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

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, gamma", gamma ' , delta and carbide phases precipitated, the Laves phase became fine and dispersed. After cyclic oxidation, the Cr2O3 2 O 3 scales were formed on both as-built and SDA-treated LIHCproduced 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 2 SO 4 + 5 wt% NaCl mixed salt solution and many corrosion products were generated, including Cr2O3, 2 O 3 , NiCr2O4, 2 O 4 , NaNbO3, 3 , Na2CrO4, 2 CrO 4 , NiFe2O4, 2 O 4 , Fe3O4, 3 O 4 , 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 2 O 3 scale.