本文研究了12Ni3CrMoVA合金钢流变应力随温度及应变速率的变化规律,以及组织因素的影响,测算了该材料激活能及激活体积等热激活参数。根据P-N机制由螺型位错芯结构分析了bcc金属的塑性形变规津,该规律同试验结果吻合,说明有效应力与温度关系曲线中的拐点是由于Peierls势能呈双驼峰分布所致,相应的位错线激活态形状呈双扭折对分布。显微组织仅影响位错的长程障碍阻力,而对位错热激活运动没有影响。
The 12Ni3CrMoVA steel was selected to investigate the effect of tem-perature, strain rate and microstructure on yield strength of bcc metals. The therma-lly activated parameters, such as activation energy and volume, were measured andcalculated. According to the P-N mechanism, the plastic deformation of bcc metalswas analysed by the core structure of screw dislocation, the theoretical predictionwas in good agreement with experimental results. It is explained that the "turningpoint" in curve of effective stress against temperature was caused by a double cam-el-hnmp--shape of Peierls potential energy, which resulted in a new pair of doublekinks forming in the front of original one. The microstructure can only affect on athermal stress, but not affect on thermally activated movement of dislocation.
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