Download or read book Isolation of the Role of Radiation induced Segregation in Irradiation assisted Stress Corrosion Cracking of Proton irradiated Austenitic Stainless Steels written by Jeremy Todd Busby and published by . This book was released on 2001 with total page 1008 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Role of Oxides and Impurities in Proton Irradiation Assisted Stress Corrosion Cracking of Stainless Steels written by John Matthew Cookson and published by . This book was released on 1996 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Robust Modeling Tool for Radiation induced Segregation in Austenitic Stainless Steels written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels in Light Water Reactor (LWR) components has been linked to changes in grain boundary composition due to irradiation induced segregation (RIS). This work developed a robust RIS modeling tool to account for thermodynamics and kinetics of the atom and defect transportation under combined thermal and radiation conditions. The diffusion flux equations were based on the Perks model formulated through the linear theory of the thermodynamics of irreversible processes. Both cross and non-cross phenomenological diffusion coefficients in the flux equations were considered and correlated to tracer diffusion coefficients through Manning's relation. The preferential atomvacancy coupling was described by the mobility model, whereas the preferential atom-interstitial coupling was described by the interstitial binding model. The composition dependence of the thermodynamic factor was modeled using the CALPHAD approach. Detailed analysis on the diffusion fluxes near and at grain boundaries of irradiated austenitic stainless steels suggested the dominant diffusion mechanism for chromium and iron is via vacancy, while that for nickel can swing from the vacancy to the interstitial dominant mechanism. The diffusion flux in the vicinity of a grain boundary was found to be greatly influenced by the composition gradient formed from the transient state, leading to the oscillatory behavior of alloy compositions in this region. This work confirms that both vacancy and interstitial diffusion, and segregation itself, have important roles in determining the microchemistry of Fe, Cr, and Ni at irradiated grain boundaries in austenitic stainless steels.
Download or read book The Role of Fine Defect Clusters in Irradiation Assisted Stress Corrosion Cracking of Proton Irradiated 304 Stainless Steel written by GS. Was and published by . This book was released on 2004 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The influence of small defect clusters on irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels has been examined. A CP-304 SS alloy was irradiated with 3.2 MeV protons to 1.0 dpa at 360°C and then annealed for 45 min. to 1 h at temperatures ranging from 400-600°C. Dislocation microstructure was analyzed using both bright field and dark field techniques and cracking susceptibility was measured in an oxygenated water environment. Intergranular cracking was mitigated following annealing at 500°C/45 min. while only the smallest dislocation loops had been removed. Analysis of the slip step bands on the surface of deformed samples indicates that deformation mode may be important in determining cracking susceptibility. Low-temperature irradiation (
Download or read book Radiation Induced Solute Segregation and Stress Corrosion Cracking Study of AISI 304 and AISI 304L Stainless Steels written by WJ. Liu and published by . This book was released on 1994 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiation induced solute segregation (RIS) of chromium, nickel, and minor elements (e.g., Si, P, S, etc.) in the vicinity of grain boundaries and its influences on intergranular stress corrosion cracking (IGSCC) of commercial purity AISI 304 and AISI 304L austenitic stainless steels were investigated in this study. High energy protons were used for producing irradiation environment.
Download or read book Modeling the Effects of Oversize Solute Additions on Radiation Induced Segregation in Austenitic Stainless Steels written by GS. Was and published by . This book was released on 2005 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oversize solute additions to stainless steels hold promise for reducing radiation-induced segregation (RIS), possibly delaying the onset and severity of irradiation-assisted stress-corrosion cracking (IASCC). The Modified Inverse Kirkendall (MIK) model for RIS in austenitic stainless steels was adapted to include the effects of defect trapping, which is expected to be caused by oversized solutes, on RIS. The model accounts for the sensitivity of RIS to both dose rate and temperature. Model results show that the primary contribution to the reduction in RIS occurs through vacancy trapping and recombination with migrating interstitials, requiring strong solute binding energies on the order of 1.0 eV. The maximum reduction in RIS due to defect trapping increases with dose rate and temperature. The general trends of the model are consistent with experimental data from proton and neutron irradiations.
