bluuebunny/crossref_metadata_2025 huggingface dataset:
Industrial Solid Waste Management for the Eastern Seaboard—Thailand's First Systematic Approach to the Problem
Authors: Ludwig HF , Evans JW , Tridech S
Published: December 2008

Accelerating population growth, urbanization, and industrialization in Thailand are creating unprecedented problems requiring government intervention for achieving systematic planning and growth of existing and new urban centers. The first such regional planning project in Thailand, carried out under the sponsorship of the National Economic and Social Development Board in 1981–1982, was focused on the Eastern Seaboard, the coastal zone on the Gulf of Thailand to the southeast of Bangkok. Because of the recent development of major natural gas fields in the gulf, the Eastern Seaboard region seems destined to become a new regional urban-industrial center. The planning project resulted in preparation of a comprehensive plan for guiding continuing development in the region, with particular attention to industrial development and environmental pollution control. Preliminary concepts were developed for management of industrial solid wastes at the various urban growth centers in the region, including bulk or nonhazardous wastes and hazardous wastes. Both conventional and innovative practices, adapted to the Eastern Seaboard situation, are utilized.
A Review of Chevron-Notched Fracture Specimens
Authors: Newman JC
Published: December 2008

This paper reviews the historical development of chevron-notched fracture specimens; it also compares stress-intensity factors and load line displacement solutions that have been proposed for some of these specimens. The review covers the original bend-bar configurations up to the present day short-rod and bar specimens. In particular, the results of a recent analytical round robin that was conducted by an ASTM Task Group on Chevron-Notched Specimens are presented.

In the round robin, three institutions calculated stress-intensity factors for either the chevron-notched round-rod or square-bar specimens. These analytical solutions were compared among themselves, and then among the various experimental solutions that have been proposed for these specimens. The experimental and analytical stress-intensity factor solutions that were obtained from the compliance method agreed within 3% for both specimens. An assessment of the consensus stress-intensity factor (compliance) solution for these specimens is made.

The stress-intensity factor solutions proposed for three- and four-point bend chevron-notched specimens are also reviewed. On the basis of this review, the bend-bar configurations need further experimental and analytical calibrations.

The chevron-notched rod, bar, and bend-bar specimens were developed to determine fracture toughness of brittle materials, materials that exhibit flat or nearly flat crack-growth resistance curves. The problems associated with using such specimens for materials that have a rising crack-growth resistance curve are reviewed.
Midrange Fatigue Crack Growth Data Correlations for Structural Alloys at Room and Cryogenic Temperatures
Authors: Tobler RL , Cheng Y-W
Published: December 2008

Fatigue crack growth rate data for pure metals, structural alloys, and welds at temperatures from 295 to 4 K are selectively reviewed. The data for more than 200 material and temperature combinations are discussed in terms of the parameters C and n for the midrange of the da/dN-versus-ΔK curve. Fatigue resistance varies greatly among the different alloy classes and crystal structure types, especially at extreme cryogenic temperatures, where alternative failure mechanisms emerge. Good general correlations were achieved on the basis of Young's modulus, fracture toughness, and empirical equations relating C and n for each alloy class.
Cyclic Softening and Hardening of Austenitic Steels at Low Temperatures
Authors: Shibata K , Kishimoto Y , Namura N , Fujita T
Published: December 2008

The fatigue behavior of austenitic stainless steels and nonmagnetic high-manganese steels has been investigated in ambient air, liquid nitrogen, and liquid helium. Particular attention was paid to the influence of nitrogen and carbon additions. Low-cyclic fatigue tests were carried out under tension-compression at a strain rate of 3 × 10−3 s−1. In all the stainless steels, cyclic softening following initial hardening was observed at lower strain amplitudes; the softening was remarkably enhanced by the addition of nitrogen. Solute carbon also had a similar effect, although to a lesser degree than nitrogen. In the high-manganese steels, the amount of softening was significantly affected by manganese content. The effect of the interstitial atoms on the softening was smaller in the 32% manganese series of steels than in the stainless steels. A decrease in the testing temperature increased the softening in both series of steels. Planar structures or less-tangled structures of dislocations were formed, and cellular structures were scarcely observed in all the steels showing the remarkable softening. The tendency of dislocations to form these less-tangled dislocation arrangements, and the softening and hardening behavior of the steels, could not be explained as an effect of stacking fault energy alone, but could be qualitatively interpreted by assuming the existence of some ordering between substitutional and interstitial atoms in the as-solution-treated steels. The significant softening seemed to increase fatigue life under the strain-controlled condition.
Effect of Low Temperature on Fatigue and Fracture Properties of Ti-5Al-2.5Sn(ELI) for Use in Engine Components
Authors: Ryder JT , Witzell WE
Published: December 2008

The results of an experimental investigation designed to obtain the material property data necessary to establish the salient characteristics of a Ti-5Al-2.5Sn(ELI) alloy for use in a fuel pump impellor at cryogenic temperatures are described. Tension, fracture toughness, and fatigue crack propagation data were obtained from pancake forgings at room temperature in laboratory air and at 20 K (−423°F) in liquid hydrogen. Experiments were performed on coupons of three different orientations, from different forgings, and from different forging lots. The effect of frequency (0.1 and 10 Hz) and R ratio (+0.05 and +0.5) on crack propagation was evaluated.

