The Similarity between Inter Granular Cracking of Alloy 600 in Simulated Primary Water and High Purity Hydrogen Gas at High Temperature

摘要

Hump-SSRT tests of alloy 600(UNS N06600) have been carried out under simulated primary water and dry high purity hydrogen gas at the temperature ranging from 360 to 320°C. Inter Granular (IG) cracking is observed not only under simulated primary water but also under high purity hydrogen gas. Results show that 1) Some constant loading condition should be needed to get IG cracking under pure hydrogen gas, however activation energy of IG cracking under simulated primary water is almost same as activation energy of IG cracking under dry high purity hydrogen gas. 2) IG cracking area ratio of fracture surface increases with increasing hydrogen pressure under pure hydrogen gas. IG cracking ratio of PWSCC at 360 °C is almost same as IG cracking area ratio under pure hydrogen gas of 10MPa at 360 °C. According to these results, it is strongly suggested that the basic mechanism of PWSCC is one kind of hydrogen embrittlement. However, more details of the role of corrosion, surface condition and loading condition should be clarified in future.