Stress‐Corrosion Cracking of Alpha‐Brass Without Copper Oxidation

Transgranular stress‐corrosion cracking without copper oxidation has been demonstrated in α‐brass, confirming the findings of Bertocci, Thomas, and Pugh (1984), Cracks continued to propagate in monocrystals at potentials as low as −40 mV vs. a copper reference electrode in solutions. Residual Cu(II) in these solutions was no more than 1 μ M and polarized the reference electrode by no more than 3 mV from the equilibrium potential. Polycrystals showed similar behavior except that cracking was intergranular at −40 mV and transgranular at 0 mV or at the open‐circuit potential (−10 to −20 mV). Arsenical brass showed more rapid dezincification and possibly more rapid cracking than arsenic‐free brass. Impedance characteristics of copper and brass electrodes were measured, and the latter displayed pseudoinductive features due to the dezincification reaction.