Effect of powder characteristic on microstructure and mechanical property of additive manufacturing nickel-based superalloy IN718

Powder feedstocks have significant impacts on the performance of final parts processed by additive manufacturing (AM). In this work, the effects of particle size distributions (PSD) of powder and its preparation method on the microstructure and mechanical property of IN718 alloy prepared by laser powder bed fusion (LPBF) were systematically studied. The results show that when the powder size varies from 15 to 53 μm, the LPBF specimens built by powder with different PSD exhibit similar Laves phase content and local misorientation (LocMis) as well as the tensile property. Compared with that of gas atomized (GA) powder, the strength and elongation of LPBF specimen built by plasma rotating electrode processed (PREP) powder are apparently elevated. Better powder sphericity, less satellite powder and pores, and higher laser absorption rate of PREP powder favor to the improvement of the tensile property. The increasing yield strength (YS) of the LPBF specimen built by PREP powder is also closely related to higher relative density, Taylor factor and dislocation density. Although the precipitation strengthening effect is relatively weaker in the specimen built by PREP powder, stronger solid-solution strengthening, dislocation strengthening and grain boundary strengthening contribute to the its elevation of YS.