The principles, advantages, and implementations of scanning reference electrode techniques are reviewed. The technique locates the position of localized corrosion, and can be used to monitor the development of corrosion and changes in the corrosion rate under a wide range of conditions. Data related to pitting, intergranular corrosion, welds, and stress-corrosion cracking are presented.

The stresses produced in a solid by cavitation generated in distilled water by 10-, 20-, and 30-kHz vibrations have been determined by a transducer technique. The measured stress pulses are attributed to the concerted collapse of the whole cloud of bubbles created by the pressure changes in the water rather than to the independent effects of individual bubbles. The magnitude and duration of the stress pulses are characteristic of those of a shock wave and can be related directly to the degree and mode of damage which they produce in a solid.

The stress corrosion cracking (SCC) of sensitized Type 304 stainless steel in thiosulfate solutions has been studied using constant extension rate tests. Very low concentrations of about 6.10−7M Na2S2O3 (0.1 ppm) gave cracking. With boric acid added, higher concentrations (1 ppm) were required. The SCC was shown to be electrochemically controlled. Below −0.5 VSCE (−0.75SHE) no SCC took place; above this potential, the rate of SCC increased with potential. Straining was required before SCC continued at 0.5 V if the potential was held at or below −0.5 V for extended times.

No abstract