焊接残余应力对316LN不锈钢应力腐蚀裂纹扩展速率的影响

核电站不锈钢管道焊接过程中引入的残余应力对焊接接头的应力腐蚀开裂性能有较大影响。本文针对一AP1000主管道316LN不锈钢焊接模拟件进行残余应力分析和应力腐蚀裂纹扩展速率测量,得到了焊后原始状态和去应力热处理状态的焊接热影响区材料在高温高压水中的应力腐蚀裂纹扩展速率。实验结果表明,焊接残余应力明显提高了热影响区的应力腐蚀裂纹扩展速率,且在含氢的压水堆一回路正常水化学下焊接残余应力的影响更加显著。

Effect of Welding Residual Stress on Stress Corrosion Crack Growth Rate of 316LN Stainless Steel

High residual stress introduced at the welding joint can affect the stress corrosion cracking (SCC) property remarkably.The SCC growth rates of specimens prepared from a 316LN stainless steel AP1000 primary pipe welding mockup were measured in high temperature and high pressure water.The results obtained from heat affected zone (HAZ) of the specimens show that the welding residual stress has significant effects on accelerating crack growth rate,and the stress-relieved specimen has lower crack growth rate than the after-welding specimen.The acceleration of crack growth rate by residual stress seems to be greater in normal hydrogenated PWR water chemistry.