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Intergranular Corrosion of High-Purity Aluminum in Hydrochloric Acid 1: Effects of Heat Treatment, Iron Content, and Acid Composition

Description: Note presenting an investigation of the intergranular corrosion of high-purity aluminum in hydrochloric acid studied as a function of iron content, heat treatment, and acid composition under conditions where the rate of intergranular penetration was of the order of 1 millimeter per week.
Date: February 1955
Creator: Metzger, M. & Intrater, J.
Partner: UNT Libraries Government Documents Department

Intergranular Corrosion of High-Purity Aluminum in Hydrochloric Acid 2: Grain-Boundary Segregation of Impurity Atoms

Description: Note presenting a study of the strength of the tendency for segregation to the gain boundaries of substitutional solute atoms which differ substantially in size from those of the solvent in single-phase high-purity aluminum through observations on the intergranular corrosion in 20 percent hydrochloric acid.
Date: April 1955
Creator: Metzger, M. & Intrater, J.
Partner: UNT Libraries Government Documents Department

An Investigation of the Mechanism of IGA/SCC of Alloy 500 in Corrosion Accelerating Heated Crevice Environments. Technical progress report

Description: OAK-B135 An Investigation of the Mechanism of IGA/SCC of Alloy 500 in Corrosion Accelerating Heated Crevice Environments. Technical progress report Note: This report was submitted electronically even though Part II A indicates by ''PAPER''.
Date: March 1, 2000
Creator: Lumsden, Jesse
Partner: UNT Libraries Government Documents Department

Modeling of stress distributions on the microstructural level in Alloy 600

Description: Stress distribution in a random polycrystalline material (Alloy 600) was studied using a topologically correct microstructural model. Distributions of von Mises and hydrostatic stresses at the grain vertices, which could be important in intergranular stress corrosion cracking, were analyzed as functions of microstructure, grain orientations and loading conditions. Grain size, shape, and orientation had a more pronounced effect on stress distribution than loading conditions. At grain vertices the stress concentration factor was higher for hydrostatic stress (1.7) than for von Mises stress (1.5). The stress/strain distribution in the volume (grain interiors) is a normal distribution and does not depend on the location of the studied material volume i.e., surface vs/bulk. The analysis of stress distribution in the volume showed the von Mises stress concentration of 1.75 and stress concentration of 2.2 for the hydrostatic pressure. The observed stress concentration is high enough to cause localized plastic microdeformation, even when the polycrystalline aggregate is in the macroscopic elastic regime. Modeling of stresses and strains in polycrystalline materials can identify the microstructures (grain size distributions, texture) intrinsically susceptible to stress/strain concentrations and justify the correctness of applied stress state during the stress corrosion cracking tests. Also, it supplies the information necessary to formulate the local failure criteria and interpret of nondestructive stress measurements.
Date: April 1995
Creator: Kozaczek, K. J.; Petrovic, B. G.; Ruud, C. O. & Mcllree, A. R.
Partner: UNT Libraries Government Documents Department

Inhibition of stress corrosion cracking of Alloy X-750 by prestrain

Description: Tests of precracked and as-notched compact tension specimens were conducted in 3600C hydrogenated water to determine the effect of prestrain on the stress corrosion cracking (SCC) resistance of Alloy X-750 in the HTH, AH and HOA heat treated conditions. Prestraining is defined as the intentional application of an initial load (or strain) that is higher than the final test load. Prestrain was varied from 10% to 40% (i.e., the initial to final load ratios ranged from 1.1 to 1.4). Other variables included notch root radius, stress level and irradiation. Specimens were bolt-loaded to maintain essentially constant displacement conditions during the course of the test. The frequent heat up and cooldown cycles that were necessary for periodic inspections provided an opportunity to evaluate the effect of test variables on rapid low temperature crack propagation to which this alloy is subject. For Condition HTH, application of 20% to 40% prestrain either eliminates or significantly retards SCC initiation in as-notched specimens and the onset of crack growth in precracked specimens. In addition, this procedure reduces the propensity for low temperature crack growth during cooldown. Similar results were observed for precracked HOA specimens. Application of 20% prestrain also retards SCC in as-notched and precracked AH specimens, but the effects are not as great as in Condition HTH. Prestraining at the 10% level was found to produce an inconsistent benefit. In-reactor SCC testing shows that prestrain greatly improves the in-flux and out-of-flux SCC resistance of Condition HTH material. No SCC was observed in precracked specimens prestrained 30%, whereas extensive cracking was observed in their nonprestrain counterparts.
Date: March 1, 1997
Creator: Mills, W.J.; Lebo, M.R. & Kearns, J.J.
Partner: UNT Libraries Government Documents Department

