bluuebunny/crossref_metadata_2025 huggingface dataset:
Irradiation Response of the IAEA CRP-3 Material FFA Measured by Fracture Toughness Specimens
Authors: Valo M , Wallin K , Törrönen K , Ahlstrand R
Published: March 2009

The irradiation response of the French forging material FFA offered by International Atomic Energy Agency (IAEA) has been measured. Charpy-V and precracked specimens of three-point bending (3-PB) geometry for J-Δa curve measurement have been irradiated in the surveillance position of the Loviisa nuclear power plant (NPP) in a flux of 2 × 1011 n/cm2s to a fluence of approximately 2.0 × 1019 n/cm2 E > 1 MeV, at a temperature of 265°C.

The irradiation-induced transition temperature shifts measured with Charpy-V and fracture toughness specimens are correlated by using indexed temperature values.

The shapes of the brittle fracture transition curves, measured with 3-PB specimen geometry, for irradiated and reference material states are compared using a statistical brittle fracture model. Both the shape of the average curve and the scatter of the measured points are considered.

The effect of irradiation on the ductile fracture behavior based on the measured fracture resistance curves (J-Δa) is presented. The 3-PB specimen geometry is used also for measuring the fracture resistance curves.
Influence of Phosphorus on Thermal and Neutron Embrittlement of Pressure Vessel Steels
Authors: Soulat PE , Miannay D , Horowitz H
Published: March 2009

In conjunction with an international study coordinated by the International Atomic Energy Agency (IAEA), a review was made of three Japanese model steels with different phosphorus and copper contents irradiated at 5.1019 n ∙ cm-2 (E > 1 MeV) to explain the influence of phosphorus on the thermal and neutron embrittlement of steels.

The results obtained show an important phosphorus effect on radiation hardening and embrittlement in the low-copper steels, an appreciable embrittlement after thermal segregation of phosphorus due to a change in fracture mode from cleavage to intergranular, and a radiation hardening and embrittlement of the same order of magnitude on the segregated steel for irradiation effect.
Irradiation and Annealing Behavior of 15Kh2MFA Reactor Pressure Vessel Steel
Authors: Popp K , Bergmann U , Bergner F , Hampe E , Leonhardt W-D , Schützler H-P , Viehrig H-W
Published: March 2009

This work deals with the mechanical properties of reactor pressure vessel (RPV) steels used in the pressurized water reactors (PWR) of former Soviet type WWER-440. The materials under investigation were a forging (base metal 15Kh2MFA) and the corresponding weld. Charpy V-notch specimens and tensile test specimens were irradiated in the PWR WWER-2 Rheinsberg at about 270°C up to the two neutron fluence levels of 4 × 1018 and 5 × 1019 n/cm2 (E > 1 MeV). Post irradiation annealing heat treatments were performed, among others a 475°C/152 h treatment of technical interest.

A set of experimental data is given regarding the influence of sampling depth (through thickness position within the forging), neutron irradiation, and annealing on the properties derived from instrumented Charpy impact testing, tensile and hardness tests. The ferrite content varies through the thickness of the forging. The variation of the mechanical properties can be explained qualitatively with the varying ferrite content. The surface layer of the forging is more sensitive to neutron irradiation than material from the 1/4-T position.

To evaluate the effect of annealing heat treatment, the kinetics of the recovery process for the hardness has been investigated. The recovery coefficients for different mechanical properties and parameters have been compared. The annealing behavior is too complex to predict the effect of a large-scale annealing of an RPV on the basis of single hardness measurements.
Thermal Annealing of the Reactor Pressure Vessel NPP Unit 2 in Jaslovské Bohunice for Its Radiation Embrittlement Regeneration
Authors: Kupča Ĺ , Čepček Š
Published: March 2009

The status of the preparation works tor the thermal annealing operation at reactor pressure vessel (RPV) V-230-type Unit 2 in Jaslovské Bohunice planned for Autumn 1993 is presented in this paper. The producer of the RPV W-213 type. ŠKODA Works, will perform the thermal annealing operation and manufacture all equipment needed. During the planned shutdown for the refueling operation of this unit in September 1989, samples were prepared from base material (BM) and weld metal (WM) by means of special equipment used for the analysis of the chemical composition in the Nuclear Power Plants Research Institute (VÚJE) laboratories. Results of the analysis of the irradiated samples and the hardness measurements of RPV material before and after annealing operation serve as the measure of radiation embrittlement recovery efficiency. Possible extension of the operation life of RPVs of WWER type by means of suitable provisions during normal operation before thermal annealing is also discussed.
Multiaxial Stress-Strain Modeling and Fatigue Life Prediction of SAE Axle Shafts
Authors: Chu C-C , Conle FA , Bonnen JJF
Published: March 2009

