粉末焼結体の変形抵抗に対するひずみ速度の影響

概要

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Upsetting tests of sintered aluminium and iron powder preforms are carried out using a computer-controlled high-speed press which can generate a constant strain rate throughout an upsetting process. The effect of strain rate on the flow stress and the density change of these sintered metals are experimentally examined under various constant strain rates from 0.001 to 50/s. The effect of strain rate on the material constants N, a and b which are included in the plasticity theory of porous materials presented by Oyane and Shima is also discussed. Experimental results show that the strain rate hardly affects either the density change or the material constants in the Oyane and Shima plasticity theory, but that the flow stress of sintered metal increases with increasing strain rate. Such strain-rate dependence of the flow stress of sintered metals is estimated to result from that of the matrix itself, i.e., the strain rate sensitivity of pore-free aluminium and iron.
1994-02-25