Creep data of Hastelloy X fabricated by laser powder bed fusion

The creep behavior of Hastelloy X fabricated by laser powder bed fusion was investigated, focusing on the testing temperatures of 700°C, 800°C, 900°C and 1000°C. Hastelloy X was selected as the first step because the Hastelloy X is a solid solution strengthened Ni-based alloy and a relatively simple material. For PiHA heat, the stress axis was parallel to the build direction, whereas for PiHC heat it was perpendicular. The creep strength of PiHA was similar to that of the conventional Hastelloy X at 700°C to 1000°C. The creep life of PiHC was one order of magnitude shorter than that of PiHA at 800°C and 900°C. For estimating allowable stress of additively manufactured Hastelloy X, the creep strength of PiHC will be minimum value. Therefore, the creep strength should be improved for PiHC to establish allowable stress comparable to the conventional Hastelloy X. The creep ductility was much lower in PiHA and PiHC than in the conventional Hastelloy X at all testing temperatures. No large difference in creep ductility was observed between PiHA and PiHC. Double local minimum values of creep rate were recognized in creep rate versus time curves at 700°C and 800°C for PiHA and PiHC. Creep voids and cracks were observed at grain boundaries perpendicular to the stress axis in PiHA and PiHC. M23C6, µ phase, R phase and M6C particles were observed after creep exposure.