A three-dimensional stress-strain model with an isotropic-kinematic hardening rule has been successfully applied to obtain estimated stress histories from the rosette strain histories. The strains are measured on surface elements near the notch root of SAE axle shafts subjected to variable-amplitude multiaxial service loading conditions. The critical plane approach is adopted to predict fatigue lives by examining the detailed stress and strain states on all potential critical planes of an element. Several commonly used damage criteria as well as a work-based criterion proposed here are evaluated by comparing the predicted and experimentally observed fatigue lives for a wide range of tests. The encouraging results demonstrate the current model's capability of simulating complex tests and predicting fatigue lives.
In-Phase and Out-of-Phase Axial-Torsional Fatigue Behavior of Haynes 188 Superalloy at 760°C
Authors: Kalluri S , Bonacuse PJ
Published: March 2009

Isothermal, in-phase and out-of-phase axial-torsional fatigue experiments have been conducted at 760°C on uniform gage section, thin-walled tubular specimens of a wrought cobalt-base superalloy, Haynes 188. Test control and data acquisition were accomplished with a minicomputer. Fatigue lives of the in- and out-of-phase axial-torsional fatigue tests have been estimated with four different multiaxial fatigue life prediction models, a majority of which were developed primarily for predicting axial-torsional fatigue lives at room temperature. The models investigated were: (1) the von Mises equivalent strain range, (2) the modified multiaxiality factor approach, (3) the modified Smith-Watson-Topper parameter, and (4) the critical shear plane method of Fatemi, Socie, and Kurath. In general, life predictions by the von Mises equivalent strain range model were within a factor of 2 for a majority of the tests, and the predictions by the modified multiaxiality factor approach were within a factor of 2, while predictions of the modified Smith-Watson-Topper parameter and of the critical shear plane method of Fatemi, Socie, and Kurath were unconservative and conservative, respectively, by up to factors of 4. In some of the specimens tested under combined axial-torsional loading conditions, fatigue cracks initiated near extensometer indentations. Two design modifications have been proposed to the thin-walled tubular specimen to overcome this problem.
Effects of Material Anisotropy on Cyclic Deformation and Biaxial Fatigue Behavior of Al-6061-T6
Authors: Lin H , Nayeb-Hashemi H
Published: March 2009

Anisotropic cyclic stress-strain curves (CSSCs) and fatigue lives were obtained from fully reversed fatigue tests in strain control on two orientations of an Al-6061-T6 plate (along the rolling direction and the transverse direction). The experiments were conducted at room temperature in air under three loading conditions: tension/compression, torsion, and combined tension/torsion in-phase. Based on the CSSCs data, the anisotropic constitutive relations of the material were obtained by using Hill's anisotropic plasticity theory. Yield loci and flow behavior were determined and compared to theoretical predictions. Two anisotropic effective stress-effective strain criteria were evaluated. During the fatigue tests, fatigue cracking behavior was observed. The damage mechanism of the material was shear dominated. Four multiaxial fatigue life prediction models representing three different concepts were used to correlate the anisotropic fatigue life data of the plate under the biaxial loadings. A new shear cracking model incorporated with material anisotropy coefficients is proposed and correlated with the fatigue life data very well.
Thermomechanical Loading in Pure Torsion: Test Control and Deformation Behavior
Authors: Bakis CE , Castelli MG , Ellis JR
Published: March 2009

An investigation of thermomechanical testing and deformation ehavior of tubular specimens under torsional loading is described. Experimental issues concerning test accuracy and control specific to thermomechanical loadings under a torsional regime are discussed. A series of shear strain-controlled tests involving the nickel-base superalloy Hastelloy X were performed with various temperature excursions and compared to similar thermomechanical uniaxial tests. The concept and use of second invariants of the deviatoric stress and strain tensors as a means of comparing uniaxial and torsional deformations is presented and critiqued for its applicability to the present data. The hardening behavior of the torsional specimens is also briefly presented and discussed in light of previous thermomechanical tests conducted under uniaxial conditions.
Inelastic Stress-Strain Predictions for Multiaxial Fatigue Damage Evaluation
Authors: Tipton SM , Bannantine JA
Published: March 2009

The inelastic stress-strain response of a material subjected to complex loading must be known or estimated in order to predict the fatigue life of a component using many current multiaxial fatigue damage models. This paper presents stress-strain predictions obtained using two incremental plasticity algorithms for several nonproportional loading paths.

The two algorithms both employ von Mises yield surfaces with kinematic hardening. However, one algorithm translates a single yield surface within a stationary limit surface using the hardening rules specified by Mróz and invokes a radial return for neutral loading. The other algorithm translates multiple yield surfaces (or a field of plastic moduli) according to a modified Mróz hardening rule proposed by Garud with no neutral loading provision. The algorithms are used to predict stress histories that are compared with measured responses from strain-controlled tests on normalized 1045 thin-walled tubes. A variety of nonproportional load paths were investigated. In general, relatively good agreement between predicted and measured stress-strain response for the two algorithms was observed for application to multiaxial fatigue evaluation. Strengths and weaknesses of each model are discussed.
Propagation Behavior of Small Cracks in 304 Stainless Steel Under Biaxial Low-Cycle Fatigue at Elevated Temperature
Authors: Ogata T , Nitta A , Blass JJ
Published: March 2009