Tensile strength significantly increased at cryogenic temperatures compared to room temperature, percent elongation had a minor reduction, percent reduction in area significantly decreased, and modulus increased approximately 8%. Fracture toughness showed a significant reduction at cryogenic temperatures, as expected. A difference in toughness caused by orientation of as much as 25% was observed, despite the lack of any significant differences in material texture. The fatigue crack growth rate of this alloy showed a remarkable lack of sensitivity to the various experimental conditions. Crack orientation effects were minimal, although there were some small shifts in threshold. The two different forging lots resulted in a small shift in growth rate. No effect of frequency was found at any combination of R ratio and temperature. A load ratio effect was observed, but this expected result was manifested only by a small shift to higher rates at R = 0.5. No effect of temperature on fatigue crack propagation was observed from threshold (∼10−8 m/cycle [∼4 × 10−7 in./cycle]) to 44 MPa √m (40 ksi √in.) (∼1 × 10−6 m/cycle [∼4 × 10−5 in./cycle]). Above this level the observed difference in growth rate was due to the lower fracture toughness at 20 K (−423°F).
Effect of Temperature on the Fatigue and Fracture Properties of 7475-T761 Aluminum
Authors: Cox JM , Pettit DE , Langenbeck SL
Published: December 2008

The effect of low-temperature toughness degradation on damage tolerance and life analysis methodology is discussed. Spectrum fatigue and fatigue crack growth tests were conducted and life predictions made on 7475-T761 aluminum. The retardation behavior was determined by conducting constant K single overload fatigue crack growth tests. The low-temperature environment (−54°C[−65°F]) improved the life of fatigue and fatigue crack growth tests subjected to several loading spectra. This may be partially attributable to stronger retardation effects at low temperatures. It is concluded that low temperature may be a factor in damage tolerance and life analysis only under certain conditions.
Variable-Amplitude Fatigue Crack Initiation and Growth of Five Carbon or Low-Alloy Cast Steels at Room and Low Climatic Temperatures
Authors: Stephens RI , Fatemi A , Lee HW , Lee SG , Vacas-Oleas C , Wang CM
Published: December 2008

Five common cast steels were subjected to SAE transmission history at room temperature and three low climatic temperatures using an as-drilled keyhole notched compact specimen. The three low temperatures were −34, −45, and −60°C. These temperatures were both above and below nil ductility transition temperatures. Three fatigue criteria were specifically monitored: crack initiation defined by the first visible surface crack Δa equal to 0.25 mm, Δa equal to 2.5 mm, and final fracture. All low-temperature total fatigue lives were equal to or better than at room temperature for four of the five cast steels. All steels exhibited crack initiation lives at low temperatures equal to or better than at room temperature. Fatigue crack growth life tended to increase as the temperature was lowered, and then this trend reversed. Scanning electron fractographic analysis showed all ductile type fatigue crack growth mechanisms above or below the nil ductility transition temperature.
Effect of End-Tab Design on Tension Specimen Stress Concentrations
Authors: Cunningham ME , Schoultz SV , Toth JM
Published: December 2008

An analytical and experimental study was performed to evaluate geometrical and material parameter effects on the stress concentrations of tension specimen end-tab design. The parameters were constrained to those falling within the options set forth in the ASTM Test for Tensile Properties of Fiber Resin Composites (D 3039-76). Geometrical parameters included tab angle, tab thickness, cutoff thickness, tab length, and adhesive thickness. Material parameters included tab material and adhesive material. The tension specimen and thickness were held constant.
Measurements of Dynamic Properties of Rock at Elevated Temperatures and Pressures
Authors: Christensen NI
Published: December 2008

Measurements of dynamic properties of rock at high temperatures and pressures have many applications to geology and solid earth geophysics. Elastic wave velocities are obtained from rock cylinders in which delay times are measured using a pulse transmission technique. The longitudinal and shear velocities and bulk densities allow the calculation of isotropic elastic moduli. Techniques and equipment used for measuring velocities as functions of confining pressure, pore pressure, and temperature are summarized.
Correcting Flexible Pavement Deficiencies: The Ontario Way
Authors: Chong GJ , Phang WA
Published: December 2008

Ontario emphasizes preservation of their highway system by carrying out maintenance activities aimed at prolonging the life of highway pavements. To make the maintenance task easier and more effective, a set of guidelines was developed that helps maintenance staff make the best decision, one that is most cost-effective and one that is made consistently by different maintenance staff. For the most part, the guidelines deal with short-term measures-deficiencies that have to be fixed right now, that is, corrective maintenance. But they can also be used to identify situations where preventive maintenance will affect the service life of the pavement. The guidelines contain the following elements: (1) identification process, (2) treatment selection, and (3) performance standard.

