DEVELOPMENT OF TECHNIQUES FOR ROLLING URANIUM METAL

Uranium can be rolled from cast metal or forged ingot to sheet satisfactory for cupping, deep drawing, and similar fabrication procedures by a combination of hot breakdown in the neighborhood of 600 deg C and warm finishing at 225 to 325 deg C. Sheet may also be obtained by hot rolling alone and by warm rolling alone, but the combination of hot and warm rolling afforded the best and most practical method to secure good quality sheet in the quantity required. The percent reduction by hot working does not appear to be critical, but at least 60% warm reduction is desirable to obtain complete and controlled grain size by recrystallization with high ductility and strength properties. Except for research investigation, rolling of uranium below 225 deg C is not recommended. Hot rolling of unplated uranium from the as-cast or as-forged surface is recommended, using a bath of 35% Li/sub 2/CO/sub 3/ plus 65% K/sub 2/CO/sub 3/ for a heating medium. No further preparation other than washing the salt from the hot rolled surface is required before warm rolling, and a bath of Meltemp No. 7 oil is recommended for warm rolling. Starting with an as-cast tensile strength averaging 60,000 psi, as-rolled sheet up to 230,000 psi was produced, with elongation averaging 5--8% and tensile to yield strength ratios averaging 75%. Uniform, equi-axed grains are produced upon annealing, and grain sizes can be controlled by choice of annealing temperature and time. (P.C.H.