Mechanical property evaluation of surface layer corroded in thermochemical-hydrogen-production process condition

Futakawa, Masatoshi  ; Kubo, Shinji  ; Wakui, Takashi*  ; Onuki, Kaoru; Shimizu, Saburo; Yamaguchi, Akihisa*

Micro-indentation technique was applied to evaluate the mechanical properties of corroded surface layers of Ni-alloy, 316SS, Ti and Ta, which were exposed into the corrosive gaseous environment consisting of HI+I+HO+H. The corrosion condition was chosen so as to simulate one of the environments in the thermochemical hydrogen production, IS process, where the degradation due to the corrosion attack by HI and the hydrogen embrittlement is a key issue from the viewpoint of material integrity. The micro-indentation tests using a spherical indenter and the inverse analysis with Kalman filter were performed to quantitatively estimate material constants of corroded surface layer. Ni-alloy exhibited good corrosion resistance and Ta was remarkably influenced by the hydrogen embrittlement.