Development and evaluation of generic test pieces for creep property assessment of laser powder bed fusion components

Metal Laser Powder Bed Fusion (PBF-LB/M) allows for high degrees of design freedom and the manufacture of high temperature Ni-based materials, such as IN738LC. The PBF-LB/M microstructure is dependent on several factors, including process parameters, component geometry, build orientation and post-processing steps (e.g. heat treatment). The correlation between the resulting microstructure and these parameters is material specific and not yet fully understood. In this study, the development of a Specimen Extraction Cube (SEC), based on a generic component with design aspects related to turbomachinery applications, is presented. The SEC allows for the extraction of three samples, one for each of the build orientations: 0 degrees (perpendicular to build direction), 45 degrees (diagonal) and 90 degrees (parallel to build direction). Specimens extracted from the SEC are mechanically tested and compared to witness samples manufactured in 0 degrees, 45 degrees and 90 degrees build orientation. Particular focus is placed on correlating measured properties and their variations with heat treated microstructures. Creep testing was performed using 240 MPa and a temperature of 850 degrees C. Microstructural differences and hence differences in mechanical properties are found in extracted and witness samples.