Author: John G. Papp
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Alexander Robert Troiano
Publisher: ASM International
ISBN: 9781615031788
Category : Technology & Engineering
Languages : en
Pages : 356

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Author: Ellis E. Fletcher
Publisher:
ISBN:
Category : Metals
Languages : en
Pages : 28

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High-strength steels are susceptible to delayed cracking under suitable conditions. Frequently such a brittle failure occurs at a stress that is only a fraction of the nominal yield strength. Considerable controversy exists over whether such failures result from two separate and distinct phenomena or whether there is but one mechanism called by two different names. Stress-corrosion cracking is the process in which a crack propagates, at least partially, by the stress induced corrosion of a susceptible metal at the advancing tip of the stress-corrosion crack. There is considerable evidence that this cracking results from the electrtrochemical corrosion of a metal subjected to tensile stresses, either residual or externally applied. Hydrogen-stress cracking is cracking which occurs as the result of hydrogen in the metal lattice in combination with tensile stresses. Hydrogen-stress cracking cannot occur if hydrogen is prevented from entering the steel, or if hydrogen that has entered during processing or service is removed before permanent damage has occurred. It is generally agreed that corrosion plays no part in the actual fracture mechanism. This report was prepared to point out wherein the two fracture mechanisms under consideration are similar and wherein they differ. From the evidence available today, the present authors have concluded that there are two distinct mechansims of delayed failure. (Author).

Author: A. W. Thompson
Publisher:
ISBN:
Category :
Languages : en
Pages : 38

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The objective of this program has been to understand the stress corrosion cracking (SCC) behavior of high-strength aluminum alloys, and in particular to understand the role played by hydrogen embrittlement in such cracking. The approach taken was to study microstructural effects on both hydrogen embrittlement and SCC, and to establish, insofar as possible, microstructural and fractographic correlations with cracking behavior, and detailed understanding of the mechanical behavior of hydrogen-charged material. When this program began, there existed only a single unconfirmed report of hydrogen embrittlement in a high-strength aluminum alloy. That report was confirmed (on 7075-T651), and extensive additional evidence acquired (on 7075, 2124 and 7050, in a variety of heat treatments), permitting us to assemble a complete and detailed description of hydrogen embrittlement and its dependence on microstructure in Al alloys, in some 14 publications. A parallel effort on SCC behavior has also been conducted, using the technique of Mode I - Mode III testing to provide information on the relative contributions of hydrogen embrittlement and anodic dissolution to SCC. The Mode I data for 7075 showed a close parallel to the hydrogen charging results, in microconstructural dependence and in fractography. The Mode III data showed that the anodic dissolution component of SCC is small compared to hydrogen embrittlement, and moreover, has a much weaker dependence on microstructure. (Author).

Author: Benjamin Floyd Brown
Publisher:
ISBN:
Category : Aluminum alloys
Languages : en
Pages : 388

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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 956

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Author: C. S. Kortovich
Publisher:
ISBN:
Category :
Languages : en
Pages : 33

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The purpose of the study was to compare the known behavior of hydrogen embrittled high-strength steel to the characteristics of environmentally-induced stress corrosion failure where hydrogen is continuously generated at the specimen surface. The incubation time for the initiation of slow crack growth was accelerated by prestressing for a fixed time below the lower critical limit. These results obtained on high-strength steel in a stress corrosion environment were directly comparable to behavior of hydrogenated specimens. These data along with hydrogen diffusivity measurements and the insensitivity of the incubation time and crack growth rate to specimen thickness indicated that the stress corrosion process was controlled by the distilled water-metal surface reaction. (Author).

Author: J. C. Scully
Publisher:
ISBN:
Category : Alloys
Languages : en
Pages : 494

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Author: Richard A. Oriani
Publisher: William Andrew
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 920

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Author: William Donald Needham
Publisher:
ISBN:
Category : Naval architecture
Languages : en
Pages : 554

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An experimental study was conducted to evaluate the corrosion performance of weldments of a high strength low alloy(HSLA) steel in a simulated seawater environment. This steel, designated HSLA80, was developed by the United States Navy for use in ship structural applications. Stress corrosion CRACKING(SCC) and hydrogen embrittlement(HEM) were investigated by conducting 42 Wedge-Opening load(WOL) tests as a function of stress intensity and corrosion potential and 33 Slow Strain Rate(SSR) tests as a function of strain rate and corrosion potential. The corrosion potentials were chosen to simulate the environmental conditions of free corrosion, cathodic protection and hydrogen generation. The results from this investigation indicated that HSLA 80 base metal and weldments were susceptible to hydrogen assisted cracking(HAC) in a seawater environment under conditions of continuous plastic deformation and triaxial stress in the presence of hydrogen. The heat-affected zone of the weldment was found to be the most susceptible portion of the weld joint. A lower bound was established for the critical stress intensity for stress corrosion cracking for HSLA 80 base metal and weldments.(Theses).