純鉄および Fe-Cr 合金の低温における降伏応力の温度および歪速度依存性について

概要

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Temperature and strain rate dependences of yield stress in purified pure iron and Fe-Cr alloys, were studied mainly by compression tests in the ranges of -196∿300℃ of temperature and 10^<-5>∿10^<-2>sec^<-1> of strain rate. Relations between temperature (T), strain rate (ε^^.) and frictional stress (σ_t), were established in the following manner : ε^^.=Cσ^n_t exp(-E/RT) This is applicable when σ_t is in the range of 5∿28kg/mm^2. Activation energy E is hardly dependent on temperature, stress and chromium concentration, being about 15kcal/mol. Strain rate exponent n, however, increases with increasing chromium content. It may be said that solid solutioning of chromium affects mainly n and C in the above equation, and further, that stress is chiefly attributable to entropy term rather than to enthalpy. Softening effect by solid solutioning is presumed to be mainly due to the increase of the strain rate exponent with increasing chromium concentration, in other words, to the increase of activation volume.
社団法人日本鉄鋼協会の論文
1971-05-01