Cr-Mo-V鋼および2.25 Cr-1 Mo鋼の焼戻し脆化の新しい電気化学的評価手法

概要

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A nondestructive electrochemical method is developed for detection and evaluation of temper embrittlement of Cr-Mo-V Steel and 2.25 Cr-1 Mo steel. In this method, temper embrittlement can be detected and evaluated by the second peak of current density "I_<P2>" which appears in the anodic polarization curves measured in a calcium nitrate solution. In contrast to nonembrittled materials (couplings and de-embrittling heat-treated materials) which exhibited the dull and low second peak, the sharp and high second peak current appeared in the anodic polarization curves measured on embrittled materials. This increase in I_<P2> is caused by selective dissolution of embrittled (impurity-enriched) grain boundaries and that increase in I_<P2> has a good correlation with the shifts in FATT. Temper embrittlement can be nondestructively evaluated by I_<P2> measurements with high accuracy.
1991-05-25