack. In the present work, 2 mm diameter pin specimens were contaminated with a droplet of 3.5% NaCl and exposed to constant humidity that resulted in intergranular corrosion. X-ray computed tomography was then used to non-destructively assess the depth and volume of corrosion both as a function of time in 97% relative humidity, and as a function of relative humidity after 168 h exposure. Both corrosion depth and volume increased with time, but there was evidence for a limiting depth in AA2024. Depth and volume also increased with relative humidity of the environment, for which the time-of-wetness and oxygen concentration of the droplets were considered the important factors in driving the corrosion process.

  3. Oxidation studies of β-sialon ceramics containing amorphous and / or crystalline intergranular phases

    International Nuclear Information System (INIS)

    Persson, J.; Kall, P.O.; Jansson, K.; Nygren, M.

    1992-01-01

    β-sialon ceramics of equal overall compositions but containing amorphous, partly crystalline and almost completely crystalline intergranular phase(s) have been oxidized in oxygen at 1350 deg C for 20 hours. The obtained weight gain curves do not follow the parabolic rate law (ΔW/A 0 ) 2 = k p t + β. To the extent that crystallization occurs in the oxide scale during the oxidation experiment, the amorphous cross section area through which oxygen most easily diffuses will decrease with time. A brief description of this new rate law is given, and the obtained oxidation curves will be discussed within that framework. 4 refs., 2 tabs., 2 figs

  4. Signal Characteristics of Eddy Current Test for Intergranular Attack of Steam Generator Tubes

    International Nuclear Information System (INIS)

    Choi, Myung Sik; Lee, Deok Hyun; Han, Jung Ho; Hur, Do Haeng; Cho, Se Gon; Yim, Chang Jae

    2002-01-01

    Because intergranular attack (IGA), one of the localized corrosion forms occurring on steam generator tubes, can not be fabricated by an electric discharge machining method, there are few data for the eddy current test (ECT) characteristics of IGA. In this paper, the characteristics of eddy current signals are evaluated using nonexpanded tubes with IGA defects formed in 0.1 M sodium tetrathionate solution at 40 .deg. C. The detectability and sizing accuracy of IGA were discussed in terms of the coil type and frequency of the ECT probes

  5. In-situ Investigation of the Fracture Behaviors of 2195-T8 Aluminum-Lithium alloy

    Directory of Open Access Journals (Sweden)

    Wang Liang

    2016-01-01

    Full Text Available In this paper, the tensile crack initiation and propagation behavior of 2195-T8 Aluminum-Lithium alloy was studied by in situ scanning electron microscope observation at room temperature. It was found that cracks initiated at second phases which propagated along the grain boundaries only as T1 phases could retard crack growth inside grains. With further increase of strain, within the grain a large number of slip bands were produced, resulting in the deflection of the grains, which leaded to transgranular fracture at last. SEM examination show both intergranular and transgranular fracture surface morphology indicating that the 2195-T8 alloy revealed a mix mechanism for the fracture.

  6. Techniques for intergranular crack formation and assessment in alloy 600 base and alloy 182 weld metals

    Directory of Open Access Journals (Sweden)

    Tae Hyun Lee

    2015-02-01

    Conclusion: A comparison with a destructive metallographic examination showed that the characteristics, orientations, and sizes of the intergranular cracks produced in this study are highly reproducible.

  7. Meso-microstructural computational simulation of the hydrogen permeation test to calculate intergranular, grain boundary and effective diffusivities

    Energy Technology Data Exchange (ETDEWEB)

    Jothi, S., E-mail: s.jothi@swansea.ac.uk [College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Winzer, N. [Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg (Germany); Croft, T.N.; Brown, S.G.R. [College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom)

    2015-10-05

    Highlights: • Characterized polycrystalline nickel microstructure using EBSD analysis. • Development meso-microstructural model based on real microstructure. • Calculated effective diffusivity using experimental electrochemical permeation test. • Calculated intergranular diffusivity of hydrogen using computational FE simulation. • Validated the calculated computation simulation results with experimental results. - Abstract: Hydrogen induced intergranular embrittlement has been identified as a cause of failure of aerospace components such as combustion chambers made from electrodeposited polycrystalline nickel. Accurate computational analysis of this process requires knowledge of the differential in hydrogen transport in the intergranular and intragranular regions. The effective diffusion coefficient of hydrogen may be measured experimentally, though experimental measurement of the intergranular grain boundary diffusion coefficient of hydrogen requires significant effort. Therefore an approach to calculate the intergranular GB hydrogen diffusivity using finite element analysis was developed. The effective diffusivity of hydrogen in polycrystalline nickel was measured using electrochemical permeation tests. Data from electron backscatter diffraction measurements were used to construct microstructural representative volume elements including details of grain size and shape and volume fraction of grains and grain boundaries. A Python optimization code has been developed for the ABAQUS environment to calculate the unknown grain boundary diffusivity.

  8. The intergranular corrosion behavior of 6000-series alloys with different Mg/Si and Cu content

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Yun; Liu, Qing, E-mail: qingliu@cqu.edu.cn; Jia, Zhihong, E-mail: zhihongjia@cqu.edu.cn; Xing, Yuan; Ding, Lipeng; Wang, Xueli

    2017-05-31

    Highlights: • High Cu alloy with high Mg/Si ratio has the best comprehensive property. • Addition of excess Mg could improve the intergranular corrosion resistance. • Si containing particles on the grain boundaries of Si-rich alloys promote IGC. • IGC susceptibility depends primarily on Cu content and secondarily on Mg/Si ratio. - Abstract: 6000-series aluminium alloys with high Cu or excess Si addition were susceptible to intergranular corrosion (IGC). In order to obtain good IGC resistance, four alloys with low/high Cu and various Mg/Si ratios were designed. The corrosion behaviour of four alloys was investigated by accelerated corrosion test, electrochemical test and electron microscopies. It was revealed that IGC susceptibility of alloys was the result of microgalvanic coupling between the noble grain boundary precipitates and the adjacent precipitates free zone (PFZ), which was closely related to a combination of Cu content and the Mg/Si ratio. Excess Mg could improve the IGC resistance of alloys by forming discontinuous precipitates on the grain boundaries. The designed alloy with high Cu and excess Mg has the same corrosion level as the commercial alloy with low Cu and excess Si, which provides possibility for developing new alloy.

  9. Fission-induced recrystallization effect on intergranular bubble-driven swelling in U-Mo fuel

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Linyun; Mei, Zhi-Gang; Yacout, Abdellatif M.

    2017-10-01

    We have developed a mesoscale phase-field model for studying the effect of recrystallization on the gas-bubble-driven swelling in irradiated U-Mo alloy fuel. The model can simulate the microstructural evolution of the intergranular gas bubbles on the grain boundaries as well as the recrystallization process. Our simulation results show that the intergranular gas-bubble-induced fuel swelling exhibits two stages: slow swelling kinetics before recrystallization and rapid swelling kinetics with recrystallization. We observe that the recrystallization can significantly expedite the formation and growth of gas bubbles at high fission densities. The reason is that the recrystallization process increases the nucleation probability of gas bubbles and reduces the diffusion time of fission gases from grain interior to grain boundaries by increasing the grain boundary area and decreasing the diffusion distance. The simulated gas bubble shape, size distribution, and density on the grain boundaries are consistent with experimental measurements. We investigate the effect of the recrystallization on the gas-bubble-driven fuel swelling in UMo through varying the initial grain size and grain aspect ratio. We conclude that the initial microstructure of fuel, such as grain size and grain aspect ratio, can be used to effectively control the recrystallization and therefore reduce the swelling in U-Mo fuel.

  10. Automated identification of intergranular corrosion in X-ray CT images

    International Nuclear Information System (INIS)

    Howell, Patricia A.; Winfree, William P.

    2003-01-01

    Characterization of a material or structure by computed tomography results in the acquisition of large quantities of data that need to be tediously examined to determine the location and size of damage. Since the computed tomography images are digital, there is significant potential for reducing the human effort evolved in this process by digital processing of this data to enhance the signatures of flaws and perform automated identification of suspected flaws. Techniques are presented that enhance the contrast between corroded and uncorroded regions to simplify the analysis and improve quality of flaw identification. Algorithms developed in part for computer vision, such as anisotropic diffusion and edge detection techniques, are applied to the data. Anisotropic diffusion techniques are shown to significantly reduce image noise while maintaining the contrast between intergranular corrosion and uncorroded regions and preserving the important features of the flaw. Edge detection techniques are shown to enable a rapid location of regions requiring further analysis. In regions identified by the edge detection technique, neural network techniques are applied to automate defect detection of the intergranular corrosion

  11. The distribution of intergranular gaps along α tracks recorded in ionographic emulsions

    International Nuclear Information System (INIS)

    Wittendorp-Rechenmann, E.; Senger, B.; Koziel-Vigneron, V.; Rechenmann, R.V.

    1990-01-01

    Detailed microscopic analyses performed at high statistics (size: 1100) on 8.776 MeV α tracks materialised in nuclear emulsion demonstrated a distribution of intergranular gaps along the primary ion's path that was not only non-random but also fluctuated significantly with the energy of the projectile. The highest and lowest gap frequencies measured correspond to the energy region of 0.7 - 1.5 MeV and 7 MeV, respectively. The gap length distributions followed an exponential law, a known characteristic of the intergranular gaps distributed along the tracks of high energy charged particles. A tentative interpretation of these observations has been undertaken in terms of spatial distributions of δ rays around the incoming ion's path, by applying the Double-Differential Cross-Section Mixed Treatment to the geometrical configuration of the AgBr microcrystals embedded in the gelatin matrix. At this preliminary stage of our modelling, the main experimental data could already be reproduced satisfactorily. (author)

  12. Order in nanometer thick intergranular films at Au-sapphire interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Baram, Mor [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Garofalini, Stephen H. [Department of Materials Science and Engineering, Rutgers University, Piscataway, NJ 08854-8065 (United States); Kaplan, Wayne D., E-mail: kaplan@tx.technion.ac.il [Department of Materials Engineering, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2011-08-15

    Highlights: {yields} Au particles were equilibrated on (0 0 0 1) sapphire in the presence of anorthite. {yields} 1.2 nm thick equilibrium films (complexions) were formed at the Au-sapphire interfaces. {yields} Quantitative HRTEM was used to study the atomistic structure of the films. {yields} Structural order was observed in the 1.2 nm thick films adjacent to the sapphire crystal. {yields} This demonstrates that ordering is an intrinsic part of equilibrium intergranular films. - Abstract: In recent years extensive studies on interfaces have shown that {approx}1 nm thick intergranular films (IGF) exist at interfaces in different material systems, and that IGF can significantly affect the materials' properties. However, there is great deal of uncertainty whether such films are amorphous or partially ordered. In this study specimens were prepared from Au particles that were equilibrated on sapphire substrates in the presence of anorthite glass, leading to the formation of 1.2 nm thick IGF at the Au-sapphire interfaces. Site-specific cross-section samples were characterized using quantitative high resolution transmission electron microscopy to study the atomistic structure of the films. Order was observed in the 1.2 nm thick films adjacent to the sapphire crystal in the form of 'Ca cages', experimentally demonstrating that ordering is an intrinsic part of IGF, as predicted from molecular dynamics and diffuse interface theory.

  13. Suppressed Belief

    Directory of Open Access Journals (Sweden)

    Komarine Romdenh-Romluc

    2009-12-01

    Full Text Available Moran’s revised conception of conscious belief requires us to reconceptualise suppressed belief. The work of Merleau-Ponty offers a way to do this. His account of motor-skills allows us to understand suppressed beliefs as pre-reflective ways of dealing with the world.

  14. Rib Fractures

    Science.gov (United States)

    ... Video) Achilles Tendon Tear Additional Content Medical News Rib Fractures By Thomas G. Weiser, MD, MPH, Associate Professor, ... Tamponade Hemothorax Injury to the Aorta Pulmonary Contusion Rib Fractures Tension Pneumothorax Traumatic Pneumothorax (See also Introduction to ...

  15. Root fractures

    DEFF Research Database (Denmark)

    Andreasen, Jens Ove; Christensen, Søren Steno Ahrensburg; Tsilingaridis, Georgios

    2012-01-01

    The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed....

  16. Stress Fractures

    Science.gov (United States)

    Stress fractures Overview Stress fractures are tiny cracks in a bone. They're caused by repetitive force, often from overuse — such as repeatedly jumping up and down or running long distances. Stress fractures can also arise from normal use of ...

  17. The effect of sintering temperature on the intergranular properties and weak link behavior of Bi2223 superconductors

    Directory of Open Access Journals (Sweden)

    P. Kameli

    2006-03-01

    Full Text Available  A systematic study of the intergranular properties of (Bi,Pb2 Sr2 Ca2 Cu3 Oy (Bi2223 polycrystalline samples has been done using the electrical resistivity and AC susceptibility techniques. In this study, we have prepared a series of Bi2223 samples with different sintering temperatures. The XRD results show that by increasing the sintering temperature up to 865° c , the Bi2212 phase fraction decreases. It was found that the Bi2212 phase on the grain boundaries is likely to play the role of the weak links and consequently reduces the intergranular critical current densities.

  18. The influence of He on the high temperature fracture of an austenitic stainless steel

    International Nuclear Information System (INIS)

    Saguees, A.A.

    1976-01-01

    The Ti-stabilised DIN 1.4970 austenitic stainless steel is an important candidate for high temperature - high neutron fluence applications which will create appreciable amounts of He within the matrix. In order to determine the mechanical effects associated with the presence of He alone a set of tensile specimens was cyclotron implanted to uniform He concentrations in the 10 -6 to 10 -4 at. range and later creep tested at 700 0 C and 800 0 C. The elongation to fracture values of the implanted specimens were reduced with respect to those of unimplanted controls. Scanning Electron Microscope (SEM) examination revealed that fracture starts as intergranular and subsequently propagates in a transgranular fashion, the intergranular part being much more extended in the implanted material. Transmission Electron Microscope (TEM) examination revealed He segregation at the grain boundary precipitates. A mechanism of He embrittlement is discussed in terms of the present results

  19. High temperature tensile properties and fracture characteristics of bimodal 12Cr-ODS steel

    International Nuclear Information System (INIS)

    Chauhan, Ankur; Litvinov, Dimitri; Aktaa, Jarir

    2016-01-01

    This article describes the tensile properties and fracture characteristics of a 12Cr oxide dispersion strengthened (ODS) ferritic steel with unique elongated bimodal grain size distribution. The tensile tests were carried out at four different temperatures, ranging from room temperature to 700 °C, at a nominal strain rate of 10"−"3 s"−"1. At room temperature the material exhibits a high tensile strength of 1294 MPa and high yield strength of 1200 MPa. At 700 °C, the material still exhibits relatively high tensile strength of 300 MPa. The total elongation-to-failure exceeds 18% over the whole temperature range and has a maximum value of 29% at 600 °C. This superior ductility is attributed to the material's bimodal grain size distribution. In comparison to other commercial, as well as experimental, ODS steels, the material shows an excellent compromise between strength and ductility. The fracture surface studies reveal a change in fracture behavior from a mixed mode fracture at room temperature to fully ductile fracture at 600 °C. At 700 °C, the fracture path changes from intragranular to intergranular fracture, which is associated with a reduced ductility. - Highlights: • The steel has a unique elongated bimodal grain size distribution. • The steel shows an excellent compromise between strength and ductility. • Superior ductility in comparison to other commercial and experimental ODS steels. • Fracture behavior changes from mixed mode fracture at room temperature to fully ductile fracture at 600 °C. • Fracture path changes from intragranular to intergranular fracture at 700 °C.

  20. Mitigation of intergranular stress corrosion cracking in RBMK reactors. Final report of the programme's steering committee

    International Nuclear Information System (INIS)

    2002-09-01

    In 2000 the IAEA initiated an Extrabudgetary Programme on Mitigation of Intergranular Stress Corrosion Cracking in RBMK Reactors to assist countries operating RBMK reactors in addressing the issue in austenitic stainless steel 300 mm diameter piping. Intergranular stress corrosion cracking of austenitic stainless steel piping in BWRs has been a major safety concern since the early seventies. Similar degradation was found in RBMK reactor piping in 1997. Early in 1998 the IAEA responded to requests for assistance from RBMK operating countries on this issue through activities organized in the framework of Technical Co-operation Department regional projects and the Extrabudgetary Programme on the Safety of WWER and RBMK Nuclear Power Plants. Results of these activities were a basis for the formulation of the objective and scope of the Extrabudgetary Programme on Mitigation of Intergranular Stress Corrosion Cracking in RBMK reactors ('the Programme'). The scope of the Programme included in-service inspection, assessment, repair and mitigation, and water chemistry and decontamination. The Programme was pursued by means of exchange of experience, formulation of guidance, transfer of technology, and training, which will assist the RBMK operators to address related safety concerns. The Programme implementation relied on voluntary extrabudgetary financial contributions from Japan, Spain, the United Kingdom and the USA, and on in kind contributions from Finland, Germany and Sweden. The Programme was implemented in close co-ordination with ongoing national and bilateral activities and major inputs to the Programme were provided through the activities of the Swedish International Project Nuclear Safety and of the US DOE International Nuclear Safety Program. The RBMK nuclear power plants in Lithuania, Russian Federation and Ukraine hosted most of the Programme activities. Support of these Member States involved in the Programme was instrumental for its successful completion in

  1. Microscale fracture mechanisms of a Cr{sub 3}C{sub 2}-NiCr HVOF coating

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Andrew L., E-mail: Andrew.robertson99987@gmail.com; White, Ken W.

    2017-03-14

    Thermal spray coatings, often composed of heterogeneous, multiphase microstructures, may, consequently, exhibit complex fracture behavior. For such coating structures, conventional mechanical evaluation methods fail to isolate the contribution of microstructural features to the overall fracture behavior. For this reason, this study employed focused ion beam machined (FIB) microcantilever beams and FIB sectioning methods to study the fracture mechanisms important at the scale of the heterogeneous Cr{sub 3}C{sub 2}-NiCr thermal spray coating. We found three fracture modes, namely, intergranular matrix fracture, matrix/carbide interfacial fracture, and carbide cleavage. By comparison, microindentation-induced cracks, the frequency of crack deflection around carbides is significantly more prevalent at this much larger crack dimension. This mechanistic variation provides some insight into the specific role and limitations of the microcantilever beam technique for fracture characterization of composite microstructures.

  2. Ultra high vacuum fracture and transfer device for AES analysis of irradiated austenitic stainless steel

    International Nuclear Information System (INIS)

    Urie, M.W.; Panayotou, N.F.; Robinson, J.E.

    1980-01-01

    An ultrahigh vacuum fracture and transfer device for analysis of irradiated and non-irradiated SS 316 fuel cladding is described. Mechanical property tests used to study the behavior of cladding during reactor transient over-power conditions are reported. The stress vs temperature curves show minimal differences between unirradiated cladding and unfueled cladding. The fueled cladding fails at a lower temperature. All fueled specimens failed in an intergranular mode

  3. Theoretical study of the elasticity, mechanical behavior, electronic structure, interatomic bonding, and dielectric function of an intergranular glassy film model in prismatic β-Si3N4

    International Nuclear Information System (INIS)

    Ching, W. Y.; Rulis, Paul; Aryal, Sitaram; Ouyang, Lizhi; Misra, Anil

    2010-01-01

    Microstructures such as intergranular glassy films (IGFs) are ubiquitous in many structural ceramics. They control many of the important physical properties of polycrystalline ceramics and can be influenced during processing to modify the performance of devices that contain them. In recent years, there has been intense research, both experimentally and computationally, on the structure and properties of IGFs. Unlike grain boundaries or dislocations with well-defined crystalline planes, the atomic scale structure of IGFs, their fundamental electronic interactions, and their bonding characteristics are far more complicated and not well known. In this paper, we present the results of theoretical simulations using ab initio methods on an IGF model in β-Si 3 N 4 with prismatic crystalline planes. The 907-atom model has a dimension of 14.533 A x 15.225 A x 47.420 A . The IGF layer is perpendicular to the z axis, 16.4 A wide, and contains 72 Si, 32 N, and 124 O atoms. Based on this model, the mechanical and elastic properties, the electronic structure, the interatomic bonding, the localization of defective states, the distribution of electrostatic potential, and the optical dielectric function are evaluated and compared with crystalline β-Si 3 N 4 . We have also performed a theoretical tensile experiment on this model by incrementally extending the structure in the direction perpendicular to the IGF plane until the model fully separated. It is shown that fracture occurs at a strain of 9.42% with a maximum stress of 13.9 GPa. The fractured segments show plastic behavior and the formation of surfacial films on the β-Si 3 N 4 . These results are very different from those of a previously studied basal plane model [J. Chen et al., Phys. Rev. Lett. 95, 256103 (2005)] and add insights to the structure and behavior of IGFs in polycrystalline ceramics. The implications of these results and the need for further investigations are discussed.

  4. Cleavage and creep fracture of rock salt

    International Nuclear Information System (INIS)

    Chan, K.S.; Munson, D.E.; Bodner, S.R.

    1996-01-01

    The dominant failure mechanism in rock salt at ambient temperature is either cleavage or creep fracture. Since the transition of creep fracture to cleavage in a compressive stress field is not well understood, failure of rock salt by cleavage and creep fracture is analyzed in this paper to elucidate the effect of stress state on the competition between these two fracture mechanisms. For cleavage fracture, a shear crack is assumed to cause the formation and growth of a symmetric pair of wing cracks in a predominantly compressive stress field. The conditions for wing-crack instability are derived and presented as the cleavage fracture boundary in the fracture mechanism map. Using an existing creep fracture model, stress conditions for the onset of creep fracture and isochronous failure curves of specified times-to-rupture are calculated and incorporated into the fracture mechanism map. The regimes of dominance by cleavage and creep fracture are established and compared with experimental data. The result indicates that unstable propagation of cleavage cracks occurs only in the presence of tensile stress. The onset of creep fracture is promoted by a tensile stress, but can be totally suppressed by a high confining pressure. Transition of creep fracture to cleavage occurs when critical conditions of stress difference and tensile stress for crack instability are exceeded

  5. Acetabular Fracture

    Directory of Open Access Journals (Sweden)

    Chad Correa

    2017-09-01

    Full Text Available History of present illness: A 77-year-old female presented to her primary care physician (PCP with right hip pain after a mechanical fall. She did not lose consciousness or have any other traumatic injuries. She was unable to ambulate post-fall, so X-rays were ordered by her PCP. Her X-rays were concerning for a right acetabular fracture (see purple arrows, so the patient was referred to the emergency department where a computed tomography (CT scan was ordered. Significant findings: The non-contrast CT images show a minimally displaced comminuted fracture of the right acetabulum involving the acetabular roof, medial and anterior walls (red arrows, with associated obturator muscle hematoma (blue oval. Discussion: Acetabular fractures are quite rare. There are 37 pelvic fractures per 100,000 people in the United States annually, and only 10% of these involve the acetabulum. They occur more frequently in the elderly totaling an estimated 4,000 per year. High-energy trauma is the primary cause of acetabular fractures in younger individuals and these fractures are commonly associated with other fractures and pelvic ring disruptions. Fractures secondary to moderate or minimal trauma are increasingly of concern in patients of advanced age.1 Classification of acetabular fractures can be challenging. However, the approach can be simplified by remembering the three basic types of acetabular fractures (column, transverse, and wall and their corresponding radiologic views. First, column fractures should be evaluated with coronally oriented CT images. This type of fracture demonstrates a coronal fracture line running caudad to craniad, essentially breaking the acetabulum into two halves: a front half and a back half. Secondly, transverse fractures should be evaluated by sagittally oriented CT images. By definition, a transverse fracture separates the acetabulum into superior and inferior halves with the fracture line extending from anterior to posterior

  6. Influence of Si content on the intergranular corrosion of SUS 309L stainless steels

    International Nuclear Information System (INIS)

    Lin, D.-Y.; Chang, T.-C.

    2003-01-01

    The effect of Si content on the intergranular corrosion resistance of SUS 309L stainless steels was investigated by 10 wt.% oxalic acid test, 65 wt.% boiling nitric acid test, double loop electrochemical potential reactivation (DLEPR) method, optical microscope (OM) and scanning electronic microscope (SEM). A maximum corrosion rate, weight loss of 2.80 g m -1 h, was obtained when SUS 309L stainless steel containing 0.73 wt.% Si was subjected to heat treatment at 800 deg. C for 1 h. It shows that the Cr depletion zone formed due to σ phase precipitation. The same result is obtained in DLEPR test and the ditch microstructure after oxalic test was found in samples that showed the minimum corrosion rate

  7. Mitigating Intergranular Stress Corrosion Cracking in Age-Hardenable Al-Zn-Mg-Cu Alloys

    Science.gov (United States)

    Ajay Krishnan, M.; Raja, V. S.; Shukla, Shweta; Vaidya, S. M.

    2018-06-01

    This article reports an attempt to develop high-strength aluminum alloys of 7xxx series resistant to intergranular stress corrosion cracking (SCC). A novel aging technique reported in this work exhibited improved strength levels (as high as 100 MPa to that of conventional overaged temper for AA 7050) with significant resistance to SCC measured even at a low strain rate (10-7 s-1) in 3.5 wt pct NaCl. The novel aging heat treatment produced a microstructure that is finer and dense enough in the matrix to impart strength, whereas it is enriched with Cu on the grain boundaries to impart SCC resistance. A detailed explanation for the enhanced strength and SCC resistance is discussed.

  8. Mitigating Intergranular Stress Corrosion Cracking in Age-Hardenable Al-Zn-Mg-Cu Alloys

    Science.gov (United States)

    Ajay Krishnan, M.; Raja, V. S.; Shukla, Shweta; Vaidya, S. M.

    2018-04-01

    This article reports an attempt to develop high-strength aluminum alloys of 7xxx series resistant to intergranular stress corrosion cracking (SCC). A novel aging technique reported in this work exhibited improved strength levels (as high as 100 MPa to that of conventional overaged temper for AA 7050) with significant resistance to SCC measured even at a low strain rate (10-7 s-1) in 3.5 wt pct NaCl. The novel aging heat treatment produced a microstructure that is finer and dense enough in the matrix to impart strength, whereas it is enriched with Cu on the grain boundaries to impart SCC resistance. A detailed explanation for the enhanced strength and SCC resistance is discussed.

  9. Development of intergranular thermal residual stresses in beryllium during cooling from processing temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Brown, D.W. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)], E-mail: dbrown@lanl.gov; Sisneros, T.A.; Clausen, B.; Abeln, S.; Bourke, M.A.M.; Smith, B.G.; Steinzig, M.L.; Tome, C.N.; Vogel, S.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2009-02-15

    The intergranular thermal residual stresses in texture-free solid polycrystalline beryllium were determined by comparison of crystallographic lattice parameters in solid and powder samples measured by neutron diffraction during cooling from 800 deg. C. The internal stresses are not significantly different from zero >575 deg. C and increase nearly linearly <525 deg. C. At room temperature, the c axis of an average grain is under {approx}200 MPa of compressive internal stress, and the a axis is under 100 MPa of tensile stress. For comparison, the stresses have also been calculated using an Eshelby-type polycrystalline model. The measurements and calculations agree very well when temperature dependence of elastic constants is accounted for, and no plastic relaxation is allowed in the model.

  10. Analysis of intergranular fission-gas bubble-size distributions in irradiated uranium-molybdenum alloy fuel

    Energy Technology Data Exchange (ETDEWEB)

    Rest, J. [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)], E-mail: jrest@anl.gov; Hofman, G.L.; Kim, Yeon Soo [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States)

    2009-04-15

    An analytical model for the nucleation and growth of intra and intergranular fission-gas bubbles is used to characterize fission-gas bubble development in low-enriched U-Mo alloy fuel irradiated in the advanced test reactor in Idaho as part of the Reduced Enrichment for Research and Test Reactor (RERTR) program. Fuel burnup was limited to less than {approx}7.8 at.% U in order to capture the fuel-swelling stage prior to irradiation-induced recrystallization. The model couples the calculation of the time evolution of the average intergranular bubble radius and number density to the calculation of the intergranular bubble-size distribution based on differential growth rate and sputtering coalescence processes. Recent results on TEM analysis of intragranular bubbles in U-Mo were used to set the irradiation-induced diffusivity and re-solution rate in the bubble-swelling model. Using these values, good agreement was obtained for intergranular bubble distribution compared against measured post-irradiation examination (PIE) data using grain-boundary diffusion enhancement factors of 15-125, depending on the Mo concentration. This range of enhancement factors is consistent with values obtained in the literature.

  11. Analysis of intergranular fission-gas bubble-size distributions in irradiated uranium-molybdenum alloy fuel

    Science.gov (United States)

    Rest, J.; Hofman, G. L.; Kim, Yeon Soo

    2009-04-01

    An analytical model for the nucleation and growth of intra and intergranular fission-gas bubbles is used to characterize fission-gas bubble development in low-enriched U-Mo alloy fuel irradiated in the advanced test reactor in Idaho as part of the Reduced Enrichment for Research and Test Reactor (RERTR) program. Fuel burnup was limited to less than ˜7.8 at.% U in order to capture the fuel-swelling stage prior to irradiation-induced recrystallization. The model couples the calculation of the time evolution of the average intergranular bubble radius and number density to the calculation of the intergranular bubble-size distribution based on differential growth rate and sputtering coalescence processes. Recent results on TEM analysis of intragranular bubbles in U-Mo were used to set the irradiation-induced diffusivity and re-solution rate in the bubble-swelling model. Using these values, good agreement was obtained for intergranular bubble distribution compared against measured post-irradiation examination (PIE) data using grain-boundary diffusion enhancement factors of 15-125, depending on the Mo concentration. This range of enhancement factors is consistent with values obtained in the literature.

  12. Evaluation of intergranular corrosion techniques to determine phosphorus segregation in NiCrMoV rotor steel

    International Nuclear Information System (INIS)

    Bruemmer, S.M.; Thomas, M.T.; Arey, B.W.

    1985-01-01

    Several chemical and electrochemical etching techniques have been evaluated for the indirect measurement of grain boundary phosphorus segregation. A picric acid based solution was found to promote intergranular attack proportional to the grain boundary phosphorus composition measured by Auger Electron Spectroscopy. Preliminary results indicate this solution may enable the nondestructive evaluation of a rotor steel's susceptibility to temper embrittlement and IGSCC

  13. Pattern recognition model to estimate intergranular stress corrosion cracking (IGSCC) at crevices and pit sites of 304 SS in BWR environments

    Energy Technology Data Exchange (ETDEWEB)

    Urquidi-Macdonald, Mirna [Penn State University, 212 Earth-Engineering Science Building, University Park, PA 16801 (United States)

    2004-07-01

    Many publications have shown that crack growth rates (CGR) due to intergranular stress corrosion cracking (IGSCC) of metals is dependent on many parameters related to the manufacturing process of the steel and the environment to which the steel is exposed. Those parameters include, but are not restricted to, the concentration of chloride, fluoride, nitrates, and sulfates, pH, fluid velocity, electrochemical potential (ECP), electrolyte conductivity, stress and sensitization applied to the steel during its production and use. It is not well established how combinations of each of these parameters impact the CGR. Many different models and beliefs have been published, resulting in predictions that sometimes disagree with experimental observations. To some extent, the models are the closest to the nature of IGSCC, however, there is not a model that fully describes the entire range of observations, due to the difficulty of the problem. Among the models, the Fracture Environment Model, developed by Macdonald et al., is the most physico-chemical model, accounting for experimental observations in a wide range of environments or ECPs. In this work, we collected experimental data on BWR environments and designed a data mining pattern recognition model to learn from that data. The model was used to generate CGR estimations as a function of ECP on a BWR environment. The results of the predictive model were compared to the Fracture Environment Model predictions. The results from those two models are very close to the experimental observations of the area corresponding to creep and IGSCC controlled by diffusion. At more negative ECPs than the potential corresponding to creep, the pattern recognition predicts an increase of CGR with decreasing ECP, while the Fracture Environment Model predicts the opposite. The results of this comparison confirm that the pattern recognition model covers 3 phenomena: hydrogen embrittlement at very negative ECP, creep at intermediate ECP, and IGSCC

  14. Pattern recognition model to estimate intergranular stress corrosion cracking (IGSCC) at crevices and pit sites of 304 SS in BWR environments

    International Nuclear Information System (INIS)

    Urquidi-Macdonald, Mirna

    2004-01-01

    Many publications have shown that crack growth rates (CGR) due to intergranular stress corrosion cracking (IGSCC) of metals is dependent on many parameters related to the manufacturing process of the steel and the environment to which the steel is exposed. Those parameters include, but are not restricted to, the concentration of chloride, fluoride, nitrates, and sulfates, pH, fluid velocity, electrochemical potential (ECP), electrolyte conductivity, stress and sensitization applied to the steel during its production and use. It is not well established how combinations of each of these parameters impact the CGR. Many different models and beliefs have been published, resulting in predictions that sometimes disagree with experimental observations. To some extent, the models are the closest to the nature of IGSCC, however, there is not a model that fully describes the entire range of observations, due to the difficulty of the problem. Among the models, the Fracture Environment Model, developed by Macdonald et al., is the most physico-chemical model, accounting for experimental observations in a wide range of environments or ECPs. In this work, we collected experimental data on BWR environments and designed a data mining pattern recognition model to learn from that data. The model was used to generate CGR estimations as a function of ECP on a BWR environment. The results of the predictive model were compared to the Fracture Environment Model predictions. The results from those two models are very close to the experimental observations of the area corresponding to creep and IGSCC controlled by diffusion. At more negative ECPs than the potential corresponding to creep, the pattern recognition predicts an increase of CGR with decreasing ECP, while the Fracture Environment Model predicts the opposite. The results of this comparison confirm that the pattern recognition model covers 3 phenomena: hydrogen embrittlement at very negative ECP, creep at intermediate ECP, and IGSCC

  15. Hydrogen pressure dependence of the fracture mode transition in nickel

    International Nuclear Information System (INIS)

    Jones, R.H.; Baer, D.R.; Bruemmer, S.M.; Thomas, M.T.

    1983-01-01

    A relationship between fracture mode, grain boundary composition, and hydrogen pressure has been determined for nickel straining electrode samples tested at cathodic potentials. This relationship can be expressed as C /SUB s/ α P /SUP -n/ /SUB H2/ where C /SUB s/ is the critical grain boundary sulfur concentration corresponding to 50 pct transgranular and 50 pct intergranular fracture and P /SUB H2/ is the hydrogen pressure. The value of n was found to be between 0.34 and 0.9. This expression was derived by relating C /SUB s/ to th hydrogen overpotential with the Nernst equation. At a cathodic test potential of -0.3 V (SCE). C /SUB s/ was equal to 0.20 monolayers of sulfur and at higher cathodic potentials or higher hydrogen pressures, C /SUB s/ decreased such that at -0.72 V (SCE) C /SUB s/ was equal to 0.045 monolayers of sulfur. The inverse hydrogen pressure dependence observed with cathodic hydrogen is similar to that for the hydrogen permeation rate or a critical hydrogen concentration derived by Gerberich et al. for gaseous hydrogen. This similarity between gaseous and cathodic hydrogen suggests that grain boundary impurities contribute to the hydrogen embrittlement process without altering the embrittlement process although this result does not indicate whether decohesion or plasticity dependent processes are responsible for the combined sulfur-hydrogen effect on the intergranular fracture of nickel

  16. Hydrogen pressure dependence of the fracture mode transition in nickel

    International Nuclear Information System (INIS)

    Jones, R.H.; Baer, D.R.; Bruemmer, S.M.; Thomas, M.T.

    1983-01-01

    A relationship between fracture mode, grain boundary composition, and hydrogen pressure has been determined for nickel straining electrode samples tested at cathodic potentials. This relationship can be expressed as C /SUB S/ α P /SUP -n/ /SUB H2/ where C /SUB S/ is the critical grain boundary sulfur concentration corresponding to 50% transgranular and 50% intergranular fracture and P /SUB H2/ is the hydrogen pressure. The value of n was found to be between 0.34 and 0.9. This expression was derived by relating C /SUB S/ to the hydrogen overpotential with the Nernst equation. At a cathodic test potential of -0.3 V (SCE), C /SUB S/ was equal to 0.20 monolayers of sulfur and at higher cathodic potentials or higher hydrogen pressures, C /SUB S/ decreased such that at -0.72 V (SCE) C /SUB S/ was equal to 0.045 monolayers of sulfur. The inverse hydrogen pressure dependence observed with cathodic hydrogen is similar to that for the hydrogen permeation rate or a critical hydrogen concentration derived by Gerberich et al. for gaseous hydrogen. This similarity between gaseous and cathodic hydrogen suggests that grain boundary impurities contribute to the hydrogen embrittlement process without altering the embrittlement process although this result does not indicate whether decohesion or plasticity dependent processes are responsible for the combined sulfur-hydrogen effect on the intergranular fracture of nickel

  17. Mandible Fractures.

    Science.gov (United States)

    Pickrell, Brent B; Serebrakian, Arman T; Maricevich, Renata S

    2017-05-01

    Mandible fractures account for a significant portion of maxillofacial injuries and the evaluation, diagnosis, and management of these fractures remain challenging despite improved imaging technology and fixation techniques. Understanding appropriate surgical management can prevent complications such as malocclusion, pain, and revision procedures. Depending on the type and location of the fractures, various open and closed surgical reduction techniques can be utilized. In this article, the authors review the diagnostic evaluation, treatment options, and common complications of mandible fractures. Special considerations are described for pediatric and atrophic mandibles.

  18. Tensile properties and fracture mechanism of IN-100 superalloy in high temperature range

    Directory of Open Access Journals (Sweden)

    Milan T. Jovanović

    2017-06-01

    Full Text Available Tensile properties and fracture mechanism of a polycrystalline IN-100 superalloy have been investigated in the range from room temperature to 900°C. Optical microscopy (OM and transmission electron microscopy (TEM applying replica technique were used for microstructural investigation, whereas scanning electron microscopy (SEM was utilized for fracture study. High temperature tensile tests were carried out in vacuumed chamber. Results show that strength increases up to 700°C, and then sharply decreases with further increase in temperature. Elongation increases very slowly (6-7.5% till 500°C, then decreases to 4.5% at 900°C. Change in elongation may be ascribed to a change of fracture mechanism. Appearance of a great number of microvoids prevails up to 500°C resulting in a slow increase of elongation, whereas above this temperature elongation decrease is correlated with intergranular crystallographic fracture and fracture of carbides.

  19. Interocular suppression

    Science.gov (United States)

    Tuna, Ana Rita; Almeida Neves Carrega, Filipa; Nunes, Amélia Fernandes

    2017-08-01

    The objective of this work is to quantify the suppressive imbalance, based on the manipulation of ocular luminance, between a group of subjects with normal binocular vision and a group of subjects with amblyopia. The result reveals that there are statistically significant differences in interocular dominance between two groups, evidencing a greater suppressive imbalance in amblyopic subjects. The technique used, proved to be a simple, easy to apply and economic method, for quantified ocular dominance. It is presented as a technique with the potential to accompany subjects with a marked dominance in one of the eyes that makes fusion difficult.

  20. MicroRNA-137 dysregulation predisposes to osteoporotic fracture by impeding ALP activity and expression via suppression of leucine-rich repeat-containing G-protein-coupled receptor 4 expression.

    Science.gov (United States)

    Liu, Xiangjun; Xu, Xiaohui

    2018-08-01

    Osteoporosis is defined as a loss of bone mass and deterioration of its architecture resulting in bone weakness, which becomes prone to fracture. The objective of this study was to investigate the molecular mechanism by which miR-137 can reduce the risk of fracture in patients with osteoporosis. An online miRNA database and a luciferase reporter assay system were used to confirm that leucine-rich repeat-containing G-protein-coupled receptor 4 (LGR4) was the target of miR-137. Real-time PCR and western blot analysis were used to study miR-137 mRNA, the expression of LGR4 mRNA and protein among different groups or cells transfected with a scrambled miRNA control, miR-137 mimic, LGR4 siRNA and miR-137 inhibitor. Expression of miR-137 was upregulated to higher levels in cells isolated from osteoporosis patients with fracture than in those without fracture. The 'seed sequence' was found to be located within the 3' untranslated region (3'-UTR) of LGR4 mRNA by searching an online miRNA database. Luciferase reporter assay was performed to confirm that LGR4 is a direct target gene of miR-137 with a potential binding site in the 3'UTR of LGR4. Luciferase activity of cells transfected with wild-type LGR4 3'UTR was much lower than that of the cells transfected with mutant LGR4 3'UTR. The results of real-time PCR and immunohistochemistry experiments demonstrated that the expression levels of LGR4 mRNA and protein were much higher in osteoporosis patients with fracture than osteoporosis patients without fracture. We found that the expression levels of LGR4 mRNA and protein were clearly upregulated following transfection with miR-137 inhibitor, while noticeably downregulated following transfection with miR-137 mimic when compared with the scramble control. Furthermore, the expression of ALP mRNA and ALP activity in bone tissue were much higher in osteoporosis patients with fracture than those without fracture. In conclusion, these data prove that the overexpression of

  1. Microstructural-Scale Model for Surfaces Spreading of Intergranular Corrosion in Sensitized Stainless Steels and Aluminum-Magnesium (AA5XXX) Alloys

    Science.gov (United States)

    Jain, Swati

    Components from AA5XXX (Al-Mg alloys with more than 3 wt% Mg) alloys are X attractive due to availability of low cost, high strength to weight ratio and good weldability. Therefore, these alloys have potential applications in Naval ships. However, these alloys become susceptible to IGC (intergranular corrosion) due to beta-phase precipitation due to improper heat treatment or inadvertent thermal exposure. Stainless steels may also become susceptible due to carbide precipitation and chromium depletion on grain boundaries. IGC susceptibility depends on the interplay between the metallurgical conditions, electrochemical conditions, and chemical conditions. Specific combinations cause IGC while others do not. The objective of this study is to investigate the conditions which bring about surface spreading of IGC in these alloy classes. To accomplish this goal, a microstructure scale model was developed with experimental inputs to understand the 2-D IGC spreading in stainless steels and AA5XXX alloys. The conditions strongly affecting IGC spreading were elucidated. Upon natural and artificial aging, the stainless steels become susceptible to intergranular corrosion because of chromium depletion in the grain boundaries. After aging Al-Mg (AA5XXX) alloys show susceptibility due to the precipitation of the beta-phase (Al3Mg7) in the grain boundaries. Chromium depleted grain boundaries in stainless steels are anodically more active as compared to the interior of the grains. (3-phase rich grain boundaries have lower OCP (open circuit potential) and pitting potentials as compared to the Al-Mg solid solutions. A new approach to modeling the IGC surface spreading in polycrystalline materials that is presented. This model is the first to couple several factors into one granular scale model that illustrates the way in which they interact and IGC occurs. It sheds new information on conditions which cause IGC spreading in two alloy classes and describes a new theory for the critical

  2. Facial Fractures.

    Science.gov (United States)

    Ghosh, Rajarshi; Gopalkrishnan, Kulandaswamy

    2018-06-01

    The aim of this study is to retrospectively analyze the incidence of facial fractures along with age, gender predilection, etiology, commonest site, associated dental injuries, and any complications of patients operated in Craniofacial Unit of SDM College of Dental Sciences and Hospital. This retrospective study was conducted at the Department of OMFS, SDM College of Dental Sciences, Dharwad from January 2003 to December 2013. Data were recorded for the cause of injury, age and gender distribution, frequency and type of injury, localization and frequency of soft tissue injuries, dentoalveolar trauma, facial bone fractures, complications, concomitant injuries, and different treatment protocols.All the data were analyzed using statistical analysis that is chi-squared test. A total of 1146 patients reported at our unit with facial fractures during these 10 years. Males accounted for a higher frequency of facial fractures (88.8%). Mandible was the commonest bone to be fractured among all the facial bones (71.2%). Maxillary central incisors were the most common teeth to be injured (33.8%) and avulsion was the most common type of injury (44.6%). Commonest postoperative complication was plate infection (11%) leading to plate removal. Other injuries associated with facial fractures were rib fractures, head injuries, upper and lower limb fractures, etc., among these rib fractures were seen most frequently (21.6%). This study was performed to compare the different etiologic factors leading to diverse facial fracture patterns. By statistical analysis of this record the authors come to know about the relationship of facial fractures with gender, age, associated comorbidities, etc.

  3. Fracture sacrum.

    Directory of Open Access Journals (Sweden)

    Dogra A

    1995-04-01

    Full Text Available An extremely rare case of combined transverse and vertical fracture of sacrum with neurological deficit is reported here with a six month follow-up. The patient also had an L1 compression fracture. The patient has recovered significantly with conservative management.

  4. Fracture toughness measurements on a glass bonded sodalite high-level waste form

    International Nuclear Information System (INIS)

    DiSanto, T.; Goff, K. M.; Johnson, S. G.; O'Holleran, T. P.

    1999-01-01

    The electrometallurgical treatment of metallic spent nuclear fuel produces two high-level waste streams; cladding hulls and chloride salt. Argonne National Laboratory is developing a glass bonded sodalite waste form to immobilize the salt waste stream. The waste form consists of 75 Vol.% crystalline sodalite (containing the salt) with 25 Vol.% of an ''intergranular'' glassy phase. Microindentation fracture toughness measurements were performed on representative samples of this material using a Vickers indenter. Palmqvist cracking was confirmed by post-indentation polishing of a test sample. Young's modulus was measured by an acoustic technique. Fracture toughness, microhardness, and Young's modulus values are reported, along with results from scanning electron microscopy studies

  5. Fracture Mechanics

    CERN Document Server

    Zehnder, Alan T

    2012-01-01

    Fracture mechanics is a vast and growing field. This book develops the basic elements needed for both fracture research and engineering practice. The emphasis is on continuum mechanics models for energy flows and crack-tip stress- and deformation fields in elastic and elastic-plastic materials. In addition to a brief discussion of computational fracture methods, the text includes practical sections on fracture criteria, fracture toughness testing, and methods for measuring stress intensity factors and energy release rates. Class-tested at Cornell, this book is designed for students, researchers and practitioners interested in understanding and contributing to a diverse and vital field of knowledge. Alan Zehnder joined the faculty at Cornell University in 1988. Since then he has served in a number of leadership roles including Chair of the Department of Theoretical and Applied Mechanics, and Director of the Sibley School of Mechanical and Aerospace Engineering.  He teaches applied mechanics and his research t...

  6. Influence of Bone Remodeling Inhibition on the Development of Experimental Stress Fractures

    National Research Council Canada - National Science Library

    Schaffler, Mitchell B

    2005-01-01

    .... Using a bisphosphonate (BIS) to suppress remodeling in the rabbit tibial stress fracture model, we found that antiresorptive therapy reduced the intensity of the stress fracture response in this model...

  7. Numerical modelling in non linear fracture mechanics

    Directory of Open Access Journals (Sweden)

    Viggo Tvergaard

    2007-07-01

    Full Text Available Some numerical studies of crack propagation are based on using constitutive models that accountfor damage evolution in the material. When a critical damage value has been reached in a materialpoint, it is natural to assume that this point has no more carrying capacity, as is done numerically in the elementvanish technique. In the present review this procedure is illustrated for micromechanically based materialmodels, such as a ductile failure model that accounts for the nucleation and growth of voids to coalescence, and a model for intergranular creep failure with diffusive growth of grain boundary cavities leading to micro-crack formation. The procedure is also illustrated for low cycle fatigue, based on continuum damage mechanics. In addition, the possibility of crack growth predictions for elastic-plastic solids using cohesive zone models to represent the fracture process is discussed.