This paper describes our current practice of identifying and classifying a typical deficiency, selection of the most cost-effective treatment, the specifications for equipment and materials needed to carry out the treatment, and the proper work methods. As a typical example, this paper will describe flexible pavement crackings and cracks that are routed and sealed as the prescribed treatment.
Corrosion of Surgical Implant Alloys: A Few Basic Ideas
Authors: Greene ND
Published: December 2008

The corrosion processes occurring on surgically implanted alloys are reviewed. Crevice corrosion and other forms of attack observed on surgical implants are described. The theory, techniques and results of linear polarization corrosion rate measurements are discussed.
Corrosion-Fatigue Performance of Hip Nails: The Influence of Materials Selection and Design
Authors: Piehler HR , Portnoff MA , Sloter LE , Vegdahl EJ , Gilbert JL , Weber MJ
Published: December 2008

Corrosion-fatigue performance is evaluated for several Jewett-type hip nails of different design tested in Ringer's solution. Other devices of similar design fabricated from Type 316L stainless steel and Ti-6AI-4V are tested as well. Microstructural and fractographic analyses of all devices are also performed. Present results confirm initial observations that the corrosion-fatigue performance of large-plate Jewetts exceeds that of small-plate devices. Devices of similar design except for the placement of the proximal screw hole in a centered or offset position are evaluated; the latter devices improved corrosion-fatigue performance. Comparison of Jewetts of similar design reveals that the corrosion-fatigue performance of the Ti-6AI-4V devices markedly exceeds that of the Type 316L, even in the presence of substantial fretting and wear.
Retrieval Analysis of Total Joint Replacement Components: A Six-Year Experience
Authors: Wright TM , Burstein AH , Bartel DL
Published: December 2008

Total joint replacement components have been examined as part of an ongoing implant retrieval analysis program. Examination of 65 fractured metal femoral components from total hip replacements revealed that all were caused by a fatigue mechanism and that factors such as stem position, material defects, cement technique, patient weight and activity, and stem design played an important role. Metal components from total knee replacements faired better, except those from metal-on-metal constrained designs, which were subject to fracture and considerable wear. Ultrahigh molecular weight polyethylene components showed several modes of damage, including surface wear, permanent deformation, and fracture. Subjective damage grading of 75 acetabular and 57 tibial components revealed significant correlations with patient weight and implantation time.
Time/Toxicity Relationships in Short-Term Static, Dynamic, and Plug-Flow Bioassays
Authors: Bailey HC , Liu DHW , Javitz HA
Published: December 2008

In order to determine the efficacy of using data from 96-h acute bioassays for predicting toxicity associated with shorter exposure periods, a series of static, dynamic, and plug-flow bioassays were performed using bluegill as test organisms. Test chemicals included acrylonitrile, ammonia, chlorobenzene, chromic acid, copper sulfate, 2-ethoxyethylacetate, methylmethacrylate, sodium hydroxide, sulfuric acid, and xylene. Exposure durations ranged from 1 to 96 h. Regression techniques were used to develop time-toxicity curves to determine how well short-term toxicity could be predicted by 24 to 96 h data.

The results from these experiments indicate that data from 24 to 96-h exposure periods have limited use in predicting toxicity associated with shorter exposure periods, depending on the desired level of precision of the estimate. In extreme cases, the estimated LC50s ranged from twenty-fold below to three-fold above the observed LC50 values. In most cases, however, agreement between the estimated and actual LC50 values was much closer. While the usefulness of such mathematical predictors remains to be established, they could have merit in assessing the potential toxicity associated with single-event exposures such as chemical spills or runoff events.
The Acute Toxicity of Chlorine on Freshwater Organisms: Time-Concentration Relationships of Constant and Intermittent Exposures
Authors: Wang MP , Hanson SA
Published: December 2008

The effect of chlorine exposures on the survival of freshwater aquatic life is of major concern within many of the waterbodies in the United States. Continuous chlorine exposures are a typical result of effluent releases from wastewater treatment plants. Intermittent chlorine exposures are representative of the “blow down” antifouling procedure used for cooling towers in power plants.

The purpose of this paper is to present the derivation and resulting mathematical expressions for the time-concentration relationship of chlorine exposure and survival of freshwater aquatic organisms. Two topics will be discussed: the time-concentration toxicity relationship for constant chlorine exposures and the prediction from the constant exposure mathematical expressions of toxicity caused by intermittent exposures.

An extensive literature review provided the database from which mathematical time-concentration relationships were derived for constant chlorine exposures. Relationships were analyzed for individual species. The resistance of all the different species increased significantly from a 96-h exposure period to an 8-h exposure period.

The intermittent chlorine exposure tests differ not only in the frequency and duration of the chlorine dose but also in the geometric form of the dose application. A kinetic model, which accounted for these variabilities, was used to predict intermittent exposure mortality. The parameters of the model were obtained from the analysis of constant exposure results. In addition to predicting mortality resulting from variable exposure patterns, the kinetic model may be used to design appropriate test durations for intermittent chlorination experiments.
An Aquatic Hazard Assessment: Picloram
Authors: Mayes MA , Oliver GR
Published: December 2008

Picloram (4-amino-3,5,6-trichloropicolinic acid) exhibits herbicidal activities on broadleaf weeds and woody plants and is registered under the trademarks of TORDON®, GRAZON®, and AMDON® herbicides. It is an organic acid (pKa = 3.2); thus at environmental pH ranges it is usually found in the ionized anionic form. Other physicochemical characteristics of picloram are water solubility 430 mg/L and vapor pressure 6.16 × 10−7 mm mercury at 35°C. The rate of dissipation of picloram in soil is dependent on the application rate, soil type, and climate. Picloram is classified as having moderate mobility in soil; however, the runoff potential of picloram is normally limited to less than 5% of the applied chemical removed from the site in runoff waters.

