bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluating a Service-Exposed Component's Mechanical Properties by Means of Subsized and Miniature Specimens
Authors: Lucon E , Bicego V , D'Angelo D , Fossati C 
Published: March 2009

Estimating the mechanical properties of a service-exposed component in a quasinondestructive manner implies sampling as little material as possible from the component itself. Different subsized or miniature specimens to be employed in the various fields of mechanical testing are presented and discussed: 1. Cylindrical specimens with circumferential crack for fracture toughness testing in the brittle regime and miniature disk-shaped specimens for the upper-shelf ductile regime. 2. Miniature reconstructed specimens for residual creep strength evaluation by means of isostress temperature-accelerated tests. 3. Small-size specimens for low-cycle fatigue testing with enhanced cycle frequency.
Data significance and transferability to actual components, as well as accuracy of results, are discussed. Particular emphasis is devoted to usually favorable comparisons obtained with respect to larger, conventional specimens considered by ASTM test standards.
A Novel Miniature Tension Test Machine
Authors: Sharpe WN , Fowler RO 
Published: March 2009

Tensile stress-strain curves can be measured on specimens with an overall length of 3 mm using this new approach. The square test section of the specimens is 0.2 mm on each side.
The load frame is made from stainless steel by electrical discharge machining (EDM) and is 20 mm wide by 12 mm high and 3 mm thick. Load is applied and measured with an external translation stage and the load cell connected to the load frame with a fine wire. The load frame has wedge-shaped grips into which the ends of the specimen fit. The specimens have a “dog-bone” shape and are also manufactured by EDM.
Strain is measured directly on the specimen with laser-based interferometry from two tiny indentations placed in the specimen with a Vickers microhardness tester. Motion of the interference fringes emanating from the indentations is measured with two linear diode arrays and a microcomputer to enable real time strain measurement.
Preliminary tests have been conducted on brass samples to demonstrate the test technique. The relative uncertainty in stress measurement is high in these tests, but that arises from lack of precision in measuring the area. The relative uncertainty of strain is also high because of the crude mounts for the diodes. This paper demonstrates that the approach is feasible; straightforward refinements in the procedures will reduce the uncertainties.
Applications of Slow Strain Rate Testing in the Nuclear Power Industry
Authors: Miglin MT , Miglin BP 
Published: March 2009

Slow strain rate (SSR) tests are widely used to evaluate materials for service in the nuclear power industry. The slow strain rate method is used to select new materials and to qualify heats of existing materials for use in components exposed to reactor coolant.
Several different modifications of the SSR test have been developed over the years to meet the demands of specific reactor applications. For testing the nickel-base superalloys used in reactor core internals, tensile bars may be notched or fatigue-precracked to accelerate crack initiation. A precracked fracture mechanics specimen may be substituted for a tensile bar. Three-point-bend loading, rather than tensile loading, is used for evaluating material resistance to cracking during the intermediate temperatures associated with reactor heat-up and cool-down transients.
for testing thin-walled steam generator tubing, tube tensile specimens or single-ligament tensile bars are used. Rather than testing in a typical steam generator environment, a high-temperature caustic environment may be chosen, with an anodic potential applied to the specimen to accelerate cracking.
The SSR test method is also applied to reactor pressure vessel steels and weldments. Tests conducted in reactor coolant environment have established the importance of maintaining low oxygen levels in preventing stress corrosion cracking (SCC).
Measurement of the Deformability of Austenitic Stainless Steels and Nickel-Base Alloys in Light Water Reactor Cores
Authors: Dewes P , Alter D , Garzarolli F , Hahn R , Nelson JL 
Published: March 2009

The deformability of austenitic stainless steels and nickel-base alloys was studied in an experimental program combining the influence of irradiation in a light water reactor (LWR) core environment and high stresses and strains. Tubular specimens filled with ceramic mandrels were inserted into fuel elements of both a BWR and a PWR where they were exposed to the neutron flux and coolant water of the core. The ceramic mandrels swelled under irradiation and applied high stresses to the cladding tube specimens; hence, in case of sensitive material, this led to intergranular stress corrosion cracking. The strain was varied by choosing different ceramic materials and by the axial position of the specimens in the reactor core. During the refueling shutdown of the reactor, the specimens were examined by integrity testing and diameter measurements.
The experimental setup, irradiation conditions, examination methods, and deduced stresses will be described and the status of the experiments outlined. Many materials failed by brittle cracking under the conditions applied. In the first program phase only a low phosphorus and silicon stainless steel and an Inconel alloy 718 with a special heat treatment were found to be resistant. In the second phase, when other material charges were used to verify the first results, the good performance of alloy 718 was confirmed. High purity austenitic stainless steels, however, failed during Phase 2 at the same low strain level as commercial purity material. In the case of alloy X-750, it was found that the material surface condition had a significant influence on the resistance to stress corrosion cracking.
Slow Strain Rate Fracture of High-Strength Steel at Controlled Electrochemical Potentials in Ammonium Chloride, Potassium Chloride, and Ammonium Nitrate Solutions
Authors: Nguyen DT , Nichols DE , Daniels RD 
Published: March 2009