  8. Evolution of interphase and intergranular strain in zirconium-niobium alloys during deformation at room temperature

    Science.gov (United States)

    Cai, Song

    Zr-2.5Nb is currently used for pressure tubes in the CANDU (CANada Deuterium Uranium) reactor. A complete understanding of the deformation mechanism of Zr-2.5Nb is important if we are to accurately predict the in-reactor performance of pressure tubes and guarantee normal operation of the reactors. This thesis is a first step in gaining such an understanding; the deformation mechanism of ZrNb alloys at room temperature has been evaluated through studying the effect of texture and microstructure on deformation. In-situ neutron diffraction was used to monitor the evolution of the lattice strain of individual grain families along both the loading and Poisson's directions and to track the development of interphase and intergranular strains during deformation. The following experiments were carried out with data interpreted using elasto-plastic modeling techniques: (1) Compression tests of a 100%betaZr material at room temperature. (2) Tension and compression tests of hot rolled Zr-2.5Nb plate material. (3) Compression of annealed Zr-2.5Nb. (4) Cyclic loading of the hot rolled Zr-2.5Nb. (5) Compression tests of ZrNb alloys with different Nb and oxygen contents. The experimental results were interpreted using a combination of finite element (FE) and elasto-plastic self-consistent (EPSC) models. The phase properties and phase interactions well represented by the FE model, the EPSC model successfully captured the evolution of intergranular constraint during deformation and provided reasonable estimates of the critical resolved shear stress and hardening parameters of different slip systems under different conditions. The consistency of the material parameters obtained by the EPSC model allows the deformation mechanism at room temperature and the effect of textures and microstructures of ZrNb alloys to be understood. This work provides useful information towards manufacturing of Zr-2.5Nb components and helps in producing ideal microstructures and material properties for

  9. Effect of temperature on the elastic-plastic fracture toughness behavior of Inconel X-750

    International Nuclear Information System (INIS)

    Mills, W.J.

    1977-09-01

    The elastic-plastic J/sub Ic/ fracture toughness response of precipitation heat treated Inconel X-750 has been evaluated by the multi-specimen resistance curve (R-curve) technique at room temperature, 800 0 F (427 0 C), and 1000 0 F (538 0 C). The value of J/sub Ic/ for this nickel-base superalloy was found to be relatively independent of temperature over the test temperature range. On the other hand, the slopes of the fracture toughness R-curves were steeper at 800 and 1000 0 F (427 and 538 0 C) than at 75 0 F (24 0 C), thereby indicating that the resistance to crack extension was considerably greater at elevated temperatures, Metallographic and electron fractographic examination of the Inconel X-750 fracture surfaces revealed that this slope change phenomenon was associated with an intergranular to transgranular fracture mechanism transition. Under room temperature conditions, crack extension occurred primarily by an intergranular dimple rupture mechanism attributed to microvoid coalescence along a grain boundary denuded region. In the 800 to 1000 0 F (427 to 538 0 C) regime, the fracture surface was dominated by a faceted transgranular morphology

  10. Intergranular Corrosion of 316L Stainless Steel by Aging and UNSM (Ultrasonic Nano-crystal Surface Modification) treatment

    International Nuclear Information System (INIS)

    Lee, J. H.; Kim, Y. S.

    2015-01-01

    Austenitic stainless steels have been widely used in many engineering fields because of their high corrosion resistance and good mechanical properties. However, welding or aging treatment may induce intergranular corrosion, stress corrosion cracking, pitting, etc. Since these types of corrosion are closely related to the formation of chromium carbide in grain boundaries, the alloys are controlled using methods such as lowering the carbon content, solution heat treatment, alloying of stabilization elements, and grain boundary engineering. This work focused on the effects of aging and UNSM (Ultrasonic Nano-crystal Surface Modification) on the intergranular corrosion of commercial 316L stainless steel and the results are discussed on the basis of the sensitization by chromium carbide formation and carbon segregation, residual stress, grain refinement, and grain boundary engineering

  11. Development of seamless forged pipe and fitting for BWR recirculation loop piping with improved resistance to intergranular stress corrosion cracking

    International Nuclear Information System (INIS)

    Ohnishi, Keizo; Tsukada, Hisashi; Kobayashi, Masayoshi; Iwadate, Tadao; Ono, Shinichi

    1981-01-01

    As a primary remedy for IGSCC of primary loop piping, especially Recirculation Loop Piping of BWR, extra low carbon stainless steel with high nitrogen content has become to be used. While, in order to make In-service Inspection easier and complete, new design of piping which decrease both number and total length of weld line has been considered. Japan Steel Works has developed the research on large size seamless forged pipe and fitting made from high nitrogen extra low carbon 316 stainless steel. This paper describes the key points of manufacturing technology as well as the material properties, especially strength and intergranular-corrosion and intergranular- stress-corrosion-cracking-resistivities of these forged pipe and fitting. (author)

  12. Demonstration through EPR tests of the sensitivity of austeno-ferritic steels to intergranular corrosion and stress corrosion cracking

    International Nuclear Information System (INIS)

    Lopez, Nathalie

    1997-01-01

    Duplex stainless steels can be sensitised to intergranular corrosion and stress corrosion cracking (SCC) under some conditions (heat treatments, welding). The aim of this work is to contribute to the validation of the EPR (Electrochemical Potentiodynamic Reactivation) test in order to determine conditions for normalisation. This method, based on the dissolution of chromium depleted areas due to precipitation of σ-phase, provides a degree of sensitisation to intergranular corrosion. The test is broaden considering the mechanical stress by the way of slow strain rate tests, performed in chloride magnesium and in a solution similar to the EPR solution. A metallurgical study puts on the precipitates and the structural modifications due to welding and heat treatments, in order to make a critical analysis of the EPR test. (author) [fr

  13. Evaluation of intergranular cracks on the ring header cross at Grand Gulf Unit No. 1

    International Nuclear Information System (INIS)

    Czajkowski, C.J.

    1987-01-01

    A metallurgical investigation was performed on a sample of cracked ring header cross material from the Grand Gulf Unit No. 1 Nuclear Power Station. The cracks were located in a 6-7 in (15-17.5 cm) width band running circumferentially below the cross to cap weld with a similar band above the cross to discharger pipe weld. The indications were up to 19 mm in length and 6.0 mm in depth. This particular sample was cut from a cross which had not seen actual service but which had been used to qualify the induction heating stress improvement (IHSI) technique for the Grand Gulf units. The base material was SA 182 material manufactured to SA 403-type WP 304 stainless steel. The investigation consisted of visual/dye penetrant examination, chemical analysis, hardness testing, optical microscopy, scanning electron microscopy and energy dispersive spectroscopy. The evaluated cracks were intergranular and initiated on the forging's exterior surface. The grain size of the material was larger than ASTM 00 and no definitive corrosive species were found by Energy Dispersive Spectroscopy (EDS). The cracking is considered to be the result of the forging having been overheated/burned during manufacture. (author)

  14. The study on intergranular corrosion of sensitized Alloy 600 using DL-EPR and Huey method

    International Nuclear Information System (INIS)

    Lee, B. G.; Lee, H. R.; Kim, H. P.; Ryu, W. S.; Rhee, C. K.

    1998-01-01

    Intergranular corrosion(IGC) of sensitized Alloy 600 has been studied with double loop-electrochemical potentiokinetic reactivation(DL-EPR) and Huey tests. Corrosion of solution annealed Ni-XCr-10Fe(X=6∼15) alloys was also evaluated with DL-EPR and Huey methods to simulate corrosion of Cr-depleted grain boundary region of Alloy 600. Cr concentration of Cr-depleted grain boundary region of Alloy 600. Cr concentration profile across grain boundary was measured with TEM. In the range of the Cr concentration from 6 to 8%, corrosion rates of solution annealed Ni-XCr-10Fe(X=6∼15) alloys were much higher in Huey test than those in DL-EPR. But in the range of the Cr concentration from 12 to 15%, the trend was reversed. The width of IGC crack of Alloy 600 was higher in DL-EPR test than in Huey test in agreement with corrosion of solution annealed Ni-XCr-10Fe alloys. Width of IGC produced by DL-EPR test was almost uniform and wide while that produced by Huey test was sharp and marrow. These results suggest that IGC in DL-EPR test conforms to uniform dissolution model and IGC in Huey test conforms to Cr concentration dependent dissolution model

  15. Effect of boric acid on intergranular corrosion in tube support plate crevices

    International Nuclear Information System (INIS)

    Brunet, J.P.; Campan, J.L.

    1993-10-01

    Intergranular attack on steam generator tubing is one important phenomenon involved in availability of Pressurized Water Reactors. Boric acid appears to be a possible candidate for inhibiting the corrosion process. The program performed in Cadarache was supposed to give statistical informations on the boric acid effect. It was based on a large number of samples initially attacked during a program performed by BABCOCK ampersand WILCOX. These samples were sleeved onto Alloy 690 tubes, in order to prevent premature cracking. Unfortunately it was not possible to find chemical conditions able to produce significant additional corrosion; we postulated mainly due to a drastic reduction of the thermal flux resulting from the increase of the tube wall thickness under the tube support plates (TSP). The tests demonstrate that such sleeve could be a possible remedy of the corrosion when introduced under the TSP. The tests show indications of a possible beneficial effect of the boric acid, a large variability of the heats sensitivity to the IGA and a predominant effect of Na 2 CO 3 on IGA production

  16. Macro and intergranular stress responses of austenitic stainless steel to 90° strain path changes

    International Nuclear Information System (INIS)

    Gonzalez, D.; Kelleher, J.F.; Quinta da Fonseca, J.; Withers, P.J.

    2012-01-01

    Highlights: ► We measure and model the macro and IG stresses of ASS to 90° strain path changes. ► The macro stress–strain curves show a clear Bauschinger effect on reloading. ► This is only partially captured by the model. ► The measured {h k l} families show an earlier microyield than predicted. ► This difference is more noticeable for a strain path with a higher reversibility. - Abstract: Strain path history can play a crucial role in sensitising/desensitising metals to various damage mechanisms and yet little work has been done to quantify and understand how intergranular strains change upon path changes, or their effect on the macroscopic behaviour. Here we have measured, by neutron diffraction, and modelled, by crystal plasticity finite elements, the stress–strain responses of 316L stainless steel over three different 90° strain path changes using an assembled microstructure of randomly oriented crystallites. The measurements show a clear Bauschinger effect on reloading that is only partially captured by the model. Further, measurements of the elastic response of different {h k l} grain families revealed an even earlier onset of yield for strain paths reloaded in compression while a strain path reloaded in tension showed good agreement with corresponding predictions. Finally, we propose that the study of strain path effects provides a more rigorous test of crystal plasticity models than conventional in situ diffraction studies of uniaxial loading.

  17. Intergranular Corrosion Behavior of Low-Nickel and 304 Austenitic Stainless Steels

    Science.gov (United States)

    Bansod, Ankur V.; Patil, Awanikumar P.; Moon, Abhijeet P.; Khobragade, Nilay N.

    2016-09-01

    Intergranular corrosion (IGC) susceptibility for Cr-Mn austenitic stainless steel and 304 austenitic stainless steel (ASS) was estimated using electrochemical techniques. Optical and SEM microscopy studies were carried out to investigate the nature of IGC at 700 °C with increasing time (15, 30, 60, 180, 360, 720, 1440 min) according to ASTM standard 262 A. Quantitative analysis was performed to estimate the degree of sensitization (DOS) using double loop electrochemical potentiokinetic reactivation (DLEPR) and EIS technique. DLEPR results indicated that with the increase in thermal aging duration, DOS becomes more severe for both types of stainless steel. The DOS for Cr-Mn ASS was found to be higher (65.12% for 1440 min) than that of the AISI 304 ASS (23% for 1440 min). The higher degree of sensitization resulted in lowering of electrical charge capacitance resistance. Chronoamperometry studies were carried out at a passive potential of 0.4 V versus SCE and was observed to have a higher anodic dissolution of the passive film of Cr-Mn ASS. EDS studies show the formation of chromium carbide precipitates in the vicinity of the grain boundary. The higher Mn content was also observed for Cr-Mn ASS at the grain boundary.

  18. Status report: Intergranular stress corrosion cracking of BWR core shrouds and other internal components

    International Nuclear Information System (INIS)

    1996-03-01

    On July 25, 1994, the US Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 94-03 to obtain information needed to assess compliance with regulatory requirements regarding the structural integrity of core shrouds in domestic boiling water reactors (BWRs). This report begins with a brief description of the safety significance of intergranular stress corrosion cracking (IGSCC) as it relates to the design and function of BWR core shrouds and other internal components. It then presents a brief history of shroud cracking events both in the US and abroad, followed by an indepth summary of the industry actions to address the issue of IGSCC in BWR core shrouds and other internal components. This report summarizes the staff's basis for issuing GL 94-03, as well as the staff's assessment of plant-specific responses to GL 94-03. The staff is continually evaluating the licensee inspection programs and the results from examinations of BWR core shrouds and other internal components. This report is representative of submittals to and evaluations by the staff as of September 30, 1995. An update of this report will be issued at a later date

  19. The intergranular segregation of boron in substoichiometric Ni/sub 3/Al

    Energy Technology Data Exchange (ETDEWEB)

    Choudhury, A.

    1987-12-01

    The intermetallic compound Ni/sub 3/Al offers promise as a material for high temperature applications. In addition to its unusual property of increasing strength with temperature (until approx.700/sup 0/C), it has excellent corrosion and oxidation resistance. Microalloying the alloy with boron has been shown to be dramatically effective in improving its inherent intergranular brittleness. This improvement results from the strong tendency of boron to segregate to the grain boundaries of Ni/sub 3/Al. This research deals with the study of the segregation behavior of boron. Auger electron spectroscopy was chosen as the technique adopted to study this segregation. The strong effect of segregant level on the grain boundary strength level can be controlled by thermal history variations and by variations in the level of solute in the bulk. Cathodic hydrogen charging was shown to be a potent tool in opening up other wise cohesive boundaries for analysis. The effective binding energy of boron at the grain boundaries of Ni/sub 3/Al was calculated from experimental data; it was found to vary between 0.2 and 0.45 eV. Kinetics of segregation have been investigated; the present set of kinetic studies were shown to be inadequate to find a diffusion coefficient and that temperatures lower than those studied here need to be used. As an associated investigation, a set of elemental standards were developed for the particular scanning Auger microprobe used in this study. 141 refs., 94 figs., 26 tabs.

  20. Intergranular attack observed in radiation-enhanced corrosion of mild steel

    International Nuclear Information System (INIS)

    Reda, R.J.; Kelly, J.L.; Harna, S.L.A.

    1988-01-01

    Experiments were conducted to determine the effects of gamma radiation on the corrosion of AISI 1018 mild steel in deaerated brine solutions of various sodium, magnesium, and chloride ion concentrations. Immersed metal specimens were irradiated at an exposure rate of 3 x 10/sup 5/ R/h (0.3 MR/h) for up to 1250 h at a temperature of --25 C. The corrosion rates of the irradiated specimens were found to be roughly a factor of 10 greater than the rates for the non-irradiated specimens. The radiation-enhanced corrosion rate was also found to have increased with the chloride concentration. Electron micrographs revealed that the surface morphology of the specimens exposed to irradiated brines differed greatly from the non-irradiated specimens. The non-irradiated specimens had undergone uniform corrosion, while the irradiated specimens exhibited intergranular corrosion (IGC), a phenomenon not yet observed in mild steel. An explanation for this observation is offered in terms of the relative rates of formation and recombination of radiolytic species

  1. Intergranular fluid compositions from the Waste Isolation Pilot Plant (WIPP) southeastern New Mexico

    International Nuclear Information System (INIS)

    Krumhansl, J.L.; Kimball, K.M.; Stein, C.L.

    1991-01-01

    The objective of this study was to perform a systematic sampling of the intergranular brines that slowly ''weep'' from four of the main stratigraphic units exposed in the WIPP. This information was added to the data base on brine compositions used in performance assessment and also employed in characterizing Salado Formation hydrology at the repository horizon. Concentrations of Na, K, Mg, Ca, Cl, SO 4 , and Br were all highly variable. It was also established that this variability reflects neither post-excavation evaporation nor imprecision in the analytical techniques. Compositional variability on the length scale of a few tens of centimeters is as large as that found over several hundreds of meters. Stratigraphy did not appear to exert any control over weep brine compositions. Programmatically relevant applications of these results are: (1) a valid performance assessment must consider the possibility of a wide range of brines, rather than carry out evaluations using a single ''best'' average brine, and (2) the Salado appears not to function as a continuous aquifer since brines originating millions of years ago have failed to homogenize though separated by only short distances. 10 refs., 19 figs., 11 tabs

  2. Intergranular corrosion following friction stir welding of aluminum alloy 7075-T651

    Energy Technology Data Exchange (ETDEWEB)

    Lumsden, J.B.; Mahoney, M.W.; Pollock, G.; Rhodes, C.G.

    1999-12-01

    Friction stir welding (FSW), a relatively new solid-state joining process, is used to join Al alloys of all compositions, including alloys essentially considered unweldable. This study focused on microstructures in FSW Al alloy 7075-T651 (AA 7075-T651 [UNS 97075-T651]), an alloy not commonly fusion welded, and the resultant corrosion susceptibility. Although the heat input associated with FSW was relatively low and the time at temperature was short compared to fusion welding, localized microstructures, chemical segregation, and precipitate distributions were created that generally are not present in parent metal AA 7075-T651. Typically, in the weld and heat affected zone (HAZ), the times at peak temperature were short, cooling was relatively rapid, and peak temperatures were {lt} {approx}500 C. Accordingly, a corresponding microstructural gradient developed from the weld nugget into the unaffected parent metal with the precipitate distribution in and around grain boundaries reflecting this temperature excursion. Some of these microstructures, when exposed to a corrosive environment, showed selective grain boundary attack and a decrease in the pitting potential relative to the parent metal. A characterization of the microstructure and localized chemistry differences within the weld zones suggested that the decrease in corrosion resistance correlated with a depletion of Cu within the grain boundaries and precipitate-free zones. These results provided evidence that the lowered resistance to intergranular corrosion following FSW of AA 7075-T651 was caused by a difference in pitting potentials.

  3. Short intergranular cracks in the piecewise anisotropic continuum model of the microstructure

    International Nuclear Information System (INIS)

    Cizelj, L.; Kovse, I.

    2001-01-01

    Computational algorithms aiming at modeling and visualization of the initiation and growth of intergranular stress corrosion cracks (e.g., in the steam generator tubes) on the grain-size scale have already been proposed [6]. The main focus of the paper is given to the influence of randomly oriented neighboring grains on the microscopic stress fields at crack tips. The incompatibility strains, which develop along the boundaries of randomly oriented anisotropic grains, are shown to influence the local stress fields at crack tips significantly. Special attention has been paid to the implementation and comparison of different numerical methods estimating the local stress fields at crack tips, aiming at optimizing the computational time and the numerical accuracy of the results. The limited number of calculations indicate that the anisotropic arrangement of grains with local incompatibility strains causes on average about 10% (plane strain) and 26% (plane stress) higher J-integral values at the crack tips than expected from the calculations in the isotropic case.(author)

  4. Performance demonstration testing at the EPRI NDE center for intergranular stress corrosion cracking in BWR piping

    International Nuclear Information System (INIS)

    Pherigo, G.

    1986-01-01

    Intergranular stress corrosion cracking (IGSCC) has become a significant concern for the commercial electric utility industry during the past four years. As the IGSCC problem manifested itself, the Nuclear Regulatory Commission (NRC) responded by issuing Inspection and Enforcement (I and E) Bulletin 82-03 which required that ultrasonic inspection procedures be demonstrated on service- removed samples. The ability to reliably detect and discriminate IGSCC was recognized by the industry as a very difficult task, at best. Concurrent with the NRC bulletin, state-of-the-art yet practical techniques for the detection and discrimination of IGSCC had to be developed, demonstrated, and transferred to the field in a relatively short time. With the release of I and E Bulletin 83-02, procedures as well as personnel had to be qualified on service-removed samples. This paper reports how the EPRI Nondestructive Evaluation (NDE) Center developed the necessary technology and a formal training and qualification program to meet these needs on behalf of the industry

  5. Electrochemical Methods for the Intergranular Corrosion Property Evaluation of Stainless Steels

    International Nuclear Information System (INIS)

    Lee, Jung Bok

    1987-01-01

    For the last fifteen years, the Electrochemical Potentiokinetic Reactivation (EPR) method, an electrochemical method, has been actively investigated for use in determining the degree of sensitization (DOS) in stainless steels (a metallurgical structure susceptible to intergranular corrosion). One of the reasons for this active investigation was due to the fact that the technique may be usable for field nondestructive measurements of DOS in stainless steels. In this paper, a brief overview of the technique, including the advantages and limitations, is discussed. Then, a new test method which is able to detect the sensitized metallurgical structures nondestructively after field welding is introduced. This new nondestructive method is a modification of the ASTM A262-A (the oxalic acid etch test). The improved test method employs a 30 second etching in a 10% oxalic acid solution under an anodic current density of 1 ampere per square centimeter at the temperatures above 60 .deg. C. Between 50 and 60 .deg. C the thirty second etching test should be used first. When the thirty second etching shows an under etched grain boundary, the etching time should be increased to ninety seconds. At temperatures below 50 .deg. C the ninety second etching, as described in ASTM A 262-A, should be employed. This improved test method can be used in the temperature range of 0 and 100 .deg. C

  6. Direct visualization of β phase causing intergranular forms of corrosion in Al–Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Young-Ki, E-mail: deltag@naver.com; Allen, Todd

    2013-06-15

    For a more effective examination of microstructure in Al–Mg alloys, a new etching solution has been developed; dissolved ammonium persulfate in water. It is demonstrated how β phase (Al{sub 3}Mg{sub 2}) in Al–Mg alloys respond to this solution using samples of a binary Al–Mg alloy and a commercial 5083 aluminum alloy. Nanometer sized β phase is clearly visualized for the first time using scanning electron microscopy (SEM) instead of transmission electron microscopy (TEM). It is anticipated that direct and unambiguous visualization of β phase will greatly augment intergranular corrosion research in 5xxx series aluminum alloys. - Highlights: • Nanometer sized β phase in Al-10% Mg is first clearly visualized with SEM. • Nanometer sized β phase in wrought alloy 5083 is first clearly visualized with SEM. • Grain boundary decorating β phase and isolated sponge-like β phase are shown. • This phase is confirmed to be β phase using composition analysis.

  7. Fracture characteristic in creep of a 5 Cr-1/2 Mo steel at 600 and 6500C

    International Nuclear Information System (INIS)

    Paiva, R.L.C. de; Monteiro, S.N.; Silveira, T.L.

    The creep behavior of a 5 Cr-1/2 Mo steel was studied at 600 and 650 0 C. The caracteristics of fracture, observed by optical and scanning metallography, displayed a transition from intergranular to transgranular mode of rupture in the range of temperatures and stresses studied. This behavior was dicussed based upon the possible mechanisms for creep deformation taking place in this material [pt

  8. Intergranular stress study of TC11 titanium alloy after laser shock peening by synchrotron-based high-energy X-ray diffraction

    Science.gov (United States)

    Su, R.; Li, L.; Wang, Y. D.; Nie, Z. H.; Ren, Y.; Zhou, X.; Wang, J.

    2018-05-01

    The distribution of residual lattice strain as a function of depth were carefully investigated by synchrotron-based high energy X-ray diffraction (HEXRD) in TC11 titanium alloy after laser shock peening (LSP). The results presented big compressive residual lattice strains at surface and subsurface, then tensile residual lattice strains in deeper region, and finally close to zero lattice strains in further deep interior with no plastic deformation thereafter. These evolutions in residual lattice strains were attributed to the balance of direct load effect from laser shock wave and the derivative restriction force effect from surrounding material. Significant intergranular stress was evidenced in the processed sample. The intergranular stress exhibited the largest value at surface, and rapidly decreased with depth increase. The magnitude of intergranular stress was proportional to the severity of the plastic deformation caused by LSP. Two shocks generated larger intergranular stress than one shock.

  9. Determination of susceptibility to intergranular corrosion of stainless steels type X5CrNi18-10 in field

    Directory of Open Access Journals (Sweden)

    Bore V. Jegdic

    2016-12-01

    Full Text Available In this paper, the DL EPR method (electrochemical potentiokinetic reactivation with double loop was modified and used to study the susceptibility to intergranular corrosion and stress corrosion cracking of a stainless steel type X5CrNi18-10. The tests were performed in a special electrochemical cell, with the electrolyte in the gel form. Modified DL EPR method is characterized by simple and high accuracy measurements as well as repeatability of the test results. The indicator of susceptibility to intergranular corrosion (Qr/QpGBA obtained by modified DL EPR method is in a very good agreement with the same indicator obtained by standard DL EPR method. The modified DL EPR method is quantitative and highly selective method. Small differences in the susceptibility of the stainless steel type CrNi18-10 to intergranular corrosion and stress corrosion cracking can be determined. Test results can be obtained in a short time. The cost of tests performed by modified DL EPR method is much lower than the cost of tests by conventional chemical methods. Modified DL EPR method can be applied in the field on the stainless steels constructions.

  10. Effect of aging time on intergranular corrosion behavior of a newly developed LDX 2404 lean duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hui [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zhang, Ziying, E-mail: zzying@sues.edu.cn [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zhang, Huizhen [School of Management, University of Shanghai for Science and Technology, Shanghai 200093 (China); Hu, Jun [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Li, Jin [Department of Materials Science, Fudan University, Shanghai 200433 (China)

    2016-07-05

    The effect of aging at 700 °C for various times on the intergranular corrosion behavior of LDX 2404 duplex stainless steel is investigated by morphological observation and electrochemical detection. Scanning electronic microscopy and transmission electronic microscopy analysis reveal that Cr{sub 2}N, M{sub 23}C{sub 6} and the sigma and chi phases nucleate simultaneously at the initial stages of aging. The granular particles of sigma phase grow larger but fewer with the increase of aging time. The electrochemical detection results show that intergranular corrosion become more severe and the corrosion type evolves from intergranular corrosion into general corrosion as the holding time extends to 48 h. - Highlights: • The IGC behavior of aged LDX 2404 is investigated. • Cr{sub 2}N, M{sub 23}C{sub 6} and the σ and χ phases nucleate simultaneously at the initial stages of aging. • IGC resistance decreases with the increase of aging time. • The corrosion type evolves from IGC into general corrosion for longer aging times.

  11. Quantitative assessment of intergranular damage due to PWR primary water exposure in structural Ni-based alloys

    International Nuclear Information System (INIS)

    Ter-Ovanessian, Benoît; Deleume, Julien; Cloué, Jean-Marc; Andrieu, Eric

    2013-01-01

    Highlights: ► IG damage occurred on Ni-base alloys during exposure at high temperature water. ► Two characterization methods yield a tomographic analysis of this IG damage. ► Connected or isolated intergranular oxygen/oxide penetrations are quantified. ► Such quantitative description provides information on IGSCC susceptibility. - Abstract: Two nickel-based alloys, alloy 718 and alloy 600, known to have different resistances to IGSCC, were exposed to a simulated PWR primary water environment at 360 °C for 1000 h. The intergranular oxidation damage was analyzed in detail using an original approach involving two characterization methods (Incremental Mechanical Polishing/Microcopy procedure and SIMS imaging) which yielded a tomographic analysis of the damage. Intergranular oxygen/oxide penetrations occurred either as connected or isolated penetrations deep under the external oxide/substrate interface as far as 10 μm for alloy 600 and only 4 μm for alloy 718. Therefore, assessing this damage precisely is essential to interpret IGSCC susceptibility.

  12. Influence of C, N and Ti concentration on the intergranular corrosion resistance of AISI 316 Ti stainless steel

    International Nuclear Information System (INIS)

    Pardo, A.; Merino, M.C.; Carboneras, M.; Coy, A.E.; Viejo, F.; Arrabal, R.; Munoz, J.A.

    2004-01-01

    The influence of Ti, C, and N concentration on the intergranular corrosion resistance of AISI 316 Ti stainless steel has been studied. A kinetic study of the corrosion process has been carried out using gravimetric tests according to ASTM A-262 practices B and C (Streicher and Huey, respectively). The TTS diagrams were drawn as a function of alloying elements concentration (C, N and Ti). Materials characterization under several test conditions was carried out using Scanning Electron Microscopy (SEM) analysing microstructural characteristics and the attack microstructure. The chemical resistance of these steels to intergranular test was function of N, C and Ti concentration. High Ti and N concentration favoured the precipitation of TiN during the material manufacture process. N forms TiN very stable, causing the removal of Ti from the matrix and, indirectly, favouring the Cr 23 C 6 precipitation during the sensitization process and increasing the corrosion rate. In order to inhibit the intergranular corrosion in these materials the N and Ti concentrations must be optimised. (authors)

  13. The application of in situ analytical transmission electron microscopy to the study of preferential intergranular oxidation in Alloy 600

    Energy Technology Data Exchange (ETDEWEB)

    Burke, M.G., E-mail: m.g.burke@manchester.ac.uk; Bertali, G.; Prestat, E.; Scenini, F.; Haigh, S.J.

    2017-05-15

    In situ analytical transmission electron microscopy (TEM) can provide a unique perspective on dynamic reactions in a variety of environments, including liquids and gases. In this study, in situ analytical TEM techniques have been applied to examine the localised oxidation reactions that occur in a Ni-Cr-Fe alloy, Alloy 600, using a gas environmental cell at elevated temperatures. The initial stages of preferential intergranular oxidation, shown to be an important precursor phenomenon for intergranular stress corrosion cracking in pressurized water reactors (PWRs), have been successfully identified using the in situ approach. Furthermore, the detailed observations correspond to the ex situ results obtained from bulk specimens tested in hydrogenated steam and in high temperature PWR primary water. The excellent agreement between the in situ and ex situ oxidation studies demonstrates that this approach can be used to investigate the initial stages of preferential intergranular oxidation relevant to nuclear power systems. - Highlights: • In situ analytical TEM has been performed in 1 bar H{sub 2}-H{sub 2}O vapor at 360–480 °C. • Nanoscale GB migration and solute partitioning correlate with ex situ data for Alloy 600 in H{sub 2}-steam. • This technique can provide new insights into localised reactions associated with localised oxidation.

  14. Influence of C, N and Ti concentration on the intergranular corrosion resistance of AISI 316 Ti stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Pardo, A.; Merino, M.C.; Carboneras, M.; Coy, A.E.; Viejo, F.; Arrabal, R.; Munoz, J.A. [Departamento de Ciencia de Materiales, Facultad de Quimica, Universidad Complutense, 28040, Madrid (Spain)

    2004-07-01

    The influence of Ti, C, and N concentration on the intergranular corrosion resistance of AISI 316 Ti stainless steel has been studied. A kinetic study of the corrosion process has been carried out using gravimetric tests according to ASTM A-262 practices B and C (Streicher and Huey, respectively). The TTS diagrams were drawn as a function of alloying elements concentration (C, N and Ti). Materials characterization under several test conditions was carried out using Scanning Electron Microscopy (SEM) analysing microstructural characteristics and the attack microstructure. The chemical resistance of these steels to intergranular test was function of N, C and Ti concentration. High Ti and N concentration favoured the precipitation of TiN during the material manufacture process. N forms TiN very stable, causing the removal of Ti from the matrix and, indirectly, favouring the Cr{sub 23}C{sub 6} precipitation during the sensitization process and increasing the corrosion rate. In order to inhibit the intergranular corrosion in these materials the N and Ti concentrations must be optimised. (authors)

  15. Determination of the equivalent intergranular void ratio - Application to the instability and the critical state of silty sand

    Directory of Open Access Journals (Sweden)

    Nguyen Trung-Kien

    2017-01-01

    Full Text Available This paper presents an experimental study of mechanical response of natural Camargue silty sand. The analysis of test results used the equivalent intergranular void ratio instead of the global void ratio. The calculation of equivalent intergranular void ratio requires the determination of parameter b which represents, physically, the fraction of active fines participating on the chain forces network, hence the strength of the soil. A new formula for determining the parameter b by using an approach based on the coordination number distribution and probability calculation is proposed. The validation of the developed relationship was done through back-analysis of published datasets in literature on the effect of fines content on silty sand behavior. It is shown that the equivalent intergranular void ratio calculated with the b value obtained by the new formula is able to provide strong correlation to not only the critical state of but also the onset of instability of various silty sands, in different terms as peak deviator stress, peak stress ratio or cyclic resistance. Therefore, it is suggested that the use of the equivalent void ratio concept and the new b calculating formula is highly desirable in predicting of the silty sand behavior.

  16. The intergranular corrosion susceptibility of 2024 Al alloy during re–ageing after solution treating and cold–rolling

    International Nuclear Information System (INIS)

    Wang, Zhixiu; Chen, Peng; Li, Hai; Fang, Bijun; Song, Renguo; Zheng, Ziqiao

    2017-01-01

    Highlights: • No intergranular corrosion occured for the peak–re–aged and over–re–aged 2024 Al alloy. • Absence of intergranular corrosion in the re–aged samples resulted from no continuous grain boundary S–Al_2CuMg phase. • Aggregated pits were observed in the over–re–aged samples. • Aggregated pitting corrosion was related to the preferential precipitation of S–phase on the dislocation cell walls. - Abstract: The intergranular corrosion (IGC) susceptibility of 2024 Al alloy during re–ageing after solution treating and cold–rolling was investigated by accelerated corrosion testing, open circuit potential testing, transmission electron microscopy and scanning electron microscopy. The absence of IGC in both the peak–re–aged and over–re–aged samples is related to the dislocation pile–ups which prevent the supersaturated solutes from diffusing into the grain boundaries and precipitating the continuous S–Al_2CuMg phase. The aggregated pitting corrosion in the over–re–aged samples arises from the S–phase precipitates on the dislocation cell walls which accelerate the anodic dissolution of the cell interiors.

  17. In-reactor deformation and fracture of austenitic stainless steels

    International Nuclear Information System (INIS)

    Bloom, E.E.; Wolfer, W.G.

    1978-01-01

    An experimental technique for determining in-reactor fracture strain was developed and demonstrated. Differential swelling between a sample holder and a test specimen with a lower swelling rate produced uniaxial deformation. In-reactor deformations of 0.7 to 2.1% were achieved in type 304 stainless steel previously irradiated to fluences up to 8.8 x 10 26 n/m 2 without fracture. These strains are significantly higher than found in postirradiation creep-rupture tests on similar samples. From the measured strain values and published irradiation creep data and correlations, the stress levels during the irradiation were calculated. On the basis of previous postirradiation creep-rupture results, many of the samples that did not fail would be predicted to fail. Thus we conclude that the in-reactor rupture life is longer than predicted by postirradiation tests. Strain in a fractured sample was estimated to be less than 3.8%, and the in-reactor fractures were intergranular--the same fracture mode as found in postirradiation tests. Irradiation creep may relax stresses at crack tips and sliding boundaries, thus retarding the initiation and/or growth of cracks and leading to longer rupture lives in-reactor. However, the very high ductility or superplastic behavior predicted by the strain rate sensitivity of irradiation creep is not achieved because of the eventual interruption of the deformation process by grain boundary fracture

  18. Effect of clear bands on intergranular stresses and IASCC early damage - 04002

    International Nuclear Information System (INIS)

    Sauzay, M.; Ould Moussa, M.; Diawara, B.; Lebreau, F.

    2016-01-01

    Slip localization is a common feature in post-irradiated metallic poly-crystals undergoing tensile straining. This effect takes place for instance in the form of thin slip bands called channels or clear bands, formed after the local vanishing of irradiation defects induced interactions with gliding dislocations. Channel impingement towards grain boundaries (GBs) should induce local stress concentrations along GBs, in the quasi-elastic surrounding matrix. It has been shown extensively that this trigger GB crack initiation. Grain boundary fracture is simulated using a double criterion based on both critical normal stress and fracture energy as deduced from atomistic computations of GB fracture. The critical stress is deduced from the fracture energy using the universal-binding-energy relationship (UBER). In the case of brittle fracture, the fracture energy is defined as the two fresh free surface energy values minus the GB energy. In relationship with the more complex topic of irradiation induced stress corrosion cracking (IASCC) occurring in-service conditions, the influence of irradiation dose, strain rate and irradiation creep is discussed. Due to the complex loading history highlighted by structural finite element analysis, strain peaks may induce the formation of clear bands or twin bands. The study of the effect of irradiation creep on the relaxation of the induced GB stress fields shows clearly that the relaxation requires many months due to the linear irradiation creep law. Such durations allows GB oxidation mechanisms to occur leading to a weakening of the GB fracture parameters in the vicinity of the free surfaces. This short paper is followed by the slides of the presentation

  19. Local approach: fracture at high temperature in an austenitic stainless steel submitted to thermomechanical loadings. Calculations and experimental validations

    International Nuclear Information System (INIS)

    Poquillon, D.

    1997-10-01

    Usually, for the integrity assessment of defective components, well established rules are used: global approach to fracture. A more fundamental way to deal with these problems is based on the local approach to fracture. In this study, we choose this way and we perform numerical simulations of intergranular crack initiation and intergranular crack propagation. This type of damage can be find in components of fast breeder reactors in 316 L austenitic stainless steel which operate at high temperatures. This study deals with methods coupling partly the behaviour and the damage for crack growth in specimens submitted to various thermomechanical loadings. A new numerical method based on finite element computations and a damage model relying on quantitative observations of grain boundary damage is proposed. Numerical results of crack initiation and growth are compared with a number of experimental data obtained in previous studies. Creep and creep-fatigue crack growth are studied. Various specimen geometries are considered: compact Tension Specimens and axisymmetric notched bars tested under isothermal (600 deg C) conditions and tubular structures containing a circumferential notch tested under thermal shock. Adaptative re-meshing technique and/or node release technique are used and compared. In order to broaden our knowledge on stress triaxiality effects on creep intergranular damage, new experiments are defined and conducted on sharply notched tubular specimens in torsion. These isothermal (600 deg C) Mode II creep tests reveal severe intergranular damage and creep crack initiation. Calculated damage fields at the crack tip are compared with the experimental observations. The good agreement between calculations and experimental data shows the damage criterion used can improve the accuracy of life prediction of components submitted to intergranular creep damage. (author)

  20. Fracture mechanics

    CERN Document Server

    Perez, Nestor

    2017-01-01

    The second edition of this textbook includes a refined presentation of concepts in each chapter, additional examples; new problems and sections, such as conformal mapping and mechanical behavior of wood; while retaining all the features of the original book. The material included in this book is based upon the development of analytical and numerical procedures pertinent to particular fields of linear elastic fracture mechanics (LEFM) and plastic fracture mechanics (PFM), including mixed-mode-loading interaction. The mathematical approach undertaken herein is coupled with a brief review of several fracture theories available in cited references, along with many color images and figures. Dynamic fracture mechanics is included through the field of fatigue and Charpy impact testing. Explains computational and engineering approaches for solving crack-related problems using straightforward mathematics that facilitate comprehension of the physical meaning of crack growth processes; Expands computational understandin...

  1. Fracture analysis

    International Nuclear Information System (INIS)

    Ueng, Tzoushin; Towse, D.

    1991-01-01

    Fractures are not only the weak planes of a rock mass, but also the easy passages for the fluid flow. Their spacing, orientation, and aperture will affect the deformability, strength, heat transmittal, and fluid transporting properties of the rock mass. To understand the thermomechanical and hydrological behaviors of the rock surrounding the heater emplacement borehole, the location, orientation, and aperture of the fractures of the rock mass should be known. Borehole television and borescope surveys were performed to map the location, orientation, and aperture of the fractures intersecting the boreholes drilled in the Prototype Engineered Barrier System Field Tests (PEBSFT) at G-Tunnel. Core logging was also performed during drilling. However, because the core was not oriented and the depth of the fracture cannot be accurately determined, the results of the core logging were only used as reference and will not be discussed here

  2. Facial Fractures.

    Science.gov (United States)

    Ricketts, Sophie; Gill, Hameet S; Fialkov, Jeffery A; Matic, Damir B; Antonyshyn, Oleh M

    2016-02-01

    After reading this article, the participant should be able to: 1. Demonstrate an understanding of some of the changes in aspects of facial fracture management. 2. Assess a patient presenting with facial fractures. 3. Understand indications and timing of surgery. 4. Recognize exposures of the craniomaxillofacial skeleton. 5. Identify methods for repair of typical facial fracture patterns. 6. Discuss the common complications seen with facial fractures. Restoration of the facial skeleton and associated soft tissues after trauma involves accurate clinical and radiologic assessment to effectively plan a management approach for these injuries. When surgical intervention is necessary, timing, exposure, sequencing, and execution of repair are all integral to achieving the best long-term outcomes for these patients.

  3. Influence of the selected structural parameter on a depth of intergranular corrosion of Al-Si7-Mg0,3 aluminum alloy

    Directory of Open Access Journals (Sweden)

    L. Bernat

    2015-10-01

    Full Text Available The paper presents an influence of the Dendrite Arm Spacing (DAS microstructure parameter on the intergranular corrosion of AlSi7Mg aluminum alloy. The samples were subjected to the corrosion process for: 2,5; 12; 24; 48 and 96 hours in NaCl + HCl + H2O solution. It was noted that the DAS parameter significantly influenced on a distribution and depth of the intergranular corrosion of the hypoeutectic Al - Si - Mg silumin.

  4. Pisiform fractures

    International Nuclear Information System (INIS)

    Fleege, M.A.; Jebson, P.J.; Renfrew, D.L.; El-Khoury, G.Y.; Steyers, C.M. Jr.

    1991-01-01

    Fractures of the pisiform are often missed due to improper radiographic evaluation and a tendency to focus on other, more obvious injuries. Delayed diagnosis may result in disabling sequelae. A high index of clinical suspicion and appropriate radiographic examination will establish the correct diagnosis. Ten patients with pisiform fracture are presented. The anatomy, mechanism of injury, clinical presentation, radiographic features, and evaluation of this injury are discussed. (orig.)

  5. Stress fractures

    International Nuclear Information System (INIS)

    Berquist, T.H.; Cooper, K.L.; Pritchard, D.J.

    1985-01-01

    The diagnosis of a stress fracture should be considered in patients presented with pain after a change in activity, especially if the activity is strenuous and the pain is in the lower extremities. Since evidence of the stress fracture may not be apparent for weeks on routine radiographs, proper use of other imaging techniques will allow an earlier diagnosis. Prompt diagnosis is especially important in the femur, where displacement may occur

  6. Scaphoid Fracture

    Directory of Open Access Journals (Sweden)

    Esther Kim, BS

    2018-04-01

    Full Text Available History of present illness: A 25-year-old, right-handed male presented to the emergency department with left wrist pain after falling from a skateboard onto an outstretched hand two-weeks prior. He otherwise had no additional concerns, including no complaints of weakness or loss of sensation. On physical exam, there was tenderness to palpation within the anatomical snuff box. The neurovascular exam was intact. Plain films of the left wrist and hand were obtained. Significant findings: The anteroposterior (AP plain film of this patient demonstrates a full thickness fracture through the middle third of the scaphoid (red arrow, with some apparent displacement (yellow lines and subtle angulation of the fracture fragments (blue line. Discussion: The scaphoid bone is the most commonly fractured carpal bone accounting for 70%-80% of carpal fractures.1 Classically, it is sustained following a fall onto an outstretched hand (FOOSH. Patients should be evaluated for tenderness with palpation over the anatomical snuffbox, which has a sensitivity of 100% and specificity of 40%.2 Plain films are the initial diagnostic modality of choice and have a sensitivity of 70%, but are commonly falsely negative in the first two to six weeks of injury (false negative of 20%.3 The Mayo classification organizes scaphoid fractures as involving the proximal, mid, and distal portions of the scaphoid bone with mid-fractures being the most common.3 The proximal scaphoid is highly susceptible to vascular compromise because it depends on retrograde blood flow from the radial artery. Therefore, disruption can lead to serious sequelae including osteonecrosis, arthrosis, and functional impairment. Thus, a low threshold should be maintained for neurovascular evaluation and surgical referral. Patients with non-displaced scaphoid fractures should be placed in a thumb spica splint.3 Patients with even suspected scaphoid fractures should be placed in a thumb spica splint and re

  7. Intergranular corrosion testing of austenitic stainless steels in nitric acid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Whillock, G.O.H.; Dunnett, B. F. [British Nuclear Fuels plc, BNFL, B170, Sellafield, Seascale, Cumbria CA20 1PG (United Kingdom)

    2004-07-01

    In hot strong nitric acid solutions, stainless steels exhibit intergranular corrosion. Corrosion rates are often measured from immersion testing of specimens manufactured from the relevant material (e.g. plate or pipe). The corrosion rates, measured from weight loss, are found to increase with time prior to reaching steady state, which can take thousands of hours to achieve. The apparent increase in corrosion rate as a function of time was found to be an artefact due to the surface area of the specimen's being used in the corrosion rate calculations, rather than that of the true area undergoing active corrosion i.e. the grain boundaries. The steady state corrosion rate coincided with the onset of stable grain dropping, where the use of the surface area of the specimen to convert the weight loss measurements to corrosion rates was found to be appropriate. This was confirmed by sectioning of the specimens and measuring the penetration depths. The rate of penetration was found to be independent of time and no induction period was observed. A method was developed to shorten considerably the testing time to reach the steady state corrosion rate by use of a pre-treatment that induces grain dropping. The long-term corrosion rates from specimens which were pre-treated was similar to that achieved after prolonged testing of untreated (i.e. initially ground) specimens. The presence of cut surfaces is generally unavoidable in the simple immersion testing of specimens in test solutions. However, inaccuracy in the results may occur as the measured corrosion rate is often influenced by the orientation of the microstructure, the highest rates typically being observed on the cut surfaces. Two methods are presented which allow deconvolution of the corrosion rates from immersion testing of specimens containing cut surfaces, thus allowing reliable prediction of the long-term corrosion rate of plate surfaces. (authors)

  8. The fate of benzotriazole pollutants in an urban oxic intergranular aquifer.

    Science.gov (United States)

    Trček, Branka; Žigon, Dušan; Zidar, Vlasta Kramarič; Auersperger, Primož

    2017-12-26

    Benzotriazoles (BTs) are considered as Contaminants of Emerging Concern (CECs); however, information about their fate in aquifers continues to be absent. This was the focus of the present study, which provides the first evidence for relevant BTs' degradation products (BTTPs) in urban aquifers that may impact the groundwater quality. The mechanisms and biotransformation pathways of BTs were investigated in an oxic intergranular medium. The BTs and BTTPs were identified and quantified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) analytical techniques based on reference standards and internal materials. The major transformation products were identified as 2-methyl-2H-benzotriazole (2-MeBT) for the degradation of 1H-benzotriazole (BT) and as 2,4-dimethyl-2H-benzotriazole (2,4-dMeBT) and 1,4-dimethyl-1H-benzotriazole (1,4-dMeBT) for the degradation of 4-methyl-1H-benzotriazole (4-MeBT), and most probably also 5-methyl-1H-benzotriazole (5-MeBT). The leakage of wastewater pipelines is most probably the source of BTs. Sediments with a lower hydraulic conductivity give rise to perched aquifer conditions that lead to the temporal storage of leaking effluents and presumably the majority of BTs' transformation processes via methylation and tautomerization. The most stable BTTPs entered the saturated zone of the aquifer, where they prevailed. Concentrations up to 1500 ng L -1 were measured for the 2,4-dMeBT, which suggest a contamination risk for groundwater that is or may be used as a source for drinking water in the case of a constant input of pollutant loads from sewer systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Effect of the build orientation on the mechanical properties and fracture modes of SLM Ti–6Al–4V

    Energy Technology Data Exchange (ETDEWEB)

    Simonelli, M., E-mail: M.Simonelli@lboro.ac.uk [Department of Materials, Loughborough University, Loughborough LE11 3TU (United Kingdom); Tse, Y.Y. [Department of Materials, Loughborough University, Loughborough LE11 3TU (United Kingdom); Tuck, C. [Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering, The University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2014-10-20

    Recent research on the additive manufacturing (AM) of Ti alloys has shown that the mechanical properties of the parts are affected by the characteristic microstructure that originates from the AM process. To understand the effect of the microstructure on the tensile properties, selective laser melted (SLM) Ti–6Al–4V samples built in three different orientations were tensile tested. The investigated samples were near fully dense, in two distinct conditions, as-built and stress relieved. It was found that the build orientation affects the tensile properties, and in particular the ductility of the samples. The mechanical anisotropy of the parts was discussed in relation to the crystallographic texture, phase composition and the predominant fracture mechanisms. Fractography and electron backscatter diffraction (EBSD) results indicate that the predominant fracture mechanism is intergranular fracture present along the grain boundaries and thus provide and explain the typical fracture surface features observed in fracture AM Ti–6Al–4V.

  10. Effect of the build orientation on the mechanical properties and fracture modes of SLM Ti–6Al–4V

    International Nuclear Information System (INIS)

    Simonelli, M.; Tse, Y.Y.; Tuck, C.

