Abstract: The permeation curves of hydrogen in ferritic-austenitic duplex stainless steel have been electrochemically determined.The apparent diffusivity of hydrogen depends on the austenite content(f_γ)at room temperature,D=(0.27+0.9/f_γ~2)(10~(-10)cm~2/s).It is simply verified that hydrogen in ferritic-austenitic duplex stainless steel diffuses in “series-connection” form through both ferrite grain and austenite grain.The apparent diffusivity is D=D_αD_γ/(f_α~2D_γ+f_γ~2D_α),where D_α,D_γ are diffusivity of hydrogen in ferrite grain and austenite grain respectively,f_α,f_γ are volume fraction,in turn,of ferrite grain and austenite grain.

Key words: hydrogen, diffusion, duplex stainless steel