After introducing the concepts and characteristics of welding thermal processes and weld pool behaviors, this book addresses essential advances in welding analysis and processes with an emphasis on the latest modeling and simulation methods. It covers techniques and formulas for assessing welding thermal processes, finite difference and finite analysis methods for calculating thermal conduction, and numerical simulation of weld pool behaviors in metal-inert-gas/metal-active-gas arc welding, It also covers keyhole and weld pool dynamics in plasma arc welding and vision-based sensing of weld pool shape and geometry. It also provides case studies of fluid flow and heat transfer in tungsten-inert-gas arc welding.

This book systematically describes the weld pool behavior in laser welding and its influencing factors from the perspectives of testing technology, theoretical calculation and process simulation technology, physical state transformation behavior of weld pools, and the impact of technical conditions on the weld pool behavior. The book covers extensive research achievements made in China in this field, some of which represent the latest cutting-edging researches conducted by the authors' research team. These latest research efforts mainly relate to the weld pool behavior of dual-beam laser welding, laser welding with filler wires, full-penetration laser welding of very-thick parts, and laser welding in vacuum and low vacuum conditions. The book is intended for undergraduate, graduate students and researchers who are interested in laser welding.

This book describes and systemizes analytical and numerical solutions for a broad range of instantaneous and continuous, stationary and moving, concentrated and distributed, 1D, 2D and 3D heat sources in semi-infinite bodies, thick plane layers, thin plates and cylinders under various boundary conditions. The analytical solutions were mainly obtained by the superimposing principle for various parts of the proposed 1D, 2D and 3D heat sources and based on the assumption that only heat conduction plays a major role in the thermal analysis of welds. Other complex effects of heat transfer in weld phenomena are incorporated in the solutions by means of various geometrical and energetic parameters of the heat source. The book is divided into 13 chapters. Chapter 1 briefly reviews various welding processes and the energy characteristics of welding heat sources, while Chapter 2 covers the main thermophysical properties of the most commonly used alloys. Chapter 3 describes the physical fundamentals of heat conduction during welding, and Chapter 4 introduces several useful methods for solving the problem of heat conduction in welding. Chapters 5 and 6 focus on the derivation of analytical solutions for many types of heat sources in semi-infinite bodies, thick plane layers, thin plates and cylinders under various boundary conditions. The heat sources can be instantaneous or continuous, stationary or moving, concentrated or distributed (1D, 2D or 3D). In Chapter 7 the temperature field under programmed heat input (pulsed power sources and weaving sources) is analyzed. In turn, Chapters 8 and 9 cover the thermal cycle, melting and solidification of the base metal. Heating and melting of filler metal are considered in Chapter 10. Chapter 11 addresses the formulation and solution of inverse heat conduction problems using zero-, first- and second-order algorithms, while Chapter 12 focuses on applying the solutions developed here to the optimization of welding conditions. In addition, case studies confirm the usefulness and feasibility of the respective solutions. Lastly, Chapter 13 demonstrates the prediction of local microstructure and mechanical properties of welded joint metals, while taking into account their thermal cycle. The book is intended for all researches, welding engineers, mechanical design engineers, research engineers and postgraduate students who deal with problems such as microstructure modeling of welds, analysis of the mechanical properties of welded metals, weldability, residual stresses and distortions, optimization of welding and allied processes (prewelding heating, cladding, thermal cutting, additive technologies, etc.). It also offers a useful reference guide for software engineers who are interested in writing application software for simulating welding processes, microstructure modeling, residual stress analysis of welds, and for robotic-welding control systems.

During welding, the composition, structure and properties of the welded structure are affected by the interaction of the heat source with the metal. The interaction affects the fluid flow, heat transfer and mass transfer in the weld pool, and the solidification behavior of the weld metal. In recent years, there has been a growing recognition of the importance of the weld pool transport processes and the solid state transformation reactions in determining the composition, structure and properties of the welded structure. The relation between the weld pool transport processes and the composition and structure is reviewed. Recent applications of various solidification theories to welding are examined to understand the special problems of weld metal solidification. The discussion is focussed on the important problems and issues related to weld pool transport phenomena and solidification. Resolution of these problems would be an important step towards a science based control of composition, structure and properties of the weld metal.

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.