IIW White Paper

3.3 Welding and joining in sustainable growth and environment Thedevelopment ofmaterials (metals andnon-metals) ismakingenormous progress,withmaterial properties being optimised in areas such as higher strength, higher toughness, longer temperature resistance, good corrosion resistance as well as the ability for economically viable recycling and harmless final disposal. For the product under consideration, the designer has the possibility of selecting the material that is optimally appropriate for the stresses in each case depending on its specific weight. If suitable joining processes are available, the designer can combine these materials in such a way that the material, which is optimally appropriate for the stresses in each case, is used at every location on the product. This results in the so-called “ multi-material design ” but has its limits, on the one hand, in the technical feasibility and, on the other hand, in the economic viability. Such a combination of different and dissimilar materials is only possible, however, with suitable and reliable joining technologies. New ones are supplementing the established technologies and processes. In particular, ever more significance has been attached to the so-called hybrid processes in recent years. These are the combination of joining processes, e.g. adhesive bonding with resistance welding or mechanical joining in automobile construction or the combination of gas-shielded arc welding with laser welding in shipbuilding and other sectors. Friction stir welding which, in current practice, is only economically viable to use on components made of aluminium or its alloys, non-vacuum electron beam welding which may possibly compete with laser welding in individual applications and refinements in laser technology (e.g. fibre lasers) for welding are examples of new processes. The increased sensitivity of the materials to heat input by the welding must, however, also be taken into account. As a result of modern possibilities in electronics, energy input into the component via the arc or the material supply can be controlled in such a way that, even in the low-power short-circuiting arc, the metal is transferred from the electrode to the material in a spatter-free and nevertheless reliable process. Today, some very different materials can also be joined with each other in a material-locking form, e.g. aluminium with steel by means of arc brazing or laser riveting, steel with nickel-base alloys by means of pulsed-arc welding or copper with aluminium. There is not yet any optimum joining technology, however, for many other material combinations conceivable today. Lap joints, for example, which are necessary for riveting, bolting or adhesive bonding, do not lead to the optimum force flow and need additional material in the joint, which often conflicts with the desired weight reduction. On the other hand, these joints have an additional safety potential due to the crack arresting capacity in the joint. 3.4 Value and benefits of welding Welding and joining are not only important economic factors during manufacturing of technical products. Often the only possible way to manufacture large parts is by applying welding or allied processes as these parts cannot be manufactured in one piece, or various materials must be used in one part in order to guarantee the service capability of the product. Other areas of economic interest are the manufacturers of products utilised during welding and joining ( such as equipment, machines and filler materials), and for the necessary weld tests, and also the service providers which qualify the required personnel. Figure 3.1 shows the macroeconomic effect in the form of the value added in the European market 1 for these goods and services. The global market can be assessed

1 Belgium, Bulgaria, Denmark, Germany, Estonia, Finland, France, Greece, United Kingdom incl. Northern Ireland, Ireland, Italy, Croatia, Latvia, Lithuania, Luxemburg, Netherlands, Norway, Austria, Poland, Portugal, Romania, Sweden, Switzerland, Slovakia, Spain, Czech Republic, Hungary.

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Through Optimum Use and Innovation of Welding and Joining Technologies

Improving Global Quality of Life