高应变率下热挤压态细晶钨合金的动态力学性能及失效行为

Dynamic Mechanical Properties and Failure Behavior of the Rapid Hot Extruded Fine-Grained Tungsten Heavy Alloy at High Strain Rates

摘要:

采用快速热挤压技术对细晶93W-4.9Ni-2.1Fe-0.03Y%进行变形强化，研究了高应变率下挤压态细晶钨合金动态力学性能及失效行为。结果表明：在较低应变速率下的挤压态细晶钨合金的屈服强度相近，约2000 MPa；断面上的钨颗粒被严重拉长直至破碎，破碎的细小钨颗粒粘附在软化的粘结相中，随着应变率的增加钨颗粒变形更加明显；剖面观察发现：沿着断裂面的钨颗粒发生了高度的剪切变形，而内部区域则基本没有变形，表现出了剪切局域化迹象。实验结果证明了挤压态细晶钨合金在动态加载条件下的失效方式是绝热剪切失效。

Abstract:

Fine grain 93W-4.9Ni-2.1Fe-0.03Y% alloy was strengthened by rapid hot extrusion. The dynamic mechanical properties and failure behavior were investigated for the rapid hot extruded fine grain tungsten heavy alloy at high strain rates. The results show that the flow stresses of the as-extruded fine-grained tungsten alloy at relatively lower strain rates are equivalent, of the order of 2000 MPa. Tungsten particles on the fracture surfaces are severely deformed and fracture into fine pieces which adhere to the soften matrix phase. This phenomenon is enhanced with the strain rate increasing. Observation of the sectioned surfaces reveals that the tungsten particles are heavily shear deformed along the fracture surface, but no plastic deformation is observed when it gets into the interior, indicating the localized shearing marks. The experimental results have proved that the failure of the extruded fine-grained tungsten heavy alloy is adiabatic shearing failure.