Download or read book The Influence of Warm Prestressing and Proof Loading on the Cleavage Fracture Toughness of Ferritic Steels written by Hamish Fowler and published by . This book was released on 1998 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 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:
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 Significant Issues in Proof Testing A Critical Appraisal written by G. G. Chell and published by . This book was released on 1994 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Significant Issues in Proof Testing written by and published by . This book was released on 1994 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Index to Theses with Abstracts Accepted for Higher Degrees by the Universities of Great Britain and Ireland and the Council for National Academic Awards written by and published by . This book was released on 1999 with total page 814 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Guidelines for Proof Test Analysis written by G. G. Chell and published by . This book was released on 1999 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Closer Look at Effects of the Loading Rate on Fracture Toughness in the Ductile to Brittle Transition Regime of a Ferritic Steel written by Hans-Jakob Schindler and published by . This book was released on 2015 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: An increased loading rate causes not only a shift of the ductile-to-brittle transition curve, but also a slight change of the shape of this curve. The latter tends to become steeper as the loading rate increases. This effect was observed even at loading rates that are considered to be quasi-static according to ASTM E1921-13: Standard Test Method for Determination of Reference Temperature, T0, for Ferritic Steels in the Transition Range, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2013. Actually, the coefficient 0.019 in the exponent of the MC turned out to be substantially higher at elevated loading rates. This means that a basic assumption of the evaluation procedure of ASTM E1921 is not met, which leads to an increased uncertainty of T0 or T0,x, respectively. This effect of is most pronounced in testing at elevated loading rates using the single-temperature option. An improved method to determine the reference temperature is proposed, where the exponent in the median transition curve in ASTM E1921 is considered to be an open parameter. The resulting reference temperatures, denoted as T100 andT100,x, respectively, are expected to be more accurate than standard T0, which is confirmed by comparison with experimental data. Furthermore, the validity requirements for T100 are less restrictive and more suitable than those in ASTM E1921, since they do not depend on the outcome of the tests. Based on the improved data, an improved estimation formula for the rate-induced shift of T0 is derived. Suggestions are made for improvement of ASTM E1921.
Download or read book British National Bibliography for Report Literature written by and published by . This book was released on 1999 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Influence of Long range Residual Stress on the Cleavage Fracture of Ferritic Steel written by Christopher John Aird and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Warm Prestressing on Fatigue Crack Growth Curves at Low Temperatures written by A. Bussiba and published by . This book was released on 1985 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low-temperature fatigue crack extension is studied in precracked single-edge-notched specimens of AISI 4340 steel. Steady-state crack extension in tension-tension fatigue and cyclic loading in conjunction with warm prestressing (WPS) are particularly emphasized. Effects of WPS on the fatigue crack growth curve are demonstrated and discussed. Special attention is given to the cleavage fracture mode, which dominates the features of the fatigue crack growth curve below the ductile-brittle transition (DBT) temperature. In AISI 4340 steel, which is characterized by DBT, WPS affects the alternative fracture mode and therefore alters the lower and upper bound values Kth and KIfc, respectively. For a more complete view, the behavior of AISI 304 stainless steel is discussed. The experimental results at low temperatures are mainly interpreted in terms of a transition in the cumulative crack tip damage process, induced by characteristic values of the stress intensity range amplitudes (?K).
Download or read book Predicting the Temperature and Strain Rate Dependences of the Cleavage Fracture Toughness of Ferritic Steels written by D. A. Curry and published by . This book was released on 1979 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Loading Mode on the Fracture Toughness of a Reduced Activation Ferritic martensitic Stainless Steel written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The critical J integrals of mode I (J[sub IC]), mixed-mode I/III (J[sub MC]), and mode III (J[sub IIIC]) were examined for a ferritic stainless steel (F-82H) at ambient temperature. A determination of J[sub MC] was made using modified compact-tension specimens. Different ratios of tension/shear stress were achieved by varying the principal axis of the crack plane between 0 and 55 degrees from the load line. The results showed that J[sub MC]s and tearing moduli (T[sub M]) varied with the crack angles and were lower than their mode I and mode III counterparts. Both the minimum J[sub MC] and T[sub M] occurred at a crack angle between 40 and 50 degrees, where [sigma][sub i]/[sigma][sub iii] was 1.2 to 0.84. The J[sub min] was 240 kJ/m[sup 2], and ratios of J[sub IC]/J[sub min] and J[sub IIIC]/J[sub min] were about 2.1 and 1.9, respectively. Morphology of fracture surfaces was consistent with the change of J[sub MC] and T[sub M] values. While the upper shelf-fracture toughness of F-82H depends on loading mode, the J[sub min] remains very high. Other important considerations include the effect of mixed-mode loading on the DBT temperature, and effects of hydrogen and irradiation on J[sub min].
Download or read book The Effect of Loading Rate and Temperature on the Fracture Toughness of High Strength Steels written by David P. Kendall and published by . This book was released on 1970 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effect of loading rates, ranging from 10 to 100,000 ksi square root of (in/sec), and temperatures, ranging from room temperature to -100F, on the plane strain fracture toughness of several high strength alloy steels has been determined. Materials investigated are a commercial 4340 steel, a modified 4330 steel from a gun tube forging having three different heat treatments and two different heats of 250 grade maraging steel. Test specimens utilized are essentially ASTM 'compact tension' type specimens of one inch thickness. Tests were conducted on an open loop, hydraulic, high loading rate tensile testing machine. Results are presented in the form of graphs of fracture toughness versus temperature for the maximum and minimum loading rates ('dynamic' and 'static'). Fracture toughness versus loading rate at -60F and yield strength versus elastic strain rate at room temperature, -60F and -100F for one heat of maraging steel are also reported. (Author).
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 Influence of Plastic Rate Sensitivity on Cleavage Fracture Initiation in Ferritic Steels written by and published by . This book was released on 2003 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:
