Inconel 718 Hybrid Laser-Based Directed Energy Deposition and Wrought Component Characterization through Small Punch Tests

Abstract

The combination of wrought materials and laser-based directed energy deposition (DED-LB) is being increasingly used for manufacturing new and repairing old or damaged components in several industries. Aerospace components made of Inconel 718 featuring small-thickness DED-LB buildups are a remarkable example of such a combination due to the high added value it brings. Despite that these are usually critical components, the miniature testing methods to assess the local mechanical properties in the buildup area are not fully developed. This work contributes to this miniature testing development with an improvement of the small punch testing (SPT) technique for measuring the mechanical properties of the weld line between the DED-LB and the wrought substrate. A new criterion for weld line positioning in the SPT specimens is proposed and applied on samples of hybrid wrought/DED-LB Inconel 718. The results of positioning the weld line at the necking site of the SPT specimen show that the proposed approach is valid for assessing the properties of the transition zone between the wrought and additive states. For the specific conditions tested and taking the wrought material as a reference, the strength of the Inconel 718 drops 10% in the weld line and 20% in the buildup.