Differences of the high-temperature corrosion of ferrite steel T92 caused by applied stresses and NaCl–Na₂SO₄ molten salts

The corrosion behavior of T92 in the environment characterized by the applied stress and NaCl–Na₂SO₄ molten salts was studied by scanning electron microscope and energy dispersion spectroscopy. The dissolution and precipitation of oxides in molten salts resulted in changes in the elemental distribution in corrosion scales. Moreover, the applied stress was found to accelerate the outward diffusion of Cr causing fast deformation of protective oxides because of the easy diffusion path available. On the contrary, applied stresses also compacted the corrosion layers and enlarge the gaps between layers. These two opposite effects indicate that there should be a threshold stress for corrosion relief.