Future trends in welding

When attempting to forecast future trends in welding technology, it is convenient to differentiate between traditional materials and advanced materials. The properties and functions of traditional materials are well known; therefore, improved performance can be best achieved by reducing the cost increasing the quality of the joining process and through automation and enhanced quality control procedures. The quality of the material depends on the industry considered. Welding structural aluminium is not new in the aerospace industry, yet, it is an advanced application in automotive production. The change to a spaceframe automobile design will remove the structural redundancy afforded by current designs; thus, new joining processes will be required to overcome the limited quality of resistance welding. Brazing as well as laser, or conventional arc welding processes are to handle the fabrication requirements of new automobile structural components. The cost of many advanced materials is so high, and their properties so specialized, that they will only be used where they are essential. Consequently, products will contain more joints, a greater number of which will join dissimilar materials. Few traditional joining processes are practical in this situation; new part designs and joining processes will be required. Adhesives can always be used, but joint properties often place severe limitations on part design or function. Brazing is considered, especially to join ceramics and metal-matrix composites. Low-temperature metallic bonding using transient liquid- phase technology will probably be extended to many more alloy systems. In the brazing process, a component of the brazing material or solder diffuses into the base material resulting in isothermal solidification of the filler material. For every new material developed, joining processes must be restudied or developed to use the material effectively. Use of new materials will be limited by the capability to exploit the joining processes, rather than by the ability to design or produce such materials. The present direction of improvement of welded structures is a decrease in their weight and energy requirement in fabrication, and improvement of consistency and endurance. High strength low-alloy (HSLA) steels are the Centre of application that widening the advances in this direction. The fabrication of structures from HSLA steels without preheating is one of the main problems in arc welding. The results of researches into the problem of hydrogen welded joints have been generalized. The main tendencies of the optimization of properties of HSLA steels are i) the decrease in the content of alloying elements, ii) an increase in the number of combinations of microalloying elements, iii) a decrease in the content of carbon, hydrogen, nitrogen, oxygen, residual elements, sulphur and phosphorus, iv) an improvement of the homogeneity and the level of mechanical properties and improvement of the formability, weldability and toughness of welded joints.