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Investigation Of Transition Fracture Toughness Variation Within The Thickness Of Reactor Pressure Vessel Forgings
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Book Synopsis Investigation of Transition Fracture Toughness Variation Within the Thickness of Reactor Pressure Vessel Forgings by : Enrico Lucon
Download or read book Investigation of Transition Fracture Toughness Variation Within the Thickness of Reactor Pressure Vessel Forgings written by Enrico Lucon and published by . This book was released on 2010 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation has been conducted on the influence of the through-thickness sampling position on the tensile and fracture toughness properties of reactor pressure vessel forgings, using material from two actual pressurized water reactor vessels. The aim was to quantify the safety margins entailed by extracting surveillance samples from the 1/4T and 3/4T positions, as recommended by the current legislation. For each forging, seven layers have been considered: Inner surface, 1/8T, 1/4T, 1/2T, 3/4T, 7/8T, and outer surface; for each position, two tensile tests at room temperature and 16 fracture toughness tests in the ductile-to-brittle transition region have been performed. In terms of tensile properties, for both forgings the strength is higher at the surfaces than in the centre, while ductility (elongations and reduction of area) is substantially unaffected. For both materials, fracture toughness is better at the surfaces than in the central portion, although differences in terms of Master Curve reference temperatures are statistically not relevant at the 95 % confidence level. This effect is more pronounced for one of the materials, due to the larger amount of material removed with respect to the original heat-treated forging, and is qualitatively confirmed by metallographic observations. The results obtained from this study are in substantial agreement with similar studies found in the literature, although most authors have reported larger differences between surface and central layers.
Book Synopsis INVESTIGATION ON THE EVALUATION OF CLEAVAGE FRACTURE TOUGHNESS USING PCCv SPECIMENS IN THE DUCTILE-BRITTLE TRANSITION RANGE OF REACTOR PRESSURE VESSEL STEELS - (CONTRACT RESEARCH) by : Kunio Onizawa
Download or read book INVESTIGATION ON THE EVALUATION OF CLEAVAGE FRACTURE TOUGHNESS USING PCCv SPECIMENS IN THE DUCTILE-BRITTLE TRANSITION RANGE OF REACTOR PRESSURE VESSEL STEELS - (CONTRACT RESEARCH) written by Kunio Onizawa and published by . This book was released on 1997 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modeling the Ductile Brittle Fracture Transition in Reactor Pressure Vessel Steels Using a Cohesive Zone Model Based Approach by :
Download or read book Modeling the Ductile Brittle Fracture Transition in Reactor Pressure Vessel Steels Using a Cohesive Zone Model Based Approach written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fracture properties of Reactor Pressure Vessel (RPV) steels show large variations with changes in temperature and irradiation levels. Brittle behavior is observed at lower temperatures and/or higher irradiation levels whereas ductile mode of failure is predominant at higher temperatures and/or lower irradiation levels. In addition to such temperature and radiation dependent fracture behavior, significant scatter in fracture toughness has also been observed. As a consequence of such variability in fracture behavior, accurate estimates of fracture properties of RPV steels are of utmost importance for safe and reliable operation of reactor pressure vessels. A cohesive zone based approach is being pursued in the present study where an attempt is made to obtain a unified law capturing both stable crack growth (ductile fracture) and unstable failure (cleavage fracture). The parameters of the constitutive model are dependent on both temperature and failure probability. The effect of irradiation has not been considered in the present study. The use of such a cohesive zone based approach would allow the modeling of explicit crack growth at both stable and unstable regimes of fracture. Also it would provide the possibility to incorporate more physical lower length scale models to predict DBT. Such a multi-scale approach would significantly improve the predictive capabilities of the model, which is still largely empirical.
