bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Present Status of Metallography
Authors: Gray R. J. 
Published: September 2009

The metallographer has a prime responsibility as a member of a metallurgical or, in many laboratories, a materials team. In addition to his duties of specimen preparation and assistance in interpretation of microstructures, he must keep abreast of new techniques and developments or develop his own as they are needed.
The Space Age and particularly the problems of the Nuclear Age have climaxed the obstacles of this field. The daily remote handling of highly radioactive or toxic materials or both, which only a few years ago were textbook curiosities, has removed the “touch” formerly considered an essential part of the operation. Almost all the preparation and investigational steps performed in a conventional laboratory can be carried out by remote operations.
New techniques in revealing the microstructure in color by staining and anodizing are becoming very popular. Although the colors usually produced have enhanced the art tremendously, the benefit is not confined to beauty. Reaction mechanisms such as corrosion and diffusion as well as variations in crystallographic orientation have been understood more clearly from color interference patterns or basic color changes. This information can be recorded in the laboratory by adopting the present techniques in color photography.
The development of commercial equipment allied to the objectives of the metallographer has been a big help. The microprobe analyzer permits essential analyses of microscopic areas. Hot stage microscopy equipment allows us to view grain boundary movements and other features formerly confined to the imagination. Quantitative data are obtainable now in a fraction of time formerly required. Along with this development of commercial equipment, there have been “inlab” modifications which show great promise.
Many challenges remain and new ones can be seen in the near future. One in particular is the uncertainty of availability of well trained or professional metallographers. Current trends in metallurgy and materials science curricula seem to be decreasing the amount of metallographic training. If this trend continues, there will be an even greater requirement for “professional metallographers.”
Development of Austenitic Stainless Steels with Improved Resistance to Elevated-Temperature Irradiation Embrittlement
Authors: Bloom E. E. , Weir J. R. 
Published: September 2009

The effects of titanium in concentrations of up to 0.5 weight percent on the tensile and creep-rupture properties of unirradiated and irradiated types 304 and 304L stainless steel have been investigated. It was found that within this range an alloy containing 0.15 to 0.25 weight percent titanium has optimum postirradiation ductility. When this alloy is annealed 1 h at 925 C prior to irradiation, the postirradiation ductility is essentially independent of tension test temperature and increases as the strain rate is reduced in creep-rupture tests at 700 C. In contrast, the postirradiation ductility of standard types 304 or 304L stainless steel heat treated and irradiated under the same conditions decreases with increasing temperature or decreasing strain rate.
These effects appear to result primarily from the effect of titanium on the intergranular fracture process, making crack initiation or propagation, or both, more difficult and thus reducing susceptibility to the high-temperature irradiation embrittlement phenomenon.
Effects of Yttrium on the Structure and Post-Irradiation Tensile Properties of an Iron-Chromium-Aluminum Alloy
Authors: Roberts A. C. , Harries D. R. , Arkell D. R. , Dewey M. A. P. , Hughes J. D. H. 
Published: September 2009

The effects of 0.86 percent yttrium on the structure and elevated temperature tensile properties of unirradiated and thermal reactor irradiated Fe-15Cr-4Al ferritic steel have been investigated. Yttrium reduces the grain coarsening tendencies of this alloy; the yttrium is present mainly as YFe 9 precipitates within the grains and generally aligned in the direction of rolling. Autoradiographic examination shows that the boron is concentrated at the grain boundaries of the yttrium free alloy, while the boron is primarily associated with the YFe 9 phase in the 0.86 percent yttrium alloy.
The tensile ductilities of the 0 percent yttrium alloy at temperatures ranging from 700 to 950 C are markedly reduced after irradiation at 50 or 650 C; the magnitude of the embrittlement is somewhat greater after irradiation at the higher temperature. This irradiation induced embrittlement is associated with failure along the grain boundaries. There are no significant reductions in the high-temperature ductilities of the 0.86 percent yttrium alloy after irradiation.
Optical and thin film electron microscope examinations suggest that the mechanism of the irradiation induced embrittlement in the 0 percent yttrium alloy is similar to that proposed for austenitic steels, namely, the stress induced growth of grain boundary helium bubbles produced as a result of the B10(n,α)Li7 reaction. The absence of a high-temperature irradiation embrittlement effect in the 0.86 percent yttrium alloy is considered to be primarily because of the association of most of the boron with the YFe 9 phase and, hence, the retention of the helium within the grains.
High-Temperature Embrittlement of AISI Type 316 Austenitic Stainless Steels after Irradiation
Authors: Weisz M. , Malkin J. , Erler J. , Andre J. P. 
Published: September 2009

