The effect of interval pulsed laser deposition on the microstructure and mechanical properties of Inconel 718 parts using laser directed energy deposition

Abstract

The solidification process of laser directed energy deposition (LDED) affects elemental separation, microstructure, and tensile properties. This work proposes an interval pulsed laser deposition (IPLD) process to improve the cooling rate. The IPLD and continuous laser deposition (CLD) samples are prepared at the same laser power for comparative analysis. Solution treatment and aging (STA) heat treatment processes are developed to compare the as-deposited and STA samples. Finite element simulation results showed that the IPLD process has a smaller molten pool and a higher cooling rate. In the microstructure analysis, the IPLD samples have stronger [Formula: see text] texture and smaller grains in all samples. Smaller Laves phase distributions and Nb-rich areas are found in IPLD as-deposited samples. After the STA, the long-chain Laves phases completely dissolve into discrete areas and the Nb-rich areas almost disappear. More short rod and needle-like δ-phases are observed around small Laves phases, and the proportion of large-size Laves phases decreases significantly. The Nb mass fraction of Laves phases is 16.9 in IPLD samples, which is lower than 26.66 in CLD samples. For IPLD samples, the YS (1095 Mpa), UTS (1310 Mpa), and elongation (24.5%) reached the level of Inconel 718 wrought parts.

Keywords

• Laser directed energy deposition
• heat treatment
• Inconel 718
• interval pulsed laser deposition
• microstructure
• tensile properties