초음파를 이용한 2.25Cr-1Mo 고온 구조재 열화ㆍ손상의 비파괴평가

다국어 초록 (Multilingual Abstract)

Ultrasonic is a powerful nondestructive technique for the purpose of microstructure evaluation and getting the information of material properties in services facilities. In this study, nondestructive evaluation for degraded structural materials used at high temperature by conventional L-wave and surface SH-wave is discussed. Sixteen kinds of 2.25Cr-1Mo steel specimens with different degradation levels which were prepared by the isothermal aging heat treatment at 650℃ were evaluated by ultrasonic nondestructive evaluation investigating the change of attenuation coefficient analyzed by spectral analysis. As carbide precipitation increase and spherodization near grain boundary of microstructure to aging degradation, attenuation coefficient had a tendency to increase as aging time. It was identified possible to evaluate degradation using the characteristics of surface SH wave. Most of all, frequency dependency of ultrasonic attenuation coefficient to aging degradation appeared prominently on the surface SH-wave. And it was also observed that the change of ultrasonic attenuation with aging time was more sensitive at high frequency region and surface SH-wave mode.

목차 (Table of Contents)

• Abstract
• 1. 서론
• 2. SH파 탐상의 특징
• 3. 실험
• 4. 결과 및 고찰
• 5. 결론
• 후기
• 참고문헌