Stress corrosion cracking test with slow strain rate and constant current

A rapid electrochemical tension test was developed for evaluating stress corrosion crack initiation in carbon steel. Constant anodic current was imposed on smooth-bar tension specimens as the specimens were slowly strained to fracture at 1.3 x 10-6/s. Equivalent results were obtained for the following ductility properties measured: uniform elongation, total elongation, and reduction of area. Total elongation was chosen as the index for stress corrosion crack initiation. An equation was developed that allowed calculation of total elongation of specimens in electrolytes (test solutions) with composition ranges of 1.5 to 5.5 M nitrate, 0 to 3.5 M nitrite, and 0 to 5.0 M hydroxide, and a temperature range of 50 to 1000C. A minimum of 13% total elongation was selected to indicate the possible initiation of cracking in A 285-B steel alloy. The test was used to evaluate relative aggressiveness of synthetic nuclear wastes on A 285-B carbon steel and the relative resistances of several steels to given solution compositions. Test results formed one of the bases for setting temperature and concentration limits for several ions in nuclear wastes that are stored in carbon steel tanks at the Savannah River Plant