TA2钛金属柱壳外爆绝热剪切碎裂及微观组织演化

Multiple Adiabatic Shear Fragmentation and Microstructure Evolution of Explosive-Driven TA2 Pure Titanium Cylinders

对绝热剪切敏感TA2工业纯钛柱壳在不同爆压下开展碎裂试验,通过对软回收碎片的宏观、微观分析,探讨金属柱壳爆炸膨胀断裂模式及机制。结果表明,不同爆压下,TA2工业纯钛柱壳外爆碎裂虽然均为剪切断裂模式,但其断裂机理不同;在较低爆压作用下,发生微孔洞演化、连接的剪切断裂;而在较高爆压下,为多重绝热剪切控制的断裂机制。在爆炸作用下,TA2钛柱壳高速变形、断裂过程发生α→β动态相变,随后在稀疏波作用下快速冷却,试样内表面组织转变为一定取向的板条马氏体,晶粒明显大于原始尺寸。因此,对于柱壳外爆碎裂特性及机理分析,须考虑材料在爆轰波作用下金属材料的动态相变的影响,该研究为柱壳断裂存在多种断裂模式及碎裂分析提供了参考。

The fragmentation experiments of TA2 industrial pure titanium cylindrical under different explosion pressures were carried out.Through the analysis of macroscopic microscopic and fracture for the recovered fragments,the fracture mode and mechanism of explosively fragmentation of TA2 metal were discussed.The results show that though the fracture modes of TA2 cylinder are all shear fracture in explosive-driven cylinders expansion tests,the failure mechanism of shear mode is different for tests under different explosion pressures.It is observed that the shear failure is caused by the evolution of micro-voids in tests under relatively low pressure but controlled by multiple adiabatic shear under the higher explosion pressure.The microscopic metallography shows that the dynamic phase transition ofα→βmay occur during the high-speed deformation of the TA2.It is shown that the microstructure of the inner surface is converted to lath martensitic with a specific orientation and the grain size is apparently larger than the as-received grain size.Thus,it is necessary to consider the influence of the dynamic phase transition of material under the action of the shock waves when analyzing the fracture characteristics and mechanism of external explosive experiments.This work can provide a significant reference to the analysis of multiple failure modes of cylinders under external explosion loading conditions.