Book Synopsis Trends in Reactor Pressure Vessel and Circuit Development by : R. W. Nichols
Download or read book Trends in Reactor Pressure Vessel and Circuit Development written by R. W. Nichols and published by Elsevier Science & Technology. This book was released on 1980 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Reference Fracture Toughness Procedures Applied to Pressure Vessel Materials by : American Society of Mechanical Engineers. Winter Annual Meeting
Download or read book Reference Fracture Toughness Procedures Applied to Pressure Vessel Materials written by American Society of Mechanical Engineers. Winter Annual Meeting and published by . This book was released on 1984 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of Strain Effect on Cleavage Fracture for Reactor Pressure Vessel Material by : Dr.Kushal Bhattacharyya
Download or read book Investigation of Strain Effect on Cleavage Fracture for Reactor Pressure Vessel Material written by Dr.Kushal Bhattacharyya and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Failure mechanism of 20MnMoNi55 steel in the lower self of ductile to brittle transition (DBT) region is considered as brittle fracture but it has been observed from the experimental analysis of stress-strain diagram that clear plastic deformation is shown by the material before failure. Therefore, strain correction is implemented in the cleavage fracture model proposed by different researchers in the lower self of the DBT region with the help of finite element analysis. To avoid a huge number of experiments being performed, Monte Carlo simulation is used to generate a huge number of random data at different temperatures in the lower self of the DBT region for calibration of the cleavage parameters with the help of the master curve methodology. Fracture toughness calculated after strain correction through different models are validated with experimental results for the different probability of failures.
Book Synopsis Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels by : Lendell E. Steele
Download or read book Neutron Irradiation Embrittlement of Reactor Pressure Vessel Steels written by Lendell E. Steele and published by . This book was released on 1975 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Fracture Toughness Measurements in the Transition Regime Using Small Size Samples by : R. Chaouadi
Download or read book Fracture Toughness Measurements in the Transition Regime Using Small Size Samples written by R. Chaouadi and published by . This book was released on 1998 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present paper reports the treatment of fracture toughness data in the ductile-to-brittle transition regime by using Charpy size specimens. Size effect and statistical variation are taken into account according to a statistical model associated to the weakest link model. The methodology is first calibrated on a reference reactor pressure vessel material, for which fracture toughness data obtained on large samples are available. This methodology is successfully applied to a number of RPV steels to determine the fracture toughness behaviour in the transition regime. Monte Carlo simulations are performed to determine the confidence interval of the reference temperature as derived from a small number of tests.
Book Synopsis Temperature Dependence and Variability of Fracture Toughness in the Transition Regime for A508 Grade 4N Pressure Vessel Steel by : T. R. Leax
Download or read book Temperature Dependence and Variability of Fracture Toughness in the Transition Regime for A508 Grade 4N Pressure Vessel Steel written by T. R. Leax and published by . This book was released on 2006 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: A508 Grade 4N is a high nickel (3.4 %) pressure vessel steel with a relatively high yield strength (585 MPa minimum for Class 1) and a relatively low transition temperature (47 J transition temperature of -29°C or below). Published fracture toughness data on this steel are nonexistent, and so they have not been included in prior assessments of the applicability of the Master Curve approach to pressure vessel steels. The purpose of this study is to compare the temperature dependence and data scatter for this steel with the behavior predicted by the Master Curve. The available database consists of approximately 800 fracture toughness tests on 51 material heats, some of which were given a temper embrittling heat treatment. As an additional basis of comparison, test data on A508 Grades 2 and 3, 1 % nickel weld metal, and several high nickel (1.3-3.8 %) steels (NiCrMo and NiCrMoV) were included in the assessment. Maximum likelihood techniques were used to fit the toughness data, and Monte Carlo methods were used to assess the observed distribution of Weibull slopes (related to the extent of variability). The results of this assessment show that the Master Curve provides a good description of the shape (temperature dependence) of the toughness curve for moderate and high transition temperatures. However, for heats with low transition temperatures below the range observed in other pressure vessel steels, the shape of the toughness curve deviates from the Master Curve. The lower the transition temperature, the larger the deviation from the Master Curve. Based on the test data, a model describing the behavior of A508 Grade 4N has been developed. This model also accurately describes the toughness behavior of the other pressure vessel steels included in this study. With respect to variability, the Weibull slope of A508 Grade 4N is consistent with the value of four prescribed by the Master Curve. However, the Weibull slope for the other pressure vessel steels included in this assessment is close to 3.4. This lower value of the Weibull slope, which indicates larger variability, is likely the result of material inhomogeneity.
