bluuebunny/crossref_metadata_2025 huggingface dataset:
Laboratory Evaluation of Fire-Resistant Turbine Fluids
Authors: Snyder G. H. S. , Manley L. W. , Messina N. V.
Published: August 2009

The trend toward higher steam temperatures has increased the possibility of fires from oil leaks in turbine systems. This has stimulated investigation of fire-resistant fluids for this application. Various chemical-base fluids are currently being studied in the laboratory, and at least one type is undergoing field trial. There is a need for development of suitable test methods for evaluating these fluids. Also, the use of such fluids will involve new design and operational considerations. The ASTM may be able to contribute to the resolution of these matters.
Antiwear Requirements for Navy Turbine Oils
Authors: King H. F. , Belt J. R.
Published: August 2009

A part of the Navy's continuing program of improving its turbine-gear lubricating oils to meet new machinery requirements is the development of oils with improved performance under high gear tooth loads. Test of highly-loaded experimental gears first showed the potential service need for such oils. A development program has resulted in several oils which give improved performance in laboratory and full scale shop tests of gears. Recently some new fleet units have been found to require these improved oils. To provide them, a revision of the Navy turbine oil specification has been made, defining the antiwear properties and load-carrying ability of the new oils. It is expected that in the future even better oils will be needed.
Rusting in Turbine Oil Systems
Authors: Furby N. W. , Hanly F. J. , Vincent J. A.
Published: August 2009

Rust-inhibited petroleum lubricating oils, now widely used, prevent rusting in turbine oil systems except under certain adverse operating conditions. This paper reviews the mechanism of rusting occurring in the liquid and vapor regions of a turbine oil system. Current accelerated rusting tests are discussed as related to rusting in service. Often, the bench-scale rusting tests used do not predict accurately the protection afforded in service. This can be the result of failure to recognize the important rusting variables and poor choice of bench test. Factors relating to rust-promoting conditions are reviewed. The importance of removal of water from the oil and avoidance of contamination with salt are stressed. A method is presented for monitoring rusting in turbine oil systems. Examples are given of its successful use in the field. The method permits continual surveillance of the existent rust protection afforded by the oil.
Monomolecular Films of Rust-Preventive Additives
Authors: Ries Herman E. , Cook Hurley D. , Loane Clarence M.
Published: August 2009

The first layer of additive molecules in an adsorbed rust-preventive film is the only layer that can react chemically with a metal surface; succeeding layers would be held by weaker physical forces. Film balance studies of monomolecular films show that good film-forming properties and high collapse pressures are characteristic of many rust-preventive compounds. Electron micrographs reveal structural details of monolayers that may be similar to those of adsorbed films on metal surfaces. Adsorption of radiostearic acid from an oil solution onto iron and steel surfaces is initially rapid, but slows down as a monolayer is approached. Any apparent multilayer adsorption may be due to the increased adsorbing surface that results from oxide formation; the presence of water increases this effect.
Practices for Determining the Expected Life of Used Turbine Oils
Authors: Mastin R. G.
Published: August 2009

This paper presents data on used turbine oils obtained from a turbine oil testing service covering the past ten years. Oils from turbines of varying generating capacity and manufacture have been tested on a semiannual or annual basis. The service records of oils from nine turbines are used in this study. From these data, methods for determining the expected life of used turbine oils have been developed, and practices have been evolved which will greatly extend the life of these oils.
Introduction
Authors: Vanick J. S.
Published: August 2009

Commercial gray iron castings are often designed in complex shapes which may integrate a number of simple geometrical figures into a final form. Plotting the flow of stress in a complex casting under load may become a jigsaw puzzle. One of the most aggravating cases occurs when a surface that should develop a tensional stress actually registers a compressional stress. Stress patterns that are further complicated by the cross-movements of static loads, dynamic loads, and thermal loads, combine to confuse the designer. In early designs, it is common to plan, build, test, and load the job to destruction, then redesign or “beef up” the weakened zones, and finally proceed with casting production. Because cast iron will break with a non-ductile fracture under simple tensile stress, its application has occasionally been avoided in favor of more ductile material which will deform and thus sound a warning, or it will malfunction in a dynamic loading system and thereby give notice of impending failure. Non-ductile fractures are known to develop in ductile materials like steel, as in the case of the fatigue failure. Methods for exploring the stress distribution in castings have been provided by various means and specifically in the strain-resistance wire gage system. Where equipment for stress-strain analysis is available, it has invariably been found possible to significantly improve the physical configuration of a given casting so as to meet more efficiently the stresses involved and also to materially decrease the weight of the casting, with an advantageous effect on economy. Equally important is the application of stress-strain measurements for the purpose of increasing confidence of the designer in gray iron as an engineering material.
Residual Stresses in Cylinder Blocks
Authors: King R. J.
Published: August 2009

