Masanobu Ohmori1, Yoshitoyo Yoshinaga1 and Hideyo Maniwa2
1Faculty of Engineering, Hiroshima University, Hiroshima
Two kinds of copper specimens, a pure copper for industrial use and an OFHC copper, were deformed under various stress states and strain rates at temperatures between room temperature and 600°C. Both of the coppers showed an intermediate temperature embrittlement (less ductility) when deformed slowly, but showed no embrittlement when deformed rapidly. Grain boundary slidings or cracks along boundaries were produced on the surfaces of the specimens deformed in a brittle manner. On the contrary, no boundary sliding and crack were found in the specimens deformed rapidly over a temperature range in which the slowly deformed specimens revealed slidings or cracks.
From the present study, it has been concluded that the intermediate temperature embrittlement of copper may be attributed to a viscous behaviour of grain boundaries.
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