一方向凝固Ni基超合金のクリープに伴う電気化学的特性の変化と損傷評価

概要

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Changes in electrochemical properties of directionally solidified Ni-base superalloy CM 247 LC due to creep have been investigated. The electrochemical polarization technique has been applied to creep-ruptured and creep-interrupted specimens under various creep condition 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 increased with increased thermal history and showed a good correlation with Larson-Miller Parameter value. I_p and I_<pr> value reflected both a thermal aging effect and a stress effect, and increased with a creep life fraction. The increases in I_p and I_<pr> were mainly corresponded to increases in preferential dissolution rate of γ' phase at γ/γ' interface. This preferential dissolution was considered as a result from degradation of corrosion resistance of γ'phase at γ/γ'interface which may be attributable to creep damage accumulation. As a consequence, the creep damage in CM 247 LC can be quantitatively evaluated by the electrochemical technique.
社団法人日本機械学会の論文
1998-07-25