Thermal cyclic fatigue analysis of three ...

The aluminum piston Al 11wt% Si alloys SC100, ACA8, A4032 were tested together with A2618-T6 concerning their mechanical properties and their thermal fatigue behavior. The alloy A2618 shows a better elongation to failure and higher yield stress compared to the other alloys by maintaining the low coefficient of thermal expansion (CTE). Thermal fatigue experiments confirmed that the Coffin-Manson equation can be used for life time prediction with the coefficients CP = 0.0385, KP = -0.377 comparable for A2618, while Kp =-0.45 for ACA8 and SC100 is obtained. The activation energy derived from the temperature dependence of life time was estimated as Q = 0.5eV as typical for aluminum alloys.