Investigation of Surface Roughness Effects on Additively Manufactured Metals Under Dynamic Loading
Abstract
The as-printed surfaces of parts produced through laser powder bed fusion are significantly rougher than surfaces produced through traditional manufacturing processes. This increased roughness can have a significant impact on mechanical properties, with perhaps the most notable detriment in the fatigue life of the part. Therefore, the as-printed surface roughness in additively manufactured materials must be studied more extensively to determine its impact on fatigue performance. This work investigates the surface roughness of additively manufactured specimens through the investigation of processing parameters and their effects on surface roughness in metal additive manufacturing. Furthermore, the relationships between as-printed surface roughness and fatigue behavior in AM materials are studied using both axial fatigue testing and vibration bending fatigue testing of nickel superalloy 718. Following the results of these initial tests, this work also examines the relationships between sharp corners and fatigue life in as-printed additively manufactured alloy 718. Results suggest that both rougher surfaces and sharp corner geometries cause decreases in fatigue life, thus providing guidelines for the design of additively manufactured components under fatigue loading conditions.