To investigate the initiation and propagation behavior of small cracks and the relationship between crack propagation and fatigue life, strain-controlled in-phase and 90° out-of-phase axial-torsional fatigue tests were conducted at 550°C, using tubular specimens of 304 stainless steel with and without surface notches. Each test was interrupted at frequent intervals to make a film replica of the outer surface of the specimen for examination with an optical microscope. Most of the fatigue life was spent in the propagation of small cracks less than 2 mm long. Regardless of loading conditions, the crack propagation rate correlated well with the equivalent shear strain range defined as a function of shear strain range and normal strain range on the plane of maximum shear strain range. The biaxial low-cycle fatigue life could be estimated from the relationship between the crack propagation rate and the equivalent shear strain range.
Damage Observation of a Low-Carbon Steel Under Tension-Torsion Low-Cycle Fatigue
Authors: Bérard JY , McDowell DL , Antolovich SD
Published: March 2009

Low-cycle fatigue tension-torsion tests were performed on a low-carbon steel. The formation of microcracks as a function of orientation and state of stress was studied. Quantitative measurements of microcrack density and length showed that microcracking occurred in the maximum shear direction for various stress states. Transgranular microcracks were mostly observed. An increasing amount of intergranular microcracks was observed for out-of-phase tension-torsion loading. A shear-based microcrack propagation approach incorporating a normal stress effect was shown to provide a better correlation of the damage distribution of a pure torsion test.
Mixed Mode Fatigue Crack Growth Behavior in a High-Strength Steel
Authors: Link RE
Published: March 2009

Most of the currently available methods for predicting fatigue crack growth in structures do not consider effects due to mixed-mode loading. This is partly due to the limited information available concerning the fatigue crack growth under mixed mode loading. Previous investigations of mixed mode effects on fatigue crack growth have shown that under combined opening and in-plane shear loading, the cracks turn abruptly so that the in-plane shear mode is eliminated [1–3]. Very little data are generated before the crack curvature eliminates the mixed mode loading. The changing orientation of the crack during the test makes analysis of the problem difficult and may cloud the intrinsic fatigue crack growth rate behavior under mixed mode loading. Situations can exist in engineering structures in which cracks may grow in a self-similar manner even under the influence of mixed mode loading. Examples of such situations are radial cracks in bearing races [4] and transverse cracks in rotating shafts under shear and bending loads. The cracks may not change orientation because the in-plane shear component is fully reversed. It is necessary to understand the effects of mixed mode loading on fatigue crack growth in order to properly predict the behavior of these components.

This paper presents the results of an investigation to measure the fatigue crack growth rate of a high-strength steel under various ratios of mixed mode loading while maintaining self-similar crack growth. A primary objective of this investigation was to generate data for relatively large amounts of crack growth under a wide range of mixed mode ratios. Several models for predicting the mixed mode fatigue crack growth rate from opening mode data are evaluated based on the data generated in this investigation.
Crack Curvature in Thin Cylinder Failure
Authors: Fyfe IM , Guo ZH , Guo ZK
Published: March 2009

An investigation was conducted on the role played by different factors on the directional stability of cracks in pressurized thin-walled cylinders under fatigue loading conditions. In addition to internal cyclic pressure, the test system was designed to allow axial loads to be applied independently. Fractional factorial design techniques were used to determine the interaction between a number of different parameters which could possibly control the crack path direction.

This statistical analysis shows the importance of the key experimental parameters and the interaction of these parameters on the crack path. It also serves to show that, although crack length and pressure control the bulge characteristics, a symmetric bulge in itself only plays a part in determining the stability of the crack path but not the direction. Another aspect of the study was examining the possible mechanisms which control the direction taken by an inherently unstable crack and the effect these mechanisms could have on the KII/KI ratio associated with the theoretical models of crack growth direction.
Application of a Multiaxial Load-Notch Strain Approximation Procedure to Autofrettage of Pressurized Components
Authors: Köttgen VB , Schön M , Seeger T
Published: March 2009

Theoretical approaches to predict the effect of autofrettage on the formation of residual stresses have been limited to tubes. This paper presents a new procedure to calculate approximately the residual stresses in pressurized components of any shape—with and without notches. The procedure developed can account very precisely for changes in the deformation behavior of metals during the first load cycles, e.g. the Bauschinger effect. An extension of the constitutive model of Mróz to cyclic hardening and softening was developed to verify the approximation with finite element analyses. Very good agreement between the results of both approaches was found. Through application of the procedure it was found that maximum residual stresses were usually generated by the pressure, producing a fully plastic net section. Only in a special case did the pressure, which gave maximum residual stresses, coincide with the lowest pressure, producing reversed yielding, which in the past often has been regarded as optimal pressure.
Notch Root Inelastic Strain Estimates Using GLOSS Analysis
Authors: Seshadri R , Kizhatil RK
Published: March 2009

Inelastic strains in notched mechanical components and structures can be predicted with reasonable accuracy using the generalized local stress strain (GLOSS) method of analysis. The GLOSS diagram is essentially a normalized stress-strain plot of a “local” region that is subjected to greater inelastic strains as compared to the “remaining” region. Inelastic response of the local region due to plasticity and creep is simulated by artificially lowering the stiffness of the nominally inelastic region. Thus, inelastic strains at the root of a notch can be estimated on the basis of two linear elastic finite element analyses per point on the load-notch strain curve.

