Download or read book Effect of Warm Prestressing on the Fracture Toughness of Pressure Vessel Steels written by S. Sugino and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Combined Effects of Residual Stress and Warm Prestressing on Cleavage Fracture in Steels written by Karin Rosahl and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: When the structural integrity of the reactor pressure vessel (RPV) in a pressurised water re- actor (PWR) is analysed, certain types of postulated accidents have to be considered. The conditions during a loss-of-coolant accident (LOCA) resemble a warm prestressing (WPS) sce- nario. Warm prestressing refers to a prior overload sequence which in certain circumstances improves the fracture resistance of a ferritic steel structure. Furthermore, a RPV is a welded structure. The welding process gives rise to residual stresses (RS) that can have a significant influence on the integrity of the RPV. Tensile residual stresses are often regarded as unwanted and detrimental. Previous work has not studied the combined effects of WPS and RS on the fracture behaviour of ferritic steel components. The purpose of this dissertation is to explore the combined effects of WPS and RS by means of robust statistical techniques. To describe the effects of WPS, two models are investigated. A local model using the near crack tip stresses and strains (often called the Beremin model) is usually used to predict the fracture probability of as-received material and can be adapted to include the effects of WPS. However, this requires the use of a detailed finite element analysis. The Chell model, on the other hand, is a deterministic model developed to explain the beneficial effects ofWPS on fracture toughness. Using a Monte Carlo (MC) simulation approach, the Chell model is extended to enable failure probability distributions to be determined. The failure probabilities are compared with both experimental data from the literature and results of an experimental test programme on compact tension specimens. It is found that the MCS approach used in conjunction with the Chell model provides robust and accurate predictions of the failure probability following WPS. To extend the analysis to include residual stress, a novel preloading rig model for introducing a known tensile RS into laboratory fracture specimens is investigated. It is found that the Chell model is to be preferred over the Beremin model. The Chell model provides robust and accurate predictions of the fracture behaviour after WPS, yet its application is straight forward and less time expensive than the Beremin model. The combined effects of WPS and a tensile RS field on the failure probabilities can be analysed by combining the Chell model with the preloading rig model and applying a Monte Carlo simulation approach. Contrary to expectations, it is shown that a tensile RS field can have a significant beneficial effect on the failure distribution after WPS.
Download or read book Effects of Warm Pre Stressing on the Transition Toughness Behavior of an A533 Grade B Class 1 Pressure Vessel Steel written by P. Birkett and published by . This book was released on 1990 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is now well recognized that pre-loading a ferritic steel structure at a temperature above its ductile-brittle transition range may result in an effective increase in toughness on loading at a lower temperature where fracture occurs by cleavage. Of particular significance is the fact that cleavage failure has never been reported in a cracked structure at a low temperature, following pre-loading at a higher temperature, for cases where the applied crack driving force was constant or decreasing with time. This is the basis of the so-called "conservative" warm pre-stressing (WPS) principle. Although this principle is of considerable practical importance, much work is still needed to further understand all aspects of WPS phenomena in order that analysts be better able to assess their effects quantitatively in safety cases.
Download or read book Analysis of Warm Prestress Data written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Loading a cracked structure at elevated temperature, or warm prestressing (WPS), enhances its fracture resistance at a lower temperature. Five data sets, comprising 119 unclad pressure vessel steel specimens, were combined to derive correlations for WPS-enhanced fracture toughness (K[sub Ifrac]) in the absence of ductile tearing. New WPS test results for 27 surface flawed specimens, eight subclad flawed specimens, and five strain-aged specimens are discussed. K[sub Ifrac] exceeded non-WPS fracture toughness, K[sub Ic], for all experiments. The WPS data showed that no specimens failed while K was decreasing, and that at least an additional seven percent additional reloading from the minimum value of applied K[sub I] took place prior to final fracture. The data included complete and partial unloading after WPS prior to final fracture. Crack tip 3-dimensional elastic-plastic finite element (3DEPFE) analysis was performed to support statistical analysis of the data. Regression models were compared with the Chell WPS model. Crack tip 3DEPFE analysis indicated that partially unloaded and completely unloaded data should be treated separately, and that the amount of unloading is unimportant for partially unloaded data. The regression models, which use K[sub I] at WPS (K[sub Iwps]) and K[sub Ic] as independent variables, better represented the WPS benefit than did the more complicated Chell model. An adequate accounting was made for constraint in the WPS experiments. The subclad flaw data support the use of the partial unload regression model, provided that some care is taken to represent the effect of intact cladding if present. The effect of strain aging at or below 260 C (500 F) on WPS benefit was of no consequence for the pressure vessel steels and WPS temperatures used to derive the regression models. The presence of ductile tearing precludes the use of the regression models. The regression model for partial unloading accurately predicted the behavior of full scale pressure vessel WPS experiments. All but one of the 174 experiments considered lie above the lower 2[sigma] estimate of the regressions. The experiments all supported Type I WPS, i.e., there was no fracture during cooling until reloading occurred. However, the regression equations apply to the reload, and are inapplicable to Type I WPS.
