壁厚对HR2钢柱壳爆轰加载下膨胀断裂行为的影响

通过对6、12 mm两种不同壁厚的HR2钢柱壳进行爆轰加载实验，对其断裂碎片的宏观形貌、断口的微观形貌以及横截面的变形微观结构进行系统表征，研究了金属柱壳在爆轰加载下的膨胀断裂机理。结果表明，在膨胀断裂过程中壳壁厚度的增大导致HR2钢柱壳由纯剪切断裂变为拉剪混合的断裂模式。断裂碎片的微观结构分析结果表明，柱壳的断裂实际上是剪切裂纹从样品内部剪切带形核并扩展、和拉伸裂纹沿柱壳外表面的形核扩展的共同作用及竞争的结果。薄壁柱壳断裂由样品内裂纹沿剪切带的形核和扩展主导发生剪切断裂，而厚壁柱壳中内侧的裂纹沿剪切带的形核和扩展，但是最外侧则为环向拉应力主导发生拉伸断裂，因此表现出拉剪结合的断裂模式。

Effect of Shell Thickness on Expanding Fracture Behavior of HR2 Steel Cylinders under Explosive Loading

To clarify the fracture mechanism of metal cylinder under explosive loading, HR2 steel cylinders with shell of 6 and 12 mm in thickness respectively were subjected to explosive loading. The fracture fragments were collected after explosion, and then systematically investigated in terms of macroscopic morphology, fracture morphology and deformation microstructure. It is found that when the shell thickness increases, the fracture mode of HR2 cylinder changed from shearing fracture to the mixture of shearing fracture and tensile fracture. The deformation microstructure observation indicates that the failure and fracture of cylinder shell are the result of the combination and competition of cracks-nucleating and -expanding from the shear band and from the outer surface. The fracture of thin cylinder is dominant by the cracks nucleating and expanding from the shear band, presenting shearing fracture mode. The fracture of thick cylinder is the combined action of cracks-nucleating and -expanding from the shear band and from the outer surface, presenting a mode of mixture of shear- and tensile-fracture.