Creep of nickel-base alloys in high temperature water

Description: Creep tests were performed to compare the creep behavior of commercial nickel-base alloys as a function of stress, temperature, and the environment. The results support earlier work that showed that low carbon alloys are more susceptible to creep and intergranular cracking than are high carbon alloys. Results also show a smaller influence of a water environment on the creep rate of commercial, creep-resistant alloys compared to high purity alloys.
Date: August 1, 1999
Creator: Fish, J.S.; Attanasio, S.A.; Krasodomski, H.T.; Wilkening, W.W.; Was, G.S.; Cookson, J. et al.
Partner: UNT Libraries Government Documents Department

COUPLED MULTI-ELECTRODE INVESTIGATION OF CREVICE CORROSION OF 316 STAINLESS STEEL

Description: Crevice corrosion is currently studied using either one of two techniques depending on the data needed. The first method is a multi-crevice former over a metallic sample; this provides information on the severity of crevice corrosion (depth, position, frequency) but delivers little to no electrochemical information [1]. The second method involves the potentiodynamic or potentiostatic study of an uncreviced sample in model crevice solution or under a crevice former in aggressive solution [2]. Crevice corrosion is highly dependent on the position in the crevice. The distance from the crevice mouth will affect the depth of attack, the solution composition and pH, and the ohmic drop and the true potential in the crevice [3-6]. These in turn affect the current density as a function of potential and position. An Multi-Channel Micro-Electrode Analyzer' (MMA) has been recently used to demonstrate the interaction between localized corrosion sites (pitting corrosion and intergranular corrosion) [7]. MMA can provide spatial resolution of electrochemical properties in the crevice. By coupling such a tool with scaling laws derived from experimental data (a simple equation linking the depth of crevice corrosion initiation to the crevice gap), it is possible to produce highly instrumented crevices, rescaled to enable spatial resolution of local corrosion processes. In this study, the use of multi-wires arrays (up to 100 closed packed wires simulating a planar electrode, divided in 10 distinctively controllable groups) electrically coupled through zero resistance ammeters enables the observation of the current evolution as a function of position inside and outside the crevice. For instance, the location of crevice initiation sites and propagation behavior can be studied under various conditions. Experiments can be conducted with various realistic variables. These can either be electrochemical (such as proximate cathode) or physical (crevice former material or position). Using new impedance-capable MMA, it is also possible ...
Date: January 30, 2006
Creator: F. Bocher, J. R. Scully
Partner: UNT Libraries Government Documents Department

