Influence of an additional heat treatment on the dimensional stability and the fatigue behaviour of die cast specimens made of the alloy AlSi9Cu3(Fe)Wednesday (08.11.2017) 17:00 - 17:20 Part of:
The use of high pressure die cast aluminium components in drive systems is increasing. In parallel to this, the operating temperatures in the drive systems are rising. Due to this heat impact submicroscopic structure changes take place, influencing the mechanical properties and the dimensional stability of die cast aluminium components. An appropriate heat treatment prior to operation can be performed to release these effects preventatively.
In this investigation high pressure die cast specimens made of the alloy AlSi9Cu3(Fe) are examined in view of dimensional stability and fatigue behaviour before and after heat treatment. The optimum heat treatment parameters have been specified based on quasi-static strength and ductility of the specimens. The dimensional stability and the fatigue behaviour of optimal heat treated specimens and of specimens in the initial state have been determined at room temperature and at 120 °C.
After the additional heat treatment the specimens showed a significantly higher dimensional stability. At fatigue loading the surface and cavities in the interior of the specimens are the dominant failure causes. In case of failure at cavities, a correlation could be established between the fatigue strength and the defect size based on a fracture mechanics approach. Despite increased quasi-static strength, the additionally heat treated specimens achieved a lower fatigue strength than the specimens in the initial state. The transferability of the gained results to parts could be proved by fatigue testing of a component.
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