Dynamic and quasi-static torsional behavior of tungsten heavy alloy specimens fabricated through sintering, heat-treatment, swaging and aging

Abstract

Dynamic and quasi-static torsional deformation behavior of a 93W-4.9Ni-2.1Fe tungsten heavy alloy (WHA) was investigated in order to evaluate the possibility of forming adiabatic shear bands. Dynamic torsional tests were conducted using a torsional Kolsky bar for the four WHA specimens fabricated through each processing condition, e.g. sintering, heat-treatment, swaging, and aging, and then the test data were compared with those of the quasi-static tests. The dynamic torsional test results indicated that the shear stress increases, while the shear strain decreases, with the maximum shear stress increasing in the order of the as-sintered, the as-heat-treated, the as-swaged, and the as-aged specimens. The as-swaged and the as-aged specimens showed a higher possibility of the adiabatic shear band formation because of the abrupt drop of shear stress between the maximum shear stress and the final fracture points and because of the radical reduction of shear strain at the maximum shear stress point. The observation of the deformed areas of the dynamically fractured torsional specimens revealed that the shear deformation was homogeneously distributed in a wide area in the as-sintered and the as-heat-treated specimens, whereas it was concentrated on the central area of the gage section in the as-swaged and the as-aged specimens. This torsional behavior correlated well with the shear stress-shear strain curves, suggesting that the torsional Kolsky bar technique is a good tool for helping evaluate the possibility of the adiabatic shear band formation. (C) 1998 Elsevier Science S.A. All rights reserved.