金属材料屈服强度的应变率效应和热激活理论

CORRELATION BETWEEN YIELD STRESS AND STRAIN RATE FOR METALLIC MATERIALS AND THERMAL ACTIVATION APPROACH

对４种金属材料进行了应变率为１０^（－４）—１０~３ｓ^（－１）的拉伸试验，结果表明，屈服强度随应变率的升高分两阶段线性升高．提出了位错线热振动对加载频率响应的热激活作用机理，依据该机理计算所得Ⅰ、Ⅱ区临界应变、与实测值相符、并在此基础上将应变率对屈服强度影响的机制图重新划分为：Ⅰ区、富热激活区；Ⅱ区，贫热激活区．

The effect of the strain rate on tensile behaviour has been investigated for 4 metallic materials. From the tests, a two-stage linear relation has been found between yield stress(σ_s) and strain rate(ε),σ_s=σ_0+klgε. A new mechanism of thermal activation produced by the response of thermal vibration of dislocation lines to loading frequences was suggested, from which the critical strain rate calculated is in agreement with the measured one.Base on these studies the disspative map of the effect of ε on σs can be re-divided into rich-, poor-thermal activation region.