    2014-01-01

    Recent research on the additive manufacturing (AM) of Ti alloys has shown that the mechanical properties of the parts are affected by the characteristic microstructure that originates from the AM process. To understand the effect of the microstructure on the tensile properties, selective laser melted (SLM) Ti–6Al–4V samples built in three different orientations were tensile tested. The investigated samples were near fully dense, in two distinct conditions, as-built and stress relieved. It was found that the build orientation affects the tensile properties, and in particular the ductility of the samples. The mechanical anisotropy of the parts was discussed in relation to the crystallographic texture, phase composition and the predominant fracture mechanisms. Fractography and electron backscatter diffraction (EBSD) results indicate that the predominant fracture mechanism is intergranular fracture present along the grain boundaries and thus provide and explain the typical fracture surface features observed in fracture AM Ti–6Al–4V

  11. Trochanteric fractures

    International Nuclear Information System (INIS)

    Herrlin, K.; Stroemberg, T.; Lidgren, L.; Walloee, A.; Pettersson, H.; Lund Univ.

    1988-01-01

    Four hundred and thirty trochanteric factures operated upon with McLaughlin, Ender or Richard's osteosynthesis were divided into 6 different types based on their radiographic appearance before and immediately after reposition with special reference to the medial cortical support. A significant correlation was found between the fracture type and subsequent mechanical complications where types 1 and 2 gave less, and types 4 and 5 more complications. A comparison of the various osteosyntheses showed that Richard's had significantly fewer complications than either the Ender or McLaughlin types. For Richard's osteosynthesis alone no correlation to fracture type could be made because of the small number of complications in this group. (orig.)

  12. Fracture Blisters

    Directory of Open Access Journals (Sweden)

    Uebbing, Claire M

    2011-02-01

    Full Text Available Fracture blisters are a relatively uncommon complication of fractures in locations of the body, such as the ankle, wrist elbow and foot, where skin adheres tightly to bone with little subcutaneous fat cushioning. The blister that results resembles that of a second degree burn.These blisters significantly alter treatment, making it difficult to splint or cast and often overlying ideal surgical incision sites. Review of the literature reveals no consensus on management; however, most authors agree on early treatment prior to blister formation or delay until blister resolution before attempting surgical correction or stabilization. [West J Emerg Med. 2011;12(1;131-133.

  13. Intergranular corrosion of 13Cr and 17Cr martensitic stainless steels in accelerated corrosive solution and high-temperature, high-purity water

    International Nuclear Information System (INIS)

    Ozaki, Toshinori; Ishikawa, Yuichi

    1988-01-01

    Intergranular corrosion behavior of 13Cr and 17Cr martensitic stainless steels was studied by electrochemical and immersing corrosion tests. Effects of the mEtallurgical and environmental conditions on the intergranular corrosion of various tempered steels were examined by the following tests and discussed. (a) Anodic polarization measurement and electrolytical etching test in 0.5 kmol/m 3 H 2 SO 4 solution at 293 K. (b) Immersion corrosion test in 0.88 kmol/m 3 HNO 3 solution at 293 K. (c) Long-time immersion test for specimens with a crevice in a high purity water at 473 K∼561 K. It was found from the anodic polarization curves in 0.5 kmol/m 3 H 2 SO 4 solution-at 293 K that the steels tempered at 773∼873 K had susceptibility to intergranular corrosion in the potential region indicating a second current maximum (around-0.1 V. vs. SCE). But the steel became passive in the more noble potential region than the second current peak potential, while in the less noble potential region general corrosion occurred independent of its microstructure. The intergranular corrosion occurred due to the localized dissolution along the pre-austenitic grain boundary and the martensitic lath boundary. It could be explained by the same dissolution model of the chromium depleted zone as proposed for the intergranular corrosion of austenitic and ferritic stainless steels. The intergranular corrosion occurred entirely at the free surface in 0.88 kmol/m 3 HNO 3 solution, while in the high temperature and high purity water only the entrance of the crevice corroded. It was also suggested that this intergranular corrosion might serve as the initiation site for stress corrosion cracking of the martensitic stainless steel. (author)

  14. First-principles study of the effects of halogen dopants on the properties of intergranular films in silicon nitride ceramics

    International Nuclear Information System (INIS)

    Painter, Gayle S.; Becher, Paul F.; Kleebe, H.-J.; Pezzotti, G.

    2002-01-01

    The nanoscale intergranular films that form in the sintering of ceramics often occur as adherent glassy phases separating the crystalline grains in the ceramic. Consequently, the properties of these films are often equal in importance to those of the constituent grains in determining the ceramic's properties. The measured characteristics of the silica-rich phase separating the crystalline grains in Si 3 N 4 and many other ceramics are so reproducible that SiO 2 has become a model system for studies of intergranular films (IGF's). Recently, the influence of fluorine and chlorine dopants in SiO 2 -rich IGF's in silicon nitride was precisely documented by experiment. Along with the expected similarities between the halogens, some dramatically contrasting effects were found. But the atomic-scale mechanisms distinguishing the effects F and Cl on IGF behavior have not been well understood. First-principles density functional calculations reported here provide a quantum-level description of how these dopant-host interactions affect the properties of IGF's, with specific modeling of F and Cl in the silica-rich IGF in silicon nitride. Calculations were carried out for the energetics, structural changes, and forces on the atoms making up a model cluster fragment of an SiO 2 intergranular film segment in silicon nitride with and without dopants. Results show that both anions participate in the breaking of bonds within the IGF, directly reducing the viscosity of the SiO 2 -rich film and promoting decohesion. Observed differences in the way fluorine and chlorine affect IGF behavior become understandable in terms of the relative stabilities of the halogens as they interact with Si atoms that have lost one if their oxygen bridges

  15. Elbow Fractures

    Science.gov (United States)

    ... is also an important factor when treating elbow fractures. Casts are used more frequently in children, as their risk of developing elbow stiffness is small; however, in an adult, elbow stiffness is much more likely. Rehabilitation directed by your doctor is often used to ...

  16. Wrist Fractures

    Science.gov (United States)

    ... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Wrist Fractures Email to a friend * required fields ...

  17. Shoulder Fractures

    Science.gov (United States)

    ... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Shoulder Fractures Email to a friend * required fields ...

  18. Intergranular corrosion in AA5XXX aluminum alloys with discontinuous precipitation at the grain boundaries

    Science.gov (United States)

    Bumiller, Elissa

    The US Navy currently uses AA5xxx aluminum alloys for structures exposed to a marine environment. These alloys demonstrate excellent corrosion resistance over other aluminum alloys (e.g., AA2xxx or AA7xxx) in this environment, filling a niche in the marine structures market when requiring a light-weight alternative to steel. However, these alloys are susceptible to localized corrosion; more specifically, intergranular corrosion (IGC) is of concern. IGC of AA5xxx alloys due to the precipitation of beta phase on the grain boundaries is a well-established phenomenon referred to as sensitization. At high degrees of sensitization, the IGC path is a continuous anodic path of beta phase particles. At lower degrees of sensitization, the beta phase coverage at the grain boundaries is not continuous. The traditional ranges of susceptibility to IGC as defined by ASTM B928 are in question due to recent studies. These studies showed that even at mid range degrees of sensitization where the beta phase is no longer continuous, IGC may still occur. Previous thoughts on IGC of these alloy systems were founded on the idea that once the grain boundary precipitate became discontinuous the susceptibility to IGC was greatly reduced. Additionally, IGC susceptibility has been defined metallurgically by compositional gradients at the grain boundaries. However, AA5xxx alloys show no compositional gradients at the grain boundaries, yet are still susceptible to IGC. The goal of this work is to establish criteria necessary for IGC to occur given no continuous beta phase path and no compositional gradient at the grain boundaries. IGC performance of the bulk alloy system AA5083 has been studied along with the primary phases present in the IGC system: alpha and beta phases using electrochemistry and modeling as the primary tools. Numerical modeling supports that at steady-state the fissure tip is likely saturated with Mg in excess of the 4% dissolved in the matrix. By combining these results

  19. ZEISIG: Approximate calculation of the intergranular gas fraction and the intragranular gas driven swelling for SAS4A

    International Nuclear Information System (INIS)

    Vaeth, L.

    1993-02-01

    A simple model has been developed for estimating, under steady-state irradiation conditions and for operational transients, the fraction of intergranular gas residing in fast reactor fuel and the intragranular gas driven swelling. The total gas retention in the fuel, the grain size and the irradiation conditions (mainly time dependent temperatures) must be known. Use has been made of parts of the fission gas model contained in the code LAKU and of results calculated with this code. The routine (named ZEISIG) is intended for insertion into the fast reactor accident model SAS4A as an extension of its fission gas model for steady-state reactor operation. (orig.) [de

  20. MR imaging of scaphoid fractures

    DEFF Research Database (Denmark)

    Meincke, Louise; Radev, Dimitar; Eriksen, Rie Østbjerg

    2017-01-01

    the importance of early MRI and hereby predict bone bruise with the help of fat suppression sequence; however, only a limited selection articles compares various fat suppression techniques. The purpose of this prospective study was to compare the short tau inversion recovery (STIR) and T2 fat saturation (FAT SAT......) sequences, sectional directed along the scaphoid bone axis. In relation to background fat intensity suppression, this study sought the sequence that best evaluated posttraumatic bone marrow edema (bone bruise) on scaphoid injury musculoskeletal magnetic resonance imaging (MRI, 1.5 T extremity scanner......). Materials and methods: Two hundred and fifty-one patients with relevant trauma and positive clinical test for scaphoid bone fractures, exceeding no more than 14 days, underwent MRI examinations. A fast STIR and T2 FAT SAT fast spin echo sequence (FSE) were obtained using a comparable parameter setting (scan...

  1. Effect of irradiation and chemical composition on deformation and fracture of steel of OH16N15 type during long-term test

    International Nuclear Information System (INIS)

    Averin, S.A.; Deniskin, Yu.S.; Shushlebin, V.V.; Panchenko, V.L.

    1992-01-01

    Thermal and radiation creep, as well as long-term strength of an austenitic stainless steel were investigated as a function of sulphur content and niobium addition. Interrelation between the grain boundary sleep and the intergranular fracture, and an important role of the surface in the nucleation and propagation of crack were revealed by quantitative structural and fractographic studies. Irradiation and chemical composition were found to influence these processes

  2. Bimalleolar ankle fracture with proximal fibular fracture

    NARCIS (Netherlands)

    Colenbrander, R. J.; Struijs, P. A. A.; Ultee, J. M.

    2005-01-01

    A 56-year-old female patient suffered a bimalleolar ankle fracture with an additional proximal fibular fracture. This is an unusual fracture type, seldom reported in literature. It was operatively treated by open reduction and internal fixation of the lateral malleolar fracture. The proximal fibular

  3. Fracture mechanics

    International Nuclear Information System (INIS)

    Miannay, D.P.

    1995-01-01

    This book entitle ''Fracture Mechanics'', the first one of the monograph ''Materiologie'' is geared to design engineers, material engineers, non destructive inspectors and safety experts. This book covers fracture mechanics in isotropic homogeneous continuum. Only the monotonic static loading is considered. This book intended to be a reference with the current state of the art gives the fundamental of the issues under concern and avoids the developments too complicated or not yet mastered for not making reading cumbersome. The subject matter is organized as going from an easy to a more complicated level and thus follows the chronological evolution in the field. Similarly the microscopic scale is considered before the macroscopic scale, the physical understanding of phenomena linked to the experimental observation of the material preceded the understanding of the macroscopic behaviour of structures. In this latter field the relatively recent contribution of finite element computations with some analogy with the experimental observation is determining. However more sensitive analysis is not skipped

  4. The Effect of MoO42- Addition on the Intergranular Corrosion Behavior of Sensitized type 304 Stainless Steel

    International Nuclear Information System (INIS)

    Lee, Kee Pyo; Kim, Kwan Hyu

    1988-01-01

    This experiment is aimed at the investigation of the effect of MoO 4 2- added to the electrolyte on the corrosion behavior of sensitized 304 stainless steel. The specimens of 304 stainless steel were sensitized for 1 hour at 800 .deg. C, and also for 1 hour at 800 .deg. C followed by 600 .deg. C for 2 hours. Polarization curves of the specimens were obtained in 1N H 2 SO 4 + 0.2N NCl (with or without 0.001M MoO 4 2- ) and in 1N H 2 SO 4 + 0.01N KSCN (with or without 0.001M MoO 4 2- )solutions. All specimens after corrosion test were subjected to microstructural analysis by using an optical microscope. The susceptibility of 304 stainless steel to the intergranular corrosion was decreased by the addition of MoO 4 2- to the electrolyte. It is suggested that the MoO 4 2- in the electrolyte leads to the easy formation of a passive film on the stainless steel substrate. It was confirmed that the area of intergranular attack of stainless steel was decreased by the addition of MoO 4 2- to the electrolyte

  5. Influence of Ti, C and N concentration on the intergranular corrosion behaviour of AISI 316Ti and 321 stainless steels

    International Nuclear Information System (INIS)

    Pardo, A.; Merino, M.C.; Coy, A.E.; Viejo, F.; Carboneras, M.; Arrabal, R.

    2007-01-01

    Intergranular corrosion behaviour of 316Ti and 321 austenitic stainless steels has been evaluated in relation to the influence exerted by modification of Ti, C and N concentrations. For this evaluation, electrochemical measurements - double loop electrochemical potentiokinetic reactivation (DL-EPR) - were performed to produce time-temperature-sensitization (TTS) diagrams for tested materials. Transmission (TEM) and scanning electron microscopy (SEM) were used to determine the composition and nature of precipitates. The addition of Ti promotes better intergranular corrosion resistance in stainless steels. The precipitation of titanium carbides reduces the formation of chromium-rich carbides, which occurs at lower concentrations. Also, the reduction of carbon content to below 0.03 wt.% improves sensitization resistance more than does Ti content. The presence of Mo in AISI 316Ti stainless steel reduces chromium-rich carbide precipitation; the reason is that Mo increases the stability of titanium carbides and tends to replace chromium in the formation of carbides and intermetallic compounds, thus reducing the risks of chromium-depletion

  6. Standard Test Methods for Detecting Susceptibility to Intergranular Corrosion in Wrought, Nickel-Rich, Chromium-Bearing Alloys

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 These test methods cover two tests as follows: 1.1.1 Method A, Ferric Sulfate-Sulfuric Acid Test (Sections 3-10, inclusive)—This test method describes the procedure for conducting the boiling ferric sulfate—50 % sulfuric acid test which measures the susceptibility of certain nickel-rich, chromium-bearing alloys to intergranular corrosion (see Terminology G 15), which may be encountered in certain service environments. The uniform corrosion rate obtained by this test method, which is a function of minor variations in alloy composition, may easily mask the intergranular corrosion components of the overall corrosion rate on alloys N10276, N06022, N06059, and N06455. 1.1.2 Method B, Mixed Acid-Oxidizing Salt Test (Sections 11-18, inclusive)—This test method describes the procedure for conducting a boiling 23 % sulfuric + 1.2 % hydrochloric + 1 % ferric chloride + 1 % cupric chloride test which measures the susceptibility of certain nickel-rich, chromium-bearing alloys to display a step function increa...

  7. Effect of helium bubbles at grain boundaries on the fracture characteristics of high-density 238PuO2

    International Nuclear Information System (INIS)

    Sisson, R.D.; McDonell, W.R.

    1976-01-01

    Helium bubbles that formed at grain boundaries in high density (greater than 92 percent of theoretical) 238 PuO 2 shards did not affect the room temperature fracture behavior as observed by scanning electron microscopy. Fracture was predominantly by brittle transgranular cleavage with only infrequent intergranular failure observed. Pores (approximately 5 μm dia) that formed within the grains during the sintering process, rather than helium bubbles, initiated fractures. Helium bubbles were observed occasionally on the fracture surfaces of 20-month-old shards that had been heated to 1600 0 C for 8 h and subsequently crushed at room temperature. The average radius of these bubbles was approximately 1 μm. These bubbles were not interconnected, but were sometimes aligned in stringers

  8. An Electrochemical Framework to Explain Intergranular Stress Corrosion Cracking in an Al-5.4%Cu-0.5%Mg-0.5%Ag Alloy

    Science.gov (United States)

    Little, D. A.; Connolly, B. J.; Scully, J. R.

    2001-01-01

    A modified version of the Cu-depletion electrochemical framework was used to explain the metallurgical factor creating intergranular stress corrosion cracking susceptibility in an aged Al-Cu-Mg-Ag alloy, C416. This framework was also used to explain the increased resistance to intergranular stress corrosion cracking in the overaged temper. Susceptibility in the under aged and T8 condition is consistent with the grain boundary Cu-depletion mechanism. Improvements in resistance of the T8+ thermal exposure of 5000 h at 225 F (T8+) compared to the T8 condition can be explained by depletion of Cu from solid solution.

  9. Ductility and fracture behavior of polycrystalline Ni/sub 3/Al alloys

    International Nuclear Information System (INIS)

    Liu, C.T.

    1987-01-01

    This paper provides a comprehensive review of the recent work on tensile ductility and fracture behavior of Ni/sub 3/Al alloys tested at ambient and elevated temperatures. Polycrystalline Ni/sub 3/Al is intrinsically brittle along grain boundaries, and the brittleness has been attributed to the large difference in valency, electronegativity, and atom size between nickel and aluminum atoms. Alloying with B, Mn, Fe, and Be significantly increases the ductility and reduces the propensity for intergranular fracture in Ni/sub 3/Al alloys. Boron is found to be most effective in improving room-temperature ductility of Ni/sub 3/Al with <24.5 at.% Al. The tensile ductility of Ni/sub 3/Al alloys depends strongly on test environments at elevated temperatures, with much lower ductilities observed in air than in vacuum. The loss in ductility is accompanied by a change in fracture mode from transgranular to intergranular. This embrittlement is due to a dynamic effect involving simultaneously high localized stress, elevated temperature, and gaseous oxygen. The embrittlement can be alleviated by control of grain shape or alloying with chromium additions. All the results are discussed in terms of localized stress concentration and grain-boundary cohesive strength

  10. Fracture properties of polycrystalline YBa2Cu3Ox

    International Nuclear Information System (INIS)

    Cook, R.F.; Shaw, T.M.; Duncombe, P.R.

    1987-01-01

    Polycrystalline YBa 2 Cu 3 O x has been prepared by sintering pre-reacted powder in oxygen to yield a material with 15 μm grain size, 86% relative density and which superconducts above liquid nitrogen temperatures. Indentation crack length measurements give a toughness K c = 1.3 ± 0.2 MPa m 1/2 , above a threshold contact load for radial crack initiation of approximately 5 N (compared with 1.1 MPa m 1/2 and < 0.1 N, respectively, for single crystals). The increased toughness and threshold contact load are controlled by the deviation of cracks from the plane of maximum driving force for fracture by weak grain boundaries and preferred fracture planes within grains. Optical microscopy of indentation cracks and scanning electron microscopy of fracture surfaces reveals approximately 50% intergranular fracture. The hardness of the polycrystal was H = 2.0 ± 0.5 GPa (compared with 8.7 GPa for single crystals). The decreased hardness arises from the porosity of the polycrystalline material and grain boundary sliding under the indentation contact. Time dependent growth of lateral cracks at the indentation contacts suggests that these materials are susceptible to moisture controlled non-equilibrium crack growth

  11. Hip fracture - discharge

    Science.gov (United States)

    ... neck fracture repair - discharge; Trochanteric fracture repair - discharge; Hip pinning surgery - discharge ... in the hospital for surgery to repair a hip fracture, a break in the upper part of ...

  12. Study of Aging-Induced Degradation of Fracture Resistance of Alloy 617 Toward High-Temperature Applications

    Science.gov (United States)

    Singh, Aditya Narayan; Moitra, A.; Bhaskar, Pragna; Sasikala, G.; Dasgupta, Arup; Bhaduri, A. K.

    2017-07-01

    For the Alloy 617, the effect of aging on the fracture energy degradation has been investigated after aging for different time periods at 1023 K (750 °C). A sharp reduction in impact energy (by 55 pct vis-à-vis the as-received material) after 1000 hours of aging, as evaluated from room-temperature Charpy impact tests, has been observed. Further aging up to 10,000 hours has led to a degradation of fracture energy up to 78 pct. Fractographic examinations using scanning electron microscopy (SEM) have revealed a change in fracture mode from fibrous-ductile for the un-aged material to intergranular mode for the aged one. The extent of intergranular fracture increases with the increasing aging time, indicating a tendency of the material to undergo grain boundary embrittlement over long-term aging. Analysis of the transmission electron microscopy (TEM) micrographs along with selected area diffraction (SAD) patterns for the samples aged at 10,000 hours revealed finely dispersed γ' precipitates of size 30 to 40 nm, rich in Al and Ti, along with extensive precipitation of M23C6 at the grain boundaries. In addition, the presence of Ni3Si of size in the range of 110 to 120 nm also has been noticed. The extensive precipitation of M23C6 at the grain boundaries have been considered as a major reason for aging-induced embrittlement of this material.

  13. Proximal femoral fractures.

    Science.gov (United States)

    Webb, Lawrence X

    2002-01-01

    Fractures of the proximal femur include fractures of the head, neck, intertrochanteric, and subtrochanteric regions. Head fractures commonly accompany dislocations. Neck fractures and intertrochanteric fractures occur with greatest frequency in elderly patients with a low bone mineral density and are produced by low-energy mechanisms. Subtrochanteric fractures occur in a predominantly strong cortical osseous region which is exposed to large compressive stresses. Implants used to address these fractures must be able to accommodate significant loads while the fractures consolidate. Complications secondary to these injuries produce significant morbidity and include infection, nonunion, malunion, decubitus ulcers, fat emboli, deep venous thrombosis, pulmonary embolus, pneumonia, myocardial infarction, stroke, and death.

  14. Protection of type 316 austenitic stainless steel from intergranular stress corrosion cracking by thermo-mechanical treatment

    International Nuclear Information System (INIS)

    Kiuchi, Kiyoshi; Tsuji, Hirokazu; Kondo, Tatsuo

    1980-03-01

    Thermomechanical treatment that causes carbide stabilizing aging of cold worked material followed by recrystallization heating made standard stainless steels highly resistant to intergranular corrosion and stress corrosion cracking in different test environments. After a typical thermal history of simulated welding, several IGSCC susceptibility tests were made. The results showed that the treatment was successful in type 316 steel in wide range of conditions, while type 304 was protected only to a small extent even by closely controlled treatment. Response of the materials to the sensitizing heating in terms of impurity segregation at grain boundaries was also examined by means of microchemical analysis. Advantage of method is that no special care is required in selecting heats of material, so that conventional type 316 is usable by improving the mechanical properties substantially through the treatment. In some optimized cases the mechanical property improvement was typically recognized by the yield strength by about 20% higher at room temperature, compared with the material mill annealed. (author)

  15. Influence of competition between intragranular dislocation nucleation and intergranular slip transfer on mechanical properties of ultrafine-grained metals

    International Nuclear Information System (INIS)

    Tsuru, Tomohito; Kaji, Yoshiyuki; Aoyagi, Yoshiteru; Shimokawa, Tomotsugu

    2013-01-01

    Huge-scale atomistic simulations of shear deformation tests to the aluminum polycrystalline thin film containing the Frank-Read source are performed to elucidate the relationship between the inter- and intragranular plastic deformation processes and the mechanical properties of ultrafine-grained metals. Two-types of polycrystalline models, which consist of several grain boundaries reproducing easy and hard slip transfer, respectively, are prepared to investigate the effect of grain boundary on flow stress. While the first plastic deformation occurs by the dislocation bow-out motion within the grain region for both models, the subsequent plastic deformation is strongly influenced by the resistance of the slip transfer by dislocation transmission through grain boundaries. The influence of the competition between the intragranular dislocation nucleation and intergranular slip transfer on the material strength is considered. The nanostructured material's strength depending on local defect structures associated with grain size and dislocation source length is assessed quantitatively. (author)

  16. Three-dimensional study of grain boundary engineering effects on intergranular stress corrosion cracking of 316 stainless steel in high temperature water

    Science.gov (United States)

    Liu, Tingguang; Xia, Shuang; Bai, Qin; Zhou, Bangxin; Zhang, Lefu; Lu, Yonghao; Shoji, Tetsuo

    2018-01-01

    The intergranular cracks and grain boundary (GB) network of a GB-engineered 316 stainless steel after stress corrosion cracking (SCC) test in high temperature high pressure water of reactor environment were investigated by two-dimensional and three-dimensional (3D) characterization in order to expose the mechanism that GB-engineering mitigates intergranular SCC. The 3D microstructure shown that the essential characteristic of the GB-engineered microstructure is formation of many large twin-boundaries as a result of multiple-twinning, which results in the formation of large grain-clusters. The large grain-clusters played a key role to the improvement of intergranular SCC resistance by GB-engineering. The main intergranular cracks propagated in a zigzag along the outer boundaries of these large grain-clusters because all inner boundaries of the grain-clusters were twin-boundaries (∑3) or twin-related boundaries (∑3n) which had much lower susceptibility to SCC than random boundaries. These large grain-clusters had tree-ring-shaped topology structure and very complex morphology. They got tangled so that difficult to be separated during SCC, resulting in some large crack-bridges retained in the crack surface.

  17. Effects of microstructure and local mechanical fields on intergranular stress corrosion cracking of a friction stir welded aluminum–copper–lithium 2050 nugget

    International Nuclear Information System (INIS)

    Dhondt, Matthieu; Aubert, Isabelle; Saintier, Nicolas; Olive, Jean Marc

    2014-01-01

    Highlights: • Applied stress changes the corrosion mode from pitting to intergranular cracking. • Residual stresses are sufficient to induce intergranular stress corrosion cracking. • Effect of crystallographic texture on the development of IGSCC evidenced by EBSD. • Cubic elasticity drives the local orientation of the intergranular cracking. • Tomography observations show the 3D nature of the corrosion development. - Abstract: The effects of the microstructure and mechanical fields on intergranular stress corrosion cracking (IGSCC) of the nugget zone of heat treated welds obtained by friction stir welding in the AA2050 aluminum alloy have been investigated at different scales. At low strain rate, in 1.0 NaCl aqueous solution, IGSCC develops in the microstructure, whereas only pitting corrosion is observed without any mechanical stress. Based on surface observations, EBSD analysis and X-ray tomography, the key role of sub-millimetric textured bands (induced by the welding process) on the IGSCC is demonstrated. Analyses at a more local scale show the grain boundary (low angle boundary, special coincident site lattice boundary or high angle boundary) do not have a significant effect on crack initiation. Crystal plasticity finite element calculations show that the threshold normal stress at grain boundaries for IGSCC development is about 80% of the macroscopic stress. It is also highlighted by crystal plasticity calculations that there is a drastic effect of the local stress field on the shape of cracks. Finally, it is shown that plasticity induced residual stresses are sufficient for the formation of IGSCC

  18. Evaluation of austenitic stainless steels for transpassive corrosion by metal purification technology. Synergistic effect of Si and P on intergranular corrosion of Fe-18Cr-14Ni alloys

    International Nuclear Information System (INIS)

    Mayuzumi, Masami; Ohta, Joji; Kako, Kenji; Kawakami, Eishi

    2001-01-01

    The synergistic effect of Si, Mn, C, P, and S on the transpassive corrosion of HP18Cr-14Ni alloys was studied in 13N nitric acid. The specimens were fabricated using a cold crucible method in a high-vacuum chamber to reduce contamination. The additions of Si<1% and Mn<2% had no effect on the corrosion behavior of HP18Cr-14Ni alloys, and the addition of Si<1% also had no effect on the corrosion behavior of HP18Cr-14Ni-1Mn alloys, although 1% Si induced intergranular corrosion in both the alloys. Thus, HP18Cr-14Ni-1Mn-0.5Si alloys were selected to evaluate the effects of C, P and S (100 ppm each). The addition of P, and the co-addition of C, P, and S to HP18Cr-14Ni-1Mn-0.5Si induced intergranular corrosion of the same degree in the solution annealed condition. This result suggests the synergistic effect of Si and P to induce intergranular corrosion, since the single addition of Si or P to this level did not lead to intergranular corrosion of HP18Cr-14Ni alloys. HP18Cr-14Ni-1Mn-0.5Si alloys containing C, P, and S at the 100 ppm level each showed superior corrosion resistance compared to a commercial Type 304L in 13N nitric acid. (author)

  19. Effect of boric acid on intergranular corrosion and on hideout return efficiency of sodium in the tube support plate crevices

    International Nuclear Information System (INIS)

    Paine, J.P.N.; Shoemaker, C.E.; Campan, J.L.; Brunet, J.P.; Schindler, P.; Stutzmann, A.

    1995-01-01

    Sodium hydroxide is one of the main causes of intergranular attack/stress corrosion cracking (IGA/SCC) of alloy 600 steam generator (S.G.) tubes. Boric acid appears to be one of the possible remedies for intergranular corrosion process inhibition. In order to obtain data on boric acid injection efficiency, an experimental program was performed on previously corroded tubes. To prevent premature tube wall cracking, samples were sleeved on alloy 690 tubes. The objective of the tests was to evaluate, on a statistically valid number of samples, the effectiveness of boric acid and tube sleeving as possible remedies for IGA/SCC extension. Another independent experimental program was initiated to determine the hideout return efficiency in the tube support plate (TSP) and tubesheet (TS) crevices after a significant duration (≤ 180 hours) of sodium hideout. The main objective of the first tests being a statistical evaluation of the efficiency of boric acid treatment, was not achieved. The tests did demonstrate that sleeving effectively reduces IGA/SCC growth. In an additional program, cracks were obtained on highly susceptible tubes when specimens were not sleeved. The companion tests performed in the same conditions but with an addition of boric acid did not show any IGA or cracks. These results seem to demonstrate the possible effect of boric acid in preventing the corrosion process. Results of the second tests did not demonstrate any difference in the amount of sodium piled up in the crevices before and after boric acid injection. They however showed an increase of the hideout return efficiency at the tube support plate level from 78 % without boric acid to 95 % when boric acid is present in the feed water

  20. Grain boundary segregation and intergranular stress corrosion cracking susceptibility of austenitic stainless steels in high temperature water

    International Nuclear Information System (INIS)

    Shoji, T.; Yamaki, K.; Ballinger, R.G.; Hwang, I.S.

    1992-01-01

    The effects of grain boundary segregation on intergranular stress corrosion cracking of austenitic stainless steels in high temperature water have been examined as a function of heat treatment. The materials investigated were: (1) two commercial purity Type 304; (2) low sulfur Type 304; (3) nuclear grade Type 304; (4) ultra high purity Type 304L; and (5) Type 316L and Type 347L. Specimens were solution treated at 1050 degrees C for 0.5 hour and given a sensitization heat treatment at 650 degrees C for 50 hours. Some of the specimens were then subjected to an aging heat treatment at 850 degrees C for from one to ten hours to cause Cr recovery at the grain boundaries. The effects of heat treatments on degree of sensitization and grain boundary segregation were evaluated by Electrochemical Potentiokinetic Reactivation (EPR) and Coriou tests, respectively. The susceptibility to stress corrosion (SCC) was evaluated using slow strain rate tests technique (SSRT) in high temperature water. SSRT tests were performed in an aerated pure water (8 ppm dissolved oxygen) at 288 degrees C at a strain rate of 1.33 x 10 -6 /sec. Susceptibility to intergranular stress corrosion cracking was compared with degree of sensitization and grain boundary segregation. The results of the investigation indicate that EPR is not always an accurate indicator of SCC susceptibility. The Coriou test provides a more reliable measure of SCC susceptibility especially for 304L, 304NG, 316L, and 347L stainless steels. The results also indicate that grain boundary segregation as well as degree of sensitization must be considered in the determination of SCC susceptibility

  1. Inhibition of intergranular stress corrosion cracking of sensitized type 304 stainless steel. Annual report

    International Nuclear Information System (INIS)

    Brown, B.F.

    1977-01-01

    The effectiveness of various inhibitors in mitigating stress corrosion cracking of stainless steel in hot aqueous environment was evaluated. The inhibitors studied were of three types: poly-oxy-anions, organic competitive absorbers, and simple cations; the corrosive medium was 4M NaCl acidified with H 2 SO 4 to ph of about 2.3. The following conclusions were reached: pH does not affect cracking kinetics in a sensitive way; cracking time is highly dependent on chloride concentrations; poly-oxy-anions do not perform well; organics offer some possibilities as inhibitors; cationic additives can have effects varying from trivial to total suppression of cracking--behavior is both cation and concentration dependent. 2 figures, 5 tables

  2. Fracture mechanisms of aluminium alloy AA7075-T651 under various loading conditions

    International Nuclear Information System (INIS)

    Pedersen, Ketill O.; Borvik, Tore; Hopperstad, Odd Sture

    2011-01-01

    The fracture behaviour of the aluminium alloy AA7075-T651 is investigated for quasi-static and dynamic loading conditions and different stress states. The fracture surfaces obtained in tensile tests on smooth and notched axisymmetric specimens and compression tests on cylindrical specimens are compared to the fracture surfaces that occur when a projectile, having either a blunt or an ogival nose shape, strikes a 20 mm thick plate of the aluminium alloy. The stress state in the impact tests is much more complex and the strain rate significantly higher than in the tensile and compression tests. Optical and scanning electron microscopes are used in the investigation. The fracture surface obtained in tests with smooth axisymmetric specimens indicates that the crack growth is partly intergranular along the grain boundaries or precipitation free zones and partly transgranular by void formation around fine and coarse intermetallic particles. When the stress triaxiality is increased through the introduction of a notch in the tensile specimen, delamination along the grain boundaries in the rolling plane is observed perpendicular to the primary crack. In through-thickness compression tests, the crack propagates within an intense shear band that has orientation about 45 o with respect to the load axis. The primary failure modes of the target plate during impact were adiabatic shear banding when struck by a blunt projectile and ductile hole-enlargement when struck by an ogival projectile. Delamination and fragmentation of the plates occurred for both loading cases, but was stronger for the ogival projectile. The delamination in the rolling plane was attributed to intergranular fracture caused by tensile stresses occurring during the penetration event.

  3. Traumatic thoracolumbar spine fractures

    NARCIS (Netherlands)

    J. Siebenga (Jan)

    2013-01-01

    textabstractTraumatic spinal fractures have the lowest functional outcomes and the lowest rates of return to work after injury of all major organ systems.1 This thesis will cover traumatic thoracolumbar spine fractures and not osteoporotic spine fractures because of the difference in fracture

  4. Fractures in multiple sclerosis

    DEFF Research Database (Denmark)

    Stenager, E; Jensen, K

    1991-01-01

    In a cross-sectional study of 299 MS patients 22 have had fractures and of these 17 after onset of MS. The fractures most frequently involved the femoral neck and trochanter (41%). Three patients had had more than one fracture. Only 1 patient had osteoporosis. The percentage of fractures increase...

  5. Assessment of fracture risk

    International Nuclear Information System (INIS)

    Kanis, John A.; Johansson, Helena; Oden, Anders; McCloskey, Eugene V.

    2009-01-01

    Fractures are a common complication of osteoporosis. Although osteoporosis is defined by bone mineral density at the femoral neck, other sites and validated techniques can be used for fracture prediction. Several clinical risk factors contribute to fracture risk independently of BMD. These include age, prior fragility fracture, smoking, excess alcohol, family history of hip fracture, rheumatoid arthritis and the use of oral glucocorticoids. These risk factors in conjunction with BMD can be integrated to provide estimates of fracture probability using the FRAX tool. Fracture probability rather than BMD alone can be used to fashion strategies for the assessment and treatment of osteoporosis.

  6. Local approach: fracture at high temperature in an austenitic stainless steel submitted to thermomechanical loadings. Calculations and experimental validations; Approche locale: fissuration a haute temperature dans un acier inoxydable austenitique sous chargements thermomecaniques. Simulations numeriques et validations experimentales

    Energy Technology Data Exchange (ETDEWEB)

    Poquillon, D

    1997-10-01

    Usually, for the integrity assessment of defective components, well established rules are used: global approach to fracture. A more fundamental way to deal with these problems is based on the local approach to fracture. In this study, we choose this way and we perform numerical simulations of intergranular crack initiation and intergranular crack propagation. This type of damage can be find in components of fast breeder reactors in 316 L austenitic stainless steel which operate at high temperatures. This study deals with methods coupling partly the behaviour and the damage for crack growth in specimens submitted to various thermomechanical loadings. A new numerical method based on finite element computations and a damage model relying on quantitative observations of grain boundary damage is proposed. Numerical results of crack initiation and growth are compared with a number of experimental data obtained in previous studies. Creep and creep-fatigue crack growth are studied. Various specimen geometries are considered: compact Tension Specimens and axisymmetric notched bars tested under isothermal (600 deg C) conditions and tubular structures containing a circumferential notch tested under thermal shock. Adaptative re-meshing technique and/or node release technique are used and compared. In order to broaden our knowledge on stress triaxiality effects on creep intergranular damage, new experiments are defined and conducted on sharply notched tubular specimens in torsion. These isothermal (600 deg C) Mode II creep tests reveal severe intergranular damage and creep crack initiation. Calculated damage fields at the crack tip are compared with the experimental observations. The good agreement between calculations and experimental data shows the damage criterion used can improve the accuracy of life prediction of components submitted to intergranular creep damage. (author) 200 refs.

  7. Dexamethasone suppression test

    Science.gov (United States)

    DST; ACTH suppression test; Cortisol suppression test ... During this test, you will receive dexamethasone. This is a strong man-made (synthetic) glucocorticoid medicine. Afterward, your blood is drawn ...

  8. Deconstructing continuous flash suppression

    OpenAIRE

    Yang, Eunice; Blake, Randolph

    2012-01-01

    In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in co...

  9. Paratrooper's ankle fracture: posterior malleolar fracture.

    Science.gov (United States)

    Young, Ki Won; Kim, Jin-su; Cho, Jae Ho; Kim, Hyung Seuk; Cho, Hun Ki; Lee, Kyung Tai

    2015-03-01

    We assessed the frequency and types of ankle fractures that frequently occur during parachute landings of special operation unit personnel and analyzed the causes. Fifty-six members of the special force brigade of the military who had sustained ankle fractures during parachute landings between January 2005 and April 2010 were retrospectively analyzed. The injury sites and fracture sites were identified and the fracture types were categorized by the Lauge-Hansen and Weber classifications. Follow-up surveys were performed with respect to the American Orthopedic Foot and Ankle Society ankle-hindfoot score, patient satisfaction, and return to preinjury activity. The patients were all males with a mean age of 23.6 years. There were 28 right and 28 left ankle fractures. Twenty-two patients had simple fractures and 34 patients had comminuted fractures. The average number of injury and fractures sites per person was 2.07 (116 injuries including a syndesmosis injury and a deltoid injury) and 1.75 (98 fracture sites), respectively. Twenty-three cases (41.07%) were accompanied by posterior malleolar fractures. Fifty-five patients underwent surgery; of these, 30 had plate internal fixations. Weber type A, B, and C fractures were found in 4, 38, and 14 cases, respectively. Based on the Lauge-Hansen classification, supination-external rotation injuries were found in 20 cases, supination-adduction injuries in 22 cases, pronation-external rotation injuries in 11 cases, tibiofibular fractures in 2 cases, and simple medial malleolar fractures in 2 cases. The mean follow-up period was 23.8 months, and the average follow-up American Orthopedic Foot and Ankle Society ankle-hindfoot score was 85.42. Forty-five patients (80.36%) reported excellent or good satisfaction with the outcome. Posterior malleolar fractures occurred in 41.07% of ankle fractures sustained in parachute landings. Because most of the ankle fractures in parachute injuries were compound fractures, most cases had to

  10. Evaluation by the Double Loop Electrochemical Potentiokinetic Reactivation Test of Aged Ferritic Stainless Steel Intergranular Corrosion Susceptibility

    Science.gov (United States)

    Sidhom, H.; Amadou, T.; Braham, C.

    2010-12-01

    An experimental design method was used to determine the effect of factors that significantly affect the response of the double loop-electrochemical potentiokinetic reactivation (DL-EPR) test in controlling the susceptibility to intergranular corrosion (IGC) of UNS S43000 (AISI 430) ferritic stainless steel. The test response is expressed in terms of the reactivation/activation current ratio ( I r / I a pct). Test results analysed by the analysis of variance (ANOVA) method show that the molarity of the H2SO4 electrolyte and the potential scanning rate have a more significant effect on the DL-EPR test response than the temperature and the depassivator agent concentration. On the basis of these results, a study was conducted in order to determine the optimal operating conditions of the test as a nondestructive technique for evaluating IGC resistance of ferritic stainless steel components. Three different heat treatments are considered in this study: solution annealing (nonsensitized), aging during 3 hours at 773 K (500 °C) (slightly sensitized), and aging during 2 hours at 873 K (600 °C) (highly sensitized). The aim is to find the operating conditions that simultaneously ensure the selectivity of the attack (intergranular and chromium depleted zone) and are able to detect the effect of low dechromization. It is found that a potential scanning rate of 2.5 mV/s in an electrolyte composed of H2SO4 3 M solution without depassivator, at a temperature around 293 K (20 °C), is the optimal operating condition for the DL-EPR test. Using this condition, it is possible to assess the degree of sensitization (DOS) to the IGC of products manufactured in ferritic stainless steels rapidly, reliably, and quantitatively. A time-temperature-start of sensitization (TTS) diagram for the UNS S43000 (France Inox, Villepinte, France) stainless steel was obtained with acceptable accuracy by this method when the IGC sensitization criterion was set to I r / I a > 1 pct. This diagram is in

  11. Fracture toughness of WWER Uranium dioxide fuel pellets with various grain size

    International Nuclear Information System (INIS)

    Sivov, R.; Novikov, V.; Mikheev, E.; Fedotov, A.

    2015-01-01

    Uranium dioxide fuel pellets with grain sizes 13, 26, and 33 μm for WWER were investigated in the present work in order to determine crack formation and the fracture toughness.The investigation of crack formation in uranium oxide fuel pellets of the WWER-types showed that Young’s modulus and the microhardness of polycrystalline samples increase with increasing grain size, while the fracture toughness decreases. Characteristically, radial Palmqvist cracks form on the surface of uranium dioxide pellets for loads up to 1 kg. Transgranular propagation of cracks over distances several-fold larger than the length of the imprint diagonal is observed in pellets with large grains and small intragrain pores. Intergranular propagation of cracks along grain boundaries with branching occurs in pellets with small grains and low pore concentration on the grain boundaries. Blunting on large pores and at breaks in direction does not permit the cracks to reach a significant length

  12. Young's modulus and fracture toughness of silicon nitride ceramics at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Rouxel, T. [Rennes Univ. (France). Lab. de Recherche en Mecanique Applicee

    2002-07-01

    The temperature dependencies of Young's modulus (E) and fracture toughness (K{sub 1c}) of several silicon nitride-based monolithic and composite materials, are reviewed. A transition range is observed between 1130 and 1180 C on the E(T) curves, which is systematically 150 to 200 C above the T{sub g} of oxynitride glasses of composition close to that of the intergranular glassy pockets. It is thus supposed that this transition reflects the behaviour of the interfacial glassy films. The higher the glassy phase content, the higher is the temperature sensitivity. The presence of SiC particles greatly attenuates the sensitivity. Thus, Young's modulus decreases more slowly with temperature and fracture toughness changes little up to 1300 C. The K{sub 1c} (T) curves exhibit four different stages which are discussed and interpreted on the basis of a theoretical model. (orig.)

  13. Effects of degradation on the mechanical properties and fracture toughness of a steel pressure-vessel weld metal

    International Nuclear Information System (INIS)

    Wu, S.J.; Knott, J.F.

    2003-01-01

    A degradation procedure has been devised to simulate the effect of neutron irradiation on the mechanical properties of a steel pressure-vessel weld metal. The procedure combines the application of cold prestrain together with an embrittling heat treatment to produce an increase in yield stress, a decrease in strain hardening rate, and an increased propensity for brittle intergranular fracture. Fracture tests were carried out using blunt-notch four-point-bend specimens in slow bend over a range of temperatures and the brittle/ductile transition was shown to increase by approximately 110 deg. C as a result of the degradation. Fractographic analysis of specimens broken at low temperatures showed about 30% intergranular failure in combination with transgranular cleavage. Predictions have been made of the ductile-brittle transition curves for the weld metal (sharp crack) fracture toughness in degraded and non-degraded states, based on the notched-bar test results and on finite element analyses of the stress distributions ahead of the notches and sharp cracks. The ductile-brittle transition temperature shift (ΔT=110 deg. C) between non-degraded and degraded weld metal at a notch opening displacement of 0.31 mm was combined with the Ritchie, Knott and Rice (RKR) model to predict an equivalent shift of 115 deg. C for sharp-crack specimens at a toughness level of 70 MN/m 3/2

  14. Fracture mechanical materials characterisation

    International Nuclear Information System (INIS)

    Wallin, K.; Planman, T.; Nevalainen, M.

    1998-01-01

    The experimental fracture mechanics development has been focused on the determination of reliable lower-bound fracture toughness estimates from small and miniature specimens, in particular considering the statistical aspects and loading rate effects of fracture mechanical material properties. Additionally, materials aspects in fracture assessment of surface cracks, with emphasis on the transferability of fracture toughness data to structures with surface flaws have been investigated. Further a modified crack-arrest fracture toughness test method, to increase the effectiveness of testing, has been developed. (orig.)

  15. Novel implementation of the use of the EPR-in situ technique (Electrochemical potentiodynamic reactivation) to identify intergranular corrosion susceptability of stainless steels exposed to high temperatures

    International Nuclear Information System (INIS)

    Munoz, N.; Pineda, Y.; Vera, E.; Sepulveda, H.; Heyn, Andreas

    2010-01-01

    Austenitic stainless steels (18 % Cr), are often used in pieces that are exposed to temperatures of 450 o C to 900 o C (heat exchangers). At these temperatures sensibilization occurs on the grain boundaries, becoming a key factor in the appearance of intergranular corrosion. In order to prevent this phenomena from occurring 0.3% to 0.8% of niobium is added as an alloying element in the manufacturing process, which prevents the carbon present in the steel combines with the chromium, avoiding the formation of carbides. An electrochemical method for in-situ application was developed to evaluate the corrosive behavior of stainless steel and its susceptibility and degree of sensibilizaton to an intergranular attack. This work shows the effectiveness of this technique in evaluating niobium's inhibitory effect in preventing the formation of chromium carbides on the grain boundaries of 18% chromium steel, and also shows the technique's potentiality in determining how susceptible these steels are to intercrystalline corrosion

  16. Intergranular Corrosion Behavior of 304LN Stainless Steel Heat Treated at 623 K (350 °C)

    Science.gov (United States)

    Singh, Raghuvir; Kumar, Mukesh; Ghosh, Mainak; Das, Gautam; Singh, P. K.; Chattoraj, I.

    2013-01-01

    Low temperature sensitization of 304LN stainless steel from the two pipes, differing slightly in chemical composition, has been investigated; specimens were aged at 623 K (350 °C) for 20,000 hours and evaluated for intergranular corrosion and degree of sensitization. The base and heat-affected zone (HAZ) of the 304LN-1 appear resistant to sensitization, while 304LN-2 revealed a "dual" type microstructure at the transverse section and HAZ. The microstructure at 5.0-mm distance from the fusion line indicates qualitatively less sensitization as compared to that at 2.0 mm. The 304LN-2 base alloy shows overall lower degree of sensitization values as compared to the 304LN-1. A similar trend of degree of sensitization was observed in the HAZ where it was higher in the 304LN-1 as compared to the 304LN-2. The weld zone of both the stainless steels suffered from cracking during ASTM A262 practice E, while the parent metals and HAZs did not show such fissures. A mottled image within the ferrite lamella showed spinodal decomposition. The practice E test and transmission electron microscopy results indicate that the interdendritic regions may suffer from failure due to carbide precipitation and due to the evolution of brittle phase from spinodal decomposition.

