bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Optimum Crowning in a Line Contact Cylinder-to-Cylinder Rolling Contact Fatigue Test Rig
Authors: Sugiura I , Ito S , Tsushima N , Muro H
Published: March 2009

The cylinder-to-cylinder rolling contact fatigue rig is a line contact type of accelerated test rig. As an example of the test results from this rig, an investigation of the influence of the full crowning value on the rolling contact fatigue life is described. In the contact stress distribution along the axis of the line contact, the contact stress at the crowning edge, Pedge, has a 1.4 times larger influence on the rolling contact fatigue life than the maximum contact stress, Pmax, at the center of the contact area; the rolling fatigue life is therefore determined by Pmax or 1.4 Pedge, whichever is larger. This result can also be interpreted by the contact stress at the edge, Qmax, calculated by Moyer's method. Then the rolling fatigue life is determined by Pmax or Qmax, whichever is larger. The optimum crowning value is the value which gives Pmax = 1.4 Pedge or Pmax = Qmax.
A Four-Bearing Fatigue Life Test Rig
Authors: Hobbs RA
Published: March 2009

Specially developed machines for fatigue testing of rolling bearing steels frequently operate at stresses higher than the elastic limit, have contact conditions that differ widely from those in practice, or require special expensive test pieces. An alternative view is that standard bearings should be tested under conditions more closely simulating practice but at a stress level high enough to produce an acceptable test duration.

To this end, a rig containing four size 6208 bearings was developed and has been in use for many years. This paper describes the rig, which has recently been approved by the appropriate committee of the British Institute of Petroleum as a proposed test method for lubricating fluids and their effect on fatigue life. Normally, 32 bearings are tested to minimize the effects of scatter inherent in fatigue life testing, and since the rig is relatively in-expensive several may be run concurrently. When the sudden death technique is used, a test may be completed in less than 4 weeks.

The results from the rigs presented show the life improvement associated with vacuum-degassed steels manufactured by a basic electric arc process and the effects of oil film thickness on these lives. Other work exposes the severe life reduction caused by some fire-resistant fluids, and results from modified rigs at elevated temperatures are reported. The technique of sudden death testing is discussed, and results are presented which tend to confirm its validity.
Effect of Test Variables on the Rolling Contact Fatigue of AISI 9310 and VASCO X-2 Steels
Authors: Lamothe RM , Zagaeski TF , Cellitti R , Carter C
Published: March 2009

An investigation of two gear steels, AISI 9310 and VASCO X-2, carburized to a depth of 1.524 mm, was conducted to evaluate the effect of materials processing parameters on the fatigue lives of these materials in rolling contact fatigue, in single-tooth bending fatigue, and, finally, in a four-square dynamometer gear testing fixture. The study was carried on simultaneously at the International Harvester Co. (IH) and the Army Materials and Mechanics Research Center (AMMRC).

Rolling contact fatigue (RCF) was performed on two types of RCF machines which yielded different mean lives for each material. The RCF testing at IH was done on a machine designed to produce a 30 percent negative slippage at a contact stress magnitude of 3102 MPa (1 MPa = 145 psi). The AMMRC RCF tests, on the other hand, were conducted on a machine designed primarily for evaluating the fatigue life of ball bearings and had no provisions for including slippage. The magnitude of the contact stress obtained in the AMMRC tests was adjusted to 5171 MPa.

The mean fatigue life of VASCO X-2 in comparison to AISI 9310, was approximately five times greater at the B50 mean life on data generated with the IH machine. The higher fatigue life of VASCO X-2 was attributed to surface carbides and retained austenite. However, data generated on the AMMRC apparatus indicated the reverse, that is, the mean life of AISI 9310 steel was greater than that of VASCO X-2. Rationales for the observed differences in mean lives between the different materials and between the results of the two testing apparatuses are presented.
An Evaluation of Double-Torsion Testing—Experimental
Authors: Pletka BJ , Fuller ER , Koepke BG
Published: March 2009

Recently, the double-torsion (DT) technique has been widely used for fracture mechanics studies of brittle materials. The technique is popular for a number of reasons. First, the compliance analysis of a precracked DT specimen indicates the applied stress intensity factor, KI, is independent of crack length. This allows tests to be run conveniently on opaque samples and in hostile environments. In addition, specimen and loading geometries are simple and easily adapted to most testing machines. Furthermore, specimens generally are precracked easily and slow crack growth data can be obtained using simple load relaxation tests. As in most testing techniques, however, experimental conditions may arise under which the validity of the data may be in question. For instance, the independence of KI on crack length in a DT specimen occurs over only a limited range of crack lengths. The crack propagation characteristics have also been shown to be dependent on the specimen dimensions. Finally, irreproducibility of slow crack growth data occurs under certain testing conditions.

