Abstract
The influence of cyclic strain on the corrosion rate of cast steel was studied for 90 days in tap water with potassium chromate, (I), and with sodium nitrite, (II). Unstrained specimens were nearly protected from corrosion in solutions (I) and (II). However, heavy corrosion was found at the stress concentrated area of (I) in tests where a cyclic strain was imposed. Negative current loops in anodic polarization curves were observed in (I) for specimens finished with emery cloth. No negative current loops were observed for the rusted specimens. No negative current loops in anodic polarization curves were observed either in finished or rusted surfaces in (II). The following two conclusions can be derived from the test results. The cast steel was initially in an unstable passive state in the potassium chromate solution. The presence of the low cyclic strain disrupted the formation of a passive film, and corrosion heavily progressed. Anodic polarization curves in the presence of anodic inhibitors are useful to predict whether corrosion will progress or not under a cyclic strain condition.
