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 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement and Modeling of Radiation induced Grain Boundary Segregation in Stainless Steels written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Influence of Pre irradiation Heat Treatments on Thermal Non equilibrium and Radiation induced Segregation Behavior in Model Austenitic Stainless Steel Alloys written by and published by . This book was released on 2002 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of pre-irradiation heat treatments on thermal non-equilibrium grain boundary segregation (TNES) and subsequent radiation-induced grain boundary segregation (RIS) is studied in a series of model austenitic stainless steels. The alloys used for this study are based on AISI 316 stainless steel and have the following nominal compositions: Fe-16Cr-13Ni-1.25Mn (base 316), Fe-16Cr-13Ni-1.25Mn-2.0Mo (316 + Mo) and Fe-16Cr-13Ni-1.25Mn-2.0Mo-0.07P (316 + Mo + P). Samples were heat treated at temperatures ranging from 1100 to 1300 C and cooled at 4 different rates (salt brine quench, water quench, air cool and furnace cool) to evaluate the effect of annealing temperature and quench rate on TNES. The alloys were than processed with the treatment (temperature and cooling rate) that resulted in the maximum Cr enrichment. Alloys with and without the heat treatment to enrich the grain boundaries with Cr were characterized following irradiation to 1 dpa at 400 C with high-energy protons in order to understand the influence of alloying additions and pre-irradiation grain boundary chemistry on irradiation-induced elemental enrichment and depletion profiles. Various mechanistic models will be examined to explain the observed behavior.
Download or read book Measurement and Modeling of Radiation induced Grain Boundary Grain Boundary Segregation in Stainless Steels written by and published by . This book was released on 1995 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Grain boundary radiation-induced segregation (RIS) in Fe-Ni-Cr stainless alloys has been measured and modelled 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 0 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. Impurity segregation (Si and P) was also measured, but only Si enrichment appeared to be radiation-induced. Grain boundary Si levels peaked at an intermediate temperature of (approximately)325°C reaching levels of (approximately)8 at. %. Equilibrium segregation of P was measured in the high-P alloys, but interfacial concentration did not increase with irradiation exposure. Examination of reported RIS in neutron-irradiated stainless steels revealed similar effects of irradiation dose on grain boundary compositional changes for both major alloying and impurity element's. The Inverse Kirkendall model accurately predicted major alloying element RIS in ion- and neutron-irradiated alloys over the wide range of temperature and dose conditions. In addition, preliminary calculations indicate that the Johnson-Lam model can reasonably estimate grain boundary Si enrichment if back diffusion is enhanced.
Download or read book The Influence of Pre Irradiation Heat Treatments on Thermal Non Equilibrium and Radiation Induced Segregation Behavior in Model Austenitic Stainless Steel Alloys written by GS. Was and published by . This book was released on 2004 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of pre-irradiation heat treatments on thermal non-equilibrium grain boundary segregation (TNES) and subsequent radiation-induced grain boundary segregation (RIS) is studied in a series of model austenitic stainless steels. The alloys used for this study are based on AISI 316 stainless steel and have the following nominal compositions: Fe-16Cr-13Ni-1.25Mn (base 316), Fe-16Cr-13Ni-1.25Mn-2.0Mo (316 + Mo) and Fe-16Cr-13Ni-1.25Mn-2.0Mo-0.07P (316 + Mo + P). Samples were heat treated at temperatures ranging from 1100 to 1300°C and cooled at four different rates (salt brine quench, water quench, air cool and furnace cool) to evaluate the effect of annealing temperature and quench rate on TNES. The alloys were then processed with the treatment (temperature and cooling rate) that resulted in the maximum Cr enrichment. Alloys with and without the heat treatment to enrich the grain boundaries with Cr were characterized following irradiation to 1 dpa at 400°C with high-energy protons in order to understand the influence of alloying additions and pre-irradiation grain boundary chemistry on irradiation-induced elemental enrichment and depletion profiles. Various mechanistic models will be examined to explain the observed behavior.
Download or read book The Effect of Molybdenum on the Grain Boundary Segregation of Chromium Exhibited by Austenitic Stainless Steels After Neutron Irradiation in a BWR written by JC. Walmsley and published by . This book was released on 2000 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analytical investigations employing field-emission gun scanning transmission electron microscopy (FEGSTEM) have indicated that the degree of chromium depletion at grain boundaries is less pronounced in AISI type-316 when compared to type-304 stainless steel after neutron irradiation in Boiling Water Reactor (BWR) conditions to a fluence of 1026 n.m-2 (E > 1 MeV). An explanation of this observation is proposed, which is based on the non-equilibrium segregation (NES) theory of grain boundary segregation. NES model predictions for the radiation-induced segregation of chromium and molybdenum in an austenitic matrix are presented together for the first time. The predicted segregation profiles are compared with the FEGSTEM data, whilst the predicted trends as a function of neutron dose are discussed in terms of possible microstructural evolution in a BWR environment. In particular it will be demonstrated how, according to NES theory, the binding of molybdenum to self-interstitial atoms (SIAs) will take precedence over chromium. In turn, the subsequent migration of molybdenum-SIA "complexes" retard the migration of chromium away from the grain boundary, thus moderating the magnitude of radiation-induced chromium depletion.