In this paper these and other experimental aspects of the DT test are examined in order to define the conditions under which the data are valid. Among the topics discussed are specimen and loading geometry, precracking techniques, data reproducibility, slow crack growth measurements, and comparisons of DT data with other techniques.
Fracture and Multiple Cracking of Cementitious Composites
Authors: Naaman AE , Shah SP
Published: March 2009

Cementitious composites consist essentially of a Portland cement paste, mortar or concrete matrix reinforced with steel (primarily) or mineral fibers. Compared to fiber reinforced polymeric and metallic matrices they form in a way a different class of composites. Their primary characteristics are: (1) that the ultimate tensile strain of the matrix is much lower than the yield or ultimate tensile strain of the fibers, and (2) the bond strength at the fiber matrix interface is relatively small (there is little adhesion in the chemical sense).

Attempts have been made to calculate some fracture properties of these composites, using linear elastic fracture mechanics approach, by testing notched beam specimens, notched tension specimens, or cleavage type specimens. The results have been only partly successful because these composites may not show a brittle type of failure depending upon the relative dimensions of the specimen and the length of the critical crack (in the Griffith's sense). Tests on double cantilever type cleavage specimens of Portland cement mortar reinforced with steel fibers showed that a pseudo-plastic zone develops in front of an advancing crack. In this zone the matrix is cracked but the fibers are in a state of pull-out. If the plastic zone is larger than the specimen cross section, then instead of a rapid crack propagation, multiple cracking and ductile failure may occur. The length of the pseudo-plastic zone can be determined from the results of the cleavage tests and depends on: (a) the length, aspect ratio, volume fraction, spatial distribution, and the pull-out behavior of the fibers, and (b) the properties of the matrix.

It is concluded that for cementitious composites for which no fracture testing standards exist, specific experimental techniques to measure fracture properties and analytical approaches to interpret their values, must be developed.
Application of Fracture Mechanics Concepts to Structural Ceramics
Authors: Wiederhorn SM , Ritter JE
Published: March 2009

Techniques of improving the reliability of ceramic materials in structural applications are described. Based on fracture mechanics concepts, these techniques use strength, or fracture mechanics methods of measurement to characterize the delayed failure behavior of ceramic materials. The techniques have been tested experimentally; for several materials, agreement between theory and experiment is satisfactory. For other materials agreement is not satisfactory, suggesting that additional experimentation is needed to evaluate the limits of the theory fully and to identify those materials for which the theory is applicable.
Localized Ductility Method for Evaluating Zircaloy-2 Cladding
Authors: Coffin LF
Published: March 2009

The localized ductility method has been shown to be a useful laboratory method for evaluating the mechanical performance of fuel cladding under conditions that approximate that of pellet-clad interaction (PCI). Using the method on unirradiated annealed and cold-worked cladding, performance is determined in flowing gaseous iodine and cesium plus cadmium liquid metal. In the case of iodine, increasing temperature and decreasing strain rate enhance the embrittlement, as does a texture in which the basal pole is in the direction of the applied stress. Further, microcracking is not found to occur below a finite plastic strain. The behavior is consistent with a film rupture mechanism for chemical-assisted cracking. For cesium plus cadmium, cracking is found in Zircaloy-2 above a threshold level of stress as indicated by the performance of constant crosshead and predefected constant load tests.
Stress Corrosion Crack Initiation and Growth and Formation of Pellet-Clad Interaction Defects
Authors: Videm K , Lunde L
Published: March 2009

The critical events leading to stress corrosion failure of fuel rods are poorly understood. The aim of the present work is to acquire data on stress corrosion cracking (SCC) initiation and crack growth and to use these data for improving our understanding of fuel rod failures.

Crack growth has been studied as a function of stress intensity by means of cladding specimens with fatigue precracks of different sizes. The SCC growth rate was found to increase with the ninth power of the stress intensity.

Smooth SCC specimens have been studied under constant load and under constant strain rate conditions. By applying the crack growth functions (determined by experiments with the fatigue precracked specimens), the times spent to propagate a crack and to initiate a crack as a function of stress have been deduced.

The effect of irradiation on the SCC properties has been investigated with specimens irradiated in Halden boiling water reactor (HBWR).
Out-of-Pile Testing of Iodine Stress Corrosion Cracking in Zircaloy Tubing in Relation to the Pellet-Cladding Interaction Phenomenon
Authors: Peehs M , Stehle H , Steinberg E
Published: March 2009

To investigate iodine stress corrosion cracking on the behavior of Zircaloy tubing, a standard test procedure with internally pressurized creep specimens (I-SCC standard test) and a split-ring test (I-SCC laboratory test) were developed. The threshold value for brittle cracking in iodine is 10-6 g iodine per square centimetre. The uniform elongation shows a clear minimum in its dependence on strain rate. Basal pole orientations in the range of ±50 to ±70 deg relative to the radial direction are the most I-SCC sensitive textures. The I-SCC process occurs in several stages; incubation, crack nucleation, and propagation. A thermodynamic evaluation indicates that I-SCC only occurs when zirconium iodides condense on the Zircaloy surface. Results show that comparisons of the I-SCC susceptibility of tubing manufactured in different manners should be made at the same point on the strain rate versus uniform elongation curves; for example, at the strain rate with the minimum of uniform elongation.
A Microstructure-Based Constitutive Relation for Dilute Alloys of α-Zirconium
Authors: Hartley CS , Lee J-J , Garde A , Chung HM , Kassner TF
Published: March 2009

