Control of Welding Distortion in Thin-Plate Fabrication


Book Description

The intense temperature fields caused by heat sources in welding frequently lead to distortions and residual stresses in the finished product. Welding distortion is a particular problem in fabricating thin plate structures such as ships. Based on pioneering research by the authors, Control of Welding Distortion in Thin-Plate Fabrication reviews distortion test results from trials and shows how outcomes can be modeled computationally. The book provides readers with an understanding of distortion influences and the means to develop distortion-reducing strategies. The book is structured as an integrated treatment. It opens by reviewing the development of computational welding mechanics approaches to distortion. Following chapters describe the industrial context of stiffened plate fabrication and further chapters provide overviews of distortion mechanics and the modeling approach. A chapter on full-scale welding trials is followed by three chapters that develop modeling strategies through thermal process and thermo-mechanical simulations, based on finite-element analysis. Simplified models are a particular feature of these chapters. A final sequence of chapters explores the simulation of welding distortion in butt welding of thin plates and fillet welding of stiffened plate structures, and shows how these models can be used to optimize design and fabrication methods to control distortion. Control of Welding Distortion in Thin-Plate Fabrication is a comprehensive resource for metal fabricators, engineering companies, welders and welding companies, and practicing engineers and academics with an interest in welding mechanics. - Allows practitioners in the field to minimize distortion during the welding of thin plates - Provides computational tools that can give insight into the effects of welding and fabrication procedures - Demonstrates how welding distortion in thin plate fabrications can be minimized through design







Processes and mechanisms of welding residual stress and distortion


Book Description

As a fabrication technology, welding presents a number of technical challenges to the designer, manufacturer, and end-user of the welded structures. Both weld residual stress and distortion can significantly impair the performance and reliability of the welded structures. They must be properly dealt with during design, fabrication, and in-service use of the welded structures. There have been many significant and exciting developments on the subject in the past ten to fifteen years. Measurement techniques have been improved significantly. More importantly, the development of computational welding mechanics methods has been phenomenal. The progresses in the last decade or so have not only greatly expanded our fundamental understanding of the processes and mechanisms of residual stress and distortion during welding, but also have provided powerful tools to quantitatively determine the detailed residual stress and distortion information for a given welded structure. New techniques for effective residual stress and distortion mitigations and controls have also been applied in different industry sectors. Processes and Mechanisms of Welding Residual Stress and Distortion provides a comprehensive summary on the developments in the subject. It outlines theoretical treatments on heat transfer, solid mechanics and materials behavior that are essential for understanding and determining the welding residual stress and distortion. The approaches for computational methods and analysis methodology are described so that non specialists can follow them. There are chapters devoted to the discussion of various techniques for control and mitigation of residual stress and distortion, and residual stress and distortion results for various typical welded structures are provided. The second half of the book looks at case studies and practical solutions and provides insights into the techniques, challenges, limitations and future trends of each application. This book will not only be useful for advanced analysis of the subject, but also provide sufficient examples and practical solutions for welding engineers. With a panel of leading experts this authoritative book will be a valuable resource for welding engineers and designers as well as academics working in the fields of structural and mechanical engineering.




Analysis of Welded Structures


Book Description

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. Then, this text considers residual stresses, heat flow, distortion, fracture toughness, and brittle and fatigue fractures of weldments. This selection concludes by discussing the effects of distortion and residual stresses on buckling strength of welded structures and effects of weld defects on service behavior. 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.




Minimization of Welding Distortion and Buckling


Book Description

Welding is a cost-effective and flexible method of fabricating large structures, but drawbacks such as residual stress, distortion and buckling must be overcome in order to optimize structural performance. Minimization of welding distortion and buckling provides a systematic overview of the methods of minimizing distortion and buckling in welded structures.Following an introductory chapter, part one focuses on understanding welding stress and distortion, with chapters on such topics as computational welding mechanics, modelling the effect of phase transformations on welding stress and distortion and using computationally efficient reduced-solution methods to understand welding distortion. Part two covers different methods of minimizing welding distortion. Chapters discuss methods such as differential heating for minimizing distortion in welded stiffeners, dynamic thermal tensioning, reverse-side heating and ways of minimizing buckling such as weld cooling and hybrid laser arc welding.With its distinguished editor and international team of contributors, Minimization of welding distortion and buckling is an essential reference for all welders and engineers involved in fabrication of metal end-products, as well as those in industry and academia with a research interest in the area. - Provides a systematic overview of the methods of minimizing distortion and buckling in welded structures - Focuses on understanding welding stress and distortion featuring computational welding mechanics and modelling the effect of phase transformations - Explores different methods of minimizing welding distortion discussing differential heating and dynamic thermal tensioning