Earlier investigations using slow strain rate fracture tests at controlled electrochemical potentials demonstrated the susceptibility of AISI 4340 high-strength steel to stress corrosion cracking (SCC) in the combustion product residues of jet engine cartridge ignition starters. X-ray diffraction analyses of the residues revealed significant concentrations of ammonium chloride, potassium chloride, and ammonium nitrate. In the present investigation, slow strain rate testing was conducted to determine the effects of each of these chemical compounds on the fracture process. Test environments included ammonium chloride, potassium chloride, and ammonium nitrate solutions at concentrations of 100, 1000, and 10 000 parts per million by weight and at a pH of 5. The tests were performed at a constant extension rate of 1 × 10-7 m/s (strain rate of approximately 2.7 × 10-6/s). Tests were performed at controlled electrochemical potentials, both anodic and cathodic with respect to the open-circuit corrosion potential, to delineate the potential ranges for SCC and hydrogen-induced cracking.
Of the three compounds studied, only ammonium chloride caused SCC of the AISI 4340 high-strength steel. The corrosion potential of about -620 mV versus saturated calomel electrode (SCE) is at the brink of the potential range for stress corrosion cracking. The most severe embrittlement was observed at a potential of -450 mV and at a solution concentration of 1000 ppm ammonium chloride. Hydrogen-induced cracking was observed at -850 mV in the ammonium chloride and ammonium nitrate solutions, but not in the potassium chloride solutions.
Hydrogen Cracking Initiation of a High-Strength Steel Weldment
Authors: Klein PA , Hays RA , Moran PJ , Scully JR 
Published: March 2009

The hydrogen assisted crack initiation susceptibility of 5-Ni-Cr-Mo-V (MIL-S-24371A) quenched and tempered steel plate, weldment, and Gleeble thermal cycled materials representative of tempered and untempered weld metal was investigated in 3.5% NaCl solution. The conjoint role of steady state diffusible hydrogen content and maximum principal stress was quantitatively characterized by: (1) Devanathan-Stachurski hydrogen permeation tests, and (2) slow strain rate tests conducted under various cathodic protection levels.
For the four material conditions studied, the threshold maximum principal stress decreased with increasing hydrogen concentration. The base plate was less susceptible to hydrogen assisted crack initiation than the weld metal and thermal cycled weld metals. The tempered and untempered thermal cycled weld materials defined the upper and lower bounds of the aswelded material cracking susceptibility respectively.
Relationship of Localized Corrosion and SCC in Oil and Gas Production Environments
Authors: Wilhelm SM , Currie DM 
Published: March 2009

Laboratory corrosion tests consisting of electrochemical cyclic polarization, critical pitting temperature (CPT), and slow strain rate (SSR) tests were performed on a group of candidate nickel base alloys. The objective of the test program was to predict service performance in deep sour gas well applications. Of particular interest were localized corrosion resistance and stress corrosion cracking (SCC).
The test data indicated that localized corrosion can occur at intermediate temperatures (110 to 170°C) and that SCC may also occur in this temperature region. The temperature region of susceptibility coincides with the transition from a stable chromium oxide surface film to a predominantly sulfide surface film. The localized loss of chromium oxide protectiveness at 150 to 180°C is manifested by crevice corrosion, pitting, and ductility loss. Elemental sulfur in the test environment lowers the region of susceptibility to 100 to 150°C.
From the information provided by this experimental program (and others), procedures and criteria were established for purchase specifications for tubular products. SSR test methods were used to predict service performance.
Elevated Temperature Behavior of Sintered Silicon Nitride Under Pure Tension, Creep, and Fatigue
Authors: Sankar J , Krishnaraj S , Vaidyanathan R , Kelkar AD 
Published: March 2009