Picloram is relatively nontoxic to freshwater fishes, with acute LC50 values for technical acid ranging from 4.3 mg/L for lake trout [Salvelinus namaycush (Walbaum)] to 55.3 mg/L for fathead minnows (Pimephales promelas Rafinesque). Freshwater invertebrates show similar susceptibility to technical picloram with acute LC50 values ranging from 27 mg/L for Gammarus lacustris Sars to 68.3 mg/L for Daphnia magna Straus. The most sensitive marine invertebrate tested is the eastern oyster [Crassostrea virginica (Gmelin)] with 18 < EC50 < 32 mg/L when exposed to a potassium salt formulation of picloram. Because of its relatively low toxicity to aquatic organisms and low potential for substantial quantities to enter the aquatic environment, picloram is not expected to present a hazard to the aquatic environment.
A Method to Avoid Crevice Corrosion in Electrochemical Determination of Pitting Potentials
Authors: Hakkarainen T
Published: December 2008

A test arrangement is described, where the electrolyte is brought into contact with the test surface along a multilayered textile tape. This method brings several advantages when compared to the common specimen holders, where part of the specimen surface is masked off by some insulating material. In the absence of crevices, there is no crevice corrosion. No special pretreatment of the test surface is required. Thus, various surface conditions can be tested, including as-received surfaces. The test surface need not be planar. Specimens like bars or weld beads can easily be tested. The desired surface can be selected for the test. The spatial orientation of the test surface can be chosen deliberately. The shape and size of the specimen can vary greatly, which makes the specimen preparation in most cases extremely easy.

The possible uses of the method are demonstrated by room temperature testing of stainless steel sheets and welds in sodium chloride solutions, as well as testing of prestressing steel wire in a saturated calcium hydroxide solution with various concentrations of sodium chloride. Both pit nucleation and repassivation potentials are determined using potentiokinetic techniques. The effects of some experimental variables are studied and discussed.
Void Swelling and Microstructural Change in Neutron Irradiated Type 316 Stainless Steel
Authors: Itoh M , Onose S , Yuhara S
Published: December 2008

Microstructural observations were made on cold-worked Type 316 stainless steel following fast neutron irradiation to a peak neutron fluence of 1.3 × 1027 n/m2 (E > 0.1 MeV) at temperatures from 400 to 620°C. The results show that nickel depletion in the matrix after neutron irradiation is related to the formation of phosphides and void swelling. Phosphorus in solution retards not only the recovery of dislocations but also the development of nickel- and silicon-rich phases, and this results in suppressing nickel depletion in the matrix and an extension of the transient regime in void swelling. Phosphides are formed during the transient regime at temperatures from 490 to 570°C. After phosphides are formed, retardation effects on both dislocation recovery and the formation of nickel- and silicon-rich phases are lost, and this leads to the onset of void swelling.
Neutron-Induced Swelling of Fe-Mn and Fe-Cr-Mn Austenitic Alloys
Authors: Garner FA , Brager HR
Published: December 2008

An effort is underway to explore the potential of Fe-Cr-Mn austenitic alloys as substitutes for Fe-Cr-Ni alloys in fusion reactors. This substitution is desired to achieve a reduced level of long-term radioactivity and thereby reduce the cost and safety hazards associated with disposal of reactor components at their end of life. Neutron-induced swelling data to 50 dpa are now available at 520°C for three reduced activation alloy series and for lower exposures at 420 and 600°C. These three series cover simple binary and ternary alloys, solute-modified ternaries, and a variety of commercially available Fe-Cr-Mn alloys. The swelling of these alloys is initially similar to that of Fe-Cr-Ni alloys but then changes in response to phase instabilities that develop in the Fe-Cr-Mn system.
The Influence of Both Major and Minor Element Composition on Void Swelling in Austenitic Steels
Authors: Garner FA , Kumar AS
Published: December 2008

Data on the neutron-induced swelling of simple Fe-Ni-Cr austenitic alloys are presented to show that there are three compositional regimes of swelling as a function of nickel content. The intermediate transition regime can be shifted to higher or lower nickel levels as a function of chromium content, various solutes, displacement rate, temperature, and helium level. Such shifts can preclude the observation of either the lower or upper nickel regime. The lower nickel regime is also obscured in ion bombardment studies because of factors that are atypical of the neutron environment.

Data are also presented to show the influence of silicon and phosphorus on the neutron-induced swelling of Fe-25Ni-15Cr and to demonstrate that the separate influence of each of these elements is more complex than previously observed. Similar complex trends have also been seen in ion bombardment experiments, but there are additional distortions relative to the neutron-induced behavior that arise from the interaction of these elements with point defect gradients.

A model is presented to show that the major effect of composition on swelling lies in its influence on void nucleation, operating primarily on the intermediate transition regime. Compositional variations thus appear as a “temperature shift” analogous to that associated with changes in displacement rate. This shift is due to the effect of each element on the vacancy supersaturation via their effect on either the equilibrium vacancy concentration or the effective vacancy diffusion coefficient.
Precipitate Evolution in Type 316 Stainless Steels Irradiated in EBR-II
Authors: Yang WJS
Published: December 2008

The irradiation temperature and fluence dependences of precipitates formed in Type 316 stainless steels with and without titanium have been studied for specimens irradiated over a fluence range of 3 × 1026 to 25 × 1026 n/m2 (E > 0.1 MeV) and a temperature range of 370 to 730°C. A precipitate formation diagram using irradiation temperature and fluence as the two coordinates is constructed. The composition of M6C is found to be irradiation temperature dependent. The composition of Laves is found to be both irradiation temperature and fluence dependent. The variable composition behavior of the precipitates, M6C and Laves, during irradiation is discussed in terms of nonequilibrium segregation and the radiation-induced off-stoichiometric characteristics of the precipitates.
Phase Transformations in Neutron-Irradiated Zircaloys
Authors: Chung HM
Published: December 2008

Microstructural evolution in Zircaloy-2 and -4 spent-fuel cladding specimens after three years of irradiation in commercial power reactors has been investigated by transmission and high-voltage electron microscopies. Two kinds of precipitates induced by the fastneutron irradiation in the reactors have been identified, that is, Zr3O and cubic-ZrO2 particles approximately 2 to 10 nm in size. By means of specimen tilting and dark-field stereomicroscopy, the bulk nature of the cubic-ZrO2 particles has been shown. The Zr(Fex,Cr1−x)2 and Zr2(Fex,Ni1−x) intermetallic precipitates normally present in the as-fabricated material virtually dissolved in the spent-fuel cladding specimens after a fast-neutron fluence of ∼4 × 1021 n/cm2 in the power reactors. The observed radiation-induced phase transformations are discussed in relation with the currently available understanding of the alloy characteristics.
Spinodal-like Decomposition and Swelling Induced by Ion Irradiation in Simple Fe-Ni and Fe-Ni-Cr Alloys
Authors: Dodd RA , Garner FA , Kai J-J , Lauritzen T , Johnston WG
Published: December 2008

A previously published correlation between the compositional dependence of neutron-induced swelling at high temperatures in Fe-Ni-Cr alloys and the development of compositional micro-oscillations has also been found in this study of swelling induced by 5-MeV Ni+ ion irradiation. The tendency toward decomposition is strongest in the 35 to 45% nickel range and diminishes in the range of 60 to 75% nickel. Chromium appears to play no role other than as a surrogate for iron. The scale of the micro-oscillation appears to be more sensitive to temperature than displacement rate. One consequence of this decomposition is the occasional formation of precipitate phases upon cooling after irradiation. In Fe-35Ni, cellular martensite is found to form after irradiation at 625, 675, and 725°C. In Fe-60Ni-15Cr irradiated at 625°C an ordered phase that may be Ni3(Fe,Cr) is sometimes formed. The fortuitous formation of these phases allows the visualization of the size and spacing of the compositional modulations.
Analysis of Flexural Fatigue Damage in Unidirectional Composites
Authors: Newaz GM
Published: December 2008

A flexural fatigue study of unidirectional E-glass/epoxy composite with 48 volume % glass fibers was undertaken (1) to understand and analyze the mechanisms of fatigue damage and (2) to evaluate the material degradation due to cyclic loading by monitoring the loss in stiffness. The fatigue tests were performed in the deflection-controlled mode with a sinusoidal waveform for a frequency of 3 Hz. The deflection-controlled testing mode was chosen to allow for decreased tendency toward hysteretic heating and to maintain controlled damage growth during fatigue cycling. Also, this testing mode minimizes the creep-fatigue interaction. Fatigue failure mechanisms in high and low deflection levels were found to be different. At high deflection levels, both matrix cracks and fiber breaks preferentially oriented at 90° to the fiber direction occurred simultaneously on the tensile side of the specimen, and out-of-plane fiber buckling was evident on the compression side, which eventually resulted in localized delamination. At low deflection levels, matrix cracking and fiber-matrix debonding were evident on the tensile surface. Fiber breakage was either not present or was very minimal. Compressive damage was not a concern at low deflection levels. The stiffness loss at high deflection cycling was rapid as opposed to a gradual decrease observed at low deflection cycling. The greater stiffness loss at the higher deflection levels was attributed primarily to glass fiber breaks.
Resin Flow During Autoclave Cure of Graphite-Epoxy Composites
Authors: Loos AC , Freeman WT
Published: December 2008

Resin flow during autoclave cure of graphite-epoxy composites was measured experimentally as a function of time. The data indicate that the ply-stacking sequence of the composite does not significantly influence the total resin mass loss. Resin flow data obtained from composites with different ply thicknesses and dimensions were compared with the results of the model of Loos and Springer. Good agreement was found between the data and the model.
Maturity Functions for Concrete Cured During Winter Conditions
Authors: Naik TR
Published: December 2008

The objective of this paper is to check the validity of the Nurse-Saul and the Arrhenius maturity functions for concrete cured under winter conditions.