The presence of residual stresses in castings has been recognized for sometime, possibly because these stresses manifest themselves externally by causing distortion and occasionally cracking. The mechanism by which residual stresses in castings are caused, that of differential cooling, is understood in its general aspects. However, little is known of the specific effects on residual stress of such things as chemistry of the iron, geometry of the part, and foundry technique or of the average residual stress level that might be expected in a certain casting. Seeking answers to some of these questions, an investigation was conducted at the Caterpillar Tractor Co. of the residual stresses in engine cylinder blocks. This paper discusses the experimental methods used in the investigation and presents some of the results.
An Analysis of Locked-In Stresses in Automotive Cylinder Blocks
Authors: Stockett S. J. , Lownie H. W.
Published: August 2009

The stress-relaxation method is often employed to determine the locked-in stresses in complicated structures. The usual procedure is to attach electrical strain gages to the structure at positions where stresses are to be determined and then to remove the sections containing the gages by sawing or drilling. Readings of the strain gages taken before and after the removal of the sections measure the amount of relaxation resulting when the constraint of other portions of the structure is removed. From a knowledge of the modulus of elasticity of the particular material, the magnitude of the locked-in stresses in the original structure can be calculated. The method is necessarily destructive to the structure. Care must be used in the cutting and sectioning operations so as not to introduce additional stress into the structure. Residual stresses were determined by this procedure on several automotive cylinder blocks by using three types of SR-4 electrical strain gages. Where space permitted and the orientation of the stresses was not known, rectangular strain rosettes of the AR-1 type were used. These gages consist of three independent elements, two of which are at right angles to each other, and the third of which is at an angle of 45 deg. to the other two. Where the orientation of the stresses could be predicted, single-element type A-1 gages were used. Single-element type A-7 gages were used where the area of particular interest was too small to use type A-1. The surfaces upon which the gages were attached were prepared with a small hand grinder followed by sanding through No. 000 emery paper. The blocks were then heated in an oven at 120 F. to drive off surface moisture, and the gages were attached with nitrocellulose cement while the castings were still slightly above room temperature. The cement was allowed to dry in air at room temperature for 2 hr. The blocks were then placed in an oven at 120 F. for 2 hr. and then raised to 160 F. for 5 hr. to harden the cement. While the blocks were still hot, the gages were coated with high-temperature ceresin wax to prevent absorption of moisture.
Strain Testing of Crankshafts, Engine Frames, and Cylinders
Authors: Hardy H. M. , Kuivinen T. O.
Published: August 2009

This paper presents some examples of wire-resistance strain gage testing of cast iron machine parts to determine design weaknesses. Design modifications were made on cast crankshafts, engine frames, and compressor cylinders before such parts were placed in production.
Strain Gage Tests on Diesel Cylinder Blocks, Heads, and Pistons
Authors: Newton C. L. , Swannack J. D.
Published: August 2009

This paper covers tests made with SR-4 gages on the cylinder block, piston, and cylinder head of a large diesel engine. The object was to determine the approximate magnitude of stress in these parts under operating conditions. The size of the parts and their availability precluded the possibility of making a laboratory set up. The tests were made with the partially assembled engine on the erection floor. The firing load was obtained by means of oil under pressure in the cylinder. A neoprene sealing ring was used as shown in Fig. 1. The wiring of each individual gage consumes time as well as increases the danger of thegage being damaged. A mercury contactor, shown in Fig. 2, was devised to permit a quick balancing of each gage. For gages on a horizontal surface, a 2-in. piece of No. 24 wire soldered to each lead will facilitate the use of the contactor.
Stress Analysis of a Cast Iron 125-lb. Valve Assembly
Authors: Malcolm V. T. , Low S.
Published: August 2009

During the war emergency, in view of the possibility that more strategic materials than cast iron might be conserved and procurement problems eased, some of the various standards associations, as well as consumers and suppliers, were advocating the use of cast-iron valves and fittings in place of steel. Unfortunately, there were few engineering data available and what were available-were too contradictory in nature, due to differences in test results caused by varying composition and cooling rates, to assure design and operating engineers that it was safe to rely on cast iron. Engineers had been trained for years not to use cast-iron valves, or fittings, in lines where a break might be costly in material or life or both. The A.S.M.E. code limitations on the use of cast-iron valves and fittings also hindered a wider use of the material. In order to determine accurately the feasibility of uprating various cast-iron valves, we started an experimental stress analysis program to determine the strength of cast-iron valves. As a 12-in. class 125 American Standard flanged-end valve represents a size and pressure class widely used in industry for all types of service, it was decided to carry out a series of tests on this type of valve. Figure 1 illustrates the valve and SR-4 strain gage locations. The investigative work was divided into 6 steps: 1. Location of governing stresses in the valve structure for various conditions simulating actual service. 2. Measurement of the hub flange stress (SH) in the valve flanges when made up with various types of gaskets. 3. Correlation of measured and calculated flange stresses. 4. Development of a method of calculating the hub stresses in a flanged joint made up with full face gaskets. 5. Comparison of the governing flange stresses in a valve and comparable pressure class fitting. 6. Fracture tests correlating tensile strength of the iron, as determined by 0.505-in. diameter tension test specimens cut from the casting, with the rupture stress of the casting.
Stress Analysis of Cast Iron for Valve Parts
Authors: Wyatt Harold
Published: August 2009

