In-situ Quality Assurance for Electron-Based Additive Manufacturing by Electron Optical Observation

Well-established non-destructive testing methods in aero engine industry are time-consuming and expensive with a negative impact on economic viability, especially for parts from additive manufacturing. To improve the economics of electron beam powder bed fusion (PBF-EB), the detection and evaluation of backscattered electrons (BSEs) during the PBF-EB process is a highly promising approach. Electron optical (ELO) images are obtained using the electron beam in a way comparable with scanning electron microscopy. The method is capable of detecting defects (e.g., pores) and the part contour for each layer, thus providing information about the quality of the resulting component. The estimation of dimensional and geometrical accuracy is obtained from the comparison of design data (target geometry) with ELO data (actual geometry). The purpose of our investigation is the utilization of backscattered electron detection as a non-destructive in-situ testing method for additively manufactured aero engine parts of the second component class which includes turbine blades, fuel nozzles and casings.