Pure tensile fast fracture, tensile creep, and tensile cyclic fatigue/creep interaction data are reported for GTE SNW-1000 sintered silicon nitride (Si3N4) which is being investigated as a candidate material for advanced heat engine applications.
Pure uniaxial tensile tests conducted at room temperature and at elevated temperatures indicate that the tensile strength of this material was retained to 1100°C, above which there was a sharp decrease in strength.
Tensile creep tests performed at 1100°C and 1200°C showed that the steady state creep rate was dependent on both the temperature and the applied stress, the effect of temperature being more dominant than the applied stress. Further, creep induced deformation by linking of small pores, and changes in the chemical contents were observed.
The effect of cyclic loading on creep, and residual tensile strength were also studied at 1200°C. Test results showed that precycling can dramatically increase creep resistance. Cyclic loading at 1200°C also increases the strength of the material.
The Multiaxial Equivalent of Stressed Volume
Authors: Tucker WT , Johnson CA 
Published: March 2009

A comprehensive probabilistic fracture analysis methodology should allow data to be combined or pooled from multiple specimen sizes and geometries such that all available fracture data can be integrated into strength/probability estimates and such that size-scaling aspects of the model can be tested. Moreover, this capability must, among other things, allow for multiaxial stress states, and be be capable of providing a measure of the statistical uncertainty in estimates of strength and/or probability including confidence and tolerance bounds. Previous efforts of the authors have produced estimators for combined data, confidence and tolerance bounds on estimates, bias and bias correction of estimates and measures of statistical efficiency of the estimators. These developments have been based on Weibull's uniaxial model involving k, a dimensionless “load factor” or “structure factor.”
The results presented in this paper show that similar techniques are applicable to more comprehensive models of multiaxial failure. Building on previous work by the first author, reported elsewhere, and generalizing results recently reported in the literature, it is shown that the Batdorf-Heinisch's (B-H) flaw density distribution and the Lamon-Evans' (L-E) elemental strength approaches to weakest-link fracture statistics for multiaxial loading give equivalent probability predictions for equivalent failure criteria. A generalization is also given detailing necessary and sufficient conditions for the B-H and L-E approaches to be equivalent. This allows a general size factor to be defined that simultaneously takes into account geometry, loading, and multiaxial stresses. This general size factor replaces k in the estimators for combined data, confidence and tolerance bounds on estimates, bias and bias correction of estimates and measures of statistical efficiency previously developed by the authors. It can be applied on an elemental basis or to a component structure as a whole, and this has consequences in determining probability predictions. Also employing these results, it is indicated how a contradictory conclusion, also reported in the literature, was reached. All in all, there appear to be no obvious roadblocks in incorporating the effects of multiaxial stresses into current analysis methods. Moreover, the form of the generai size factor indicates that it may be possible to obtain generalizations that cover time and/or temperature effects. Thus, the equivalence of the B-H and L-E formulations has broad reaching implications.
Annual Survey of Catastrophic Football Injuries: 1977–1992
Authors: Mueller FO , Cantu RC 
Published: March 2009

Football catastrophic injuries may never be totally eliminated, but continued research has resulted in rule changes, equipment standards, improved medical care both on and off the playing field, and changes in teaching the fundamental techniques of the game. These changes were the results of a united effort by coaches, administrators, researchers, equipment manufacturers, physicians, trainers and players.
Research based on reliable data is essential if progress is to be made. Research provides data that indicate the problems and reveal the adequacy of preventive measures.
The Effect of Temperature and Humidity on the Fatigue Behaviour of Composite Bonded Joints
Authors: Gilmore RB , Shaw SJ 
Published: March 2009

Simulated aircraft structural joints using CFRP adherends and a supported (for bond thickness control) and an unsupported version of a 120°C epoxy adhesive were fatigued at five different combinations of temperature and humidity. These combinations were: ambient dry, and at 85%RH, 90°C dry, and at 65%RH, and -50°C. The high humidity fatiguing made use of a saturated salt humidity chamber specially developed for the purpose.
The joint geometry used was a variation of a cracked-lap shear joint chosen because it simulated actual joints, allowed the progress of fatigue damage to be observed, and was simple to manufacture.
Fatigue damage was monitored and assessed via a combination of microscopy, ultrasonic inspection and radiography.
The results obtained showed that the fatigue behaviour of adhesive joints was considerably affected by temperature, humidity, and support medium. Cohesive failure of adhesive, interfacial failure, and interlaminar failure of adherends were all observed, such that predictions of structural integrity would be difficult to make. In addition, failure modes observed could be aggravated by, or themselves exaggerate, gross defects or inconsistencies already present in a structure, e.g. impact damage. Optimum static performance may not give acceptable fatigue behaviour.
Simulation of Microbiologically and Chemically Influenced Corrosion of Natural Sandstone
Authors: Mansch R , Bock E 
Published: March 2009

