Improving Global Quality of Life

3.3 Welding and joining in sustainable growth and environment
The development of materials (metals and non-metals) is making enormous progress, with material 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.
12 Improving Global Quality of Life Through Optimum Use and Innovation of Welding and Joining Technologies