Use of SR-4 strain gages for determining stresses in cast iron requires a different approach than in the case of steel. Within the elastic limit of steel, an increase in strain is accompanied by a proportional increase in stress, since the modulus of elasticity of the steel is constant up to the yield point. The strain in steel can be measured by SR-4 gages. The stress then can be calculated from the modulus of elasticity. In the case of previously unstressed cast iron, at even low loads, the strain is a combination of plastic and elastic deformation. For this reason, the strain is not directly proportional to the stress. As shown in Fig. 1, the stress-strain curves for ferritic and austenitic cast irons are curves whose moduli change with change in stress. Therefore, strain measurements on cast iron obtained by the use of SR-4 strain gages cannot be used in the usual manner to calculate stresses. A technique using SR-4 strain gages for calculating stresses in cast-iron valve parts and in laboratory experiments has been developed. This technique has been proved accurate by both commercial and laboratory studies. It involves obtaining a stress-strain curve to fracture and a complete set of stress-strain curves for different load levels within a working range of loads. A modulus of elasticity can be assigned to a curve at each load level. These curves are then used to evaluate the strains determined with SR-4 strain gages.
Residual Stresses in Cast Iron Deaerating Trays
Authors: Cameron J. A.
Published: August 2009

This paper presents the results of an investigation conducted to determine the magnitude of residual stresses in sand-cast austenitic alloy cast iron deaerating feed-water heater trays. Tensile stresses very closely approaching the tensile strength of the material were found in certain areas of the castings. As a result, subsequent production parts have been given a stress-relief heat treatment intended to reduce residual stresses and eliminate field difficulties.
Stress Determination in Cast Irons for Railroad Service
Authors: Flinn R. A. , Ely R. J.
Published: August 2009

The determination of stresses in cast iron parts for railroad service has promoted both safety and performance. Serious errors may be encountered, however, if the stress-strain relationships of the particular cast iron structure being studied are not known, since strain measurement is the usual experimental method of finding the stress pattern. The first portion of the paper indicates that shape and amount of graphite may normally change the modulus of elasticity from 26 × 106 psi. to 10 × 106 psi. Total elongation varies from 5.5 to 0.18 per cent and tensile strength from 78,000 to 25,000 psi. Type of matrix may also affect the stress-strain curve since in some soft irons the shape of the graphite may cause permanent set at very low stresses. The second portion of the paper is devoted to measurement of strains during press fitting and to determination of residual stresses after different types of heat treatment. The apparent anomaly of tensile cracks in a quenched bore surface under residual compressive stress is explored. Finally, different cases of slow cooling, resulting in opposite residual stresses, are analyzed.
Location and Measurement of Stresses in Gray Iron Tractor Castings
Authors: Bornstein H.
Published: August 2009

For a number of years, we have been using the brittle lacquer technique and the resistance-type gages in studying stresses in gray-iron castings. The brittle lacquers are used to locate areas of high stress concentration and the direction of the stresses. Then, the wire gages are used to determine the amount of stress. Several examples may be of interest.
Stress-Strain Studies of Cast Iron for Textile Machinery Parts
Authors: Hillman Victor E.
Published: August 2009

The tests reported herein were undertakes by Crompton & Knowles Research Laboratories to obtain information on cast iron which had not previously been available. Before the advent of SR-4 strain gages, the determination of stress-strain relationships for cast iron was not practical for the average industrial laboratory. Any of the procedures which would give sufficiently accurate results were long and delicate and required costly equipment. When it is considered that elongation values for cast iron are less than 1 per cent in 2 in., it is not difficult to visualize the extreme accuracy required in measuring the strain produced by loads considerably below the ultimate strength. Moreover, most laboratories could not justify the time involved in making determinations, nor could they risk the damage to valuable extensometers if a specimen fractured prematurely during the process of testing. SR-4 strain gages made it possible to plot complete stress-strain diagrams for the various cast irons, such as those used in loom construction. In addition, the use of these gages resulted in obtaining more reliable values for the modulus of elasticity and the extent of its variation in irons of different composition. Such information was necessary to facilitate proper cross-sectional design and the development of maximum longevity in loom components.
1957 Supplement to the Metal Cleaning Bibliographical Abstracts
Authors: Harris Jay C.
Published: August 2009

