Corrosion of Fe-17%Cr Steels in (Na2SO4+NaCl) Salts at 800 and 900℃

Stainless steel grade 430 with a composition of Fe-17%Cr was corroded in $Na_2SO_4$ and ($Na_2SO_4+NaCl$) salts at 800 and at $900^{\circ}C$ for up to 20 h. It corroded mainly to $Cr_2O_3$, along with a small amount of $Fe_2O_3$ and $Fe_3O_4$. The formed oxide scales were neither dense nor compact enough owing to their ensuing dissolution into the salt during corrosion, which facilitated internal corrosion. Corrosion occurred faster at $900^{\circ}C$ than $800^{\circ}C$. NaCl in $Na_2SO_4$ aggravated the scale adherence.