Corrosion behavior and mechanism of GH3535 alloy in NaOH, HF and H2O2 solution.

• Corrosion behavior of GH3535 in NaOH, HF and H 2 O 2 solution was studied firstly. • NaOH solution is chemically inert towards the GH3535. • GH3535 suffered pitting corrosion and intergranular corrosion in HF solution. • Oxidation and further reaction in HF solution accelerate the fall-off of carbides. • Fall-off of carbides cause the pitting corrosion of GH3535 in H 2 O 2 solution. Corrosion behaviors of GH3535 immersed in NaOH, HF and H 2 O 2 solutions were investigated at RT for 600 h. The micro-morphology of surface and cross section was systematically characterized by SEM, EDS, EPMA, XRD and Nano Indenter. GH3535 showed excellent corrosion resistance in NaOH solution, but suffered serious pitting corrosion and slight grain boundary corrosion in HF solution, whereas only distinct hole corrosion in H 2 O 2 solution due to the depletion of carbides. Element depletion, fall-off of carbides, decrease of hardness and Young's modulus of GH3535 were detected in HF and H 2 O 2 solution. However, NaOH solution is chemically inert towards GH3535. Corrosion mechanism was also explored based on the experimental measurement and thermodynamic calculation. Results not only provide the theoretical guidance for understanding the anticorrosion mechanism of GH3535 and purifying the molten salt, also expand the application of GH3535. [ABSTRACT FROM AUTHOR]