bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hard-Rolled Aluminum Alloys
Authors: Mattsson E , Lindgren S 
Published: March 2009

In 1955 exposure tests were started with the following architectural aluminum alloys in hard-rolled condition: high-purity aluminum, commercial purity aluminum (with and without 0.14 per cent copper), AlMn1.2 (with and without 0.14 per cent copper), AlMg0.65, AlMg2.5, Alclad (with core of AlMn1.2 and cladding of AlZn1). Panels of the alloys were exposed on five sites in Sweden with rural, marine, urbanmarine, and industrial atmospheres.
After one-, three-, six-, and ten-years' exposure, specimens were taken in and examined with respect to pitting, layer corrosion, and change in mechanical properties.
From the results it may be concluded that the hard-rolled AlMg alloys are well suited for architectural purposes. There is no risk of blistering, and the pitting corrosion resistance is as good as for unalloyed aluminum. With hard-rolled, unalloyed aluminum of commercial purity and AlMn1.2, both without copper, the risk of blistering cannot be disregarded, at least not in a marine atmosphere. Here layer corrosion blisters were formed on the alloys mentioned in most cases already during the first year of exposure. After the initial period, however, they generally developed very slowly. One way to overcome the susceptibility to blistering apparently is to add about 0.1 to 0.2 per cent copper. Another remedy might be to use alloys in half-hard condition, which is common practice. The alclad surface developed a rather rough appearance.
It may be concluded that all the alloys tested will last for several decades in outdoor use, as far as the mechanical properties are concerned. Corrosion, however, may affect the appearance by pitting, blistering, roughening, and discoloration. Often, however, such “aging phenomena” may be regarded as an attractive patina.
Performance of Aluminum Alloys at Other Test Sites
Authors: Ailor WH 
Published: March 2009

The well documented pattern of corrosion behavior for aluminum alloys is confirmed for the seven-year exposures at Corpus Christi, Tex.; Richmond, Va.; McCook, Ill.; and the Kure Beach, N. C., 800-ft site. A decrease in the corrosion rate, as determined by weight loss, was evident for all sheet alloys after about the second exposure year. Likewise, the depth of pitting decreased with time: very slight increases in depth were noted between the second and seventh years in most cases.
Results indicate that the McCook site is the most severe, with the Richmond location, the Corpus Christi exposure, and Kure Beach 800-ft site in order of decreasing severity.
The value of cladding basic alloys such as 3003 and 6061 was demonstrated again. The claddings effectively protected the core alloys from pitting and general corrosion and the clad alloys showed negligible changes in mechanical properties at all sites after seven years.
Other than the 2024 aluminum-copper alloy which showed intergranular corrosion for some hard tempers at the most severe sites, all alloys showed pitting corrosion to some extent. Maximum pit depths included 14.7 mils for the 2024-T36 alloy, 10.0 mils for the 5154-H34 aluminum-magnesium alloy, 5.2 mils for the aluminum-magnesium silicide alloy 6061-T6, and 6.3 mils for the high-purity aluminum sheet. With the exception of the 2024 metal, these deepest pits occurred at the McCook site. The deepest pit found on the Kure Beach 800-ft site panels measured 6.1 mils, and the deepest pit for most Corpus Christi panels was 5.4 mils (2024 alloy panels having some intergranular attack had measured pits as deep as 14.7 mils).
A corrosion rate of 0.175 milligrams per square decimeter per day (mdd) for 2024-T36 alloy at McCook was the highest found. If we exclude the 2024 alloys, no corrosion rate greater than the 6061-T6 rate of 0.125 mdd was found. High purity aluminum showed rates from a low of 0.004 mdd at Kure Beach to 0.044 mdd at McCook.
Effect of One Per Cent Copper Addition on the Atmospheric Corrosion of Rolled Zinc
Authors: Dunbar SR 
Published: March 2009