The present supplement contains over 225 new references. The inclusion of early United States patents extends the coverage of this phase of the literature to make it as nearly complete as possible: Many of these references were contributed through the courtesy of A. B. McKee. This book supplements the previous editions (STP 90B, STP 90C) such that the years 1842 through 1956 are rather thoroughly covered. The references are arranged by year and secondarily by author, or by journal in which the article appeared if anonymous. The references are numbered consecutively. Additional references that fall within the dates previously covered have capital letters appended to numbers to indicate their correct position, while later references which must be inserted where capital letters are already assigned have been given lower case letters (for example, 72a) to indicate references prior to 72A. In order to facilitate reference to the abstracts, they have been thoroughly indexed by: Subject Author Specification Patent
A Rapid Technique of Consolidation Testing
Authors: Karol R. H.
Published: August 2009

Because of the heterogeneous nature of soils, engineering analyses of consolidation phenomena are always approximations—sometimes close, sometimes very rough. Consolidation tests performed in accordance with accepted laboratory techniques usually require a week or more to complete, a fact that appears inconsistent with the accuracy of the data obtained. This paper describes a small, compact machine capable of performing both consolidation and shear tests, and a testing technique which will materially reduce the time required for gathering consolidation and shear strength data, with little sacrifice of the accuracy obtained by longer test methods. The process involves three distinct steps: (1) design and construction of the Consolishear (2) pilot testing of the apparatus and correlation of test results with those of consolidometers using larger specimens, and (3) devising a procedure for testing by which the results of short-time tests could be accurately extrapolated to any desired time of testing. Preliminary tests performed in the conventional manner (on a stiff clay) indicated no significant difference in results obtained with the Consolishear and with larger consolidometers. Further testing (on the same soil) to develop a more rapid technique was carried out with the Consolishear. The proposed testing technique uses a time of application for each load increment of slightly more than the time required to reach 100 per cent consolidation (as established by conventional graphical construction). Extrapolation of test data is done by extending the lower portion of each compression-square root of time curve as a straight line to any desired time of loading (within limits). The resulting void ratio-pressure curve checks closely with that obtained by usual test methods. Complete shear and consolidation data can be gathered in a day, using a bank of three Consolishears.
The Effect of Temperature on the Consolidation Characteristics of Remolded Clay
Authors: Finn F. N.
Published: August 2009

When investigating the probable settlement of a structure it is customary to perform a series of consolidation tests on undisturbed samples of the compressible material underlying the foundation. The purpose of such a testing program is to provide the engineer with the necessary data for evaluating the probable compression and the time rate of compression of the actual soil strata. Normally, the consolidation tests will be performed in a laboratory where temperatures may vary from 60 to 80 F. However, specimens used for consolidation tests are frequently taken at a depth where temperatures sometimes vary from 40 to over 80 F. The question then arises as to what effect this difference in temperature, between laboratory test conditions and in situ condition, might have on the compressive characteristics of the material and whether or not the effect is of significant proportions. The consolidation characteristics of a soil are normally evaluated by application of the Terzaghi theory of primary consolidation, which is based on a number of, simplifying assumptions and approximations. To estimate the rate of compression from this theory, it is necessary to determine the coefficient of consolidation which is expressed by the formula: Cv=k(1+e)avγw.............(1) where: k = coefficient of permeability (assumed constant for each load increment), e = void ratio, usually the average for any load increment, av = coefficient of compressibility, and γ = unit weight of water From this relationship it can be seen that the coefficient of consolidation is directly proportional to the coefficient of permeability. It is known that permeability is related to viscosity which, in turn is related to temperature. Hence, it can be concluded that the coefficient of consolidation will depend on the temperature at which consolidation occurs. A closer analysis will show that the coefficient of consolidation should be directly proportional to temperature.
Introductory Summary
Authors: LaQue F. L.
Published: September 2009

A task group formed by Subcommittee IV of ASTM Committee A-10 on Iron-Chromium, Iron-Chromium-Nickel and Related Alloys and a similar group organized as Unit Committee T-5E of the National Association of Corrosion Engineers joined forces to undertake an exhaustive review of the over-all problem presented by instances of stress-corrosion cracking of austenitic stainless steels. The investigation embraced a review of case histories to define the circumstances under which such difficulties were being experienced, steps being taken to avoid or overcome the problem, research being undertaken to uncover facts about its nature as a basis for its cure, and an assessment of the theories that were being advanced to account for it. Details of these several phases of the investigation will be found in the sections of the full report of the task group devoted to these subjects. Presented here is an over-all summary of the results of the study.
Specimen Damage during Cutting and Grinding
Authors: Szirmae A. , Fisher R. M.
Published: August 2009

A detailed study has been made of the extent of deformation damage during mechanical and electrical spark cutting and planing of 3 1/4 per cent silicon iron during initial preparation of thin foil specimens. The results show the relation between rate of metal removal and depth of damaged layer, and demonstrate that under optimum conditions this layer can be as small as 5μ.
Electron Microscopy of Stress-Corrosion Cracking in AM 350 Steel for a Supersonic Transport
Authors: Tiner N. A.
Published: August 2009

