Hydrogen evolution from duralumin exposed to acid salt solution

The evolution of gas from duralumin corroding in an aqueous solution containing 10 g. of HCl + 30 g. of NaCl per litre of solution was studied. To obtain reproducible gas‐evolutions it was found necessary to control specimen surface pre‐treatment and the temperature and composition of the corrosion solution. Duralumin which corroded by pitting evolved gas at an approximately constant rate after an induction period of several hours. The same duralumin, heat‐treated so that it was susceptible to intergranular attack, evolved gas at a rate increasing linearly with time of immersion, after a short induction period.