Areal fatigue strength assessment of cast aluminium surface layers

The fatigue strength of cast aluminium surface layers is significantly affected by casting imperfections. Experimental work reveals crack initiation due to three failure modes; microporosity, cast surface texture as well as a combination of both. A novel local sub-area evaluation of notch factors for surface texture characterisation utilises areal surface texture by pit depth values Svlocal, ranging within several hundred microns, and related notch root radii ρ‾ distributions. Additionally, the cast bulk strength is calculated by Murakami's approach. For all three failure cases, the presented holistic fatigue layer strength assessment methodology is well applicable for sand cast aluminium.