The Influence of Surface Iron Contamination on the Localized Corrosion Resistance of Austenitic and Duplex Stainless Steel, Studied with a Novel Rust Deposition Method

The influence of iron contamination on a stainless steel surface was evaluated based on a novel rust deposition procedure. The main variables that control the corrosion process and the influence of iron contamination on localized corrosion resistance of austenitic and super duplex stainless steel were investigated. Cyclic potentiodynamic polarization tests and environmental exposure with different rust surface contamination degrees were performed. Potentiodynamic polarization curves showed that iron contamination deteriorated the local corrosion resistance of both stainless steels. Environmental salt-spray exposure results indicated that the alloy resistance to rust contamination increased with the materials’ pitting resistance equivalent. Likewise, the extent of localized corrosion decreased with the rust contamination degree. These findings suggested that preferential corrosion from rust contamination was associated with the occluded solution chemistry. Environmentally friendly cleaning methods, including chemical treatments and laser cleaning, were evaluated as alternatives to hazardous pickling based on hydrofluoric-nitric acid. Last, practical recommendations for rust contamination of stainless steel are addressed.