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

摘要

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 ofδaging treatment?+?solution treatment. The microstructure analysis shows that the fully precipitation ofδphase in LDED Inconel 718 superalloy can “cut” the long strip Laves phase into small pieces. According with theδphase solution treated at 1020?°C for 30?min, only tiny particle Laves phase was remained. The equilibrium volume fraction of Laves phase afterδphase 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 ofδaging?+?δsolution?+?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.