Effects of homogenization temperature on creep performance of laser powder bed fusion-fabricated Inconel 718 at 650?

The effect of homogenization temperature (1000 ?, 1100 ? and 1200 ?) on creep performance of laser powder bed fusion-fabricated Inconel 718 at 650 ? was investigated utilizing the small punch creep test method and the small punch creep specimens loaded perpendicular to the building direction, which can well reflect the comprehensive performance of the specimen in all radial directions of the circular plane parallel to the building direction. The results show that the specimen homogenized at 1100? for 1 h followed by double-aging treatment exhibited better creep performance than the other two ones homogenized at 1000 ? and 1200?. Such enhancement of the creep performance is attributed to fewer crack initiation sites, the higher GB sliding rate near the precipitates at grain boundaries to release stress concentrations, the higher strengthening effect of gamma & PRIME;& PRIME; phases in grains, and the more effective resistance to cracking by the special GBs than the other specimens. The basic mechanism for the small punch creep of laser powder bed fusion-fabricated Inconel 718 at 650 ? was elucidated by the careful characterization of the microstructures and theoretical calculations. A feasible ho-mogenization strategy for further improving the SPC performance of laser powder bed fusion-fabricated Inconel 718 alloy is to make the specimen have fewer and smaller granular precipitates at GBs, and more tortuous GBs by introducing more special GBs with considering the grain size. Such a key point can be used to determine the appropriate subsequent heat treatment for laser powder bed fusion thin-walled Inconel 718 component.