The results presented below are related to potential cladding materials for fast reactor fuel elements, that is, austenitic stainless steels and precipitation-hardened nickel alloys.
These materials were irradiated to a dose of 3 × 1021 nvt (E &gt; 1 MeV) in different thermal reactors and to a dose of 1.6 × 1022 nvt (total dose) in a fast reactor. The irradiation temperature was about 700 C in thermal reactors and about 500 to 600 C in a fast reactor. After irradiation, tension tests and uniaxial stress rupture tests were performed at temperatures in the 600 to 800 C range.
For all alloys, high-temperature tests after irradiation have shown a more or less pronounced embrittlement, not recoverable by any post-irradiation annealing. This embrittlement is associated with intergranular wedge-type cracks initiating at triple points. For a given alloy, at a given temperature, the lower the rate of deformation, the more pronounced the embrittlement.
For Type 316 austenitic steels, we observed that the radiation induced hardening was low and disappeared at a maximum temperature of 800 C. The embrittlement was associated with a decrease in the nonuniform part of the elongation in tension tests and with a decrease in the elongation and duration in the tertiary stage of stress-rupture tests. Two types of factors were studied: 1. Those concerning the structural parameters: grain size, precipitation, prestraining, and chemical composition. 2. These concerning the actual conditions of irradiation.
Rust Inhibitors—Their Evaluation and Performance
Authors: von Fuchs George H 
Published: September 2009

The primary purpose of turbine oil rust inhibitors is to form water-repellent stable films on those exposed iron surfaces within the lubricating system and governor mechanism of steam turbines with which the lubricant comes in contact. Such additives are normally evaluated by ASTM Method D 665, but passing this test does not always assure satisfactory field performance. One reason is that some rust inhibitors, particularly those of the soap type, form loosely bound protective films which prevent adhesion of water only as long as it occurs suspended in an oil phase, but when the oil is absent, such films soon fail. A method to test the hydrolytic stability of rust-protective films is to expose them to the direct action of a continuously agitated water phase.
Another rust test not normally specified for turbine oils is the Naval Research Laboratories static water drop test. A greatly accelerated version of the NRL test is the so-called catechol test, based on the fact that the first corrosion product of iron is colorless, water-soluble ferrous hydroxide which in the presence of catechol is immediately converted to highly colored ferrous catecholate.
When in the D 665 rust test, distilled water is replaced by 0.1 N hydrochloric acid only those additives will stand up which form a closely packed chemically and hydrolytically stable film. The performance of the rust inhibitor is determined by the structure and size of its hydrophobic side chain as well as by the type and strength of the chemical bond formed with the reactive polar group of its molecules. In the complete absence of water, the reaction of rust preventives with iron surfaces is greatly retarded or even inhibited.
Rust inhibitors should also be subjected to other test criteria including their effect on oil oxidation. Even some of the best rust inhibitors will often seriously reduce the oxidation stability of the oil to which they are added because of their tendency to dissolve catalytically active metals such as copper and iron. The ideal rust inhibitor should have no harmful effects on oil life. Other test criteria to be considered are the effect rust inhibitors may have on the demulsibility, foaming and air-release characteristics of the oils; also their hydrolytic stability, chemical purity, and their compatibility with other oil additives.
General Motors Rear Axle Lubricant Recommendations
Authors: Hunstad Norman A. 
Published: September 2009