  17. Effect of water purity on intergranular stress corrosion cracking of stainless steel and nickel alloys in BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Gordon, B. [Structural Integrity Associates (United States); Garcia, S. [Electric Power Research Institute (United States)

    2011-07-01

    Boiling water reactors (BWRs) operate with very high purity water. While even the utilization of a very low conductivity water (e.g., 0.06 {mu}S/cm) coolant cannot prevent intergranular stress corrosion cracking (IGSCC) of sensitized stainless steel and nickel alloys under oxygenated conditions, the presence of certain impurities in the coolant can dramatically increase the probability of this most insidious form of corrosion. The goal of this paper is to present the effect of effect of only a few ionic impurities plus zinc on the IGSCC propensities of BWR stainless steel piping and reactor internals under both oxygenated, i.e., normal water chemistry (NWC) and deoxygenated, i.e., hydrogen water chemistry (HWC) conditions. More specifically, of the numerous impurities identified in the BWR coolant (e.g., lithium, sodium, potassium, silica, borate, chromate, phosphate, sulphate, chloride, nitrate, cuprous, cupric, ferrous, etc.) only strong acid anions sulfate and chloride that are stable in the highly reducing crack tip environment rather than the bulk water conductivity will be discussed in detail. Nitrate will be briefly discussed as representing a species that is not thermodynamically stable in the crack while the effects of zinc is discussed as a deliberate additive to the BWR environment. (authors)

  18. Intergranular corrosion behavior associated with delta-ferrite transformation of Ti-modified Super304H austenitic stainless steel

    International Nuclear Information System (INIS)

    Bai, Guanshun; Lu, Shanping; Li, Dianzhong; Li, Yiyi

    2015-01-01

    Highlights: • Relationship between delta-ferrite transformation and IGC behavior was evaluated by DL-EPR test quantitatively. • The IGC site at austenite/ferrite grain boundary changes with aging time at 650 °C. • A higher fraction of delta-ferrite with poor stability increases the IGC sensitisation. • Self-healing of IGC was mainly induced by the Cr diffusion from primary austenite rather than the delta-ferrite. - Abstract: A double loop electrochemical potentiokinetic reactivation (DL-EPR) test was conducted to investigate the relationship between the evolution of delta-ferrite and the intergranular corrosion (IGC) of Ti-modified Super304H, which was aged at 650 °C for 4–500 h. Scanning electron microscopy and transmission electron microscopy were adopted to analyze the evolution of delta-ferrite. The results indicated that a higher fraction of delta-ferrite with poor stability increased the IGC sensitisation of Ti-modified Super304H. Moreover, the self-healing of the sensitisation of Ti-modified Super304H occurred after 48 h due to the diffusion of chromium atoms mainly from the adjacent primary austenite rather than the delta-ferrite

  19. Effect of hot extrusion, other constituents, and temperature on the strength and fracture of polycrystalline MgO

    Energy Technology Data Exchange (ETDEWEB)

    Rice, R.W. (W.R. Grace and Co.-Conn, Columbia, MD (United States))

    1993-12-01

    Improved agreement was confirmed between the Petch intercept and single-crystal yield stresses at 22 C. Hot-extruded MgO crystal specimens stressed parallel with the resultant axial texture (1) gave the highest and least-scattered strength-grain size results at 22 C, (2) showed direct fractographic evidence of microplastic initiated fracture at 22 C and showed macroscopic yield at 1,315 and especially 1,540 C, and (3) fractured entirely via transgranular cleavage, except for intergranular failure initiation from one or a few grain boundary surfaces exposed on the subsequent fracture surface, mainly at 1,540 C. Hot-extruded, hot-pressed MgO billets gave comparable strength when fracture initiated transgranularly, but lower strength when fracture initiated from one or especially a few grain boundary surfaces exposed on the fracture. The extent and frequency of such boundary fracture increased with test temperature. While oxide additions of [<=] 5% or impurities in hot-pressed or hot-extruded MgO can make limited strength increases at larger grain sizes, those having limited solubility can limit strength at finer grain sizes, as can coarser surface finish. Overall, MgO strength is seen as a balance between flaw and microplastic controlled failure, with several parameters shifting the balance.

  20. Slip, twinning, and fracture at a grain boundary in the L1/sub 2/ ordered structure: A. sigma. = 9 tilt boundary

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, M.H.; King, A.H.

    1988-09-01

    The role of interaction between slip dislocations and a ..sigma.. = 9 tilt boundary in localized microplastic deformation, cleavage, or intergranular fracture in the L1/sub 2/ ordered structure has been analyzed by using the anisotropic elasticity theory of dislocations and fracture. Screw superpartials cross slip easily at the boundary onto the (11-bar1) and the (001) planes at low and high temperatures, respectively. Transmission of primary slip dislocations onto the conjugate slip system occurs with a certain degree of difficulty, which is eased by localized disordering. When the transmission is impeded, cleavage fracture on the (1-bar11) plane is predicted to occur, not intergranular fracture, unless a symmetric double pileup occurs simultaneously. Absorption (or emission) of superpartials occurs only when the boundary region is disordered. Slip initiation from pre-existing sources near the boundary can occur under the local stress concentration. Implications of the present result on the inherent brittleness of grain boundaries in Ni/sub 3/ Al and its improvement by boron segregation are discussed.

  1. Fracture-toughness variations in Alloy 718

    International Nuclear Information System (INIS)

    Mills, W.J.; Blackburn, L.D.

    1983-04-01

    The effect of product-form variations within a single heat on the J Ic fracture toughness behavior of Alloy 718 was examined at 24, 427 and 538 degree C using the multiple-specimen J R -curve method. Three product forms (plate, round bar and upset forging) were tested in both the conventional and modified heat-treatment (CHT and MHT) conditions. In CHT material, the fracture toughness response was different for the three product forms -- plate having the highest toughness, bar the lowest. The MHT was found to improve the overall fracture resistance for each product form. In this condition, plate and forging had very similar toughness values, but J Ic levels for the bar were considerably lower. These results and WHC data previously reported for four other Alloy 718 heats were unalloyed statistically to establish minimum-expected J Ic values based on tolerance limits bracketing 90% of a total population at a 95% confidence level. Metallographic and fractographic examinations of the seven material lots were performed to relate key microstructural features and operative fracture mechanisms to macroscopic properties. Generally, coarse δ precipitates controlled fracture properties in CHT material by initiating secondary dimples that pre-empted growth of the primary dimples nucleated by broken carbide inclusions. The MHT dissolved the coarse δ particles and thereby suppressed secondary microvoid coalescence. This generally enhanced the fracture resistance of Alloy 718, except when alternate secondary fracture mechanism, such as channel fracture and dimple rupture at δ-phase remnants, prematurely interrupted primary microvoid growth. 25 refs., 12 figs., 12 tabs

  2. An Abrupt Transition to an Intergranular Failure Mode in the Near-Threshold Fatigue Crack Growth Regime in Ni-Based Superalloys

    Science.gov (United States)

    Telesman, J.; Smith, T. M.; Gabb, T. P.; Ring, A. J.

    2018-06-01

    Cyclic near-threshold fatigue crack growth (FCG) behavior of two disk superalloys was evaluated and was shown to exhibit an unexpected sudden failure mode transition from a mostly transgranular failure mode at higher stress intensity factor ranges to an almost completely intergranular failure mode in the threshold regime. The change in failure modes was associated with a crossover of FCG resistance curves in which the conditions that produced higher FCG rates in the Paris regime resulted in lower FCG rates and increased ΔK th values in the threshold region. High-resolution scanning and transmission electron microscopy were used to carefully characterize the crack tips at these near-threshold conditions. Formation of stable Al-oxide followed by Cr-oxide and Ti-oxides was found to occur at the crack tip prior to formation of unstable oxides. To contrast with the threshold failure mode regime, a quantitative assessment of the role that the intergranular failure mode has on cyclic FCG behavior in the Paris regime was also performed. It was demonstrated that even a very limited intergranular failure content dominates the FCG response under mixed mode failure conditions.

  3. Fractures (Broken Bones): First Aid

    Science.gov (United States)

    First aid Fractures (broken bones) Fractures (broken bones): First aid By Mayo Clinic Staff A fracture is a ... 10, 2018 Original article: http://www.mayoclinic.org/first-aid/first-aid-fractures/basics/ART-20056641 . Mayo Clinic ...

  4. Effect of Y2O3-Al2O3 ratio on inter-granular phases and films in tape-casting α-SiC with high toughness

    International Nuclear Information System (INIS)

    Huang Rong; Gu Hui; Zhang Jingxian; Jiang Dongliang

    2005-01-01

    Silicon carbide (SiC) ceramics prepared from liquid phase sintering after aqueous-tape-casting can yield high toughness when appropriate amount of Y 2 O 3 -Al 2 O 3 are added, even though no elongated grains are present. Grain boundaries (GB), second-phases and hetero-phase boundaries (HB) in 2 samples with additive mole ratios of 3:5 and 3:7 are investigated using high-resolution and analytical electron microscopy (HREM and AEM). The meta-stable YAlO 3 (YAP) was nucleated from SiC surfaces in the sample with Y/Al = 3:5 as revealed by crystallographic relations across the HB, whilst relatively thick amorphous films were found at GB. In contrary, the higher level of Al 2 O 3 additives decreases the GB film thickness in the sample with Y/Al = 3:7, and the homogeneous nucleation of Y 3 Al 5 O 12 (YAG) occurs at triple pockets accompanying with thick HB films. The strong variation of GB widths is a result of GB wetting in the sample with Y/Al = 3:5 and HB wetting in the sample of Y/Al = 3:7, both by liquid Al 2 O 3 . The energy of GB in the former sample is higher than the energy of HB as exhibited by the preferential nucleation of meta-stable YAP on SiC surfaces, which results in wetting of GB by the liquid; the situation is opposite in the latter sample as the wetting of HB occurs, leading to de-wetting of GB. The thermal mismatch between SiC and YAP or YAG as well as the presence of amorphous films facilitate the creation of micro-crack to promote inter-granular fracture and result in high toughness in both SiC ceramics

  5. Fracture toughness correlations

    International Nuclear Information System (INIS)

    Wallin, Kim

    1986-09-01

    In this study existing fracture parameter correlations are reviewed. Their applicability and reliability are discussed in detail. A new K IC -CVN-correlation, based on a theoretical brittle fracture model, is presented

  6. Rib fracture - aftercare

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000539.htm Rib fracture - aftercare To use the sharing features on this page, please enable JavaScript. A rib fracture is a crack or break in one or ...

  7. Sprains, Strains and Fractures

    Science.gov (United States)

    ... fractures. Many fractures and sprains occur during sports. Football players are particularly vulnerable to foot and ankle ... feet and ankles and take a complete medical history. He or she will also order tests, including ...

  8. Infant skull fracture (image)

    Science.gov (United States)

    Skull fractures may occur with head injuries. Although the skull is both tough and resilient and provides excellent ... or blow can result in fracture of the skull and may be accompanied by injury to the ...

  9. Ankle fracture - aftercare

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000548.htm Ankle fracture - aftercare To use the sharing features on this page, please enable JavaScript. An ankle fracture is a break in 1 or more ankle ...

  10. Influence of irradiation on microyielding and fracture of polycrystalline MgO

    International Nuclear Information System (INIS)

    Ibrahim, N.A.; Tangri, K.

    1976-01-01

    Detailed study of the microstructural features characterizing microyielding and fracture in polycrystalline MgO is reported for the material in irradiated and unirradiated conditions. In both materials fracture is preceded by plastic flow, and intergranular cracks are initiated by slip bands encountering unfavourably oriented grains. The data provide direct evidence for three irreversible energy dissipating processes associated with fracture. These are: generation of plastic zones; formation of secondary cracks; and creation of discrete microcracks. Irradiation is found to produce two competing effects; it it increases the stress required to initiate fracture and decreases the irreversible energy expenditure during crack extension. A linear relationship between fracture stress and (grain diameter)sup(-1/2) is found for the irradiated material but a non-linear behaviour is observed for the unirradiated material. The behaviour in the unirradiated material is explained in terms of dependence off γsub(irr) (excess surface energy due to various irreversible energy dissipating processes) on grain size. (author)

  11. Relationship between microstructure and fracture types in a UNS S32205 duplex stainless steel

    Directory of Open Access Journals (Sweden)

    Maria Victoria Biezma

    2013-01-01

    Full Text Available Duplex stainless steels are susceptible to the formation of sigma phase at high temperature which could potentially be responsible for catastrophic service failure of components. Thermal treatments were applied to duplex stainless steels in order to promote the precipitation of different fractions of sigma phase into a ferrite-austenite microstructure. Quantitative image analysis was employed to characterize the microstructure and Charpy impact tests were used in order to evaluate the mechanical degradation caused by sigma phase presence. The fracture morphology of the Charpy test specimens were thoroughly observed in SEM, looking for a correlation between the microstructure and the fracture types in UNS S32205 duplex stainless steel. The main conclusion is the strong embrittlement effect of sigma phase since it is possible to observe a transition from transgranular fracture to intergranular fracture as increases the percentage of sigma phase. Thus, the mixed modes of fracture are predominant in the present study with high dependence on sigma phase percentages obtained by different thermal treatments.

  12. Atraumatic First Rib Fracture

    OpenAIRE

    Koray Aydogdu

    2014-01-01

    Rib fractures are usually seen after a trauma, while atraumatic spontaneous rib fractures are quite rare. A first rib fracture identified in our 17 years old female patient who had not a history of trauma except lifting a heavy weight was examined in details in terms of the potential complications and followed-up for a long time. We presented our experience on this case with atraumatic first rib fracture that has different views for the etiology in light of the literature.

  13. Deconstructing continuous flash suppression.

    Science.gov (United States)

    Yang, Eunice; Blake, Randolph

    2012-03-08

    In this paper, we asked to what extent the depth of interocular suppression engendered by continuous flash suppression (CFS) varies depending on spatiotemporal properties of the suppressed stimulus and CFS suppressor. An answer to this question could have implications for interpreting the results in which CFS influences the processing of different categories of stimuli to different extents. In a series of experiments, we measured the selectivity and depth of suppression (i.e., elevation in contrast detection thresholds) as a function of the visual features of the stimulus being suppressed and the stimulus evoking suppression, namely, the popular "Mondrian" CFS stimulus (N. Tsuchiya & C. Koch, 2005). First, we found that CFS differentially suppresses the spatial components of the suppressed stimulus: Observers' sensitivity for stimuli of relatively low spatial frequency or cardinally oriented features was more strongly impaired in comparison to high spatial frequency or obliquely oriented stimuli. Second, we discovered that this feature-selective bias primarily arises from the spatiotemporal structure of the CFS stimulus, particularly within information residing in the low spatial frequency range and within the smooth rather than abrupt luminance changes over time. These results imply that this CFS stimulus operates by selectively attenuating certain classes of low-level signals while leaving others to be potentially encoded during suppression. These findings underscore the importance of considering the contribution of low-level features in stimulus-driven effects that are reported under CFS.

  14. Metatarsal stress fractures - aftercare

    Science.gov (United States)

    ... Metatarsal stress fracture. In: Safran MR, Zachazewski J, Stone DA, eds. Instructions for Sports Medicine Patients . 2nd ed. Elsevier Saunders; 2012:648-652. Smith MS. Metatarsal fractures. In: Eiff PM, Hatch R, eds. Fracture Management for Primary Care . 3rd ed. ...

  15. Relationships between fractures

    Science.gov (United States)

    Peacock, D. C. P.; Sanderson, D. J.; Rotevatn, A.

    2018-01-01

    Fracture systems comprise many fractures that may be grouped into sets based on their orientation, type and relative age. The fractures are often arranged in a network that involves fracture branches that interact with one another. Interacting fractures are termed geometrically coupled when they share an intersection line and/or kinematically coupled when the displacements, stresses and strains of one fracture influences those of the other. Fracture interactions are characterised in terms of the following. 1) Fracture type: for example, whether they have opening (e.g., joints, veins, dykes), closing (stylolites, compaction bands), shearing (e.g., faults, deformation bands) or mixed-mode displacements. 2) Geometry (e.g., relative orientations) and topology (the arrangement of the fractures, including their connectivity). 3) Chronology: the relative ages of the fractures. 4) Kinematics: the displacement distributions of the interacting fractures. It is also suggested that interaction can be characterised in terms of mechanics, e.g., the effects of the interaction on the stress field. It is insufficient to describe only the components of a fracture network, with fuller understanding coming from determining the interactions between the different components of the network.

  16. Obesity and fracture risk

    OpenAIRE

    Gonnelli, Stefano; Caffarelli, Carla; Nuti, Ranuccio

    2014-01-01

    Obesity and osteoporosis are two common diseases with an increasing prevalence and a high impact on morbidity and mortality. Obese women have always been considered protected against osteoporosis and osteoporotic fractures. However, several recent studies have challenged the widespread belief that obesity is protective against fracture and have suggested that obesity is a risk factor for certain fractures.

  17. Imaging of insufficiency fractures

    Energy Technology Data Exchange (ETDEWEB)

    Krestan, Christian [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)], E-mail: christian.krestan@meduniwien.ac.at; Hojreh, Azadeh [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)

    2009-09-15

    This review focuses on the occurrence, imaging and differential diagnosis of insufficiency fractures. Prevalence, the most common sites of insufficiency fractures and their clinical implications are discussed. Insufficiency fractures occur with normal stress exerted on weakened bone. Postmenopausal osteoporosis is the most common cause of insufficiency fractures. Other conditions which affect bone turnover include osteomalacia, hyperparathyroidism, chronic renal failure and high-dose glucocorticoid therapy. It is a challenge for the radiologist to detect and diagnose insufficiency fractures, and to differentiate them from other bone lesions. Radiographs are still the most widely used imaging method for identification of insufficiency fractures, but sensitivity is limited, depending on the location of the fractures. Magnetic resonance imaging (MRI) is a very sensitive tool to visualize bone marrow abnormalities associated with insufficiency fractures. Thin section, multi-detector computed tomography (MDCT) depicts subtle fracture lines allowing direct visualization of cortical and trabecular bone. Bone scintigraphy still plays a role in detecting fractures, with good sensitivity but limited specificity. The most important differential diagnosis is underlying malignant disease leading to pathologic fractures. Bone densitometry and clinical history may also be helpful in confirming the diagnosis of insufficiency fractures.

  18. Effect of Random Natural Fractures on Hydraulic Fracture Propagation Geometry in Fractured Carbonate Rocks

    Science.gov (United States)

    Liu, Zhiyuan; Wang, Shijie; Zhao, Haiyang; Wang, Lei; Li, Wei; Geng, Yudi; Tao, Shan; Zhang, Guangqing; Chen, Mian

    2018-02-01

    Natural fractures have a significant influence on the propagation geometry of hydraulic fractures in fractured reservoirs. True triaxial volumetric fracturing experiments, in which random natural fractures are created by placing cement blocks of different dimensions in a cuboid mold and filling the mold with additional cement to create the final test specimen, were used to study the factors that influence the hydraulic fracture propagation geometry. These factors include the presence of natural fractures around the wellbore, the dimension and volumetric density of random natural fractures and the horizontal differential stress. The results show that volumetric fractures preferentially formed when natural fractures occurred around the wellbore, the natural fractures are medium to long and have a volumetric density of 6-9%, and the stress difference is less than 11 MPa. The volumetric fracture geometries are mainly major multi-branch fractures with fracture networks or major multi-branch fractures (2-4 fractures). The angles between the major fractures and the maximum horizontal in situ stress are 30°-45°, and fracture networks are located at the intersections of major multi-branch fractures. Short natural fractures rarely led to the formation of fracture networks. Thus, the interaction between hydraulic fractures and short natural fractures has little engineering significance. The conclusions are important for field applications and for gaining a deeper understanding of the formation process of volumetric fractures.

  19. Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures

    International Nuclear Information System (INIS)

    Nachtrab, O.; Cassar-Pullicino, V.N.; Lalam, R.; Tins, B.; Tyrrell, P.N.M.; Singh, J.

    2012-01-01

    MR imaging plays a vital role in the diagnosis and management of hip fractures in all age groups, in a large spectrum of patient groups spanning the elderly and sporting population. It allows a confident exclusion of fracture, differentiation of bony from soft tissue injury and an early confident detection of fractures. There is a spectrum of MR findings which in part is dictated by the type and cause of the fracture which the radiologist needs to be familiar with. Judicious but prompt utilisation of MR in patients with suspected hip fractures has a positive therapeutic impact with healthcare cost benefits as well as social care benefits.

  20. Improvement of hydrogen sorption properties of compounds based on Vanadium “bcc” alloys by mean of intergranular phase development

    International Nuclear Information System (INIS)

    Planté, D.; Raufast, C.; Miraglia, S.; Rango, P. de; Fruchart, D.

    2013-01-01

    Highlights: •Decrease of “bcc” pseudo cell with the increase of amount of additive. •Additive phase improve activation kinetics. •Chromium in the “bcc” matrix decreases the lattice parameter and destabilizes hydride formation/dissociation. •Lower working temperatures could be obtain. -- Abstract: Body centered cubic structure (“bcc”) type alloys based on Vanadium [1] reveal promising characteristics for mobile applications. These disordered solid solutions have particular metal/hydride equilibrium and some regulation aspects have leaded us to pay special attention to this type of material [2]. Compounds based on Vanadium-rich solid solution have been elaborated in order to destabilize γ hydride phase (corresponding to the face centered cubic (“fcc”) structure of VH 2 ). Addition of Ni and Zr-rich Laves phase as a secondary phase results in the development of a particular microstructure composed of a principal “bcc” matrix rounded by intergranular activating phase. This results in a facilitated and faster activation of these compounds. The present study shows that some constituting species of the secondary phase have diffused in the main matrix and therefore have modified the thermodynamic of hydride. In fact, chromium diffusion into the “bcc” matrix destabilizes hydride. It is correlated to the lower stability of chromium hydride compared to Vanadium hydride. The enthalpic terms of each sample have been measured (assuming standard entropy of 130 J mol −1 K −1 ). The equilibrium metal/hydride can be easily switched in order to adapt it to a mobile hydride tank and obtain low working temperature in regard to the potential use

  1. The role of time-dependent deformation in intergranular crack initiation of alloy 600 steam generator tubing material

    International Nuclear Information System (INIS)

    Was, G.S.; Lian, K.

    1998-03-01

    Intergranular stress corrosion cracking (IGSCC) of two commercial alloy 600 conditions (600LT, 600HT) and controlled- purity Ni-18Cr-9Fe alloys (CDMA, CDTT) were investigated using constant extension rate tensile (CERT) tests in primary water (0.01M LiOH+0.01M H 3 BO 3 ) with 1 bar hydrogen overpressure at 360 degrees C and 320 degrees C. Heat treatments produced two types of microstructures in both commercial and controlled-purity alloys: one dominated by grain boundary carbides (600HT and CDTT) and one dominated by intragranular carbides (600LT and CDMA). CERT tests were conducted over a range of strain rates and at two temperatures with interruptions at specific strains to determine the crack depth distributions. Results show that in all samples, IGSCC was the dominant failure mode. For both the commercial alloy and the controlled-purity alloys, the microstructure with grain boundary carbides showed delayed crack initiation and shallower crack depths than did the intragranular carbide microstructure under all experimental conditions. This data indicates that a grain boundary carbide microstructure is more resistant to IGSCC than an intragranular carbide microstructure. Observations support both the film rupture/slip dissolution mechanism and enhanced localized plasticity. The advantage of these results over previous studies is that the different carbide distributions were obtained in the same commercial alloy using different heat treatments, and in the other case, in nearly identical controlled-purity alloys. Therefore, observations of the effects of carbide distribution on IGSCC can more confidently be attributed to the carbide distribution alone rather than other potentially significant differences in microstructure or composition

  2. Assessment of susceptibility of Type 304 stainless steel to intergranular stress corrosion cracking in simulated Savannah River Reactor environments

    International Nuclear Information System (INIS)

    Ondrejcin, R.S.; Caskey, C.R. Jr.

    1989-01-01

    Intergranular stress corrosion cracking (IGSCC) of Type 304 stainless steel rate tests (CERT) of specimens machined was evaluated by constant extension from Savannah River Plant (SRP) decontaminated process water piping. Results from 12 preliminary CERT tests verified that IGSCC occurred over a wide range of simulated SRP envirorments. 73 specimens were tested in two statistical experimental designs of the central composite class. In one design, testing was done in environments containing hydrogen peroxide; in the other design, hydrogen peroxide was omitted but oxygen was added to the environment. Prediction equations relating IGSCC to temperature and environmental variables were formulated. Temperature was the most important independent variable. IGSCC was severe at 100 to 120C and a threshold temperature between 40C and 55C was identified below which IGSCC did not occur. In environments containing hydrogen peroxide, as in SRP operation, a reduction in chloride concentration from 30 to 2 ppB also significantly reduced IGSCC. Reduction in sulfate concentration from 50 to 7 ppB was effective in reducing IGSCC provided the chloride concentration was 30 ppB or less and temperature was 95C or higher. Presence of hydrogen peroxide in the environment increased IGSCC except when chloride concentration was 11 ppB or less. Actual concentrations of hydrogen peroxide, oxygen and carbon dioxide did not affect IGSCC. Large positive ECP values (+450 to +750 mV Standard Hydrogen Electrode (SHE)) in simulated SRP environments containing hydrogen peroxide and were good agreement with ECP measurements made in SRP reactors, indicating that the simulated environments are representative of SRP reactor environments. Overall CERT results suggest that the most effective method to reduce IGSCC is to reduce chloride and sulfate concentrations

  3. A comparing study of alloy 600 and alloy 690 on resistance to intergranular stress corrosion cracking(IGSCC)

    International Nuclear Information System (INIS)

    Lee, Jae Hun

    1993-02-01

    In order to compare the effect of senitization on the intergranular stress corrosion cracking(IGSCC) between Alloy 600 and Alloy 690, these alloys have been sensitized for 1 to 100 hours at 700 .deg. C. The degree of sensitization(DOS) has evaluated by the ratio of Ir(the maximum current density at anodic scan) to Ia(the maximum current density at reverse scan) in the modified double loop EPR(electrochemical potentiokinetic reactivation) test in 0.01M H 2 SO 4 + 0.0001M KSCN at 25 .deg. C and at scan rate of 0.5mV/sec. The susceptibility to IGSCC has been measured in 0.01M Na 2 S 4 O 6 solution using CERT(constant extension rate tester) at strain rate of 1.0 x 10 -6 S -1 . With increasing sensitization time the DOS of Alloy 600 increases to the maximum value at 5 hours and decreases gradually due to the replenishment of Cr to the Cr-depleted grain boundaries. For Alloy 600 samples except those sensitized for less than 1 hour, the DOS measured by the modified EPR test parallel to susceptibility to IGSCC revealed by the ratio of strain to failure (εf, Na 2 S 4 O 6 /εf, Air). It appears that the susceptibility to IGSCC is closely associated with the depth in Cr-depleted concentration profile across grain boundary. For the sensitized Alloy 690 samples exhibited extremely low value of Ir/Ia less than 0.074% and also were immune to IGSCC. The good resistance of Alloy 690 to IGSCC is considered to be attributed to the higher Cr concentration to avoid serious Cr-depletion problems adjacent to grain boundary

  4. Intergranular tellurium cracking of nickel-based alloys in molten Li, Be, Th, U/F salt mixture

    Science.gov (United States)

    Ignatiev, Victor; Surenkov, Alexander; Gnidoy, Ivan; Kulakov, Alexander; Uglov, Vadim; Vasiliev, Alexander; Presniakov, Mikhail

    2013-09-01

    In Russia, R&D on Molten Salt Reactor (MSR) are concentrated now on fast/intermediate spectrum concepts which were recognized as long term alternative to solid fueled fast reactors due to their attractive features: strong negative feedback coefficients, easy in-service inspection, and simplified fuel cycle. For high-temperature MSR corrosion of the metallic container alloy in primary circuit is the primary concern. Key problem receiving current attention include surface fissures in Ni-based alloys probably arising from fission product tellurium attack. This paper summarizes results of corrosion tests conducted recently to study effect of oxidation state in selected fuel salt on tellurium attack and to develop means of controlling tellurium cracking in the special Ni-based alloys recently developed for molten salt actinide recycler and tranforming (MOSART) system. Tellurium corrosion of Ni-based alloys was tested at temperatures up to 750 °C in stressed and unloaded conditions in molten LiF-BeF2 salt mixture fueled by about 20 mol% of ThF4 and 2 mol% of UF4 at different [U(IV)]/[U(III)] ratios: 0.7, 4, 20, 100 and 500. Following Ni-based alloys (in mass%): HN80М-VI (Mo—12, Cr—7.6, Nb—1.5), HN80МТY (Mo—13, Cr—6.8, Al—1.1, Ti—0.9), HN80МТW (Mo—9.4, Cr—7.0, Ti—1.7, W—5.5) and ЕМ-721 (W—25.2, Cr—5.7, Ti—0.17) were used for the study in the corrosion facility. If the redox state the fuel salt is characterized by uranium ratio [U(IV)]/[U(III)] uranium intermetallic compounds and alloys with nickel and molybdenum. This leads to spontaneous behavior of alloy formation processes on the specimens' surface and further diffusion of uranium deep into the metallic phase. As consequence of this films of intermetallic compounds and alloys of nickel, molybdenum, tungsten with uranium are formed on the alloys specimens' surface, and intergranular corrosion does not take place. In the fuel salt with [U(IV)]/[U(III)] = 4-20 the potentials of uranium

  5. Fracture behavior of nickel-based alloys in water

    Energy Technology Data Exchange (ETDEWEB)

    Mills, W.J.; Brown, C.M.

    1999-08-01

    The cracking resistance of Alloy 600, Alloy 690 and their welds, EN82H and EN52, was characterized by conducting J{sub IC} tests in air and hydrogenated water. All test materials displayed excellent toughness in air and high temperature water, but Alloy 690 and the two welds were severely embrittled in low temperature water. In 54 C water with 150 cc H{sub 2}/kg H{sub 2}O, J{sub IC} values were typically 70% to 95% lower than their air counterparts. The toughness degradation was associated with a fracture mechanism transition from microvoid coalescence to intergranular fracture. Comparison of the cracking response in water with that for hydrogen-precharged specimens tested in air demonstrated that susceptibility to low temperature cracking is due to hydrogen embrittlement of grain boundaries. The effects of water temperature, hydrogen content and loading rate on low temperature crack propagation were studied. In addition, testing of specimens containing natural weld defects and as-machined notches was performed to determine if low temperature cracking can initiate at these features. Unlike the other materials, Alloy 600 is not susceptible to low temperature cracking as the toughness in 54 C water remained high and a microvoid coalescence mechanism was operative in both air and water.

  6. Orbital fractures: a review

    Directory of Open Access Journals (Sweden)

    Jeffrey M Joseph

    2011-01-01

    Full Text Available Jeffrey M Joseph, Ioannis P GlavasDivision of Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, School of Medicine, New York University, New York, NY, USA; Manhattan Eye, Ear, and Throat Hospital, New York, NY, USAAbstract: This review of orbital fractures has three goals: 1 to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2 to explain how to assess and examine a patient after periorbital trauma, and 3 to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training.Keywords: orbit, trauma, fracture, orbital floor, medial wall, zygomatic, zygomatic complex, zmc fracture, zygomaticomaxillary complex fractures 

  7. Mechanics of Hydraulic Fractures

    Science.gov (United States)

    Detournay, Emmanuel

    2016-01-01

    Hydraulic fractures represent a particular class of tensile fractures that propagate in solid media under pre-existing compressive stresses as a result of internal pressurization by an injected viscous fluid. The main application of engineered hydraulic fractures is the stimulation of oil and gas wells to increase production. Several physical processes affect the propagation of these fractures, including the flow of viscous fluid, creation of solid surfaces, and leak-off of fracturing fluid. The interplay and the competition between these processes lead to multiple length scales and timescales in the system, which reveal the shifting influence of the far-field stress, viscous dissipation, fracture energy, and leak-off as the fracture propagates.

  8. Ballistic fractures: indirect fracture to bone.

    Science.gov (United States)

    Dougherty, Paul J; Sherman, Don; Dau, Nathan; Bir, Cynthia

    2011-11-01

    Two mechanisms of injury, the temporary cavity and the sonic wave, have been proposed to produce indirect fractures as a projectile passes nearby in tissue. The purpose of this study is to evaluate the temporal relationship of pressure waves using strain gauge technology and high-speed video to elucidate whether the sonic wave, the temporary cavity, or both are responsible for the formation of indirect fractures. Twenty-eight fresh frozen cadaveric diaphyseal tibia (2) and femurs (26) were implanted into ordnance gelatin blocks. Shots were fired using 9- and 5.56-mm bullets traversing through the gelatin only, passing close to the edge of the bone, but not touching, to produce an indirect fracture. High-speed video of the impact event was collected at 20,000 frames/s. Acquisition of the strain data were synchronized with the video at 20,000 Hz. The exact time of fracture was determined by analyzing and comparing the strain gauge output and video. Twenty-eight shots were fired, 2 with 9-mm bullets and 26 with 5.56-mm bullets. Eight indirect fractures that occurred were of a simple (oblique or wedge) pattern. Comparison of the average distance of the projectile from the bone was 9.68 mm (range, 3-20 mm) for fractured specimens and 15.15 mm (range, 7-28 mm) for nonfractured specimens (Student's t test, p = 0.036). In this study, indirect fractures were produced after passage of the projectile. Thus, the temporary cavity, not the sonic wave, was responsible for the indirect fractures.

  9. Aging effects on fracture behavior of 63Sn37Pb eutectic solder during tensile tests under the SEM

    International Nuclear Information System (INIS)

    Ding Ying; Wang Chunqing; Li Mingyu; Bang Hansur

    2004-01-01

    This study investigates the influence of aging treatment on fracture behavior of Sn-Pb eutectic solder alloys at different loading rate regime during tensile tests under the scanning electron microscope. In high homologous temperature, the solder exhibit the creep behavior that could be confirmed through the phenomena of grain boundary sliding (GBS) to both as-cast and aged specimens. Owing to the large grain scale after high temperature storage, boundary behavior was limited to some extent for the difficulty in grain rotation and boundary migration. Instead, drastic intragranular deformation occurred. Also, the phase coarsening weakened the combination between lead-rich phase and tin matrix. Consequently, surface fragmentation was detected for the aged specimens. Furthermore, the fracture mechanism changed from intergranular dominated to transgranular dominated with increasing loading rate to both specimens during early stage

  10. Quantitative tomography of hydrogen precharged and uncharged Al-Zn-Mg-Cu alloy after tensile fracture

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, C., E-mail: joy_gupta71@yahoo.co.in [Department of Mechanical Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8150 (Japan); Toda, H.; Fujioka, T.; Kobayashi, M. [Department of Mechanical Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8150 (Japan); Hoshino, H. [Department of Mechanical Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8150 (Japan); Japan Synchrotron Radiation Institute, Sayo-Gun, Hyogo (Japan); Uesugi, K.; Takeuchi, A.; Suzuki, Y. [Japan Synchrotron Radiation Institute, Sayo-Gun, Hyogo (Japan)

    2016-07-18

    Quantitative tomography is carried out on datasets derived from tensile fracture sample of electrochemically precharged Al-Zn-Mg-Cu alloy in the underaged condition and its uncharged counterpart. It is shown that precharging which induces a transition of tensile fracture mode from ductile to brittle, results in a significant increase in micro-damage content in the regions near the fracture surfaces. Using quantitative tomography analysis based on spatial mapping of morphologically segmented micro-damage content of the datasets it is found that the precharged sample contains an inhomogenous distribution of micro-pores near grain boundaries. It is also shown that the spatial architecture of micro-pores in the dataset is not influenced by the plastic zone of the intergranular cracks lying along the grain boundaries. Contrastingly the micro-pores in the tomographic dataset of the uncharged sample are shown to be present near intermetallic particles. It is therefore rationalized that the spatial architecture of micro-pores in the datasets from uncharged sample originate from particle cracking during ductile fracture, and from the tendency for damage enhancement by the synergism of hydrogen exposure near grain boundaries and localization of deformation in the precharged sample dataset.

  11. Effect of He implantation on fracture behavior and microstructural evolution in F82H

    Energy Technology Data Exchange (ETDEWEB)

    Yabuuchi, Kiyohiro, E-mail: kiyohiro.yabuuchi@qse.tohoku.ac.jp [Department of Quantum Science and Energy Engineering, Tohoku University, 6-6-01-2, Aramaki-Aza-Aoba, Aobaku, Sendai, Miyagi 980-8579 (Japan); Sato, Kiminori; Nogami, Shuhei; Hasegawa, Akira [Department of Quantum Science and Energy Engineering, Tohoku University, 6-6-01-2, Aramaki-Aza-Aoba, Aobaku, Sendai, Miyagi 980-8579 (Japan); Ando, Masami; Tanigawa, Hiroyasu [Japan Atomic Energy Agency, 2-166, Oaza-Obuchi-Aza-Omotedate, Rokkasho-mura, Kamikita-gun, Aomori 039-3212 (Japan)

    2014-12-15

    Reduced-activation ferritic/martensitic steels (RAFMs) are the primary candidate structural materials for fusion reactor blanket components. He bubbles, which formed under 14 MeV neutron irradiation, is considered to cause some mechanical property changes. In a previous study, Hasegawa et al. investigated the fracture behavior using Charpy impact test of He implanted F82H by 50 MeV α-particles with cyclotron accelerator, and the ductile brittle transition temperature (DBTT) was increased and intergranular fracture (IGF) was observed. However, the cause of the IGF was not shown in the previous study. To clarify the cause of the IGF of the He implanted F82H by 50 MeV α-particles with cyclotron accelerator, the microstructure of the He implanted F82H was investigated. After Charpy impact test at 233 K, the brittle fracture surface of the He implanted specimen was observed by SEM and TEM. By SEM observation, grain boundary surface was clearly observed from the bottom of the notch to a depth of about 400 μm. This area correspond to the He implanted region. On the other hand, at unimplanted region, river pattern was observed and transgranular fracture occurred. TEM observation revealed the He bubbles agglomeration at dislocations, lath boundaries, and grain boundaries, and the coarsening of precipitates on grain boundaries. IGF of the He implanted F82H was caused by both He bubbles and coarsening precipitates.

  12. Quantitative Evaluation of Aged AISI 316L Stainless Steel Sensitization to Intergranular Corrosion: Comparison Between Microstructural Electrochemical and Analytical Methods

    Science.gov (United States)

    Sidhom, H.; Amadou, T.; Sahlaoui, H.; Braham, C.

    2007-06-01

    The evaluation of the degree of sensitization (DOS) to intergranular corrosion (IGC) of a commercial AISI 316L austenitic stainless steel aged at temperatures ranging from 550 °C to 800 °C during 100 to 80,000 hours was carried out using three different assessment methods. (1) The microstructural method coupled with the Strauss standard test (ASTM A262). This method establishes the kinetics of the precipitation phenomenon under different aging conditions, by transmission electronic microscope (TEM) examination of thin foils and electron diffraction. The subsequent chromium-depleted zones are characterized by X-ray microanalysis using scanning transmission electronic microscope (STEM). The superimposition of microstructural time-temperature-precipitation (TTP) and ASTM A262 time-temperature-sensitization (TTS) diagrams provides the relationship between aged microstructure and IGC. Moreover, by considering the chromium-depleted zone characteristics, sensitization and desensitization criteria could be established. (2) The electrochemical method involving the double loop-electrochemical potentiokinetic reactivation (DL-EPR) test. The operating conditions of this test were initially optimized using the experimental design method on the bases of the reliability, the selectivity, and the reproducibility of test responses for both annealed and sensitized steels. The TTS diagram of the AISI 316L stainless steel was established using this method. This diagram offers a quantitative assessment of the DOS and a possibility to appreciate the time-temperature equivalence of the IGC sensitization and desensitization. (3) The analytical method based on the chromium diffusion models. Using the IGC sensitization and desensitization criteria established by the microstructural method, numerical solving of the chromium diffusion equations leads to a calculated AISI 316L TTS diagram. Comparison of these three methods gives a clear advantage to the nondestructive DL-EPR test when it is

  13. Sodium fire suppression

    Energy Technology Data Exchange (ETDEWEB)

    Malet, J C [DSN/SESTR, Centre de Cadarache, Saint-Paul-lez-Durance (France)

    1979-03-01

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  14. Sodium fire suppression

    International Nuclear Information System (INIS)

    Malet, J.C.

    1979-01-01

    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  15. A study of intergranular corrosion of austenitic stainless steel by electrochemical potentiodynamic reactivation, electron back-scattering diffraction and cellular automaton

    Energy Technology Data Exchange (ETDEWEB)

    Yu Xiaofei [Department of Chemistry, Shandong University, Jinan 250100 (China); Chen Shenhao [Department of Chemistry, Shandong University, Jinan 250100 (China); State Key Laboratory for Corrosion and Protection, Shenyang 110016 (China)], E-mail: shchen@sdu.edu.cn; Liu Ying; Ren Fengfeng [Department of Chemistry, Shandong University, Jinan 250100 (China)

    2010-06-15

    The impact of solution and sensitization treatments on the intergranular corrosion (IGC) of austenitic stainless steel (316) was studied by electrochemical potentiodynamic reactivation (EPR) test, and the results showed the degree of sensitization (DOS) decreased as solution treatment temperature and time went up, but it increased as sensitization temperature prolonged. Factors that affected IGC were investigated by field emission scanning electron microscope (FE-SEM) and electron back-scattering diffraction (EBSD). Furthermore, the precipitation evolution of Cr-rich carbides and the distribution of chromium concentration were simulated by cellular automaton (CA), clearly showing the effects of solution and sensitization treatments on IGC.

  16. Grain boundary selective oxidation and intergranular stress corrosion crack growth of high-purity nickel binary alloys in high-temperature hydrogenated water

    Energy Technology Data Exchange (ETDEWEB)

    Bruemmer, S. M.; Olszta, M. J.; Toloczko, M. B.; Schreiber, D. K.

    2018-02-01

    The effects of alloying elements in Ni-5at%X binary alloys on intergranular (IG) corrosion and stress corrosion cracking (SCC) have been assessed in 300-360°C hydrogenated water at the Ni/NiO stability line. Alloys with Cr or Al additions exhibited grain boundary oxidation and IGSCC, while localized degradation was not observed for pure Ni, Ni-Cu or Ni-Fe alloys. Environment-enhanced crack growth was determined by comparing the response in water and N2 gas. Results demonstrate that selective grain boundary oxidation of Cr and Al promoted IGSCC of these Ni alloys in hydrogenated water.

  17. Atraumatic First Rib Fracture

    Directory of Open Access Journals (Sweden)

    Koray Aydogdu

    2014-12-01

    Full Text Available Rib fractures are usually seen after a trauma, while atraumatic spontaneous rib fractures are quite rare. A first rib fracture identified in our 17 years old female patient who had not a history of trauma except lifting a heavy weight was examined in details in terms of the potential complications and followed-up for a long time. We presented our experience on this case with atraumatic first rib fracture that has different views for the etiology in light of the literature.

  18. Fracture mechanics safety approaches

    International Nuclear Information System (INIS)

    Roos, E.; Schuler, X.; Eisele, U.

    2004-01-01

    Component integrity assessments require the knowledge of reliable fracture toughness parameters characterising the initiation of the failure process in the whole relevant temperature range. From a large number of fracture mechanics tests a statistically based procedure was derived allowing to quantify the initiation of fracture toughness as a function of temperature as a closed function as well as the temperature dependence of the cleavage instability parameters. Alternatively to the direct experimental determination one also can use a correlation between fracture toughness and notch impact energy. (orig.)

  19. Scaphoid fractures in children

    Directory of Open Access Journals (Sweden)

    Gajdobranski Đorđe

    2014-01-01

    Full Text Available Introduction. Scaphoid fractures are rare in childhood. Diagnosis is very difficult to establish because carpal bones are not fully ossified. In suspected cases comparative or delayed radiography is used, as well as computerized tomography, magnetic resonance imaging, ultrasound and bone scintigraphy. Majority of scaphoid fractures are treated conservatively with good results. In case of delayed fracture healing various types of treatment are available. Objective. To determine the mechanism of injury, clinical healing process, types and outcome of treatment of scaphoid fractures in children. Methods. We retrospectively analyzed patients with traumatic closed fracture of the scaphoid bone over a ten-year period (2002-2011. The outcome of the treatment of “acute” scaphoid fracture was evaluated using the Mayo Wrist Score. Results. There were in total 34 patients, of mean age 13.8 years, with traumatic closed fracture of the scaphoid bone, whose bone growth was not finished yet. Most common injury mechanism was fall on outstretched arm - 76% of patients. During the examined period 31 children with “acute” fracture underwent conservative treatment, with average immobilization period of 51 days. Six patients were lost to follow-up. In the remaining 25 patients, after completed rehabilitation, functional results determined by the Mayo Wrist Score were excellent. Conclusion. Conservative therapy of “acute” scaphoid fractures is an acceptable treatment option for pediatric patients with excellent functional results.

  20. Pathological fractures in children

    Science.gov (United States)

    De Mattos, C. B. R.; Binitie, O.; Dormans, J. P.

    2012-01-01

    Pathological fractures in children can occur as a result of a variety of conditions, ranging from metabolic diseases and infection to tumours. Fractures through benign and malignant bone tumours should be recognised and managed appropriately by the treating orthopaedic surgeon. The most common benign bone tumours that cause pathological fractures in children are unicameral bone cysts, aneurysmal bone cysts, non-ossifying fibromas and fibrous dysplasia. Although pathological fractures through a primary bone malignancy are rare, these should be recognised quickly in order to achieve better outcomes. A thorough history, physical examination and review of plain radiographs are crucial to determine the cause and guide treatment. In most benign cases the fracture will heal and the lesion can be addressed at the time of the fracture, or after the fracture is healed. A step-wise and multidisciplinary approach is necessary in caring for paediatric patients with malignancies. Pathological fractures do not have to be treated by amputation; these fractures can heal and limb salvage can be performed when indicated. PMID:23610658

  1. Fracture of the styloid process associated with the mandible fracture

    Directory of Open Access Journals (Sweden)

    K N Dubey

    2013-01-01

    Full Text Available Fracture of the styloid process (SP of temporal bone is an uncommon injuries. Fracture of the SP can be associated with the facial injuries including mandible fracture. However, injury to the SP may be concealed and missed diagnosis may lead to the improper or various unnecessary treatments. A rare case of SP fracture associated with the ipsilateral mandibular fracture and also the diagnostic and management considerations of the SP fracture are discussed.

  2. The Process of Hydraulic Fracturing

    Science.gov (United States)

    Hydraulic fracturing, know as fracking or hydrofracking, produces fractures in a rock formation by pumping fluids (water, proppant, and chemical additives) at high pressure down a wellbore. These fractures stimulate the flow of natural gas or oil.

  3. [Trochanteric femoral fractures].

    Science.gov (United States)

    Douša, P; Čech, O; Weissinger, M; Džupa, V

    2013-01-01

    At the present time proximal femoral fractures account for 30% of all fractures referred to hospitals for treatment. Our population is ageing, the proportion of patients with post-menopausal or senile osteoporosis is increasing and therefore the number of proximal femoral fractures requiring urgent treatment is growing too. In the age category of 50 years and older, the incidence of these fractures has increased exponentially. Our department serves as a trauma centre for half of Prague and part of the Central Bohemia Region with a population of 1 150 000. Prague in particular has a high number of elderly citizens. Our experience is based on extensive clinical data obtained from the Register of Proximal Femoral Fractures established in 1997. During 14 years, 4280 patients, 3112 women and 1168 men, were admitted to our department for treatment of proximal femoral fractures. All patients were followed up until healing or development of complications. In the group under study, 82% were patients older than 70 years; 72% of those requiring surgery were in their seventies and eighties. Men were significantly younger than women (pfractures were 2.3-times more frequent in women than in men. In the category under 60 years, men significantly outnumbered women (pfractures were, on the average, eight years older than the patients with intertrochanteric fractures, which is a significant difference (pTrochanteric fractures accounted for 54.7% and femoral neck fractures for 45.3% of all fractures. The inter-annual increase was 5.9%, with more trochanteric than femoral neck fractures. There was a non-significant decrease in intertrochanteric (AO 31-A3) fractures. On the other hand, the number of pertrochanteric (AO 31-A1+2) fractures increased significantly (pfractures were treated with a proximal femoral nail; a short nail was used in 1260 and a long nail in 134 of them. A dynamic hip screw (DHS) was employed to treat 947 fractures. Distinguishing between pertrochanteric (21-A1

  4. Treatment of displaced mandibular condylar fracture with botulinum toxin A.

    Science.gov (United States)

    Akbay, Ercan; Cevik, Cengiz; Damlar, Ibrahim; Altan, Ahmet

    2014-04-01

    The aim of this case report is to discuss the effect on condylar reduction of botulinum toxin A treatment used in a child with displaced fracture at condylar neck of mandible. A 3-years old boy was admitted to our clinic for incomplete fracture of mandibular symphysis and displaced condylar fracture at the left side. An asymmetrical occlusal splint with intermaxillary fixation was used instead of open reduction and internal fixation because of incomplete fracture of symphysis and possible complications of condyle surgery. However, it was observed that condylar angulation persisted despite this procedure. Thus, botulinum toxin A was administered to masseter, temporalis and pterygoideus medialis muscles. At the end of first month, it was seen that mandibular condyle was almost completely recovered and that fusion was achieved. In conclusion, Botulinum A toxin injection aiming the suppression of masticatory muscle strength facilitates the reduction in the conservative management of displaced condyle in pediatric patients. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  5. Hand fracture - aftercare

    Science.gov (United States)

    ... an orthopedic surgeon if: Your metacarpal bones are broken and shifted out of place Your fingers do not line up correctly Your fracture nearly went through the skin Your fracture went through the skin Your pain is severe or becoming worse Self-care at Home You may have pain and swelling for 1 ...

