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Author : Shantikumar Vasudevan Nair
Publisher :
ISBN 13 :
Total Pages : 314 pages
Book Rating : 4.:/5 (799 download)
Download or read book Hydrogen Assisted Subcritical Crack Growth and Crack-tip Plasticity written by Shantikumar Vasudevan Nair and published by . This book was released on 1983 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 25 pages
Book Rating : 4.:/5 (227 download)
Download or read book Critical Issues in Hydrogen Assisted Cracking of Structural Alloys written by and published by . This book was released on 2006 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Both internal and hydrogen environment assisted cracking continue to seriously limit high performance structural alloys and confound quantitative component prognosis. While intergranular H cracking assisted by impurity segregation can be minimized, other mechanisms promote IG cracking and transgranular H cracking modes have emerged; new alloys suffer serious H cracking similar to old materials. Micromechanical models of crack tip H localization and damage by decohesion predict important trends in threshold and subcritical crack growth rate behaviour. H diffusion appears to limit rates of cracking for monotonic and cyclic loading; however, uncertain%adjustable parameters hinder model effectiveness. It is necessary to better define conditions within 0.1-5 micronmeter of the crack tip, where dislocations and microstructure dominate continuum mechanics, and chemistry is localized. Nano-mechanics modeling and experimental results show very high levels of H accumulated in the crack tip fracture process zone, as necessary for interface decohesion. Contributing mechanisms include high crack tip stresses due to dislocation processes such as strain gradient plasticity, as well as powerful H production and trapping proximate to the electrochemically reacting crack tip surface. New sub- micrometer resolution probes of crack tip damage will better define features such as crack path crystallography (EBSD + Stereology) and surface morphology (high brightness, dual detector SEM), local H concentration (%IDS and NRA), and validate crack tip mechanics modelling (micro-Laue x-ray diffraction and EBSD).
Author : Shou Hui Chen
Publisher :
ISBN 13 :
Total Pages : 518 pages
Book Rating : 4.:/5 (319 download)
Download or read book Anisotropic Plasticity Associated with Subcritical Slow Crack Growth in Single Crystals written by Shou Hui Chen and published by . This book was released on 1990 with total page 518 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Emilio Martínez Pañeda
Publisher : Springer
ISBN 13 : 3319633848
Total Pages : 166 pages
Book Rating : 4.3/5 (196 download)
Download or read book Strain Gradient Plasticity-Based Modeling of Damage and Fracture written by Emilio Martínez Pañeda and published by Springer. This book was released on 2017-08-23 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive introduction to numerical modeling of size effects in metal plasticity. The main classes of strain gradient plasticity formulations are described and efficiently implemented in the context of the finite element method. A robust numerical framework is presented and employed to investigate the role of strain gradients on structural integrity assessment. The results obtained reveal the need of incorporating the influence on geometrically necessary dislocations in the modeling of various damage mechanisms. Large gradients of plastic strain increase dislocation density, promoting strain hardening and elevating crack tip stresses. This stress elevation is quantified under both infinitesimal and finite deformation theories, rationalizing the experimental observation of cleavage fracture in the presence of significant plastic flow. Gradient-enhanced modeling of crack growth resistance, hydrogen diffusion and environmentally assisted cracking highlighted the relevance of an appropriate characterization of the mechanical response at the small scales involved in crack tip deformation. Particularly promising predictions are attained in the field of hydrogen embrittlement. The research has been conducted at the Universities of Cambridge, Oviedo, Luxembourg, and the Technical University of Denmark, in a collaborative effort to understand, model and optimize the mechanical response of engineering materials.