The microstructural basis for a particular form of constitutive equation relating true stress to true plastic strain in Zircaloy is examined. It is shown that simple physical assumptions about the work-hardening mechanism can lead to an equation of the form τ=τi+Kγn(γ˙/γ˙0)m relating the true stress τ to true plastic strain γ at a constant true strain rate γ˙. The parameters τi, K, n and γ˙0 are dependent on material parameters such as the shear modulus and the Burgers vector of slip dislocations. The strain-rate sensitivity m is shown to be strain dependent in this model. Analysis of experimental data obtained on Zircaloy-4 at two strain rates over a temperature range from 473 to 1073 K demonstrates that the equation provides an excellent fit to experimental data. However, the temperature and strain-rate dependence of the material parameters are not in accordance with the theory. It is concluded that accuracy of fit to stress-strain data cannot be used as a criterion for the validity of a microstructural model and that more accurate microstructural models are required to permit predictions of the variations of phenomenological coefficients with test conditions.
Procedures and Recommendations for the Culture and Use of Daphnia in Bioassay Studies
Authors: Goulden CE , Comotto RM , Hendrickson JA , Hornig LL , Johnson KL
Published: March 2009

Despite the widespread use of Daphnia magna as a test organism in bioassay studies, little attention has been devoted to conditions necessary for culturing healthy animals in the laboratory or to the quality and quantity of foods required during chronic life-cycle bioassays. Growth, reproduction, and survival in daphnids are very dependent upon the quality and quantity of their food. Different algal species and artificial diets have been recommended as foods for Daphnia but the impact of these foods on the health and reproduction of test organisms has not been carefully analyzed. We used the appearance of individuals (including the presence of lipid reserves), growth, reproduction, and mortality as criteria for evaluating the suitability of three different food types and food concentrations for chronic life-cycle tests and for determining the maximal duration for chronic life-cycle tests that will consistently yield reliable results. The three foods used were (a) a 1:1 mixture of two algal species, Ankistrodesmus falcatus and Chlamydomonas reinhardtii; (b) Selenastrum capricornutum, a green alga often used in bioassay tests; and (c) trout chow (PR-11) and baker's yeast, an artificial food diet.

We recommend that a diet of green algae be used in the culture and feeding of animals in life-cycle tests and that a food concentration of 1.25 mg dry weight of algae per litre of test water be provided for individual cultures daily. If the animals are fed three times a week, then 2.5 mg of algae should be used. We further recommend that lifecycle tests be run for 21 rather than 28 days to minimize the chance of low survival rates in control vessels. Methods are also described for culturing both D. magna and its food for use in life-cycle tests.
Evaluation of a Bacterial Bioluminescence Bioassay as a Method for Predicting Acute Toxicity of Organic Chemicals to Fish
Authors: Curtis C , Lima A , Lozano SJ , Veith GD
Published: March 2009

The relationship between the toxicity of 68 organic chemicals to fish and luminescent bacteria was evaluated. Chemicals for which 96-h median lethal concentration (LC50) values had been measured for fathead minnows (Pimephales promelas) in flow-through tests at the U.S. Environmental Protection Agency (EPA) Environmental Research Laboratory-Duluth, Minn., were tested using the Microtox toxicity analyzer (Beckman Instruments, Inc.). The Microtox system measures the decrease in luminescence of the bacterium Photobacterium phosphoreum in response to a toxicant. The toxicity end point is the 5-min median effective concentration (EC50), which is the concentration that causes a 50 percent reduction in light output.

The correlation between fish and bacteria toxicity for a composite of industrial chemicals and pesticides had an R2 value of 0.65. However, the relationship of these two end points for a semihomologous series of industrial chemicals appeared to be firm, with R2 being 0.96 for common alcohols. The feasibility of using the bacterial bioassay as a screening test in a cost-effective testing scheme is discussed.
Forging and Processing of High-Temperature Alloys
Authors: DeRidder AJ , Koch R
Published: March 2009

Optimum properties of superalloys are derived from the interactions of the composition, thermomechanical deformation, and heat treatment. Nickel-base alloys contain a variety of elements in a large number of combinations to produce various desired effects. The general characteristics of any specific precipitation hardening heat-resisting alloy is determined by its composition. Microstructural variations in forging stock can further influence forging and heat treatment response. Specific alloy composition, as affected by heat treatment, is characterized by the time-temperature relationship to produce various phases and compounds. Chemical banding and carbide distribution, for example, contribute to directional property variations through differential response to heat treatment. Structural response relative to final property effects is also influenced by recrystallization brought about through use of selected thermomechanical processing parameters. Special controls are required under these circumstances to ensure satisfactory structural uniformity in forged components of complex configurations. These combined effects of composition, deformation, and heat treatment produce certain microstructures relating to the final desired properties.
Review of Superalloy Powder Metallurgy Processing for Aircraft Gas Turbine Applications
Authors: Bartos JL
Published: March 2009

Substantial increases in raw material and labor costs have provided the impetus for many diverse investigations aimed at reducing the manufacturing costs of aircraft gas turbine hardware. One of the most significant programs conducted at General Electric during the past decade involves application of powder metallurgy (P/M) processing technology to the fabrication of nickel-base superalloy rotating components. The evolution of P/M technology and its application to a high-strength superalloy, René 95, in a number of diverse aircraft engine components is described. Initial development concentrated on fabrication of P/M hardware by hot isostatic pressing (HIP) cylindrical powder preforms and forging in a conventional die system to an oversize shape. Subsequent refinement of this HIP plus forge process included HIP for shaped preforms followed by forging in an isothermal die system to a near net shape.