The theory underlying GLOSS analysis essentially relates the inelastic multiaxial stress redistribution in the local region to the uniaxial stress relaxation process. The varying degrees of interaction between the local and remaining regions, which are characterized by the “constraint parameter,” enable the determination of inelastic strains when used in conjunction with the cyclic stress strain curve.

The GLOSS method of analysis can be used to estimate inelastic effects for realistic notch geometries and component loadings. The method can be applied in a routine manner to a range of inelastic zone sizes. The incorporation of an Irwin's type of correction to the plastic zone enables reasonably accurate determination of the inelastic notch strains for the purpose of low-cycle-fatigue evaluations. The GLOSS method is applied in this paper to several geometric configurations of practical interest.
CVD Multiple-Layer Coatings on 9Cr18 Steel and Its Application for High-Precision Ball Bearings
Authors: Chen HZ , Pen ZX , Lei JZ , Duan TH , Song XK , Fan YW
Published: March 2009

The process, microstructure and mechanical properties of the chemical vapor deposition (CVD) multiple-layer coatings titanium carbide, titanium carbonitride, and titanium nitride (TiC,TiCN,TiN) on 9Crl8 (1%°C, 18%°C) steel were investigated, and the process has been successfully applied to high-precision bearings. The results indicate that CVD multiple-layer coating has fine-grained microstructure and good adhesion, i.e., the bond strength to substrate. CVD multiple-layer-coated 9Crl8 steel has good properties of friction-wear resistance and high rolling contact fatigue life. The coating follows perfectly the substrate deformation at the compressive load testing, and its bearing load capacity depends on the strength of substrate. After CVD-coated 9Crl8 steel balls were lapped in batches, their surface roughness was noticeably improved. The performances of the high-precision bearings with CVD-coated balls increased significantly. After 1000 h operation, no trace of wear on the CVD-coated balls and uncoated bearing races was observed.
Work Hardening of Ball Surfaces
Authors: Schreiber E , Simon W , Zoch H-W
Published: March 2009

By cold-working the ball surface to a specific degree, it can be made less susceptible to being deformed during testing, transport, and assembly. This paper describes the cold working process and the effect of various process parameters on the resulting residual stress depth patterns. Life tests are described that were carried out with rolling bearings having balls of various cold-working levels. Damage analyses show that the fatigue strength of the ball surface can be reduced by excessive cold working.
The Development of Bearing Steels for Long Life Rolling Bearings Under Clean Lubrication and Contaminated Lubrication
Authors: Furumura K , Murakami Y , Abe T
Published: March 2009

Nearly ten years have passed since the LF-RH-CC process was adopted in the production of bearing steels. This process has become a common system for steelmakers, regardless of using EFs or BOFs as melting furnaces. The current cleanliness level of bearing steels shows a remarkable improvement when compared to that of ten years ago. The oxygen content in most steels has reached the high level of cleanliness of less than 10 ppm throughout the world. The bearing life in laboratory tests has been extended by several times in the last ten years.

However, in the fields of engineering and technology of bearing production and applications, it is still a matter of primary concern how to settle the problems of inside and outside debris— that is, how to grasp quantitatively and control accurately nonmetallic inclusions in steels and how to deal with outside debris that penetrates into the bearings exposed to application environments. This paper presents the latest results of studies relating to these timely problems.
Bearing Material/Treatment Developments at the SKF Engineering and Research Centre
Authors: Beswick J , Voskamp A , v. d. Sanden J , Verburgh M , Horton S
Published: March 2009

The Engineering and Research Centre of the SKF Group (SKF ERC) is involved in the development and evaluation of materials for bearings.

Physical metallurgy activities include advanced electron microscopy studies, in particular, relating microstructures to bearing functional properties. The microstructure is affected to a great extent by the composition, prior processing, and applied heat treatment and some of these relationships are described in the paper.

Fatigue investigations involve the definition of the fatigue process in bearing materials. The major discoveries on fatigue processes in steels, in recent years, have been made by the use of X-ray diffraction techniques. By the application of a “pole figure” measurement program it has been quantitatively established that significant texture develops during contact fatigue, resulting in the characteristic contact fatigue spall shapes related to the application conditions.

Ceramic powder processes are of interest for bearing products and silicon nitride has the best combination of mechanical and physical properties of the current engineering ceramics. At SKF ERC the necessary specifications and quality assurance procedures have been developed in order to select and approve specific types and grades of material for ceramic bearing manufacture.

Bearings are sometimes used in situations that are incompatible with the properties of the commonly used bearing steel grades. In such cases, coating processes may be used to tailor the surface properties of bearing components to specific application conditions. The development or evaluation, or both, of such processes takes place at SKF ERC which is equipped with various surface treatment facilities and test equipment for such coatings. Examples of coated bearing products are described in the paper.
Advances in the Production of Bearing Steels by Modern Secondary Metallurgy and Continuous Casting
Authors: Kremer K-J , Jung H-P , Peschke G , Rakoski F
Published: March 2009

Advanced production routes for billets, bars, and wire-rods for bearing application are discussed. The influence of modern secondary metallurgy, continuous casting, heating, rolling and heat-treatment on the critical product properties, especially non-metallic inclusions and microstructure, is presented.