COUPLED MULTI-ELECTRODE INVESTIGATION OF CREVICE CORROSION OF 316 STAINLESS STEEL

Description: Crevice corrosion is currently studied using either one of two techniques depending on the data needed. The first method is a multi-crevice former over a metallic sample; this provides information on the severity of crevice corrosion (depth, position, frequency) but delivers little to no electrochemical information [1]. The second method involves the potentiodynamic or potentiostatic study of an uncreviced sample in model crevice solution or under a crevice former in aggressive solution [2]. Crevice corrosion is highly dependent on the position in the crevice. The distance from the crevice mouth will affect the depth of attack, the solution composition and pH, and the ohmic drop and the true potential in the crevice [3-6]. These in turn affect the current density as a function of potential and position. A Multi-Channel Micro-Electrode Analyzer (MMA) has been recently used to demonstrate the interaction between localized corrosion sites (pitting corrosion and intergranular corrosion) [7]. MMA can provide spatial resolution of electrochemical properties in the crevice. By coupling such a tool with scaling laws derived from experimental data (a simple equation linking the depth of crevice corrosion initiation to the crevice gap), it is possible to produce highly instrumented crevices, rescaled to enable spatial resolution of local corrosion processes. In this study, the use of multi-wires arrays (up to 100 closed packed wires simulating a planar electrode, divided in 10 distinctively controllable groups) electrically coupled through zero resistance ammeters enables the observation of the current evolution as a function of position inside and outside the crevice. For instance, the location of crevice initiation sites and propagation behavior can be studied under various conditions. Experiments can be conducted with various realistic variables. These can either be electrochemical (such as proximate cathode) or physical (crevice former material or position). Using new impedance-capable MMA, it is also possible ...
Date: January 30, 2006
Creator: Scully, F. Bocher and J. R.
Partner: UNT Libraries Government Documents Department

Microstructural dependence of cavitation damage in polycrystalline materials. Final report, 1 November 1992--31 October 1994

Description: Microstructure of a sample of Inconel X-750 damaged by ISCC (intergranular stress corrosion cracking) was examined after fatigue precracking in a high-temperature environment of deaerated water. Orientation imaging microscopy was used to reveal the microstructure adjacent to the crack path. General high-angle boundaries were found to be most susceptible to cracking. An ordering of the susceptibilities to ISCC damage was proposed; all boundaries have been classified into one of 12 categories. A model is proposed to predict the crack path for ISCC based on ex situ record of damage probabilities. The cracking is modeled as a Markov chain on a regular hexagonal array of grain boundaries representing the connectivity of the network.
Date: February 5, 1996
Creator: Adams, B.L.
Partner: UNT Libraries Government Documents Department

Corrosion resistance of inconel 690 to sodium carbonate, calcium carbonate, and sodium meta silicate at 900 and 1100{degrees}C

Description: Corrosive attack of Inconel 690 coupons was not observed following 3 day exposure tests to calcium carbonate, sodium carbonate, and sodium meta silicate at 900 {degrees}C. However, melt line attack was evident on coupons exposed to sodium meta silicate and sodium carbonate tested for 3 days at 1100 {degrees}C. In addition, intergranular attack (IGA), approximately 0.67 mils/day, was observed on the Inconel 690 coupon exposed to calcium carbonate at 1100 {degrees}C. Calcium carbonate did not completely remove the glass coating at 950 {degrees}C. In fact, it was comparable to the results obtained by exposing a glass coated coupon at 950 {degrees}C in air. Therefore, calcium carbonate is not recommended for cleaning the DWPF melter pour spout. Both sodium carbonate and sodium meta silicate appear to remove most of the glass. However, these cleaning agents will remain on the metal surface following exposure at 950 {degrees}C resulting in very rough surface and a potential for corrosive attack when heated to 1100 {degrees}C.
Date: January 29, 1997
Creator: Imrich, K. J.
Partner: UNT Libraries Government Documents Department

Fracture toughness of Alloy 690 and EN52 weld in air and water

Description: The effect of low and high temperature water with high hydrogen on the fracture toughness of Alloy 690 and its weld, EN52, was characterized using elastic-plastic J{sub IC} methodology. While both materials display excellent fracture resistance in air and elevated temperature (>93 C) water, a dramatic degradation in toughness is observed in 54 C water. The loss of toughness is associated with a hydrogen-induced intergranular cracking mechanism where hydrogen is picked up from the water. Comparison of the cracking behavior in low temperature water with that for hydrogen-precharged specimens tested in air indicates that the critical local hydrogen content required to cause low temperature embrittlement is on the order of 120 to 160 ppm. Loading rate studies show that the cracking resistance is significantly improved at rates above ca. 1000 MPa{radical}m/h because there is insufficient time to produce grain boundary embrittlement. Electron fractographic examinations were performed to correlate cracking behavior with microstructural features and operative fracture mechanics.
Date: June 1, 1999
Creator: Brown, C.M. & Mills, W.J.
Partner: UNT Libraries Government Documents Department