Stress-corrosion behavior of AM 350 steel has been evaluated in natural atmosphere in dose proximity to the oceans. A number of stress corrosion-cracked specimens have been examined by means of electron microfractog-raphy. The salient microstructural features of crack initiation and propagation are described and interpreted.
Application of a Conducting Mask for Thinning Metallic Foils for Electron Transmission Microscopy
Authors: Despres Thomas A.
Published: August 2009

A technique is described by which thin film specimens can be prepared from a 0.002 to 0.006-in.-thick piece of metal very rapidly and with considerable improvement in handling facility. This technique has been successfully applied to aluminum, stainless steel, copper, Inconel X, nickel, and nickel-cobalt giving relatively large uniformly thinned areas. Application of a metallic mask and its effect on uniformity of electropolishing is discussed. Dependence of the degree of uniformity obtained in the thin foils during electropolishing upon (1) frontal area, and (2) thickness to frontal area ratio is suggested.
Investigation of Microstructure and Room-Temperature Fracture in SM-200 Nickel-Base Alloy
Authors: Hertzberg R. W. , Ford J. A.
Published: August 2009

The deformation and fracture behavior of SM-200, a nickel-base alloy, was studied at room temperature under tension and flexural loading. Electron fractographic techniques were extensively used to determine which phases and fracture mechanisms contributed to the fracture process. In addition, an investigation of the phase constitution of SM-200 using electrolytic phase extraction was conducted in order to relate mechanical behavior to alloy microstructure. A solution heat treatment was employed in an attempt to produce a microstructure exhibiting properties superior to those shown by as-cast material. Failure was found to occur along subgrain boundaries containing titanium carbide particles and massive γ′ clusters in as-cast materials, while TiC and M23C6 particles were considered responsible for subgrain boundary fracture in solution heat-treated specimens.
Microconstituents in High-Speed Steel
Authors: Koh P. K. , Nikkel H.
Published: August 2009

Electron microprobe analysis can be applied to the study of microconstituents in high-speed steel. In situ analyses were made in alloy carbides and manganese sulfide inclusions. Apparent heterogeneity is shown in the iron and vanadium contents of three neighboring M6C carbides, and the fact that VC carbides contain considerable amounts of alloying elements other than vanadium is illustrated. In a massive VC carbide no significant composition changes were observed in its center after tempering, and annealing heat treatments were conducted in vacuum.
Variable Bias Illumination Control for the Electron Microscope
Authors: McPartland J. O. , Daniel J. L.
Published: August 2009

Continuously variable control of illumination intensity in the electron microscope can be achieved by use of photoconductive cells for the grid bias resistance in a self-biased electron gun. The simple, highly stable device consists of several photo cells connected in series facing a control lamp, all positioned in a light-tight compartment. Changing the lamp brightness varies the grid resistance from 500,000 ohms to more than 30 megohms, controlling illuminating beam current over a wide range. Microscope stability is unaffected.
Introduction
Authors: Rosenfeld M. S.
Published: August 2009

In keeping with a well established precedent, ASTM Committee E-9 on Fatigue again sponsored a Symposium on Structural Fatigue in Aircraft at the Pacific Area National Meeting held in Seattle, Wash., Oct. 31–Nov. 5, 1965. Previous symposia have concentrated on the basic mechanism of fatigue, the effects of notches and other discontinuities on the fatigue behavior of materials, and, to a limited extent, the behavior of full-scale structural assemblies and components under simulated service loadings. Until relatively recently the theory of probability as applied to structural problems has been neglected by the design engineer. As a result, the “reliability engineer” has entered the void left by the structural engineer and is attempting to establish reliability standards for structures similar to those established for nickel and dime hardware items. Consequently, the structures engineer must establish his own realistic reliability standards, or unrealistic standards will be established for him.
A New Technique for Helicopter Rotor Blade Service Life Substantiation
Authors: Amer K. B. , Sullivan R. J. , Eakin J. D.
Published: August 2009

A technique is described whereby helicopter rotor blade service life can be substantiated by combining laboratory fatigue tests with cyclic loading applied during conventional ground endurance tests of rotor control and power-transmission systems. The method for applying cyclic loading involves the use of excitation panels, which consist of an array of stationary panels properly spaced and located close beneath the rotor to excite a natural flapwise bending mode. During the investigation, blade cyclic moments were excited that were ten per cent higher than the maximum cyclic bending moment measured in flight on the same rotor blade. The level of fatigue loading could be controlled by adjusting the vertical distance between the panels and rotor. The more rapid application of load (third-mode excitation at nine per revolution instead of the conventional one-per-revolution occurrence of peak inflight loads), coupled with sustained application of damage (100 per cent of the time for panels instead of approximately 16 per cent of the time for a normal flight spectrum), permits the excitation panels to impose damage approximately 56 times faster than experienced in flight. Tests are now being conducted to determine generalized design rules for application of excitation panels to rotors of any number of blades of any size.
Fatigue Failure of a Redundant Structure
Authors: Heller R. A. , Donat R. C.
Published: August 2009

