The hot corrosion of 310 stainless steel with pre-coated NaCl/Na2SO4 mixtures at 750 °C

The high-temperature corrosion behavior of 310 stainless steel has been studied at 750 °C in air with 2 mg cm−2 mixtures of various NaCl/Na2SO4 ratios. The corrosion behavior and morphological development were investigated by weight gain kinetics, metallographs, depths of attack, metal losses, and X-ray analyses. The results show that weight gain kinetics in simple oxidation reveals a steady-state parabolic rate law after 3 h, while the kinetics with salt deposits display multi-stage growth rates. NaCl is the main corrosive specie in high-temperature corrosion involving mixtures of NaCl/Na2SO4 and is responsible for the formation of internal attack. The most severe corrosion takes place with the 75% NaCl mixtures. Uniform internal attack is the typical morphology of NaCl-induced hot corrosion, while the extent of intergranular attack is more pronounced as the content of Na2SO4 in the mixture is increased.