Mechanical behavior of aged uranium-3/4 weight percent titanium alloy

Abstract

The mechanical behavior of the uranium-3/4 weight percent titanium alloy in the aged condition has been characterized by tension, notched tension, and compression tests. These tests were made over a temperature range of {minus}196{degree}C to 80{degree}C, at strain rates from .001 s{sup {minus}1} to 2000 s{sup {minus}1}. Metallography on selected samples using optical and scanning electron microscopes was used to identify fracture modes. Compression and smooth tensile tests showed a linear decrease in yield strength with increasing temperature, and for tensile tests, a linear decrease in ultimate tensile strength with increasing temperature. The corresponding tensile ductility was relatively constant at temperatures above 0{degree}C, then decreased rapidly with decreasing temperature. Notched tensile tests showed a ductile-to-brittle transition at about {minus}40{degree}C. SEM photographs showed a mixture of ductile-dimple fracture and brittle cleavage areas in all notched tensile sample fracture surfaces. Fracture surfaces on smooth tensile test samples showed a ductile-dimple structure at 80{degree}C, a primarily ductile-dimple structure with some long narrow cleavage facets at 24{degree}C, and a mostly cleavage structure at {minus}54{degree}C. The mechanical threshold stress model was fit to yield stress data and the parameters for an equation describing yield stress as a function of temperature and strain rate were determined.more » 15 refs., 32 figs., 4 tabs.« less