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Author: K.G. Richards
ISBN13: 978-0853000587
Title: Brittle Fracture of Welded Structures
Format: txt mbr azw lit
ePUB size: 1173 kb
FB2 size: 1446 kb
DJVU size: 1224 kb
Language: English
Publisher: British Welding Research Association; First Edition edition (September 1971)
Pages: 24

Brittle Fracture of Welded Structures by K.G. Richards

Are you sure you want to remove Brittle fracture of welded structures from your list? Brittle fracture of welded structures. Published 1971 by Welding Institute in Cambridge . Written in English. Brittleness, Fatigue, Structural Steel, Welding. 22 p. Number of pages.

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To prevent brittle fracture in welded structures, it is necessary to use steels and electrodes which are suitable to their service conditions and to adopt suitable welding conditions or heat input. In general, a notch is needed for the initiation of brittle fracture. Practically, weld cracks or defects are found as the notches along the bond or in the weld metal. Mean-while, accompanying the automation of welding, heat input has been increasing from a viewpoint of im-proving productivity.

Part 1 concentrates on analyzing fracture of welded joints and structures, with chapters on constraint-based fracture mechanics for predicting joint failure, fracture assessment methods and the use of fracture mechanics in the fatigue analysis of welded joints. In part 2, the emphasis shifts to fatigue, and chapters focus on a variety of aspects of fatigue analysis including assessment of local stresses in welded joints, fatigue design rules for welded structures, k-nodes for offshore structures and modeling residual stresses in predicting the service life of structures. All conclusions derive from testing and analysis performed on ductile materials – it is not presently known if similar conclusions can be drawn for brittle materials. Further experimental validation and numerical modelling is required.

Explains in general terms what a brittle fracture is, the conditions under which it may occur, and what can be done to avoid it. Publisher Information.

A brittle fracture in a metal is a result of crack propagation across crystallographic planes and is frequently associated with little plastic deformation. The propagation of a cleavage crack, as it is known, requires much less energy than does a ductile crack and can occur at an applied stress much lower than that at which failure would normally be expected. The phenomenon is particularly associated with welded fabrications because the energy required to propagate a brittle fracture is low. This means that the stress required to start the crack can be supplied just by the residual stresses from welding without the necessity of an externally applied stress. Furthermore welding can damage the fracture toughness of the steel and in the past some weld metals had very poor fracture toughness.

Fracture of welded structures has been a spectacular though rare part of the engineering scene in the latter half of the century. Unfortunately the most susceptible structures, such as bridges, ships, storage tanks and pressure vessels, are those whose failure results in serious loss of life and property. This fact justifies the effort expended in understanding and preventing fracture of such structures.

Analysis of Welded Structures: Residual Stresses, Distortion, and their Consequences encompasses several topics related to design and fabrication of welded structures, particularly residual stresses and distortion, as well as their consequences. This book first introduces the subject by presenting the advantages and disadvantages of welded structures, as well as the historical overview of the topic and predicted trends. This book also provides supplementary discussions on some related and selected subjects. This text will be invaluable to metallurgists, welders, and students of metallurgy and welding. 10. Theoretical and Experimental Studies of the Brittle Fracture of Welded Structures. 11. The Fatigue Fracture of Weldments as it Relates to Residual Stress. 12. The Role of Residual Stress in Stress Corrosion Cracking and Hydrogen Embrittlement.

General prcb lem of brittle fracture in welded structures. service temperature, material toughness, design, welding: residual stresses, fatigue, constraint, etc. ) can contribute to brittle frac-tures in large welded structures such as ship hulls 5 ‘y. However, the recent development of fracture mechanicsl ‘-20) has shown that there are three primary factors that. stresses from welding may be. present. All three of these factors must be present for a brittle fracture to occur in structures. A1l other factors such as temperature, loading rate, re-sidual stresses, etc. merely affeet the above three primary factors

Brittle crack-arrest fracture toughness (KIa) was determined as a function of the temperature in a large-scale (1 x 1 m) 50-mm thick steel base metal and its high heat-input (32 kJ/mm) weld. An impact initiates crack propagation from a notch at low temperature toward a higher temperature region where the crack stopped due to the improved fracture toughness. The relationship between the toughness and crack-arrest temperature provides the KIa at −10 °C of about 100 MPa√m in the weld specimen, which is a significant decrease compared to that of the base metal (240 MPa√m)