Never-ending process improvement is the key to ensuring high consistency, reliability, and profitability.
Use of Rotary Continuous Cast Steel for Production of Tubes for Bearing Applications
Authors: Baudry G , Duplomb G , Giroud G , Saleil J , Jacob G
Published: March 2009

ASCOMETAL recently improved its steelmaking processes with the installation of new secondary metallurgy equipment (Ladle Furnace and RH degasser) and by the application of continuous casting to the production of bearing steels (AISI/SAE 52100). Such material, after rolling, is used by VALTI to produce seamless tubes for bearing producers. Thorough investigations were performed on such products including rolling contact fatigue tests. They showed that Rotary Continuous Cast (RCC) steels were at least equivalent to high-quality ingot materials, and that very high rolling contact fatigue properties can be achieved by proper and careful design of the overall process route, including continuous casting.
Oxygen Compatibility of Metals and Alloys
Authors: Lowrie R
Published: March 2009

The oxygen compatibility of metals and alloys is highly important because they constitute the major part of most oxygen systems. The recent development of semi-standard tests for metal specimens has greatly increased our understanding of the ignitability and combustibility of commonly used metals and alloys. The results of such testing are summarized and discussed for the major alloy groups.

The need for interaction among material choice, component and system design, and operational procedures to arrive at the most economical safe solution is stressed. Some possible ways for producing metals or alloys with decreased combustibility in oxygen are suggested.
Insidious Iatrogenic Oxygen-Enriched Atmospheres as a Cause of Surgical Fires
Authors: de Richemond AL , Bruley ME
Published: March 2009

During many surgeries, the risks of fire exist because heat sources (e.g., electrosurgical probes, lasers) are used close to fuels (e.g., tracheal tubes, body hair, surgical drapes) in oxygen-enriched atmospheres (OEA). When the OEA is recognized as a hazard, precautions are taken to reduce the risk, e.g., minimizing oxygen concentration prior to use of electrosurgery.

However, some actions of the surgical team can lead to one of two types of OEAs that are not readily recognized by, or apparent to, the surgical team as a hazard. One type involves entering a body cavity that contains an OEA, during tracheostomy for example.The other type has an OEA developing around the surgical site as can happen when a misplaced or leaking breathing circuit is under the surgical drapes. With regrettable frequency in these cases, a surgical fire results.

This paper discusses several cases of fire during surgery that involved insidious oxygen-enriched atmospheres. Recommendations to prevent and to deal with such fires are also presented.
Effect of Hydrocarbon Oil Contamination on the Ignition and Combustion Properties of PTFE Tape in Oxygen
Authors: Shelley RM , Janoff DD , Pedley MD
Published: March 2009

Testing was conducted to determine and compare the sensitivities of two oxygen test methods for detecting the presence of hydrocarbon oil contamination on polytetrafluorethylene tape. Ambient pressure mechanical impact tests were conducted, using ASTM Test Method for Compatibility of Materials with Liquid Oxygen (Impact Sensitivity Threshold and Pass-Fail Techniques) (ASTM D 2512); the tests determined the effect of contaminant concentration on the minimum impact energy for ignition. In the other test method, developed at the NASA Johnson Space Center White Sands Test Facility, the contaminated tape was heated using a pyrolysis furnace in flowing, gaseous oxygen. The presence of hydrocarbons in the gaseous oxygen stream was detected by fourier transform infrared spectroscopy (FTIR). This test method also determined the autoignition temperature of the contaminated tape. The test results showed that FTIR of the gases from the pyrolysis furnace is significantly more sensitive than liquid oxygen mechanical impact tests for detecting the presence of contamination. However, the autoignition temperature determined in the pyrolysis furnace is far less sensitive to the presence of hydrocarbon oil contaminants than liquid oxygen mechanical impact tests. Additional testing was conducted using a modified pneumatic impact test system (ASTM Test Method for Ignition Sensitivity to Materials to Gaseous Fluid Impact [ASTM G 74]), to study the effect of hydrocarbon contamination on the ignition process.
Promoted Ignition-Combustion behavior of Carbon Steel in Oxygen Gas Mixtures
Authors: Mcllroy K , Million J , Zawierucha R
Published: March 2009

Promoted ignition-combustion is a term which has been used to describe a situation where a substance with poor oxygen compatibility ignites and supports the combustion of a more resistant material. Previous papers on the subject in recent years have reported on the investigation of this phenomenon as it related to carbon steel, stainless steels and a number of engineering alloys. However, the bulk of these investigations have involved relatively high pressures.

Carbon steel is a common alloy used in the construction of equipment used in industrial gas applications. Yet, promoted ignition-combustion test data on carbon steel samples showing the effects of variables such as test pressure, oxygen purity, temperatures, section size, promoter types, etc. on promoted ignition-combustion behavior are scarce; particularly, at low pressures.

