Cyclic plasticity at pores and inclusions in cast Al–Si alloys

Finite element analyses of micronotches including pores and silicon particles of an A356 aluminum alloy were performed to elucidate microstructure–property relations for fatigue crack incubation. Several important findings resulted. By varying the particle and pore size, spacing, aspect ratio, and clustering, the relative microstructural differences were quantified related to micronotch root cyclic plasticity. Results from realistic two-dimensional microstructures showed that minimal microstructure-scale cyclic plasticity corresponds well to the measured fatigue strength at 107 cycles for low porosity A356 aluminum alloy specimens. “Realistic” and idealized particles/pores simulations were used to formulate a local Coffin–Manson type law for crack incubation.