It was found that, at temperatures ranging from 90 to 330C, the temperature dependences of H diffusivity, permeability and solubility in the 0.2C-13Cr martensitic stainless steel could be described by:
D (m2/s) = 2.82 x 10-7exp[-34.36(kJ/mol)/RT]
P (mol/msMPa½) = 6.98 x 10-5exp[-43.93(kJ/mol)/RT]
S (mol/m3MPa½) = 2.48 x 102exp[-9.57(kJ/mol)/RT]
In the present temperature range, the H permeability in martensitic alloy steels was about an order of magnitude lower than that in -Fe, but was 1 to 3 orders of magnitude higher than in austenitic stainless steels. The H diffusivity was 2 to 4 orders of magnitude lower than in -Fe, and was 2 to 3 orders of magnitude higher than in austenitic stainless steels. In the martensitic alloy steels, the increased C content and the existence of retained austenite could result in a decrease in H diffusivity, but would have little effect upon the H permeability.
J.Xu, X.Z.Yuan, X.K.Sun, B.M.Wei: Scripta Metallurgica et Materialia, 1993, 29[7], 925-30
Table 63
Diffusivity of H in Fe-0.003C-5.58%Cr
Temperature (C) | Dlattice (cm2/s) | Doverall (cm2/s) |
640 | - | 1.8 x 10-4 |
545 | - | 1.4 x 10-4 |
450 | 1.8 x 10-4 | 1.1 x 10-4 |
350 | 1.7 x 10-4 | 9.9 x 10-5 |
250 | 1.0 x 10-4 | 5.8 x 10-5 |
200 | 7.8 x 10-5 | 3.5 x 10-5 |
120 | 5.2 x 10-5 | 3.0 x 10-5 |
103 | 3.9 x 10-5 | 2.3 x 10-6 |
80 | - | 7.0 x 10-6 |
50 | - | 2.3 x 10-6 |
30 | - | 1.8 x 10-6 |