Emergence of a second P/M processing technology, designated as-HIP, in which the powder is simply HIP and heat treated, thus eliminating all secondary metalworking operations, is also reviewed. The technical advantages and constraints, along with the projected economic benefits of this new, highly promising P/M process, are analyzed and examples of its application to engine hardware presented. The future of P/M processing in the aircraft engine business, particularly as related to development of advanced superalloy materials, is also discussed.
A Stability Analysis of Circumferential Cracks for Reactor Piping Systems
Authors: Tada H , Paris PC , Gamble RM
Published: March 2009

The high ductility and toughness of the stainless steel reactor piping system have made it virtually certain not to experience unstable crack extension. The present study attempts to provide theoretical assurance that the piping system will not suffer unstable crack extension even if severe circumferential cracking should occur. The analysis is based on the tearing instability concept and the tearing modulus criterion. Simplifications are conservatively made to facilitate the complicated analysis. The results are presented parametrically in graphical forms for convenience of general use. An application to a specific example is also discussed.

The results indicate that the ratio, L/R, is of major importance in consideration of crack stability, where L is the length of the pipe between supports and R is the radius of the pipe. It is shown that unstable crack extension would not occur in stainless steel piping systems designed in accordance with the American Society of Mechanical Engineers' (ASME) code even if severe circumferential flaws were present, provided that the values of L/R are less than about 200. Since the values of L/R for boiling water reactor (BWR) stainless steel piping systems are generally much smaller, large margins against unstable fracture are assured for these systems. When L/R exceeds 200, a more detailed analysis would be necessary to demonstrate crack stability.
Quasi-Static Steady Crack Growth in Small-Scale Yielding
Authors: Dean RH , Hutchinson JW
Published: March 2009

A numerical analysis of quasi-static, steady-state crack growth under small-scale yielding conditions has been carried out for antiplane shear (Mode III) and plane strain, Mode I. In addition to results for an elastic-perfectly plastic solid, the study includes results relating to the influence of strain hardening on stable crack growth. Limited results based on a corner theory of plasticity give some indication of the extent to which stable crack growth predictions are sensitive to the type of plasticity theory used.
Beta-Quenching of Zircaloy Cladding Tubes in Intermediate or Final Size—Methods to Improve Corrosion and Mechanical Properties
Authors: Andersson Th , Vesterlund G
Published: March 2009

Three batches of Zircaloy-2 tubing were beta-quenched prior to the final cold-rolling, cold rolled 80 percent, and annealed at 475 to 575°C. A fourth batch was β-quenched in the final size. For comparison, standard tubing was included in all tests performed. The second-phase particles were studied by means of optical and scanning electron microscopy. Corrosion testing was carried out at 400°C and in high-temperature (475 to 500°C) high-pressure steam. The mechanical tests comprised tension, burst, and creep testing under internal pressure.

Beta-quenching instead of an intermediate or the final anneal results in significant structural changes. The most striking features are the formation of a Widmanstätten structure consisting of plates of α-phase and the reprecipitation of much finer second-phase particles in the plate boundaries. Cold-rolling of β-quenched hollows followed by a final anneal in the α-range will give an equiaxed structure, but the size and distribution of the second phase obtained in β-quenching will not be markedly changed.

The weight gain at 400°C increases slightly as a result of β-quenching in intermediate or final size. In high-pressure steam at 475 to 500°C, on the other hand, such β-quenching has a dramatic beneficial effect on the corrosion resistance. At 500°C, for instance, specimens from tubing β-quenched in intermediate size show weight gain values of 55 to 95 mg/dm2, whereas specimens from standard tubing take values in the range 360 to 4280 mg/dm2. The explanation of this improvement seems to be the existence of small second-phase particles formed in α-plate boundaries as a result of dissolution and reprecipitation during β heat treatment and quenching. Experiences from boiling water reactor (BWR) channel corrosion of β-quenched Zircaloy-4 indicate that the 475 to 500°C high-pressure steam test forecasts very well the in-reactor resistance of Zircaloys to nodular corrosion under BWR conditions.