Distortion Control


Book Description

Identifies different types of distortion of welded materials and describes techniques to be used to control and eliminate the distortion.




Welding Deformation and Residual Stress Prevention


Book Description

Generally, welding produces welding deformation and residual stress in the products, which influences the quality and performance of the products. Although many engineers and researchers have made great effort how to control these incidents, they have still remained unresolved. Welding Deformation and Residual Stress Prevention provides a unique computational approach to the prediction of the effects of deformation and residual stress on materials. The goal is to provide engineers and designers with the ability to create their own computational system for predicting and possibly avoiding the problem altogether. - The basic theories including "theory of elastic-plastic analysis" and "inherent strain theory" , and analysis procedures are described using a simple three-bar model - Online simulation software to perform basic analysis on welding mechanics - Examples of strategic methods and procedures are illustrated to have solved various welding-related problems encountered in the process of construction - Appendices present data bases for welding residual stresses, temperature dependent material properties, etc.




Ship Construction and Welding


Book Description

This book addresses various aspects of ship construction, from ship types and construction materials, to welding technologies and accuracy control. The contents of the book are logically organized and divided into twenty-one chapters. The book covers structural arrangement with longitudinal and transverse framing systems based on the service load, and explains basic structural elements like hatch side girders, hatch end beams, stringers, etc. along with structural subassemblies like floors, bulkheads, inner bottom, decks and shells. It presents in detail double bottom construction, wing tanks & duct keels, fore & aft end structures, etc., together with necessary illustrations. The midship sections of various ship types are introduced, together with structural continuity and alignment in ship structures. With regard to construction materials, the book discusses steel, aluminum alloys and fiber reinforced composites. Various methods of steel material preparation are discussed, and plate cutting and forming of plates and sections are explained. The concept of line heating for plate bending is introduced.Welding power source characteristics, metal transfer mechanisms, welding parameters and their effects on the fusion zone, weld deposit, and weld bead profile are discussed in detail. Various fusion welding methods, MMAW, GMAW, SAW, Electroslag welding and Electrogas welding and single side welding are explained in detail. Friction stir welding as one of the key methods of solid state welding as applied to aluminum alloys is also addressed. The mechanisms of residual stress formation and distortion are explained in connection with stiffened panel fabrication, with an emphasis on weld induced buckling of thin panels. Further, the basic principles of distortion prevention, in-process distortion control and mitigation techniques like heat sinking, thermo-mechanical tensioning etc. are dealt with in detail. In its final section, the book describes in detail various types of weld defects that are likely to occur, together with their causes and remedial measures. The nondestructive testing methods that are most relevant to ship construction are explained. Lastly, a chapter on accuracy control based on statistical principles is included, addressing the need for a suitable mechanism to gauge the ranges of variations so that one can quantitatively target the end product accuracy.




Hybrid Laser-Arc Welding


Book Description

Hybrid laser-arc welding (HLAW) is a combination of laser welding with arc welding that overcomes many of the shortfalls of both processes. This important book gives a comprehensive account of hybrid laser-arc welding technology and applications.The first part of the book reviews the characteristics of the process, including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality. Part two discusses applications of the process to such metals as magnesium alloys, aluminium and steel as well as the use of hybrid laser-arc welding in such sectors as ship building and the automotive industry.With its distinguished editor and international team of contributors, Hybrid laser-arc welding is a valuable source of reference for all those using this important welding technology. - Reviews arc and laser welding including both advantages and disadvantages of the hybrid laser-arc approach - Explores the characteristics of the process including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality - Examines applications of the process including magnesium alloys, aluminium and steel with specific focus on applications in the shipbuilding and automotive industries