93W杆式弹超高速撞击多层Q345钢靶毁伤及微观分析

为了解杆式弹超高速撞击多层薄钢靶的破坏过程及毁伤机理，开展了克级93W杆式弹正撞击多层Q345钢靶实验及数值模拟研究，通过扫描电子显微镜（scanning electron microscope，SEM）及金相显微镜，分析了超高速撞击实验后靶板材料的微观组织及成分。结果表明，超高速撞击作用下，靶板呈现出“翻唇”穿孔变形、花瓣状塑性变形、撕裂、撞击成坑及鼓包等破坏模式。靶板前3层毁伤以超高速穿孔为主，孔洞数目多但面积小，后几层靶板毁伤孔洞数目少且孔径呈先增大后减小趋势。微观分析表明靶材在强冲击压力下发生晶粒碎化、熔化及再结晶，撞击过程中会形成微孔聚集与微裂纹，可见靶板失效主要是熔融混合物冷却过程中产生的热应力与切应力下的剪切撕裂综合作用的结果。

Damage of a multi-layer Q345 target under hypervelocity impact of a rod-shaped 93W projectile

In order to research the penetration characteristics and damage mechanism of multi-layer targets under hypervelocity impact, experiments and numerical simulations were carried out on a rod-shaped 93W projectile impacting a multi-layer Q345 steel target. A gram-order rod-shaped 93W projectile together with a sabot was launched by a 57/10 mm two-stage light gas gun to penetrate into a ten-layer Q345 target. The damage photos of the target after penetration were transformed into binary images by a Matlab processing software. The equivalent diameter of the center hole, the number and total areas of the holes, the diameters of damage circles of the ten-layer target were summed up and analyzed. The AUTODYN software was used to perform the smoothed particle hydrodynamics simulation. Then the microscopical data of the target plates were obtained by scanning electron microscopy (SEM) and optical microscopy to analyze the microstructure and element composition. Results show that a rod-shaped 93W projectile could penetrate 8 or 9 layers of a ten-layer Q345 target under different initial impact velocities. Perforated lips, petal-shaped plastic deformation, tearing, cratering and bulging were formed in target plates. These failure modes are attributed to plastic expanding failure and shear tearing under shear stress. The damage mode of the first three layers of the target is dominated by hypervelocity perforation due to the high impact velocity, with many holes but small area, while the holes in the later layers are few, but the diameter increases first and then decreases as the masses and velocities of fragments decrease. The simulation results were verified by the experimental results. They are in good agreement with the experimental results. Micro analysis shows that the materials of the target and projectile are melt, while the grains are broken up, refined, melt and recrystallized in the target plates. There are aggregated micropores and microcracks formed during the penetration process. The micro analysis results show that the damage failure is mainly caused by the combined effects of thermal stress during the cooling process of the molten mixture and shear tearing under the shear stress, which is consistent with the macro-scopical results.