SLOW STRAIN RATE AND CONSTANT LOAD TESTS OF A-285 AND A-516 STEELS IN BAYER SOLUTIONS

Stress corrosion cracking (SCC) experiments were carried out on A 285 and A 516 steels by slow strain rate and constant load techniques. The influence of the impurities contained in Bayer solution on the susceptibility to SCC was studied. The results obtained by both techniques indicated that aluminate ions promote passivation but the oxide layer includes numerous defects and the SCC susceptibility increases. The slow strain rate experiments provided a rapid method for investigating caustic stress corrosion cracking and intensified the susceptibility to SCC compared to the results obtained by the constant load technique. In the passive potential region, some shallow cracks were detected only when the experiments were conducted at slow strain rate in solutions containing aluminate ions. The presence of such cracks indicated that anodic protection could not entirely prevent SCC in the Bayer solution.