Laser powder bed fusion of a new high gamma prime Ni-based superalloy with improved weldability

This study reports the crack-free fabrication of a new high gamma prime precipitation hardened Ni-based superalloy by Laser Powder Bed Fusion (LPBF) process. In the as-built condition, scanning electron microscopy and electron backscattered diffraction analysis indicated the presence of elongated columnar grains with an orientation along (1 0 0) direction. Following the sub-solvus heat treatment cycle determined using Thermo-Calc software, crack-free microstructure with columnar grains was observed along (1 0 0) orientation. High-resolution scanning electron microscope analysis revealed a bimodal distribution of gamma prime precipitates and a uniform distribution of carbide precipitates in the heat treated samples. As a result of heat treatment, hardness increased from 365 HV to 508 HV. The heat treated samples also displayed excellent yield strength, ultimate tensile strength, and elongation of 939 MPa, 1368 MPa, and 23% respectively at room temperature. Mechanical testing at elevated temperatures confirmed the yield strength, tensile strength, and elongation reached 80 MPa, 106 MPa, and 34% respectively at 1121 degrees C. The stress rupture test of the heat-treated samples revealed good creep properties with rupture times of 559 h and 75 h, respectively, at 927 degrees C and 982 degrees C, for stresses of 152 MPa and 138 MPa. (c) 2021 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study demonstrates the crack-free fabrication of a new high gamma prime precipitation hardened Ni-based superalloy using LPBF process. Heat treatment significantly improved hardness and mechanical properties, with excellent performance at elevated temperatures. The samples exhibited good creep properties under stress rupture test.