  6. TIBIAL SHAFT FRACTURES.

    Science.gov (United States)

    Kojima, Kodi Edson; Ferreira, Ramon Venzon

    2011-01-01

    The long-bone fractures occur most frequently in the tibial shaft. Adequate treatment of such fractures avoids consolidation failure, skewed consolidation and reoperation. To classify these fractures, the AO/OTA classification method is still used, but it is worthwhile getting to know the Ellis classification method, which also includes assessment of soft-tissue injuries. There is often an association with compartmental syndrome, and early diagnosis can be achieved through evaluating clinical parameters and constant clinical monitoring. Once the diagnosis has been made, fasciotomy should be performed. It is always difficult to assess consolidation, but the RUST method may help in this. Radiography is assessed in two projections, and points are scored for the presence of the fracture line and a visible bone callus. Today, the dogma of six hours for cleaning the exposed fracture is under discussion. It is considered that an early start to intravenous antibiotic therapy and the lesion severity are very important. The question of early or late closure of the lesion in an exposed fracture has gone through several phases: sometimes early closure has been indicated and sometimes late closure. Currently, whenever possible, early closure of the lesion is recommended, since this diminishes the risk of infection. Milling of the canal when the intramedullary nail is introduced is still a controversial subject. Despite strong personal positions in favor of milling, studies have shown that there may be some advantage in relation to closed fractures, but not in exposed fractures.

  7. Physeal Fractures in Foals.

    Science.gov (United States)

    Levine, David G; Aitken, Maia R

    2017-08-01

    Physeal fractures are common musculoskeletal injuries in foals and should be included as a differential diagnosis for the lame or nonweightbearing foal. Careful evaluation of the patient, including precise radiographic assessment, is paramount in determining the options for treatment. Prognosis mostly depends on the patient's age, weight, and fracture location and configuration. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Reduction of intergranular exchange coupling and grain size for high Ku CoPt-based granular media: Metal-oxide buffer layer and multiple oxide boundary materials

    Directory of Open Access Journals (Sweden)

    Kim Kong Tham

    2018-05-01

    Full Text Available Investigation of magnetic properties and microstructure of granular media with various multiple oxides as the grain boundary material is reported. Saturation magnetization (Ms, uniaxial magnetocrystalline anisotropy (Ku, and magnetic grain diameter (GD of the granular media show linear correlation with volume weighted average for melting point (Tm of each oxides (Tmave. Ku of magnetic grains (Kugrain shows a trade-off relation with GD that it is a big challenge to satisfy both high Kugrain and small GD by only controlling Tmave. To obtain a granular medium with appropriate Kugrain, GD, and low degree of intergranular exchange coupling, the combination of Tmave control of grain boundary material by mixing oxides and employment of a buffer layer are required. Here the degree of intergranular exchange coupling is estimated from the slope of M-H loop at around coercivity (α. By applying this technique, a typical granular medium with Kugrain of 1.0×107 erg/cm3, GD of 5.1 nm, and α of 1.2 is realized.

  9. Localized deformation as a key precursor to initiation of intergranular stress corrosion cracking of austenitic stainless steels employed in nuclear power plants

    International Nuclear Information System (INIS)

    Karlsen, Wade; Diego, Gonzalo; Devrient, Bastian

    2010-01-01

    Cold-work has been associated with the occurrence of intergranular cracking of stainless steels employed in light water reactors. This study examined the deformation behavior of AISI 304, AISI 347 and a higher stacking fault energy model alloy subjected to bulk cold-work and (for 347) surface deformation. Deformation microstructures of the materials were examined and correlated with their particular mechanical response under different conditions of temperature, strain rate and degree of prior cold-work. Select slow-strain rate tensile tests in autoclaves enabled the role of local strain heterogeneity in crack initiation in pressurized water reactor environments to be considered. The high stacking fault energy material exhibited uniform strain hardening, even at sub-zero temperatures, while the commercial stainless steels showed significant heterogeneity in their strain response. Surface treatments introduced local cold-work, which had a clear effect on the surface roughness and hardness, and on near-surface residual stress profiles. Autoclave tests led to transgranular surface cracking for a circumferentially ground surface, and intergranular crack initiation for a polished surface.

  10. Strain-Annealing Based Grain Boundary Engineering to Evaluate its Sole Implication on Intergranular Corrosion in Extra-Low Carbon Type 304L Austenitic Stainless Steel

    Science.gov (United States)

    Pradhan, S. K.; Bhuyan, P.; Kaithwas, C.; Mandal, Sumantra

    2018-07-01

    Strain-annealing based thermo-mechanical processing has been performed to promote grain boundary engineering (GBE) in an extra-low carbon type austenitic stainless steel without altering the grain size and residual strain to evaluate its sole influence on intergranular corrosion. Single-step processing comprising low pre-strain ( 5 and 10 pct) followed by annealing at 1273 K for 1 hour have resulted in a large fraction of Σ3 n boundaries and significant disruption in random high-angle grain boundaries (RHAGBs) connectivity. This is due to the occurrence of prolific multiple twinning in these specimens as confirmed by their large twin-related domain and twin-related grain size ratio. Among the iterative processing, the schedule comprising two cycles of 10 and 5 pct deformation followed by annealing at 1173 K for 1 hour has yielded the optimum GBE microstructure with the grain size and residual strain akin to the as-received condition. The specimens subjected to the higher number of iterations failed to realize GBE microstructures due to the occurrence of partial recrystallization. Owing to the optimum grain boundary character distribution, the GBE specimen has exhibited remarkable resistance against sensitization and intergranular corrosion as compared to the as-received condition. Furthermore, the lower depth of percolation in the GBE specimen is due to the significant disruption of RHAGBs connectivity as confirmed from its large twin-related domain and lower fractal dimension.

  11. Development of Intergranular Residual Stress and Its Implication to Mechanical Behaviors at Elevated Temperatures in AL6XN Austenitic Stainless Steel

    Science.gov (United States)

    Hong, Yanyan; Li, Shilei; Li, Hongjia; Li, Jian; Sun, Guangai; Wang, Yan-Dong

    2018-05-01

    Neutron diffraction was used to investigate the residual lattice strains in AL6XN austenitic stainless steel subjected to tensile loading at different temperatures, revealing the development of large intergranular stresses after plastic deformation. Elastic-plastic self-consistent modeling was employed to simulate the micromechanical behavior at room temperature. The overall variations of the modeled lattice strains as a function of the sample direction with respect to the loading axis agree in general with the experimental values, indicating that dislocation slip is the main plastic deformation mode. At 300 °C, the serrated flow in the stress-strain curve and the great amount of slip bands indicate the appearance of dynamic strain aging. Except for promoting the local strain concentration, the long-range stress field caused by the planar slip bands near the grain boundaries is also attributed to the decrease in the experimental intergranular strains. An increase in the lattice strains localized at some specific specimen orientations for reflections at 600 °C may be explained by the segregation of solute atoms (Cr and Mo) at dislocation slip bands. The evolution of full-width at half-maximum demonstrates that the dynamic recovery indeed plays an important role in alleviating the local strain concentrations during tensile loading at 600 °C.

  12. Inter-granular glassy phases in the low-CaO-doped HIPed Si{sub 3}N{sub 4} ceramics. A review

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Hui [State Key Lab of High Performance Ceramics and Superfine Microstructures, Shanghai Inst. of Ceramics, Chinese Academy of Sciences, SH (China); Tanaka, Isao [Dept. of Materials Science and Engineering, Kyoto Univ. (Japan); Cannon, Rowland M. [Materials Science Div., Lawrence Berkeley National Lab., CA (United States); Pan, Xiaoqing [Dept. of Materials Science and Engineering, Michigan Univ., Ann Arbor (United States); Ruehle, Manfred [Max Planck Inst. for Metals Research, Stuttgart (Germany)

    2010-01-15

    This review outlines the essence of a progressive study on the glassy inter-granular film (IGF) in a model ceramic system, the low-CaO-doped HIPed high-purity Si{sub 3}N{sub 4}. This was initiated from the finding of a systematic variation of equilibrium IGF thickness following the dopant chemistry, manifesting its fundamental important to ceramic processing. By employing analytical transmission electron microscopy to measure the local chemistry in IGF, however, significant discrepancy was found between trends of local IGF chemistry and thickness. A stable IGF composition was revealed in this system, while a bi-level distribution of Ca segregation establishes a correspondence between the IGF structure and the surface crystallography. The detection of similar levels of nitrogen in IGF through the whole series further supports the presence of a rather stable IGF chemistry. After the saturation of dopants in the stable IGF, extra CaO was found to re-distribute in pockets by enrichment at tips, leading to a liquid phase separation with the Ca-rich phase wetting the entrance zone contacting IGF. The perspective for establishing a comprehensive correlation between the inter-granular phases and the bi-modal microstructure induced by faster growth of basal facets is briefly discussed to pave the way for future work. (orig.)

  13. Effect of laser heat treatment on intergranular corrosion of austenitic stainless steel; Austenite kei stainless ko no ryukai fushoku kanjusei ni oyobosu laser netsushori no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Osawa, M.; Yoneyama, T. [Tokyo Denki University, Tokyo (Japan). Faculty of Engineering; Isshiki, Y. [Tokyo Metropolitan Industrial Technology Center, Tokyo (Japan)

    1995-03-15

    The laser heat treatment of SUS304 steel was studied to lower the intergranular corrosion sensitivity of austenitic stainless steel. By the short-time heating around 923K, the SUS304 steel is sensitized to the intergranular corrosion with the deposition of Cr carbide into the granular field of crystals. To recover it, it is necessary to solidly dissolve, and simultaneously, quickly cool the Cr carbide above 1273K. For such solution heat treatment, CO2 laser beams were used with the treatment condition that the power and beam diameter were 800 to 1200W and 0.3 to 0.64cm, respectively. Regardless of both power density and beam diameter, the desensitization was observed at heating temperatures above 1323K. As a result of calculation by simulation, the solid dissolution of Cr carbide and recovery of Cr`s depletion zone in the granular field of crystals took place in a very short time at heating temperatures above 1323K. It agreed well with the experimental result. The laser beams are effective in the solution heat treatment of stainless steel. 14 refs., 15 figs., 1 tab.

  14. Reduction of intergranular exchange coupling and grain size for high Ku CoPt-based granular media: Metal-oxide buffer layer and multiple oxide boundary materials

    Science.gov (United States)

    Tham, Kim Kong; Kushibiki, Ryosuke; Kamada, Tomonari; Hinata, Shintaro; Saito, Shin

    2018-05-01

    Investigation of magnetic properties and microstructure of granular media with various multiple oxides as the grain boundary material is reported. Saturation magnetization (Ms), uniaxial magnetocrystalline anisotropy (Ku), and magnetic grain diameter (GD) of the granular media show linear correlation with volume weighted average for melting point (Tm) of each oxides (Tmave). Ku of magnetic grains (Kugrain) shows a trade-off relation with GD that it is a big challenge to satisfy both high Kugrain and small GD by only controlling Tmave. To obtain a granular medium with appropriate Kugrain, GD, and low degree of intergranular exchange coupling, the combination of Tmave control of grain boundary material by mixing oxides and employment of a buffer layer are required. Here the degree of intergranular exchange coupling is estimated from the slope of M-H loop at around coercivity (α). By applying this technique, a typical granular medium with Kugrain of 1.0×107 erg/cm3, GD of 5.1 nm, and α of 1.2 is realized.

  15. Treatment of midfacial fractures

    International Nuclear Information System (INIS)

    Schubert, J.

    2007-01-01

    Fractures of the midface constitute half of all traumas involving facial bones. Computed tomography is very useful in primary diagnosis. Isolated fractures of the nasal bone and lateral midfacial structures may be diagnosed sufficiently by conventional X-rays. An exact description of the fracture lines along the midfacial buttresses is essential for treatment planning. For good aesthetics and function these have to be reconstructed accurately, which can be checked with X-rays. The treatment of midfacial fractures has been revolutionized over the last two decades. A stable three-dimensional reconstruction of the facial shape is now possible and the duration of treatment has shortened remarkably. The frequently occurring isolated fractures in the lateral part of the midface may be treated easily and effectively by semisurgical methods such as the Gillies procedure or hook-repositioning. (orig.)

  16. Dating fractures in infants

    Energy Technology Data Exchange (ETDEWEB)

    Halliday, K.E., E-mail: kath.halliday@nuh.nhs.uk [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Broderick, N J; Somers, J M [Department of Radiology, Nottingham University Hospitals, Queen' s Medical Centre, Nottingham (United Kingdom); Hawkes, R [Department of Radiology, Paul O' Gorman Building, Bristol (United Kingdom)

    2011-11-15

    Aim: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. Materials and methods: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. Results: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. Conclusion: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.

  17. Dating fractures in infants

    International Nuclear Information System (INIS)

    Halliday, K.E.; Broderick, N.J.; Somers, J.M.; Hawkes, R.

    2011-01-01

    Aim: To document the timing of the appearance of the radiological features of fracture healing in a group of infants in which the date of injury was known and to assess the degree of interobserver agreement. Materials and methods: Three paediatric radiologists independently assessed 161 images of 37 long bone fractures in 31 patients aged 0-44 months. The following features were assessed: soft-tissue swelling, subperiosteal new bone formation (SPNBF), definition of fracture line, presence or absence of callus, whether callus was well or ill defined, and the presence of endosteal callus. Results: Agreement between observers was only moderate for all discriminators except SPNBF. SPNBF was invariably seen after 11 days but was uncommon before this time even in the very young. In one case SPNBF was seen at 4 days. Conclusion: With the exception of SPNBF, the criteria relied on to date fractures are either not reproducible or are poor discriminators of fracture age.

  18. Tibial Plateau Fractures

    DEFF Research Database (Denmark)

    Elsøe, Rasmus

    This PhD thesis reported an incidence of tibial plateau fractures of 10.3/100,000/year in a complete Danish regional population. The results reported that patients treated for a lateral tibial plateau fracture with bone tamp reduction and percutaneous screw fixation achieved a satisfactory level...... with only the subgroup Sport significantly below the age matched reference population. The thesis reports a level of health related quality of life (Eq5d) and disability (KOOS) significantly below established reference populations for patients with bicondylar tibial plateau fracture treated with a ring...... fixator, both during treatment and at 19 months following injury. In general, the thesis demonstrates that the treatment of tibial plateau fractures are challenging and that some disabilities following these fractures must be expected. Moreover, the need for further research in the area, both with regard...

  19. Fracturing formations in wells

    Energy Technology Data Exchange (ETDEWEB)

    Daroza, R A

    1964-05-15

    This well stimulation method comprises introducing through the well bore a low-penetrating, dilatant fluid, and subjecting the fluid to sufficient pressure to produce fractures in the formation. The fluid is permitted to remain in contact with the formation so as to become diluted by the formation fluids, and thereby lose its properties of dilatancy. Also, a penetrating fluid, containing a propping agent suspended therein, in introduced into contact with the fractures at a pressure substantially reduced with respect to that pressure which would have been required, prior to the fracturing operation performed using the low-penetrating dilatant fluid. The propping agent is deposited within the fractures, and thereafter, fluid production is resumed from the fractured formation. (2 claims)

  20. Pressure suppression device

    International Nuclear Information System (INIS)

    Mizumachi, Wataru; Fukuda, Akira; Kitaguchi, Hidemi; Shimizu, Toshiaki.

    1976-01-01

    Object: To relieve and absorb impact wave vibrations caused by steam and non-condensed gases releasing into the pressure suppression chamber at the time of an accident. Structure: The reactor container is filled with inert gases. A safety valve attached main steam pipe is provided to permit the excessive steam to escape, the valve being communicated with the pressure suppression chamber through an exhaust pipe. In the pressure suppression chamber, a doughnut-like cylindrical outer wall is filled at its bottom with pool water to condense the high temperature vapor released through the exhaust pipe. A head portion of a vent tube which leads the exhaust pipe is positioned at the top, and a down comer and an exhaust vent tube are locked by means of steady rests. At the bottom is mounted a pressure adsorber device which adsorbs a pressure from the pool water. (Kamimura, M.)

  1. Fracture toughness of copper-base alloys for ITER applications: A preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, D.J.; Zinkle, S.J.; Rowcliffe, A.F. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    Oxide-dispersion strengthened copper alloys and a precipitation-hardened copper-nickel-beryllium alloy showed a significant reduction in toughness at elevated temperature (250{degrees}C). This decrease in toughness was much larger than would be expected from the relatively modest changes in the tensile properties over the same temperature range. However, a copper-chromium-zirconium alloy strengthened by precipitation showed only a small decrease in toughness at the higher temperatures. The embrittled alloys showed a transition in fracture mode, from transgranular microvoid coalescence at room temperature to intergranular with localized ductility at high temperatures. The Cu-Cr-Zr alloy maintained the ductile microvoid coalescence failure mode at all test temperatures.

  2. Thyroxin hormone suppression treatment

    International Nuclear Information System (INIS)

    Samuel, A.M.

    1999-01-01

    One of the important modalities of treatment of thyroid cancer (TC) after surgery is the administration of thyroxin as an adjuvant treatment. The analysis supports the theory that thyroid suppression plays an important role in patient management. 300 μg of thyroxin, as this is an adequate dose for suppression is given. Ideally the dose should be tailored by testing s-TSH levels. However, since a large number of the patients come from out station cities and villages this is impractical. We therefore depend on clinical criteria of hyperthyroid symptoms and adjust the dose. Very few patients need such adjustment

  3. Computed tomograms of blowout fracture

    International Nuclear Information System (INIS)

    Ito, Haruhide; Hayashi, Minoru; Shoin, Katsuo; Hwang, Wen-Zern; Yamamoto, Shinjiro; Yonemura, Taizo.

    1985-01-01

    We studied 18 cases of orbital fractures, excluding optic canal fracture. There were 11 cases of pure blowout fracture and 3 of the impure type. The other 4 cases were orbital fractures without blowout fracture. The cardinal syndromes were diplopia, enophthalmos, and sensory disturbances of the trigeminal nerve in the pure type of blowout fracture. Many cases of the impure type of blowout fracture or of orbital fracture showed black eyes or a swelling of the eyelids which masked enophthalmos. Axial and coronal CT scans demonstrated: 1) the orbital fracture, 2) the degree of enophthalmos, 3) intraorbital soft tissue, such as incarcerated or prolapsed ocular muscles, 4) intraorbital hemorrhage, 5) the anatomical relation of the orbital fracture to the lacrimal canal, the trochlea, and the trigeminal nerve, and 6) the lesions of the paranasal sinus and the intracranial cavity. CT scans play an important role in determining what surgical procedures might best be employed. Pure blowout fractures were classified by CT scans into these four types: 1) incarcerating linear fracture, 2) trapdoor fracture, 3) punched-out fracture, and 4) broad fracture. Cases with severe head injury should be examined to see whether or not blowout fracture is present. If the patients are to hope to return to society, a blowout fracture should be treated as soon as possible. (author)

  4. Computed tomograms of blowout fracture

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Haruhide; Hayashi, Minoru; Shoin, Katsuo; Hwang, Wen-Zern; Yamamoto, Shinjiro; Yonemura, Taizo

    1985-02-01

    We studied 18 cases of orbital fractures, excluding optic canal fracture. There were 11 cases of pure blowout fracture and 3 of the impure type. The other 4 cases were orbital fractures without blowout fracture. The cardinal syndromes were diplopia, enophthalmos, and sensory disturbances of the trigeminal nerve in the pure type of blowout fracture. Many cases of the impure type of blowout fracture or of orbital fracture showed black eyes or a swelling of the eyelids which masked enophthalmos. Axial and coronal CT scans demonstrated: 1) the orbital fracture, 2) the degree of enophthalmos, 3) intraorbital soft tissue, such as incarcerated or prolapsed ocular muscles, 4) intraorbital hemorrhage, 5) the anatomical relation of the orbital fracture to the lacrimal canal, the trochlea, and the trigeminal nerve, and 6) the lesions of the paranasal sinus and the intracranial cavity. CT scans play an important role in determining what surgical procedures might best be employed. Pure blowout fractures were classified by CT scans into these four types: 1) incarcerating linear fracture, 2) trapdoor fracture, 3) punched-out fracture, and 4) broad fracture. Cases with severe head injury should be examined to see whether or not blowout fracture is present. If the patients are to hope to return to society, a blowout fracture should be treated as soon as possible. (author).

  5. Evaluation of the Intrinsic and Extrinsic Fracture Behavior of Iron Aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, B.R.

    2001-01-11

    In this paper, we first present the status of our computational modeling study of the thermal expansion coefficient of Fe/Al over a wide range of temperature and evaluate its dependence on selected additives. This will be accomplished by applying an isobaric Monte Carlo technique. The required total energy of the sample will be computed by using a tight-binding (TB) method that allows us to significantly increase the size of the computational data base without reducing the accuracy of the calculations. The parameters of the TB Hamiltonian are fitted to reproduce the band structure obtained by our quantum mechanical full-potential LMTO calculations. The combination of the three methods mentioned above creates an effective approach to the computation of the physical properties of the transition-metal aluminides and it can be extended to alloys with more than two components. At present, we are using a simplified approach for a first-round of results; and as a test of the simplified approach, have obtained excellent agreement with experiment for aluminum. Our previous experimental results showed that, because of their smaller grain size, FA-187 and FA-189 are extrinsically more susceptible to environmental embrittlement than FA-186 under low strain loading condition. To further investigate the grain boundary size effect as related to the susceptibility of hydrogen embrittlement, we conducted comparative finite element modeling simulations of initial intergranular fracture of two iron aluminides (FA186 and FA189) due to hydrogen embrittlement. Sequentially coupled stress and mass diffusion analyses are carried out to determine crack-tip stress state and the extent of hydrogen diffusion at the crack tip region, and a proper failure criteria is then adopted to simulate the intergranular fracture. Good qualitative agreement between the modeling predictions and experimental results is observed.

  6. Radiological diagnosis of fractures

    International Nuclear Information System (INIS)

    Finlay, D.B.L.; Allen, M.J.

    1984-01-01

    This book is about radiology of fractures. While it contains sections of clinical features it is not intended that readers should rely entirely upon these for the diagnosis and management of the injured patient. As in the diagnosis and treatment of all medical problems, fracture management must be carried out in a logical step-by-step fashion - namely, history, examination, investigation, differential diagnosis, diagnosis and then treatment. Each section deals with a specific anatomical area and begins with line drawings of the normal radiographs demonstrating the anatomy. Accessory views that may be requested, and the indications for these, are included. Any radiological pitfalls for the area in general are then described. The fractures in adults are then examined in turn, their radiological features described, and any pitfalls in their diagnosis discussed. A brief note of important clinical findings is included. A brief mention is made of pediatric fractures which are of significance and their differences to the adult pattern indicated. Although fractures can be classified into types with different characteristics, in life every fracture is individual. Fractures by and large follow common patterns, but many have variations

  7. Spontaneous rib fractures.

    Science.gov (United States)

    Katrancioglu, Ozgur; Akkas, Yucel; Arslan, Sulhattin; Sahin, Ekber

    2015-07-01

    Other than trauma, rib fracture can occur spontaneously due to a severe cough or sneeze. In this study, patients with spontaneous rib fractures were analyzed according to age, sex, underlying pathology, treatment, and complications. Twelve patients who presented between February 2009 and February 2011 with spontaneous rib fracture were reviewed retrospectively. The patients' data were evaluated according to anamnesis, physical examination, and chest radiographs. The ages of the patients ranged from 34 to 77 years (mean 55.91 ± 12.20 years), and 7 (58.4%) were male. All patients had severe cough and chest pain. The fractures were most frequently between 4th and 9th ribs; multiple rib fractures were detected in 5 (41.7%) patients. Eight (66.7%) patients had chronic obstructive pulmonary disease, 2 (16.7%) had bronchial asthma, and 2 (16.7%) had osteoporosis. Bone densitometry revealed a high risk of bone fracture in all patients. Patients with chronic obstructive pulmonary disease or bronchial asthma had been treated with high-dose steroids for over a year. Spontaneous rib fracture due to severe cough may occur in patients with osteoporosis, chronic obstructive pulmonary disease, or bronchial asthma, receiving long-term steroid therapy. If these patients have severe chest pain, chest radiography should be performed to check for bone lesions. © The Author(s) 2015.

  8. Why ductile fracture mechanics

    International Nuclear Information System (INIS)

    Ritchie, R.O.

    1983-01-01

    Until recently, the engineering application of fracture mechanics has been specific to a description of macroscopic fracture behavior in components and structural parts which remain nominally elastic under loading. While this approach, termed linear elastic fracture mechanics, has been found to be invaluable for the continuum analysis of crack growth in brittle and high strength materials, it is clearly inappropriate for characterizing failure in lower strength ductile alloys where extensive inelastic deformation precedes and accompanies crack initiation and subsequent propagation. Accordingly, much effort has been devoted in recent years toward the development of nonlinear or ductile fracture mechanics methodology to characterize fracture behavior under elastic/plastic conditions; an effort which has been principally motivated by problems in nuclear industry. In this paper, the concepts of ductile (elastic/plastic) fracture mechanics are introduced and applied to the problem of both stationary and nonstationary cracks. Specifically, the limitations inherent in this approach are defined, together with a description of the microstructural considerations and applications relevant to the failure of ductile materials by fracture, fatigue, and creep

  9. Orbital wall fractures

    International Nuclear Information System (INIS)

    Iinuma, Toshitaka; Ishio, Ken-ichirou; Yoshinami, Hiroyoshi; Kuriyama, Jun-ichi; Hirota, Yoshiharu.

    1993-01-01

    A total of 59 cases of mild facial fractures (simple orbital wall fractures, 34 cases, other facial fractures, 25 cases) with the clinical suspects of orbital wall fractures were evaluated both by conventional views (Waters' and Caldwell views) and coronal CT scans. Conventional views were obtained, as an average, after 4 days and CT after 7 days of injuries. Both the medial wall and the floor were evaluated at two sites, i.e., anterior and posterior. The ethmoid-maxillary plate was also included in the study. The degree of fractures was classified as, no fractures, fractures of discontinuity, dislocation and fragmentation. The coronal CT images in bone window condition was used as reference and the findings were compared between conventional views and CT. The correct diagnosis was obtained as follows: orbital floor (anterior, 78%, posterior, 73%), medial orbital wall (anterior, 72%, posterior, 72%) and ethmoid-maxillary plate (64%). The false positive diagnosis was as follows: orbital floor (anterior only, 13%), medial orbital wall (anterior only, 7%) and ethmoid-maxillary plate (11%). The false negative diagnosis was as follows: orbital floor (anterior, 9%, posterior, 10%), medial orbital wall (anterior, 21%, posterior, 28%) and ethmoid-maxillary plate (21%). The results were compared with those of others in the past. (author)

  10. Chance Fracture Secondary to a Healed Kyphotic Compression Osteoporotic Fracture

    Directory of Open Access Journals (Sweden)

    Teh KK

    2009-11-01

    Full Text Available Chance fracture is an unstable vertebral fracture, which usually results from a high velocity injury. An elderly lady with a previously healed osteoporotic fracture of the T12 and L1 vertebra which resulted in a severe kyphotic deformity subsequently sustained a Chance fracture of the adjacent L2 vertebrae after a minor fall. The previously fracture left her with a deformity which resulted in significant sagittal imbalance therefore predisposing her to this fracture. This case highlights the importance of aggressive treatment of osteoporotic fractures in order to prevent significant sagittal imbalance from resultant (i.e. kyphotic deformity.

  11. Subtrochanteric and diaphyseal femur fractures in patients treated with alendronate: a register-based national cohort study

    DEFF Research Database (Denmark)

    Abrahamsen, Bo; Eiken, Pia; Eastell, Richard

    2009-01-01

    Alendronate (aln) is a potent bisphosphonate with a prolonged duration of action. Recent reports have found long-term aln use to be common in patients with subtrochanteric or proximal diaphyseal femur fracture, raising concerns that these fractures could be a consequence of excessive suppression...

  12. Pressure suppressing device

    International Nuclear Information System (INIS)

    Naito, Makoto.

    1980-01-01

    Purpose: To prevent the pressure in the reactor container from excessively increasing even when vapor leaks from the dry well to a space of the suppression chamber, without passing though the suppression pool at the time of loss of coolant accident. Constitution: When vapor of a high temperature and a high pressure at the time of loss of coolant accident flows from the dry well to the suppression chamber without passing through suppression pool water, vapor dose not condense with pool water, and therefore the pressure within the chamber abnormally increases. For this reason, this abnormal pressure is detected by a pressure detector thereby to start the operations of a blower and a pump. By starting the blower, the pressure in the dry well becomes lower than the pressure in the chamber, and vapor entirely passes through the pool water and entirely condenses with the pool water. By starting the pump, the pool water is sprayed over the space of the chamber, and vapor in the space is condensed. (Yoshino, Y.)

  13. A Rare Nasal Bone Fracture: Anterior Nasal Spine Fracture

    Directory of Open Access Journals (Sweden)

    Egemen Kucuk

    2014-04-01

    Full Text Available Anterior nasal spine fractures are a quite rare type of nasal bone fractures. Associated cervical spine injuries are more dangerous than the nasal bone fracture. A case of the anterior nasal spine fracture, in a 18-year-old male was presented. Fracture of the anterior nasal spine, should be considered in the differential diagnosis of the midface injuries and also accompanying cervical spine injury should not be ignored.

  14. Fracture characteristics in Japanese rock

    International Nuclear Information System (INIS)

    Ijiri, Yuji; Sawada, Atsushi; Akahori, Kuniaki

    1999-11-01

    It is crucial for the performance assessment of geosphere to evaluate the characteristics of fractures that can be dominant radionuclide migration pathways from a repository to biosphere. This report summarizes the characteristics of fractures obtained from broad literature surveys and the fields surveys at the Kamaishi mine in northern Japan and at outcrops and galleries throughout the country. The characteristics of fractures described in this report are fracture orientation, fracture shape, fracture frequency, fracture distribution in space, transmissivity of fracture, fracture aperture, fracture fillings, alteration halo along fracture, flow-wetted surface area in fracture, and the correlation among these characteristics. Since granitic rock is considered the archetype fractured media, a large amount of fracture data is available in literature. In addition, granitic rock has been treated as a potential host rock in many overseas programs, and has JNC performed a number of field observations and experiments in granodiorite at the Kamaishi mine. Therefore, the characteristics of fractures in granitic rock are qualitatively and quantitatively clarified to some extent in this report, while the characteristics of fractures in another rock types are not clarified. (author)

  15. Aspects of modern fracture statistics

    International Nuclear Information System (INIS)

    Tradinik, W.; Pabst, R.F.; Kromp, K.

    1981-01-01

    This contribution begins with introductory general remarks about fracture statistics. Then the fundamentals of the distribution of fracture probability are described. In the following part the application of the Weibull Statistics is justified. In the fourth chapter the microstructure of the material is considered in connection with calculations made in order to determine the fracture probability or risk of fracture. (RW) [de

  16. Fracture Phenomena in Amorphous Selenium

    DEFF Research Database (Denmark)

    Lindegaard-Andersen, Asger; Dahle, Birgit

    1966-01-01

    Fracture surfaces of amorphous selenium broken in flexure at room temperature have been studied. The fracture velocity was found to vary in different regions of the fracture surface. Peculiar features were observed in a transition zone between fast and slower fracture. In this zone cleavage steps...

  17. Management of Penile Fracture and its Outcome

    International Nuclear Information System (INIS)

    Khan, Z. I.

    2013-01-01

    Objective: To describe the management and outcome of patients with penile fracture. Study Design: Case series. Place and Duration of Study: Department of Urology and Renal Transplantation, Jinnah Hospital, Lahore, from March 2008 to March 2011. Methodology: Sixteen patients presenting with clinical findings / history of penile fracture were included in this study. Diagnosis was made on the basis of history and clinical findings. Surgical exploration and repair was done on the same day. In all patients, a subcoronal circumferential degloving incision was made. Rent location and dimensions management and postoperative complication were noted. Postoperatively, erection was suppressed for 4 - 5 days. All patients were discharged with advice of avoidance of sex for about 8 weeks. Patients were followed-upto 6 months. Results: Majority of the patients (87.5%) were married and 13 (81.25%) were aged 18 - 45 years. The typical findings recorded in 100.0% patients were erection at time of fracture, detumescence, swelling and ecchymosis. Audible crackling sound and pain was present in 13 (81.25%) patients. Ten (62.5%) patients had rent in the proximal part of penile shaft and right lateral tear was present in 11 (68.75%) patients. Blood clots were evacuated and closure of rent was done with vicryl 2/0 (interrupted stitches). 100.0% patients had uneventful recovery with only 3 (18.75%) patients developed right chordae of erect penis after treatment. All (100.0%) patients were potent and without any problem of erection. Conclusion: Penile fracture is under-reported. A trauma to erect penis is essential to cause fracture. Surgical exploration and repair is the treatment of choice. (author)

  18. Stress localization in BCC polycrystals and its implications on the probability of brittle fracture

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, Ludovic [CEA, DEN, SRMA, 91191 Gif sur Yvette Cedex (France); Gelebart, Lionel, E-mail: lionel.gelebart@cea.fr [CEA, DEN, SRMA, 91191 Gif sur Yvette Cedex (France); Dakhlaoui, Rim; Marini, Bernard [CEA, DEN, SRMA, 91191 Gif sur Yvette Cedex (France)

    2011-07-15

    Highlights: {yields} Intergranular stress distributions in a bainitic steel. {yields} Comparison of local mean stress field with neutron diffraction results. {yields} Application of the local stress distribution in a brittle fracture model. - Abstract: The evaluation of the reliability of pressure vessels in nuclear plants relies on the evaluation of failure probability models. Micromechanical approaches are of great interest to refine their description, to better understand the underlying mechanisms leading to failure, and finally to improve the prediction of these models. The main purpose of this paper is to introduce the stress heterogeneities arising within the polycrystal in a probabilistic modeling of brittle fracture. Stress heterogeneities are evaluated from Finite-Element simulations performed on a large number of Statistical Volume Elements. Results are validated both on the measured averaged behavior and on the averaged stresses measured by neutron diffraction in five specific orientations. A probabilistic model for brittle fracture is then presented accounting for the carbide distribution and the stress distribution evaluated previously inside an elementary volume V{sub 0}. Results are compared to a 'Beremin type' approach, assuming a homogeneous stress state inside V{sub 0}.

  19. Vertebral Compression Fractures

    Science.gov (United States)

    ... and monitored to avoid putting pressure on the ribs that can cause new fractures. Surgical Procedures • When there is severe incapacitating pain • When healing is delayed or when bone fragments ...

  20. Paediatric talus fracture.

    LENUS (Irish Health Repository)

    Byrne, Ann-Maria

    2012-01-01

    Paediatric talus fractures are rare injuries resulting from axial loading of the talus against the anterior tibia with the foot in dorsiflexion. Skeletally immature bone is less brittle, with higher elastic resistance than adult bone, thus the paediatric talus can sustain higher forces before fractures occur. However, displaced paediatric talus fractures and those associated with high-energy trauma have been associated with complications including avascular necrosis, arthrosis, delayed union, neurapraxia and the need for revision surgery. The authors present the rare case of a talar neck fracture in a skeletally immature young girl, initially missed on radiological review. However, clinical suspicion on the part of the emergency physician, repeat examination and further radiographic imaging revealed this rare paediatric injury.

  1. Elevated temperature fracture mechanics

    International Nuclear Information System (INIS)

    Tomkins, B.

    1979-01-01

    The application of fracture mechanics concepts to cracks at elevated temperatures is examined. Particular consideration is given to the characterisation of crack tip stress-strain fields and parameters controlling crack extension under static and cyclic loads. (author)

  2. Stress fractures in athletes

    International Nuclear Information System (INIS)

    Kirschberger, R.; Henning, A.; Graff, K.H.

    1984-01-01

    The early exclusion of the presence of a stress fracture may be decisive for the success of an athlete. Scintigraphy with a bone-seeking radiopharmaceutical is suitable for the early detection of stress lesions. Of 30 athletes, fractures were demonstrated in 17 whereas in 6 they were excluded. We found most fractures in the tarsal bones such as os naviculare pedis, ossa cuneiformia and talus. The type of sport engaged in appears to be an important factor in determining the location of the fracture. Scintiphotos were taken in several views using region of interest techniques and two phase-scintigraphy. This method is considered to be useful for localization and follow-up of skeletal stress lesions as well as for differential diagnosis. (orig.) [de

  3. Stress fractures in athletes

    Energy Technology Data Exchange (ETDEWEB)

    Kirschberger, R; Henning, A; Graff, K H

    1984-12-01

    The early exclusion of the presence of a stress fracture may be decisive for the success of an athlete. Scintigraphy with a bone-seeking radiopharmaceutical is suitable for the early detection of stress lesions. Of 30 athletes, fractures were demonstrated in 17 whereas in 6 they were excluded. We found most fractures in the tarsal bones such as os naviculare pedis, ossa cuneiformia and talus. The type of sport engaged in appears to be an important factor in determining the location of the fracture. Scintiphotos were taken in several views using region of interest techniques and two phase-scintigraphy. This method is considered to be useful for localization and follow-up of skeletal stress lesions as well as for differential diagnosis.

  4. Fatigue and insufficiency fractures

    International Nuclear Information System (INIS)

    Lodwick, G.S.; Rosenthal, D.I.; Kattapuram, S.V.; Hudson, T.M.

    1987-01-01

    The incidence of stress fracture is increasing. In our younger society this is due largely to a preocupation with physical conditioning, but in our elderly population it is due to improved recognition and better methods of detection and diagnosis. Stress fracture of the elderly is an insufficiency fracture which occurs in the spine, the pelvis, the sacrum and other bones afflicted with disorders which cause osteopenia. Stress fracture is frequently misdiagnosed as a malignant lesion of bone resulting in biopsy. Scintiscanning provides the greatest frequency of detection, while computed tomography often provides the definitive diagnosis. With increased interest and experience a better insight into the disease has been achieved, and what was once thought of as a simple manifestation of mechanical stress is now known to be an orderly, complex pattern of physiological changes in bone which conform to a model by Frost. The diffuse nature of these changes can be recognized by scintigraphy, radiography and magnetic resonance imaging. 27 refs.; 8 figs

  5. Ontology of fractures

    Science.gov (United States)

    Zhong, Jian; Aydina, Atilla; McGuinness, Deborah L.

    2009-03-01

    Fractures are fundamental structures in the Earth's crust and they can impact many societal and industrial activities including oil and gas exploration and production, aquifer management, CO 2 sequestration, waste isolation, the stabilization of engineering structures, and assessing natural hazards (earthquakes, volcanoes, and landslides). Therefore, an ontology which organizes the concepts of fractures could help facilitate a sound education within, and communication among, the highly diverse professional and academic community interested in the problems cited above. We developed a process-based ontology that makes explicit specifications about fractures, their properties, and the deformation mechanisms which lead to their formation and evolution. Our ontology emphasizes the relationships among concepts such as the factors that influence the mechanism(s) responsible for the formation and evolution of specific fracture types. Our ontology is a valuable resource with a potential to applications in a number of fields utilizing recent advances in Information Technology, specifically for digital data and information in computers, grids, and Web services.

  6. Fracture and Healing of Rock Salt Related to Salt Caverns

    International Nuclear Information System (INIS)

    Chan, K.S.; Fossum, A.F.; Munson, D.E.

    1999-01-01

    In recent years, serious investigations of potential extension of the useful life of older caverns or of the use of abandoned caverns for waste disposal have been of interest to the technical community. All of the potential applications depend upon understanding the reamer in which older caverns and sealing systems can fail. Such an understanding will require a more detailed knowledge of the fracture of salt than has been necessary to date. Fortunately, the knowledge of the fracture and healing of salt has made significant advances in the last decade, and is in a position to yield meaningful insights to older cavern behavior. In particular, micromechanical mechanisms of fracture and the concept of a fracture mechanism map have been essential guides, as has the utilization of continuum damage mechanics. The Multimechanism Deformation Coupled Fracture (MDCF) model, which is summarized extensively in this work was developed specifically to treat both the creep and fracture of salt, and was later extended to incorporate the fracture healing process known to occur in rock salt. Fracture in salt is based on the formation and evolution of microfractures, which may take the form of wing tip cracks, either in the body or the boundary of the grain. This type of crack deforms under shear to produce a strain, and furthermore, the opening of the wing cracks produce volume strain or dilatancy. In the presence of a confining pressure, microcrack formation may be suppressed, as is often the case for triaxial compression tests or natural underground stress situations. However, if the confining pressure is insufficient to suppress fracture, then the fractures will evolve with time to give the characteristic tertiary creep response. Two first order kinetics processes, closure of cracks and healing of cracks, control the healing process. Significantly, volume strain produced by microfractures may lead to changes in the permeability of the salt, which can become a major concern in

  7. Osteoporotic fractures in older adults

    OpenAIRE

    Colón-Emeric, Cathleen S.; Saag, Kenneth G.

    2006-01-01

    Osteoporotic fractures are emerging as a major public health problem in the aging population. Fractures result in increased morbidity, mortality and health expenditures. This article reviews current evidence for the management of common issues following osteoporotic fractures in older adults including: (1) thromboembolism prevention; (2) delirium prevention; (3) pain management; (4) rehabilitation; (5) assessing the cause of fracture; and (6) prevention of subsequent fractures. Areas for prac...

  8. Classical fracture mechanics methods

    International Nuclear Information System (INIS)

    Schwalbe, K.H.; Heerens, J.; Landes, J.D.

    2007-01-01

    Comprehensive Structural Integrity is a reference work which covers all activities involved in the assurance of structural integrity. It provides engineers and scientists with an unparalleled depth of knowledge in the disciplines involved. The new online Volume 11 is dedicated to the mechanical characteristics of materials. This paper contains the chapter 11.02 of this volume and is structured as follows: Test techniques; Analysis; Fracture behavior; Fracture toughness tests for nonmetals

  9. [Periprosthetic knee fractures].

    Science.gov (United States)

    Mittlmeier, T; Beck, M; Bosch, U; Wichelhaus, A

    2016-01-01

    The cumulative incidence of periprosthetic fractures around the knee is increasing further because of an extended indication for knee replacement, previous revision arthroplasty, rising life expectancy and comorbidities. The relevance of local parameters such as malalignment, osseous defects, neighbouring implants, aseptic loosening and low-grade infections may sometimes be hidden behind the manifestation of a traumatic fracture. A differentiated diagnostic approach before the treatment of a periprosthetic fracture is of paramount importance, while the physician in-charge should also have particular expertise in fracture treatment and in advanced techniques of revision endoprosthetics. The following work gives an overview of this topic. Valid classifications are available for categorising periprosthetic fractures of the femur, the tibia and the patella respectively, which are helpful for the selection of treatment. With the wide-ranging modern treatment portfolio bearing in mind the substantial rate of complications and the heterogeneous functional outcome, the adequate analysis of fracture aetiology and the corresponding transformation into an individualised treatment concept offer the chance of an acceptable functional restoration of the patient at early full weight-bearing and prolonged implant survival. The management of complications is crucial to the final outcome.

  10. A Fracture Decoupling Experiment

    Science.gov (United States)

    Stroujkova, A. F.; Bonner, J. L.; Leidig, M.; Ferris, A. N.; Kim, W.; Carnevale, M.; Rath, T.; Lewkowicz, J.

    2012-12-01

    Multiple observations made at the Semipalatinsk Test Site suggest that conducting nuclear tests in the fracture zones left by previous explosions results in decreased seismic amplitudes for the second nuclear tests (or "repeat shots"). Decreased seismic amplitudes reduce both the probability of detection and the seismically estimated yield of a "repeat shot". In order to define the physical mechanism responsible for the amplitude reduction and to quantify the degree of the amplitude reduction in fractured rocks, Weston Geophysical Corp., in collaboration with Columbia University's Lamont Doherty Earth Observatory, conducted a multi-phase Fracture Decoupling Experiment (FDE) in central New Hampshire. The FDE involved conducting explosions of various yields in the damage/fracture zones of previously detonated explosions. In order to quantify rock damage after the blasts we performed well logging and seismic cross-hole tomography studies of the source region. Significant seismic velocity reduction was observed around the source regions after the initial explosions. Seismic waves produced by the explosions were recorded at near-source and local seismic networks, as well as several regional stations throughout northern New England. Our analysis confirms frequency dependent seismic amplitude reduction for the repeat shots compared to the explosions in un-fractured rocks. The amplitude reduction is caused by pore closing and/or by frictional losses within the fractured media.

  11. FRACTURING FLUID CHARACTERIZATION FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    Subhash Shah

    2000-08-01

    Hydraulic fracturing technology has been successfully applied for well stimulation of low and high permeability reservoirs for numerous years. Treatment optimization and improved economics have always been the key to the success and it is more so when the reservoirs under consideration are marginal. Fluids are widely used for the stimulation of wells. The Fracturing Fluid Characterization Facility (FFCF) has been established to provide the accurate prediction of the behavior of complex fracturing fluids under downhole conditions. The primary focus of the facility is to provide valuable insight into the various mechanisms that govern the flow of fracturing fluids and slurries through hydraulically created fractures. During the time between September 30, 1992, and March 31, 2000, the research efforts were devoted to the areas of fluid rheology, proppant transport, proppant flowback, dynamic fluid loss, perforation pressure losses, and frictional pressure losses. In this regard, a unique above-the-ground fracture simulator was designed and constructed at the FFCF, labeled ''The High Pressure Simulator'' (HPS). The FFCF is now available to industry for characterizing and understanding the behavior of complex fluid systems. To better reflect and encompass the broad spectrum of the petroleum industry, the FFCF now operates under a new name of ''The Well Construction Technology Center'' (WCTC). This report documents the summary of the activities performed during 1992-2000 at the FFCF.

  12. J/Ψ suppression

    International Nuclear Information System (INIS)

    Giubellino, P.; Abreu, M.C.; Alessandro, B.; Alexa, C.; Arnaldi, R.; Astruc, J.; Atayan, M.; Baglin, C.; Baldit, A.; Bedjidian, M.; Bellaiche, F.; Beole, S.; Boldea, V.; Bordalo, P.; Bussiere, A.; Capony, V.; Casagrande, L.; Castor, J.; Chambon, T.; Chaurand, B.; Chevrot, I.; Cheynis, B.; Chiavassa, E.; Cicalo, C.; Comets, M.P.; Constantinescu, S.; Cruz, J.; De Falco, A.; De Marco, N.; Dellacasa, G.; Devaux, A.; Dita, S.; Drapier, O.; Espagnon, B.; Fargeix, J.; Filippov, S.N.; Fleuret, F.; Force, P.; Gallio, M.; Gavrilov, Y.K.; Gerschel, C.; Giubellino, P.; Golubeva, M.B.; Gonin, M.; Grigorian, A.A.; Grossiord, J.Y.; Guber, F.F.; Guichard, A.; Gulkaninan, H.; Hakobyan, R.; Haroutunian, R.; Idzik, M.; Jouan, D.; Karavitcheva, T.L.; Kluberg, L.; Kurepin, A.B.; Le Bornec, Y.; Lourenco, C.; Mac Cormick, M.; Macciotta, P.; Marzari-Chiesa, A.; Masera, M.; Masoni, A.; Mehrabyan, S.; Mourgues, S.; Musso, A.; Ohlsson-Malek, F.; Petiau, P.; Piccotti, A.; Pizzi, J.R.; Prado da Silva, W.L.; Puddu, G.; Quintans, C.; Racca, C.; Ramello, L.; Ramos, S.; Rato-Mendes, P.; Riccati, L.; Romana, A.; Sartori, S.; Saturnini, P.; Scomparin, E.; Serci, S.; Shahoyan, R.; Silva, S.; Soave, C.; Sonderegger, P.; Tarrago, X.; Temnikov, P.; Topilskaya, N.S.; Usai, G.; Vale, C.; Vercellin, E.; Willis, N.

