摘要
采用腐蚀挂片实验对304L奥氏体不锈钢在80～135℃下2%～20%(质量分数)硝酸溶液环境中的腐蚀行为进行评价,并结合扫描电镜和金相显微镜分别对金属试样表面的微观腐蚀形貌和晶间腐蚀深度进行分析。结果表明,304L不锈钢的腐蚀速率随着温度的升高或硝酸浓度的增大先是缓慢增大而后急剧增大,腐蚀类型逐渐由均匀腐蚀转变为晶间腐蚀;304L不锈钢在硝酸蒸汽中的腐蚀受温度和硝酸浓度的影响程度高于其在硝酸水溶液中的腐蚀,在硝酸蒸汽中更易发生晶间腐蚀,且蒸汽中的晶间腐蚀程度明显较水溶液中的严重;随着腐蚀的加剧,304L不锈钢表面出现了晶粒破碎和脱落,导致材料发生不同程度的腐蚀减薄,这表明表面晶粒强度明显变差,且与内部相邻晶粒间的结合力显著减弱。
Corrosion behavior of 304 L stainless steel was investigated in the liquid and steam of2%～20%（mass fraction） nitric acids at 80～135 ℃ by coupon immersion test. The surface morphology of specimens after corrosion test and the depth of intergranular corrosion were examined by SEM and metallographic microscope, respectively. Results showed that the corrosion rate of 304 L stainless steel first increased slowly and then increased sharply with the increase of temperature or nitric acid concentration.Correspondingly, the corrosion form of the steel converted from uniform corrosion to intergranular corrosion. The influence of temperature and nitric acid concentration on the corrosion of 304 L stainless steel in nitric acid steam was higher than that in nitric acid solution, while the steel is more likely suffered form intergranular corrosion in nitric acid steam. The degree of intergranular corrosion in nitric acid steam was more serious than that in nitric acid solution. With the increase of corrosion, breaking and falling off of grains on the surface of 304 L stainless steel occurred, resulting in thinning in thickness of the material.
作者
赵小燕
刘希武
崔新安
于凤昌
ZHAO Xiaoyan; LIU Xiwu; CUI Xin＇an; YU Fengchang(Luoyang R＆D Center of Technology Sinopec Engineering （Group） CO., LTD., Luoyang 4 71003, China)
出处
《中国腐蚀与防护学报》
CAS
CSCD
北大核心
2018年第5期455-462,共8页
Journal of Chinese Society For Corrosion and Protection
基金
中石化科研项目(315108)~~
关键词
奥氏体不锈钢
硝酸
过钝化态
晶间腐蚀
austenitic stainless steel
nitric acid
transpassive state
intergranular corrosion
作者简介
赵小燕，女，1981年生，硕士生，高级工程师;通讯作者崔新安，E-mail：cuixa．lpec@sinopec．com，研究方向为金属材料腐蚀与防护
