不同加载应变率下钨合金变形及破坏机理研究

The Deformation and Fracture Mechanism of Tungsten Alloy Under Different Strain Rates

  • 摘要: 采用准静态压缩、霍普金森动态压缩以及爆炸加载3种不同加载方式,研究了钨质量分数为97.5%的高钨合金在不同加载应变率条件下的变形以及破坏机理. 试验结果表明:钨合金在应变率为10-4s-1准静态加载条件下,大量钨颗粒在与轴向呈45°方向发生拉伸塑性变形并在径向发生解理断裂;在应变率为103s-1量级的动态压缩条件下,钨合金在与加载应力呈45°方向发生了局部剪切,径向外表面发生钨-钨断裂以及钨颗粒解理断裂;爆炸加载应变率达到105~106s-1的条件下,钨合金内部产生大量钨颗粒碎块,且在个别钨颗粒内产生条状花样,同时钨颗粒内部产生大量形变孪晶作为裂纹萌生源,增加了钨合金内钨颗粒解理断裂. 钨合金在高应变率加载条件下为纯脆性断裂.

     

    Abstract: Three loading modes of quasi-static, Hopkinson dynamic compressing and explosive loading were used to study the deformation and fracture mechanism of tungsten alloy with 97.5% tungsten content in this research work. The results show that, under the quasi-static compressing, a large number of tungsten particles are elongated at the 45°directions with the axial direction and the cleavage fracture occurs in the radial direction. While under dynamic compressing with 103s-1 strain rate, the localized shear occurs at the 45° direction with the axial direction, the tungsten-tungsten fracture and the tungsten particle cleavage fracture also occur at the radial outer surface of the sample. When the strain rate is up to 105~106s-1, the tungsten particles irregularly break to fragments and the strip pattern appears in tungsten particles. At the same time, lots of deformation twins appear as embryonic zone of crack, which increases the cleavage fracture. The pure brittle fracture of tungsten alloy happens under high strain rate loading.

     

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