Structure and properties of LW 4280, a new high γ′ Ni-based superalloy fabricated by laser powder bed fusion

Abstract

This study presents the successful development of a new high γ′ nickel-based superalloy, LW 4280, using laser powder bed fusion. Microstructural analysis revealed the absence of γ′ precipitates in the as-built condition. A designed sub-solvus heat treatment resulted in a bimodal distribution of γ′ precipitates. The heat-treated specimens displayed yield strength of 1038, 904, 690, 500, 333, 264, and 169 MPa, the ultimate tensile strength of 1455, 1055, 807, 621, 424, 329 and 205 MPa, and elongation of 26%, 26%, 17%, 13%, 24%, 19% and 30% at 21, 760, 871, 927, 982, 1038, and 1065 ⁰C, respectively. Stress rupture tests on heat-treated specimens displayed good rupture characteristics, with rupture times of 190, 205, and 42 h at 871, 927, and 981 °C for stresses of 276, 152, and 138 MPa, respectively. A fractographic analysis was conducted on both the tensile and stress-ruptured specimens to comprehend the failure mechanism.