The Welding and Brazing of the Refractory Metals Niobium, Tantalum, Molybdenum and Tungsten - a Review*

This review covers the present and future problems in the development and welding of niobium, tantalum, molybdenum and tungsten and their alloys. Their metallurgical characteristics are discussed together with the influence of impurities and alloying elements on mechanical properties, alloy development and weldability. Other factors briefly discussed are availability, high temperature strength, ductility and oxidation resistance. The general problems which will be met when welding these materials are described together with means of assessing weld quality. Information on the welding and brazing of each material and its alloysis assessed in order to define lines of research. Most reported work has been carried out in the United States and the outline research programme is drawn up as a basis for work in the United Kingdom. It is the opinion of the authors that a welding research programme must be included as an integral part of the development of refractory metal alloys.