Untersuchung der lokalen Korrosionserscheinungen an den Schweißnähten in Apparaturen aus nichtrostendem Stahl

Investigation into local corrosion phenomena at the welds in chemical apparatus of stainless steel Corrosion phenomena at the welds of apparatus consisting of stainless steel can only be investigated in an active medium. The active medium used for this purpose was a 5 pC hydrochloric acid where virtually all the incidental electro–chemical phenomena disappear, and where the corrosion rate is exclusively determined by the transit potential at the boundary between plate and weld. The paper describes the preparation of the specimens, the design of the measuring cell, and the testing procedure adopted. In this way, a “hydrochloric acid test” was developed which permits a rapid distinction between “good” and “poor” welds of specimens. The reliability of the hydrochloric acid test is corroborated by recording the current density/potential characteristics in 5 pC hydrochloric acid. The technique of recording these characteristics with the aid of the potentio-kinetic method is described, and illustrated by photographs and diagrams.