A solution to the problem of recommending rear axle lubricant to the car owner requires the availability of good quality products, together with identification of these products.
Rear axle lubricant of the MIL-L-2105B quality level is needed for General Motors cars. Some GM divisions will advise car owners to use MIL-L-2105B lubricants in 1963 cars. Such lubricants should be made available at retail outlets, and they should be clearly identified.
Designing and Fabricating with Elastomers
Authors: Konkle G. M. 
Published: September 2009

The term elastomer or rubber is applied to any material which is capable of recovering from large deformations quickly and forceably. A vast number of materials of widely different compositions fit this description. Polymers vary from products of the rubber tree to synthetic polymers consisting largely of the element sulfur. Finished products contain two to twelve ingredients in addition to the basic polymer. Each product differs in properties including physiological reactions.
The physical properties of a rubber part are determined by the type of polymer, the other ingredients used, and, to a lesser extent, by the fabricating technique. Proper choice of materials is essential for successful performance. The complex requirements of surgical implants make this a difficult and complicated problem which requires the combined efforts of medical specialists and elastomer experts.
Rubber can be fabricated into a large variety of useful shapes. Complex shapes of closely controlled dimensions can be formed by molding. Shapes of uniform cross section can be made continuously by extrusion. Rubber can be bonded to metal or coated on fabric for increased strength and stiffness. It can be made into sponge or foam of varying degrees of porosity.
Resistance of Polymers to Degradation
Authors: Atlas S. M. , Mark H. F. 
Published: September 2009

Several factors contribute to the rate of degradation of organic polymers under the influence of chemical reagents such as acids, bases, oxygen, or ozone, and of micro-organisms or enzymes:
1. The presence and frequence of chemical bonds which react in principle with these ingredients. These are eventually severed by such action. Bonds of this type are: -C-O-, -C-S-, -C-N-, -C=N-, C=C, and -Si-O-, in contradistinction to -C-C-, which is much more difficult to attack.
2. The atoms or groups in the nearest proximity of these sensitive bonds which either activate or protect them. Such atoms or groups are F, Cl, OH, NH2, COOH, CH3, CF3, etc.
3. The supermolecular character of the polymer: oriented, amorphous, crystalline, folded, crosslinked, etc., which does not affect the intrinsic chemical reactivity of the sensitive bonds but influences very profoundly their accessibility and, therefore, the rate of actual degradation.
The discussion of these three factors gives a reasonable explanation of polymer stability, offers useful working hypotheses for improvements, and stimulates the proper selection of stabilizers.
Fatigue-Crack Growth and Propagation in 2.5Nb Zirconium Alloy Pressure Tubing
Authors: Pankaskie P. J. 
Published: September 2009

Tubes of 2.5Nb zirconium alloy were fatigued in the tension-tension mode by cyclic internal pressures to cause axial crack growth and unstable fractures at room temperature. Pressure-cycle rates ranged from 400 to 3000 cph. Both the cold-worked and heat-treated conditions, before and after hydriding (200 to 300 ppm H2), were investigated. Exploratory tests were done to determine the effect of the axial length of the surface-stress-intensifying defect on fatigue-crack initiation, growth, and critical length at unstable fracture.
From short (≤tube-wall thickness) length defects, fatigue-crack initiation and growth will occur at nominal peak hoop stresses equal to or less than the estimated endurance limit (∼25,000 psi). For fatigue cracks initiated at the outer diameter surface, the shape of the crack front is semicircular. The number of stress cycles required to initiate fatigue cracking at the surface is inversely proportional to the square of the surface-defect length. Crack-growth rates, for non-hydrided tubing are proportional to (ΔK)5, and to (ΔK)4 after hydriding. There was a tendency for the critical crack length at unstable fracture to decrease with an increase in the number of fatigue cycles required to initiate fatigue cracking.
The fracture toughness of the heat-treated tubing before hydriding is less than for the cold-worked condition either before or after hydriding, and after hydriding the fracture toughness is further reduced.
The Effect of Neutron Irradiation and Cold Work on the Strain-Aging Behavior of Zircaloy-2
Authors: Veevers K. , Rotsey W. B. , Snowden K. U. 
Published: September 2009