The test specimens used for concrete compressive strength determination were 101.6 by 203.2-mm (4 by 8-in.) cylinders. (The measurements were made in English units.) These specimens were cured at nominal temperatures of 2.8, 12.8, and 22.8°C (37, 55, and 73°F). The cylinders were cast from concrete with water-to-cement ratios of 0.50, 0.60, and 0.70. Tests for compressive strength were performed at the ages of 12, 18, 24, 36, 48, 72, 120 (five days), and 168 h (seven days). The maturity and temperature of the cylinders were recorded at each test age. Curves were plotted for the compressive strength versus the relative maturity at 20°C for each water-to-cement ratio and for different curing temperatures. It was determined that the Arrhenius function gives better correlation between the relative maturity and the strength than the Nurse-Saul function. The author concludes that the Nurse-Saul function should not be used for maturity-strength determination under winter curing conditions.
Three-Dimensional Elastic-Plastic Finite Element Analysis of Three-Point Bend Specimens
Authors: Wellman GW , Rolfe ST , Dodds RH
Published: December 2008

Elastic-plastic finite element analyses of the three-point bend specimen geometry were performed as part of an investigation to study the application of the crack tip opening displacement (CTOD) fracture parameter to flawed pressure vessels. The elastic-plastic fracture mechanics (EPFM) parameters, CTOD and J, were determined from the results of two- and three-dimensional finite element analyses. Three sizes of the preferred specimen geometry (thickness, t, by depth, 2t, by span, 8t) and five steels with varying stress-strain characteristics were considered. To obtain experimental results for comparison, tests were conducted in accordance with the procedure outlined in British Standard BS 5762:1979, “Methods for Crack Opening Displacement Testing.”

Analytical CTOD values were determined from the finite element nodal displacements using the 90-deg intercept procedure proposed by Rice. Semi-empirical CTOD values were computed by applying the formula in BS 5762:1979 to the computed clip-gage displacements. The finite element analyses were demonstrated to yield CTOD values consistent with the experimental values for the three-point bend specimen. This represents the first step in verifying use of the finite element method to predict applied CTOD values in more complex structures.

The J-integral was determined from two-dimensional finite element results using direct contour integration. The J-integral values were used in conjunction with the corresponding CTOD values to develop an improved correlation between J and CTOD for a wide range of material characteristics.

The paper concludes with a discussion of “level of performance” for the three-point bend specimen. The level of performance is characterized by the value of CTOD at various sizes of the plastic zone as a function of specimen size and material. Three levels of performance are identified: (1) KIc as defined by ASTM Test for Plane-Strain Fracture Toughness of Metallic Materials (E 399), (2) development of a plastic hinge, and (3) initiation of ductile fibrous tearing. An understanding of these levels of performance and their relation to values of CTOD is essential in developing realistic requirements for material toughness.
Observations on a Fracture Mechanics Approach to Fatigue Crack Initiation in Ti-6Al-4V
Authors: Yoder GR , Cooley LA , Crooker TW
Published: December 2008

Resistance to the initiation of fatigue cracks in Ti-6Al-4V has been determined from blunt-notched (keyhole) and sharp-notched (V) compact specimens of the WOL type. The primary alloy studied was in the mill-annealed condition with an ultimate tensile strength of 1034 MPa (150 ksi). In the case of the blunt-notched specimen, the notch root radius was ρ = 1.59 mm (0.0625 in.); for the sharp-notched specimen, ρ = 0.25 mm (0.010 in.). The influence of surface roughness, 0.4 μm versus 1.8 μm (16 μin. versus 72 μin.), on fatigue crack initiation resistance has also been examined. Notch root surfaces were specially prepared to remove all machining marks in the thickness direction. Specimens were cycled under constant load amplitude conditions in air with a stress ratio of R = 0.10. Cycles-to-initiation data normalize very well for the two specimen types when analyzed in terms of the ratio of stress intensity factor range to the square root of the notch root radius, ΔK√ρ. The fatigue crack initiation resistance also appears to be independent of surface roughness in the notch root region. Moreover, fatigue crack initiation resistance from these notched compact-type specimens is found to correlate well with fatigue strength determined from smooth, rotating beam specimens of this very same material. Finally, fatigue crack initiation resistance has been measured with the blunt notch compact specimen for a number of beta-annealed Ti-6Al-4V alloys with a broad range of oxygen contents (0.06 to 0.20 wt%). Though oxygen content can have a pronounced influence on fracture toughness, the present data do not indicate a significant influence of oxygen content on fatigue crack initiation resistance.
Strain-Rate Effects on the Ductile/Brittle Transition in Steels
Authors: Knorovsky GA
Published: December 2008

A recently implemented fracture control plan for structural steel high-way bridges makes use of a linear relation to describe the effect of strain rate on the ductile/brittle transition temperature as a function of yield strength. Literature data show that the predictions of the aforementioned relation are not general. An alternative analysis is offered along with a qualitative model for understanding the phenomenon. Results of an experimental program investigating microstructural effects on the ductile/brittle strain rate dependence are also presented. The results exhibit linear behavior of ΔTdb versus Δσ/σ, where ΔTdb is the transition temperature shift, σ is the yield stress, and Δσ is the change in yield stress caused by strain rate. The magnitude of the temperature shift, however, is dependent upon the test specimen used. Factors discussed include microstructure, type of test specimen (Charpy V-notch, nil ductility temperature [NDT], modified NDT, or compact toughness), crack initiation versus crack propagation, and implications for regulatory bodies.
Application of Slow-Strain-Rate Tests to Defining the Stress for Stress Corrosion Crack Initiation in 70/30 Brass
Authors: Yu J , Henry Holroyd NJ , Parkins RN
Published: December 2008

