The permeation of T in the 2.25Cr-1wt%Mo steel was measured by using unoxidized samples at temperatures of between 673 and 773K. It was found that the apparent activation energy was equal to 39.14kJ/mol. After steam oxidation at 755K and 0.2MPa for one month, the T permeation rate decreased by a factor of about 150, relative to that for the clean metal.

T.A.Renner, D.J.Raue: Nuclear Technology, 1979, 42[3], 312-9