The short-term strength as measured in tension and burst testing is improved by β-quenching of hollows or finished tubes, whereas such treatment results in a slight drop in ductility, especially for tubing β-quenched in the final size. The 400°C transverse creep strength is increased by the introduction of β-quenching prior to the final cold-rolling. The improvement is caused mainly by small second-phase particles, formed during β-quenching, which give rise to precipitation hardening.
The Role of Film Rupture During Slow Strain-Rate Stress Corrosion Cracking Testing
Authors: Diegle RB , Boyd WK
Published: March 2009

The unique nature of the slow strain-rate technique for stress corrosion testing is discussed in terms of its ability to maintain repetitive rupture of corrosion films. It is first shown that the surfaces of alloys of engineering importance tend to be covered with films under electrochemical conditions that promote stress corrosion cracking (SCC). The relevance of this observation to conditions prevailing directly at the stress corrosion crack tip is considered next, and it is shown that a film-covered tip is a likely probability in several alloy-corrodent systems. It is proposed that film rupture can be considered a prerequisite for the operation of the two major proposed SCC mechanisms, namely, anodic dissolution and hydrogen embrittlement. The predominance of intergranular or transgranular cracking is ascribed to the morphology of slip within the alloys and possibly to the effect of solute segregation on corrosion kinetics. It is concluded that the success of the slow strain-rate technique as a severe test of SCC susceptibility results from its ability to expose the crack tip region to the aggressive environment through film rupture.
Application of Slow Strain-Rate Technique to Stress Corrosion Cracking of Pipeline Steel
Authors: Payer JH , Berry WE , Parkins RN
Published: March 2009

Slow strain-rate technique has been used extensively in the study of stress corrosion cracking (SCC) of pipeline steel. Results were obtained to guide development and evaluation of SCC control methods and to study the SCC process. Application of the slow strain-rate technique led to determination of the specific environment of practical importance, identification of effective SCC inhibitors, determination of critical potential range for SCC, increased awareness of the major role of strain rate in the SCC process, and development of coatings incorporating SCC inhibitors.
Effect of Oxyanions and Chloride Ion on the Stress Corrosion Cracking Susceptibility of Admiralty Brass in Nonammoniacal Aqueous Solutions
Authors: Kawashima A , Agrawal AK , Staehle RW
Published: March 2009

The stress corrosion cracking (SCC) susceptibility of admiralty brass in several nonammoniacal solutions of pH ∼8 has been investigated at 25 °C using the slow strain-rate technique. The SCC tests were made at a controlled potential of 300 mVH. This potential is close to the cupric oxide/cuprous oxide (CuO/Cu2O) equilibria, in near neutral solutions (6 < pH < 8), on the potential-pH diagram of copper. In the present study, cracking occurred in several solutions; the severity of the cracking depended upon the type of anion present in the test solution. The order of anions in decreasing tendency to promote SCC in admiralty brass was: NO2- > NO3- > ClO3- > SO4= > MoO4= > Cl- > WO4= > HCO3- > B4O7= > CrO4=. The estimated crack velocity ranged from high values of the order of 10-7 m/s in the nitrite solution to no cracking in the phosphate and the solutions following it in the above series. The cracking was always transgranular with considerable branching in some cases.
Stress Corrosion Cracking Susceptibility Index, ISCC, of Austenitic Stainless Steels in Constant Strain-Rate Test
Authors: Abe S , Kojima M , Hosoi Y
Published: March 2009

A new stress corrosion cracking (SCC) susceptibility index, ISCC, is proposed in constant strain rate SCC test both for transgranular (TG)SCC and for inter-granular (IG)SCC. ISCC is best defined by the equation Isec=Asec/Amech are the area of SCC fractured surface and that of mechanically fractured surface, respectively. It is found that there is a good correlation between ISCC in constant strain-rate test and the time to fracture in constant load test.
Comparative Findings Using the Slow Strain-Rate, Constant Flow Stress, and U-Bend Stress Corrosion Cracking Techniques
Authors: Daniels WJ
Published: March 2009

The testing of materials for stress corrosion cracking (SCC) in a use environment involves the risk that cracking may not be found by the test technique. When this happens, immunity to SCC may be incorrectly concluded. To avoid this type of error, the use of multiple testing techniques is recommended.

This report discusses the different findings for Type 304 stainless steel obtained by three SCC testing techniques: the slow strain-rate technique (SSRT), the constant flow stress (CFS) test, and the U-bend test. The comparative studies in 36.5 percent magnesium chloride solution show that the cracking mode has an electrochemical potential dependency. In sodium chloride solutions, in the range of 1 to 20 percent concentration, the studies show that the cracking has a critical strain-rate dependency.
Toughness of Ferritic Stainless Steels
Authors: Wright RN
Published: March 2009

A comprehensive review of the factors fundamental to ferritic stainless steel toughness has been undertaken. Emphasis has been placed on the micromechanisms of fracture and their effects on the ductile-to-brittle transition consistent with the Cottrell crack nucleation model. The general effects of strain rate, plastic constraint (including gage effect), and grain size are set forth. The basic fracture behavior of body-centered-cubic metals, iron and iron-chromium solid solutions, is summarized. Primary emphasis is placed on the role of second phases in the ferritic stainless steel fracture process, and carbides, nitrides, martensite, α'-precipitation, and σ- and χ-phases are discussed extensively. The role of titanium and columbium as gettering agents for carbon and nitrogen is considered. The effects of cold-work are set forth and a brief outline is made of annealing guidelines for optimized toughness. Finally, the fracture behavior of welds and weld heat-affected zones is discussed and approaches to improved as-welded toughness are reviewed.
Micromechanisms of Brittle Fracture in Titanium-Stabilized and α'-Embrittled Ferritic Stainless Steels
Authors: Grubb JF , Wright RN , Farrar P
Published: March 2009

