Effect of the Microstructure of Inconel 600 HTMA on Susceptibility to Stress Corrosion Cracking on the Simulated Nuclear Power Plant Operating Conditions

다국어 초록 (Multilingual Abstract)

It has been known that Inconel 600 material having been used for long time as steam generator tubing is susceptible to various localized corrosion, such as pitting, stress corrosion cracking, fretting, denting, etc., in the nuclear power plant operating conditions. Of the localized corrosion. stress corrosion cracking (SCC), nowadays, is a dominant defect mechanism occurring in steam generator tubing of domestic as well as world wide nuclear plants. The susceptibility of Inconel 600 material to SCC has been reported to be very sensitive to its microstructure. In this study, the susceptibility of archive Inconel600 high temperature mill annealed(HTMA) tubing having been used in steam generators on the operating nuclear power plants in Korea was investigated by changing its microstructure in order to see the degree of the integrity of the tubing. Accordingto the results, the susceptibility ofthematerial to primary andsecondary water SCC(PWSCC and IGSCC) is very sensitive to the microstructure of even the as-received tubing material and also to the microstructure modified using additional heat treatments under a simulated nuclear power plant operating conditions. It was confirmed that the resistance of the lnconel 600 HTMA material to SCC can be improved much by modifying its microstructure using proper heat treatments.