高速冲击下钢板的微观组织及绝热剪切带

用烧结的钨合金弹丸垂直冲击45钢与30CrMnMc钢两种钢板,45钢钢板穿孔周围的微观组织沿径向可分为熔化快凝层、再结晶细晶层、变形细晶层,形变层及正常基体组织,该材料中没有发现绝热剪切带．30CrMnMo钢板穿孔周围的微观组织表面是熔化快凝层,其下是扩散层、形变层和基体组织,钢中形成了几类绝热剪切带,由于冲击波和反射波的作用、复杂的塑性变形及侵彻过程本身的原因,它们具有不同的方向和宽度冲击45钢钢板和30CrMnMo钢钢板的弹丸的变形形式相差很大,冲击45钢钢板的弹丸被墩粗且损耗较慢,冲击30CrMnMo钢钢板的弹丸为剪切变形,损耗速度快．分析表明,绝热剪切带的发生与材料的强度、冲击下材料的应变量有关．

MICROSTRUCTURES AND ADIABATIC SHEAR BANDS FORMED IN STEEL PLATE UNDER HIGH RATE IMPACT

The projectiles of sintered tungsten alloy were fired directly on steels 45 and 30Cr-MnMo target plates. The microstructures near the perforation of steel 45 target plate can be divided along radial direction as: melted and rapidly solidified layer, recrystallized fine-grained layer, deformed fine-grained layer, deformed layer and normal matrix. The adiabatic shear bands (ASBs) cannot be found in this intermediate strength steel. Observation of the microstructures around the radial direction of perforation of 30CrMnMo steel target plate shows that there is a melted and rapidly solidified layer on the surface of perforation, underneath there is a diffusing layer, and then a fine-grained layer appears as streamlines. Several kinds of ASBs are found in this high strength steel, they have different directions and widths, which are relative to the shock waves and reflect waves and the complex deformation during penetration process. The deformations of projectiles are rather different when they impacted to different target plates. The projectile impacted on steel 45 target plate is tamped and exhausted slowly, while the projectile impacted on 30CrMnMo steel target plate is sheared and exhausted quickly. It indicates that the appearance of ASBs is relative to the strength and the strain of the materials under impact.