316LN在模拟压水堆一回路异常水化学条件下的应力腐蚀敏感性研究

Study on Stress Corrosion Cracking Susceptibility of 316LN in Simulated Primary Loop of PWR Under Abnormal Water Chemistry Conditions

摘要: 采用慢应变速率拉伸试验（SSRT）法研究了氯离子(Cl^-)和溶解氧对316LN在模拟压水堆（PWR）一回路异常工况下的应力腐蚀开裂（SCC）的影响。结果表明：在饱和氧条件下，随着Cl^-浓度的增大，试样的延伸率降低，SCC敏感指数增大，当Cl^-浓度大于1 mg/L后开始萌生SCC裂纹；溶液除氧后，即使Cl^-浓度增大到10 mg/L也不会引发SCC裂纹。316LN的SCC裂纹萌生于表面的缺陷或贫Cr区，呈穿晶型向基体内扩展。

Abstract: It was studied that the effects of chloride ions and dissolved oxygen on stress corrosion cracking (SCC) behavior of 316LN stainless steel in simulated primary loop of pressure water reactor (PWR) under abnormal water chemistry conditions with slow strain rate test (SSRT) method. The results show that in saturated oxygen condition, the extension of specimens decreases gradually while the SCC sensitive index increases with the increase of chloride ions concentration. In addition, the samples will produce SCC in the case that the concentration of chloride ions is more than 1 mg/L. However, cracks are not initiated in de-aerated solution even if the concentration of chloride ions increases to 10 mg/L. The stress corrosion cracks of 316LN are initiated in defects or Cr-depleted zones at the surface and transgranularly propagates into the base metal.