Heat treatment

Car components with doubled mechanical strength, higher fatigue resistance and improved energy absorption could be easily manufactured as the result of a new CSIRO heat treatment process for the high pressure die casting (HPDC) of aluminium.

'Our heat treatment methods offer major improvements in tensile mechanical properties and enhancement of a range of other material properties for HPDC components,' said CSIRO metallurgist Dr Roger Lumley.

'Components treated with the new process do not show surface blistering or dimensional changes, they retain an as-cast appearance.'

Surprisingly, fatigue resistance of aluminium HPDC components heat-treated with the new process can be as high as for some wrought aluminium products, tending towards limiting behaviour usually observed in steel.

The new procedures may also substantially raise energy absorption during fracture, which has significant implications for crash-sensitive structural components made by high pressure die-casting.

For example, one common secondary alloy almost doubles in energy absorption, when heat treated specifically for this purpose.