Tapered and plain cylindrical, as well as flat rectangular, specimens have been used for determining the stress to initiate cracking in 70/30 brass immersed in 1M NaNO2 (sodium nitrite solution) whilst subjected to slow strain rate tests. A single tapered specimen can give threshold stresses reasonably close to those obtained by the use of a number of plain specimens loaded at a given strain rate to various stress levels. Monitoring of the current output of a potentiostat used for controlling the specimen potential also can give a reasonable indication of the stress at which cracking initiates. The stress for initiation was varied by varying the grain size of the brass, which also promoted changes in those parameters most frequently measured in the context of slow-strain-rate tests, such as percent reduction of area or nominal ultimate tensile strength, that are more influenced by crack propagation than initiation, but the effects of grain size upon crack propagation were less marked than the effects of change in strain rate. Thus grain size variations have a much greater influence on aspects of crack initiation than propagation, although in relation to the latter the fracture path was markedly dependent upon grain size as well as strain rate.
An Evaluation of Environment-Enhanced Fatigue Crack Growth Rate Testing as an Accelerated Static Load Corrosion Test
Authors: Shih TT , Clark WG
Published: December 2008

Room-temperature hydrogen sulfide gas (446 kPa [50 psig]) fatigue crack growth rate data were developed for an AISI 4340 steel heat treated to strength levels ranging from 634 to 1289 MPa (92 to 187 ksi). These data were compared with KIscc corrosion threshold data for the same steels in an attempt to establish a correlation between relatively short-time, corrosion-fatigue crack growth rate test results and long-time static-load KIscc data. Results show that corrosion-fatigue crack growth data can be used to rank the overall crack body corrosion susceptibility of AISI 4340 steel. However, a quantitative correlation does not exist with long-time KIscc threshold behavior. Recommendations for further work required to characterize the interaction between corrosion-fatigue crack growth and KIscc threshold behavior are discussed.
Extractive Metallurgy of Zirconium—1945 to the Present
Authors: Stephens WW
Published: December 2008

Although the history of the reduction of zirconium dates from 1824 and the first ductile zirconium metal was produced in the laboratory in 1914, modern reduction practice was pioneered by the U.S. Bureau of Mines starting in 1945.

This paper reviews the history of the extractive metallurgy of zirconium from the early work of W. J. Kroll and co-workers at the Bureau of Mines in Albany. Ore., through the commercial development of the production of reactor-grade zirconium metal which was spurred by the requirements of the Naval Reactor Program and the development of commercial nuclear power.

Technical subjects covered include processes for opening the ore, zirconium-hafnium separation, chlorination of zirconium oxide, reduction processes, and electro-winning of zirconium metal. Proposed new processes and process modifications are reviewed.
Irradiation Creep and Growth During Proton and Neutron Bombardment of Zircaloy-2 Plate
Authors: Chapman OJV , McElroy RJ , Sheldon BE
Published: December 2008

Proton irradiation creep and in-pile creep and growth tests have been conducted on specimens cut from the same rolled and annealed Zircaloy-2 plate. The proton irradiation creep tests were carried out over the following ranges: stress, 0 to 267 MPa; damage rate, 0.15 to 7.0 × 10−7 dpa/s; temperature, 513 to 613 K; and dose, up to 1.44 dpa.

These data were analyzed in detail on the basis of single variable tests to give a phenomenological equation of the form ˙ϵϒ=˙G+Aσnφmexp(−¯QRTq) where ˙ϵT = total strain rate, ˙G = growth rate, σ = applied stress, φ = damage rate, = growth rate, σ = applied stress, φ = damage rate, T = temperature, and A, n, m, Q, R, and q = material parameters.

Over the range studied the stress and damage rate exponents were unity and the temperature dependence was best described with a q-value of 0.5. Longitudinal and transverse specimens exhibited a degree of creep anisotropy.

Additional specimens were reactor preirradiated to a dose of 1.0 dpa and tested in the ion accelerator. The results of these tests were in excellent agreement with the equation.