In this investigation, the promoted-ignition combustion behavior of carbon steel was studied in oxygen-nitrogen gas mixtures over the pressure range of 0.118 MPa to 0.446 MPa with oxygen purities ranging from 70% to 99.7%. Comparative tests were made using 3.175 mm and 6.35 mm diameter rods at pressures up to 0.273 MPa. Over the pressure and purity ranges tested, there was little difference due to size effects. Carbon steel burns occurred at pressures as low as 0.118 MPa with oxygen purities of 95% and above, in the promoted ignition-combustion tests.
Pressurized Flammability Limits of selected Sintered Filter Materials in High-Pressure Gaseous Oxygen
Authors: Schadler JL , Stoltzfus JM
Published: March 2009

Previous promoted combustion tests have demonstrated that the threshold pressure (the minimum oxygen pressure required to self-sustain combustion) of various engineering alloys is dependent on the configuration of the sample. Monel 400, when configured as a 3.2-mm (0.13-in.) -diameter rod, has a threshold pressu re 500 times greater than when configured as a 60 × 60 wire mesh constructed of 0.19-mm (0.0075-in.) -diameter wire. Sintered filter elements, often used in oxygen systems, have finely divided construction (a high surface to volume ratio) similar to a wire mesh configuration. This similarity raises the question whether the threshold pressure data for the 3.2-mm (0.13-in.) -diameter rod, the wire mesh, or neither should be used for various alloys configured as sintered filter elements.

This study was conducted on three engineering alloys configured similar to sintered filter elements. Monel 400 powder, 316L stainless steel (SS316L) powder, and three types of tin-bronze powder were sintered into rods ranging in diameter from 3.2 to 6.3 mm (0.13 to .25 in.), with pore sizes representative of 3- to 150-μm-rated filters. Each sample was mounted vertically in a 12.4 liter (757 in.3) vessel and ignited at the bottom using an aluminum-palladium igniter wire. For each sample a threshold pressure was determined.

The test results indicated that the sintered Monel 400 and the sintered SS316L have threshold pressures closer to the wire mesh than 3.2-mm (0.13-in.) -diameter solid rods. As tested, the Monel had a threshold pressure of 0.69 MPa (100 psig) and the SS316L had a threshold pressure of White Sands Test Facility ambient, 82 kPa (12 psia). Except for two grades of A type sintered tin-bronze, all the sintered tinbronzes had threshold pressures above 68.9 MPa (10000 psig). Grade 153A and grade 103A had threshold pressures of 68.9 MPa (10000 psig) and 37.9 MPa (5500 psig), respectively. The results indicate that P or HP types of sintered tin-bronze filter elements are preferred for use in oxygen systems.
Review of Frictional Heating Test Results in Oxygen-Enriched Environments
Authors: Gunaji MV , Stoltzfus JM
Published: March 2009

Friction is a known ignition source for metals and polymers in oxygen systems. This paper provides a review of the test results currently in the literature and an update of frictional ignition tests recently conducted at WSTF. Most of the results are presented in terms of the Pv product required for ignition (Pvign), where P is the normal load divided by the rubbing area and v is the relative linear velocity between the samples. Rankings based on Pvign are presented for similar and dissimilar pairs of metal alloy test samples. A comparison of the Pvign in liquid oxygen (LOX) and the PVign in gaseous oxygen (GOX) indicates that materials are approximately three to four times more difficult to ignite in LOX than in GOX. A discussion of the application of the data to material selection is also presented.
Materials Selection for Sulfide Pressure Oxidation Autoclaves
Authors: Krag PW , Henson HR
Published: March 2009

Titanium and its alloys offer superior corrosion resistance in the oxidizing sulfuric acid environments present in sulfide pressure leaching operations. Their use is limited due to their pyrophoricity in high-pressure oxygen environments. We investigated the ignition resistance of several titanium alloys in oxygen using a tensile rupture technique. A commercial titanium alloy, niobium-55 wt. % titanium (Nb-55 Ti), was found not to ignite at pressure and temperature conditions under which Grade 2 titanium and other standard titanium alloys ignite. The decreased ignitability of titanium when alloyed with niobium is discussed in terms of a burn factor (the ratio of heat of oxidation to thermal diffusivity) and alloy microstructure. Nb-55 Ti, selected for its corrosion resistance, mechanical properties and reduced pyrophoricity compared to standard titanium alloys, has been successfully used in sulfide pressure oxidation equipment.
Modeling of Al And Mg Igniters Used in the Promoted Combustion of Metals and Alloys in High Pressure Oxygen
Authors: Steinberg TA , Wilson DB , Benz FJ
Published: March 2009

NASA determines flammability of metal and alloy samples in high pressure oxygen by Test 17 of NHB 8060.1C. An aluminum or magnesium promoter, releasing at least 3.0 kJ, is used as the sample ignition source. This ignition system is modelled using lumped-parameter mathematical equations and solved using the MATLAB computer code. Model parameters were obtained from the combustion of Al and Mg promoters on copper rods in the standard flammability instrument system. The copper rod is non-flammable under test conditions, that is, pure oxygen pressures of 3.44, 6.89, 20.7, 34.4 and 68.9 MPa. At test conditions, both aluminum and magnesium alloyed with the copper rod and burned in liquid phase reactions. The following heterogenous kinetic reaction rate functions were obtained: for Al: RAl=0.102Po21.+0.186Po2,g/m2s for Mg: RMg=0.067Po21.+0.146Po2,g/m2s.

