Influence of build orientation on the creep behavior of IN738LC manufactured with laser powder bed fusion

Abstract

While metal Laser Powder Bed Fusion (PBF-LB/M) offers many advantages, such as increased design freedom, it is yet to be accepted as a reliable manufacturing route. Due to the highly oriented solidification of the PBF-LB/M process, the microstructural anisotropy significantly affects mechanical short- and long-term properties. Component build orientation directly influences grain morphology and orientation and thus mechanical properties.In this study, IN738LC creep samples are manufactured in three build orientations (0°, 45° and 90°) using PBF-LB/M. Creep tests are carried out at 750 °C and 850 °C with applied stresses up to 350 MPa. While the results of 90° and 0° agree with the creep results of other Ni-superalloys manufactured with PBF-LB/M, where the 90° specimen achieves the longest time to rupture and largest creep strain, the 45° specimen shows differing creep results compared to other Ni-superalloys with the least time to fracture. This study discusses the correlation between microstructure and build direction and their effect on creep behavior, especially on the 45° specimen.