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Investigation On The Evaluation Of Cleavage Fracture Toughness Using Pccv Specimens In The Ductile Brittle Transition Range Of Reactor Pressure Vessel Steels Contract Research
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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 Technical Publications by JAERI Staff in ... by : Nihon Genshiryoku Kenkyujo
Download or read book Technical Publications by JAERI Staff in ... written by Nihon Genshiryoku Kenkyujo and published by . This book was released on 1998 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Metals Abstracts written by and published by . This book was released on 1998-04 with total page 1176 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 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 Dynamic Fracture Toughness Measurements in the Ductile-to- Brittle Region Using Small Specimens by : RE. Link
Download or read book Dynamic Fracture Toughness Measurements in the Ductile-to- Brittle Region Using Small Specimens written by RE. Link and published by . This book was released on 2003 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic fracture toughness of a reactor pressure vessel steel was investigated using small specimens. Precracked Charpy-size SE(B) specimens and circumferentially cracked round bars (CRB) loaded in tension were used to investigate the dynamic fracture toughness of an A533, Gr. B steel plate within the ductile-brittle transition region. The specimens used in this investigation were removed from the broken halves of conventional 4T C(T) specimens that had been utilized in a previous investigation of the dynamic fracture toughness of this material. Crack-tip loading rates in excess of 104 MPa-m1/2/s were achieved in the current tests. Multiple specimens were tested at each temperature in order to permit the determination of the reference temperature, T0. A fracture toughness scaling model for the circumferentially cracked round bar developed by Sciabetta was used to account for the loss of constraint in this specimen. A master curve approach was used to characterize the dynamic toughness in the ductile-brittle region. The shift in transition temperature was compared to a model for the strain rate dependence of T0 developed by Wallin. The shift in transition temperature of the CRB specimen was accurately predicted by the model. The CRB specimen and the dynamic SE(B) specimens gave good results considering the material inhomogeneity typical of the plate tested.
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 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 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 Experimental Study of the Fracture Toughness Transferability to Pressurized Thermal Shock Representative Loading Conditions by : M. Scibetta
Download or read book Experimental Study of the Fracture Toughness Transferability to Pressurized Thermal Shock Representative Loading Conditions written by M. Scibetta and published by . This book was released on 2008 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fracture toughness testing on standard specimens in the ductile to brittle transition regime is well established and was first standardized by ASTM in 1997. However, its applicability to structural components and its potential conservatism, due to the high constraint condition in standard specimens, remain a subject of concern. In this work a study of the transferability of the fracture toughness measurements from laboratory specimens to structural components is performed. The structural component of interest is the Reactor Pressure Vessel subjected to an accidental loading condition called Pressurized Thermal Shock (PTS). As the actual component cannot be reasonably tested, an original experimental set-up is developed to simulate PTS representative loading conditions. A semi-elliptical crack is introduced by fatigue in a disk shape specimen which is biaxial loaded in the ductile to brittle transition regime. The developed disk specimen is called PTS-D specimen. Master Curve tests on 15 PTS-D specimens are performed and compared to standard size specimens having deep and shallow cracks. The reference temperature obtained on PTS-D is equivalent to the one obtained on half-inch compact tension specimens. To support the experimental results, finite element calculations are performed. It turns out that, in the tested range, constraint in PTS-D specimens is high. However, loss of constraint appears earlier than in standard specimens. It is found that the Beremin approach combined with analytical tool allows rationalizing all test results.
Book Synopsis Fracture Toughness Measurements in the Transition Region Using Sub-Size Precracked Charpy and Cylindrical Bar Specimens by : E. van Walle
Download or read book Fracture Toughness Measurements in the Transition Region Using Sub-Size Precracked Charpy and Cylindrical Bar Specimens written by E. van Walle and published by . This book was released on 2002 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the study presented here is the validation of direct fracture toughness measurements using two small-size geometries, which can be obtained from machining broken Charpy-V specimens: • the miniaturized precracked Charpy-V specimen (MPCCv); • the miniaturized Cracked Round Bar (MCRB). Fracture toughness results have been obtained in the ductile-to-brittle transition regime for two well-characterized reactor pressure vessel steels, and compared using the Master Curve analysis to reference data measured using bigger samples of the more conventional C(T) geometry.
