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<p>In this paper, the effect of heat treatment schemes on the microstructural evolution and mechanical properties of Inconel 718 (IN718) alloy fabricated by Laser-Based Powder Bed Fusion (PBF-LB) has been investigated. The microstructure of the as-built sample exhibits characteristic columnar grains and chain-like Laves phases, which degrade the mechanical properties of IN718 alloy. During heat treatment, these Laves phases dissolve gradually, and the released Nb atoms promote the precipitation of δ, γ′, and γ″ phases. The fractions of residual Laves and δ phases decrease significantly with increasing heat treatment temperature. Concurrently, recrystallization in the heat-treated samples occurs, becoming complete above 1080 °C. The complete recrystallization leads to grain coarsening and the formation of high-angle grain boundaries (HAGBs). The sample homogenization-treated at 1150 °C (HA1150) develops a strain-free microstructure. Both microhardness and tensile strength of IN718 samples demonstrate a parabolic trend, initially increasing and then decreasing with higher heat treatment temperatures. The balance between strength and ductility can thus be tailored by controlling the volume fraction of strengthening phases and the grain size. Consequently, the SA1080 sample exhibits the optimum combination of properties, achieving a tensile strength of 1436 MPa and an elongation of 12.9%, which are superior to those of wrought IN718 alloy.</p>

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Effects of heat treatment on microstructure and mechanical properties of Inconel 718 alloy prepared by PBF-LB

  • 期刊论文

  • 发表日期：

    2026年1月19日

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  • Tian Chen,
  • Wenjie Wu,
  • Daoyuan Li,
  • Haichao Li,
  • Ke Han,
  • Wanting Sun

摘要

In this paper, the effect of heat treatment schemes on the microstructural evolution and mechanical properties of Inconel 718 (IN718) alloy fabricated by Laser-Based Powder Bed Fusion (PBF-LB) has been investigated. The microstructure of the as-built sample exhibits characteristic columnar grains and chain-like Laves phases, which degrade the mechanical properties of IN718 alloy. During heat treatment, these Laves phases dissolve gradually, and the released Nb atoms promote the precipitation of δ, γ′, and γ″ phases. The fractions of residual Laves and δ phases decrease significantly with increasing heat treatment temperature. Concurrently, recrystallization in the heat-treated samples occurs, becoming complete above 1080 °C. The complete recrystallization leads to grain coarsening and the formation of high-angle grain boundaries (HAGBs). The sample homogenization-treated at 1150 °C (HA1150) develops a strain-free microstructure. Both microhardness and tensile strength of IN718 samples demonstrate a parabolic trend, initially increasing and then decreasing with higher heat treatment temperatures. The balance between strength and ductility can thus be tailored by controlling the volume fraction of strengthening phases and the grain size. Consequently, the SA1080 sample exhibits the optimum combination of properties, achieving a tensile strength of 1436 MPa and an elongation of 12.9%, which are superior to those of wrought IN718 alloy.