A thermal outgassing method (t.o.m.) To measure the hydrogen diffusion coefficients in austenitic, austeno-ferritic and ferritic–perlitic steels

Abstract

A thermal outgassing method (T.O.M.) and a baking method have been applied to measure the hydrogen diffusion coefficient at high temperature (150–600°C) in an austenitic stainless steel (AISI A286), an austeno-ferritic stainless steel (Z2CND2205) and a ferritic–perlitic steel (FM35). The results obtained by the above mentioned methods are in good agreement with those measured by the permeation technique at high temperature. Furthermore, in the austeno-ferritic steel Z2CND2205 the inverse of the total hydrogen diffusion coefficient 1\\ D H( α+γ) is equal to f α \\ D H α + f γ \\ D H γ , where f α and f γ are, respectively, the volume fraction of α and γ phases and D H α and D H γ are the hydrogen diffusion coefficients for each phase.