Fusion welding is the main technological process applied in the production of weldments. Depending on the kind of applied heat source, the following fusion welding processes are distinguished: electric arc, electron beam, laser beam, electroslag, light beam, and gas welding. However, irrespective of the applied welding procedure, the main goal of any process is producing a sound welded joint. This is only possible with a sufficiently comprehensive allowance for the physicochemical processes. Presenting the latest research on the topic, Physical Chemistry of Fusion Welding is a cutting-edge and comprehensive book. The book contains modern representations of physicochemical processes that occur on the borders of contacting phases. Physical Chemistry of Fusion Welding presents this knowledge in a thorough and accessible manner, making it the ideal text for practical and scientific specialists in the fields of welding and metallurgy.