Abstract
Multi-layered metals are expected to be useful to prevent hydrogen embrittlement. Hydrogen permeation and embrittlement of a multi-layered dual phase stainless steel (DPS18) that is made of ferritic stainless steel (SUS444) and austenitic stainless steel (SUS316L) have been investigated. Hydrogen diffuses in a ferritic phase, where hydrogen diffusivity is large, around a austenitic phase in DPS18. Hydrogen embrittlement is occurred in DPS18 rather than SUS316L. As a result of discussion, necessary conditions to design a composite material that has high strength for hydrogen embrittlement were obtained as follows : (a) hydrogen solubilities are different between component materials ; (b) one phase has high resistance for a crack propagation under hydrogen environment ; (c) an aspect ratio is much larger than a ratio between hydrogen diffusivities in component materials.
