Tool geometries and process parameters required to friction stir weld high melting temperature materials

High melting temperature materials, including steels, stainless steels, and nickel base alloys, are used extensively in the oil and gas industry for structural components, tubular products and many other applications. The selection of a material for a given application is driven by the service and safety requirements. The service requirements for these materials are often severe, and demand the limits of mechanical and material properties. As these materials are fabricated into the finished application, they are often joined together by fusion welding in a variety of configurations. Because fusion welds reduce base metal properties, material selection is often based on weld properties. The friction stir welding (FSW) process produces a wrought microstructure and offers significant benefits in mechanical and corrosion properties over fusion welds. This paper presents polycrystallitic cubic boron nitride (PCBN) tool geometries and process parameters required to friction stir weld steels, stainless steels, and nickel base alloys.