Author : Victor Raymond Sawicki
Publisher :
ISBN 13 :
Total Pages : 246 pages
Book Rating : 4.E/5 ( download)
Download or read book Hydrogen Induced Cracking in a High Strength Steel written by Victor Raymond Sawicki and published by . This book was released on 1971 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Nilesh Raykar
Publisher :
ISBN 13 :
Total Pages : 336 pages
Book Rating : 4.:/5 (11 download)
Download or read book Modelling of Hydrogen Assisted Stress Corrosion Cracking written by Nilesh Raykar and published by . This book was released on 2013 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modelling of hydrogen assisted stress corrosion cracking (HASCC) within the framework of mechanics is very important for its control and avoidance. The main focus of this study is to develop suitable approach for modelling and analysis of stable crack growth through high strength steels under HASCC. A new strategy based on combined analytical/numerical solution and finite element based cohesive zone model (CZM) has been developed. This has helped to couple analysis of hydrogen diffusion and crack growth during HASCC. The strategy has been applied to study crack growth in compact tension (CT) specimens. The solution to diffusion process is obtained through either an analytical or a numerical solution to the governing differential equation. The crack growth is analysed by CZM. For the analytical solution, both one- and two-dimensional approximations of the domain have been considered. The new CZM strategy, termed as hydrogen concentration dependent cohesive zone model (HCD-CZM), has been used for both CT and circumferentially notched tensile (CNT) round specimens. The CNT specimen has been employed for the first time to obtain the fracture toughness data of high strength steel under internal and external supply of hydrogen. The experimental scheme involving CNT specimen under slow strain rate loading is demonstrated as a valid experimental procedure for study of HASCC for high strength steels. Both types of HASCC, internal hydrogen assisted cracking (IHAC) and hydrogen environment assisted cracking (HEAC), are found to induce a proportionate drop in fracture toughness under higher hydrogen concentration near the crack tip. The experimentally obtained lowest fracture toughness data compare favourably with lower range of published threshold values for the similar material. The experimental average crack growth rates too agree with the reported data for the material. For CT specimens, both schemes of analysis of diffusion, excluding or including the effect of hydrostatic stress and plastic strain, predict variation of crack opening displacement with crack growth with good accuracy. Diffusion solution based on one- and two-dimensional analyses do not significantly alter the prediction of crack growth. The effect of hydrostatic stress on the distribution of hydrogen concentration is observed to be significant as long as plastic strain is less than 5%. The study has given rise to an important correlation between hydrogen concentration dependent strength reduction and plastic strain rate. A new modelling technique is presented for the CNT specimen with eccentrically placed ligament using two-dimensional finite element approximations; this has considerably simplified analysis of the problem which otherwise would require a three-dimensional solution. For CNT specimens, the HCD-CZM approach employing both analytical and finite difference based diffusion solutions predicted the critical fracture toughness in agreement with experimental results. In this case too, the inclusion of hydrostatic stress in the diffusion analysis has been found to have not so significant influence on the prediction of experimental observations. The K-resistance curve obtained for the case is included. The proposed HCD-CZM has been found to satisfactorily handle variation in specimen geometry, material and source of hydrogen supply. The thesis is divided into six chapters dealing sequentially with introduction, literature review, experiments with CNT specimen, analysis of CT specimens, modelling of CNT specimens and conclusions.
Author : M. Gao
Publisher :
ISBN 13 :
Total Pages : 48 pages
Book Rating : 4.:/5 (227 download)
Download or read book Crack Paths and Hydrogen-Assisted Crack Growth Response in AISI 4340 Steel written by M. Gao and published by . This book was released on 1983 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study of the correlation and crack growth response was undertaken to better define the elemental processes involved in gaseous hydrogen embrittlement. AISI 4340 steel fracture under sustained load in hydrogen and in hydrogen sulfide over a range of temperatures and pressures, whose crack growth kinetics have been well characterized previously, was chosen for study. Fractographic results showed that crack growth followed predominantly along prior-austenite grain boundaries, with a small amount of quasi-cleavage, at low temperatures. At high temperatures, crack growth occurred primarily by microvoid coalescence. The fracture surface morphology, which is indicative of the micromechanisms for crack growth, was essentially the same for hydrogen and hydrogen sulfide. Changes in fracture morphology, i.e., crack paths, corresponded to changes in crack growth kinetics, both of which depended on pressure and temperature. There was no evidence for crack nucleation in advance of the main crack, and this suggests that the fracture process zone is located within one prior-austenite grain diameter from the crack tip.