The strain-aging behavior of annealed Zircaloy-2 in vacuum was studied as a function of deformation temperature, integrated fast-neutron dose, and degree of cold work. Strain aging occurred in the temperature range 200 to 500 C. Transmission electron microscopy showed that in the temperature range 300 to 450 C, dislocations were arranged in a cell structure, and that at 500 C two-dimensional hexagonal dislocation nets were present. Between 200 and 400 C, the strain aging was found to be due to the presence of oxygen; however, the origin of the strain aging between 400 and 500 C was not identified.
At 300 C the strain aging decreased with increasing neutron dose and decreasing amounts of prior cold work. Post-irradiation annealing experiments between 400 and 600 C increased the yield stress of the material at 300 C after irradiation at 325 C.
The Significance of Irradiation-Induced Creep on Reactor Performance of a Zircaloy-2 Pressure Tube
Authors: Watkins B. , Wood D. S. 
Published: September 2009

Zircaloy-2 has been used for pressure tubes in water reactors which operate in the temperature range 250 to 300 C. Irradiation enhances the creep rate under these conditions to such an extent that design must be based on creep rupture.
Insufficient data are available to allow a Larson-Miller extrapolation of the in-reactor creep-rupture strength, and in its place a limiting creep-strain criterion is proposed. The use of a strain limit in design of pressure tubes is discussed and both tubular and uniaxial creep-rupture data are presented. These show that the time to reach 2 or 3 percent strain is only about half the time to failure. Irradiation creep-rupture data are presented which indicate that irradiation substantially increases the strain at which tertiary creep commences and it is suggested that irradiation increases the rupture ductility.
Assuming that the in-reactor creep rate does not decrease with increase of testing time the anticipated creep strain under design conditions is of the order of 2 percent. This is well within the limit which could lead to operational restriction and the time to reach 2 percent strain is about half the time to reach failure in out-of-reactor creep-rupture tests. Thus even with this pessimistic approach there is no risk of a creep-rupture failure under design conditions.
Failure of Pressurized Zircaloy Tubes During Thermal Excursions in Steam and in Inert Atmospheres
Authors: Emmerich K. M. , Juenke E. F. , White J. F. 
Published: September 2009

This work is part of a general study on the behavior of Zircaloy clad-UO2 fuel elements during a loss-of-coolant accident to a water-cooled industrial power reactor. The fuel pins have an internal pressure due to fission gases and may or may not be exposed to steam during the thermal excursion. The energy from the nuclear heating (nuclear afterheat) plus heat from the metal-water reaction may cause the reactor core to experience rapid heat-up to about 1400 C before emergency core-cooling systems become effective in reducing the core temperatures to below the normal operating temperatures. Analysis of such an incident requires an understanding of the mode of failure and the effects of internal pressure, rate of heating, and oxidation.
The temperature of failure for Zircaloy cladding material, heated in an inert atmosphere, was determined for different heating rates for tension specimens of sheet stock under constant load and for tubes with constant internal pressure. The temperature of failure (that is, 34 percent expansion for the tubes, and rupture for the tension specimens) was found to be heating-rate sensitive with higher failure temperatures occurring at higher heating rates. An analytical expression relating applied stress, the heating rate, the true strain at failure, and temperature of failure was derived through analysis of the data from these tests. The activation energy for second-stage creep in Zircaloy-4 obtained from this analysis is 78.5 kcal/mole.
Pressurized tests in a steam atmosphere were made at pressures from 0.040 to 0.141 kg/mm2 (57 to 200 psig) at heating rates from 0.1 to 300 C/s. Steam oxidation caused an increase in the temperature of failure. In addition, at low heating rates and low internal pressures the mode of failure changed from ductile failure (34 percent expansion) to brittle failure (burst). High pressures and high heating rates showed failure behavior similar to that observed in an inert atmosphere.
Dynamic and Static Resistance of Cohesive Soil 1846–1958
Authors: Housel William S. 
Published: September 2009

