核级316NG控氮奥氏体不锈钢的局部腐蚀行为

Localized Corrosion Behavior of Nuclear Grade Nitrogen-Containing Austenitic Stainless Steel 316NG

采用电化学测试法、点腐蚀试验法、盐雾腐蚀试验法和慢应变速率测试法,分别对比研究了核级316NG控氮奥氏体不锈钢和321奥氏体不锈钢的局部腐蚀行为,并利用扫描电子显微镜、光学显微镜等分别观察腐蚀后不锈钢的表面形貌。结果表明:316NG和321不锈钢晶间腐蚀再活化率分别为3.83%和4.47%,点腐蚀速率分别为10.74g/(m2·h)和45.97g/(m2·h),盐雾腐蚀速率分别为2.14×10-2 g/(m2·h)和12.32×10-2 g/(m2·h),应力腐蚀开裂敏感指数分别为0.078和0.10;316NG不锈钢中N和Mo元素提高了其耐局部腐蚀性能,因此其耐局部腐蚀性能均优于核电站结构材料321不锈钢的。

The localized corrosion behavior of nuclear grade nitrogen-containing austenitic stainless steel 316 NG was studied in comparison with austenitic stainless steel 321 by electrochemical method,pitting corrosion testing,salt spray testing and slow strain rate testing（SSRT）,respectively.The surface morphology of the stainless steel after corrosion was observed by optical microscopy and electron scanning microscopy.The results show that for stainless steels 316 NG and 321,the rates of reactivation were 3.83%and 4.47%,the pitting corrosion rates were 10.74g/（m2·h）and 45.97g/（m2·h）,salt spray corrosion rates were 2.14×10-2 g/（m2·h）and 12.32×10-2 g/（m2·h）,and the sensitivity indexes of SCC were 0.078 and 0.10.The localized corrosion resistance of stainless steel 316 NG was better than that of stainless steel 321 because of the existence of Mo and N in the stainless steel 316 NG making localized corrosion resistance improve.