Can polyoxysulfuric acid cause intergranular corrosion in stainless steel?
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I saw the drawings for hydrogenation equipment from a chemical engineering design institute in Guizhou Province, which specified that intergranular corrosion tests be conducted on the stainless steel material used in the composite panels. I know that during shutdowns for maintenance, polyoxysulfuric acid can form on the inner surface of the equipment, and this substance can cause stress corrosion in stainless steel. I would like to ask everyone: can polyoxysulfuric acid also cause intergranular corrosion? If intergranular corrosion cannot occur, then why conduct intergranular corrosion tests?
It seems there could be intergranular corrosion; I read relevant experimental reports while studying.
The corrosion of austenitic stainless steel by polydisulfates is actually corrosion cracking of sensitized stainless steel; un sensitized stainless steel does not experience corrosion cracking. Therefore, it is reasonable to require intergranular corrosion testing.
Polyoxysulfuric acid poses a risk of intergranular stress corrosion cracking in austenitic stainless steels. Corrosion testing is not related to this; intergranular corrosion testing is primarily used to determine whether the raw material has been affected by sensitization, such as whether it has undergone proper solution treatment in its supply state, or whether welding has caused sensitization of the material. Corrosion testing is used to select qualified materials, not to evaluate their corrosion resistance.