Download or read book The Modelling of Combined Radiation Induced and Thermal Non Equilibrium Segregation of Chromium in Neutron Irradiated Austenitic Stainless Steels written by CC. Goodwin and published by . This book was released on 1999 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: A model of the radiation-induced segregation (RIS) and thermal non- equilibrium segregation (TNES) at grain boundaries has been established within a phenomenological theory. This model indicates that the magnitude and extent of segregation is dependent upon the formation of solute-point defect complexes that migrate to grain boundaries. Theoretical predictions are made for the TNES and RIS of chromium in austenitic stainless steels for the first time. The results indicate that for TNES, chromium creates a positive binding energy in the complex, and is thus enriched at the grain boundary. For RIS, chromium produces a negative binding energy in the complex, and is thus depleted at the grain boundary. The combined effect of the two segregation mechanisms is discussed in relation to the evolution of the segregation profile exhibited by the grain boundary. The segregation profiles are shown to be illustrative of analytically measured profiles for similarly treated materials.
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 Modeling of Radiation induced Segregation in Austenitic Fe Cr Ni Alloys written by Todd Randall Allen and published by . This book was released on 1997 with total page 926 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solute Segregation and Void Formation on Grain Boundaries in Electron Irradiated Type 316 Stainless Steel written by S. Ohnuki and published by . This book was released on 1985 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiation-induced segregation and void formation on grain boundaries in titanium-modified Type 316 stainless steel were investigated by electron irradiation and X-ray microanalysis (EDX). Strong enrichment and depletion of solutes were observed on grain boundaries during irradiation. Moreover, preferential void formation on grain boundaries occurred and grain boundary migration was induced by the irradiation. These facts indicate that grain boundaries act as preferential sinks for radiation-induced point defects, and the sink behavior may be changed by the development of the segregation under irradiation.
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 Effect of Radiation Induced Segregation on Precipitate Stability and Swelling in Irradiated Alloys written by VA. Pechenkin and published by . This book was released on 1999 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The radiation-induced segregation of alloy components near point defect sinks with a particular attention to Fe-Cr-Ni based alloys is analyzed. The influence of point defect generation rate on temperature ranges of stability for radiation-retarded M23C6 and radiation-induced Ni3Si precipitates in austenitic stainless steels is considered. A method of calculation of steady-state segregation-induced bias in irradiated binary alloys, taking into account Kirkendall forces and drift forces caused by point defect migration and formation energy gradients near sinks, is proposed. Contributions of various forces to the bias in Fe-Cr-Ni and V-Fe alloys are evaluated. The effect of void-precipitate association on swelling is analyzed. The radiation-induced segregation of components and segregation-induced bias for motionless and moving grain boundaries in a Fe-Cr-Ni alloy are calculated by solving the set of coupled diffusion equations for component and point defect concentrations.
Download or read book Influence of Oversized Solute Additions on Radiation Induced Microstructure and Microchemistry in Austenitic Stainless Steel written by GS. Was and published by . This book was released on 2004 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Oversized solute additions (0.3 at% of either Pt or Hf) were found to have a significant effect on microstructural and microchemical evolution in ultra high-purity 316 stainless steel model alloys after proton irradiations at 400°C to nominal doses of 2.5 and 5 dpa. The radiation-induced microstructure of the 316SS base alloy consisted of voids and faulted Frank loops at both dose levels. Platinum addition enhanced void nucleation and increased the loop density and the mean loop diameter. Hafnium addition to 316SS delayed void formation, decreased the mean loop diameter and increased loop density. Grain boundary composition was measured using analytical transmission electron microscopy. Strong radiation-induced grain boundary Cr depletion and Ni enrichment was found in the 316SS base alloy, while oversized element additions reduced segregation levels at low dose. The Pt-doped alloy showed only minor radiation-induced changes in grain boundary composition and no evidence of segregation was observed in the Hf-doped alloy at 2.5 dpa, however, increasing dose resulted in significant radiation-induced segregation in the Hf-doped alloy.
Download or read book Ah vous ne voulez pas rendre vos comptes written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comparison of Observed and Predicted Data on Radiation Induced Grain Boundary Phosphorus Segregation in VVER Type Steels written by AV. Nikolaeva and published by . This book was released on 2000 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The influence of impurity grain boundary segregation on mechanical properties of low-alloy Cr-Ni-Mo steels is discussed. Mechanisms of impurity and alloying effects on grain boundary embrittlement of low-alloy steels are considered. An approach for estimation of radiation enhanced grain boundary segregation kinetics is proposed. The approach takes into account the reduction of dislocation density (from 1x1014 to 1x1013 m-2) due to irradiation that was observed for low-alloy Cr-Ni-Mo steels. The influence of collision cascades on the radiation damage is also considered. Auger spectroscopy is used for grain boundary segregation detection. The contribution of grain boundary embrittlement to mechanical property degradation due to neutron irradiation is assessed.
Download or read book Radiation induced Segregation in Austenitic Stainless Steels written by and published by . This book was released on 1991 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
