열처리된 SA508 합금에서의 초음파 비선형성 측정: 결정립과 석출물 영향

초록

In the present study, the influences of grains and precipitates of microstructural evolution on the ultrasonic nonlinearity have been experimentally investigated. The prior-austenite grain and precipitate size are controlled by the variation in austenitizing and tempering conditions in reactor pressure vessel materials of nuclear power plant, SA508 Gr.3 low alloys. The ultrasonic nonlinearity was found to have strong correlations with grains and precipitates since the ultrasonic nonlinear parameter β shows decrease trend with coarsening of grains and precipitates. Although the prior-austenite grain size increased, the β changed little due to the effects of subgrains, packets and laths. For the preciptate effects, the β decreased sharply due to decrease in Mo2C causing the coherency stain in addition to the precipitate size. The results in this study may provide a potential for characterizing the microstructural evolution, grains and precipitates, by measuring the ultrasonic nonlinearity.

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