Laves phase control of inconel 718 superalloy fabricated by laser direct energy deposition via δ aging and solution treatment

• Published in: Journal of materials research and technology Vol. 9; no. 5; pp. 9753 - 9765
• Main Authors: Liu, Fencheng, Lyu, Feiyue, Liu, Fenggang, Lin, Xin, Huang, Chunping
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-09-2020; Elsevier
• Subjects: Direct energy deposition; Inconel 718; Laves phase; Mechanical property; Solution treatment; δ phase; Inconel 718; Solution treatment; δ phase; Mechanical property; Direct energy deposition; Laves phase
• ISSN: 2238-7854
• DOI: 10.1016/j.jmrt.2020.06.061

In order to achieve the microstructure homogeneity at a lower temperature and improve the mechanical properties, a novel post heat treatment was introduced to Inconel 718 fabricated by laser direct energy deposition (LDED), by means of δ aging treatment + solution treatment. The microstructure analysis shows that the fully precipitation of δ phase in LDED Inconel 718 superalloy can “cut” the long strip Laves phase into small pieces. According with the δ phase solution treated at 1020 °C for 30 min, only tiny particle Laves phase was remained. The equilibrium volume fraction of Laves phase after δ phase solution treatment is about 1%, which is much lower than that of the as-deposited sample or the sample only solution treated at 1020 °C. Due to the solution strengthening and precipitation of γ″ phase during aging treatment, the tensile strength of δ aging + δ solution + double aging treated samples was 10.27% higher than that of directed solution + double aging treated samples, as well as a 31.38% and 52.71% increases in elongation and the reduction of area during tensile tests.