Evaluation of material degradation of austenitic stainless steels based on nonlinear eddy current method

Uchimoto, Tetsuya*; Takagi, Toshiyuki*; Nemoto, Yoshiyuki  ; Takaya, Shigeru  ; Keyakida, Satoshi*

This paper discusses feasibility of non-linear eddy current method to evaluate material degradations of austenitic stainless steels associated with irradiation assisted stress corrosion cracking. For the purpose, tensile test at elevated temperature was conducted on materials simulating radiation-induced segregation, and non linear harmonic analysis of eddy current was carried out for the tensile test specimens. In addition, microstructure of magnetization of the tensile test specimens was observed by magnetic force microscopy. It was shown that non linear harmonics of eddy current is associated with the Cr depletion and Ni enrichment at grain boundary and intragranular phase transformation.