A review of the research and writing since the early work of Collin (21)2 about 1846 shows that evaluating the dynamic and static resistance of soil has always been recognized as a problem of major importance by engineers and research workers in soil mechanics. In retrospect, it would appear that Collin was many years ahead of his time in his clear perception of the basic elements of the plastic resistance of cohesive soils. His recognition of the transient nature of temporary dynamic reactions and the primary importance of permanent static resistance is just beginning to be recognized by many research workers of the present era of modern soil mechanics. In the author's opinion, it is more than coincidence that Collin found that the permanent resistance of clay soil in his investigations bore approximately the same ratio (24 to 34 per cent) to the instantaneous or temporary resistance that has now been found as the ratio (25 per cent) between the yield value from the ring shear test and the ultimate shearing resistance from the 5-min unconfined compression test.While there is general recognition of the increased resistance of plastic clay soils under rapid rates of loading and the control methods necessary to evaluate time effects, there are very few test procedures which clearly exercise such systematic control of variables. The interpretation of shearing resistance tests is further complicated by a failure to define and separate the incompatible soil reactions due to cohesion and internal friction and to eliminate consolidation effects caused by application of normal pressures in shear testing.In a review of the research program at the University of Michigan, three methods of measuring the permanent static shearing resistance of soils were presented with corroborative data cited from practical applications. These methods were: (a) incremental loading at constant time intervals, followed by extrapolating rates of deformation back to a zero rate to determine the yield value; (b) the determination of minimum and maximum soil resistance coefficients derived from settlement and stress reactions in linear equations for bearing capacity; and (c) the determination of the elastic properties of piles and supporting soil to determine loads carried at the elastic limit. Both of the last two determinations have been correlated with yield values determined by extrapolation of settlement rates with good agreement.All three methods have been correlated with field observations by practical application in design and construction over a period of years, with results of this experience having been reported in references cited and summarized in the paper. Further observations of the dynamic resistance of soil are presented in connection with stability analyses of differential loading of soil masses where progressive displacement on a large scale is involved. While typical examples were given, the large volume of such data requires more space for presentation than is available in this paper and is a subject for future publication.
Effect of Particle Shape and Texture on the Strength of Noncohesive Aggregates
Authors: Morris Henry Clifton 
Published: September 2009

The strength and stability of aggregate such as gravel or crushed rock do not depend upon the crushing strength of the constituent particles but upon the shape and surface texture of the individual particles. The relative importance of these two factors was investigated experimentally in triaxial compression and in a new angle of repose apparatus. The shape and surface texture of selected aggregate were varied by abrasion and by immersion in acid. The size of particle was held constant at approximately ⅛ in.
A plot of strength against roughness indicated that strength increases with roughness to an optimum point beyond which an increase in roughness is accompanied by a decrease in strength. Specimens were tested at the maximum densities attained under standardized conditions of vibratory compaction. It is inferred that, other factors being held constant, roughness in excess of the critical value impedes the development of optimum structural arrangement of the constituent particles.
Test data for all materials tested, including pumice, crushed bricks, basalt, and river gravel, fell on the one curve, and all exhibited the same strength for the same degree of roughness, regardless of mineral composition. It was conclusively demonstrated that so-called “tough” and “hard” materials possess little if any strength advantage over relatively soft and friable materials, unless they differ in roughness.