α黄銅単結晶のSCC(<小特集>腐食防食小特集)

概要

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Although there are many reports on stress corrosion cracking of α brass polycrystals in ammoniacal environment, few reports deal with α brass single crystals. So, in order to examine the effect of slip step on the initiation of stress corrosion cracking and the propagation mechanism of cracks, stress corrosion cracking tests were performed on Cu-27.8at% Zn alloy single crystals (α brass) oriented to <321> and <211> in ammoniacal vapor at 298±1 K. On α brass single crystals, stress corrosion cracking did not initiate at lower stress than the yield stress which is necessary to move dislocations. The preformed slip steps did not influence the initiation of stress corrosion cracking, but the microcracks initiated from the slip steps caused by the active slip plane at higher stress than the yield stress. The orientation of the initiated cracks corresponded to {111} trace. Then the cracks propagated along {110} trace. On the specimen oriented to <211> where the conjugate slip system becomes active from the beginning of the tests, the cracks initiated at the area where dislocations were piled up by Lomer-Cottrell barrier.
1983-11-15