Fe-26Cr alloys, with and without titanium stabilization, have been studied in an effort to clarify the micromechanisms of brittle fracture in the presence of titanium stabilization and α'-precipitation (475°C embrittlement). Tension testing, Charpy testing and metallographic evaluations have been undertaken. Microscopic observations of electropolished strips pulled in the ductile-to-brittle transition temperature (DBTT) range have been made. Titanium stabilization can lead to DBTT increases in low carbon and nitrogen alloys and this embrittlement is associated with intergranular microcrack formation. Embrittlement due to α' -precipitation seems related to flow stress increase and the α'-precipitation is seen to bring about a gross change in slip character, leading to the development of relatively few, but extremely intense slipbands.
On the Embrittlement and Toughness of High-Purity Fe-30Cr-2Mo Alloy
Authors: Saito S , Tokuno H , Shimura M , Tanaka E , Kataura Y , Ototani T
Published: March 2009

Experiments were conducted to explain unexpected embrittlement phenomena encountered in fabricating a high-purity Fe-30Cr-2Mo alloy. By means of a hydrostatic tension test with a Bridgman-type specimen it was found that the fracture behavior of the alloy is highly dependent on stress state. Under conditions of low triaxial stress, the alloy displays excellent ductility. Under conditions of high triaxial stress, however, it shows less strain to fracture and a transition from ductile to cleavage fracture. The toughness of the Fe-30Cr-2Mo alloy can be significantly improved by thermomechanical processing.
Some Factors Affecting Drainage of Moisture from Wet Insulation in Flat Roofs
Authors: Hedlin CP
Published: March 2009

Moisture often finds its way into flat roofs where it causes a reduction in the thermal resistance of the insulations and sometimes leads to the destruction of the roofing system. Various methods for removing moisture have been studied, but effective drying is usually difficult to achieve because the natural forces acting to remove moisture are small.

Some moisture may be drained from wet roofs, but because the slope is small or nonexistent and absorptive forces tend to retain moisture it is not usually an effective method. If the retentive forces can be overcome, however, drainage rates can be substantially increased.

In one outdoor study carried out on an experimental roof deck with 2 percent slope glass fiber, perlite-fiber, and wood fiber insulations were found to drain very slowly. Of the moisture contained in the insulation at the outset less than 25 percent drained out in the first 4 months of test.

In a second, laboratory study tests were carried out on a deck 2.4 m long with slopes of 2, 4, and 8 percent using a variety of underlays beneath wet glass fiber insulation. Drainage was slow when a plastic sheet underlay was used, but rates were higher with soil and vermiculite-asphalt underlays. The fourth underlay, polyester fabric, produced drainage rates that varied with deck, slope, and length of flap allowed to hang down at the end of the deck. This flap provides a suction force that increases the rate of moisture flow. As an example, moisture content was reduced from over 70 percent to less than 5 percent by volume in a period of 4 days with a slope of 2 percent and a 75 mm flap.
Moisture Transport in a Metal Building Roof Insulation System
Authors: Musgrave DS
Published: March 2009

Metal buildings generally are constructed with no ventilation between the metal roof sheet and the roof insulation. This situation may result in moisture accumulation in the insulation, if the insulation does not have a satisfactory vapor barrier. The insulation vapor barrier performance is not only a function of the vapor barrier material, but also a function of the vapor barrier seams and any components which must penetrate the vapor barrier. An experimental investigation of a metal building roof insulation system was conducted. The system consisted of faced insulation boards suspended below the purlins with light density insulation installed between the board and the roof sheet. A large scale moisture test facility was used. A 2.44 by 3.67 m (8 by 12 ft) roof test specimen was constructed using actual metal building construction procedures and materials. The interior side of the test specimen was maintained at 21.1°C (70°F) and 50 percent relative humidity, while the temperature above the roof sheet was held below -23.3°C (-10°F). In order to determine the temperature and humidity conditions within the roof plenum, the test specimen was instrumented with thermocouples and humidity gages. The test duration was 3 weeks, after which the test specimen was disassembled for visual observations of the interior portion of the roof section and to obtain specimen weights of the insulation. No significant moisture accumulated in the insulation or the roof cavity.
An Experimental Approach to the Study of Moisture Dynamics in Walls
Authors: Stewart MB
Published: March 2009

This paper reports on the design of an experimental facility to examine moisture levels in the various components of a building envelope over the course of seasonal weather patterns. Using analytical methods, the pertinent factors in moisture accumulation were identified and the wall panels were built using a range of these factors. In addition to the permeance of the building materials, the effect of solar heating and interior vapor pressure also were studied. In this way, the relative importance of these variables can be compared while at the same time allowing the other factors of actual weather conditions, such as wind and precipitation, to be included as random variables. By using this approach, a realistic appraisal of the relationship between these factors and moisture accumulation can be made. To illustrate the capabilities of this facility, some preliminary data collected the first year are shown and compared to model predictions using the recorded weather conditions. Limitations of the experimental program as well as future research needs are discussed.
Humidity Measurement and Modeling in a Residential Attic
Authors: Ford JK
Published: March 2009

