Effect of pressure cycles and thermal conditions on the reliability of a high-pressure diecast Al alloy heating radiator
Giulio Timelli, Alessandro De Mori, Reza Haghayeghi
The fatigue reliability of a diecast AlSi11Cu2(Fe) alloy radiator has been investigated at different pressure amplitudes and thermal exposure. Based on failure mode analysis, two failure mechanisms are observed during fatigue testing, i.e. leakage at the interface between the diecast element and the plug, and fatigue fracture of a radiator element.
Fatigue life tests have been carried out at two different pressure amplitudes, 3 and 4 MPa, and two holding temperatures, 40 and 60 °C, respectively. The results reveal how the main cause of failure is related to the fatigue failure of a radiator element in the whole heating system. This is due to casting defects such as gas porosity and oxides which are formed during the filling phase of the die cavity in high-pressure die casting. Furthermore, casting defects increase the leakage failure and reduce the fatigue life of the radiator. An increase of the holding temperature increases the frequency of leakage failure of radiators.
Cumulative probability plot of fatigue life distributions for heating radiators tested at 40 and 60 °C.
Laboratory testing machine used to evaluate the fatigue life of heating radiators.
Thermal images referred to the surfaces of (a) fixed and (b) moveable dies after the casting was ejected and before the spraying phase.
Major conclusions
- The main cause of failure is related to the fatigue failure of a radiator element in the heating system.
- An increase of the holding temperature increases the frequency of leakage failures.
- Casting defects such as gas porosity and oxide bi-films increase the leakage failure and reduce the fatigue life of the radiator.
