Building height-related creep properties of Inconel 718 superalloy fabricated by laser powder bed fusion

Abstract

The building height-dependent creep properties and microstructures of laser powder bed fusion-fabricated Inconel 718 superalloy were investigated. Creep specimens taken from the as-fabricated plate component at different building heights were tested along the building direction at 650 °C. The results show that under the same heat treatment condition, the recrystallization degree of the specimens taken from the bottom, middle and top of the Inconel 718 plate component differs widely due to the differences in the dislocation density and the texture intensity along the building direction. The bottom specimen exhibited a high recrystallization degree and thus had the longest creep life. Such excellent creep properties of the bottom specimen are mainly attributed to the lower dislocation density and the higher Taylor factor, which cause the lower creep rate, and the lower grain boundary volume fraction, thus reducing the void nucleation sites. The present findings reveal that the impact of the building height-dependent creep performance on the overall service reliability should be considered comprehensively in the subsequent geometrical design of the laser powder bed fusion-fabricated complex structural components.