Download or read book Irradiation assisted Stress Corrosion Cracking Behavior of Austenitic Stainless Steels Applicable to LWR Core Internals written by H. M. Chung and published by . This book was released on 2006 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microstructural Processes in Irradiated Materials written by and published by . This book was released on 1998 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radiation Induced Instability of MnS Precipitates and Its Possible Consequences on Irradiation Induced Stress Corrosion Cracking of Austenitic Stainless Steels written by HM. Chung and published by . This book was released on 1999 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation-assisted stress corrosion cracking (IASCC) is a significant materials issue for the light water reactor (LWR) industry and may also pose a problem for fusion power reactors that will use water as coolant. A new metallurgical process is proposed that involves the radiation-induced release into solution of minor impurity elements not usually thought to participate in IASCC. MnS-type precipitates, which contain most of the sulfur in stainless steels, are thought to be unstable under irradiation. First, Mn transmutes strongly to Fe in thermalized neutron spectra. Second, cascade-induced disordering and the inverse Kirkendall effect operating at the incoherent interfaces of MnS precipitates are thought to act as a pump to export Mn from the precipitate into the alloy matrix. Both of these processes will most likely allow S, which is known to exert a deleterious influence on intergranular cracking, to re-enter the matrix. To test this hypothesis, compositions of MnS-type precipitates contained in several unirradiated and irradiated heats of Type 304, 316, and 348 stainless steels (SSs) were analyzed by Auger electron spectroscopy. Evidence is presented that shows a progressive compositional modification of MnS precipitates as exposure to neutrons increases in boiling water reactors (BWRs). As the fluence increases, the Mn level in MnS decreases, whereas Fe level increases. MnS precipitates were also found to be a reservoir of F, an impurity implicated with cracking of F-contaminated shielded-metal- or submerged-arc welds such as BWR core shroud weld.
Download or read book Radiation Hardening Effects on Localized Deformation and Stress Corrosion Cracking of Stainless Steels written by and published by . This book was released on 1993 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 x 1021 n/cm2) 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.
Download or read book Influence of Impurities and Alloying Elements on IASCC in Neutron Irradiated Austenitic Stainless Steels written by M. Kodama and published by . This book was released on 1994 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Slow strain rate tests (SSRTs) and HNO3/Cr6+ corrosion tests of several types stainless steels irradiated to 5.3x1024n/m2 at about 573K, were conducted to evaluate the correlation between irradiation assisted stress corrosion cracking (IASCC) and radiation induced grain boundary segregation.
Download or read book Radiation induced Instability of MnS Precipitates and Its Possible Consequences on Irradiation induced Stress Corrosion Cracking of Austenitic Stainless Steels written by and published by . This book was released on 1996 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Irradiation-assisted stress corrosion cracking (IASCC) is a significant materials issue for the light water reactor (LWR) industry and may also pose a problem for fusion power reactors that will use water as coolant. A new metallurgical process is proposed that involves the radiation-induced release into solution of minor impurity elements not usually thought to participate in IASCC. MnS-type precipitates, which contain most of the sulfur in stainless steels, are thought to be unstable under irradiation. First, Mn transmutes strongly to Fe in thermalized neutron spectra. Second, cascade-induced disordering and the inverse Kirkendall effect operating at the incoherent interfaces of MnS precipitates are thought to act as a pump to export Mn from the precipitate into the alloy matrix. Both of these processes will most likely allow sulfur, which is known to exert a deleterious influence on intergranular cracking, to re-enter the matrix. To test this hypothesis, compositions of MnS-type precipitates contained in several unirradiated and irradiated heats of Type 304, 316, and 348 stainless steels (SSs) were analyzed by Auger electron spectroscopy. Evidence is presented that shows a progressive compositional modification of MnS precipitates as exposure to neutrons increases in boiling water reactors. As the fluence increases, the Mn level in MnS decreases, whereas the Fe level increases. The S level also decreases relative to the combined level of Mn and Fe. MnS precipitates were also found to be a reservoir of other deleterious impurities such as F and O which could be also released due to radiation-induced instability of the precipitates.