Author : Jia-Hong Huang
Publisher :
ISBN 13 :
Total Pages : 316 pages
Book Rating : 4.:/5 (214 download)
Download or read book Internal Hydrogen-induced Subcritical Crack Growth in Stainless Steels written by Jia-Hong Huang and published by . This book was released on 1989 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three types of stainless steel--austenitic, ferritic and duplex--were cathodically precharged with hydrogen at high temperature in a molten salt electrolyte. Constant strain rate tests and sustained load tests were performed in air at temperatures from 0 to 50$spcirc$C with hydrogen contents up to 41 wt. ppm. The electrical potential drop method with optical calibration was used to monitor the crack growth position, continuously. The log(da/dt) vs. K curves had definite thresholds for subcritical crack growth (SCG), but the stages II and III were not always clearly delineated. In the unstable austenitic steel the threshold decreased with increasing hydrogen content or increasing temperature, but beyond about 15 wt. ppm the stage II became less distinct. In the stable stainless steel, SCG was observed on a specimen containing 41 wt. ppm hydrogen. In the duplex alloy, the second stage of cracking was highly K-dependent and the crack growth behavior was more sensitive to bulk hydrogen content than to temperature. In the ferritic alloy, SCG at 25$spcirc$C was observed on a specimen precharged with 2.2 wt. ppm hydrogen. Fractographic features were correlated to stress intensity, hydrogen content and temperature. In the unstable austenitic steel, more interface fracture occurred at low temperature and high hydrogen content, while more microvoid coalescence (MVC) occurred at low hydrogen content. In the duplex alloy, a flat fracture surface with narrow tear ridges was observed for specimens containing above 8 wt. ppm hydrogen. In the ferritic alloy, specimens tested in air fractured by MVC in contrast to those tested in 108 kPa hydrogen, which showed intergranular and transgranular facets on fracture surfaces. The interpretation of the phenomena is based on: the different hydrogen diffusivity and solubility in ferrite and austenite, stress-induced phase transformation, and outgassing from the crack tip. Comparing the SCG behavior of internal hydrogen with that of external hydrogen, it is found that external hydrogen is more damaging than internal hydrogen. This is probably because the critical hydrogen concentration for SCG must be reached at a location that is very near the crack tip.
Author : V. Kharin
Publisher :
ISBN 13 :
Total Pages : 19 pages
Book Rating : 4.:/5 (125 download)
Download or read book Role of Fatigue Crack Closure Stresses in Hydrogen-Assisted Cracking written by V. Kharin and published by . This book was released on 1999 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Crack closure effects on hydrogen-assisted cracking (HAC) were studied in terms of the influence of residual stresses produced by load removals at fatigue cycling on stress-assisted hydrogen diffusion towards rupture sites in the crack tip zone. The finite element procedure was applied to cyclic load elastoplastic large-deformation analysis combined with stress-assisted diffusion. Small-scale yielding near the crack tip was addressed and characterized in terms of the stress intensity factor (SIF). The elastoplastic situation near the tip of a blunting-closing crack revealed the cyclically stable stress evolution established after a couple of loading cycles (but this was not attained for strains). Crack closure effects were negligible for sustained-load HAC at SIF above the maximum value at precracking. The test duration for reliable evaluation of the threshold SIF for HAC was estimated. Crack closure affects near-tip hydrogen diffusion, and consequently HAC, at dynamic rising loading after precracking. Modeling was performed for the range of SIF increase rates. It showed that a premature fulfillment of the local fracture criterion in terms of critical combination of the hydrogen concentration and stress-strain parameters can occur at slow dynamic loading if compared with the sustained-load case. The dominating factor--stress or strain--and the "scale" of the local rupture event are of decisive importance for this. The performed simulations provide more insight into the items of conservatism of HAC testing data and the sources of their uncertainty.
