应变水平对锆合金动载下塑性变形机制的影响

基于实验设计研究了应变参数对锆合金动载下塑性变形机制的影响。通过控制应变速率,采用应变限位环的方法实现了锆合金高应变速率下应变参数的单一分离,应变速率为2300 s~(-1)时,获得了4个不同的应变水平:0.11、0.21、0.30、0.33。基于锆合金高应变速率不同应变下微观组织的表征,预测了应变参数对锆合金动载下塑性变形过程的影响。结果表明:形变带和转变带是锆合金不同应变阶段塑性变形的重要方式,形变带内部由严重变形的晶粒组成,而转变带内部主要由100~300 nm的细小等轴晶粒组成。在变形初始阶段,锆合金变形以柱面滑移和锥面滑移为主,以孪生为辅;随着应变的增加,位错持续增殖,位错的塞积导致应力增加,直至最大抗压强度;当应变达到一个临界值时,形成形变带;随应变继续增加,形变带发生动态再结晶,演化为转变带;应变继续增加,便会在剪切带内部诱发微空洞、微裂纹,直至材料断裂。

Influences of Strain on the Plastic Deformation Mechanism of Zirconium Alloy subjected to dynamic loading

The influence of strain on the plastic deformation mechanism of zirconium alloy subjected to dynamic loadings was investigated by means of the experimental design in this paper. The strain parameter of zirconium alloy subjected to dynamic loading was only separated by the strain stopping rings and the the controled strain rate, and four strain levels including 0.11, 0.21, 0.30 and 0.33 were obtained at a strain rate of 2300 s_-1. The results show that the deformed bands and transformed bands were considered as the dominant plastic deformaton mechanism of zirconium alloy under different strain stages. The deformed bands were mainly composed of the severe deformed grains, and the transformed bands mainly composed of the ultrafine and equiaxed grains with the mean diameter of about 100~300 nm were confirmed. Based on microstructural characterization of zirconium alloy under high strain rate and different strains, the plastic deformation process of zirconium alloy subjected to different strain parameters was speculated.