Abstract

The purpose of this research is to examine the performance of tungsten heavy alloy (WHA) susceptible to adiabatic shear failures and to identify the microscopic findings of shear band and its effect on the engineering behavior. Experimental results show that the binder-phase (Fe-Ni) and tungsten particles (W) have the high work-hardening rate at low-strain-rate compression (10-3 /sec). Thermal softening behavior is dominant at high-strain-rate (> 103 /sec), and this material is relatively insensitive to strain rate in the range of 3000 - 5000 /sec. The microscopic analysis by SEM reveals that most fractures in the shear band are intergranular where the Fe-Ni matrix has the least resistance to fracture. Transgranular fracture is also observed, but not significantly. With the constant strain rate, no shear band was observed under 30% compressive strain, whereas the extensive shear band was formed at the 50% strain with significant crack formation along the shear band zone and extends through the specimen thickness forming a cone shape inclined at an angle 40° to 50° to the loading direction. The measured surface temperature of the 40%-strained specimen is approximately 250 °C using high speed infrared temperature technique. A significant decrease in the ultrasonic velocities is measured with extension of the shear band.

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