The effect of W-W grain contiguity on the high shear strain rate deformation and failure behavior of 93W-5Ni-2Fe is studied using the torsional Hopkinson bar apparatus. High strain rate tests (at 1000/s) are conducted on torsion specimens made from 93%W material with two different W-W grain contiguities, 0.23 and 0.12. Different contiguities were obtained by subjecting the tungsten heavy alloy (WHA) to a cyclic heat-treatment of repeated isothermal holding at 1150°C and water quenching. As the contiguity is decreased, strain to failure increases at high rate loading. Failure stress was found to decrease with the decreasing contiguity. There were no significant changes in the yield stress of the two materials at high shear strain rate loading. Fracture surfaces of the specimens from high contiguity material show cleavage of W grains, brittle failure at the W-W grain interfaces and smooth shear localized failure. In contrast, there are dimple type ductile matrix fracture zones in the low contiguity material in addition to the cleaved W grain brittle W-W interface separation and smooth hear localized failure zones.
展开▼
