The mechanical response of a Uranium-Niobium alloy: A comparison of cast versus wrought processing

A rigorous experimentation and validation program is being undertaken to develop "process aware" constitutive models that elucidate the fundamental mechanisms controlling plasticity in uranium-6 wt.% niobium alloys (U-6Nb). The first alloy is a "wrought" material produced, by processing a cast ingot via forging and rolling into plate. The second material investigated is a direct cast U-6Nb alloy. The purpose of the investigation is to determine the principal differences, or more importantly, similarities, between the two materials due to processing. It is well known that parameters like grain size, impurity size and chemistry affect the deformation and failure characteristics of materials. Metallography conducted on these materials revealed that the microstructures are quite different. Characterization techniques including tension, compression, and shear testing were performed to quantify the principal differences between the materials as a function of stress state. Dynamic characterization using a split Hopkinson pressure bar in conjunction with Taylor impact testing was conducted to derive and thereafter validate constitutive material models. The primary differences between the materials will be described and predictions about material behavior will be made.