니켈 합금 모재 및 용접재의 일차수응력부식균열 균열성장속도 시험

Abstract

Alloy 600/182 with excellent mechanical/chemical properties have been utilized for nuclear power plants. Although both alloys are known to have superior corrosion resistance, stress corrosion cracking failure hasbeen an issue in primary water environment of nuclear power plants. Therefore, primary water stress corrosioncrack (PWSCC) growth rate tests were conducted to investigate crack growth properties of Alloy 600/182. To investigate PWSCC growth rate, test facilities including water chemistry loop, autoclave, and loadingsystem were constructed. In PWSCC crack growth rate tests, half compact-tension specimens were manufactured. These specimens were then placed inside of the autoclave connected to the loop to provide primary waterenvironment. Tested conditions were set at temperature of 360℃ and pressure of 20MPa. Real time crackgrowth rates of specimens inside the autoclave were measured by Direct Current potential drop (DCPD)method. To confirm inter-granular (IG) crack as a characteristic of PWSCC, fracture surfaces of testedspecimens were observed by SEM. Finally, crack growth rate was derived in a specific stress intensityfactor (K) range and similarity with overseas database was identified.