Dynamic fracture of tungsten base heavy alloys

摘要

A recently developed short beam experimental technique has been applied to the characterization of the mode I dynamic fracture toughness (KId) of a commercial tungsten base heavy alloy (w/o-90W-7Ni-3Fe). The specimens were taken from a cylindrical swaged alloy bar and tested at a typical loading rate of the order of 10~6 MPa m~(1/2)/s. Three different crack orientations (one longitudinal and two radial) were investigated. The KId values obtained for the three crack orientations are compared with the corresponding values obtained under quasi-static loading conditions (KIc). Our results show that the dynamic fracture of heavy alloys is both an isotropic and rare sensitive. For specimens containing radial cracks (LR, RR), the dynamic fracture toughness is higher that its static counterpart. By contrast, for longitudinal cracks (RL), the dynamic fracture toughness is lower than the static one. Also, for radial cracks, both the (average) static and the dynamic fracture toughness are higher than in the longitudinal orientation. These new results about the anisotropy of the dynamic fracture toughness of the heavy alloys are reported and correlated with metallographic and fractographic examinations.