Atmospheric corrosion characteristics of a commercial rolled zinc alloy containing 1 per cent copper and one unalloyed grade were evaluated after two- and seven-year exposures under the Committee B-3 1957 test program on atmospheric corrosion of nonferrous metals. Comparisons were made with the behavior of three unalloyed grades included in a 20-year Committee B-3 program initiated in 1931. The usefulness of tension tests for determining corrosion rates was explored in both programs.
Weight loss determination appears to be the most reliable means of assessing corrosion rates for zinc. Good agreement among zinc corrosion rates in the two programs was obtained. Zinc composition was found not to significantly influence corrosion rates.
Pitting occurred in the copper bearing alloy most probably as a result of local galvanic action. The pit depth-total penetration ratio decreases as total penetration increases. Tensile properties of zinc were not significantly affected after seven-year exposure. Therefore, pitting is not believed to be of practical importance.
Tension tests are not useful for evaluating corrosion damage in zinc unless a means of compensating for aging effects can be found.
Measurement of Atmospheric Factors Affecting the Corrosion of Metals
Authors: Guttman H , Sereda PJ 
Published: March 2009

Atmospheric factors, namely, time of wetness of corroding metal panels, panel temperature, and atmospheric sulfur dioxide and atmospheric chloride content, were measured at four inland and three coastal North American test sites while corrosion data for steel, copper, and zinc were being developed. Corrosion losses experienced by panels of these metals which were exposed at different times of the year for similar periods of time showed considerable variation at all sites.
Statistical analyses show conclusively that the atmospheric factors measured completely control the rates of corrosion at all sites for at least the initial month. For longer periods of time control of the corrosion process remains with the atmospheric factors in some cases, and in others it is gradually transferred to factors related to the changing surface conditions resulting from accumulation of corrosion products and foreign agents.
At the sites where the atmospheric factors control corrosion, the empirical equations developed enable one to predict the corrosion losses of steel, copper, and zinc from a knowledge of the atmospheric factors. They also now make it possible to account for variations in observed corrosion losses experienced by panels exposed at different times of the year.
A Study of Local Stresses Near Surface Flaws in Bending Fields
Authors: Marrs GR , Smith CW 
Published: March 2009

A set of photoelastic experiments utilizing stress freezing and slicing techniques was conducted in order to estimate stress fields near naturally grown deep surface flaws in plates under approximately cylindrical bending fields. Geometries investigated ranged over crack depth to crack length ratios of approximately 0.25 to 0.45 and over crack depth to plate thickness ratios of approximately 0.35 to 0.45. Results were compared to an approximate theory devised by F. W. Smith [6]. In order to achieve a comparison consistent with linear elastic fracture mechanics, the effect of the experimental non-linear zone due to finite rotations very near the crack tip was minimized by extrapolating across it. The plastic zone correction in the Smith theory was neglected.
Results indicated that the Smith theory will predict the proper order of magnitude of the stresses near the crack border both in the region of maximum crack penetration and where the crack border intersects the tensile surface of the plate. However, in all tests the predicted stresses were lower than the experimental stresses in the former region and higher than the experimental stresses in the latter region.
Fatigue Threshold Crack Propagation in Air and Dry Argon for a Ti-6Al-4V Alloy
Authors: Bucci RJ , Paris PC , Hertzberg RW , Schmidt RA , Anderson AF 
Published: March 2009

Fatigue crack propagation experiments on a Ti-6A1-4V alloy were carried out within the framework of linear elastic fracture mechanics. Crack propagation results encompassing a wide range of fatigue crack growth rates, Δa/ΔN, and stress intensity range, ΔK, were plotted in the conventional manner (that is, log-log plots of Δa/ΔN as a function of ΔK) for studies conducted in room temperature air and dry argon environments. Corresponding fatigue striations formed in both environments were measured and compared with macroscopic crack extension rates.
Examination of very low fatigue crack propagation rates at low ΔK levels disclosed a stress intensity threshold level below which Mode I fatigue crack propagation became insignificant.
In a limited investigation at very low fatigue crack growth rates, the fatigue threshold levels were observed to decrease with increasing stress ratio, R (ratio of σmin/σmax= Kmin/Kmax). The influence of stress ratio also was observed at ΔK levels above the threshold; cyclic crack growth rates increased for the increased values of R. However, for the ranges of ΔK, R, and growth rate considered in this work, the R ratio influence appeared most pronounced at the lowest growth rates and lessened with increasing ΔK.
Comparable fatigue crack growth tests (R = 0.33) conducted on the Ti-6A1-4V alloy in air and inert dry argon at room temperature yielded almost identical results for cyclic crack growth rates encompassing those associated with the fatigue threshold (Δa/ΔN ≃5 × 10-9 in./cycle) upward past 10-5 in./cycle. Within this range, the fracture surface morphology changed from a cleavage-like appearance at threshold levels to a typically striated and dimpled appearance at higher growth rates.
No significant difference in fatigue crack growth rate behavior was reported for Ti-6A1-4V specimens tested in either the STA (solution treated and aged) or STA + annealed heat treated condition.
Fundamentals of Radiation Effects Testing
Authors: Sinclair EE , Simmons JM , Zwilsky KM 
Published: March 2009

The basic effects of irradiation, such as transmutation re-actions, hardening, void formation and high temperature embrittlement are reviewed. Testing for these effects takes the form of pre-post testing as well as in-reactor observations. Pre-post testing consists of measuring a property out-of-reactor, and measuring the same property after the material has been exposed to the neutron environment. Although changes in properties of a material can be determined before and after irradiation, the influence of a neutron flux on rate processes such as creep must be determined in-pile.
Characterization of the reactor environment including neutron dosimetry and temperature measurements are discussed, and examples of predictive testing of materials for reactor fuels, cladding, components and pressure vessels are reviewed.
Fatigue Life Predicton for Weldments with Internal Cavities
Authors: van der Zanden AM , Robins DB , Topper TH 
Published: March 2009

A method evolved for determining the local stress-strain response of notched members is extended to predict fatigue resistance of weldments with internal cavities. It is applied to both stress-relieved samples and as-received weldments. Test results from stress-relieved samples show good agreement with life predictions based on prestrained fully reversed strain controlled smooth specimen tests.
A calculation of inelastic deformations induced in the weld metal of as-received samples indicates that localized stresses will be of yield stress magnitude on the first load application. A fatigue parameter then incorporates ensuing mean stress effects. Good life predictions obtained in this application, where the local stress history is complex, demonstrate the adequacy of this method of analysis.
Stress Corrosion Cracking of Copper Metals
Authors: Thompson DH 
Published: March 2009

Four factors that cause stress corrosion cracking are sufficient stress, a suitable corrodent, a susceptible alloy, and time. The nature and sources of both applied and residual stress are discussed. The sources of residual stress that are peculiar to the brass industry are described. The copper (Cu) metals are listed in order of their relative susceptibility to stress corrosion cracking. Zinc (Zn) in Cu contributes to the probability of its cracking; nickel (Ni) in Cu metals tends to inhibit it. Stress corrosion cracking is not instantaneous, so time is a factor in its occurrence. Various methods for the prevention of stress corrosion cracking are discussed. Some examples of stress corrosion cracking in service are described. Probability is discussed in relation to its role of predicting the stress corrosion cracking of Cu metals. Testing of Cu metals for their resistance to stress corrosion cracking may employ loops or U-bends. Applied stress may be effected by dead weight loading or by the use of springs. Corrodents may be chemical solutions, natural environments (atmosphere, sea water) or exposure to service environments. The metallographic appearance of stress corrosion cracks in Cu alloys is described as are the crack paths in brass and in other metals.
Liquid metal embrittlement is similar to stress corrosion cracking but is thought not to be identical. The similarities and differences are discussed. Mercury (Hg) is used to test for the presence of residual stress in brass, however Hg is an extremely dangerous metal in contact with any Cu alloy. The possible sources of Hg are mentioned. A chiller which failed by Hg cracking is described. Other liquid metals may cause cracking of Cu alloys including low melting alloys which are used in tube bending.
Overview of Corrosion Cracking of Titanium Alloys
Authors: Feige NG , Covington LC 
Published: March 2009

Titanium depends upon the protective nature of a surface film, essentially an oxide, for its corrosion protection. Stress corrosion cracking results when the local breakdown of that film occurs causing a significant shift in the composition of the electrolyte and establishing electrochemical currents in the restrictive area which combine to prevent repassivation of the site.
Extensive testing has been conducted to define the threshold stress (KIscc) to sustain the electrochemical reaction. A large variation is seen between alloy, heat treatment, and mill conversion practice which can be related back to the notch and its strain conditions and the sensitivity of the alloy to the electrolyte present in the notch area. It has been demonstrated by rapid freezing of the reaction site that the electrolyte is a highly acidic reducing environment, and is in such a region of the Pourbaix diagram that the passive film will not reform. The electrochemist can further define the alloys susceptibility by evaluating the anodic current density in the pit area to sustain pitting and the cathodic current density to charge hydrogen. The pH of the electrolyte controls the hydrogen uptake efficiency at the cathodic site. Hydrides, formed at the local cell cathodic site under subsequent anodic control will react and pit at low anodic current density.
Stress corrosion cracking in the titanium alloys is the ability of the structure or test configuration to sustain by a moving crack front an actively corroding local site of a nonpassivating electrolyte. The classical argument as to whether the halogen or hydrogen are the cracking species is obscure, as both are interacting to sustain the reaction.
Friction-Induced Ignition in Oxygen
Authors: Jenny R , Wyssmann HR 
Published: March 2009

The friction-induced ignition of structural materials in oxygen has been investigated. A test arrangement has been designed that allows basic data for the oxidation reaction rate to be determined for various materials or pairs of materials. The rate at which oxidation energy is released at the rubbing interface is obtained from the difference in measured friction power necessary to produce the same interface temperatures in tests with oxygen and an inert gas. These results are then correlated by the Arrhenius rate law, allowing the oxidation reaction rate factors for the different materials to be determined.
The theoretical simulation of the ignition process for the test arrangement using these data is in good agreement with the observed experimental results. This suggests that the geometry, ambient temperature, and gas velocity, which have a primary effect on heat dissipation are adequately taken into account by the theoretical model.
In addition to the collection of these basic data, the test allows materials to be classified for oxygen compatibility under friction simply by means of comparing the axial load necessary for ignition. Of the pairs of materials tested, Monel was found to give the highest ranking, followed by stainless steel/cast iron and bronze. The propagation of combustion after ignition was smallest with Monel, followed by bronze, and was largest for stainless steel/cast iron.
Design Criteria for Acoustic Emission Experimentation
Authors: Tatro CA 
Published: March 2009

Acoustic emission experiments that can be performed in the laboratory using a single transducer and involving specimens or simple components are discussed. The emphasis is on experimental design rather than on single experiments or results produced. The experiments described are restricted to those where application of mechanical load is used to condition the material, and where commercially available equipment is adequate for instrumentation.
The magnitudes and characteristics of the acoustic emission response are described. The compromises in signal detection and data acquisition methods follow from this description. Those aspects of experimental design which are most likely to be foreign to the new user of acoustic emission techniques are pointed out, as are ways to assure that a proper design has been achieved. Results of an experiment which reveals the unique power of acoustic emission technology to reveal subtle changes in material are given as an example.
Acoustic Emission Testing of Pressure Vessels for Petroleum Refineries and Chemical Plants
Authors: Cross NO , Loushin LL , Thompson JL 
Published: March 2009