Author : Lothar Wagner
Publisher : John Wiley & Sons
ISBN 13 : 3527606947
Total Pages : 584 pages
Book Rating : 4.5/5 (276 download)
Download or read book Shot Peening written by Lothar Wagner and published by John Wiley & Sons. This book was released on 2006-05-12 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shot peening has been proved to be a powerful instrument in enhancing the resistance of materials to various kinds of stress-induced damage, particularly against damage due to cyclic loading (fatigue) in air or in aggressive environments. As shot peening can be used for a wide variety of structural components irrespective of shape and dimensions, the number of shot peening applications in many industrial branches is increasing. The use of peen forming as a technique to form large metal parts into complicated shapes is also increasing, particularly in the aerospace industry. The Conference covers all aspects of the Science, Technology and Application of Shot Peening, and was intended to attract users, manufacturers as well as scientists working in the field of "Materials Treatment by Shot Peening". Emphasis was put on the current state of knowledge and research. This book offers scientists and engineers an unique opportunity to update their knowledge on shot peening.
Author : Grosvenor Cook Story (III.)
Publisher :
ISBN 13 :
Total Pages : 432 pages
Book Rating : 4.:/5 (14 download)
Download or read book Hydrogen Assisted Cracking of a Low Alloy Steel-pressure, Temperature and Yield Strength Effects on the Threshold Fracture Toughness written by Grosvenor Cook Story (III.) and published by . This book was released on 1980 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Ian Milne
Publisher : Elsevier
ISBN 13 : 0080490735
Total Pages : 4647 pages
Book Rating : 4.0/5 (84 download)
Download or read book Comprehensive Structural Integrity written by Ian Milne and published by Elsevier. This book was released on 2003-07-25 with total page 4647 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this major reference work is to provide a first point of entry to the literature for the researchers in any field relating to structural integrity in the form of a definitive research/reference tool which links the various sub-disciplines that comprise the whole of structural integrity. Special emphasis will be given to the interaction between mechanics and materials and structural integrity applications. Because of the interdisciplinary and applied nature of the work, it will be of interest to mechanical engineers and materials scientists from both academic and industrial backgrounds including bioengineering, interface engineering and nanotechnology. The scope of this work encompasses, but is not restricted to: fracture mechanics, fatigue, creep, materials, dynamics, environmental degradation, numerical methods, failure mechanisms and damage mechanics, interfacial fracture and nano-technology, structural analysis, surface behaviour and heart valves. The structures under consideration include: pressure vessels and piping, off-shore structures, gas installations and pipelines, chemical plants, aircraft, railways, bridges, plates and shells, electronic circuits, interfaces, nanotechnology, artificial organs, biomaterial prostheses, cast structures, mining... and more. Case studies will form an integral part of the work.
Author : Thomas Allen Adler
Publisher :
ISBN 13 :
Total Pages : 428 pages
Book Rating : 4.:/5 (758 download)
Download or read book Hydrogen Assisted Crack Growth in Mild Steels written by Thomas Allen Adler and published by . This book was released on 1980 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : T. P. Groeneveld
Publisher :
ISBN 13 :
Total Pages : 28 pages
Book Rating : 4.:/5 (772 download)
Download or read book Hydrogen-assisted Crack Growth in 2-1/4 Cr-1 Mo Steel written by T. P. Groeneveld and published by . This book was released on 1978 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Robert O. Ritchie
Publisher : Elsevier
ISBN 13 : 0323902790
Total Pages : 168 pages
Book Rating : 4.3/5 (239 download)