Book Synopsis Irradiated Dynamic and Arrest Fracture Toughness Compared to Lower-Bound Predictions by : TR. Mager
Download or read book Irradiated Dynamic and Arrest Fracture Toughness Compared to Lower-Bound Predictions written by TR. Mager and published by . This book was released on 1992 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pressure-temperature operating curves for nuclear reactor pressure vessels are based upon a lower-bound fracture toughness curve which bounds rapid load dynamic initiation and crack arrest fracture toughness data. The ASME Boiler and Pressure Vessel Code defines the reference toughness (KIR) curve as this lower bound, and this KIR curve was developed solely from unirradiated dynamic and arrest fracture toughness data from one heat of SA533B-1 steel (HSST Plate 02) and two heats of SA508-2 steel. The effects of radiation embrittlement on the shape and shift of the KIR curve to account for the increase in reference temperature is thought to be conservative, but this conservatism has not been fully verified. This study reviews available data from past dynamic and arrest toughness tests on irradiated vessel steels from test reactor irradiations and compares the data to the shifted KIR curve using the transition temperature shift approach detailed in Regulatory Guide 1.99, Revision 2. Dynamic initiation and crack arrest fracture toughness data are available from only a few irradiated large specimen tests (that is, test specimens with thicknesses greater than about 51 mm [2 in.]); small specimen tests (including precracked Charpy) are used for the other comparisons. The limited results indicate that the Regulatory approach for shifting the KIR curve is very conservative even when the Regulatory Guide 1.99, Revision 2 "margin term" is not used and a correction for fluence rate is ignored. No change in shape for the dynamic toughness and arrest data (in particular for low upper shelf materials) was observed.
Book Synopsis Validation of Surveillance Concepts and Trend Curves by the Investigation of Decommissioned Reactor Pressure Vessels by : Hans-Werner Viehrig
Download or read book Validation of Surveillance Concepts and Trend Curves by the Investigation of Decommissioned Reactor Pressure Vessels written by Hans-Werner Viehrig and published by . This book was released on 2018 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigation of reactor pressure vessel (RPV) material from the decommissioned Greifswald nuclear power plant representing the first generation of Russian-type WWER-440/V-230 reactors offers the opportunity to evaluate the real toughness response. This paper presents test results measured on trepans taken from the multilayer beltline welding seam SN0.1.4 and forged base metal ring 0.3.1 located in the reactor core region of the Unit 4 RPV. This unit was shut down after 11 years of operation. The characterization of the irradiation response was based on the measurement of the hardness, the tensile strength, the master curve reference temperature, T0, and the Charpy-V transition temperature through the thickness of multilayer beltline welding seam SN0.1.4 and the forged base metal ring 0.3.1. For the beltline welding seam we observed a large variation in the through-thickness master curve T0 values. The T0 values measured with the T-S-oriented Charpy size SE(B) specimens strongly depended on the intrinsic welding bead microstructure along the crack tip. The progression of the T0 values through the thickness-forged base metal ring 0.3.1 ranged from 121 to 130C and indicated no irradiation-induced embrittlement within the fluence range of 5.38 to 1.20 1019 n/cm2 (E > 0.5 MeV) through the thickness of the RPV wall. More than the allowed 2 % of the specimen size-adjusted fracture toughness values, KJc-1T, were below the fracture toughness curve for 2 % fracture probability. The reason for the occurrence of very low KJc-1T values was seen in the intergranular planes detected on the fractured surfaces of the specimens. Modified master curve-based evaluation methods indicated the material to be nonhomogeneous. This investigation shows that the measured irradiation response of the investigated RPV materials does not correspond to the forecast according to the current Russian code.
Book Synopsis Study of the Effects of Various Geometrical and Loading Parameters on the Fracture Resistance Behaviour of a Reactor-Grade Pressure Vessel Steel in the Upper Shelf as Well as DBTT Regime by : M. K. Samal
Download or read book Study of the Effects of Various Geometrical and Loading Parameters on the Fracture Resistance Behaviour of a Reactor-Grade Pressure Vessel Steel in the Upper Shelf as Well as DBTT Regime written by M. K. Samal and published by . This book was released on 2015 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unlike mechanical properties, the fracture resistance behaviour of ductile materials depends upon the state of stress existing ahead of the growing crack-tip. For ductile materials, the fracture resistance, expressed in terms of J-R curve, goes on changing with crack growth. The J-R curves are influenced by the specimen geometry, size, crack-depth, and loading and boundary conditions, etc. Another complicacy arises in the ductile-to-brittle transition temperature regime, where the fracture toughness exhibits considerable scatter and dependency upon temperature. For structural integrity analysis of safety-critical components, fracture resistance data are required in the upper-shelf as well as in the transition regime in order to account for the design-basis postulated accidental loading conditions. It may not always be possible to carry out fracture tests on real-life components due to several limitations, including those of irradiation environment apart from the prohibitive cost and time required for the tests. Finite element (FE) analysis of the components with postulated cracks and loading conditions offer an impressive alternative to safety-analysts. In this work, experiments were conducted on two different types of fracture mechanics specimens not only in the upper-shelf but also in the transition regime. The effect of crack-depth on the fracture behaviour was studied using shallow-cracked and deep-cracked specimens. The size effect was studied using specimens with different thickness values. The effect of specimen geometry and loading condition was studied using a compact-tension and a single-edged-notched-bend specimen. For the FE analysis, nonlocal Rousselier's damage model was used. We extensively studied the effects of several variables on the fracture toughness of a ferritic pressure vessel steel, which have not received much attention in the literature. Extensive experiments were conducted to verify the numerical simulation results of nonlocal damage models.
Book Synopsis The Effect of Constraint Due to Out-of-Plane Stress Field on Fracture of Reactor Pressure Vessel Steel--An Experimental and Numerical Study by : D. Detty
Download or read book The Effect of Constraint Due to Out-of-Plane Stress Field on Fracture of Reactor Pressure Vessel Steel--An Experimental and Numerical Study written by D. Detty and published by . This book was released on 1995 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent research on crack-tip constraint on fracture, including the effect of in-plane biaxial stress fields, has led to a two-parameter elastic K-T and elasto-plastic J-Q approach to correlate fracture toughness. These approaches predict a significant influence of biaxial stress state on fracture toughness. In the case of reactor pressure vessels undergoing pressurized thermal shock (PTS), significant stresses induced parallel to the crack front (out-of-plane stresses) offer additional constraint at the crack-tip. In order to evaluate the effect of this out-of-plane stress field on fracture of reactor pressure vessel steels, a unique method for testing a cruciform-type double-edge notch, DEN(T), specimen loaded in biaxial tension was developed. Three-dimensional finite-element analyses were conducted to design the specimen configuration. Details of the experimental and analytical results and the significance of the crack-tip constraint, due to biaxial stress state involving out-of-plane stresses, on the fracture toughness in the transition region are presented.
Book Synopsis Application of Small Specimens to Fracture Mechanics Characterization of Irradiated Pressure Vessel Steels by : DE. McCabe
Download or read book Application of Small Specimens to Fracture Mechanics Characterization of Irradiated Pressure Vessel Steels written by DE. McCabe and published by . This book was released on 1997 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, precracked Charpy V-notch (PCVN) specimens were used to characterize the fracture toughness of unirradiated and irradiated reactor pressure vessel steels in the transition region by means of three-point static bending. Fracture toughness at cleavage instability was calculated in terms of elastic-plastic KJc values. A statistical size correction based upon weakest-link theory was performed. The concept of a master curve was applied to analyze fracture toughness properties. Initially, size-corrected PCVN data from A 533 grade B steel, designated HSST Plate 02, were used to position the master curve and a 5% tolerance bound for KJc data. By converting PCVN data to 1T compact specimen equivalent KJc data, the same master curve and 5% tolerance bound curve were plotted against the Electric Power Research Institute valid linear-elastic KIc database and the ASME lower bound KIc curve. Comparison shows that the master curve positioned by testing several PCVN specimens describes very well the massive fracture toughness database of large specimens. These results give strong support to the validity of KJc. with respect to KIc in general and to the applicability of PCVN specimens to measure fracture toughness of reactor vessel steels in particular. Finally, irradiated PCVN specimens of other materials were tested, and the results are compared to compact specimen data. The current results show that PCVNs demonstrate very good capacity for fracture toughness characterization of reactor pressure vessel steels. It provides an opportunity for direct measurement of fracture toughness of irradiated materials by means of precracking and testing Charpy specimens from surveillance capsules. However, size limits based on constraint theory restrict the operational test temperature range for KJc data from PCVN specimens.
Book Synopsis Fracture Mechanics Characterisation of Forged Base Metal Ring of the Decommissioned Reactor Pressure Vessel of NPP Greifswald WWER-440 Unit 4 by : Hans-Werner Viehrig
Download or read book Fracture Mechanics Characterisation of Forged Base Metal Ring of the Decommissioned Reactor Pressure Vessel of NPP Greifswald WWER-440 Unit 4 written by Hans-Werner Viehrig and published by . This book was released on 2013 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigation of reactor pressure vessel (RPV) material from the decommissioned Greifswald nuclear power plant (NPP) representing the first generation of Russian type WWER-440/V-230 reactors offers the opportunity to evaluate the real toughness response. The Greifswald RPVs represent different material conditions, viz., irradiated, annealed and irradiated, and annealed and re-irradiated. This paper presents test results from measurements of the trepan taken from forged base metal ring 0.3.1. located in the reactor core region of the unit 4 RPV. This unit was shut down after 11 years of operation and represents the irradiated condition. The key part of the testing is focused on determination of the reference temperature T0 following ASTM E1921-10. The T0 of 11 thickness locations from the inner to the outer RPV wall varies between -112°C and -130°C, with a mean value of -121°C. These are very low values for WWER RPV steel irradiated with fluences between 5.4 and 1.2 x 1019 n/cm2 (E > 0.5 MeV) from the inner to the outer RPV wall. The fracture toughness values at cleavage failure KJc measured on LS oriented pre-cracked and side-grooved Charpy size SE(B) specimens from defined thickness locations of the forged ring show strong scatter. More than the allowed 2 % of the specimen size adjusted KJc-1T values lie below the fracture toughness curve for 2 % fracture probability. The application of modified master curve (MC)-based evaluation methods indicates that the material is non-homogeneous. Because of very low KJc values, the Structural Integrity Assessment Procedures for European Industry step 3 evaluation gave a maximum T0SINTAP of -40°C. The multimodal MC evaluation of KJc values from all thickness locations gives a T0MM of -118°C and a standard deviation of 25 K. The course of the fracture toughness curves evaluated via a multimodal approach also does not represent the measured KJc values, as more than 2 % lie below the fracture toughness curve for 2 % fracture probability. The reason for the occurrence of very low KJc values is intergranular planes detected on the fractured surfaces of the specimens.
Book Synopsis Dynamic Initiation Fracture Toughness of a Pressure Vessel Steel in the Transition Region by : SM. Graham
Download or read book Dynamic Initiation Fracture Toughness of a Pressure Vessel Steel in the Transition Region written by SM. Graham and published by . This book was released on 1999 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic fracture toughness of an ASTM A533, Grade B steel plate was determined at several temperatures in the ductile-brittle transition region. Crack-tip loading rates ranged from approximately 103 to 105 MPa?m/s. The fracture toughness was shown to decrease with increased loading rate. The dynamic fracture toughness was compared with results from previous investigations and it was shown that the decrease in toughness due to increased loading rate at the highest test temperature was not as severe as reported in previous investigations. It was also shown that the reference temperature, T0, was a better index of the fracture toughness vs. temperature relationship than the nil-ductility temperature, RTNDT for this material.
Book Synopsis An Approach for Predicting Reference Fracture Toughness in Irradiated Vessel Materials by : W. L. Server
Download or read book An Approach for Predicting Reference Fracture Toughness in Irradiated Vessel Materials written by W. L. Server and published by . This book was released on 1988 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