Download or read book Effects of Radiation on Materials written by Martin L. Grossbeck and published by ASTM International. This book was released on 2004 with total page 767 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Isolation of Microstructure in Proton Irradiated Steels Topical Report written by and published by . This book was released on 2000 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: OAK B188 Isolation of Microstructure in Proton-Irradiated Steels. Topical Report. Component degradation by irradiation is a primary concern in both current reactor systems as well as advanced designs and concepts where the demand for higher efficiency and performance will be considerably greater. In advanced reactor systems, core components will be expected to operate under increasingly hostile (temperature, pressure, radiation flux, dose, etc.) conditions, The current strategy for assessing radiation effects for the development of new materials is impractical in that the costs and time required to conduct reactor irradiations are becoming increasingly prohibitive, and the facilities for conducting these irradiations are becoming increasingly scarce. The next generation reactor designs will require more extreme conditions (temperature, flux, fluence), yet the capability for conducting irradiations for materials development and assessment in the next 20 years is significantly weaker than over the past 20 years. Short of building new test reactors, what is needed now are advanced tools and capabilities for studying radiation damage in materials that can keep pace with design development requirements. The most successful of these irradiation tools has been high energy (several MeV) proton irradiation. Proton irradiation to several tens of dpa can be conducted in short amounts of time (weeks), with relatively inexpensive accelerators, and result in negligible residual radioactivity. All of these factors combine to provide a radiation damage assessment tool that reduces the time and cost to develop and assess reactor materials by factors of 10-100. What remains to be accomplished, is the application of this tool to specific materials problems and the extension of the technique to a wider range of problems in preparation for advanced reactor materials development and assessment. In this project, we plan to approach the mechanism of irradiation assisted stress corrosion cracking (IASCC) by isolating the irradiated microstructure. This report focuses on the microstructure of proton irradiated stainless steel and model alloys for reactor pressure vessel (RPV) steels.
Download or read book AEM and AES of Radiation induced Segregation in Proton irradiated Stainless Steels written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book IRRADIATION ASSISTED STRESS CORROSION CRACKING OF MODEL AUSTENITIC STAINLESS STEELS IRRADIATED IN THE HALDEN REACTOR NUREG CR 5608 U S NUCLEAR REGULATORY Commission written by U.S. Nuclear Regulatory Commission and published by . This book was released on 1999* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radiation induced Grain Boundary Segregation in Austenitic Stainless Steels written by and published by . This book was released on 1994 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiation-induced segregation (RIS) to grain boundaries in Fe-Ni-Cr-Si stainless alloys has been measured as a function of irradiation temperature and dose. Heavy-ion irradiation was used to produce damage levels from 1 to 20 displacements per atom (dpa) at temperatures from 175 to 550°C. Measured Fe, Ni, and Cr segregation increased sharply with irradiation dose (from G to 5 dpa) and temperature (from 175 to about 350°C). However, grain boundary concentrations did not change significantly as dose or temperatures were further increased. Although interfacial compositions were similar, the width of radiation-induced enrichment or depletion profiles increased consistently with increasing dose or temperature. Impurity segregation (Si and P) was also measured, but only Si enrichment appeared to be radiation-induced. Grain boundary Si peaked at levels approaching 10 at% after irradiation doses to 10 dpa at an intermediate temperature of 325°C. No evidence of grain boundary silicide precipitation was detected after irradiation at any temperature. Equilibrium segregation of P was measured in the high-P alloys, but interfacial concentration did not increase with irradiation exposure. Comparisons to reported RIS in neutron-irradiated stainless steels revealed similar grain boundary compositional changes for both major alloying and impurity elements.
