Development and Evaluation of Generic Test Pieces for Creep Property Assessment of Laser Powder Bed Fusion Components

Abstract

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 postprocessing 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 deg (perpendicular to build direction), 45 deg (diagonal) and 90 deg (parallel to build direction). Specimens extracted from the SEC are mechanically tested and compared to witness samples manufactured in 0 deg, 45 deg, and 90 deg 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 °C. Microstructural differences and hence differences in mechanical properties are found in extracted and witness samples.