Isao Gokyu1 and Junji Kihara1
1Department of Metallurgy, Faculty of Engineering, The University of Tokyo, Tokyo
It is observed how the deformation resistance and work hardening behavior of tough-pitch copper and 0.02% carbon steel, are influenced by the deformation speed. The order of magnitude of the deformation speed is 10-3/sec (by the Olsen material tester), 102/sec (the counter-blow forging tester) and 104/sec (with the high speed deformer made of ``Drive'it rivetting machine'') as the strain rate. In the case of copper strain-rate dependence of deformation resistance is smaller than in that of iron. However, the work hardning behavior of copper depends upon the strain rate, but that of iron does not depend on the strain rate at all except when deformation goes with twin deformation. Therefore, the strain-rate dependence of deformation resistance of copper is due to that of work hardning behavior, but in the case of iron the strain-rate dependence of deformation resistance is due to that of frictional resistance in the crystal itself.
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