Comparative Findings Using the Slow Strain-Rate, Constant Flow Stress, and U-Bend Stress Corrosion Cracking Techniques

Abstract

The testing of materials for stress corrosion cracking (SCC) in a use environment involves the risk that cracking may not be found by the test technique. When this happens, immunity to SCC may be incorrectly concluded. To avoid this type of error, the use of multiple testing techniques is recommended. This report discusses the different findings for Type 304 stainless steel obtained by three SCC testing techniques: the slow strain-rate technique (SSRT), the constant flow stress (CFS) test, and the U-bend test. The comparative studies in 36.5 percent magnesium chloride solution show that the cracking mode has an electrochemical potential dependency. In sodium chloride solutions, in the range of 1 to 20 percent concentration, the studies show that the cracking has a critical strain-rate dependency.