A gaseous permeation technique was used to measure the H permeabilities and diffusivities of specimens, after various heat treatments (tables 74 and 75), at temperatures ranging from 210 to 430C. The results showed that the temperature dependences of the H permeabilities and diffusivities in the various alloys obeyed Arrhenius relationships over the studied temperature range. Also, the H permeation behavior was essentially independent of the heat-treatment conditions. That is, it was not significantly affected by the presence of ' precipitates in the alloys. The H permeation parameters of the Fe-based superalloys were essentially consistent with those of austenitic stainless steels. The transport of H in these face-centered cubic alloys was generally controlled only by the lattice diffusion of H.
J.Xu, X.K.Sun, W.X.Chen, Y.Y.Li: Acta Metallurgica et Materialia, 1993, 41[5], 1455-9
Table 74
Hydrogen Permeation Parameters for JBK-75 in Various Conditions
Treatment | o (mol/smMPa½) | Q (kJ/mol) |
cold-rolled to 75% deformation | 0.000427 | 61.77 |
ST (980C, 1h), WC | 0.000162 | 56.42 |
ST (980C, 1h), WC, aged (740C, 4h), AC | 0.001060 | 66.27 |
ST (980C, 1h), WC, aged (740C, 8h), AC | 0.000390 | 62.00 |
ST (980C, 1h), WC, aged (740C, 16h), AC | 0.000504 | 63.65 |
ST: solution-treated, WC: water-cooled, AC: air-cooled
Table 75
Hydrogen Diffusion Parameters for JBK-75 in Various Conditions
Treatment | Do (m2/s) | Q (kJ/mol) |
cold-rolled to 75% deformation | 4.17 x 10-7 | 50.23 |
ST (980C, 1h), WC | 1.81 x 10-7 | 45.74 |
ST (980C, 1h), WC, aged (740C, 4h), AC | 2.40 x 10-7 | 47.21 |
ST (980C, 1h), WC, aged (740C, 8h), AC | 3.24 x 10-7 | 49.18 |
ST (980C, 1h), WC, aged (740C, 16h), AC | 5.99 x 10-7 | 51.99 |
ST: solution-treated, WC: water-cooled, AC: air-cooled