The probability of vanadium hydrogenation in the course of metallographic preparation

Embrittlement of vanadium foil during foil electropolishing has been noted in cases when the oxide layer formed during polishing is removed as a result of changed specimen polarity (the specimen time under negative potential was 30-40 s.). Lamella formations with a certain distinct orientation are observed in some grains of the recrystallized, cathode-polarization-polished vanadium foil. Metallographic inspection reveals that the amount of grains with lamella formations increases with time. When cathode polarization time is increased to 2 min the proportion of grains with plate-shaped formations is approximately 70% of total grain number. No changes in specimen polarity, at least for specimens in the form of thin foils, is tolerable during vanadium electrochemical polishing. In order to remove the oxide layer, the specimen should be vigorously rinsed in water and, if necessary, wiped with wetted cotton wool