電気化学的手法によるW強化型9%Crフェライト系耐熱鋼のクリープ損傷評価

概要

論文の詳細を見る
In order to develop a methodology for creep damage evaluation of W alloyed 9%Cr ferritic steel KA-STBA29/KA-STPA29 (ASME T92/P92), which is the candidate material for an ultra-super-critical fossil power plant, changes in electrochemical property of the steel caused by creep have been investigated. Experimental results on electrochemical polarization measurements revealed that the peak current density"I_p", which appeared at a specific potential during potentiodynamic polarization measurement in 1N-KOH solution, increased with thermal aging and creep damage and reflected not only the thermal effect but also the stress effect on creep damage. The I_p value corresponded to the selective dissolution volume of precipitates (M_23C_6 and Laves phase) and the increase in the I_p due to creep damage reflected the increase in amount of chromium precipitated as Laves phase. It was also found that the difference in the I_p value between the as-tempered material and the creep damaged materials (ΔI_p) were uniquely correlated with a newly proposed parameter "t・F(T)・exp(-Q(σ)/RT)" irrespective of test conditions, which is the parameter based on Laves phase precipitation kinetics. On the basis of such correlation between ΔI_p and t・F(T)・exp(-Q(σ)/RT), the test temperature or the applied stress of the creep damaged materials can be nondestructively estimated by electrochemical polarization measurements.
社団法人日本材料学会の論文
2001-05-15