Surface texture and high cycle fatigue of as-built metal additive AlSi7Mg0.6

The aluminium silicon alloy AlSi7Mg0.6 is gaining importance in additive manufacturing. This work is showing a correlation of surface quality and fatigue properties of three different AlSi7Mg0.6 as-built surfaces manufactured by laser powder bed fusion. All specimens were built in z-direction and the difference in surface quality was achieved by variation of the contour scanning parameters in the manufacturing process. Focus of the evaluation is on the reduced valley depth Svk rather than the commonly applied Ra (arithmetic mean of the line roughness profile) and Rt (maximum total height of the line roughness profile) and their areal equivalents Sa and Sz. Svk is derived from the material ratio curve and is a measure of the size of the valley population across the sample. It was found to show a better correlation with number of cycles to failure than parameters based on local extreme values such as Sz and Sv (depth of deepest detected valley).