    1999-01-01

    The cross section for J/Ψ production in Pb-Pb interactions at 158 GeV per nucleon is measured at the CERN SPS by the NA50 experiment. The final results from the 1995 run are presented here together with preliminary ones from the high-statistics 1996 run. An anomalous J/Ψ suppression is observed in Pb-Pb collisions as compared to extrapolations of the previous results obtained by the NA38 experiment with proton and lighter ion beams. The results of the two runs are in good agreement. The results from the 1996 run allow the study of the onset of the anomalous suppression within the same set of data, showing evidence of a sharp change of behaviour around a value of neutral transverse energy, as measured by our electromagnetic calorimeter, of about 50 GeV

  13. Role of Lu and La in the intergranular films on growth of the prism surface in β-Si_3N_4: A molecular dynamics study

    International Nuclear Information System (INIS)

    Jiang, Yun; Garofalini, Stephen H.

    2016-01-01

    The different roles of Lu and La in the intergranular film in silicon nitride on the growth morphology are investigated via molecular dynamics simulations. While advanced microscopy shows each rare earth on the prism surface at room temperature, each additive affects the outward (perpendicular) growth of the surface differently. The simulations show the effect of elevated temperature on the adsorption of La and Lu on this surface that affects growth and provides the atomistic mechanism for the different growth morphology. - Graphical abstract: At elevated temperature, Lu ions move away from the surface as it grows, but remain in near contact (a-start, b-end), whereas La ions remain at the surface and prevent growth (c-start, d-end).

  14. Molecular dynamics simulations of the atomistic structure of the intergranular film between silicon nitride grains: Effect of composition, thickness, and surface vacancies

    International Nuclear Information System (INIS)

    Garofalini, Stephen H.

    2006-01-01

    Molecular dynamics computer simulations were used to study the atomistic structure of intergranular films (IGFs) between two basal oriented Si 3 N 4 crystals or between combined basal and prism oriented crystals. Ordering of the ions into the IGF induced by the crystal surfaces was observed using density profiles of the ions, although that ordering is effected by the roughness of the crystal surface. Density profiles of the sum of all ions misleadingly shows a rapid decay in the density oscillations and apparent ordering into the IGF. However, this is an artifact of the coincidence of the maximum in the peaks of one species with the minimum of another species and the actual oscillations of individual species extend into the IGF farther than the sum profile indicates. This result would have important implications regarding the density oscillations observed in physical experiments with regard to the actual extent of ordering into the IGF induced by the crystal surface

  15. Standard test method for determining the susceptibility to intergranular corrosion of 5XXX series Aluminum alloys by mass loss after exposure to nitric acid (NAMLT Test)

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 This test method describes a procedure for constant immersion intergranular corrosion testing of 5XXX series aluminum alloys. 1.2 This test method is applicable only to wrought products. 1.3 This test method covers type of specimen, specimen preparation, test environment, and method of exposure. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  16. Interfacial reactions in Ti-6Al-4V with laser-embedded SiC particles and the origin of intergranular corrosion susceptibility of an Al-Mg alloy

    NARCIS (Netherlands)

    Kooi, BJ; De Hosson, JTM; Carter, CB; Hall, EL; Nutt,; Briant, CL

    2000-01-01

    In the first part of the paper the microstructure of Ti-6Al-4V with laser embedded SiC particle is explained. The interfacial reaction between Ti and SiC is responsible for the largely improved wear resistance of the Ti alloy. In the second part the phase responsible for the intergranular corrosion

  17. Simulation of the high temperature intergranular strain hardening in fatigue of materials with hold time; Modelisation de l'ecrouissage intragranulaire en fatigue des metaux a haute temperature avec temps de maintien

    Energy Technology Data Exchange (ETDEWEB)

    Sauzay, M.; Mottot, M.; Noblecourt, M.; Allais, L.; Monnet, I.; Perinet, J

    2003-07-01

    This paper aims to simulate the behavior of some alloys in high temperature fatigue-relaxation (creep), for a long hold time (one month for each cycle) when laboratory experiments are difficult to realize. The first part presents an estimation of the internal intergranular stresses. The second part deals with the recovery occurring during the hold time. (A.L.B.)

  18. Effect of the microstructure on the sensibilization to intergranular corrosion of a 24. 7 Cr7. 4Ni duplex stainless steel. Efecto de la microestructura en la sensibilizacion a la corrosion inoxidable duplex 24, 7Cr7,Ni

    Energy Technology Data Exchange (ETDEWEB)

    Otero, E; Pardo, A; Merino, C; Hierro, P; Perez, F J

    1993-01-01

    The influence of microstructure on the resistance to intergranular corrosion of a 24.4Cr7.4Ni is studied. The results are discussed both in terms of the Huey experiment as well as of the sweeping corresponding to the experimental conditions under which the experiments have been performed. Author (11 refs.)

  19. Mitigation strategies of intergranular corrosion in systems of reactors of water boiling (BWR). Combined action of the chemistry of the hydrogen and the oxygen; Estrategias de mitigacion de la corrosion intergranular en sistemas de reactores de agua en ebullicion (BWR). Accion combinada de la quimica del hidrogeno y del oxigeno

    Energy Technology Data Exchange (ETDEWEB)

    Verdugo, M.

    2015-07-01

    Inter-Granular Stress Corrosion cracking (IGSCC) in austenitic stainless steel and in austenitic nickel-based alloys has been the subject of many studies the aim of which was to resolve one of the main problems faced by BWR nuclear power plants since the 1960s. This corrosion phenomenon is the result of the combined action of three factors: sensitization of the material, high local stresses and an aggressive medium. This paper deals with these factors separately and analyzes the oxidative chemistry of BWR reactors (aggressivity of the medium) as one the main causes if IGSCC. (Author)

  20. Coercivity enhancement of Nd–Fe–B sintered magnets with intergranular adding (Pr, Dy, Cu)−H{sub x} powders

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yujing; Ma, Tianyu, E-mail: maty@zju.edu.cn; Liu, Xiaolian; Liu, Pan; Jin, Jiaying; Zou, Junding; Yan, Mi, E-mail: mse_yanmi@zju.edu.cn

    2016-02-01

    Forming Nd{sub 2}Fe{sub 14}B/(Nd, Dy){sub 2}Fe{sub 14}B core–shell structure by intergranular adding Dy-containing sources into Nd–Fe–B sintered magnets is effective to improve coercivity and to minimize remanence loss simultaneously. However, the excessive Dy located in the intergranular regions has nearly no hard magnetic contribution, causing its low utilization efficiency. In this work, diluted Dy powders (Pr{sub 37}Dy{sub 30}Cu{sub 33})–H{sub x} were prepared and incorporated into Nd–Fe–B sintered magnets via a dual-alloy approach. The coercivity increases rapidly from 15.0 to 18.2 kOe by 21.3% with 2.0 wt% (Pr, Dy, Cu)–H{sub x} addition (the equivalent Dy is only 0.32 at%). The deduced coercivity incremental ratio is 10.0 kOe per unit Dy at%. Dehydrogenation reaction of (Pr, Dy, Cu)–H{sub x} occurs during sintering, which favors Dy diffusion towards the 2:14:1 phase grains as well as smoothing the grain boundaries (GBs). The enhanced local anisotropic field and the well decoupled 2:14:1 phase grains contribute to such rapid coercivity enhancement. This work suggests that adding diluted Dy hydrides is promising for fabricating high coercivity Nd–Fe–B sintered magnets with less heavy rare-earth consumption. - Highlights: • (Pr, Dy, Cu)–H{sub x} hydride powders were introduced into Nd–Fe–B sintered magnets. • Rapid coercivity enhancement from 15.0 kOe to 18.2 kOe with only 0.32 at% Dy was realized. • High utilization efficiency of Dy was achieved due to its promoted diffusion process. • Wettability and mobility of grain boundary phase was improved.

  1. Coercivity enhancement of Dy-free Nd–Fe–B sintered magnets by intergranular adding Ho{sub 63.4}Fe{sub 36.6} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Liping; Ma, Tianyu, E-mail: maty@zju.edu.cn; Wu, Chen; Zhang, Pei; Liu, Xiaolian; Yan, Mi, E-mail: mse_yanmi@zju.edu.cn

    2016-01-01

    High coercivity Nd–Fe–B sintered magnets serving in high-temperature environments always consume expensive and scarce heavy rare-earth Dy, which has simulated considerable interest to reduce Dy usage. In this work, coercivity of Dy-free magnets was investigated through intergranular adding eutectic Ho{sub 63.4}Fe{sub 36.6} powders. The coercivity increases gradually up to 4 wt% Ho{sub 63.4}Fe{sub 36.6} addition, however the remanence starts to deteriorate drastically as the addition is over 2.5 wt%. Coercivity above 18.0 kOe is obtained at the expense of a slight reduction in remanence through optimizing the addition amount and sintering conditions. The coercivity enhancement is explained through microstructural observations and elemental distribution analysis. (i) (Nd, Ho){sub 2}Fe{sub 14}B shell forms in the outer region of 2:14:1 phase grains, strengthening the local magnetic anisotropy filed, (ii) RE-rich grain boundary phase with low Fe content is thickened, weakening the magnetic coupling between adjacent 2:14:1 phase grains, and (iii) 2:14:1 phase grains are refined upon lowering sintering temperature, reducing the microstructural defects and the stray fields aroused from neighboring grains. - Highlights: • Eutectic Ho{sub 63.4}Fe{sub 36.6} powders were intergranular added to NdFeB sintered magnets. • The doped Dy-free magnet possessed coercivity of 18.0 kOe, remanence of 13.15 kGs. • (Nd, Ho){sub 2}Fe{sub 14}B shell formed in the surface of the matrix grains, increasing the H{sub A}. • Thick grain boundaries with low Fe content formed, decoupling the matrix grains. • By sintered at lower temperature, the matrix phase grains were refined.

  2. Fractures of the Jaw and Midface

    Science.gov (United States)

    ... switch to the Professional version Home Injuries and Poisoning Facial Injuries Fractures of the Jaw and Midface Symptoms Diagnosis Treatment Treatment of mandible fractures Treatment of maxillary fractures ...

  3. Experimental study upon the effect of irradiation on callus formation of fracture

    International Nuclear Information System (INIS)

    Saigusa, Fujio

    1981-01-01

    Irradiation effects on callus formation after bone fracture were studied in rats with fractured right lower extremity. Follow-up study was continued for 112 days since 3000 rad was irradiated to the fractured site 3 days after bone fracture. Callus formation was noted in both of the outer and inner part (bone marrow) of the diaphysis before 14 days after bone fracture, but it was slow and sparse compared with that of non-irradiated group. Callus formation tended to disappear gradually from the outside of the diaphysis after 28 days after bone fracture. Strong disturbance was found in the surrounding vascular system at this time. Inside of the diaphysis, callus formation was restricted the end of the fracture, where lamellar calluses fused together. Changes in vascular system remained until 56 days after bone fracture. Vascular distribution was most dense 28 days after bone fracture. In many of the calluses which have established fusion, findings suggested excessive calcification in the trabeculae. Vascular distribution at this time was sparse, vascular formation was markedly suppressed in the bone marrow, and very little vascular formation was found in the fractured edges of the bone. (Ueda, J.)

  4. Radiological classification of mandibular fractures

    International Nuclear Information System (INIS)

    Mihailova, H.

    2009-01-01

    Mandibular fractures present the biggest part (up to 97%) of the facial bone fractures. Method of choice for diagnosing of mandibular fractures is conventional radiography. The aim of the issue is to present an unified radiological classification of mandibular fractures for the clinical practice. This classification includes only those clinical symptoms of mandibular fracture which could be radiologically objectified: exact anatomical localization (F1-F6), teeth in fracture line (Ta,Tb), grade of dislocation (D I, D II), occlusal disturbances (O(+), O(-)). Radiological symptoms expressed by letter and number symbols are systematized in a formula - FTDO of mandibular fractures similar to TNM formula for tumours. FTDO formula expresses radiological diagnose of each mandibular fracture but it doesn't include neither the site (left or right) of the fracture, nor the kind and number of fractures. In order to express topography and number of fractures the radiological formula is transformed into a decimal fraction. The symbols (FTD) of right mandible fracture are written in the numerator and those of the left site - in the denominator. For double and multiple fractures between the symbols for each fracture we put '+'. Symbols for occlusal disturbances are put down opposite, the fractional line. So topographo-anatomical formula (FTD/FTD)xO is formed. In this way the whole radiological information for unilateral, bilateral, single or multiple fractures of the mandible is expressed. The information in the radiological topography anatomic formula, resp. from the unified topography-anatomic classification ensures a quick and exact X-ray diagnose of mandibular fracture. In this way contributes to get better, make easier and faster X-ray diagnostic process concerning mandibular fractures. And all these is a precondition for prevention of retardation of the diagnosis mandibular fracture. (author)

  5. Computer model for ductile fracture

    International Nuclear Information System (INIS)

    Moran, B.; Reaugh, J. E.

    1979-01-01

    A computer model is described for predicting ductile fracture initiation and propagation. The computer fracture model is calibrated by simple and notched round-bar tension tests and a precracked compact tension test. The model is used to predict fracture initiation and propagation in a Charpy specimen and compare the results with experiments. The calibrated model provides a correlation between Charpy V-notch (CVN) fracture energy and any measure of fracture toughness, such as J/sub Ic/. A second simpler empirical correlation was obtained using the energy to initiate fracture in the Charpy specimen rather than total energy CVN, and compared the results with the empirical correlation of Rolfe and Novak

  6. Polymer liquids fracture like solids

    DEFF Research Database (Denmark)

    Huang, Qian; Hassager, Ole

    2017-01-01

    While fracture in brittle solids has been studied for centuries until today, there are few studies on fracture in polymer liquids. Recent developments in experimental techniques, especially the combination of controlled filament stretching rheometry and high speed imaging, have opened new windows...... into the detailed study of fracture processes for polymer liquids. High speed imaging shows that polymer liquids fracture like solids with initiation and propagation of an edge fracture. However, remarkable features such as highly reproducible critical stress, independent appearance of multiple fractures...

  7. Management of penile fractures

    International Nuclear Information System (INIS)

    Ghilan, Abdulelah M. M.; Al-Asbahi, Waleed A.; Alwan, Mohammed A.; Al-Khanbashi, Omar M.; Ghafour, Mohammed A.

    2008-01-01

    Objective was to present our experience with surgical and conservative management of penile fracture. This prospective study was carried out in the Urology and Nephrology Center, at Al-Thawra General and Teaching Hospital, Sana'a, Yemen from June 2003 to September 2007 and included 30 patients presenting with penile fracture. Diagnosis was made clinically in all our patients. Six patients with simple fracture were treated conservatively while 24 patients with more severe injuries were operated upon. Patient's age ranged from 24-52 years (mean 31.3 years) 46.7% of patients were under the age of 30 years and 56.7% were unmarried. Hard manipulation of the erect penis for example during masturbation was the most frequent mechanism of fracture in 53.3% of patients. Solitary tear was found in 22 patients and bilateral corporal tears associated with urethral injury were found in 2 patients. Corporal tears were saturated with synthetic absorbable sutures and urethral injury was repaired primarily. All operated patients described full erection with straight penis except 3 of the 8 patients who were managed by direct longitudinal incision, in whom mild curvature during erection was observed. The conservatively treated patients described satisfactory penile straightness and erection. The optimal functional and cosmetic results are achieved following immediate surgical repair of penis fracture. Good results can also be obtained in some selected patients with conservative management. (author)

  8. Stress fractures in athletes

    International Nuclear Information System (INIS)

    Steingruber, I.E.; Wolf, C.; Gruber, H.; Czermak, B.V.; Mallouhi, A.; Jaschke, W.; Gabriel, M.

    2002-01-01

    Stress fractures may pose a diagnostic dilemma for radiologists since they are sometimes difficult to demonstrate on plain films and may simulate a tumour. They were first described in military personnel and professional athletes. Recently, there is an increasing incidence in the general population due to increasing sportive activities. Stress fractures occur most often in the lower extremities, especially in the tibia, the tarsal bone, the metatarsal bone, the femur and the fibula. In the upper extremities, they are commonly found in the humerus, the radius and the ulna. Some fractures of the lower extremities appear to be specific for particular sports, for example, fractures of the tibia affect mostly distance runners. Whereas stress fractures of the upper extremities are generally associated with upper limb-dominated sports. A correct diagnosis requires a careful clinical evaluation. The initial plain radiography may be normal. Further radiological evaluation could be performed by means of computerised tomography, magnetic resonance imaging and bone scanning. The latter two techniques are especially helpful for establishing a correct initial diagnosis. (orig.) [de

  9. The pressure suppression system

    International Nuclear Information System (INIS)

    Aust, E.

    1985-01-01

    Nuclear plants with boiling water reactors have a safety containment with a pressure suppression system (PSS). Proceeding on significant self-developments, today the three PSS-lines of General Electric Co. (GE), Kraftwerk Union AG (KWU) and ASEA-ATOM are predominant, which are currently represented by the MARK III type, the KWU type 72 and the BWR 75 containment. In addition, there are special developments for the nuclear ship propulsion and for the pressurized water reactors in the Soviet Union. Key design values of the PSS allow a first valuation of its loads during a hypothetical loss-of-coolant accident. (orig.) [de

  10. Transstyloid, transscaphoid, transcapitate fracture: a variant of scaphocapitate fractures.

    LENUS (Irish Health Repository)

    Burke, Neil G

    2014-01-01

    Transstyloid, transscaphoid, transcapitate fractures are uncommon. We report the case of a 28-year-old man who sustained this fracture following direct trauma. The patient was successfully treated by open reduction internal fixation of the scaphoid and proximal capitate fragment, with a good clinical outcome at 1-year follow-up. This pattern is a new variant of scaphocapitate fracture as involves a fracture of the radial styloid as well.

  11. DEM Particle Fracture Model

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Boning [Univ. of Colorado, Boulder, CO (United States); Herbold, Eric B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Homel, Michael A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Regueiro, Richard A. [Univ. of Colorado, Boulder, CO (United States)

    2015-12-01

    An adaptive particle fracture model in poly-ellipsoidal Discrete Element Method is developed. The poly-ellipsoidal particle will break into several sub-poly-ellipsoids by Hoek-Brown fracture criterion based on continuum stress and the maximum tensile stress in contacts. Also Weibull theory is introduced to consider the statistics and size effects on particle strength. Finally, high strain-rate split Hopkinson pressure bar experiment of silica sand is simulated using this newly developed model. Comparisons with experiments show that our particle fracture model can capture the mechanical behavior of this experiment very well, both in stress-strain response and particle size redistribution. The effects of density and packings o the samples are also studied in numerical examples.

  12. Fatigue stress fractures of the sacrum: diagnosis with MR imaging

    International Nuclear Information System (INIS)

    Ahovuo, J.A.; Vusuri, T.

    2004-01-01

    The aim of this study was to describe the MRI findings and clinical observations in a fatigue stress fracture of the sacrum. In this retrospective study, 380 conscripts (53 women, 327 men; age range 18-29 years, mean age 20.7 years) who suffered from stress-related hip pain were studied with MRI of the pelvis. The findings of MRI were evaluated with regard to stress fracture of the sacrum. Thirty-one (8%) patients had MRI changes in signal intensity of the cranial part of the sacrum, extending to the first and second sacral foramina. The MRI changes in signal intensity were intermediate on T1-weighted images, and high on short tau inversion recovery or T2-weighted fat-suppressed images. A linear signal void fracture line was also seen. Multiple stress injuries to the pelvic bones were also seen in 7 of 31 (23%) patients. Five patients (16%) had bilateral sacral stress fracture. Fatigue sacral stress fractures appeared more commonly in women than in men (p<0.001). During recovery time 20 of the 31 patients underwent control MRI, and fatty marrow conversion was seen in 8 (40%) cases as high signal intensity on T1-weighted images, which disappeared 5-6 months after the onset of symptoms. Fatigue sacral stress fractures are associated with stress-related hip pain. These fractures were more common in women than in men. Other stress injuries of the pelvis may be seen simultaneously with sacral stress fractures. Signal intensity of the sacrum was normal after 5-6 months

  13. [Distal clavicle fracture].

    Science.gov (United States)

    Seppel, G; Lenich, A; Imhoff, A B

    2014-06-01

    Reposition and fixation of unstable distal clavicle fractures with a low profile locking plate (Acumed, Hempshire, UK) in conjunction with a button/suture augmentation cerclage (DogBone/FibreTape, Arthrex, Naples, FL, USA). Unstable fractures of the distal clavicle (Jäger and Breitner IIA) in adults. Unstable fractures of the distal clavicle (Jäger and Breitner IV) in children. Distal clavicle fractures (Jäger and Breitner I, IIB or III) with marked dislocation, injury of nerves and vessels, or high functional demand. Patients in poor general condition. Fractures of the distal clavicle (Jäger and Breitner I, IIB or III) without marked dislocation or vertical instability. Local soft-tissue infection. Combination procedure: Initially the lateral part of the clavicle is exposed by a 4 cm skin incision. After reduction of the fracture, stabilization is performed with a low profile locking distal clavicle plate. Using a special guiding device, a transclavicular-transcoracoidal hole is drilled under arthroscopic view. Additional vertical stabilization is arthroscopically achieved by shuttling the DogBone/FibreTape cerclage from the lateral portal cranially through the clavicular plate. The two ends of the FibreTape cerclage are brought cranially via adjacent holes of the locking plate while the DogBone button is placed under the coracoid process. Thus, plate bridging is achieved. Finally reduction is performed and the cerclage is secured by surgical knotting. Use of an arm sling for 6 weeks. Due to the fact that the described technique is a relatively new procedure, long-term results are lacking. In the short term, patients postoperatively report high subjective satisfaction without persistent pain.

  14. Foal Fractures: Osteochondral Fragmentation, Proximal Sesamoid Bone Fractures/Sesamoiditis, and Distal Phalanx Fractures.

    Science.gov (United States)

    Reesink, Heidi L

    2017-08-01

    Foals are susceptible to many of the same types of fractures as adult horses, often secondary to external sources of trauma. In addition, some types of fractures are specific to foals and occur routinely in horses under 1 year of age. These foal-specific fractures may be due to the unique musculoskeletal properties of the developing animal and may present with distinct clinical signs. Treatment plans and prognoses are tailored specifically to young animals. Common fractures not affecting the long bones in foals are discussed in this article, including osteochondral fragmentation, proximal sesamoid bone fractures/sesamoiditis, and distal phalanx fractures. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Radiation effluent suppression system

    International Nuclear Information System (INIS)

    Watanabe, Atsushi.

    1992-01-01

    In a radiation release suppression system upon accident, an electromotive valve, a pneumatic operation valve or a manual operation valve is disposed to gas ventilation pipelines which are extended from both of a dry well and a wet well of a reactor container to a stuck. In addition, a combination filter of a metal fiber filter made of stainless steel etc. and an activated carbon fiber filter is disposed in the midway of pipelines in a reactor building. With such a constitution, the inside of the container can be depressurized (prevention of ruptures) and the amount of radioactive substances released to circumstances is remarkably suppressed by the effect of radioactive substance capturing effect of the metal fiber filter made of stainless steel etc. disposed in the vent pipe in the container and a radioactive substance capturing effect by the combination filter of the metal fiber filter made of stainless steel, etc. and the activated carbon fiber filter disposed in the gas ventilation pipelines even upon occurrence of an accident exceeding design basis. Systems can be simplified and minimized, and cost down can also be attained. (N.H.)

  16. Planck-suppressed operators

    International Nuclear Information System (INIS)

    Assassi, Valentin; Baumann, Daniel; Green, Daniel; McAllister, Liam

    2014-01-01

    We show that the recent Planck limits on primordial non-Gaussianity impose strong constraints on light hidden sector fields coupled to the inflaton via operators suppressed by a high mass scale Λ. We study a simple effective field theory in which a hidden sector field is coupled to a shift-symmetric inflaton via arbitrary operators up to dimension five. Self-interactions in the hidden sector lead to non-Gaussianity in the curvature perturbations. To be consistent with the Planck limit on local non-Gaussianity, the coupling to any hidden sector with light fields and natural cubic couplings must be suppressed by a very high scale Λ > 10 5 H. Even if the hidden sector has Gaussian correlations, nonlinearities in the mixing with the inflaton still lead to non-Gaussian curvature perturbations. In this case, the non-Gaussianity is of the equilateral or orthogonal type, and the Planck data requires Λ > 10 2 H

  17. Fractured Petroleum Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Firoozabadi, Dr. Abbas

    2000-01-18

    In this report the results of experiments of water injection in fractured porous media comprising a number of water-wet matrix blocks are reported for the first time. The blocks experience an advancing fracture-water level (FWL). Immersion-type experiments are performed for comparison; the dominant recovery mechanism changed from co-current to counter-current imbibition when the boundary conditions changed from advancing FWL to immersion-type. Single block experiments of co-current and counter-current imbibition was performed and co-current imbibition leads to more efficient recovery was found.

  18. Elastic plastic fracture mechanics

    International Nuclear Information System (INIS)

    Simpson, L.A.

    1978-07-01

    The application of linear elastic fracture mechanics (LEFM) to crack stability in brittle structures is now well understood and widely applied. However, in many structural materials, crack propagation is accompanied by considerable crack-tip plasticity which invalidates the use of LEFM. Thus, present day research in fracture mechanics is aimed at developing parameters for predicting crack propagation under elastic-plastic conditions. These include critical crack-opening-displacement methods, the J integral and R-curve techniques. This report provides an introduction to these concepts and gives some examples of their applications. (author)

  19. Dynamic fracture characterization of material

    International Nuclear Information System (INIS)

    Kobayashi, A.S.; Emery, A.F.; Liaw, B.M.

    1981-01-01

    The influences of a wide range of material properties, i.e. of A533B steel, a silicon nitride ceramic and a Homalite-100 photoelastic polymer, as well as the influences of the specimen sizes on the dynamic fracture response of fracture specimens are presented in this paper. The results of a numerical study show that the dynamic fracture responses of these fracture specimens of proportional dimensions were indistinguishable provided the normalized dynamic fracture toughness versus normalized crack velocity relations of the three materials coincide. The limited results suggest that should the normalized dynamic fracture toughness versus normalized crack velocity relations between prototype and model materials coincide, then dynamic fracture experiments on scaled models can be used to infer the dynamic fracture response of the prototype. (orig./HP)

  20. Fracture surfaces of granular pastes.

    Science.gov (United States)

    Mohamed Abdelhaye, Y O; Chaouche, M; Van Damme, H

    2013-11-01

    Granular pastes are dense dispersions of non-colloidal grains in a simple or a complex fluid. Typical examples are the coating, gluing or sealing mortars used in building applications. We study the cohesive rupture of thick mortar layers in a simple pulling test where the paste is initially confined between two flat surfaces. After hardening, the morphology of the fracture surfaces was investigated, using either the box counting method to analyze fracture profiles perpendicular to the mean fracture plane, or the slit-island method to analyze the islands obtained by cutting the fracture surfaces at different heights, parallel to the mean fracture plane. The fracture surfaces were shown to exhibit scaling properties over several decades. However, contrary to what has been observed in the brittle or ductile fracture of solid materials, the islands were shown to be mass fractals. This was related to the extensive plastic flow involved in the fracture process.

  1. Flexible fixation and fracture healing

    DEFF Research Database (Denmark)

    Schmal, Hagen; Strohm, Peter C; Jaeger, Martin

    2011-01-01

    , noncomminuted fractures. External fixation uses external bars for stabilization, whereas internal fixation is realized by subcutaneous placement of locking plates. Both of these "biologic" osteosynthesis methods allow a minimally invasive approach and do not compromise fracture hematoma and periosteal blood...

  2. Gene Therapy for Fracture Repair

    National Research Council Canada - National Science Library

    Lau, William

    2005-01-01

    .... We have identified a murine leukemia virus (MLV) vector that provides robust transgene expression in fracture tissues, and applied it to the rat femur fracture model to express therapeutic transgenes...

  3. Correlation of Hip Fracture with Other Fracture Types: Toward a Rational Composite Hip Fracture Endpoint

    Science.gov (United States)

    Colón-Emeric, Cathleen; Pieper, Carl F.; Grubber, Janet; Van Scoyoc, Lynn; Schnell, Merritt L; Van Houtven, Courtney Harold; Pearson, Megan; Lafleur, Joanne; Lyles, Kenneth W.; Adler, Robert A.

    2016-01-01

    Purpose With ethical requirements to the enrollment of lower risk subjects, osteoporosis trials are underpowered to detect reduction in hip fractures. Different skeletal sites have different levels of fracture risk and response to treatment. We sought to identify fracture sites which cluster with hip fracture at higher than expected frequency; if these sites respond to treatment similarly, then a composite fracture endpoint could provide a better estimate of hip fracture reduction. Methods Cohort study using Veterans Affairs and Medicare administrative data. Male Veterans (n=5,036,536) aged 50-99 years receiving VA primary care between1999-2009 were included. Fractures were ascertained using ICD9 and CPT codes and classified by skeletal site. Pearson correlation coefficients, logistic regression and kappa statistics, were used to describe the correlation between each fracture type and hip fracture within individuals, without regards to the timing of the events. Results 595,579 (11.8%) men suffered 1 or more fractures and 179,597 (3.6%) suffered 2 or more fractures during the time under study. Of those with one or more fractures, rib was the most common site (29%), followed by spine (22%), hip (21%) and femur (20%). The fracture types most highly correlated with hip fracture were pelvic/acetabular (Pearson correlation coefficient 0.25, p<0.0001), femur (0.15, p<0.0001), and shoulder (0.11, p<0.0001). Conclusions Pelvic, acetabular, femur, and shoulder fractures cluster with hip fractures within individuals at greater than expected frequency. If we observe similar treatment risk reductions within that cluster, subsequent trials could consider use of a composite endpoint to better estimate hip fracture risk. PMID:26151123

  4. Statistics and thermodynamics of fracture

    Science.gov (United States)

    Chudnovsky, A.

    1984-01-01

    A probabilistic model of the fracture processes unifying the phenomenological study of long term strength of materials, fracture mechanics and statistical approaches to fracture is briefly outlined. The general framework of irreversible thermodynamics is employed to model the deterministic side of the failure phenomenon. The stochastic calculus is used to account for thg failure mechanisms controlled by chance; particularly, the random roughness of fracture surfaces.

  5. Complications in ankle fracture surgery

    OpenAIRE

    Ovaska, Mikko

    2015-01-01

    Mikko Ovaska. Complications in Ankle Fracture Surgery. Helsinki Bone and Joint Research Group, Department of Orthopaedic Surgery and Traumatology, Faculty of Medicine, University of Helsinki, Finland. Helsinki 2014. Ankle fractures are among the most frequently encountered surgically treated fractures. The operative treatment of this fracture may be associated with several complications. The most frequently encountered complications are related wound healing, and deep infection may have d...

  6. Management of osteoporotic vertebral fractures

    OpenAIRE

    Dionyssiotis, Yannis

    2010-01-01

    Yannis DionyssiotisRhodes General Hospital, Rhodes, GreeceAbstract: Osteoporotic vertebral fractures are associated with considerable reduction of quality of life, morbidity, and mortality. The management of patients with vertebral fractures should include treatment for osteoporosis and measures to reduce pain and improve mobility. This article provides information for management and rehabilitation of vertebral fractures based on clinical experience and literature.Keywords: vertebral fracture...

  7. Osteoporotic Hip and Spine Fractures

    OpenAIRE

    Cannada, Lisa K.; Hill, Brian W.

    2014-01-01

    Hip and spine fractures represent just a portion of the burden of osteoporosis; however, these fractures require treatment and often represent a major change in lifestyle for the patient and their family. The orthopedic surgeon plays a crucial role, not only in the treatment of these injuries but also providing guidance in prevention of future osteoporotic fractures. This review provides a brief epidemiology of the fractures, details the surgical techniques, and outlines the current treatment...

  8. Some probabilistic aspects of fracture

    International Nuclear Information System (INIS)

    Thomas, J.M.

    1982-01-01

    Some probabilistic aspects of fracture in structural and mechanical components are examined. The principles of fracture mechanics, material quality and inspection uncertainty are formulated into a conceptual and analytical framework for prediction of failure probability. The role of probabilistic fracture mechanics in a more global context of risk and optimization of decisions is illustrated. An example, where Monte Carlo simulation was used to implement a probabilistic fracture mechanics analysis, is discussed. (orig.)

  9. Oxygen suppression in boiling water reactors. Phase 2. Annual report 1981, December 2, 1980-December 31, 1981

    International Nuclear Information System (INIS)

    Burley, E.L.

    1982-07-01

    A hydrogen addition test will be performed in the Dresden-2 reactor of Commonwealth Edison Company during 1982. Up to 2 ppM hydrogen will be added to and dissolved in the reactor feedwater to reverse the radiolysis reaction in the reactor core and suppress oxgen concentration in the primary coolant. At low oxygen levels the propensity of stressed and sensitized 304 stainless steel toward intergranular stress corrosion cracking is greatly reduced. The test will answer outstanding questions and uncertainties in the areas of water chemistry, equipment design and materials performance. Nine special sample facilities will be prepared in the primary coolant, main stream, feedwater/condensate, and offgas systems. Instrumentation will be available to measure hydrogen, oxygen, conductivity, pH, soluble and insoluble corrosion products, and electrochemical potentials. In addition, an autoclave in which confirming constant extension rate tests can be conducted in reactor water will be provided

  10. Hydrologic behavior of fracture networks

    International Nuclear Information System (INIS)

    Long, J.C.S.; Endo, H.K.; Karasaki, K.; Pyrak, L.; MacLean, P.; Witherspoon, P.A.

    1985-01-01

    This paper reviews recent research on the nature of flow and transport in discontinuous fracture networks. The hydrologic behavior of these networks has been examined using two- and three-dimensional numerical models. The numerical models represent random realizations of fracture networks based on statistical field measurements of fracture geometry and equivalent hydraulic aperture. The authors have compared the flux and mechanical transported behavior of these networks to the behavior of equivalent continua. In this way they were able to determine whether a given fracture network could be modeled as an equivalent porous media in both flux and advective transport studies. They have examined departures from porous media behavior both as a function of interconnectivity and heterogeneity. Parameter studies have revealed behavior patterns such as: given a fracture frequency that can be measured in the field, porous media like behavior and the magnitude of permeability are both enhanced if the fractures are longer and the standard deviation of fracture permeabilities is smaller. The behavior of well tests in fractured networks has been modeled and compared to a new analytical well test solution which accounts for the early time dominance of the fractures intersecting the well. Finally, a three-dimensional fracture flow model has been constructed which assumes fractures are randomly located discs. This model has been constructed which assumes fractures are randomly located discs. This model uses a semi-analytical solution for flow such that it is relatively easy to use the model as a tool for stochastic analysis. 13 references, 12 figures

  11. CT evaluation of acetabular fractures

    Energy Technology Data Exchange (ETDEWEB)

    Piazza, P; Girelli, G; Coran, F; Lutman, M

    1986-01-01

    The paper deals with sixteen cases of acetabular fractures studied with CT. After a short description of the normal CT findings, the different kind of fractures are reported. The usefulness of CT examination in evaluating acetabular fractures and their complications is confirmed both in conservative treatment and surgical approach.

  12. Fracture of the occipital condyle

    International Nuclear Information System (INIS)

    Wessels, L.S.

    1990-01-01

    The term fracture of the occipital condyle is a misnomer and and usually represents an extensive fracture of the posterior fossa skull base extending onto the squamous portion of the occipital bone and even further forward. These fractures should be suspected when the lower cranial nerves are affected after severe cranial trauma. Conservative management appears to be indicated. 2 figs., 5 refs

  13. Pediatric maxillary fractures.

    Science.gov (United States)

    Yu, Jack; Dinsmore, Robert; Mar, Philip; Bhatt, Kirit

    2011-07-01

    Pediatric craniofacial structures differ from those of adults in many ways. Because of these differences, management of pediatric craniofacial fractures is not the same as those in adults. The most important differences that have clinical relevance are the mechanical properties, craniofacial anatomy, healing capacity, and dental morphology. This article will review these key differences and the management of pediatric maxillary fractures. From the mechanical properties' perspective, pediatric bones are much more resilient than adult bones; as such, they undergo plastic deformation and ductile failure. From the gross anatomic perspective, the relative proportion of the cranial to facial structures is much larger for the pediatric patients and the sinuses are not yet developed. The differences related to dentition and dental development are more conical crowns, larger interdental spaces, and presence of permanent tooth buds in the pediatric population. The fracture pattern, as a result of all the above, does not follow the classic Le Fort types. The maxillomandibular fixation may require circum-mandibular wires, drop wires, or Ivy loops. Interfragmentary ligatures using absorbable sutures play a much greater role in these patients. The use of plates and screws should take into consideration the future development with respect to growth centers and the location of the permanent tooth buds. Pediatric maxillary fractures are not common, require different treatments, and enjoy better long-term outcomes.

  14. Fracture Mechanics of Concrete

    DEFF Research Database (Denmark)

    Ulfkjær, Jens Peder

    Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high-strength......Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high......-strength concrete. Chapter 2 A description of the factors which influence the strength and cracking of concrete and high strength concrete is made. Then basic linear fracture mechanics is outlined followed by a description and evaluation of the models used to describe concrete fracture in tension. The chapter ends...... and the goveming equations are explicit and simple. These properties of the model make it a very powerful tool, which is applicable for the designing engineer. The method is also extended to reinforced concrete, where the results look very promising. The large experimental investigation on high-strength concrete...

  15. Fracture mechanics and microstructures

    International Nuclear Information System (INIS)

    Gee, M.G.; Morrell, R.

    1986-01-01

    The influence of microstructure on defects in ceramics, and the consequences of their presence for the application of fracture mechanics theories are reviewed. The complexities of microstructures, especially the multiphase nature, the crystallographic anisotropy and the resultant anisotropic physical properties, and the variation of microstructure and surface finish from point to point in real components, all lead to considerable uncertainties in the actual performance of any particular component. It is concluded that although the concepts of fracture mechanics have been and will continue to be most useful for the qualitative explanation of fracture phenomena, the usefulness as a predictive tool with respect to most existing types of material is limited by the interrelation between material microstructure and mechanical properties. At present, the only method of eliminating components with unsatisfactory mechanical properties is to proof-test them, despite the fact that proof-testing itself is limited in ability to cope with changes to the component in service. The aim of the manufacturer must be to improve quality and consistency within individual components, from component to component, and from batch to batch. The aim of the fracture specialist must be to study longer-term properties to improve the accuracy of behaviour predictions with a stronger data base. Materials development needs to concentrate on obtaining defect-free materials that can be translated into more-reliable products, using our present understanding of the influence of microstructure on strength and toughness

  16. Fractal description of fractures

    International Nuclear Information System (INIS)

    Lung, C.W.

    1991-06-01

    Recent studies on the fractal description of fractures are reviewed. Some problems on this subject are discussed. It seems hopeful to use the fractal dimension as a parameter for quantitative fractography and to apply fractal structures to the development of high toughness materials. (author). 28 refs, 7 figs

  17. Fracture Mechanics of Concrete

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    the international workshop on concrete fracture, organised by A Carpinteri, at Torino ... The next question is how to bring the size effect into codes of practice on the ... analysis of the recent collapse of the World Trade Center in New York by Z P ...

  18. Oblique Axis Body Fracture

    DEFF Research Database (Denmark)

    Takai, Hirokazu; Konstantinidis, Lukas; Schmal, Hagen

    2016-01-01

    type" fracture pattern. The first patient was treated conservatively with cervical spine immobilization in a semirigid collar. However, gross displacement was noted at the 6-week follow-up visit. The second patient was therefore treated operatively by C1-C3/4 posterior fusion and the course...... for this injury and suggest early operative stabilization....

  19. Proximal femoral fractures

    DEFF Research Database (Denmark)

    Palm, Henrik; Teixidor, Jordi

    2015-01-01

    searched the homepages of the national heath authorities and national orthopedic societies in West Europe and found 11 national or regional (in case of no national) guidelines including any type of proximal femoral fracture surgery. RESULTS: Pathway consensus is outspread (internal fixation for un...

  20. Fracture mechanics and parapsychology

    Science.gov (United States)

    Cherepanov, G. P.

    2010-08-01

    The problem of postcritical deformation of materials beyond the ultimate strength is considered a division of fracture mechanics. A simple example is used to show the relationship between this problem and parapsychology, which studies phenomena and processes where the causality principle fails. It is shown that the concept of postcritical deformation leads to problems with no solution

  1. Metatarsal fracture (acute) - aftercare

    Science.gov (United States)

    ... of your 5th metatarsal bone closest to the ankle is called a Jones fracture. This area of the bone has low blood ... Swelling, pain, numbness, or tingling in your leg, ankle, or foot that becomes worse Your leg or foot turns purple Fever

  2. Flow characteristics through a single fracture of artificial fracture system

    International Nuclear Information System (INIS)

    Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Jeon, Seok Won

    2001-04-01

    Fracture flow in rock masses is one of the most important issues in petroleum engineering, geology, and hydrogeology. Especially, in case of the HLW disposal, groundwater flow in fractures is an important factor in the performance assessment of the repository because the radionuclides move along the flowing groundwater through fractures. Recently, the characterization of fractures and the modeling of fluid flow in fractures are studied by a great number of researchers. Among those studies, the hydraulic behavior in a single fracture is one of the basic issues for understanding of fracture flow in rockmass. In this study, a fluid flow test in the single fracture made of transparent epoxy replica was carried out to obtain the practical exponent values proposed from the Cubic law and to estimate the flow rates through a single fracture. Not only the relationship between flow rates and the geometry of fracture was studied, but also the various statistical parameters of fracture geometry were compared to the effective transmissivity data obtained from computer simulation.

  3. Distinguishing stress fractures from pathologic fractures: a multimodality approach

    International Nuclear Information System (INIS)

    Fayad, Laura M.; Kamel, Ihab R.; Kawamoto, Satomi; Bluemke, David A.; Fishman, Elliot K.; Frassica, Frank J.

    2005-01-01

    Whereas stress fractures occur in normal or metabolically weakened bones, pathologic fractures occur at the site of a bone tumor. Unfortunately, stress fractures may share imaging features with pathologic fractures on plain radiography, and therefore other modalities are commonly utilized to distinguish these entities. Additional cross-sectional imaging with CT or MRI as well as scintigraphy and PET scanning is often performed for further evaluation. For the detailed assessment of a fracture site, CT offers a high-resolution view of the bone cortex and periosteum which aids the diagnosis of a pathologic fracture. The character of underlying bone marrow patterns of destruction can also be ascertained along with evidence of a soft tissue mass. MRI, however, is a more sensitive technique for the detection of underlying bone marrow lesions at a fracture site. In addition, the surrounding soft tissues, including possible involvement of adjacent muscle, can be well evaluated with MRI. While bone scintigraphy and FDG-PET are not specific, they offer a whole-body screen for metastases in the case of a suspected malignant pathologic fracture. In this review, we present select examples of fractures that underscore imaging features that help distinguish stress fractures from pathologic fractures, since accurate differentiation of these entities is paramount. (orig.)

  4. Cough-induced rib fractures.

    Science.gov (United States)

    Hanak, Viktor; Hartman, Thomas E; Ryu, Jay H

    2005-07-01

    To define the demographic, clinical, and radiological features of patients with cough-induced rib fractures and to assess potential risk factors. For this retrospective, single-center study, we identified all cases of cough-induced rib fractures diagnosed at the Mayo Clinic in Rochester, Minn, over a 9-year period between January 1, 1996, and January 31, 2005. Bone densitometry data from patients' medical records were analyzed, and T scores were used to classify patients into bone density categories. The mean +/- SD age of the 54 study patients at presentation was 55+/-17 years, and 42 patients (78%) were female. Patients presented with chest wall pain after onset of cough. Rib fracture was associated with chronic cough (> or =3 weeks' duration) in 85% of patients. Rib fractures were documented by chest radiography, rib radiography, computed tomography, or bone scan. Chest radiography had been performed in 52 patients and revealed rib fracture in 30 (58%). There were 112 fractured ribs in 54 patients. One half of patients had more than one fractured rib. Right-sided rib fractures alone were present in 17 patients (26 fractured ribs), left-sided in 23 patients (35 fractured ribs), and bilateral in 14 patients (51 fractured ribs). The most commonly fractured rib on both sides was rib 6. The fractures were most common at the lateral aspect of the rib cage. Bone densitometry was done in 26 patients and revealed osteopenia or osteoporosis in 17 (65%). Cough-induced rib fractures occur primarily in women with chronic cough. Middle ribs along the lateral aspect of the rib cage are affected most commonly. Although reduced bone density is likely a risk factor, cough-induced rib fractures can occur in the presence of normal bone density.

  5. Sealing of rock fractures

    International Nuclear Information System (INIS)

    Pusch, R.; Erlstroem, M.; Boergesson, L.

    1985-12-01

    The major water-bearing fractures in granite usually from fairly regular sets but the extension and degree of connectivity is varying. This means that only a few fractures that are interconnected with the deposition holes and larger water-bearing structures in a HLW repository are expected and if they can be identified and cut off through sealing it would be possible to improve the isolation of waste packages very effectively. Nature's own fracture sealing mechanisms may be simulated and a survey of the involved processes actually suggests a number of possible filling methods and substances. Most of them require high temperature and pressure and correspondingly sophisticated techniques, but some are of potential interest for immediate application with rather moderate effort. Such a technique is to fill the fractures with clayey substances which stay flexible and low-permeable provided that they remain physically and chemically intact. It is demonstrated in the report that effective grouting requires a very low viscosity and shear strength of the substance and this can be achieved by mechanical agitation as demonstrated in this report. Thus, by superimposing static pressure and shear waves induced by percussion hammering at a suitable frequency, clays and fine-grained silts as well as cement can be driven into fractures with an average aperture as small as 0.1 mm. Experiments were made in the laboratory using concrete and steel plates, and a field pilot test was also conducted under realistic conditions on site in Stripa. They all demonstrated the practicality of the 'dynamic injection technique' and that the fluid condition of the grouts yielded complete filling of the injected space to a considerable distance from the injection point. The field test indicated a good sealing ability as well as a surprisingly high resistance to erosion and piping. (author)

  6. In situ observations of oxide fracture on austenitic stainless steels relevant to IASCC

    International Nuclear Information System (INIS)

    Duff, J.; Burke, M.G.; Scenini, F.

    2015-01-01

    Stress Corrosion Cracking (SCC) and Irradiation-Assisted Stress Corrosion Cracking (IASCC) are important failure modes in the nuclear industry, yet the exact mechanism(s) responsible for these complex failure phenomena are not fully understood. In particular, considerable attention is being focused on SCC and IASCC initiation and the behaviour of the oxidised metal surface during straining in a relevant environment. Experimental observations and data for oxide fracture at the grain boundary are limited, but are also required for the development of crack growth models. In this work, the role of strain localization on surface oxide fracture has been examined via: 1) in situ straining experiments using a state-of-the-art imaging autoclave; and 2) ex situ studies using pre-oxidised samples in a FEG-SEM with a micro-tensile stage. The work was conducted using three materials: 1) a non-irradiated archive Type 316 Stainless Steel, 2) a 1 dpa proton-irradiated Type 316 Stainless Steel, and 3) a model alloy designed to simulate the grain boundary composition resulting from radiation induced segregation. The observations were performed on samples pre-oxidized at 320 C. degrees in high purity, water containing 30 cm 3 /kg of dissolved H 2 and 2 ppm Li additions. The samples were strained in tension and the surface deformation measured via Digital Image Correlation. This technique provided quantitative data regarding the intergranular strains associated with oxide fracture. Oxide fracture and strain development were also related to the local irradiation-induced microstructure and grain boundary character. The results from this work contribute to the mechanistic information on the role of strain localization and composition on the incubation stages of IASCC. (authors)

  7. Mechanical behavior and fracture characterization of the T91 martensitic steel in liquid sodium environment

    International Nuclear Information System (INIS)

    Hamdane, Ouadie

    2012-01-01

    The T91 martensitic steel is designed to constitute structural material of future sodium fast reactors of fourth generation, where it will be subjected to stresses in presence of liquid sodium. This study presents a qualitative and quantitative estimate of the sensitivity of T91 steel towards the phenomenon of liquid metal embrittlement. The effect of liquid sodium on T91 steel was studied and quantified according to the temperature and the cross head rate displacement, by using a set-up of Small Punch Test, three and four bending test, developed in laboratory. Mechanical tests in sodium environment are carried out inside a Plexiglas cell, conceived and developed at the laboratory. The atmosphere inside this cell is severely purified and controlled, in order to avoid on the one hand an explosive reaction of sodium with moisture, or an ignition with oxygen, and on the other hand to minimize the presence of impurities in liquid sodium used. The presence of sodium accelerates T91 steel fracture at low temperature, without modifying its ductile character. The T91 pre-immersion in sodium makes it possible to dissolve the protective layer of chromium oxide, and to obtain an intimate contact with the molten metal. However, pre-immersion generates a surface defects which cause a partial embrittlement by sodium. The hardening of T91 steel by heat treatment with a tempering temperature of 550 C (T91-TR550) causes a total embrittlement of steel in presence of sodium, with and without pre-immersion. The rupture of the T91-TR550 steel takes then place by intergranular de-cohesion, corresponding to the crack initiation phase, followed by laths de-cohesion, corresponding to the phase of propagation of these cracks. The mechanism suggested in this study is based on the intergranular penetration of sodium, supported by the presence of segregated impurities such phosphorus, and by the plastic deformation [fr

  8. Social inequality and hip fracture

    DEFF Research Database (Denmark)

    Harvey, N. C.; Hansen, L.; Judge, A.

