Internal Hydrogen Embrittlement of Gamma-Stabilized Uranium Alloys

Abstract

Abstract Relationships between the tensile ductility and fracture characteristics of as-quenched, gamma-stabilized uranium alloys (uranium-10 Wt% molybdenum, uranium-8.5 Wt% niobium, uranium-10 Wt% niobium, and uranium-7.5 Wt% niobium-2.5 Wt% zirconium), the hydrogen content of the tensile specimens, and the hydrogen gas pressure during the annealing at 850 C of the tensile test blanks prior to quenching have been established. For these alloys, the tensile ductility decreases only slightly with increasing hydrogen content up to a critical hydrogen concentration above which the tensile ductility drops to nearly zero. The only alloy not displaying this sharp drop in tensile ductility was U-7.5 Nb-2.5 Zr, probably because sufficiently high hydrogen contents could not be achieved under our experimental arrangements. The critical hydrogen content for ductility loss increased with increasing hydrogen solubility in the alloy. Fracture surfaces produced by internal hydrogen embrittlement do not resemble those produced by stress corrosion cracking (SCC) in aqueous environments containing chloride ions.