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 Applicability of Sub-Charpy-Size Bend and Impact Specimens for Estimation of Fracture Toughness in the Transition Region by : M. Nevalainen
Download or read book Applicability of Sub-Charpy-Size Bend and Impact Specimens for Estimation of Fracture Toughness in the Transition Region written by M. Nevalainen and published by . This book was released on 1999 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of a test program to introduce small specimen test techniques, fracture toughness tests have been performed with 20% side-grooved small (10•10•55 mm) and "ultra-small" (3•4•27, 5•5•27 and 5•10•55 mm) specimens. The objectives were to evaluate the measuring capacity of small specimens and to verify the applicability of the statistical cleavage fracture model of VTT for such test data. Two pressure vessel steels were used in the study. Most of the tests were performed in the transition range and ended at cleavage fracture, but some tests were also conducted in the temperature range of ductile tearing. According to the measured data, the 100 MPa?m reference temperatures (T0), determined even with 3•4 mm specimens, are in good agreement with those of the larger specimens. The statistical specimen size correction only was applied in the analyses, i.e., without any consideration of specimen constraint. The measurements made in the ductile range indicate that practically similar fracture resistance curves can be obtained with the 5•10 mm and larger specimens up to the J-level of 500 kN/m. Also, correlations have been developed, by applying a fracture mechanics approach, for estimating the Charpy transition temperatures of ferritic structural steels from small specimen test data. The correlations were verified by analyzing test data produced with Charpy (ISO-V) and KLST-type subsize specimens (3•4•27 mm). Two energy criterion combinations were applied for determining transition temperatures, i.e., the criteria based on the area of the specimen ligament, being in accordance with the master curve definition, and those derived from an empirical mean relationship found between the upper-shelf energies measured with ISO-V and KLST specimens for various steels. The results show that both of these criteria can be used to give a satisfactory correlation between the transition temperatures and that the standard deviations of the correlations are approximately equal, i.e., around 15°C. A method is proposed for estimating the Charpy upper-shelf energy from subsize specimen data.
Book Synopsis An Investigation of Fracture Toughness, Fatigue-crack Growth, Sustained-load Flaw Growth, and Impact Properties of Three Pressure Vessel Steels by : Charles Michael Hudson
Download or read book An Investigation of Fracture Toughness, Fatigue-crack Growth, Sustained-load Flaw Growth, and Impact Properties of Three Pressure Vessel Steels written by Charles Michael Hudson and published by . This book was released on 1975 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Micromechanical Prediction of Fracture Toughness for Pressure Vessel Steel Using a Coupled Model by : MR. Goldthorpe
Download or read book Micromechanical Prediction of Fracture Toughness for Pressure Vessel Steel Using a Coupled Model written by MR. Goldthorpe and published by . This book was released on 1999 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: A method of analyzing the ductile to brittle transition region of a ferritic steel using a coupled micromechanical model of ductile damage, stable crack growth and cleavage fracture has been developed to improve the definition of upper shelf behavior for actual structures. Ductile damage is modelled using the Gurson model as modified by Tvergaard, along with a specially developed crack growth user element. The probability of cleavage fracture is predicted by post-processing the finite element results using the Beremin model of cleavage fracture. Predictions are made of ductile tearing and cleavage fracture in test specimen and wide plate configurations of A533B steel for a range of temperatures. The coupled model is capable of predicting transition toughness and transition temperature shifts for different levels of structural constraint. An analytically-based definition of the onset of upper shelf temperature (OUST) is the temperature at which the coupled ductile damage/cleavage fracture model predicts a probability of failure by cleavage fracture of 5%. Estimates of the shift in the OUST due to different levels of in-plane crack tip constraint are made using the elastic T-stress as a measure of constraint. There is potential for using the T-stress as a measure of structural constraint in order to determine shifts in transition temperature for materials with degraded toughness.
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:
Book Synopsis Temperature Dependence of the Fracture Toughness and the Cleavage Fracture Strength of a Pressure Vessel Steel by : H. Kotilainen
Download or read book Temperature Dependence of the Fracture Toughness and the Cleavage Fracture Strength of a Pressure Vessel Steel written by H. Kotilainen and published by . This book was released on 1980 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new model for the temperature dependence of the fracture toughness has been sought. It is based on the yielding processes at the crack tip, which are thought to be competitive with fracture. Using this method a good correlation between measured and calculated values of fracture toughness has been found for a Cr-Mo-V pressure vessel steel as well as for A533B. It has been thought that the application of this method can reduce the number of surveillance specimens in nuclear reactors.