Dry and wet bulb temperatures of the outdoor air and the air at three locations within an occupied residence in Pennington, N.J. have been measured. The water vapor pressures of the attic air are very variable and cannot be correlated with either outside or living space water vapor pressures. Extremely good correlation, however, is obtained between the dew point temperature of the attic air and the temperature of the underside of the roof. Evidence of condensation and mold growth was found on the exposed roof sheathing. A computer program is used to assess the potential for condensation on the roof sheathing under specified ambient conditions. The implications for the standards writer also are discussed.
Moisture Migration in Fibrous Insulating Materials Under the Influence of a Thermal Gradient and Its Effect on Thermal Resistance
Authors: Langlais C , Hyrien M , Klarsfeld S
Published: March 2009

The thermal conductivity of a high density mineral fiberboard has been experimentally determined as a function of water content, at ambient temperature. The measurements, performed on three different apparatus over a moisture range of 0 to 150 percent by weight, show that the temperature gradient causes a redistribution of moisture which affects the thermal conductivity. The results are strongly dependent on the experimental conditions (for example, the orientation of the specimen). The variation of thermal conductivity with respect to dry state may reach 10 percent for a moisture content of about 30 percent by weight. In practice, the main cause of moisture presence in fibrous insulating materials is adsorption. The quantities adsorbed at 90 percent relative humidity are of 2 percent or less (in mass). For this small amount of water the variation of thermal conductivity with respect to dry state is negligible. All the results are discussed with the present problems of standardization in mind. Of particular interest are the problems concerning the “corrected” values of thermal resistances or thermal conductivities of insulants “in use” (design λ value).
Laboratory Studies of Infrared Thermography in Roofing Moisture Detection
Authors: Jenkins DR , Knab LI , Mathey RG
Published: March 2009

A laboratory evaluation of infrared thermography for detecting moisture in roofing specimens is presented. This study was based on laboratory controlled specimen preparation and testing conditions. For steady state heat flow, and in a few cases, transient heat flow, the effects of moisture on the surface temperature of the roofing specimens were determined by thermocouples and thermography. Surface temperatures determined by infrared thermography were shown to correlate well with the thermocouple temperatures. Two system performance parameters were assessed: threshold moisture content and the slope of the instrument response versus moisture content curve.
Residential Moisture Conditions—Facts and Experience
Authors: Johnson RJ
Published: March 2009

Moisture in new homes built in the late 1940's and early 1950's was a significant problem. Few moisture problems in new homes have been reported to us in the past 20 years or so. Home size, family size, life style, thermal protection, double and triple glazing, and vapor barriers all contribute to the turnabout.

Moisture conditions in homes were looked into in two studies. In one study, 17 homes in four states were probed in mid-March 1977, when it was expected the moisture content of wood framing members would be at their high or near high due to any moisture condensation in walls. All moisture content levels were found to be well within the acceptable and expected range of equilibrium moisture contents (EMC) for wood framing members (6 to 14 percent) and well below the decay level in wood (20 percent or greater). There was no evidence of past or present water damage in any of these homes.

In another study, data were collected for 16 homes in north-central Utah, southern Alabama, northern Ohio, and central Maryland. Measurements were made in each home for approximately 1 week in the summer and 1 week in the winter. All homes had well ventilated attics. Some had attic vapor barriers and others had none. Calculations showed the average absolute humidities in winter in attics for homes with a ceiling vapor barrier were some 19 percent higher than for attics without a ceiling vapor barrier.

Much more extensive measurements probably would show no consequential difference in relative humidity in well ventilated attics with homes having a ceiling vapor barrier or those without. In practice, the millions of house years of experience with well ventilated and insulated attics, having no ceiling vapor barrier and no condensation problems, indicates that extremes of temperature, ventilation and lifestyle rarely occur simultaneously and to an extent necessary to produce attic condensation sufficient to cause moisture damage.
CW Laser Damage in AR Coated Alkaline Earth Fluorides at 3.8 µm
Authors: Detrio JA , Petty RD
Published: March 2009

We have measured the damage threshold of AR coated SrF2 and oriented single crystals of CaF2 using a CW chemical laser operating at approximately 3.8 m. The samples were irradiated for three seconds up to a total power of 8.4 kW. The specimens all failed at a power density of 22 kW/cm2 over a 0.3 cm2 area. The failure mode was not catastrophic and is believed to consist of plastic deformation due to compressive loading in the center of the irradiated region on the exit surface. The surface absorption is the dominant contributor to the failures. A novel statistical approach to defining the damage threshold and assessing the confidence level of the data was used.
Stress Corrosion Cracking—The Slow Strain-Rate Technique
Authors: Ugiansky GM , Payer JH
Published: March 2009

