Evaluation of the EPR Technique for Measuring Sensitization in Type 304 Stainless Steel

The electrochemical potentiodynamic reactivation (EPR) technique has been used to measure the degree of sensitization in type 304 (UNS(1) S30400) stainless steel with 0.052% C. In the first part of the work, the dependence of EPR results on testing temperature is quantified, thus permitting the conversion of field testing results to laboratory conditions. Automatic image analysis has additionally been used to characterize the intergranular corrosive attack produced by EPR testing. Results correlate well to the electrochemical measurements and also form the basis for an improved equation for the evaluation of the degree of sensitization. In the second part, the correction for testing temperature differences is applied to the results of a European round robin on EPR testing.