Nonlinear Ultrasonic Technique for Evaluating Degradation of Dissimilar metal welds in Nuclear Facilities

Abstract

This study presents the nonlinear ultrasonic technique to evaluate structure health of nuclear facilities. Recently, a dissimilar welds cracking in the aging of nuclear power plant has become a big issue. For this reason, this study was performed for dissimilar welds composed of SA508 cl.3 low alloy steel, Inconel 82 weld, and AISI 316L stainless steel damaged by high temperature long-term aging. Structure health was evaluated through the measurement of nonlinear ultrasonic characteristic. Microstructural changes of material have an effect on nonlinear ultrasonic characteristic and generate second harmonics that is twice the fundamental frequency. Ultrasonic oblique incidence measurement technique was used to measure ultrasonic nonlinearity.