Download or read book Introduction to Fracture Mechanics written by Robert O. Ritchie and published by Elsevier. This book was released on 2021-05-27 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Fracture Mechanics presents an introduction to the origins, formulation and application of fracture mechanics for the design, safe operation and life prediction in structural materials and components. The book introduces and informs the reader on how fracture mechanics works and how it is so different from other forms of analysis that are used to characterize mechanical properties. Chapters cover foundational topics and the use of linear-elastic fracture mechanics, involving both K-based characterizing parameter and G-based energy approaches, and how to characterize the fracture toughness of materials under plane-strain and non plane-strain conditions using the notion of crack-resistance or R-curves. Other sections cover far more complex nonlinear-elastic fracture mechanics based on the use of the J-integral and the crack-tip opening displacement. These topics largely involve continuum mechanics descriptions of crack initiation, slow crack growth, eventual instability by overload fracture, and subcritical cracking. Presents how, for a given material, a fracture toughness value can be measured on a small laboratory sample and then used directly to predict the failure (by fracture, fatigue, creep, etc.) of a much larger structure in service Covers the rudiments of fracture mechanics from the perspective of the philosophy underlying the few principles and the many assumptions that form the basis of the discipline Provides readers with a "working knowledge" of fracture mechanics, describing its potency for damage-tolerant design, for preventing failures through appropriate life-prediction strategies, and for quantitative failure analysis (fracture diagnostics)
Author : N. Ohtsuka
Publisher :
ISBN 13 :
Total Pages : 20 pages
Book Rating : 4.:/5 (125 download)
Download or read book Characteristics of Hydrogen-Assisted Cracking Measured by the Holding-Load and Fractographic Method written by N. Ohtsuka and published by . This book was released on 1990 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The holding-load and fractographic (HLF) test method has been proposed by the authors to measure the threshold stress intensity KIH or KIscc and the crack growth rate in a hydrogen or corrosive environment. In this paper, the HLF method was used to measure KIH for five different heats of ASME SA387 Grade 22, Class 2 steel, and the effect of the hydrogen, material, and loading conditions on KIH were examined. The diffusive behavior of hydrogen in the test materials and the modes of fracture due to hydrogen-assisted cracking (HAC) were also investigated. KIH, obtained by the HLF method, showed just a little dependence on the tensile strength and was considerably lower than the existing literature data for relatively low-strength steels. The fracture toughness KCH of one of the materials in the environment was measured by the HLF test and the modified JIc test. Although KIH was shown to be very low, KCH was nearly equal to KIc, the plane-strain fracture toughness in a neutral environment, and it was considered not to have been lowered by the hydrogen environment.
Author : Richard P Gangloff
Publisher : Elsevier
ISBN 13 : 0857093894
Total Pages : 864 pages
Book Rating : 4.8/5 (57 download)
Download or read book Gaseous Hydrogen Embrittlement of Materials in Energy Technologies written by Richard P Gangloff and published by Elsevier. This book was released on 2012-01-16 with total page 864 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many modern energy systems are reliant on the production, transportation, storage, and use of gaseous hydrogen. The safety, durability, performance and economic operation of these systems is challenged by operating-cycle dependent degradation by hydrogen of otherwise high performance materials. This important two-volume work provides a comprehensive and authoritative overview of the latest research into managing hydrogen embrittlement in energy technologies.Volume 1 is divided into three parts, the first of which provides an overview of the hydrogen embrittlement problem in specific technologies including petrochemical refining, automotive hydrogen tanks, nuclear waste disposal and power systems, and H2 storage and distribution facilities. Part two then examines modern methods of characterization and analysis of hydrogen damage and part three focuses on the hydrogen degradation of various alloy classesWith its distinguished editors and international team of expert contributors, Volume 1 of Gaseous hydrogen embrittlement of materials in energy technologies is an invaluable reference tool for engineers, designers, materials scientists, and solid mechanicians working with safety-critical components fabricated from high performance materials required to operate in severe environments based on hydrogen. Impacted technologies include aerospace, petrochemical refining, gas transmission, power generation and transportation. Summarises the wealth of recent research on understanding and dealing with the safety, durability, performance and economic operation of using gaseous hydrogen at high pressure Reviews how hydrogen embrittlement affects particular sectors such as the petrochemicals, automotive and nuclear industries Discusses how hydrogen embrittlement can be characterised and its effects on particular alloy classes