Acoustic emission testing (AET) is being used by fracture mechanics and nondestructive test engineers to establish the design adequacy, structural integrity, and operating safety of petroleum and petrochemical equipment. Used as a tool in the application of fracture mechanics concepts, AET of heavy wall pressure vessels during hydrostatic testing also provides the means of assuring against catastrophic brittle fracture by locating growing defects. The state-of-the-art in developing effective electronic instrumentation and flaw site triangulation methods has reached the point where AET should be considered competitive with other, more commonly specified test methods.
For onstream surveillance, AET has the potential for the detection of service induced flaws and for detecting potentially detrimental changes in material properties. The amplitude and frequency content of environmental noise can however, limit applications of this type. Although techniques are available for minimizing the reception of unwanted electrical and mechanical sources of noise, additional effort is needed in this area to facilitate widespread inservice use.
Other areas requiring further research and development effort and the development of standards, include flaw signature analysis, signature analysis characteristics for various materials, simplified instrumentation, acoustic parameter selection, the effect on signals of environmentally induced materials property changes, and data display.
The Broad Range Detection of Incipient Failure Using the Acoustic Emission Phenomena
Authors: Balderston HL 
Published: March 2009

The broad range detection of incipient failure in structural, mechanical, hydraulic, pneumatic, electrical, and electronic systems is based upon the detection of the two basic causes of failure. These causes are structural degradation and chemical contamination occurring in the structure of the material of which the systems listed above are composed. The detection of incipient failure allows maintenance to be programmed at the convenience of the user, thus preventing down time of equipment during use periods.
The acoustic emission phenomena are employed in the detection of incipient failure in all types of equipment covered in this report. Specifically, the examples chosen are structural, mechanical, pneumatic and hydraulic components, subassemblies, or specimens as applicable. From these examples the broad range incipient failure detection concept based on the acoustic emission phenomena is developed. The experiments covered include detection of incipient failure in bearings, hydraulic assemblies, pneumatic subsystems, stress corrosion in aluminum, ductile tensile failures in carbon steel, 4330M steel, and in boron-epoxy composite material.
Application of Topological Concepts in Stereology
Authors: Steele JH 
Published: March 2009

The quantitative characterization of microstructure involves consideration of the topological properties of the physically distinguishable 3-dimensional regions (for example, phases or grains) which constitute it. The two topological properties of primary interest are the connectivity and number of separate regions. These topological concepts, their measurement, and their application in describing sinter bodies will be discussed.
The application of topological relationships to polycrystalline microstructure is extremely important in quantitative characterization of grain shape and boundary configurations. In this case, the properties of space filling, simply connected, polyhedral regions will be utilized to develop a consistent set of equations relating the number of grains, faces, edges, and vertices to the average configurations of these features. The implications and limitations upon polycrystalline aggregates which result from these equations will be presented. The measurement of these properties and their application in describing normal grain growth will also be discussed.
Automatic Methods for Analysis of Microstructures
Authors: Moore GA 
Published: March 2009

From the viewpoint of materials engineering and quality control the significant aspects of the microstructure of a material as a whole constitute a gestalt which controls mechanical behavior. This gestalt can be specified by six stereologically valid parameters measuring phase percentage, size and spacing of particles, variability among portions of the material, general anisotropy, and degree of patternness. Raster scanning devices of either the mechanical or television type are intrinsically capable of easily measuring these six parameters. Provision for each is available in at least one of the present television scanners. Minor changes are desirable to provide this common set of measurements with all instruments and to improve accuracy.
In contrast, microarchitectural processes which identify, measure, and selectively count individual object sections require massive programming effort and areinefficient and time consuming in present computers. Selective specimen preparation and human designation of objects are preferable to machine identification. Some proposals for more efficient and more human-like machines are mentioned. Materials engineers should try to avoid these difficult processes whenever feasible.