Post Processing of AM Parts to Increase Fatigue Strength and Durability of AM parts

The future of using additive manufactured parts in highly stressed aircraft components is limited due to the rough surface and abnormalities in the micro structure of AM parts. In addition, the continuous melting & solidification at the surface may produce undesirable residual tensile stress. Although improvements in powders and processing have increased the fatigue strength of AM components, testing still shows a 20% plus reduction when compared to parts made from forgings, plate or bar stock.

Post processing of AM using surface treatments like shot/laser peening and super finishing offer the designer improvement while producing almost no change to part geometry. Peening processes produce residual compressive stress that resist tensile stress from loading offering a fatigue benefit. Super finishing improves rough surface finishes and the corresponding stress concentrations that may lead to crack initiation.

Peening and super finishing used individually will enhance the properties of AM parts and using both processes offers additional enhancements to fatigue performance. We will present results of testing to demonstrate the benefits of post processing to enhance AM properties.