Abstract
The hardness-time curves at various annealing tempratures were explorated for cold-worked α-Brass containing 35.2%Zn,and its changes of electrical resistance were measured in the course of heating with a constant rate. The abnormal hardening processes could be treated as aging phenomena of strain-hardened type because of two facts obtained. First,between the logarithmus of time attained maximum hardness and the reciprocal of the absolute annealing temperature there existed some linear relations, from which the activation energies could be calculated for each working-degree and temperature range. The calculated values were almost conceivable. Second,in the alloy particularly annealed at about 225°C for one hour there evolved some abnormal strains which were confirmed from the resistance changes. In the lower range of working-degree, the “initial softening” followed by proper hardening process was observed also with a regular relation between time and temperature. The very slight hardening perceived sometimes in general just before the recrystalization may be evidently distinguished from the abnormal hardening in case of α-Brass.The above results were compared with those of α-Brass containing 26.5%Zn and a good agreement was gained.
