Ti-6Al-4V弹体破坏模式对冲击反应的影响研究

Ti-6Al-4V材料是武器结构轻量化时的重要替代材料，其冲击反应将可能增加战斗部毁伤威力，但目前缺乏对其冲击反应条件及反应机理的研究。本文将采用试验与理论分析方法，研究结构破坏模式对Ti-6Al-4V材料冲击反应的影响，获得其冲击反应条件及反应机理。设计并开展了钛合金弹（头部与壳体均为钛合金）与复合弹（头部碳/碳复合材料、壳体空心钛合金圆柱）正侵彻混凝土试验，撞击速度在222~1008 m/s之间。钛合金弹激发了剧烈的氧化冲击反应，但复合弹未产生冲击反应。破坏模式宏细观分析显示，钛合金弹侵彻后宏观结构基本完整，仅表面发生摩擦磨损，以细观组织剪切变形为主要失效模式，形成尺寸在微米量级至百微米量级的颗粒碎片，碎片个数可高达3×106。复合弹的钛合金空心圆柱被撕裂成块，撕裂面沿剪切带方向发展，碎块尺寸在毫米或以上量级，个数至多百余个。碎片供氧和供热的效率均与碎片尺寸成反比，而特定供氧与供热条件下，碎片尺寸足够小是Ti-6Al-4V材料发生冲击反应的必要条件，这是钛合金弹发生冲击反应而钛合金空心圆柱无法激发冲击反应的本质原因。在具备冲击反应必要条件的前提下，碎片个数越多，冲击反应烈度越高。

Study on the impact initiated reaction of Ti-6Al-4V prejectiles by the fracture modes

Ti-6Al-4V is a kind of important alternative material for light-weight design of warhead whose impact-initiated reaction could enhance the damage power of the weapon. However, there is not enough research on the condition and mechanism of its impact-initiated reaction. Through experimental and theoretical analyses, the influences of fracture modes of Ti-6Al-4V structure on impact initiated reaction were studied in the present paper, in order to obtain the condition and mechanism of impact-initiated reaction of Ti-6Al-4V material. Two types of projectiles were designed to normally penetrate the unreinforced concrete target, i.e., the titanium projectile with ogival nose and the composite projectile with C/C nose and hollow titanium cylinder. The impact velocity followed between 222 m/s and 1008 m/s. Two projectiles exhibit different fracture modes. In the studied velocity range, there is an impact-initiated reaction during penetration for the titanium projectile, but no reaction is observed during the impact of the composite projectile. The fracture modes of the two projectiles were analyzed in the macroscopic and microscopic views. After penetration, the structure of the titanium projectile is almost intact. Only abrasion is observed on the outer-surface of the projectile. The main failure mode for abrasion is the shear deformation of its microstructure, which induces fragments with lengths in micrometers or hundreds of micrometers. The number of fragments could be up to 3 millions. For the hollow titanium cylinder in the composite projectile, it is teared up into large fragments, whose dimensions are in millimeters. The tearing surface develops along the shear band. The largest number of fragments is almost 120. Further analyses indicate that the efficiency of oxygen and heat supply is reverse proportional to the size of the fragment. Under certain oxygen and heat supply, the necessary condition to initiate the impact reaction of Ti-6Al-4V is that the size of fragments should be small enough. This must be the essential reason for the impact reaction in an ogival titanium projectile and no reaction in a composite projectile during penetration. With the necessary condition to initiate the impact reaction, the greater the number of fragments, the higher the impact reaction intensity is.