    2015-01-01

    Social inequality appears to be increasing in many countries. We explored whether risk of hip fracture was associated with markers of inequality and whether these relationships changed with time, using data from Danish Health Registries. Methods: All patients 60 years or older with a primary hip...... fracture (ICD10: S720, S721, S722 and S729) were identified from 1 January 1995 to 31 December 2011. Hip fracture patients were matched 1:1 on age, gender and year of fracture to a non-hip fracture control. An individual's education attainment was defined as basic, secondary or higher, and their income...

  9. Seismic characterization of fracture properties

    International Nuclear Information System (INIS)

    Myer, L.R.; Hopkins, D.; Cook, N.G.W.; Pyrak-Nolte, L.J.

    1990-01-01

    The purpose of this paper is to show that there is a relationship, both empirical and theoretical, between the measured seismic response, the mechanical stiffness (also referred to as specific stiffness) of fractures and their hydraulic conductivity. Laboratory measurements of the mechanical stiffness, hydraulic conductivity and seismic properties of natural fractures are summarized. A theoretical model for the amplitude and group time delay for compressional and shear waves transmitted across a single fracture is presented. Predictions based on this model are compared with laboratory measurements. Finally, the results for a single fracture are extended to multiple parallel fractures. 13 refs., 6 figs

  10. Screening for suppression in young children: the Polaroid Suppression test

    NARCIS (Netherlands)

    Pott, J.W.R.; Oosterveen, DK; Van Hof-van Duin, J

    1998-01-01

    Background: Assessment of monocular visual impairment during screening of young children is often hampered by lack of cooperation. Because strabismus, amblyopia, or anisometropia may lead to monocular suppression during binocular viewing conditions, a test was developed to screen far suppression in

  11. Pubic insufficiency fracture: MRI findings

    International Nuclear Information System (INIS)

    Min, Tae Kyu; Lee, Yeon Soo; Park, Jeong Mi; Kim, Jee Young; Chung, Hong Jun; Lee, Eun Hee; Lee, Eun Ja; Kang, So Won; Han Tae Il

    2000-01-01

    To evaluate the characteristic MRI findings of pubic insufficiency fracture. In nine cases of pubic insufficiency fracture, the findings of plain radiography (n=9), MRI (n=9), and bone scintigraphy (n=8) were reviewed. We retrospectively analyzed, with regard to fracture site, the destructive pattern revealed by plain radiography, and uptake by other pelvic bones, as demonstrated by RI bone scanning. The MR findings evaluated were the fracture gap and its signal intensity, the site and signal intensity of the soft tissue mass, and other pelvic bone fractures. Plain radiography revealed osteolysis and sclerosis of pubic bone in eight of nine cases (89%), and parasymphyseal fractures in seven (78%). RI indicated uptake by the sacrum in six cases (66%), and by the ilium in three (33%). MR findings of fracture gap (seven cases, 78%) were hypo to isointensity on T1WI, hyper intensity on T2WI and the absence of contrast enhancement. Soft tissue masses were found in seven cases (78%); in four of these the location was parasymphyseal, and in three, surrounding muscle was involved. Hypo to isointensity was revealed by T1WI, hyperintensity by T2WI, and there was peripheral enhancement. Other associated pelvic bone fractures involved the sacrum in seven cases and the ilium in four. The characteristic MR findings of pubic insufficiency fracture were parasymphyseal location, fracture gap, peripherally enhanced soft tissue mass formation, and fractures of other pelvic bones, namely the sacrum and ilium

  12. Influences of process parameters and microstructure on the fracture mechanisms of ODS steels

    International Nuclear Information System (INIS)

    Rouffié, A.L.; Wident, P.; Ziolek, L.; Delabrouille, F.; Tanguy, B.; Crépin, J.; Pineau, A.; Garat, V.; Fournier, B.

    2013-01-01

    The present work investigates the impact response of three ODS steels containing 9%Cr and 14%Cr. These steels were produced by hot extrusion in the shapes of a rod and a plate. The 9%Cr ODS steel has a quasi-isotropic microstructure and is given as a reference material. In comparison, the 14%Cr ODS steel has a strong morphological and crystallographic texture given by the process route. The impact behaviour is anisotropic and the fracture energies are higher when the material is tested in the longitudinal direction compared to the transverse direction. Moreover, the 14%Cr ODS steel has a better impact behaviour when it is extruded in the shape of a rod rather than in the shape of a plate. This work focuses on the fracture mechanisms involved in the ductile to brittle transition regime and in the brittle regime of these materials. In the case of the 14%Cr ODS steel, the cleavage facets observed at very low temperature are much larger than the actual size of the grains. Packets of grains with less than 15° of internal misorientation were defined as effective grains for cleavage. In the transition range, the texture enhances intergranular delamination on the 14%Cr rod material. The occurrence of delamination consumes a lot of energy and tends to enhance scattering in impact energies

  13. Influences of process parameters and microstructure on the fracture mechanisms of ODS steels

    Energy Technology Data Exchange (ETDEWEB)

    Rouffié, A.L., E-mail: anne-laure.rouffie@cea.fr [CEA, DEN, DANS, DMN, SRMA, Bât 453, F-91191 Gif-sur-Yvette (France); Wident, P.; Ziolek, L. [CEA, DEN, DANS, DMN, SRMA, Bât 453, F-91191 Gif-sur-Yvette (France); Delabrouille, F. [EDF – EDF R and D, Département MMC groupe Métallurgie, 77818 Moret sur Loing (France); Tanguy, B. [CEA, DEN, DANS, DMN, SEMI, Bât 625, F-91191 Gif-sur-Yvette (France); Crépin, J.; Pineau, A. [Mines ParisTech, Centre des Matériaux PM Fourt, UMR CNRS 7633, BP 87, 91003 Evry (France); Garat, V. [AREVA NP, 10 rue J. Récamier, 69006 Lyon (France); Fournier, B. [Manoir Industries, Metallurgy Dept., 12 rue des Ardennes, BP 8401 Pîtres, 27108 Val de Reuil Cedex (France)

    2013-02-15

    The present work investigates the impact response of three ODS steels containing 9%Cr and 14%Cr. These steels were produced by hot extrusion in the shapes of a rod and a plate. The 9%Cr ODS steel has a quasi-isotropic microstructure and is given as a reference material. In comparison, the 14%Cr ODS steel has a strong morphological and crystallographic texture given by the process route. The impact behaviour is anisotropic and the fracture energies are higher when the material is tested in the longitudinal direction compared to the transverse direction. Moreover, the 14%Cr ODS steel has a better impact behaviour when it is extruded in the shape of a rod rather than in the shape of a plate. This work focuses on the fracture mechanisms involved in the ductile to brittle transition regime and in the brittle regime of these materials. In the case of the 14%Cr ODS steel, the cleavage facets observed at very low temperature are much larger than the actual size of the grains. Packets of grains with less than 15° of internal misorientation were defined as effective grains for cleavage. In the transition range, the texture enhances intergranular delamination on the 14%Cr rod material. The occurrence of delamination consumes a lot of energy and tends to enhance scattering in impact energies.

  14. Hydraulic fracture propagation modeling and data-based fracture identification

    Science.gov (United States)

    Zhou, Jing

    Successful shale gas and tight oil production is enabled by the engineering innovation of horizontal drilling and hydraulic fracturing. Hydraulically induced fractures will most likely deviate from the bi-wing planar pattern and generate complex fracture networks due to mechanical interactions and reservoir heterogeneity, both of which render the conventional fracture simulators insufficient to characterize the fractured reservoir. Moreover, in reservoirs with ultra-low permeability, the natural fractures are widely distributed, which will result in hydraulic fractures branching and merging at the interface and consequently lead to the creation of more complex fracture networks. Thus, developing a reliable hydraulic fracturing simulator, including both mechanical interaction and fluid flow, is critical in maximizing hydrocarbon recovery and optimizing fracture/well design and completion strategy in multistage horizontal wells. A novel fully coupled reservoir flow and geomechanics model based on the dual-lattice system is developed to simulate multiple nonplanar fractures' propagation in both homogeneous and heterogeneous reservoirs with or without pre-existing natural fractures. Initiation, growth, and coalescence of the microcracks will lead to the generation of macroscopic fractures, which is explicitly mimicked by failure and removal of bonds between particles from the discrete element network. This physics-based modeling approach leads to realistic fracture patterns without using the empirical rock failure and fracture propagation criteria required in conventional continuum methods. Based on this model, a sensitivity study is performed to investigate the effects of perforation spacing, in-situ stress anisotropy, rock properties (Young's modulus, Poisson's ratio, and compressive strength), fluid properties, and natural fracture properties on hydraulic fracture propagation. In addition, since reservoirs are buried thousands of feet below the surface, the

  15. Tuning Fractures With Dynamic Data

    Science.gov (United States)

    Yao, Mengbi; Chang, Haibin; Li, Xiang; Zhang, Dongxiao

    2018-02-01

    Flow in fractured porous media is crucial for production of oil/gas reservoirs and exploitation of geothermal energy. Flow behaviors in such media are mainly dictated by the distribution of fractures. Measuring and inferring the distribution of fractures is subject to large uncertainty, which, in turn, leads to great uncertainty in the prediction of flow behaviors. Inverse modeling with dynamic data may assist to constrain fracture distributions, thus reducing the uncertainty of flow prediction. However, inverse modeling for flow in fractured reservoirs is challenging, owing to the discrete and non-Gaussian distribution of fractures, as well as strong nonlinearity in the relationship between flow responses and model parameters. In this work, building upon a series of recent advances, an inverse modeling approach is proposed to efficiently update the flow model to match the dynamic data while retaining geological realism in the distribution of fractures. In the approach, the Hough-transform method is employed to parameterize non-Gaussian fracture fields with continuous parameter fields, thus rendering desirable properties required by many inverse modeling methods. In addition, a recently developed forward simulation method, the embedded discrete fracture method (EDFM), is utilized to model the fractures. The EDFM maintains computational efficiency while preserving the ability to capture the geometrical details of fractures because the matrix is discretized as structured grid, while the fractures being handled as planes are inserted into the matrix grids. The combination of Hough representation of fractures with the EDFM makes it possible to tune the fractures (through updating their existence, location, orientation, length, and other properties) without requiring either unstructured grids or regridding during updating. Such a treatment is amenable to numerous inverse modeling approaches, such as the iterative inverse modeling method employed in this study, which is

  16. Reheat cracking of austenitic stainless steels - pre-strain effect on intergranular damage; Fissuration en relaxation des aciers inoxydables austenitiques - influence de l'ecrouissage sur l'endommagement intergranulaire

    Energy Technology Data Exchange (ETDEWEB)

    Auzoux, Q

    2004-01-01

    Welding process induces strain in 316 stainless steel affected zones. Their microstructure was reproduce by rolling of three different steels (316L, 316L(N) et 316H). Traction, creep and relaxation tests were performed at 550 deg C and 600 deg C on smooth, notched and pre-cracked specimens. Pre-strain by rolling increases the hardness and the creep resistance because of the high dislocation density but decreases ductility because of the fast development of intergranular damage. This embrittlement leads to crack propagation during relaxation tests on pre-strained steels without distinction in respect to their carbon or nitrogen content. A new intergranular damage model was built using local micro-cracks measurements and finite elements analysis. Pre-strain effect and stress triaxiality ratio effect are reproduced by the modelling so that the reheat cracking risk near welds can now be estimated. (author)

  17. Analysis of Intergranular Precipitation in Isothermally Aged Nitrogen-Containing Austenitic Stainless Steels by an Electrochemical Method and Its Relation to Cryogenic Toughness

    Directory of Open Access Journals (Sweden)

    Maribel L. Saucedo-Muñoz

    2011-01-01

    Full Text Available The precipitation process in two N-containing austenitic stainless steels, aged at temperatures between 873 and 1173 K for times from 10 to 1000 min, was analyzed by an electrochemical method based on the anodic polarization test with an electrolyte of 1 N KOH solution. The anodic polarization curves showed the following intergranular precipitation sequence: austenite → austenite + Cr23C6→ austenite + Cr23C6 + Cr2N. Besides, the fastest precipitation kinetics was detected in the aged steel with the highest content of nitrogen and carbon due to its higher driving force for precipitation. The higher the aging temperature, the higher volume fraction of precipitates. The precipitation fraction can be associated with the current density of the dissolution peaks of each phase. The Charpy-V-Notch impact energy of the aged specimens decreased with the increase in the volume fraction of precipitates.

  18. Impact of Annealing Prior to Solution Treatment on Aging Precipitates and Intergranular Corrosion Behavior of Al-Cu-Li Alloy 2050

    Science.gov (United States)

    Ye, Zhi-hao; Cai, Wen-xin; Li, Jin-feng; Chen, Xiang-rong; Zhang, Rui-feng; Birbilis, Nick; Chen, Yong-lai; Zhang, Xu-hu; Ma, Peng-cheng; Zheng, Zi-qiao

    2018-04-01

    The influences of annealing prior to solution treatment on the grain structure, subsequent aging precipitates, and intergranular corrosion (IGC) of Al-Cu-Li alloy (AA2050) sheet with T6 aging at 448 K (175 °C) were investigated. Annealing impedes the full recrystallization during solution treatment, increasing the population density of T1 (Al2CuLi) precipitates, but decreasing that of θ' (Al2Cu) precipitates, of the aged alloy. Meanwhile, annealing leads to the heterogeneous distribution of T1 precipitates, increasing the alloy hardness, and decreasing the open-circuit potential of the aged alloy. With prolonged aging time, the corrosion mode of the aged AA2050 samples with and without annealing evolved in a similar manner. The corrosion mode as a function of aging may be summarized as local IGC with pitting and general IGC with pitting (following initial aging and under the underaged condition), pitting corrosion (later in the under-aging stage), pitting with slight IGC (near the peak-aged condition), and pitting with local IGC (under the overaging condition). The annealing treatment hinders IGC propagation on the rolling surface while accelerating the IGC on transverse surfaces.

  19. Evaluation of the IGSCC(Intergranular Stress Corrosion Cracking) resistance of inconel alloys by static potential method in high temperature and high pressure environment

    International Nuclear Information System (INIS)

    Maeng, Wan Young; Nam, Tae Woon

    1997-01-01

    Inconel alloys which have good high temperature mechanical properties and corrosion resistance have been used extensively as steam generator tube of nuclear power plants. There have been some reports on the intergranular stress corrosion cracking (IGSCC) failure problems in steam generator tubes of nuclear reactors. In order to evaluate the effects of heat treatment and composition on the IGSCC behavior of inconel alloys in simulated nuclear reactor environment, four different specimens (inconel 600 MA, 600 TT, 690 MA and 690 TT) were prepared and tested by eletrochemical method. Static potential tests for stressed C-ring type inconel specimens were carried out in 10% NaOH solution at 300 deg C (75 atm). It was found that IGSCC was initiated in inconel 600 MA specimen, but the other three specimens were not cracked. Based on the gradients of corrosion current density of the four specimens as a function of test time, thermally treated alloys show better IGSCC resistance than mull-annealed alloys, and inconel 690 TT has better passivation characteristic than inconel 600 MA. Inconel 690 TT shows clear periodic passivation that indicates good SCC resistance. The good IGSCC resistance of inconel 690 TT is due to periodic passivation characteristics of surface layer. (author)

  20. Effects of ageing conditions on the precipitates evolution, chromium depletion and intergranular corrosion susceptibility of AISI 316L: experimental and modeling results

    Energy Technology Data Exchange (ETDEWEB)

    Sahlaoui, H.; Makhlouf, K.; Sidhom, H.; Philibert, J

    2004-05-15

    Chromium carbides and intermetallic phases which form in industrial AISI 316L stainless steel during ageing for up to 80 000 h between 550 and 650 deg. C were identified by combining transmission electron microscopy (TEM) thin foil imaging and electron diffraction and used to establish the time-temperature-precipitation (TTP) diagram. Following the precipitation phenomena, the chemical changes in the grain boundary region were determined by energy-dispersive X-ray microprobe analysis using a scanning transmission electron microscope (STEM). From the experimentally determined chromium profiles the chromium depleted zones were quantified. The interactions between carbide precipitation involving chromium depletion and intergranular corrosion (IGC) were clearly visible from superposition of TTP diagrams and time-temperature-sensitization (TTS) diagrams obtained from ASTM standardized tests. In addition, an experimental criterion to sensitization-desensitization phenomenon was established. Moreover, an analytical model has been developed in this study and successfully validated to predict the profiles of chromium depleted zones. This model coupled with the previously described criterion provides TTS diagrams in good agreement with experimental results.

  1. Investigation of thermally sensitised stainless steels as analogues for spent AGR fuel cladding to test a corrosion inhibitor for intergranular stress corrosion cracking

    Science.gov (United States)

    Whillock, Guy O. H.; Hands, Brian J.; Majchrowski, Tom P.; Hambley, David I.

    2018-01-01

    A small proportion of irradiated Advanced Gas-cooled Reactor (AGR) fuel cladding can be susceptible to intergranular stress corrosion cracking (IGSCC) when stored in pond water containing low chloride concentrations, but corrosion is known to be prevented by an inhibitor at the storage temperatures that have applied so far. It may be necessary in the future to increase the storage temperature by up to ∼20 °C and to demonstrate the impact of higher temperatures for safety case purposes. Accordingly, corrosion testing is needed to establish the effect of temperature increases on the efficacy of the inhibitor. This paper presents the results of studies carried out on thermally sensitised 304 and 20Cr-25Ni-Nb stainless steels, investigating their grain boundary compositions and their IGSCC behaviour over a range of test temperatures (30-60 °C) and chloride concentrations (0.3-10 mg/L). Monitoring of crack initiation and propagation is presented along with preliminary results as to the effect of the corrosion inhibitor. 304 stainless steel aged for 72 h at 600 °C provided a close match to the known pond storage corrosion behaviour of spent AGR fuel cladding.

  2. Model of T-Type Fracture in Coal Fracturing and Analysis of Influence Factors of Fracture Morphology

    Directory of Open Access Journals (Sweden)

    Yuwei Li

    2018-05-01

    Full Text Available Special T-type fractures can be formed when coal is hydraulically fractured and there is currently no relevant theoretical model to calculate and describe them. This paper first establishes the height calculation model of vertical fractures in multi-layered formations and deduces the stress intensity factor (SIF at the upper and lower sides of the fracture in the process of vertical fracture extension. Combined with the fracture tip stress analysis method of fracture mechanics theory, the horizontal bedding is taken into account for tensile and shear failure, and the critical mechanical conditions for the formation of horizontal fracture in coal are obtained. Finally, the model of T-type fracture in coal fracturing is established, and it is verified by fracturing simulation experiments. The model calculation result shows that the increase of vertical fracture height facilitates the increase of horizontal fracture length. The fracture toughness of coal has a significant influence on the length of horizontal fracture and there is a threshold. When the fracture toughness is less than the threshold, the length of horizontal fracture remains unchanged, otherwise, the length of horizontal fracture increases rapidly with the increase of fracture toughness. When the shear strength of the interface between the coalbed and the interlayer increases, the length of the horizontal fracture of the T-type fracture rapidly decreases.

  3. Pressure suppression device

    International Nuclear Information System (INIS)

    Yoshida, Toyokazu.

    1976-01-01

    Purpose: To provide a pressure suppression device for a gas cooled reactor wherein the coolant is discharged in a reactor building by a loss-of-coolant accident or the like, the increase in the pressure and temperature is controlled and thermal energy of the discharged coolant of high temperature and high pressure can be absorbed. Constitution: A low heat source unit is provided at the upper part in an inner space of a reactor building provided around the reactor, and at the upper part of the low heat source unit a stirring fan for mixing gas within the building, and a low heat source circulating the low heat source through a pipe is connected to the low heat source unit. The low heat source unit is provided with the pipe arranged in a spiral shape at the upper part of the space of the unit, and a large number of fins are provided at the outer surface of the pipe for increasing the transmission area and improve the heat exchange. When the coolant of high temperature and high pressure has been lost in the building, the thermal energy of the coolant is absorbed by the low heat source unit. (Aizawa, K.)

  4. Applicability of the fracture toughness master curve to irradiated reactor pressure vessel steels

    International Nuclear Information System (INIS)

    Sokolov, M.A.; McCabe, D.E.; Alexander, D.J.; Nanstad, R.K.

    1997-01-01

    -thick (25-mm)] specimen. Thus, fracture toughness of the material can be described by a fracture toughness-based reference temperature rather that by a temperature derived from a combination of drop-weight and Charpy impact tests. A statistical size correction based upon weakest-link theory is used to adjust the measured fracture toughness to that expected from a 1T specimen. Although the details of a consensus procedure is still under development, the basic procedure is widely used now to characterize elastic-plastic K Jc values in the transition range. For application to commercial nuclear RPVs, however, various uncertainties are being investigated as part of the Heavy-Section Steel Irradiation (HSSI) Program managed by the Oak Ridge National laboratory (ORNL) for the U.S. Nuclear Regulatory Commission. These include the use of relatively small specimens, e.g., precracked CVN (PCVN) and smaller size specimens, the applicability of the master curve to highly irradiated steels, and the effects of intergranular fracture. (author)

  5. FRACTURE SHAFT HUMERUS: INTERLOCKING

    Directory of Open Access Journals (Sweden)

    Deepak Kaladagi

    2014-12-01

    Full Text Available BACKGROUND: The incidence of humeral fracture has significantly increased during the present years due to the population growth and road traffic, domestic, industrial, automobile accidents & disasters like tsunami, earthquakes, head-on collisions, polytrauma etc. In order to achieve a stable fixation followed by early mobilization, numerous surgical implants have been devised. PURPOSE: The purpose of this study is to analyze the results of intramedullary fixation of proximal 2/3rd humeral shaft fractures using an unreamed interlocking intramedullary nail. INTRODUCTION: In 40 skeletally matured patients with fracture shaft of humerus admitted in our hospital, we used unreamed antegrade interlocking nails. MATERIAL: We carried out a prospective analysis of 40 patients randomly selected between 2001 to 2014 who were operated at JNMC Belgaum, MMC Mysore & Navodaya Medical College, Raichur. All cases were either RTAs, Domestic, Industrial, automobile accidents & also other modes of injury. METHOD: Routine investigations with pre-anaesthetic check-up & good quality X-rays of both sides of humerus was taken. Time of surgery ranged from 5-10 days from the time of admission. Only upper 1/3rd & middle 1/3rd humeral shaft fractures were included in the study. In all the cases antegrade locked unreamed humeral nails were inserted under C-arm. Patient was placed in supine position & the shoulder was kept elevated by placing a sandbag under the scapula. In all patients incision taken from tip of acromion to 3cm over deltoid longitudinally. Postoperatively sling applied with wrist & shoulder movements started after 24 hours. All the patients ranged between the age of 21-50 years. RESULTS: Total 40 patients were operated. Maximum fracture site were in the middle third- 76%, 14% upper 1/3rd. All 40 patients achieved union. The average time of union was 8-10 weeks. All patients regained full range of movements except in few cases, where there was shoulder

  6. Pelvic and acetabular fractures

    International Nuclear Information System (INIS)

    Mears, D.C.; Rubash, H.E.

    1986-01-01

    This treatise focuses primarily on the clinical aspects of diagnosis and treatments of pelvic and acetabular fractures. However, considerable attention is also paid to the radiographic diagnosis of trauma and postoperative effects. The book begins with a succinct review of pelvic and acetabular anatomy and pelvic biomechanics. It continues with a radiographic classification of pelvic injury, which will represent the major source of the book's interest for radiologists. The remainder of the book is concerned with clinical management of pelvic and acetabular trauma, including preoperative planning, surgical approaches, techniques of reduction, internal fixation, eternal fixation, post-operative care, and late problems. Even throughout this later portion of the book there are extensive illustrations, including plain radiographs, computed tomographic (CT) scans, reconstructed three-dimensional CT scans, and schematic diagrams of diverse pelvic and acetabular fractures and the elementary surgical techniques for their repair

  7. Double segmental tibial fractures - an unusual fracture pattern

    Directory of Open Access Journals (Sweden)

    Bali Kamal

    2012-02-01

    Full Text Available 【Abstract】A case of a 50-year-old pedestrian who was hit by a bike and suffered fractures of both bones of his right leg was presented. Complete clinical and radiographic assessment showed double segmental fractures of the tibia and multisegmental fractures of the fibula. Review of the literature revealed that this fracture pattern was unique and only a single case was reported so far. Moreover, we discussed the possible mechanisms which can lead to such an injury. We also discussed the management of segmental tibial fracture and the difficulties encountered with them. This case was managed by modern osteosynthesis tech- nique with a pleasing outcome. Key words: Fracture, bone; Tibia; Fibula; Nails

  8. FRACTURED PETROLEUM RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Abbas Firoozabadi

    1999-06-11

    The four chapters that are described in this report cover a variety of subjects that not only give insight into the understanding of multiphase flow in fractured porous media, but they provide also major contribution towards the understanding of flow processes with in-situ phase formation. In the following, a summary of all the chapters will be provided. Chapter I addresses issues related to water injection in water-wet fractured porous media. There are two parts in this chapter. Part I covers extensive set of measurements for water injection in water-wet fractured porous media. Both single matrix block and multiple matrix blocks tests are covered. There are two major findings from these experiments: (1) co-current imbibition can be more efficient than counter-current imbibition due to lower residual oil saturation and higher oil mobility, and (2) tight fractured porous media can be more efficient than a permeable porous media when subjected to water injection. These findings are directly related to the type of tests one can perform in the laboratory and to decide on the fate of water injection in fractured reservoirs. Part II of Chapter I presents modeling of water injection in water-wet fractured media by modifying the Buckley-Leverett Theory. A major element of the new model is the multiplication of the transfer flux by the fractured saturation with a power of 1/2. This simple model can account for both co-current and counter-current imbibition and computationally it is very efficient. It can be orders of magnitude faster than a conventional dual-porosity model. Part II also presents the results of water injection tests in very tight rocks of some 0.01 md permeability. Oil recovery from water imbibition tests from such at tight rock can be as high as 25 percent. Chapter II discusses solution gas-drive for cold production from heavy-oil reservoirs. The impetus for this work is the study of new gas phase formation from in-situ process which can be significantly

  9. Characterization by notched and precracked Charpy tests of the in-service degradation of RPV steel fracture toughness

    Energy Technology Data Exchange (ETDEWEB)

    Fabry, A.

    1997-01-01

    provides substantial information used for the modelling of in-service steel strenthening, intergranular fracture susceptibility and other irradiation-induced and ageing effects.

  10. Characterization by notched and precracked Charpy tests of the in-service degradation of RPV steel fracture toughness

    International Nuclear Information System (INIS)

    Fabry, A.

    1997-01-01

    information used for the modelling of in-service steel strenthening, intergranular fracture susceptibility and other irradiation-induced and ageing effects

  11. Innovations in the management of hip fractures.

    Science.gov (United States)

    Teasdall, Robert D; Webb, Lawrence X

    2003-08-01

    Hip fractures include fractures of the head, neck, intertrochanteric, and subtrochanteric regions. Head fractures commonly accompany dislocations. Neck fractures and intertrochanteric fractures occur with greatest frequency in elderly patients with a low bone mineral density and are produced by low-energy mechanisms. Subtrochanteric fractures occur in a predominantly strong cortical osseous region that is exposed to large compressive stresses. Implants used to address these fractures must accommodate significant loads while the fractures consolidate. Complications secondary to hip fractures produce significant morbidity and include infection, nonunion, malunion, decubitus ulcers, fat emboli, deep venous thrombosis, pulmonary embolus, pneumonia, myocardial infarction, stroke, and death.

  12. Effects of Dy{sub 71.5}Fe{sub 28.5} intergranular addition on the microstructure and the corrosion resistance of Nd–Fe–B sintered magnets

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Liping; Ma, Tianyu, E-mail: maty@zju.edu.cn; Zhang, Pei; Yan, Mi, E-mail: mse_yanmi@zju.edu.cn

    2015-06-15

    To satisfy high-temperature applications, heavy rare-earth (RE) Dy is commonly introduced into the Nd–Fe–B sintered magnets to improve the coercivity. In addition to forming (Nd, Dy){sub 2}Fe{sub 14}B, Dy also exists in the intergranular RE-rich phase. Hence, understanding the effect of Dy on the electrochemical characteristics of the RE-rich phase and corrosion resistance of the magnet is of importance. In this work, eutectic alloy Dy{sub 71.5}Fe{sub 28.5} powders were added into the (Pr{sub 0.2}Nd{sub 0.8}){sub 12.3}Fe{sub bal}B{sub 6.1} magnet through binary-alloy approach to investigate the corrosion resistance of the magnet in electrochemical and hot/humid environments. The results demonstrate that Dy is enriched in the intergranular phase, improving its electrode potential and stability due to the higher electrode potential of Dy than Nd or Pr. As a consequence, the electrode potential difference between the 2:14:1 phase and the RE-rich phase is reduced, improving the corrosion resistance. Furthermore, formation of (Pr, Nd, Dy){sub 2}Fe{sub 14}B shell with stronger local anisotropy surrounding the 2:14:1 phase grains improves the coercivity with a slight remanence loss. Therefore, intergranular adding Dy–Fe alloy powders can obtain both high magnetic properties and good corrosion resistance simultaneously. - Highlights: • Eutectic Dy{sub 71.5}Fe{sub 28.5} powders were intergranular added to NdFeB sintered magnets. • The doped magnet showed improved corrosion resistance compared to Dy-free magnet. • Dy enrichment in RE-rich intergranular phase improved its electrode potential. • (Nd, Dy){sub 2}Fe{sub 14}B shell was expected to form in the surface of Nd{sub 2}Fe{sub 14}B grains. • Both corrosion resistance and coercivity were improved in Dy–Fe doped magnet.

  13. Characterisation of fracture network and groundwater preferential ...

    African Journals Online (AJOL)

    Characterisation of fractured rocks and evaluation of fracture connectivity are essential for the study of subsurface flow and transport in fractured rock aquifers. In this study, we use a new method to present fracture networks and analyse the connectivity of the fractures, based on the technique of randomly-generated ...

  14. On size effects in fracture

    International Nuclear Information System (INIS)

    Sinclair, G.B.

    1985-01-01

    This paper discusses the dependence of fracture stress on size. This conclusion is based on classical energy arguments. For an in-plane scaled specimen pair, the larger the specimen the smaller the fracture stress. In contrast the same theory gives a different dependence for out-of-plane specimen and the dependence involves plane stress, strain, fracture stresses and Poisson's ratio. The objective of this paper is to examine how well these predictions are actually complied with

  15. Overview of Mandibular Condyle Fracture

    OpenAIRE

    Park, Su-Seong; Lee, Keun-Cheol; Kim, Seok-Kwun

    2012-01-01

    The mandibular condyle is a region that plays a key role in the opening and closing of the mouth, and because fracture causes functional and aesthetic problems such as facial asymmetry, it is very important to perform accurate reduction. Traditionally, there has been disagreement on how to manage fracture of the mandibular condyle. This review explores the misunderstanding of mandibular condyle fracture treatment and modern-day treatment strategies.

  16. Overview of Mandibular Condyle Fracture

    Directory of Open Access Journals (Sweden)

    Su-Seong Park

    2012-07-01

    Full Text Available The mandibular condyle is a region that plays a key role in the opening and closing of the mouth, and because fracture causes functional and aesthetic problems such as facial asymmetry, it is very important to perform accurate reduction. Traditionally, there has been disagreement on how to manage fracture of the mandibular condyle. This review explores the misunderstanding of mandibular condyle fracture treatment and modern-day treatment strategies.

  17. Overview of Mandibular Condyle Fracture

    Directory of Open Access Journals (Sweden)

    Su-Seong Park

    2012-07-01

    Full Text Available The mandibular condyle is a region that plays a key role in the opening and closing ofthe mouth, and because fracture causes functional and aesthetic problems such as facialasymmetry, it is very important to perform accurate reduction. Traditionally, there has beendisagreement on how to manage fracture of the mandibular condyle. This review exploresthe misunderstanding of mandibular condyle fracture treatment and modern-day treatmentstrategies.

  18. Golfer's fracture of the ribs

    International Nuclear Information System (INIS)

    Lim, J. H.

    1980-01-01

    Golfer's fracture is stress fracture of the posterior portion of left 3, 4, 5, 6 or 7th ribs of golfer's, usually beginners,and it is considered due to exposure to unaccustomed severe exercise of this fascinating sport. Healing is usually uneventful, but possible complication may occur, because symptom is mild and golfers continue the exercise with physical therapy such as massage. Author report 4 cases of golfer's fracture, including 1 case complicated by platelike at electasis of lung.

  19. Golfer's fracture of the ribs

    Energy Technology Data Exchange (ETDEWEB)

    Lim, J H [Seoul District Armed Forces General Hospital, Seoul (Korea, Republic of)

    1980-06-15

    Golfer's fracture is stress fracture of the posterior portion of left 3, 4, 5, 6 or 7th ribs of golfer's, usually beginners,and it is considered due to exposure to unaccustomed severe exercise of this fascinating sport. Healing is usually uneventful, but possible complication may occur, because symptom is mild and golfers continue the exercise with physical therapy such as massage. Author report 4 cases of golfer's fracture, including 1 case complicated by platelike at electasis of lung.

  20. Torsion fracture of carbon nanocoils

    Science.gov (United States)

    Yonemura, Taiichiro; Suda, Yoshiyuki; Tanoue, Hideto; Takikawa, Hirofumi; Ue, Hitoshi; Shimizu, Kazuki; Umeda, Yoshito

    2012-10-01

    We fix a carbon nanocoil (CNC) on a substrate in a focused ion beam instrument and then fracture the CNC with a tensile load. Using the CNC spring index, we estimate the maximum to average stress ratio on the fractured surface to range from 1.3 to 1.7, indicating stress concentration on the coil wire inner edge. Scanning electron microscopy confirms a hollow region on the inner edge of all fractured surfaces.

  1. Experimental study upon the effect of irradiation on callus formation of fracture. Observation of vascular alteration and callus formation

    Energy Technology Data Exchange (ETDEWEB)

    Saigusa, F [Nippon Dental Coll., Tokyo

    1981-02-01

    Irradiation effects on callus formation after bone fracture were studied in rats with fractured right lower extremity. Follow-up study was continued for 112 days since 3000 rad was irradiated to the fractured site 3 days after bone fracture. Callus formation was noted in both of the outer and inner part (bone marrow) of the diaphysis before 14 days after bone fracture, but it was slow and sparse compared with that of non-irradiated group. Callus formation tended to disappear gradually from the outside of the diaphysis after 28 days after bone fracture. Strong disturbance was found in the surrounding vascular system at this time. Inside of the diaphysis, callus formation was restricted the end of the fracture, where lamellar calluses fused together. Changes in vascular system remained until 56 days after bone fracture. Vascular distribution was most dense 28 days after bone fracture. In many of the calluses which have established fusion, findings suggested excessive calcification in the trabeculae. Vascular distribution at this time was sparse, vascular formation was markedly suppressed in the bone marrow, and very little vascular formation was found in the fractured edges of the bone.

  2. A NEW HIGH RESOLUTION OPTICAL METHOD FOR OBTAINING THE TOPOGRAPHY OF FRACTURE SURFACES IN ROCKS

    Directory of Open Access Journals (Sweden)

    Steven Ogilvie

    2011-05-01

    Full Text Available Surface roughness plays a major role in the movement of fluids through fracture systems. Fracture surface profiling is necessary to tune the properties of numerical fractures required in fluid flow modelling to those of real rock fractures. This is achieved using a variety of (i mechanical and (ii optical techniques. Stylus profilometry is a popularly used mechanical method and can measure surface heights with high precision, but only gives a good horizontal resolution in one direction on the fracture plane. This method is also expensive and simultaneous coverage of the surface is not possible. Here, we describe the development of an optical method which images cast copies of rough rock fractures using in-house developed hardware and image analysis software (OptiProf™ that incorporates image improvement and noise suppression features. This technique images at high resolutions, 15-200 μm for imaged areas of 10 × 7.5 mm and 100 × 133 mm, respectively and a similar vertical resolution (15 μm for a maximum topography of 4 mm. It uses in-house developed hardware and image analysis (OptiProf™ software and is cheap and non-destructive, providing continuous coverage of the fracture surface. The fracture models are covered with dye and fluid thicknesses above the rough surfaces converted into topographies using the Lambert-Beer Law. The dye is calibrated using 2 devices with accurately known thickness; (i a polycarbonate tile with wells of different depths and (ii a wedge-shaped vial made from silica glass. The data from each of the two surfaces can be combined to provide an aperture map of the fracture for the scenario where the surfaces touch at a single point or any greater mean aperture. The topography and aperture maps are used to provide data for the generation of synthetic fractures, tuned to the original fracture and used in numerical flow modelling.

  3. Clavicular fractures: Classification, diagnosis, therapy

    International Nuclear Information System (INIS)

    Schunk, K.; Strunk, H.; Schild, H.; Lohr, S.

    1988-01-01

    Clavicular fracture is one of the most frequent skeletal lesions. In most cases the median third of the clavicula is affected (this is due to the peculiar biomechanical structure). Accompanying lesions and complications of clavicular fractures are rare. A total of 13 X-ray diagnostic techniques are described of clavicular fractures. X-ray film should, as a matter of principle, always be taken in two planes. Definitely the major part of clavicular fractures are treated conservatively (rucsac dressing), whereas surgery is reserved for few and strictly defined indications. (orig.) [de

  4. [Intramedullary stabilisation of clavicula fractures].

    Science.gov (United States)

    Prokop, A; Schiffer, G; Jubel, A; Chmielnicki, M

    2013-10-01

    With an incidence of 64/100,000, clavicular shaft fractures are one of the most common fractures. Intramedullary fixation with Prevot nails was initially reported in the late 1990s. This procedure offers minimally invasive stabilization of the fracture, thus enabling immediate mobilization and rapid loading capacity. Using a case study, the positioning and procedure are demonstrated on video. The intramedullary implant accommodates the varying tension loading of the clavicle. This treatment is ideal for clavicular fractures with 2-3 fragments. Compared to patients treated conservatively, operated patients achieve more rapid and improved mobility. Employment disability is shorter, and malunion occurs less frequently. Georg Thieme Verlag KG Stuttgart · New York.

  5. Clavicular fractures: Classification, diagnosis, therapy

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, K.; Strunk, H.; Schild, H.; Lohr, S.

    1988-09-01

    Clavicular fracture is one of the most frequent skeletal lesions. In most cases the median third of the clavicula is affected (this is due to the peculiar biomechanical structure). Accompanying lesions and complications of clavicular fractures are rare. A total of 13 X-ray diagnostic techniques are described of clavicular fractures. X-ray film should, as a matter of principle, always be taken in two planes. Definitely the major part of clavicular fractures are treated conservatively (rucsac dressing), whereas surgery is reserved for few and strictly defined indications.

  6. Management of civilian ballistic fractures.

    Science.gov (United States)

    Seng, V S; Masquelet, A C

    2013-12-01

    The management of ballistic fractures, which are open fractures, has often been studied in wartime and has benefited from the principles of military surgery with debridement and lavage, and the use of external fixation for bone stabilization. In civilian practice, bone stabilization of these fractures is different and is not performed by external fixation. Fifteen civilian ballistic fractures, Gustilo II or IIIa, two associated with nerve damage and none with vascular damage, were reviewed. After debridement and lavage, ten internal fixations and five conservative treatments were used. No superficial or deep surgical site infection was noted. Fourteen of the 15 fractures (93%) healed without reoperation. Eleven of the 15 patients (73%) regained normal function. Ballistic fractures have a bad reputation due to their many complications, including infections. In civilian practice, the use of internal fixation is not responsible for excessive morbidity, provided debridement and lavage are performed. Civilian ballistic fractures, when they are caused by low-velocity firearms, differ from military ballistic fractures. Although the principle of surgical debridement and lavage remains the same, bone stabilization is different and is similar to conventional open fractures. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  7. Rehabilitation after falls and fractures.

    Science.gov (United States)

    Dionyssiotis, Y; Dontas, I A; Economopoulos, D; Lyritis, G P

    2008-01-01

    Falls are one of the most common geriatric problems threatening the independence of older persons. Elderly patients tend to fall more often and have a greater tendency to fracture their bones. Fractures occur particularly in osteoporotic people due to increased bone fragility, resulting in considerable reduction of quality of life, morbidity, and mortality. This article provides information for the rehabilitation of osteoporotic fractures pertaining to the rehabilitation of the fractured patient, based on personal experience and literature. It also outlines a suggested effective and efficient clinical strategy approach for preventing falls in individual patients.

  8. A newborn with multiple fractures

    International Nuclear Information System (INIS)

    Kantorova, E.; Kratky, L.; Nevsimal, I.; Marik, K.; Kozlowski, K.

    2008-01-01

    Sometimes newborns with multiple fractures are diagnosed as osteogenesis imperfecta in spite of absence of radiographic findings supporting this diagnosis. A newborn with multiple fractures was diagnosed as osteogenesis imperfecta. Analysis of the structure of the long bones, pattern of fractures and poorly developed muscles suggested the diagnosis of fetal akinesia deformation syndrome. This was confirmed by pregnancy history and clinical findings. Multiple fractures in a newborn may present with diagnostic radiographic features as in osteogenesis imperfecta, or as in lethal gracile bone dysplasias or achondrogenesis type IA. If those features are absent, other diseases should be considered. Radiographs should be compared with pregnancy history and clinical findings in the newborn. (authors)

  9. Hydraulic properties of fracture networks

    International Nuclear Information System (INIS)

    Dreuzy, J.R. de

    1999-12-01

    Fractured medium are studied in the general framework of oil and water supply and more recently for the underground storage of high level nuclear wastes. As fractures are generally far more permeable than the embedding medium, flow is highly channeled in a complex network of fractures. The complexity of the network comes from the broad distributions of fracture length and permeability at the fracture scale and appears through the increase of the equivalent permeability at the network scale. The goal of this thesis is to develop models of fracture networks consistent with both local-scale and global-scale observations. Bidimensional models of fracture networks display a wide variety of flow structures ranging from the sole permeable fracture to the equivalent homogeneous medium. The type of the relevant structure depends not only on the density and the length and aperture distributions but also on the observation scale. In several models, a crossover scale separates complex structures highly channeled from more distributed and homogeneous-like flow patterns at larger scales. These models, built on local characteristics and validated by global properties, have been settled in steady state. They have also been compared to natural well test data obtained in Ploemeur (Morbihan) in transient state. The good agreement between models and data reinforces the relevance of the models. Once validated and calibrated, the models are used to estimate the global tendencies of the main flow properties and the risk associated with the relative lack of data on natural fractures media. (author)

  10. Fracture Mechanisms in Steel Castings

    Directory of Open Access Journals (Sweden)

    Stradomski Z.

    2013-09-01

    Full Text Available The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism of decohesion - the intergranular one - occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C revealed low or very low strength of high-carbon cast steels.

  11. Fracture network growth for prediction of fracture characteristics and connectivity in tight reservoir rocks

    NARCIS (Netherlands)

    Barnhoorn, A.; Cox, S.F.

    2012-01-01

    Fracturing experiments on very low-porosity dolomite rocks shows a difference in growth of fracture networks by stress-driven fracturing and fluid-driven fracturing. Stress-driven fracture growth, in the absence of fluid pressure, initially forms fractures randomly throughout the rocks followed by

  12. Differential equilibration and intergranular diffusion of trace elements during rapid regional metamorphism: constraints from LA-ICP-MS mapping of a garnet population

    Science.gov (United States)

    George, F. R.; Gaidies, F.

    2017-12-01

    Trace element zoning contained within a metapelitic garnet population yields information pertaining to a more complex prograde reaction history than is evident in major element zoning patterns and other conventional analyses. In particular, while trace elements may not act as a rate-limiting component for garnet crystallization, their incorporation into garnet growth surfaces provides a nuanced insight into the crystallization history of the population, and the extent of equilibration of trace elements in the matrix. In this study, we present LA-ICP-MS raster maps of trace element concentrations from several population-representative, centrally sectioned garnets from a garnet-grade metapelite of the Sikkim Himalaya, India. Equilibrium forward modeling of garnet crystallization and simulation of diffusional modification indicates that the garnet population crystallized rapidly over <1 Myr between 515 °C/4.5 kbar and 565 °C/5.5 kbar, as a consequence of high heating rates during regional amphibolite-facies metamorphism. While the rate of diffusional homogenization of major divalent cations is interpreted to have exceeded the rate of interfacial advance (yielding simple prograde growth zoning), trace element distributions record a more complex transport history. In particular, yttrium and the heavy rare earth elements (HREE) document a transition from an overprinted sigmoidal core to concentric repeated HREE and yttrium annuli in all crystals. This suggests that there was a discrete increase in the length scale of equilibration along the advancing garnet interface at some point in the growth history. However, there is no evidence for a coeval change in HREE transport thorough the intergranular network. Conversely, spiral core-to-rim zoning of chromium indicates the element remains almost completely immobile in the matrix over the duration of garnet growth.

  13. Differences between groundwater fauna in shallow and in deep intergranular aquifers as an indication of different characteristics of habitats and hydraulic connections

    Directory of Open Access Journals (Sweden)

    Anton Brancelj

    2016-03-01

    Full Text Available The fauna in the hyporheic zones of rivers has been relatively well studied but that from the phreatic zone remains comparatively unknown and there are few investigations into deeper intergranular aquifers (over 30 m in depth due to technical difficulties. Two shallow boreholes of 29 m depth and two deep boreholes of 100 m depth, both near Ljubljana (Slovenia, were sampled more than 30 times between 14 January 2008 and 3 March 2009.  On each occasion 14.4 to 18.0 m3 of water were abstracted using a high-capacity pump, then filtered by means of a plankton net with a mesh size of 60 µm. Organisms larger than 2 mm were damaged by the pump rotors, but their identification was still possible, while smaller representatives of the Copepoda (Crustacea passed the rotors without  damage. A near-by artesian borehole was sampled on 6 occasions. Water chemistry, physical properties and faunal composition analyses were carried out for each borehole. A total of 32 taxa, 24 of which were stygobites, were identified. Copepoda alone were represented by 16 species, 15 of which were stygobites. The shallow boreholes differ from the deep boreholes in their higher temperatures and higher concentrations of K+, Na+, Ca2+, Mg2+ and SO42- ions. The copepod communities in samples from the shallow boreholes differ sharply from those from the deep boreholes. There were also clear differences between shallow boreholes in two aquifers located a few kilometres apart, in physical and chemical characteristics as well as in fauna composition. Taxa with different ecological affinities, collected from groundwater, are indicators of hydraulic connections between different parts of an aquifer as well as of communication between surface and subsurface water bodies. The present study suggests that subterranean fauna, as well as epigean fauna, can provide effective support for classical dye/salt tracing experiments.

  14. Instability in dynamic fracture

    Science.gov (United States)

    Fineberg, J.; Marder, M.

