Welding is traditionally divided into Welding processes and Welding metallurgy and in several academic institutions one of these branches dominates the research. For a producer of welded products, it is the combination of these two areas which is important. Consequently, the research within the welding arena covers both welding processes and welding metallurgy. The purpose is to do research on issues of interest to large parts of the welding industry. Therefore, we work on the welding process, which are those most common in industry, like gas metal arc welding, plasma welding, laser welding and friction stir welding. Within welding metallurgy there is an extensive activity, involving both high strength steel, duplex and super duplex steel stainless steels, aluminium and nickel-based super alloys. The studies include both weldability, corrosion and mechanical properties, especially fatigue properties. Another area of importance for welding is heat treatment. Heat treatment is often a part of a complete welding procedure and there are also many similarities between welding and heat treatment when it comes to effects on the material microstructure and properties.