電気化学的手法を用いたガスタービン用Ni基超合金のクリープ寿命評価

概要

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In order to develop a creep life assessment technique for a directionally solidified Ni-base superalloy CM247LC used in advanced gas turbine blades, changes in electrochemical properties of CM247LC due to creep have been investigated. The electrochemical polarization technique has been applied to creep-ruptured and creep-interrupted specimens under various creep conditions in order to examine a detectability of creep damage. Experimental results on electrochemical polarization measurements revealed that the peak current density"I_p"and"I_<pr>"which appeared at a specific potential during potentiodynamic polarization reactivation measurements in dilute glyceregia solution linearly increased with a life fraction in early stage of the creep life (t/t_r=0.3). The increases in I_p and I_<pr> mainly corresponded to increases in preferential dissolution rate of γ' phase at γ/γ' interface. This preferential dissolution was considered as a result from change in chemical composition of γ'phase at γ/γ'interface which may be attributable to creep damage accumulation. As a consequence, the creep life fraction can be estimated with high accuracy by the electrochemical technique.
社団法人日本機械学会の論文
1999-05-25