Rolling-assisted direct energy deposited Inconel 718: Microstructural evolution and mechanical properties after optimized heat treatment

Post-heat treatment is a necessary and important step for additive-manufactured products to relieve residual stress and to further improve mechanical performance. In this work, the heat treatment strat-egy for Inconel 718 superalloy fabricated by rolling-assisted laser-directed energy deposition (L-DED) has been designed and systematically investigated for the first time. The results show that the designed ho-mogenization heat treatment at 1080 degrees C for 10 min can effectively dissolve most of the detrimental Lave phases existing in the rolling-assisted L-DED samples. Meanwhile, it results in a homogenous grain struc-ture through static recrystallization, while maintaining a similar prior-refined grain size of-8 mu m. On this basis, a high number density of gamma'' and gamma' precipitates appear in the microstructure after applying a subsequent double-aging heat treatment. The optimized microstructure through such effective post-heat treatment designed in this work has led to a significant increase in material strength at both the room and elevated temperatures while maintaining good ductility.(c) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.