Microstructure and mechanical properties of Ni-based alloys fabricated by laser powder bed fusion

Microstructure and mechanical properties of Ni-based alloys fabricated by laser powder bed fusion The Advanced Materials and Manufacturing Technologies (AMMT) program is aiming at the accelerated incorporation of new materials and manufacturing technologies into nuclear-related systems. Complex Ni-based components fabricated by laser powder bed fusion (LPBF) could enable operating temperatures at T > 700¡C in aggressive environments such as molten salts. However, mechanical properties data relevant to material qualification is very limited, even for Ni-based alloys routinely fabricated by LPBF such as IN718 (Ni-19Cr-18Fe-5Nb-3Mo), IN625 (Ni-22Cr-9Mo-3Nb) and Haynes 282 (Ni-20Cr-10Co-8.5Mo-2.1Ti-1.5Al). Creep data was therefore generated on LPBF 718 and LPBF 282, and the measured creep strength was similar to the creep strength of wrought counterparts. The heat treatments had, however, to be tailored to the LPBF-specific microstructure to achieve grain recrystallization and form the strengthening gammaÕ and/or gammaÕÕ precipitates. In addition, in-situ data generated during printing and ex-situ computed tomography scans were used to correlate the creep properties to the defect distribution. Finally, optimization of the LPBF printing parameters was achieved for two additional Ni-based alloys of interest for nuclear applications, IN617 (Ni-22Cr-13Co-9Mo) and Haynes 230 (Ni-22Cr-14W-2Mo). Based on these results, opportunities for LPBF Ni-based components in current and next generation nuclear reactors will be discussed.