Damage Accumulation During High Temperature Testing of a Squeeze Formed Aluminum Piston Alloy

The effect of time dependent damage on elevated temperature fatigue performance has been investigated for a squeeze formed aluminum-silicon piston alloy. From the results of elevated temperature fatigue, creep and dwell tests carried out, it has been shown that creep damage has little effect at short lives but at longer lives leads to a reduction in fatigue life. It is perceived that although this damage does not directly cause the initiation of a fatigue crack, the overall resistance of the material to damage is reduced. The observed micromechanisms are related to those observed in engine tested components and the use of damage mechanisms to predict lifetimes explored. It has been shown that linear damage accumulation based on creep and fatigue mechanisms may be used to produce a first estimate of life in the materials tests.