Fracture of uranium alloys

Since the fracture of uranium and its alloys has received little emphasis in the open literature, the first objective of this paper is to review past and current research in this area. Fracture toughness (K/sub Ic/) values for uranium alloys are compared to those for frequently used structural materials, with emphasis placed on work relating fracture behavior to microstructure and tensile behavior. Recent investigations concerned with the prediction of K/sub Ic/ and the development of simple but reliable fracture toughness test methods are discussed. The second objective of the paper is to describe an investigation of the fracture behavior of U--3/4 Ti and U--2 1/4 Nb. The research pursued two goals: (1) Characterizing the alloys' fracture toughness in a variety of service environments: The effects of strain rate, temperature, and humidity upon the fracture toughness of U--3/4 Ti and U--2 1/4 Nb were measured. (2) Relating fracture toughness to microstructural conditions. The fracture toughness of U--2 1/4 Nb was significantly improved through careful heat treating. This improvement is related to microstructural changes produced in the alloy and correlated to changes in fracture mode. In addition, the effects of shear forming and hydrogen content upon the fracture behavior of U--3/4 Ti were investigated. (9 tables, 18 figures, 73 references) (U.S.)