    1999-05-01

    The fracture of brittle amorphous materials is an especially challenging problem, because the way a large object shatters is intimately tied to details of cohesion at microscopic scales. This subject has been plagued by conceptual puzzles, and to make matters worse, experiments seemed to contradict the most firmly established theories. In this review, we will show that the theory and experiments fit within a coherent picture where dynamic instabilities of a crack tip play a crucial role. To accomplish this task, we first summarize the central results of linear elastic dynamic fracture mechanics, an elegant and powerful description of crack motion from the continuum perspective. We point out that this theory is unable to make predictions without additional input, information that must come either from experiment, or from other types of theories. We then proceed to discuss some of the most important experimental observations, and the methods that were used to obtain the them. Once the flux of energy to a crack tip passes a critical value, the crack becomes unstable, and it propagates in increasingly complicated ways. As a result, the crack cannot travel as quickly as theory had supposed, fracture surfaces become rough, it begins to branch and radiate sound, and the energy cost for crack motion increases considerably. All these phenomena are perfectly consistent with the continuum theory, but are not described by it. Therefore, we close the review with an account of theoretical and numerical work that attempts to explain the instabilities. Currently, the experimental understanding of crack tip instabilities in brittle amorphous materials is fairly detailed. We also have a detailed theoretical understanding of crack tip instabilities in crystals, reproducing qualitatively many features of the experiments, while numerical work is beginning to make the missing connections between experiment and theory.

  15. Compton suppression gamma ray spectrometry

    International Nuclear Information System (INIS)

    Landsberger, S.; Iskander, F.Y.; Niset, M.; Heydorn, K.

    2002-01-01

    In the past decade there have been many studies to use Compton suppression methods in routine neutron activation analysis as well as in the traditional role of low level gamma ray counting of environmental samples. On a separate path there have been many new PC based software packages that have been developed to enhance photopeak fitting. Although the newer PC based algorithms have had significant improvements, they still suffer from being effectively used in weak gamma ray lines in natural samples or in neutron activated samples that have very high Compton backgrounds. We have completed a series of experiments to show the usefulness of Compton suppression. As well we have shown the pitfalls when using Compton suppression methods for high counting deadtimes as in the case of neutron activated samples. We have also investigated if counting statistics are the same both suppressed and normal modes. Results are presented in four separate experiments. (author)

  16. Fatigue and fracture: Overview

    Science.gov (United States)

    Halford, G. R.

    1984-01-01

    A brief overview of the status of the fatigue and fracture programs is given. The programs involve the development of appropriate analytic material behavior models for cyclic stress-strain-temperature-time/cyclic crack initiation, and cyclic crack propagation. The underlying thrust of these programs is the development and verification of workable engineering methods for the calculation, in advance of service, of the local cyclic stress-strain response at the critical life governing location in hot section compounds, and the resultant crack initiation and crack growth lifetimes.

  17. Femoral shaft fractures

    International Nuclear Information System (INIS)

    Bender, C.E.; Campbell, D.C. II

    1985-01-01

    The femur is the longest, largest, and strongest bone in the body. Because of its length, width, and role as primary weight-bearing bone, it must tolerate the extremes of axial loading and angulatory stresses. Massive musculature envelopes the femur. This masculature provides abundant blood supply to the bone, which also allows great potential for healing. Thus, the most significant problem relating to femoral shaft fractures is not healing, but restoration of bone length and alignment so that the femoral shaft will tolerate the functional stresses demanded of it

  18. Fracturing of subterranean formations

    Energy Technology Data Exchange (ETDEWEB)

    Kiel, O.M.; Kidwell, A.L.

    1968-03-19

    This method of propping fractured formations results in high conductivities. In the method, certain naturally occurring crystals are used as propping agents. Suitable crystals include garnet, corundum, zircon, rutile, high-temperature quartz, and other minerals which have Moh's hardness values of about 6 or greater and weather out as individual crystals of about 40 mesh or larger. These are said to result in permeabilities significantly higher than those obtained with ordinary quartz sand, metallic shot, glass beads, plastic particles, walnut hulls, or similar materials. (10 claims)

  19. Characterisation of hydraulically-active fractures in a fractured ...

    African Journals Online (AJOL)

    ... in the initial stage of a site investigation to select the optimal site location or to evaluate the hydrogeological properties of fractures in underground exploration studies, such as those related geothermal reservoir evaluation and radioactive waste disposal. Keywords: self-potential method, hydraulically-conductive fractures, ...

  20. Quantifying Discrete Fracture Network Connectivity in Hydraulic Fracturing Stimulation

    Science.gov (United States)

    Urbancic, T.; Ardakani, E. P.; Baig, A.

    2017-12-01

    Hydraulic fracture stimulations generally result in microseismicity that is associated with the activation or extension of pre-existing microfractures and discontinuities. Microseismic events acquired under 3D downhole sensor coverage provide accurate event locations outlining hydraulic fracture growth. Combined with source characteristics, these events provide a high quality input for seismic moment tensor inversion and eventually constructing the representative discrete fracture network (DFN). In this study, we investigate the strain and stress state, identified fracture orientation, and DFN connectivity and performance for example stages in a multistage perf and plug completion in a North American shale play. We use topology, the familiar concept in many areas of structural geology, to further describe the relationships between the activated fractures and their effectiveness in enhancing permeability. We explore how local perturbations of stress state lead to the activation of different fractures sets and how that effects the DFN interaction and complexity. In particular, we observe that a more heterogeneous stress state shows a higher percentage of sub-horizontal fractures or bedding plane slips. Based on topology, the fractures are evenly distributed from the injection point, with decreasing numbers of connections by distance. The dimensionless measure of connection per branch and connection per line are used for quantifying the DFN connectivity. In order to connect the concept of connectivity back to productive volume and stimulation efficiency, the connectivity is compared with the character of deformation in the reservoir as deduced from the collective behavior of microseismicity using robustly determined source parameters.

  1. Ankle fractures have features of an osteoporotic fracture.

    Science.gov (United States)

    Lee, K M; Chung, C Y; Kwon, S S; Won, S H; Lee, S Y; Chung, M K; Park, M S

    2013-11-01

    We report the bone attenuation of ankle joint measured on computed tomography (CT) and the cause of injury in patients with ankle fractures. The results showed age- and gender-dependent low bone attenuation and low-energy trauma in elderly females, which suggest the osteoporotic features of ankle fractures. This study was performed to investigate the osteoporotic features of ankle fracture in terms of bone attenuation and cause of injury. One hundred ninety-four patients (mean age 51.0 years, standard deviation 15.8 years; 98 males and 96 females) with ankle fracture were included. All patients underwent CT examination, and causes of injury (high/low-energy trauma) were recorded. Mean bone attenuations of the talus, medial malleolus, lateral malleolus, and distal tibial metaphysis were measured on CT images. Patients were divided into younger age (fractures than the younger age group. With increasing age, bone attenuations tended to decrease and the difference of bone attenuation between the genders tended to increase in the talus, medial malleolus, lateral malleolus, and distal tibial metaphysis. Ankle fracture had features of osteoporotic fracture that is characterized by age- and gender-dependent low bone attenuation. Ankle fracture should not be excluded from the clinical and research interest as well as from the benefit of osteoporosis management.

  2. Basic principles of fracture treatment in children.

    Science.gov (United States)

    Ömeroğlu, Hakan

    2018-04-01

    This review aims to summarize the basic treatment principles of fractures according to their types and general management principles of special conditions including physeal fractures, multiple fractures, open fractures, and pathologic fractures in children. Definition of the fracture is needed for better understanding the injury mechanism, planning a proper treatment strategy, and estimating the prognosis. As the healing process is less complicated, remodeling capacity is higher and non-union is rare, the fractures in children are commonly treated by non-surgical methods. Surgical treatment is preferred in children with multiple injuries, in open fractures, in some pathologic fractures, in fractures with coexisting vascular injuries, in fractures which have a history of failed initial conservative treatment and in fractures in which the conservative treatment has no/little value such as femur neck fractures, some physeal fractures, displaced extension and flexion type humerus supracondylar fractures, displaced humerus lateral condyle fractures, femur, tibia and forearm shaft fractures in older children and adolescents and unstable pelvis and acetabulum fractures. Most of the fractures in children can successfully be treated by non-surgical methods.

  3. Thyroid suppression test with dextrothyroxine

    International Nuclear Information System (INIS)

    Rosenthal, D.; Fridman, J.; Ribeiro, H.B.

    1978-01-01

    The classic thyroid suppression test with triiodothyronine (l-T 3 ) has been shown to be efficient as an auxiliary method in the diagnosis of thyroid diseases, but should not be performed on elderly patients or on those with heart disease or a tendency to tachycardia. Since these subjects seem able to support a short period of dextro-thyronine (d-T 4 ) feeding, we compared the effect of d-T 4 and l-T 3 on the 24 hours thyroid uptake in euthyroid and hyperthyroid subjects. After basal radio-iodine uptake determination, 99 patients without hyperthyroidism and 27 with Graves' disease were randomly divided in 2 groups; one received 100μg of l-T 3 per day and the other 4 mg of d-T 4 per day, both groups being treated for a period of 10 days. At the end of this suppression period the 24 hours radio-iodine uptake was measured again and the percentual suppression index (S.I.) calculated. Since the comparison of the two groups showed no difference between the suppressive effect of l-T 3 and d-T 4 in euthyroid subjects, while dextro-thyronine, as levo-triiodothyronine, did not suppress the 24 hours uptake of hyperthyroid patients, l-T 3 or d-T 4 can be used interchangeably to test thyroid suppressibility. In the euthyroid subjects the normal range for the post-suppression uptake was 0-17.1% and for the suppression index 54,7.100% [pt

  4. Hydrologic behavior of fracture networks

    International Nuclear Information System (INIS)

    Long, J.C.S.; Endo, H.K.; Karasaki, K.; Pyrak, L.; MacLean, P.; Witherspoon, P.A.

    1984-10-01

    This paper reviews recent research on the nature of flow and transport in discontinuous fracture networks. The hydrologic behavior of these networks has been examined using two- and three-dimensional numerical models. The numerical models represent random realizations of fracture networks based on statistical field measurements of fracture geometry and equivalent hydraulic aperture. We have compared the flux and mechanical transport behavior of these networks to the behavior of equivalent continua. In this way we are able to determine whether a given fracture network can be modeled as an equivalent porous media in both flux and advective transport studies. We have examined departures from porous media behavior both as a function of interconnectivity and heterogeneity. Parameter studies have revealed behavior patterns such as: given a fracture frequency that can be measured in the field, porous media like behavior and the magnitude of permeability are both enhanced if the fractures are longer and the standard deviation of fracture permeabilities is smaller. Transport studies have shown that the ratio between flux and velocity is not necessarily constant when the direction of flow is changed in systems which do behave like a porous media for flux. Thus the conditions under which porous media analysis can be used in transport studies are more restrictive than the condition for flux studies. We have examined systems which do not behave like porous media and have shown how the in situ behavior varies as a function of scale of observation. The behavior of well tests in fractured networks has been modeled and compared to a new analytical well test solution which accounts for the early time dominance of the fractures intersecting the well. Finally, a three-dimensional fracture flow model has been constructed which assumes fractures are randomly located discs. 13 references, 12 figures

  5. Mandibular ramus fractures: a rarity.

    Science.gov (United States)

    Kale, Tejraj Pundalik; Kotrashetti, S M; Louis, Archana; Lingaraj, J B; Sarvesh, B U

    2013-01-01

    To determine the incidence of mandibular ramus fractures in KLE's PK Hospital and to analyze the outcome of open reduction and internal fixation of these fractures. Using a retrospective study design, records of all trauma patients who reported to the Department of Oral and Maxillofacial Surgery, KLE's PK Hospital Belgaum, between the years January 2006 to October 2011 was obtained from the medical records office. The data variables that were analyzed were the name, age, sex, cause of injury, pretreatment occlusion, treatment given, period of MMF and post-treatment occlusion. Total number of mandibular fracture cases was 298. Ramus fractures were 10 in number which accounted for 3.3% of fractures. The age range of these 10 patients was seen to be between 20 to 80 years with the average age being 35.6 years. Of these 10 patients, 9 were male and 1 was female and 7 patients were treated by open reduction and internal fixation and the remaining 3 by closed reduction. The average period of MMF was 3 days for the patients who underwent open reduction and internal fixation. There was improvement in occlusion in all 10 patients post-treatment and there was no complication reported in any of the cases. Ramus fractures accounted for 3.3% of all mandibular fractures. Open reduction and internal fixation of ramus fractures ensures adequate functional and anatomic reduction. This study makes an attempt to throw a light on the increasing incidence of ramus fractures and a successful management of these fractures by open reduction and internal fixation. How to cite this article: Kale TP, Kotrashetti SM, Louis A, Lingaraj JB, Sarvesh BU. Mandibular Ramus Fractures: A Rarity. J Contemp Dent Pract 2013;14(1):39-42. Source of support: Nil Conflict of interest: None declared.

  6. GUNSHOT FRACTURES OF TIBIA AND FEMUR - EXCELLENT ...

    African Journals Online (AJOL)

    2011-10-10

    Oct 10, 2011 ... fractures due to gunshot injury grafted with reamed bone marrow and immobilised with Surgical ... open fractures, which pose a challenging problem .... Table 2. Gustillo-Anderson Classification of fractures and infection.

  7. Image diagnosis of nasal bone fracture

    International Nuclear Information System (INIS)

    Hirota, Yoshiharu; Shimizu, Yayoi; Iinuma, Toshitaka.

    1988-01-01

    Twenty cases of nasal bone fractures were evaluated as to the types of fractures based upon HRCT findings. Conventional X-Ray films for nasal bones were analyzed and compared with HRCT findings. Nasal bone fractures were classified into lateral and frontal fractures. HRCT images were evaluated in three planes including upper, middle and lower portions of the nasal bone. Fractures favored males of teens. Lateral fracture gave rise to the fractures of the nasal bone opposite to the external force, loosening of the ipsilateral nasomaxillary sutures and fractures of the frontal process of the maxilla. Conventional X-Ray films were reevaluated after HRCT evaluation and indications of nasal bone fractures were determined. In addition to the discontinuity of the nasal dorsum, fracture lines parallel to and beneath the nasal dorsum and indistinct fracture lines along the nasomaxillary sutures are the indication of nasal bone fractures by conventional X-Ray films. (author)

  8. Associations of early premenopausal fractures with subsequent fractures vary by sites and mechanisms of fractures.

    Science.gov (United States)

    Honkanen, R; Tuppurainen, M; Kroger, H; Alhava, E; Puntila, E

    1997-04-01

    In a retrospective population-based study we assessed whether and how self-reported former fractures sustained at the ages of 20-34 are associated with subsequent fractures sustained at the ages of 35-57. The 12,162 women who responded to fracture questions of the baseline postal enquiry (in 1989) of the Kuopio Osteoporosis Study, Finland formed the study population. They reported 589 former and 2092 subsequent fractures. The hazard ratio (HR), with 95% confidence interval (CI), of a subsequent fracture was 1.9 (1.6-2.3) in women with the history of a former fracture compared with women without such a history. A former low-energy wrist fracture was related to subsequent low-energy wrist [HR = 3.7 (2.0-6.8)] and high-energy nonwrist [HR = 2.4 (1.3-4.4)] fractures, whereas former high-energy nonwrist fractures were related only to subsequent high-energy nonwrist [HR = 2.8 (1.9-4.1)] but not to low-energy wrist [HR = 0.7 (0.3-1.8)] fractures. The analysis of bone mineral density (BMD) data of a subsample of premenopausal women who underwent dual x-ray absorptiometry (DXA) during 1989-91 revealed that those with a wrist fracture due to a fall on the same level at the age of 20-34 recorded 6.5% lower spinal (P = 0.140) and 10.5% lower femoral (P = 0.026) BMD than nonfractured women, whereas the corresponding differences for women with a former nonwrist fracture due to high-energy trauma were -1.8% (P = 0.721) and -2.4% (P = 0. 616), respectively. Our results suggest that an early premenopausal, low-energy wrist fracture is an indicator of low peak BMD which predisposes to subsequent fractures in general, whereas early high-energy fractures are mainly indicators of other and more specific extraskeletal factors which mainly predispose to same types of subsequent fractures only.

  9. Suppressed Charmed B Decay

    Energy Technology Data Exchange (ETDEWEB)

    Snoek, Hella Leonie [Vrije Univ., Amsterdam (Netherlands)

    2009-06-02

    This thesis describes the measurement of the branching fractions of the suppressed charmed B0 → D*- a0+ decays and the non-resonant B0 → D*- ηπ+ decays in approximately 230 million Υ(4S) → B$\\bar{B}$ events. The data have been collected with the BABAR detector at the PEP-II B factory at the Stanford Linear Accelerator Center in California. Theoretical predictions of the branching fraction of the B0 → D*- a{sub 0}+ decays show large QCD model dependent uncertainties. Non-factorizing terms, in the naive factorization model, that can be calculated by QCD factorizing models have a large impact on the branching fraction of these decay modes. The predictions of the branching fractions are of the order of 10-6. The measurement of the branching fraction gives more insight into the theoretical models. In general a better understanding of QCD models will be necessary to conduct weak interaction physics at the next level. The presence of CP violation in electroweak interactions allows the differentiation between matter and antimatter in the laws of physics. In the Standard Model, CP violation is incorporated in the CKM matrix that describes the weak interaction between quarks. Relations amongst the CKM matrix elements are used to present the two relevant parameters as the apex of a triangle (Unitarity Triangle) in a complex plane. The over-constraining of the CKM triangle by experimental measurements is an important test of the Standard Model. At this moment no stringent direct measurements of the CKM angle γ, one of the interior angles of the Unitarity Triangle, are available. The measurement of the angle γ can be performed using the decays of neutral B mesons. The B0 → D*- a0+ decay is sensitive to the angle γ and, in comparison to the current decays that are being employed, could significantly

  10. External fixation of tibial pilon fractures and fracture healing.

    Science.gov (United States)

    Ristiniemi, Jukka

    2007-06-01

    Distal tibial fractures are rare and difficult to treat because the bones are subcutaneous. External fixation is commonly used, but the method often results in delayed union. The aim of the present study was to find out the factors that affect fracture union in tibial pilon fractures. For this purpose, prospective data collection of tibial pilon fractures was carried out in 1998-2004, resulting in 159 fractures, of which 83 were treated with external fixation. Additionally, 23 open tibial fractures with significant > 3 cm bone defect that were treated with a staged method in 2000-2004 were retrospectively evaluated. The specific questions to be answered were: What are the risk factors for delayed union associated with two-ring hybrid external fixation? Does human recombinant BMP-7 accelerate healing? What is the role of temporary ankle-spanning external fixation? What is the healing potential of distal tibial bone loss treated with a staged method using antibiotic beads and subsequent autogenous cancellous grafting compared to other locations of the tibia? The following risk factors for delayed healing after external fixation were identified: post-reduction fracture gap of >3 mm and fixation of the associated fibula fracture. Fracture displacement could be better controlled with initial temporary external fixation than with early definitive fixation, but it had no significant effect on healing time, functional outcome or complication rate. Osteoinduction with rhBMP-7 was found to accelerate fracture healing and to shorten the sick leave. A staged method using antibiotic beads and subsequent autogenous cancellous grafting proved to be effective in the treatment of tibial bone loss. Healing potential of the bone loss in distal tibia was at least equally good as in other locations of the tibia.

  11. Rock fracture processes in chemically reactive environments

    Science.gov (United States)

    Eichhubl, P.

    2015-12-01

    Rock fracture is traditionally viewed as a brittle process involving damage nucleation and growth in a zone ahead of a larger fracture, resulting in fracture propagation once a threshold loading stress is exceeded. It is now increasingly recognized that coupled chemical-mechanical processes influence fracture growth in wide range of subsurface conditions that include igneous, metamorphic, and geothermal systems, and diagenetically reactive sedimentary systems with possible applications to hydrocarbon extraction and CO2 sequestration. Fracture processes aided or driven by chemical change can affect the onset of fracture, fracture shape and branching characteristics, and fracture network geometry, thus influencing mechanical strength and flow properties of rock systems. We are investigating two fundamental modes of chemical-mechanical interactions associated with fracture growth: 1. Fracture propagation may be aided by chemical dissolution or hydration reactions at the fracture tip allowing fracture propagation under subcritical stress loading conditions. We are evaluating effects of environmental conditions on critical (fracture toughness KIc) and subcritical (subcritical index) fracture properties using double torsion fracture mechanics tests on shale and sandstone. Depending on rock composition, the presence of reactive aqueous fluids can increase or decrease KIc and/or subcritical index. 2. Fracture may be concurrent with distributed dissolution-precipitation reactions in the hostrock beyond the immediate vicinity of the fracture tip. Reconstructing the fracture opening history recorded in crack-seal fracture cement of deeply buried sandstone we find that fracture length growth and fracture opening can be decoupled, with a phase of initial length growth followed by a phase of dominant fracture opening. This suggests that mechanical crack-tip failure processes, possibly aided by chemical crack-tip weakening, and distributed solution-precipitation creep in the

  12. Pediatric mandibular fractures.

    Science.gov (United States)

    Schweinfurth, J M; Koltai, P J

    1998-01-01

    Over the last 20 years, a revolution in the management of facial fractures has taken place. Refinements in biocompatible materials of great delicacy and strength along with advances in our understanding of biomechanics of the face, have rendered complex injuries consistently amenable to accurate 3-dimensional reconstruction. Furthermore, with the availability of education in the techniques of internal rigid fixation, these advanced techniques have become routine practice in adults. However, the suitability of rigid internal fixation for children remains controversial. There are many concerns about the effect of implanted hardware in the mandible of a growing child. In addition, some evidence suggests that the elevation of functional matrix off of bone may result in alterations in development. The goal is to restore the underlying bony architecture to its pre-injury position in a stable fashion, with a minimal of aesthetic and functional impairment. However, in children the treatment of bony injuries is most easily accomplished by techniques that may adversely effect craniofacial development. While it is not entirely possible to resolve this dilemma, there exists an extensive body of experimental and clinical information on the appropriate management of pediatric mandibular fractures which can be used to formulate a rational treatment plan for most cases. This paper presents an overview of the contemporary understanding and application of these treatment principles.

  13. Hydraulic fracturing proppants

    Directory of Open Access Journals (Sweden)

    V. P. P. de Campos

    Full Text Available Abstract Hydrocarbon reservoirs can be classified as unconventional or conventional depending on the oil and gas extraction difficulty, such as the need for high-cost technology and techniques. The hydrocarbon extraction from bituminous shale, commonly known as shale gas/oil, is performed by using the hydraulic fracturing technique in unconventional reservoirs where 95% water, 0.5% of additives and 4.5% of proppants are used. Environmental problems related to hydraulic fracturing technique and better performance/development of proppants are the current challenge faced by companies, researchers, regulatory agencies, environmentalists, governments and society. Shale gas is expected to increase USA fuel production, which triggers the development of new proppants and technologies of exploration. This paper presents a review of the definition of proppants, their types, characteristics and situation in the world market and information about manufacturers. The production of nanoscale materials such as anticorrosive and intelligent proppants besides proppants with carbon nanotubes is already carried out on a scale of tonnes per year in Belgium, Germany and Asia countries.

  14. Fracture induced electromagnetic radiation

    International Nuclear Information System (INIS)

    Frid, V; Rabinovitch, A; Bahat, D

    2003-01-01

    In our laboratory, we combine accurate electromagnetic radiation (EMR) measurements during fracture of rocks (carbonate and igneous) and transparent materials (glass, PMMA and glass ceramics) with careful fractographic methods. A critical analysis of experimental observations, accumulated here during the last decade together with supporting material from the works of other authors are used in this study to demonstrate the failure of all current models to explain the properties of EMR arising from fracture. The basic elements of a new model are proposed. These are (a) the EMR amplitude increases as long as the crack continues to grow, since new atomic bonds are severed and their contribution is added to the EMR. As a result, the atoms on both sides of the bonds are moved to 'non-equilibrium' positions relative to their steady state ones and begin to oscillate collectively in a manner similar to Debye model bulk oscillations - 'surface vibrational optical waves'; (b) when the crack halts, the waves and the EMR pulse amplitude decay by relaxation. These basic elements are already enough to describe the characteristics of the experimentally obtained isolated individual EMR pulses. These characteristics include the shape of the EMR pulse envelope, and the frequency, time duration and rise - fall time of the pulse

  15. Fracture induced electromagnetic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Frid, V [Geological and Environmental Sciences Department, Deichmann Rock Mechanics Laboratory of the Negev, Ben Gurion University of the Negev, Beer Sheva (Israel); Rabinovitch, A [Physics Department, Deichmann Rock Mechanics Laboratory of the Negev, Ben Gurion University of the Negev, Beer Sheva (Israel); Bahat, D [Geological and Environmental Sciences Department, Deichmann Rock Mechanics Laboratory of the Negev, Ben Gurion University of the Negev, Beer Sheva (Israel)

    2003-07-07

    In our laboratory, we combine accurate electromagnetic radiation (EMR) measurements during fracture of rocks (carbonate and igneous) and transparent materials (glass, PMMA and glass ceramics) with careful fractographic methods. A critical analysis of experimental observations, accumulated here during the last decade together with supporting material from the works of other authors are used in this study to demonstrate the failure of all current models to explain the properties of EMR arising from fracture. The basic elements of a new model are proposed. These are (a) the EMR amplitude increases as long as the crack continues to grow, since new atomic bonds are severed and their contribution is added to the EMR. As a result, the atoms on both sides of the bonds are moved to 'non-equilibrium' positions relative to their steady state ones and begin to oscillate collectively in a manner similar to Debye model bulk oscillations - 'surface vibrational optical waves'; (b) when the crack halts, the waves and the EMR pulse amplitude decay by relaxation. These basic elements are already enough to describe the characteristics of the experimentally obtained isolated individual EMR pulses. These characteristics include the shape of the EMR pulse envelope, and the frequency, time duration and rise - fall time of the pulse.

  16. Osteoporosis, Fractures, and Diabetes

    Directory of Open Access Journals (Sweden)

    Peter Jackuliak

    2014-01-01

    Full Text Available It is well established that osteoporosis and diabetes are prevalent diseases with significant associated morbidity and mortality. Patients with diabetes mellitus have an increased risk of bone fractures. In type 1 diabetes, the risk is increased by ∼6 times and is due to low bone mass. Despite increased bone mineral density (BMD, in patients with type 2 diabetes the risk is increased (which is about twice the risk in the general population due to the inferior quality of bone. Bone fragility in type 2 diabetes, which is not reflected by bone mineral density, depends on bone quality deterioration rather than bone mass reduction. Thus, surrogate markers and examination methods are needed to replace the insensitivity of BMD in assessing fracture risks of T2DM patients. One of these methods can be trabecular bone score. The aim of the paper is to present the present state of scientific knowledge about the osteoporosis risk in diabetic patient. The review also discusses the possibility of problematic using the study conclusions in real clinical practice.

  17. Cough-induced rib fractures.

    Science.gov (United States)

    Sano, Atsushi; Tashiro, Ken; Fukuda, Tsutomu

    2015-10-01

    Occasionally, patients who complain of chest pain after the onset of coughing are diagnosed with rib fractures. We investigated the characteristics of cough-induced rib fractures. Between April 2008 and December 2013, 17 patients were referred to our hospital with chest pain after the onset of coughing. Rib radiography was performed, focusing on the location of the chest pain. When the patient had other signs and symptoms such as fever or persistent cough, computed tomography of the chest was carried out. We analyzed the data retrospectively. Rib fractures were found in 14 of the 17 patients. The age of the patients ranged from 14 to 86 years (median 39.5 years). Ten patients were female and 4 were male. Three patients had chronic lung disease. There was a single rib fracture in 9 patients, and 5 had two or more fractures. The middle and lower ribs were the most commonly involved; the 10th rib was fractured most frequently. Cough-induced rib fractures occur in every age group regardless of the presence or absence of underlying disease. Since rib fractures often occur in the lower and middle ribs, rib radiography is useful for diagnosis. © The Author(s) 2015.

  18. Mechanical properties of fracture zones

    International Nuclear Information System (INIS)

    Leijon, B.

    1993-05-01

    Available data on mechanical characteristics of fracture zones are compiled and discussed. The aim is to improve the basis for adequate representation of fracture zones in geomechanical models. The sources of data researched are primarily borehole investigations and case studies in rock engineering, involving observations of fracture zones subjected to artificial load change. Boreholes only yield local information about the components of fracture zones, i.e. intact rock, fractures and various low-strength materials. Difficulties are therefore encountered in evaluating morphological and mechanical properties of fracture zones from borehole data. Although often thought of as macroscopically planar features, available field data consistently show that fracture zones are characterized by geometrical irregularities such as thickness variations, surface undulation and jogs. These irregularities prevail on all scales. As a result, fracture zones are on all scales characterized by large, in-plane variation of strength- and deformational properties. This has important mechanical consequences in terms of non-uniform stress transfer and complex mechanisms of shear deformation. Field evidence for these findings, in particular results from the underground research laboratory in Canada and from studies of induced fault slip in deep mines, is summarized and discussed. 79 refs

  19. Diplopia and Orbital Wall Fractures

    NARCIS (Netherlands)

    Boffano, P.; Roccia, F.; Gallesio, C.; Karagozoglu, K.H.; Forouzanfar, T.

    2014-01-01

    Diplopia is a symptom that is frequently associated with orbital wall fractures. The aim of this article was to present the incidence and patterns of diplopia after orbital wall blow-out fractures in 2 European centers, Turin and Amsterdam, and to identify any correlation between this symptom and

  20. Diplopia and orbital wall fractures

    NARCIS (Netherlands)

    Boffano, P.; Roccia, F.; Gallesio, C.; Karagozoglu, K.H.; Forouzanfar, T.

    2014-01-01

    Diplopia is a symptom that is frequently associated with orbital wall fractures. The aim of this article was to present the incidence and patterns of diplopia after orbital wall blow-out fractures in 2 European centers, Turin and Amsterdam, and to identify any correlation between this symptom and

  1. Mathematical modelling of fracture hydrology

    International Nuclear Information System (INIS)

    Herbert, A.W.; Hodgkinson, D.P.; Lever, D.A.; Robinson, P.C.; Rae, J.

    1985-06-01

    This report summarises the work performed between January 1983 and December 1984 for the CEC/DOE contract 'Mathematical Modelling of Fracture Hydrology', under the following headings: 1) Statistical fracture network modelling, 2) Continuum models of flow and transport, 3) Simplified models, 4) Analysis of laboratory experiments and 5) Analysis of field experiments. (author)

  2. Ankle Fractures: The Operative Outcome

    Directory of Open Access Journals (Sweden)

    Ahmad Hafiz Z

    2011-03-01

    Full Text Available Ankle fractures are commonly seen in orthopaedic practice. This retrospective study of patients with ankle fractures who underwent surgical treatment in our institution from January 2000 to December 2003 was undertaken to analyze the common causes and patterns of ankle fractures; and the functional outcome of operative treatment for these fractures. Eighty patients were identified and reviewed. There were 65 male (81.3% and 15 female patients (18.7% with age ranging from 13 to 71 years old (mean, 32.3y. Common causes of ankle fractures were trauma (especially motor vehicle accidents, sports injuries and the osteoporotic bones in the elderly. Weber C (64.0% was the most common pattern of fracture at presentation. The most common operative treatment for ankle fractures was open reduction and internal fixation (73 patients, 91.2%. Excellent and good outcomes were achieved in 93.8% of cases when measured using the Olerud and Molander scoring system for foot and ankle. In conclusion, operative treatment for ankle fractures restores sufficient stability and allowed mobility of the ankle joint.

  3. Isolated Transverse Sacrum Fracture: A Case Report

    Directory of Open Access Journals (Sweden)

    Cemil Kavalci

    2011-01-01

    Full Text Available Sacral fracture commonly results from high-energy trauma. Most insufficiency fractures of the sacrum are seen in women after the age of 70. Fractures of the sacrum are rare and generally combined with a concomitant pelvic fracture. Transverse sacral fractures are even less frequent which constitute only 3–5% of all sacral fractures. This type of fractures provide a diagnostic challenge. We report a unique case of isolated transverse fracture of sacrum in a young man sustained low-energy trauma. The patient presented to our emergency department after several hours of injury, and diagnosed by clinical features and roentgenogram findings.

  4. Fracture mechanisms and fracture control in composite structures

    Science.gov (United States)

    Kim, Wone-Chul

    Four basic failure modes--delamination, delamination buckling of composite sandwich panels, first-ply failure in cross-ply laminates, and compression failure--are analyzed using linear elastic fracture mechanics (LEFM) and the J-integral method. Structural failures, including those at the micromechanical level, are investigated with the aid of the models developed, and the critical strains for crack propagation for each mode are obtained. In the structural fracture analyses area, the fracture control schemes for delamination in a composite rib stiffener and delamination buckling in composite sandwich panels subjected to in-plane compression are determined. The critical fracture strains were predicted with the aid of LEFM for delamination and the J-integral method for delamination buckling. The use of toughened matrix systems has been recommended for improved damage tolerant design for delamination crack propagation. An experimental study was conducted to determine the onset of delamination buckling in composite sandwich panel containing flaws. The critical fracture loads computed using the proposed theoretical model and a numerical computational scheme closely followed the experimental measurements made on sandwich panel specimens of graphite/epoxy faceskins and aluminum honeycomb core with varying faceskin thicknesses and core sizes. Micromechanical models of fracture in composites are explored to predict transverse cracking of cross-ply laminates and compression fracture of unidirectional composites. A modified shear lag model which takes into account the important role of interlaminar shear zones between the 0 degree and 90 degree piles in cross-ply laminate is proposed and criteria for transverse cracking have been developed. For compressive failure of unidirectional composites, pre-existing defects play an important role. Using anisotropic elasticity, the stress state around a defect under a remotely applied compressive load is obtained. The experimentally

  5. Radiographic evaluation of maxillofacial fractures

    International Nuclear Information System (INIS)

    Litwan, M.; Fliegel, C.

    1986-01-01

    The course and configuration of typical maxillofacial fractures (type Le Fort I-III) and lateral maxillary fractures including the zygomatic arch were reconstructed in detail by application of barium paste on a bony skull and radiogrpahs in standard projections were performed and evaluated. It was obvious from the resulting radiographs that for most maxillofacial fractures a half axial or Water's view was most helpful. Lateral views only give additional information when there is a considerable degree of dislocation of fragments. Comparison with a prediatric skull of 8 years of age demonstrated that fractures of the zygomatic arch in this age group cannot be demonstrated by the typical submento-vertical view, but are shown on a Towne projection. The radiographic appearance of important maxillofacial fractures is demonstrated. The necessity of further studies in cases where reconstructive surgery appears necessary is discussed and CT rather then conventional tomography is advocated. (orig.) [de

  6. Collagen turnover after tibial fractures

    DEFF Research Database (Denmark)

    Joerring, S; Krogsgaard, M; Wilbek, H

    1994-01-01

    Collagen turnover after tibial fractures was examined in 16 patients with fracture of the tibial diaphysis and in 8 patients with fracture in the tibial condyle area by measuring sequential changes in serological markers of turnover of types I and III collagen for up to 26 weeks after fracture....... The markers were the carboxy-terminal extension peptide of type I procollagen (PICP), the amino-terminal extension peptide of type III procollagen (PIIINP), and the pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP). The latter is a new serum marker of degradation of type I...... collagen. A group comparison showed characteristic sequential changes in the turnover of types I and III collagen in fractures of the tibial diaphysis and tibial condyles. The turnover of type III collagen reached a maximum after 2 weeks in both groups. The synthesis of type I collagen reached a maximum...

  7. Computer simulation of ductile fracture

    International Nuclear Information System (INIS)

    Wilkins, M.L.; Streit, R.D.

    1979-01-01

    Finite difference computer simulation programs are capable of very accurate solutions to problems in plasticity with large deformations and rotation. This opens the possibility of developing models of ductile fracture by correlating experiments with equivalent computer simulations. Selected experiments were done to emphasize different aspects of the model. A difficult problem is the establishment of a fracture-size effect. This paper is a study of the strain field around notched tensile specimens of aluminum 6061-T651. A series of geometrically scaled specimens are tested to fracture. The scaled experiments are conducted for different notch radius-to-diameter ratios. The strains at fracture are determined from computer simulations. An estimate is made of the fracture-size effect

  8. Pathogenesis of osteoporotic hip fractures.

    Science.gov (United States)

    McClung, Michael R

    2003-01-01

    Osteoporosis is characterized late in the course of the disease by an increased risk of fracture, particularly in the elderly. It occurs in both sexes, affecting approximately 8 million women and 2 million men aged > or = 50 years (1). While low bone density is a predictor of fractures, it is not the only determinant of fracture risk. Other factors include advanced age, altered bone quality, a personal or family history of falls, frailty, poor eyesight, debilitating diseases, and high bone turnover. A diet with sufficient calcium and vitamin D is important to minimize bone loss and, along with regular exercise, to maintain muscle strength. Bisphosphonates have been shown to reduce the risk of hip fracture. For elderly patients, the use of hip protectors may be used as a treatment of last resort. Regardless of the age of the patient, individual patient risk factors must be considered to target appropriate treatment and prevent fracture.

  9. Noise suppression in surface microseismic data by τ-p transform

    Science.gov (United States)

    Forghani-Arani, Farnoush; Batzle, Mike; Behura, Jyoti; Willis, Mark; Haines, Seth; Davidson, Michael

    2013-01-01

    Surface passive seismic methods are receiving increased attention for monitoring changes in reservoirs during the production of unconventional oil and gas. However, in passive seismic data the strong cultural and ambient noise (mainly surface-waves) decreases the effectiveness of these techniques. Hence, suppression of surface-waves is a critical step in surface microseismic monitoring. We apply a noise suppression technique, based on the τ — p transform, to a surface passive seismic dataset recorded over a Barnett Shale reservoir undergoing a hydraulic fracturing process. This technique not only improves the signal-to-noise ratios of added synthetic microseismic events, but it also preserves the event waveforms.

  10. Relative Permeability of Fractured Rock

    Energy Technology Data Exchange (ETDEWEB)

    Mark D. Habana

    2002-06-30

    Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

  11. Fracture behavior of human molars.

    Science.gov (United States)

    Keown, Amanda J; Lee, James J-W; Bush, Mark B

    2012-12-01

    Despite the durability of human teeth, which are able to withstand repeated loading while maintaining form and function, they are still susceptible to fracture. We focus here on longitudinal fracture in molar teeth-channel-like cracks that run along the enamel sidewall of the tooth between the gum line (cemento-enamel junction-CEJ) and the occlusal surface. Such fractures can often be painful and necessitate costly restorative work. The following study describes fracture experiments made on molar teeth of humans in which the molars are placed under axial compressive load using a hard indenting plate in order to induce longitudinal cracks in the enamel. Observed damage modes include fractures originating in the occlusal region ('radial-median cracks') and fractures emanating from the margin of the enamel in the region of the CEJ ('margin cracks'), as well as 'spalling' of enamel (the linking of longitudinal cracks). The loading conditions that govern fracture behavior in enamel are reported and observations made of the evolution of fracture as the load is increased. Relatively low loads were required to induce observable crack initiation-approximately 100 N for radial-median cracks and 200 N for margin cracks-both of which are less than the reported maximum biting force on a single molar tooth of several hundred Newtons. Unstable crack growth was observed to take place soon after and occurred at loads lower than those calculated by the current fracture models. Multiple cracks were observed on a single cusp, their interactions influencing crack growth behavior. The majority of the teeth tested in this study were noted to exhibit margin cracks prior to compression testing, which were apparently formed during the functional lifetime of the tooth. Such teeth were still able to withstand additional loading prior to catastrophic fracture, highlighting the remarkable damage containment capabilities of the natural tooth structure.

  12. Suitability of ground penetrating radar for locating large fractures

    Energy Technology Data Exchange (ETDEWEB)

    Heikkinen, E. [Poeyry Finland Oy, Vantaa (Finland); Kantia, P. [Roadscanners Oy, Rovaniemi (Finland)

    2011-12-15

    Posiva Oy is responsible for preparation of final disposal of spent nuclear fuel in Olkiluoto. The knowledge about existing network of fractures is important for the safety and feasibility of the final repository. The bedrock properties essential for safety case are analysed in investigations of Rock Suitability Criteria (RSC). One subtask in RSC is avoidance of large (long) fractures adjacent to disposal holes. The long fractures have been defined in tunnel mapping to indicate tunnel cross-cutting features (TCF) or full perimeter intersections (FPI). Suitability of ground penetrating radar (GPR) method for locating large fractures was assessed. The assessment used data measured with 100 MHz and 270 MHz radar tool on ONKALO access tunnel right-hand wall, chainage 3344 - 3578 and on TKU-3 niche floor chainage 15 - 55 and 25 - 67 m. GPR images were processed to enhance reflections and suppress interference and diffractions. Images were placed on measurement position in 3D presentation software. The tunnel wall and floor mapping data was presented along with GPR images. A review of observed GPR reflections, and assessment of visibility of large fractures, was drawn on basis of 3D view examination. The GPR tool can detect reflections from cleaned and dry rock floor and wall. Depth of penetration is 8-12 m for 270 MHz antenna. The antenna has high resolution. Coupling on rock surface is good, which suppresses ringing and interference. Penetration is 20-24 m for 100 MHz antenna, which has a trade off of higher interference due to weaker contact to surface caused by large antenna. There are observed many kind of reflecting surfaces and diffractors in the images, like for example lithological contacts and high grade shearing, and also fractures. Proper manner to apply the method is to use raw and processed images during geological mapping to confirm the origin of reflections. Reflections deemed to be caused by fractures are useful to be compiled to 3D model objects. The

  13. Suitability of ground penetrating radar for locating large fractures

    International Nuclear Information System (INIS)

    Heikkinen, E.; Kantia, P.

    2011-12-01

    Posiva Oy is responsible for preparation of final disposal of spent nuclear fuel in Olkiluoto. The knowledge about existing network of fractures is important for the safety and feasibility of the final repository. The bedrock properties essential for safety case are analysed in investigations of Rock Suitability Criteria (RSC). One subtask in RSC is avoidance of large (long) fractures adjacent to disposal holes. The long fractures have been defined in tunnel mapping to indicate tunnel cross-cutting features (TCF) or full perimeter intersections (FPI). Suitability of ground penetrating radar (GPR) method for locating large fractures was assessed. The assessment used data measured with 100 MHz and 270 MHz radar tool on ONKALO access tunnel right-hand wall, chainage 3344 - 3578 and on TKU-3 niche floor chainage 15 - 55 and 25 - 67 m. GPR images were processed to enhance reflections and suppress interference and diffractions. Images were placed on measurement position in 3D presentation software. The tunnel wall and floor mapping data was presented along with GPR images. A review of observed GPR reflections, and assessment of visibility of large fractures, was drawn on basis of 3D view examination. The GPR tool can detect reflections from cleaned and dry rock floor and wall. Depth of penetration is 8-12 m for 270 MHz antenna. The antenna has high resolution. Coupling on rock surface is good, which suppresses ringing and interference. Penetration is 20-24 m for 100 MHz antenna, which has a trade off of higher interference due to weaker contact to surface caused by large antenna. There are observed many kind of reflecting surfaces and diffractors in the images, like for example lithological contacts and high grade shearing, and also fractures. Proper manner to apply the method is to use raw and processed images during geological mapping to confirm the origin of reflections. Reflections deemed to be caused by fractures are useful to be compiled to 3D model objects. The

  14. Mortality Following Periprosthetic Proximal Femoral Fractures Versus Native Hip Fractures.

    Science.gov (United States)

    Boylan, Matthew R; Riesgo, Aldo M; Paulino, Carl B; Slover, James D; Zuckerman, Joseph D; Egol, Kenneth A

    2018-04-04

    The number of periprosthetic proximal femoral fractures is expected to increase with the increasing prevalence of hip arthroplasties. While native hip fractures have a well-known association with mortality, there are currently limited data on this outcome among the subset of patients with periprosthetic proximal femoral fractures. Using the New York Statewide Planning and Research Cooperative System, we identified patients from 60 to 99 years old who were admitted to a hospital in the state with a periprosthetic proximal femoral fracture (n = 1,655) or a native hip (femoral neck or intertrochanteric) fracture (n = 97,231) between 2006 and 2014. Within the periprosthetic fracture cohort, the indication for the existing implant was not available in the data set. We used mixed-effects regression models to compare mortality at 1 and 6 months and 1 year for periprosthetic compared with native hip fractures. The risk of mortality for patients who sustained a periprosthetic proximal femoral fracture was no different from that for patients who sustained a native hip fracture at 1 month after injury (3.2% versus 4.6%; odds ratio [OR], 0.90; 95% confidence interval [CI], 0.68 to 1.19; p = 0.446), but was lower at 6 months (3.8% versus 6.5%; OR, 0.74; 95% CI, 0.57 to 0.95; p = 0.020) and 1 year (9.7% versus 15.9%; OR, 0.71; 95% CI, 0.60 to 0.85; p accounting for age and comorbidities. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

  15. A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures

    Directory of Open Access Journals (Sweden)

    Gultekin Gulbahar

    2015-01-01

    Full Text Available First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare entity.

  16. A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures

    OpenAIRE

    Gulbahar, Gultekin; Kaplan, Tevfik; Turker, Hasan Bozkurt; Gundogdu, Ahmet Gokhan; Han, Serdar

    2015-01-01

    First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare en...

  17. A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures.

    Science.gov (United States)

    Gulbahar, Gultekin; Kaplan, Tevfik; Turker, Hasan Bozkurt; Gundogdu, Ahmet Gokhan; Han, Serdar

    2015-01-01

    First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare entity.

  18. Probabilistic fracture finite elements

    Science.gov (United States)

    Liu, W. K.; Belytschko, T.; Lua, Y. J.

    1991-05-01

    The Probabilistic Fracture Mechanics (PFM) is a promising method for estimating the fatigue life and inspection cycles for mechanical and structural components. The Probability Finite Element Method (PFEM), which is based on second moment analysis, has proved to be a promising, practical approach to handle problems with uncertainties. As the PFEM provides a powerful computational tool to determine first and second moment of random parameters, the second moment reliability method can be easily combined with PFEM to obtain measures of the reliability of the structural system. The method is also being applied to fatigue crack growth. Uncertainties in the material properties of advanced materials such as polycrystalline alloys, ceramics, and composites are commonly observed from experimental tests. This is mainly attributed to intrinsic microcracks, which are randomly distributed as a result of the applied load and the residual stress.

  19. Fracture flow code

    International Nuclear Information System (INIS)

    Dershowitz, W; Herbert, A.; Long, J.

    1989-03-01

    The hydrology of the SCV site will be modelled utilizing discrete fracture flow models. These models are complex, and can not be fully cerified by comparison to analytical solutions. The best approach for verification of these codes is therefore cross-verification between different codes. This is complicated by the variation in assumptions and solution techniques utilized in different codes. Cross-verification procedures are defined which allow comparison of the codes developed by Harwell Laboratory, Lawrence Berkeley Laboratory, and Golder Associates Inc. Six cross-verification datasets are defined for deterministic and stochastic verification of geometric and flow features of the codes. Additional datasets for verification of transport features will be documented in a future report. (13 figs., 7 tabs., 10 refs.) (authors)

  20. Experimental and Numerical Studies on Development of Fracture Process Zone (FPZ) in Rocks under Cyclic and Static Loadings

    Science.gov (United States)

    Ghamgosar, M.; Erarslan, N.

    2016-03-01

    The development of fracture process zones (FPZ) in the Cracked Chevron Notched Brazilian Disc (CCNBD) monsonite and Brisbane tuff specimens was investigated to evaluate the mechanical behaviour of brittle rocks under static and various cyclic loadings. An FPZ is a region that involves different types of damage around the pre-existing and/or stress-induced crack tips in engineering materials. This highly damaged area includes micro- and meso-cracks, which emerge prior to the main fracture growth or extension and ultimately coalescence to macrofractures, leading to the failure. The experiments and numerical simulations were designed for this study to investigate the following features of FPZ in rocks: (1) ligament connections and (2) microcracking and its coalescence in FPZ. A Computed Tomography (CT) scan technique was also used to investigate the FPZ behaviour in selected rock specimens. The CT scan results showed that the fracturing velocity is entirely dependent on the appropriate amount of fracture energy absorbed in rock specimens due to the change of frequency and amplitudes of the dynamic loading. Extended Finite Element Method (XFEM) was used to compute the displacements, tensile stress distribution and plastic energy dissipation around the propagating crack tip in FPZ. One of the most important observations, the shape of FPZ and its extension around the crack tip, was made using numerical and experimental results, which supported the CT scan results. When the static rupture and the cyclic rupture were compared, the main differences are twofold: (1) the number of fragments produced is much greater under cyclic loading than under static loading, and (2) intergranular cracks are formed due to particle breakage under cyclic loading compared with smooth and bright cracks along cleavage planes under static loading.