Lightweight construction using aluminium has also become well established in aircraft and vehicle construction after new alloys opened up opportunities for new applications for a wide range of profiles and composite materials in recent years. For example, aluminium rail vehicles made by welding large profiles are up to 50 per cent lighter compared with conventional steel construction.
In lightweight construction, which is increasingly establishing itself in building construction, civil engineering and mechanical engineering, one constructs a plant in such a way that its weight is as small as possible while ensuring operating safety, service performance and economic efficiency. One achieves this by using lightweight materials and/or a material-saving design. Aluminium offers itself as a lightweight material thanks to its low specific weight of 2.7 grams per cubic centimetre (compared with 7.8 for steel). The other properties, especially the low modulus of elasticity, make it necessary to adopt a different type of design. One cannot merely take typical cross sections used in steel construction and modify the dimensions. Contact corrosion (see corrosion resistance) must be avoided. Of the many possible bonding and joining processes available, it is automatic riveting (punch riveting), clinching, welding and adhesive bonding are the ones that are mainly of interest.
Overall, lightweight construction using aluminium usually requires somewhat higher investments than lightweight steel construction. However, when one considers the whole utilisation period, this is compensated for many times over by lower maintenance costs thanks to the high corrosion resistance of aluminium and the energy savings resulting from its lower weight.