孪生诱发塑性对V-5Cr-5Ti合金应变硬化行为的影响

STUDY OF TWIP EFFECT ON STRAIN HARDENING BEHAVIOR IN V-5Cr-5Ti ALLOY

钒合金(V-Cr-Ti)作为潜在重要的聚变反应堆用结构材料,近年来受到广泛的关注.为了研究V-5Cr-5Ti合金不同应变率压缩下的应变硬化行为,特别是孪生对塑性变形的影响,以位错密度和孪晶演化为基础,建立了该合金的应变硬化模型.模型中考虑了孪晶中的位错滑移对材料塑性应变的贡献.模拟结果表明,由于孪生诱发塑性,从而使动态压缩时的位错密度小于准静态加载时的,这使得V-5Cr-5Ti合金在动态压缩时的应变硬化率比准静态加载时的小.当孪晶形成后,位错滑移引起的塑性应变率随应变增大而增大,并逐渐接近加载应变率,而孪生引起的塑性应变率则随应变增大而减小.

As an important potential structural material for fusion first-wall/blanket application, vanadium alloy （V-Cr-Ti） has been studied a great lot in recent years. In order to study the strain hardening behavior of V-5Cr-5Ti alloy under compressions with different strain rates, especially the twinning effect on the plastic deformation, the strain hardening model of this alloy has been constructed based on the evolutions of dislocation density and twin in this paper. The model considered that the slipping of dislocation in twins could contribute to the plastic strain. The simulation results indicated that strain hardening ratio of dynamic compression, which is smaller than that of quasi-static compression, is caused by dislocation density of the former smaller than that of the latter owing to twinning induced plasticity （TWIP）. After the twins formed, the plastic strain rate induced by dislocation slipping increases with strain increasing and approaches the loading strain rate, while the plastic strain rate induced by twinning decreases with strain increasing.