Comparative Methods for Measuring Degree of Sensitization in Stainless Steel

Abstract

Three test methods for determining degree of sensitization in austenitic stainless steels have been investigated. The results clearly show that all three test methods are capable of detecting moderate-to-severe degrees of sensitization, but the electrochemical potentiokinetic reactivation technique is the most sensitive for quantitatively determining the levels of sensitization which are of primary concern for industrial use. Both the ASTM Recommended Practices for Detecting Susceptibility to Intergranular Attack in Stainless Steels (A 262-75, Practice A) and the electrochemical potentiokinetic reactivation methods appear to saturate at high degrees of sensitization, which results in a loss of discriminating power between different heats of material. While the A 262, Practice E, method does not appear to saturate and retains its discriminating power at high degrees of sensitization, it is not a suitable method for detection at the lower degrees. Of the three test methods, it appears that the electrochemical potentiokinetic reactivation test is the most suitable for determining the quantitative degree of sensitization over the levels of industrial concern.