Description

Those in the fields of corrosion engineering and metallurgy will find that this publication offers and introduction for those unfamiliar to the slow strain-rate technique (SSRT) for stress corrosion cracking (SCC) in metals and relevant information the application of the technique for specific alloys of chemical environments. For those familiar with the technique, a data base is provided so that the results of the slow strain-rate tests can be compared with results from other SCC tests, such as constant load tests and constant strain tests. It is organized to address from several vantage points the use of the slow strain-rate technique. A series of papers concerns the SCC process and the relationship of the SSRT to relevant phenomena. Interpretation of results is the primary topic of several papers. Other papers discuss the application of the SSRT to specific alloys or environments. In addition, several papers focus on equipment and procedures using tests.
Properties of Austenitic Stainless Steels and Their Weld Metals (Influence of Slight Chemistry Variations)
Authors: Brinkman CR
Published: March 2009

Description

There are seven papers in this publication. Four deal with the influence of such elements as nitrogen and niobium on primarily elevated temperature behavior of AISI stainless steel Types 304, 304L, 316, and 316H. The other three papers deal with the effects of intentionally added or controlled as well as residual element content on weldability and subsequent mechanical properties of weld metal. Will be of particular interest to the designers, metallurgists, and suppliers of these materials, who must concern themselves heat-to-heat variability and ways of improving properties.
Design of Buildings for Fire Safety
Authors: Smith EE , Harmathy TZ
Published: March 2009

Description

The Symposium on Design of Buildings for Fire Safety was held during the Annual Meeting of the American Society for Testing and Materials, Boston, Mass., 27 June 1978. ASTM Committee E05 on Fire Standards sponsored the symposium. E. E. Smith, The Ohio State University, and T. Z. Harmathy, National Research Council of Canada, served as symposium chairmen and editors of this publication.
Community Noise
Authors: Peppin RJ , Rodman CW
Published: March 2009

Description

Contains 24 papers covering measurement, prediction, abatement and quantification including criteria and response. Addresses present day community noise from aircraft to burglar alarms.
Wear Tests for Plastics: Selection and Use
Authors: Bayer RG
Published: March 2009

Description

The volume addresses the complex nature of plastic wear, from various mechanisms by which polymers can wear and factors that influence these modes, to the influence of contact and environmental conditions on wear. The papers presented clearly indicate that useful and effective wear tests exist and that they can be developed for a given application.
Engine Coolant Testing: State of the Art
Authors: Ailor WH
Published: March 2009

Description

Twenty-one papers review past studies and provide new insights and techniques on cooling systems, coolants and anti-freezes, cavitation, corrosion, properties, service, and research and testing.
Toughness of Ferritic Stainless Steels
Authors: Lula RA
Published: March 2009

Description

Specifically addresses the need for attention to the mechanical properties, and toughness in particular, of ferritic stainless steel commensurate with their importance for such areas as design fabrication and operation of processing equipment.
Quality Assurance in Pavement Construction
Authors: Allen GJ
Published: March 2009

Description

Specifically addresses quality assurance in pavement construction by providing insight from four important perspectives.
Lifetime Factors in Silicon
Authors: Westbrook RD
Published: March 2009

Description

A comprehensive review published for the purpose of furthering standards development relating to carrier lifetime measurement, interpretation, and control.
Thermal Insulation Performance
Authors: McElroy DL , Tye RP
Published: March 2009

Description

Updates you on a wide variety of important topics with discussions in such critical areas as Overall performance in applications, Implementation of standard codes and accreditation procedures, Research procedures, and Needs for the future.
Asphalt Pavement Construction: New Materials and Techniques
Authors: Scherocman JA
Published: March 2009

Description

A book on the advances for all involved in design, testing, and construction of asphalt concrete pavements. Coverage includes asphalt-rubber binders, sulfur-extended asphalt binders, foamed asphalt binders, incinerator refuse aggregates.
Stainless Steel Castings
Authors: Melilli AS
Published: March 2009

Description

This book is based on the first international symposium for the presentation and discussion of the latest technology for stainless steel castings; the opportunity of providing an interaction among those interested in verifying, applying and manufacturing cast stainless steel components. The main subjects discussed include manufacture, heat treatment, welding, properties, applications, experiences, failure analysis, and alloy development.
Geotechnical Properties, Behavior, and Performance of Calcareous Soils
Authors: Demars KR , Chaney RC
Published: March 2009

Description

The papers in this publication contain a wide variety of subject matter, from lab and field studies by researchers to design considerations by practitioners, all related to calcareous soils. The first two papers provide useful summaries and general descriptive information on carbonates from marine and arid environments, respectively.
Composite Materials: Testing and Design (6th Conference)
Authors: Daniel IM
Published: March 2009

Description

This publication presents the latest developments in composites testing and design, including applications to the aircraft, automotive, and other industries. 31 papers comprise the contents and address subjects including test methods for mechanical and damage characterization; new types of composites, such as SMC, short-fiber, and ribbon reinforced; fatigue behavior; ultrasonic backscattering; and time-dependent behavior.