The model is validated by comparing ‘time-to-ignition’ values for iron samples with measured experimental time-to-ignition for this material. Model predictions are between −5 to +28% of measured values. This work also provides ‘burn-rates’ for bulk aluminum and magnesium as functions of oxygen pressure.
Compatibility of Aluminum Packing with Oxygen Environments under Simulated Operating Conditions
Authors: Zawierucha R , Million JF , Cooper SL , McIlroy K , Martin JR
Published: March 2009

High surface area aluminum structured packings are possible components in cryogenic distillation columns used for air separation. Recently published literature has reported on the occurrence of strong energy releases involving aluminum structured packing which was subjected to flammability tests in the presence of liquid oxygen using strong thermite and magnesium promoters, under conditions which may not be typical of operating conditions in a cryogenic distillation column.

An experimental program was conducted to determine the compatibility of aluminum packing under test conditions which more closely simulated actual column operating conditions. The effects of various thermite, magnesium, hydrocarbon and metal promoters were evaluated in LOX/GOX environments with a nominal oxygen purity of 99.9% at pressures up to 0.17 MPa.

A major finding was that aluminum packing which was “irrigated” with LOX but not immersed in LOX did not experience severe energy releases in flammability tests up to a maximum pressure of 0.17 MPa at a nominal oxygen purity of 99.9 %. This simulated column operating conditions. Elimination of packing “irrigation” and immersion of the aluminum packing at one end in LOX resulted in a severe energy release in one test conducted at 0.16 MPa. The latter result verified recent literature reports but was not considered representative of packing operating conditions.

Of particular interest in this paper are details and schematics of a pressurized test vessel which was designed for the program. This test apparatus is capable of providing various combinations of packing immersion and irrigation, thereby simulating actual operating conditions.
Compatibility of Aluminium Packings with Oxygen — Test Results under Simulated Operating Conditions
Authors: Barthélémy HM
Published: March 2009

Metallic structured packings are used more and more in the cryogenic distillation of air because it results in systems that consume less energy than the conventional distillation tray technology employed before. These packings are normally manufactured from corrugated sheets of thin metal. Aluminium alloys are known to be the best candidate metal for these corrugated sheets because of their good properties at cryogenic temperatures excellent formability, light weight and low cost. The purpose of this investigation was to recheck the oxygen compatibility of aluminium structured packing under simulated operating conditions. First, a series of tests were performed using simplified testing conditions to identify the important parameters, such as oxygen purity, energy supplied (type and level), and oil contamination. These tests were carried out in gaseous, liquid and gaseous/liquid oxygen environments. A second series of tests was performed under simulated operating conditions, reproducing, in particular, the irrigation conditions found in normal service. These tests have confirmed the compatibility of aluminium packings with oxygen under actual operating conditions and confirmed the choice of this material for structured packing.
The Behaviour of Oil Films on Structured Packing Under Cryogenic Conditions
Authors: Kirzinger A , Baur K , Lassmann E
Published: March 2009

Today structured packing is commonly applied in cryogenic air separation plants. Packing is typically characterised by a high surface-to-volume-ratio. Due to the large surface of packing in comparison to common sieve trays — provided equal amounts of oil are attached to surfaces more organic material may be present within a low pressure column of an air separation plant. Since an enrichment of organic material in an air separation plant or in liquid oxygen is a principal hazard and a major accumulation of organic material magnifies this risk, experimental tests were conducted to determine whether chipping of oil at cryogenic temperatures is possible.

Tests are discussed where single sheets of a packing segment had been coated with an oil film of definite thickness. The oil coated sheets were rinsed by moving them up and down in liquid nitrogen or in liquid oxygen. After fixed time intervals the oil content of a single sheet was determined.

It was concluded that the original oil residue on the sheets up to 250 mg/m^ remained attached to the packing surface and no decrease of oil was found within the accuracy of the oil determination method.
A Critical Review of Flammability Data for Aluminum
Authors: Werley BL , Barthélémy H , Gates R , Slusser JW , Wilson KB , Zawierucha R
Published: March 2009

Aluminum is one of the more thoroughly studied metals for flammability properties. Results with aluminum in both the laboratory and the field have been mixed and experimentalists have obtained significantly differing data through the years, partly due to differing goals for application of the data. The literature contains data from ignition testing, propagation testing and heat of combustion testing. Ignition testing includes: autoignition temperature, liquid oxygen mechanical impact, friction, shock wave, resonance, promoter influence, fresh-metal exposure, and particle impact. Propagation testing includes: promoted combustion, propagation velocity, flammability limits, and alternative oxidants. Theory has been developed, but has not allowed prediction of aluminum's performance in specific applications.