Radiation hardening effects on localized deformation and stress corrosion cracking of stainless steels

Description: Radiation hardening in austenitic stainless steels modifies deformation characteristics and correlate well with increased susceptibility to intergranular stress corrosion cracking (IGSCC). Available data on neutron-irradiated materials have been analyzed and correlations developed between fluence, yield strength, and cracking susceptibility in high-temperature water environments. Large heat-to-heat differences in critical fluence (0.2 to 2.5 {times} 10{sup 21} n/cm{sup 2}) for IGSCC are documented. In many cases, this variability is consistent with yield strength differences among irradiated materials. IGSCC correlates better to yield strength than to fluence for most heats suggesting a possible role of radiation-induced hardening (and microstructure) on cracking. Microstructural evolution during proton and heavy-ion irradiation has been characterized in low-carbon 302SSs. Hardening results from dislocation loops. SEM and TEM are used to examine dose, strain, and temperature effects on deformation. This hardened microstructure produces inhomogeneous planar deformation within the matrix. Regularly spaced steps are created at the surface during deformation which increase in number with increasing macroscopic strain. Twinning is the dominant deformation mechanism at low temperature, while dislocation channeling is observed at 288C. Deformation characteristics are discussed in terms of potential impact on IGSCC.
Date: August 1, 1993
Creator: Bruemmer, S. M.; Cole, J. I.; Brimhall, J. L.; Carter, R. D. & Was, G. S.
Partner: UNT Libraries Government Documents Department

Effect of chloride content of molten nitrate salt on corrosion of A516 carbon steel.

Description: The corrosion behavior of A516 carbon steel was evaluated to determine the effect of the dissolved chloride content in molten binary Solar Salt. Corrosion tests were conducted in a molten salt consisting of a 60-40 weight ratio of NaNO{sub 3} and KNO{sub 3} at 400{sup o}C and 450{sup o}C for up to 800 hours. Chloride concentrations of 0, 0.5 and 1.0 wt.% were investigated to determine the effect on corrosion of this impurity, which can be present in comparable amounts in commercial grades of the constituent salts. Corrosion rates were determined by descaled weight losses, corrosion morphology was examined by metallographic sectioning, and the types of corrosion products were determined by x-ray diffraction. Corrosion proceeded by uniform surface scaling and no pitting or intergranular corrosion was observed. Corrosion rates increased significantly as the concentration of dissolved chloride in the molten salt increased. The adherence of surface scales, and thus their protective properties, was degraded by dissolved chloride, fostering more rapid corrosion. Magnetite was the only corrosion product formed on the carbon steel specimens, regardless of chloride content or temperature.
Date: November 1, 2010
Creator: Bradshaw, Robert W. & Clift, W. Miles
Partner: UNT Libraries Government Documents Department

Fused Fluoride--Inconel System Under Cyclotron Irradiation--Preliminary Results

Description: The fused fluoride-Inconel reactor system was studied under irradiation with nominal 19 Mev deuterons as supplied by the Berkeley 60-inch cyclotron. Chemical, metallographic, magnetic susceptibility, electron diffraction and X-ray diffraction studies were made on the as-received materials, one control run and two irradiated runs. No changes in the fused fluoride fuel were noted. Accelerated intergranular corrosion and increased grain size were observed in the irradiated Inconel specimens. This report is based upon studies conducted for the Atomic Energy Commission under Contract AT-40-1-GEN-1064.
Date: December 17, 1951
Creator: Goeddel, W.V. & Epp, Jr., A.A.
Partner: UNT Libraries Government Documents Department

