Abstract
The fatigue behavior of friction stir processed (FSPed) cast aluminum alloy, AC4CH-T6 was investigated. FSP conditions were set to be the tool rotational speed of 500rpm and traveling speed of 200mm/min, in which strain late was relatively low. Plane bending fatigue tests have been performed using as-cast and FSPed specimens. Fatigue strengths of the FSPed specimens were highly improved compared with the as-cast ones. Casting defects were eliminated by FSP, resulting in higher fatigue limit. However, the crack growth rates of the FSPed specimens were faster than those of the as-cast ones due to softening of the material by heat input during FSP. The improvement of fatigue limit by FSP with low strain late was higher than that by FSP with high strain late. The effects of FSP with low stain rate were discussed based on the microstructural consideration.