A test system for the simulation of a combined chemically (gaseous pollutants) and microbiologically (nitrifying bacteria) influenced corrosion on natural sandstone is presented. A high stone moisture was essential for the growth of nitrifying bacteria on test stones. Under optimum conditions, a nitrifying biofilm developed on the calcareous Ihrlersteiner green sandstone, reducing the evaporation from the stone surface. Biofilm cells adapted well to high concentrations of gaseous pollutants.
The mean metabolic activities of ammonia oxidizers were 11 and those of nitrite oxidizers 30 times higher than mean values of samples from historical buildings.
The microbiologically influenced nitric acid corrosion alone was stronger than the chemically influenced corrosion by a smog atmosphere (1065-μg/m3 sulphur dioxide, 850-μg/m3 nitric oxide, and about 450-μg/m3 nitrogen dioxide). While 72 μmol of calcium were solubilized per week of exposure to the smog atmosphere, 161 μmol of calcium per week were solubilized by the nitric acid produced by nitrifying bacteria.
If gaseous pollutants were added, the microbiologically produced nitrite and nitrate were removed by the action of sulphur dioxide. Thus, the combined attack of nitrifying bacteria and gaseous pollutants did not result in increased corrosion.
Accelerated Biogenic Sulfuric-Acid Corrosion Test for Evaluating the Performance of Calcium-Aluminate Based Concrete in Sewage Applications
Authors: Sand W , Dumas T , Marcdargent S 
Published: March 2009

The corrosion of concrete structures in sewage environments is a major problem in some areas. The phenomena leading to formation and stripping of H2S are now reasonably well understood. By a biologically-influenced process, the metabolism of thiobacilli, hydrogen sulfide is converted into sulfuric acid. This acid reacts with concrete and causes deterioration.
For the purpose of testing materials, this environment is often simulated by laboratory tests with concentrated acid solutions. Such tests, however, do not consider the bacterial aspect of the reality, and therefore, can lead to irrelevant conclusions.
For a reliable result, the interactions between living organisms and their substratum are essential and need to be taken into account. This task is achieved by the use of our simulation chamber for biogenic sulfuric-acid corrosion. The biologically-influenced corrosion is remodeled under conditions favoring the relevant microorganisms. Thus, an acceleration of the natural process is achieved.
Recent investigations conducted on calcium-aluminate-based mortars in the bacterial-corrosion chamber of Hamburg University demonstrated for these materials a good resistance against biogenic sulfuric-acid attack. These results are confirmed by on-site observations of sewer pipelines made of calcium-aluminate-based concrete inspected after up to 35 years of service in harsh environments.
Correlation of Field and Laboratory Microbiologically Influenced Corrosion (MIC) Data for a Copper Potable Water Installation
Authors: Wagner DHJ , Fischer WR , Paradies HH 
Published: March 2009

A copper-corrosion process of unknown origin was observed in the cold and warm water supplies shortly after commissioning a county hospital in Germany. The cause of the damage could be attributed to microbial-influenced corrosion (MIC). An evaluation of the damage showed that corrosion is most likely to occur in intensively branched, horizontal pipework during prolonged periods of stagnation. The influences of operating conditions and design installation on the corrosion process could not be separated.
The operating conditions and design installation can be separated in test rigs using the occurrence manifestation characteristics for this corrosion process as a measure for the likelihood of corrosion. After an induction period of 200 days the corrosion is most often found under intermittent and stagnant conditions in the test rigs. Furthermore, a seasonal influence can be observed. It was shown in experiments performed in the laboratory that it should be possible to considerably minimize this induction period found in the test rigs.
An Evaluation of Countermeasures to Microbiologically Influenced Corrosion (MIC) in Copper Potable Water Supplies
Authors: Fischer WR , Wagner DHJ , Paradies HH 
Published: March 2009

Unexpected pitting of copper pipes in drinking water installations has appeared mainly in public buildings (often in hospitals) at a small number of places around the world (for example, Germany, Scotland, Saudi-Arabia). Experience and scientific based knowledge about pitting corrosion of copper does not indicate a remarkable susceptibility in the respective drinking water installations. Because substances of biological origin were mixed with the solid corrosion products, the following hypothesis was generally accepted: microbiologically influenced corrosion (MIC).
Though the mechanism of MIC is by no means clear in detail, promising countermeasures have to be developed, substantiated and introduced into practice to protect existing installations. In this paper, the arguments for qualified actions are described and, when available, the success of these measures are mentioned. It can be stated that the likelihood of MIC in copper can be reduced to technically acceptable or even to negligible values by a combination of some well-known methods of corrosion protection.