强织构纯钨金属中绝热剪切失稳行为的演化与调控

Evolution and regulation of adiabatic shear instability behavior in highly textured pure tungsten

具有高绝热剪切敏感性的高密度、高强度金属一直是动能穿甲弹的首选材料,绝热剪切失效导致的弹体端部“自锐”效应能够有效提升其侵彻打击能力.本文通过轧制变形预先在纯钨板材中引入强织构组织,动态单轴压缩实验和微观结构表征显示:强烈的择优取向设计是实现难熔重金属中绝热剪切失稳的重要手段.结合介观晶体塑性模拟研究,我们系统分析了强织构纯钨中绝热剪切带(Adiabatic Shear Band,ASB)形成与演化的过程,包括:局部剪切变形的开启与扩展;剪切区内热塑性累积至变形失稳;热塑性流动形成ASB并生长的不同阶段;揭示了各向异性动态剪切失稳行为的微观机制.同时,我们通过调控变形工艺获得了以不同晶体取向为主的轧板织构,研究了织构演化及取向空间分布变化对动态失稳行为的重要影响,明确了织构设计调控力学行为的有效性.

High-density,high-strength metals with high adiabatic shear sensitivity are always the favored materials for kinetic energy armor-piercing projectiles.The"self-sharpening"effect caused by adiabatic shear failure at the end of the projectile can effectively enhance their penetration capability.In this research,a strong texture is introduced into a pure tungsten sheet by prerolling deformation.Dynamic uniaxial compression tests and microstructure characterization reveal that a strong preferred orientation design is an important way to achieve adiabatic shear instability in refractory heavy metals.The formation and evolution process of adiabatic shear bands(ASB)in strongly textured pure tungsten is systematically analyzed,including the onset and propagation of local shear deformation,thermoplastic accumulation in shear zone to deformation instability,and formation and growth of ASB due to the concentrated thermoplastic flow.This reveals the microscopic mechanisms of anisotropic dynamic shear instability behavior.Moreover,the rolled sheet texture with different crystal orientations was obtained by adjusting the deformation process.The important influence of texture evolution and spatial distribution of grain orientations on the dynamic instability behavior was investigated,and the effectiveness of texture design in regulating mechanical behavior was clarified.