Data and theory from more than one hundred sources and previously unpublished results of the contributing author's companies spanning the last forty years are abstracted and commentary is offered on experimental design, results and application to current-day loss prevention design of aluminum/oxygen systems.
Oxygen System Safety
Authors: Koch UH
Published: March 2009

This paper describes the hazards of high-pressure oxygen systems, lists five major causes of oxygen fires, and provides extensive references for additional information on the subject. The primary emphasis is on adiabatic compression, which has been identified as a significant but often overlooked cause of oxygen fires. The information contained in this paper was compiled from many sources; the author is not an oxygen safety expert or oxygen system design consultant. Oxygen users should obtain qualified professional assistance to establish design specifications and operating practices for the safe use of oxygen.
An Investigation of Laboratory Methods for Cleaning Typical Metallic Surfaces Using Aqueous Type Cleaning Agents
Authors: Mcllroy MS
Published: March 2009

Presently, industry places heavy reliance on the use of chlorinated solvents to achieve acceptable levels of cleanliness for systems in oxygen service. The Montreal Protocol and other restrictions will prohibit the use of these types of solvents because of potential damage to the environment. This paper discusses some of the issues involved in assessing aqueous based cleaning agents. A gravimetric test procedure has been developed to have a standard method of comparing the ability of a cleaning agent to remove oil and grease contaminants from prepared metal coupons. Data is presented to demonstrate the results of the test procedure. The testing addresses the use of a soak method and ultrasonics. The effects of time and temperature are directly addressed. Other variables are discussed in general terms such as disposal and cost considerations.

Three contaminants were selected for evaluation: hydrocarbon oil, lithium grease, and Halocarbon grease. Some of these contaminants present potential hazards in oxygen systems. The test method allows a common method for evaluation of cleaning agents and verification of contaminant levels for oxygen systems. The test procedures can also be applied to general degreasing of metal components throughout industry.
Deterministic Predictions of Corrosion Damage to High Level Nuclear Waste Canisters
Authors: Macdonald DD , Urquidi-Macdonald M , Lolcama J
Published: March 2009

The corrosion of titanium alloy canisters in a plutonic rock repository, as envisaged in the AECL/Ontario Hydro HLNW disposal concept, has been explored using four deterministic models. A Mixed Potential Model (MPM) was used to calculate the corrosion potential of the canister as a function of time after resaturation, and it is predicted that the corrosion potential will shift in the negative direction as the ambient oxygen is consumed coupled with a much smaller positive shift due to the decay in temperature. Maximum general corrosion rates have been estimated using the Maximum Rate Model (MRM) and the Radiolytic Maximum Rate Model (RMRM), both of which equate thecorrosion rate to the maximum possible flux of oxygen (MRM) and oxygen plus oxidizing radiolysis products (RMRM) to the canister surface. These calculations suggest that the radiolysis of water is not of major significance in establishing the general corrosion rate. Furthermore, general corrosion is predicted not to be a threat to the integrity of a thin wall (6.35mm) titanium container within the 500 year design life. Finally, corrosion rates have also been estimated using the WAPPA code and the container is predicted to withstand crevice corrosion for up to 1200 years and to be unbreached by general corrosion for 2000-2500 years after resaturation.
Corrosion Aspects of Copper in a Crystalline Bedrock Environment - with Regard to Life Prediction of a Container in a Nuclear Waste Repository
Authors: Sjöblom R
Published: March 2009

A disposal system for high-level and long-lived radioactive waste should provide for adequate isolation of radionuclides from the bio-sphere.

During the work of finding such a system, and in demonstrating its long-term isolation, certain unprecedented requirements become apparent: the disposal system must function over very long times without any need for maintenance or repair. Furthermore, no experience from operation can be made available for the analysis, and there will be no results from tests with durations comparable in magnitude to the life-time of the facility.

In the systems studied in Sweden and Finland, copper containers are deposited in crystalline bedrock with bentonite as a backfill. The groundwater is reducing and the flow is very low due to the low permeability of the bentonite clay and of the rock near the deposition hole.

The chemical durability of a container in such a disposal system will depend primarily on three factors: the mechanical tensile stresses in the container, the chemical environment, and the copper material itself. The tensile stresses depend on manufacturing factors as well as external forces. The chemical environment will depend on the composition of the groundwater, theibentonite clay and possibly also phenomena that might take place in the vicinity of the container. The copper material can corrode primarily by oxidation or sulphidation. If the salt concentration is high (and a reducible specie is available), copper may also react by forming chloride complexes.

If the copper container has thick walls, penetration by general corrosion will take considerable time. It is nevertheless of interest to study general corrosion since - at least under certain conditions - it will give rise to a protective and passivating surface layer. Such a layer may be of significance when the possibilities of localized corrosion and stress corrosion cracking are to be evaluated. It is pointed out that the development of localized corrosion is strongly dependent on the specific chemistry. Concern is expressed regarding certain treacherous aspects of stress corrosion cracking. Areas of research that may be fertile to pursue have also been identified.

A point is made that the safety analyses and scenarios should include both probable and less probable developments. Examples are given of the latter type.

A suggestion is made that samples of the container and of container material be left in the repository to enable evaluation and thus to facilitate improvements that future generations might wish to make.