Fe-Cr-Ni (AISI 304, AISI 321), Fe-Cr-Ni-Mn (21-6-9, 21-9-9), Fe-Cr-Ni-Mo (AISI 316L, AISI 316LN): H Diffusion and Permeation

The permeability, diffusivity and solubility of H in these stainless steels were measured by using a gaseous permeation technique at temperatures of between 200 and 430C. The results indicated that the permeability and diffusivity obeyed Arrhenius relationships, and were not affected by cold-working or heat-treatment. The values were affected by the alloy composition (tables 60 and 61).

X.Sun, J.Xu, Y.Li: Materials Science and Engineering, 1989, A114, 179-87

Table 60

Diffusion Parameters for H in Stainless Steels at 200 to 430C

Steel	Do (m2/s)	E (kJ/mol)
AISI 316L	4.79 x 10-7	51.59
AISI 316LN	4.33 x 10-7	50.99
21-6-9	2.49 x 10-7	51.15
21-9-9	6.33 x 10-7	54.99
AISI 304	6.43 x 10-7	53.40
AISI 321	4.61 x 10-7	53.79

Table 61

Permeation Parameters for H (0.1MPa) in Stainless Steels at 200 to 430C

Steel	Po (molH2/msMPa½)	E (kJ/mol)
AISI 316L	3.90 x 10-4	64.06
AISI 316LN	1.85 x 10-4	60.66
21-6-9	2.52 x 10-4	61.29
21-9-9	2.83 x 10-4	62.29
AISI 304	2.85 x 10-4	62.43
AISI 321	2.44 x 10-4	62.70