1.3 Machining properties
WARNING: This page is about a different car, the 2013 BMW 550i GT, 2012 BMW 550i GT, 2011 BMW 550i GT, and 2010 BMW 550i GT. However, it is still accessible from the selected car via links, so may be relevant.
| Properties of aluminum compared with steel | Effects |
|---|---|
| Aluminum parts are magnetically neutral. | Attachment with magnetic tools/working aids is not possible. |
| Elasticity is only 1/3 as high. | Convertibility is limited in comparison with steel. |
| Elongation failure is approx. 50% slighter. | Overstretching the material results in strain-hardening and an increased tendency of cracking. |
| Electrical conductivity is almost 4 times higher. | Electric welding procedures require different equipment (MIG welding). |
| Material expansion during heating is twice as high. | The material expands more markedly. Shorter heat treatment is necessary for removing dents. |
| Thermal conductivity is 3 times higher. | Heat is drained more quickly. Adjoining working areas are affected more heavily e.g. during welding. |
| Microstructural change between 200°C and 250° C. | Elongation characteristics and thus plasticity are improved. Strength is reduced.
IMPORTANT:
No heat treatment when working on the vehicle structure! Temperature cannot be monitored to sufficiently exact levels in garages.
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| Aluminum shows no annealing colors. | The melting point is 650°C. Once the melting temperature has been reached, the material begins to flow without any further indications. The temperature can only be estimated by means of the paint coloring and the surface warpage.
IMPORTANT:
Do not use thermal applicators. Not suitable for garage use because the paint runs too quickly.
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