Multiple-load-path redundant structures have been utilized in “fail-safe” design applications for a long time without a thorough investigation into the statistical nature of their failure. Experiments conducted at the Institute for the Study of Fatigue and Reliability, of Columbia University, on a model ten-member redundant structure subjected to constant-amplitude loads have been analyzed, and the statistical distribution of consecutive failures was determined. The experimental results are compared with various theoretical computations which were found to be conservative.
Evaluation of Fatigue Capabilities of High-Performance Military Aircraft
Authors: Bouchard E. D.
Published: August 2009

A joint program has been established by the Air Force, Navy, and McDonnell Aircraft Corp. to accumulate flight load maneuver data for fatigue evaluation purposes on F-4 series aircraft. Data obtained in this program will permit constant surveillance of the flight load history being experienced by each individual F-4 airplane. Data on over-all F-4 usage are presented and discussed. Parameters being evaluated and methods for reducing data to study these parameters are outlined. Statistical representation and interpretation of various parameters are discussed. The benefits that can be derived from a comprehensive flight load monitoring program are emphasized.
Development of a Scatter Factor Applicable to Aircraft Fatigue Life
Authors: Impellizzeri L. F.
Published: August 2009

Scatter in fatigue test results is one of the more important factors to be considered in predicting a safe service life for aircraft. A scatter factor is developed using statistical techniques to cover the variation in fatigue life among nominally identical specimens subjected to identical loading histories. A procedure is included to handle those cases where the life demonstrated in the laboratory is a least-of-two test result. The statistical analysis is supplemented by a review of numerous constant- and variable-amplitude test results which reveals that the log normal distribution is applicable and the standard deviation of log life is constant within a certain range of average cycles to failure. Fatigue test results of 120 composite aluminum structures are utilized to compute an unbiased sample standard deviation. A significant development of the derived statistical approach is the removal of the necessity to determine confidence intervals for the true mean and standard deviation. This is accomplished by the introduction of a new random variable from which these unknown population parameters vanish.
Fatigue Tests of Unmachined, Mechanically Machined, and Chemically Machined Panels of Aluminum and Titanium Alloys
Authors: Whaley R. E.
Published: August 2009

Constant-level, completely reversed bending fatigue tests were conducted on unmachined, mechanically machined, and chemically machined aluminum and titanium alloy sheet panels. All unmachined panels had lower fatigue strengths than machined panels because of stress concentration factor differences at the failure locations. No appreciable differences in fatigue strength occurred as a direct result of the type of machining, but the fatigue lives were inversely proportional to the surface finish of the panels. Early chemical machining produced pitted and undercut radii that reduced the fatigue strength below that of mechanically machined panels. Reworking the pitted, undercut, land-edge radii increased the fatigue strength by a small amount. Polishing the mechanically machined land-edge radii resulted in a small decrease in fatigue strength because of the undercut radii that were produced. Chemical machining of one titanium alloy produced a variable land edge radius that resulted in a higher fatigue strength than for mechanically machined panels with a constant radius. Remachining of chemically machined land edge radii while maintaining the surface finish and land-edge radii geometry had no affect on the fatigue strength.
Roll Fatigue Tests of Forged ZK60A-T5 Magnesium and 2014-T6 Aluminum Wheels
Authors: Behr R. D. , Campbell S.
Published: August 2009

Fifteen forged ZK60A-T5 magnesium wheels and four forged 2014-T6 aluminum wheels were roll tested at the Wright-Patterson Air Force Base in a cooperative wheel-test program with The Dow Metal Products Co. Magnesium wheels were modified F104 wheels which were redesigned to reduce roll life from over 1000 miles to about 100 miles at a load of 10,000 1b. A load versus roll-life scatter band was established by testing 12 magnesium wheels at loads ranging from 6500 to 12,500 lb. Three aluminum wheels, which were thinner but still 20 per cent heavier than the magnesium wheels, had roll lives comparable to the magnesium wheels; it is concluded that a magnesium wheel can be about 20 per cent lighter than an aluminum wheel and have the same life expectancy. Strain was measured at various locations in wheels being roll tested, and the variation with tire inflation pressure and rolling load was determined. The site of fatigue crack initiation (bead-seat radius) is strained well into the plastic range under normal roll test conditions. Wheel roll lives and strains measured at the bead-seat radius were found to depend upon the ply rating of the tire mounted on the wheels and also upon whether tubes were used in the tires.
Introduction
Authors: Gunia R. B.
Published: August 2009

