Quantitative inspection of iron contamination on 304 Austenitic stainless steel

The iron contaminated sample of 304 Austenitic stainless steel and a clean sample after chemical passivation was chosen to introduce a new method for quantitative inspection on iron contamination, and the relationship between evaluation results and the character parameter of electrochemical corrosion was analyzed. The result showed that the measured a* value from the inspection increased with increasing iron contaminant, while the a* is close to zero for the chemical passived sample. Although the measured a* was decreased after the contaminated samples was exposed in air and 3.5 wt.% NaCl solution, the inspection method can still quatitatively evaluate on the iron contaminant. The a* value has a linear relationship with the corrosion potential and breakdown potential from electrochemical polarization test. It was conformed that the chromogenic quantitative inspection method could adequately evaluate on the iron contamination.