| Title |
Correlation of Microstructure and Dynamic Deformation Behavior in Tungsten Heavy Alloys |
| Authors |
김동국(Dong Kuk Kim); 이성학(Sung Hak Lee); 송흥섭(Heung Sub Song) |
| Keywords |
Tungsten heavy alloy; Dynamic deformation behavior; Tungsten particle size and shape; In situ fracture test; Cleavage fracture |
| Abstract |
Correlation of microstructure and fracture mode with the dynamic torsional behavior was investigated on tungsten heavy alloys whose size and shape were changed using the sintering conditions such as sintering temperature, time, and cycle. Dynamic torsional tests were conducted for seven specimens, four of which were fabricated by the repeated sintering process, using torsional Kolsk bar, and then the test data were compared via microstructures, mechanical properties, adiabatic shear banding, and fracture mode. With increasing the sintering temperature and time, the size of tungsten particles was increased, and their hardness became higher, thereby deteriorating fracture toughness. The dynamic torsional test results indicated that in the specimens whose tungsten particles were coarse and irregular-shaped, cleavage fracture occurred in the center of the gage section with little shear deformation, whereas shear deformation was concentrated into the center of the gage section in the conventionally processed specimens. The deformation and fracture behavior of the specimens having coarse tungsten particles correlated well with the observation of the impacted penetrator specimens and the in situ fracture test results. i.e., microcrack initiation at coarse tungsten particles and cleavage crack propagation through tungsten particles. These findings suggested that there would be optimum tungsten particle size since the cleavage fracture mode would be beneficial for the self-sharpening. |