The papers in this volume represent the first discussion of its kind on the subject of the “Effects of Residual Elements on Properties of Austenitic Stainless Steels.” The authors have enumerated the sources from which some of the residual elements originate and evaluated their effects on the products made of these steels. During the more than fifty years in which these alloys have been commercially produced in the United States, numerous restrictions on the various elements have been written into specifications, often without either technical knowledge or justification, and probably most frequently on the basis of unfounded opinions. Now for the first time, a group of technical experts, metallurgists, and engineers, have presented documented evidence that many of the residual elements have little or no adverse influence on the metal's behavior in the many applications for which this important family of stainless and heat resisting steels is utilized. For the first time also, the technical literature is augmented by this present series of authoritative discussions. It is the consensus that in general only one area will now need additional work and that is in the field of welding. The view is projected in one of the papers in this symposium that at the present time it is not possible to evaluate the beneficial or harmful effects of many of the residual elements in welded structures. In other areas, such as fabricating or resistance to corrosive environments, the data here assembled indicate that many of the elements may indeed be beneficial rather than detrimental. The authors have presented their views clearly and succinctly. They are to be commended for these valuable contributions to the literature in a field where silence has too long been the rule.
Effects of Residual Elements on Cold Rolling and Finishing of Austenitic Stainless Steels
Authors: Pruger T. A. , Blake F. , Valley J. A.
Published: August 2009

It is the purpose of this paper to review the more common residual elements in austenitic stainless steels. Their effects on work hardening, surface, corrosion resistance, welding, etc., will be noted where information is available. An arbitrary limit of 0.05 per cent per residual element will be used as a guide. Experiments and experience at Allegheny Ludlum Steel Corp. with residuals exceeding 0.05 per cent will also be reviewed. It is intended to point out the harmful effects of certain elements and emphasize the satisfactory results obtained with other residuals in standard grades. Residual elements can be grouped into several categories—austenitizers, ferritizers, carbide formers, interstitials, etc. Copper, nitrogen, and cobalt are called austenitizers principally because they promote the formation and stability of austenite. Nickel, manganese, and carbon are other austenite-stabilizing elements and are an integral part of standard analyses. Aluminum, molybdenum, and silicon fall into the category of ferritizers, in that they promote the formation of ferrite. Other elements such as tungsten, vanadium, columbium, etc., can combine with the carbon to form carbides with remaining percentages acting as ferrite formers and going into solid solution. Hydrogen and oxygen are classified as interstitials.
Residual Elements in Austenitic Stainless Steels—The Melt Shop Viewpoint
Authors: Goller G. N.
Published: August 2009

Economics leads to the use of certain raw materials and melting practices in the production of the austenitic stainless steels, thereby establishing an acceptable “normal” level of residuals. This paper classifies the numerous residual elements which have been encountered in these steels, giving some concept of their characteristics as far as melting operations are concerned. These elements get into the steel from such sources as refractories, furnace contamination, home and purchased scrap, alloying materials, and fluxes. Many are influenced by the melting practice. To deviate from current raw material sources and melting practices in order to accommodate a more restrictive requirement with respect to certain residual elements can be very costly. Modern vacuum treating units may be helpful in controlling some of the residual elements.
Effects of Minor Constituents on Irradiation Damage to Austenitic Stainless Steels
Authors: Bement A. L.
Published: August 2009

The effects of residual elements on the service behavior of austenitic stainless steels in present reactor systems are reviewed with respect to alloy stability in the temperature ranges for current and advanced reactor concepts. The stringent demands on these alloys in advanced reactor systems, which require long service life of stressed components under combined neutron flux, high temperature, and reactive coolant environments, are outlined. Changes in phase stability and precipitation reactions caused by atomic displacements at relatively low temperatures are discussed from the background of current neutron damage theory. High temperature nonrecoverable embrittlement of these alloys is described in terms of both carbide precipitation and helium generation mechanisms. Thermal-mechanical treatments have been found to be successful in reducing the magnitude of this embrittlement. In the case of fast breeder reactors, neutronic reactions will cause a significant change in some alloy constituents and will cause the generation of helium and hydrogen gaseous products. Theoretical studies which have considered both the types of structural damage resulting from these neutronic effects in different neutron spectra and the resulting effects of this damage on metallurgical behavior are discussed.
Residual Elements and Their Effect on Applications of Austenitic Stainless Steels in the Power Industry
Authors: Rohrig I. A.
Published: August 2009

Use of the austenitic stainless steels permitted increases in steam temperature in the power industry from 1000 F up to 1200 F. Problems of cracking at welded joints in Type 347 heavy-wall steam piping used at 1050 to 1100 F (566 to 593 C) resulted in changing to Types 304 and 316 steels for pipe. Creep failures in Type 321 superheater tubing have been resolved by use of the Type 321H material. Residual elements had no part in the problems with Types 347 and 321. A study made by the Edison Electric Institute shows that as pressure, temperature, and size of units have increased, operating availability has decreased. The result is a downward trend to 1000 to 1050 F (538 to 566 C) in temperature of new designs. Failures due to corrosion pitting of stainless steel condenser tubes were reported in several plants in 1965. Type 304 tubing used in a few plants as a replacement material in feedwater heaters has a good record. Research to improve the strength of Type 304 shows the beneficial effect of 0.07 to 0.15 per cent nitrogen in improving the rupture strength at 1200 F (649 C). A review of the use of austenitic stainless steels and the experience with the materials shows that the residual elements present in commercial materials have no effect on the use of the austenitic stainless steels in the power industry.
Effects of Residual Elements on the General Corrosion Resistance of Austenitic Stainless Steels
Authors: Scharfstein L. R.
Published: August 2009