Modeling of grain boundary stresses in Alloy 600

Description: Corrosive environments combined with high stress levels and susceptible microstructures can cause intergranular stress corrosion cracking (IGSCC) of Alloy 600 components on both primary and secondary sides of pressurized water reactors. One factor affecting the IGSCC is intergranular carbide precipitation controlled by heat treatment of Alloy 600. This study is concerned with analysis of elastic stress fields in vicinity of M{sub 7}C{sub 3} and M{sub 23}C{sub 6} carbides precipitated in the matrix and at a grain boundary triple point. The local stress concentration which can lead to IGSCC initiation was studied using a two-dimensional finite element model. The intergranular precipitates are more effective stress raisers than the intragranular precipitates. The combination of the elastic property mismatch and the precipitate shape can result in a local stress field substantially different than the macroscopic stress. The maximum local stresses in the vicinity of the intergranular precipitate were almost twice as high as the applied stress.
Date: April 1995
Creator: Kozaczek, K. J.; Sinharoy, A.; Ruud, C. O. & Mcllree, A. R.
Partner: UNT Libraries Government Documents Department

Status report: Intergranular stress corrosion cracking of BWR core shrouds and other internal components

Description: On July 25, 1994, the US Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 94-03 to obtain information needed to assess compliance with regulatory requirements regarding the structural integrity of core shrouds in domestic boiling water reactors (BWRs). This report begins with a brief description of the safety significance of intergranular stress corrosion cracking (IGSCC) as it relates to the design and function of BWR core shrouds and other internal components. It then presents a brief history of shroud cracking events both in the US and abroad, followed by an indepth summary of the industry actions to address the issue of IGSCC in BWR core shrouds and other internal components. This report summarizes the staff`s basis for issuing GL 94-03, as well as the staff`s assessment of plant-specific responses to GL 94-03. The staff is continually evaluating the licensee inspection programs and the results from examinations of BWR core shrouds and other internal components. This report is representative of submittals to and evaluations by the staff as of September 30, 1995. An update of this report will be issued at a later date.
Date: March 1, 1996
Partner: UNT Libraries Government Documents Department

Corrosion of current-collector materials in Li-ion cells

Description: The primary current-collector materials being used in lithium-ion cells are susceptible to environmental degradation: aluminum to pitting corrosion and copper to environmentally assisted cracking. Pitting occurs at the highly oxidizing potentials associated with the positive-electrode charge condition. However, the pitting mechanism is more complex than that typically observed in aqueous systems in that the pits are filled with a mixed metal/oxide product and exist as mounds or nodules on the surface. Electrochemical impedance was shown to be an effective analytical tool for quantification and verification of visual observations and trends. Two fluorocarbon-based coatings were shown to improve the resistance of Al to localized pitting. Finally, environmental cracking of copper can occur at or near the lithium potential and only if specific metallurgical conditions exist (work hardening and large grain size).
Date: December 1, 1996
Creator: Braithwaite, J.; Nagasubramanian, G.; Gonzales, A.; Lucero, S. & Cieslak, W.
Partner: UNT Libraries Government Documents Department

An Investigation of the Mechanism of IGA/SCC of Alloy 600 in Corrosion Accelerating Heated Crevice Environments. Technical Progress Report

Description: OAK-B135 An Investigation of the Mechanism of IGA/SCC of Alloy 600 in Corrosion Accelerating Heated Crevice Environments. Technical Progress Report. This program focuses on understanding the mechanisms causing corrosion damage to steam generator tubes in a pressurized water reactor (PWR) and the effects of the proposed remedial measures. The crevice formed by the tube/tube support plate (T/TSP) intersection in a PWR steam generator is a concentration site for nonvolatile impurities (referred to as hideout) in the steam generator water. The restricted mass transport in the small crevice volume prevents the species, which concentrate during the generation of steam, from quickly dispersing into the bulk water. The concentrated solutions in crevices have been a contributing cause of several forms of corrosion of steam generator tubes including intergranular attack/stress corrosion cracking (IGA/SCC), pitting, and wastage.
Date: January 1, 1999
Creator: Lumsden, Jesse
Partner: UNT Libraries Government Documents Department

