ON THE AMOUNT OF HYDROGEN ABSORBED IN STEEL BY PICKLING.

Abstract

During the pickling operation of steel, part of iron is dissolved into acid and evolves hydrogen. Some part of hydrogen, thus evolved, is absorbed in steel and causes many troubles during their after treatments. The author determined the effects of pickling time, temperature of acid and itS concentration on the amount of hydrogen absorbed in steel.
Specimens used were 0·3%, 0·7% and 0·9% carbon steels, of which the diameter and length were 15mm. and 50nm. respectively.
These were soaked in acid, washed, dried and then the amount of hydrogen quickly determined by the vacuum extraction method.
Following are the results obtained:-
(1) The amount of hydrogen absorbed in steel increases as the time of pickling increases, but the rate of increase gradually drops.
(2) The higher the temperature of acid, the more hydrogen is absorbed.
(3) The higher the acld concentration, the more hydrogen is absorbed at a temperature of 53°C, but scarcely any difference between concentrations of 10% and 20% is not observed at 70°C.
(4) The ratio of hydrogen absorbed to the hydrogen evolved is considerably great at the beginning of pickling, but after a few minutes this ratio decreases markedly.