The Stress Corrosion Cracking of U-Nb Alloys in Air

Stress corrosion cracking (SCO of uranium alloys has been studied by our department for several years. We have previously summarized the SCC behavior of U-7.5%Nb-2.5%Zr in air as a function of relative humidity (RH).¹  Other workers have dealt with the influence of aging time and temperature on the SCC of U-5%Nb²  and with the SCC of U-2.3%Nb in an aqeuous environment.³  Magnani⁴  found k_iscc to be 22MN m^-1.5 for gamma-quenched U-4.5%Nb exposed to 100% and 0 to 10% RH. The value of k_iscc was found to increase to 25.3 MN m^-1.5 for samples aged for 80 hours at 260 C. Koger⁵  showed that for U-6%Nb, the susceptibility to SCC increased with aging time up to about the maximum strength, but that overaged samples were resistant to SCC. This report summarizes the SCC behavior in air of 4 gamma-quenched uranium alloys: U-2.3%Nb,...