An Investigation of the Mechanism of IGA/SCC of Alloy 600 in Corrosion Accelerating Heated Crevice Environments. Technical Progress Report

Description: This program focuses on understanding mechanisms causing corrosion damage to steam generator tubes in a pressurized water reactor (PWR). The crevice formed by the tube/tube support plate (T/TSP) intersection in a PWR steam generator is a concentration site for nonvolatile impurities (referred to as hideout) in the steam generator water. The restricted mass transport in the small crevice volume prevents the species, which concentrate during the generation of steam, from quickly dispersing into the bulk water. The concentrated solutions in crevices have been a contributing cause of several forms of corrosion of steam generator tubes including intergranular attack/stress corrosion cracking (IGA/SCC), pitting, and wastage.
Date: November 1, 1999
Creator: Lumsden, Jessee
Partner: UNT Libraries Government Documents Department

An investigation of the mechanism of IGA/SCC of alloy 600 in corrosion accelerating heated crevice environments. Quarterly Technical Progress Report No. 4 for the period May 1, 2000 through July 31, 2000

Description: OAK-B135 An investigation of the mechanism of IGA/SCC of alloy 600 in corrosion accelerating heated crevice environments. Quarterly Technical Progress Report No. 4 for the period May 1, 2000 through July 31, 2000
Date: July 31, 2000
Creator: Lumsden, Dr. Jesse
Partner: UNT Libraries Government Documents Department

Tensile stress corrosion cracking of type 304 stainless steel irradiated to very high dose

Description: Certain safety-related core internal structural components of light water reactors, usually fabricated from Type 304 or 316 austenitic stainless steels (SSs), accumulate very high levels of irradiation damage (20--100 displacement per atom or dpa) by the end of life. The data bases and mechanistic understanding of, the degradation of such highly irradiated components, however, are not well established. A key question is the nature of irradiation-assisted intergranular cracking at very high dose, i.e., is it purely mechanical failure or is it stress-commotion cracking? In this work, hot-cell tests and microstructural characterization were performed on Type 304 SS from the hexagonal fuel can of the decommissioned EBR-11 reactor after irradiation to {approximately}50 dpa at {approximately}370 C. Slow-strain-rate tensile tests were conducted at 289 C in air and in water at several levels of electrochemical potential (ECP), and microstructural characteristics were analyzed by scanning and transmission electron microcopies. The material deformed significantly by twinning and exhibited surprisingly high ductility in air, but was susceptible to severe intergranular stress corrosion cracking (IGSCC) at high ECP. Low levels of dissolved O and ECP were effective in suppressing the susceptibility of the heavily irradiated material to IGSCC, indicating that the stress corrosion process associated with irradiation-induced grain-boundary Cr depletion, rather than purely mechanical separation of grain boundaries, plays the dominant role. However, although IGSCC was suppressed, the material was susceptible to dislocation channeling at low ECP, and this susceptibility led to poor work-hardening capability and low ductility.
Date: September 1, 2001
Creator: Chung, H. M.; Ruther, W. E.; Strain, R. V. & Shack, W. J.
Partner: UNT Libraries Government Documents Department

Eddy Current Signature Classification of Steam Generator Tube Defects Using A Learning Vector Quantization Neural Network

Description: A major cause of failure in nuclear steam generators is degradation of their tubes. Although seven primary defect categories exist, one of the principal causes of tube failure is intergranular attack/stress corrosion cracking (IGA/SCC). This type of defect usually begins on the secondary side surface of the tubes and propagates both inwards and laterally. In many cases this defect is found at or near the tube support plates.
Date: January 3, 2005
Creator: Garcia, Gabe V.
Partner: UNT Libraries Government Documents Department