Download or read book Potential Impact of Enhanced Fracture toughness Data on Pressurized thermal shock Analysis written by and published by . This book was released on 1990 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Heavy Section Steel Technology (HSST) Program is involved with the generation of enhanced'' fracture-initiation toughness and fracture-arrest toughness data of prototypic nuclear reactor vessel steels. These two sets of data are enhanced because they have distinguishing characteristics that could potentially impact PWR pressure vessel integrity assessments for the pressurized-thermal shock (PTS) loading condition which is a major plant-life extension issue to be confronted in the 1990's. Currently, the HSST Program is planning experiments to verify and quantify, for A533B steel, the distinguishing characteristic of elevated initiation-fracture toughness for shallow flaws which has been observed for other steels. Deterministic and probabilistic fracture-mechanics analyses were performed to examine the influence of the enhanced initiation and arrest fracture-toughness data on the cleavage fracture response of a nuclear reactor pressure vessel subjected to PTS loading. The results of the analyses indicated that application of the enhanced K{sub Ia} data does reduce the conditional probability of failure P(F{vert bar}E); however, it does not appear to have the potential to significantly impact the results of PTS analyses. The application of enhanced fracture-initiation-toughness data for shallow flaws also reduces P(F{vert bar}E), but it does appear to have a potential for significantly affecting the results of PTS analyses. The effect of including Type I warm prestress in probabilistic fracture-mechanics analyses is beneficial. The benefit is transient dependent and, in some cases, can be quite significant. 19 refs., 12 figs., 1 tab.
Download or read book The Effect of Constraint on the Fracture Toughness of Reactor Pressure Vessel Steels written by Geena Kaur Rait and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fracture Properties of Specially Heat Treated ASTM A508 Class 2 Pressure Vessel Steel written by DJ. Alexander and published by . This book was released on 1993 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanical properties of ASTM A508 Class 2 pressure vessel steel quenched and tempered to simulate the effects of irradiation have been measured. The tensile, Charpy impact, fracture toughness, and crack arrest properties were measured as a function of temperature. The fracture toughness was measured using 1T, 2T, and 4T compact specimens. The maximum dimensions of the 4T specimens exceeded the test cylinder thickness, so compound specimens were successfully fabricated by electron-beam welding arms to the material. Compact crack arrest specimens were used to determine the arrest toughness. Two sizes of specimens were tested: 150 by 150 by 32 mm and 75 by 75 by 25 mm. The larger specimens used a brittle weld bead and notch as the crack starter. Two different notches (blunt and fatigue precracked) were used with the smaller specimens. The blunt notch was not successful, but the fatigue-precracked specimens provided valid data without the need for warm prestressing. The results from the small fatigue-precracked specimens were consistent with the data from the larger weld-embrittled specimens.
Download or read book Warm Prestressing and Fracture in Pressure Vessel Steels written by C. P. Harris and published by . This book was released on 1986 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effects of Fatigue in the Elastic Regime on the Impact Properties of Nuclear Pressure Vessel Steels and Its Relation to Fracture Toughness written by Robert William Canty and published by . This book was released on 1984 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
Download or read book Interpretation of Irradiation Effects on the Fracture Toughness of a Pressure Vessel Steel in Terms of Crack Tip Stress Analysis written by David Moore Parks and published by . This book was released on 1974 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Potential Effect of Fracture Technology on IPTS Integrated Pressurized Thermal Shock Analysis Fracture Toughness written by and published by . This book was released on 1990 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: A major nuclear plant life extension issue to be confronted in the 1990's is pressure vessel integrity for the pressurized thermal shock (PTS) loading condition. Governing criteria associated with PTS are included in The PTS Rule'' (10 CFR 50.61) and Regulatory Guide 1.154: Format and Content of Plant-Specific Pressurized Thermal Shock Safety Analysis Reports for Pressurized Water Reactors. The results of the Integrated Pressurized Water Reactors. The results of the Integrated Pressurized Thermal Shock (IPTS) Program, along with risk assessments and fracture analyses performed by the NRC and reactor system vendors, contributed to the derivation of the PTS Rule. Over the last several years, the Heavy Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory (ORNL) has performed a series of large-scale fracture-mechanics experiments. The Thermal Shock Experiments (TSE), Pressurized Thermal Shock Experiments (PTSE), and Wide Plate Experiments (WPE) produced K{sub IC} and K{sub Ia} data that suggest increased mean K{sub IC} and K{sub Ia} curves relative to the ones used in the IPTS study. Also, the PTSE and WPE have demonstrated that prototypical nuclear reactor pressure vessel steels are capable of arresting a propagating crack at K{sub I} values considerably above 220 MPa(square root)m, the implicit limit of the ASME Code and the limit used in the IPTS studies. This document provides a discussion of the results of these experiments.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Biaxial Loading Effects on Fracture Toughness of Reactor Pressure Vessel Steel written by and published by . This book was released on 1995 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Warm Prestress Data written by GT. Embley and published by . This book was released on 1997 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Loading a cracked structure at elevated temperature, or warm prestressing (WPS), enhances its fracture resistance at a lower temperature. Five data sets, comprising 119 unclad pressure vessel steel specimens, were combined to derive correlations for WPS-enhanced fracture toughness (KIfrac) in the absence of ductile tearing. New WPS test results for 27 surface-flawed specimens, eight subclad-flawed specimens, and five strain-aged specimens are discussed. KIfrac exceeded non-WPS fracture toughness, KIc, for all experiments. The WPS data showed that no specimens failed while K was decreasing, and that at least an additional 7% additional reloading from the minimum value of applied KI took place prior to final fracture. The data included complete and partial unloading after WPS prior to final fracture. Crack tip three-dimensional elastic-plastic finite element (3DEPFE) analysis was performed to support statistical analysis of the data. Regression models were compared with the Chell WPS model.
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1974 with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:
