Microstructure, high-temperature cyclic oxidation, and hot corrosion behaviors of Inconel 718 alloy produced by laser-induction hybrid cladding

Abstract

<p>The microstructure evolution, cyclic oxidation, and hot corrosion behavior of the unheated-treated (As-built) and solution + double aging (SDA)-treated Inconel 718 alloys fabricated through laser-induction hybrid cladding (LIHC) were investigated. It was found that the as-built Inconel 718 alloy exhibits a columnar dendritic with intergranular Laves phase. After SDA-treated, γ", γ′, δ and carbide phases precipitated, the Laves phase became fine and dispersed. After cyclic oxidation, the Cr₂O₃ scales were formed on both as-built and SDA-treated LIHC-produced Inconel 718 alloy, which could provide good cyclic oxidation resistance for the Inconel 718 alloy. However, the as-built and SDA-treated LIHC-produced Inconel 718 alloy suffered severe hot corrosion in 95 wt% Na₂SO₄ + 5 wt% NaCl mixed salt solution and many corrosion products were generated, including Cr₂O₃, NiCr₂O₄, NaNbO₃, Na₂CrO₄, NiFe₂O₄, Fe₃O₄, and NiO. Nevertheless, the SDA-treated sample showed better cyclic oxidation and hot corrosion resistance than the as-built sample, owing to the more compact Cr₂O₃ scale.<br></p>