A new method to study the corrosion behavior in chloride salts and its effects on tensile properties

A novel experimental approach was developed in this study to decouple and quantitatively assess the individual effects of thermal aging and molten salt corrosion on the mechanical properties of GH3535 alloy. Two groups of experiments and three distinct specimen conditions-original, thermally aged, and molten salt corroded-were systematically designed. The corrosion experiments were conducted in NaCl-KCl-MgCl₂ eutectic salt at 700 °C for 400 h under an inert argon atmosphere. Microstructural analyses revealed that thermal aging induced the precipitation of fine M₆C carbides at grain boundaries without altering the primary blocky carbides or grain size. In contrast, molten salt corrosion produced a distinct two-layered cross-sectional morphology: an outer region composed of NiO, MgCr 2 O 4 , and MgMoO 4 , and an inner Cr-depleted region resulting from selective Cr dissolution. Tensile testing at room temperature and 700 °C showed that thermal aging increased the yield strength (YS) and ultimate tensile strength (UTS) due to grain boundary strengthening, while significantly reducing elongation (EL). Molten salt corrosion further decreased UTS and EL due to surface damage, yet YS remained higher than that of the original alloy, attributed to carbide-induced strengthening that counteracted defect-induced weakening. A key innovation of this study is the isolation and comparative quantification of thermal and chemical degradation mechanisms, providing new insights into the long-term mechanical performance of GH3535 alloy in high-temperature chloride salt environments relevant to next-generation energy systems. • The corrosion behavior and tensile property of GH3535 alloy in NaCl-KCl-MgCl 2 were firstly studied. • Thermal aging precipitated grain boundary phases, increasing strength but reducing elongation. • Molten salt corrosion caused surface defects, reducing the strength and elongation.