Creep Damage Evaluation of High-Temperature Pipeline in Power Plant by Using Ultrasonic Velocity Measurement and Hardness Test

J. Ocean Eng. Technol. 1999;13(3):92-99.

Hur, Kwang-Beom;Yoo, Keun-Bong;Cho, Yong-Sang;Lee, Sang-Guk;

초음파 음속 및 경도법에 의한 발전소 고온배관재의 크리프 손상평가

허광범;유근봉;조용상;이상국;

한국전력공사 전력연구원;한국전력공사 전력연구원;한국전력공사 전력연구원;한국전력공사 전력연구원;

Keywords: Creep, Creep Life Fraction, Ultrasonic Test, Hardness Test, Sound Velocity, High-Temperaature Pipeline

핵심용어: 크리프, 크리프 손상율, 초음파시험, 경도시험, 음속, 고온배관

Abstract

High temperature and pressure materials in power plant are degraded by creep damage, if they are exposed to constant loads for long times, which occurs in load bearing structures of pressurized components operationg at elevated temperatures. Many conventional measurement techniques such as replica method, electric resistance method, and hardness test method for measuring creep damgage have been used. So far, the replica method is mainly used for the inspection of high temperature and pressure components. This technique is, however, restricted to applications at the surface of the testpieces and cannot be used to material inside. In this paper, ultrasonic evaluation for the detection of creep damage in the form of cavaties on grain boundaries or intergranular microcracks were carried out. And the absolute measuring method of quantitative ultrasonic velocity technique for Cr-Mo material degradation was analyzed. As a result of ultrasonic tests for crept for specimens, we founded that the sound velocity was decreased as increase of creep life fraction(${phi}c$) and also, confirmed that hardness was decreased as increase of creep life fraction(${phi}c$).