Evidence for strength degradation of polycrystalline oxide fibers by stress corrosion from coating decomposition products is reviewed. More data on Strength degradation during fiber coating is presented. Models for stress corrosion are applied and discussed. The stress that drives corrosion is most likely thermal residual stress between grains in the polycrystalline fibers. The observed temperature dependence of stress corrosion is too strong to be controlled by bulk gas diffusion or
Knudsen diffusion, but is consistent with control by strongly adsorbed surface active species.