The in-pile tests were carried out at the following values: stress, 80 and 140 MPa; damage rate, 9.7 × 10−8 dpa/s; temperature, 543 to 593 K; and dose, up to 1.42 dpa. These tests also gave results that were in good agreement with the prediction of the equation.
High-Fluence Irradiation Growth of Zirconium Alloys at 644 to 725 K
Authors: Tucker RP , Fidleris V , Adamson RB
Published: December 2008

Irradiation growth behavior of zirconium, Zircaloy-2 and Zircaloy-4,Zr-2.5Nb, and Zr-3.5Sn-0.8Mo-0.8Nb (EXCEL) was studied on specimens irradiated in the Experimental Breeder Reactor II (EBR-II) to fluences of 1.2 to 16.9 × 1025 neutrons (n)·m−2 (E > 1 MeV) in the temperature range 644 to 725 K. In Zircaloy, growth and growth rate were observed to increase continuously with fluence up to 16.9 × 1025 n·m−2 with no indication of saturation in either recrystallized or cold-worked materials. Positive growth strains of 1.5% and negative strains of approximately 2% to 2.5% were observed in both recrystallized and cold-worked Zircaloy. The formation of both a-type loops and c component dislocations is recrystallized Zircaloy under irradiation appears to be the basis in this material for growth strains similar in magnitude to those in cold-worked Zircaloy. Alloy additions to zirconium can increase growth by as much as an order of magnitude for a given texture at the higher irradiation temperatures and fluences. A sharp change to increasing growth rate with temperature occurs in Zircaloy at ∼670 K, with a similar trend indicated for the other alloys. Although growth in all these alloys is a strong function of crystallographic texture, an exact (1–3f) type of dependence is not always apparent. In Zr-2.5Nb the dependence of growth on texture appears to be masked by the precipitation of betaniobium, with a transition to a well-defined texture dependence being a function of fluence and temperature. Significant differences in growth behavior were observed in nominally similar Zircaloys, apparently due to minor microstructural or chemical differences.
Effect of Lithium Hydroxide on the Corrosion Behavior of Zircaloy-4
Authors: McDonald SG , Sabol GP , Sheppard KD
Published: December 2008

Post-transition corrosion data were obtained on Zircaloy-4 tubing at temperatures of 589, 616, and 633 K, and in lithium hydroxide (LiOH) concentrations that ranged from 0.001 to 0.1 molal. Following the corrosion exposures, the oxide films of selected specimens were analyzed to determine the quantity of lithium that had been absorbed as a function of corrosion temperature and LiOH concentration. Analyses of the weight gain versus exposure time data yielded several conclusions. First, LiOH concentrations as low as 0.01 molal (70-ppm lithium) can lead to significantly increased corrosion rates, particularly at high temperatures (633 K). Second, at moderate concentrations, 0.01 to 0.06 molal (70 to 420 ppm lithium), there is an intermediate post-transition region where the corrosion rate is only slightly greater than that typical of pure water exposures. Ultimately, however, there is a transition to a more accelerated corrosion rate. Third, there is a synergistic effect between corrosion temperature and LiOH concentration in that the cooperative effect of these two parameters on post-transition corrosion rate is greater than their independent sum. These synergistic effects can be described by an empirical Arrhenius-type equation where both the frequency factor and activation energy are functions of the LiOH concentration. Data obtained from the lithium analyses performed on the various oxides suggest that accelerated corrosion begins when the lithium concentration in the oxide reaches a critical value.
Out-of-Pile Nickel Alloy-Induced Accelerated Hydriding of Zircaloy Fasteners
Authors: Clayton JC
Published: December 2008

Mechanical joints between Zircaloy and nickel-bearing alloys, mainly the Zircaloy-4/Inconel-600 combination, were exposed to water at 232 and 271°C to study hydriding of Zircaloy in contact with a dissimilar metal. Accelerated hydriding of the Zircaloy occurred at both temperatures. At 232°C the dissolved hydrogen level of the water was over ten times that at 271°C. At 271°C the initially high hydrogen ingress rate decreased rapidly as exposure time increased and was effectively shut off in about 25 days. Severely hydrided Zircaloy components successfully withstood thermal cycling and mechanical testing. Chromium plating of the nickel-bearing parts was found to be an effective and practical barrier in preventing nickel alloy smearing and accelerated hydriding of Zircaloy.
Effect of Bundle Size on Cladding Deformation in LOCA Simulation Tests
Authors: Chapman RH , Crowley JL , Longest AW
Published: December 2008

Two loss-of-coolant accident (LOCA) simulation tests were conducted to investigate the effects of temperature uniformity and radial restraint boundary conditions on Zircaloy cladding deformation with a very low flow of superheated steam. In one test (B-5), boundary conditions typical of a large array were imposed on an inner 4-by-4 square array by two concentric rings of interacting guard fuel pin simulators. In the other test (B-3), the boundary conditions were imposed on a 4-by-4 square array by a noninteracting heated shroud. Test parameters conductive to large deformation were selected to favor rod-to-rod interactions.

The tests showed that rod-to-rod interactions play an important role in the deformation process. While burst temperatures and burst strains were not affected appreciably, the interactions in the large array significantly influenced the deformation patterns and caused greater volumetric expansion of the interior simulators. Volumetric expansion of the simulators in the small array was significantly less than that for the central array of the large test; burst strains were approximately the same. Burst temperature-pressure data for the small array and for the outer ring of simulators in the large array agreed with predictions based on single-rod heated shroud tests. All the B-5 simulators burst at approximately the same temperature; however, the interior simulators burst generally at much lower pressures than the exterior ones, and their performance did not agree as well with the prediction.

It was concluded that, for conditions conductive to large deformation, at least two concentric rings of deforming guard simulators are necessary to model radial temperature and mechanical boundary effects of large arrays in LOCA simulation tests and that flow area restriction may be underestimated by small unconstrained bundle tests.