Sammendrag
An in-depth and integral understanding of the microstructural evolution during
thermomechanical process (TMP) is of great significance to optimize the
manufactural process for high-quality components via additive
manufacturing. The solidified microstructure model of Inconel 718 alloy
fabricated via laser powder bed fusion (L-PBF) is established by multiphase
field model firstly. Furthermore, the microstructural evolution during
homogenization process is simulated and optimized in this study. Phase field
simulation results show that the concentration gradient of Nb along the radius
of the cellular substructure decreases from the initial 1.217 wt% to 0.001 wt%,
and 67% area fraction of the Laves phase dissolves at the homogenization time
of 0.5 h, which have achieved the homogenization purpose. The experimental
results show that the average grain size decreases from 9.4 μm to 5.9 μm at the
homogenization time from 1.5 h (the standard AMS 5383) to 0.5 h, which
resulted in the increase of yield strength and tensile strength of the aged
alloy by 14% and 6%, respectively. This research can provide guidance and
reference for the microstructural control as well as the TMP parameters design
of the additive manufactured alloys.
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