EFFECT OF TUNGSTEN PARTICLE-SHAPE ON DYNAMIC DEFORMATION AND FRACTURE-BEHAVIOR OF TUNGSTEN HEAVY ALLOYS

The effect of the tungsten particle shape on the dynamic deformation a nd fracture behavior of tungsten heavy alloys was investigated. Dynami c torsional tests were conducted using a torsional Kolsky bar for five alloys, one of which was fabricated by the double-cycled sintering pr ocess, and then the test data were compared via microstructures, mecha nical properties, adiabatic shear banding, and fracture mode. The dyna mic torsional test results indicated that in the double-sintered tungs ten alloy whose tungsten particles were very coarse and irregularly sh aped, cleavage fracture occurred in the central area of the gage secti on with little shear deformation, whereas shear deformation was concen trated in the central area of the gage section in the other alloys. Th e deformation and fracture behavior of the double-sintered alloy corre lated well with the observation of the impacted penetrator specimen an d the in situ fracture test results, i.e., microcrack initiation at co arse tungsten particles and cleavage crack propagation through tungste n particles. These findings suggested that the cleavage fracture mode would be beneficial for the self-sharpening effect, and, thus, the imp rovement of the penetration performance of the double-sintered tungste n heavy alloy would be expected.