A literature review and new experimental data are presented on the effects of residual elements (boron, carbon, nitrogen, silicon, phosphorus, sulfur, aluminum, cobalt, copper, molybdenum, columbium, and titanium) on the general corrosion resistance of the austenitic Cr-Ni stainless steels. Only molybdenum, copper, and cobalt are considered beneficial; boron less than 0.006 per cent may help resist intergranular corrosion; boron greater than 0.010 per cent, silicon, carbon, and sulfur are detrimental, while nitrogen, phosphorus, aluminum, columbium, and titanium may either be “neutral” or detrimental depending upon concentrations, heat treatments, and “cleanness” of the melt.
Weldability of Austenitic Stainless Steels as Affected by Residual Elements
Authors: Linnert G. E.
Published: August 2009

The effects of residual elements in austenitic stainless steels are of considerable importance in welding. Many unusual occurrences suspected to be related to residual elements have been encountered, including cracking, porosity, slag formation, corrosion susceptibility, and embrittlement. Residual elements are difficult to control and trace because the weld metal may accumulate the residual element from such sources as the base metal, filler metal, fluxes, and shielding gases. Because great effort regularly is made to circumvent difficulties through the welding procedure, many phenomena believed to be related to residuals escape investigation and are not documented. Three problem areas of current interest are reviewed: (a) slag formation on weld metal which interferes with the joining process, (b) porosity in weld metal as produced by nitrogen containing compounds in the base metal, and (c) cracking in weld metal and the heat-affected zones. A need is shown for more exacting knowledge of the atomistic distribution of residual elements in the various forms of austenitic stainless steels, such as weld metal and wrought or cast base metal, because their behavior in welding varies greatly with microstructural condition.
Residual Elements in Stainless Steel—General Characteristics
Authors: Heger J. J.
Published: August 2009

Residual elements in stainless steel are introduced during melting and originate from the scrap, the ferroalloys, the deoxidizers, and the furnace atmosphere. Several of the elements, in particular boron, can by themselves or in combination with other residual elements form low-melting eutectics which can affect hot workability and welding characteristics. If present in the steel, the elements vanadium, tantalum, columbium, titanium, and zirconium should be present as carbides or nitrides or both. Boron and cerium should be present as nitrides. Only a few of the elements, namely, cobalt, copper, manganese, nickel, carbon, and nitrogen are austenite formers at elevated temperature. All of the elements with the exception of cobalt (and possibly aluminum) increase austenite stability by lowering the Ms temperature. The formation of sigma and chi phase is enhanced by the presence of aluminum, columbium, molybdenum, silicon, tantalum, titanium, vanadium, and tungsten. The interstitial elements, hydrogen, carbon, nitrogen, and boron have the greatest effect on mechanical properties.
Evolution of Sex-Dependent Gene Expression in Three Recently Diverged Species of Drosophila
Authors: Jiang Zi-Feng , Machado Carlos A
Published: September 2009

Sexual dimorphism in morphological, physiological, and behavioral traits is pervasive in animals, as is the observation of strong sexual dimorphism in genomewide patterns of gene expression in the few species where this has been studied. Studies of transcriptome divergence show that most interspecific transcriptional divergence is highly sex dependent, an observation consistent with the action of sex-dependent natural selection during species divergence. However, few transcriptome evolution studies have been conducted between recently diverged species (<1 MY). Here, we present analyses of sex-biased transcriptome divergence in sexually mature adults of three recently diverged species of Drosophila: Drosophila pseudoobscura, D. persimilis, and D. pseudoobscura bogotana. Data were collected using a custom designed Agilent oligonucleotide. Expression was detected in 12,507 genes. About 80% of the expressed genes show sex-biased expression in each species. Across species, 21% of the transcriptome shows switches between nonsex bias and sex bias, and just 0.9% of the transcriptome shows reversals of sex-biased expression. Over 80% of the expression divergence between species is due to changes in one sex only. About 15% of the expression divergence between species is due to changes in the same direction in both sexes and just 2% is due to changes in both sexes but in opposite directions. In agreement with previous studies, we observe a high level of sex-dependent transcriptome divergence and strong demasculinization of the two arms of the X chromosome in all species. However, in contrast to previous studies we find that male-biased genes do not have higher levels of expression divergence than non-sex-biased genes, and sex-biased genes show higher levels of expression divergence in the alternate sex, suggesting that sex-biased genes endure stronger selection when expressed in the alternate sex.