FANG Yaohua Nanjing Institute of Chemical Technology
,
Nanjing
,
ChinaXU Yuan ZHANG Wenqi University of Science and Technology Beijing
,
Beijing
,
China FANG Yaohua Associate Professor
,
Dept.of Applied Chemistry
,
Nanjing Institute of Chemical Technology
,
Nanjing 210009
,
China
金属学报(英文版)
The corrosion behaviour and mechanism of superpure austenitic stainless steel 00Cr25Ni22Mo2N in urea processing environment was studied using metallography,SEM, TEM,SIMS and AES techniques.The results show that the gas extraction tube made of non-sensitized 00Cr25Ni22Mo2N steel suffered intergranular corrosion.Corrosive media penetrated not only into the tube wall through grain boundaries but also expanded from the boundary towards the interior of the grain.Neither depletion of Cr nor precipitates were found at the grain boundaries.However,P(and Si)was segregated at the grain boundaries to a great extent.Semiquantitative calculation indicates that the P content at the grain boundaries is about 25 wt-%,three orders of magnitude higher than the content within the grain.Sugges- tion is made that the potential difference between the grain and its boundary due to the segre- gation results in the observed intergranular corrosion.
关键词:
superpure austenitic stainless steel
,
null
,
null
方耀华
,
徐源
,
张文奇
金属学报
运用金相、电子显微镜观察及表面分析技术,研究了超纯奥氏体不锈钢00Cr25Ni22Mo2N制造的汽提管在尿素生产环境下的腐蚀形态和机理。结果表明,该钢种在生产条件下产生非敏化态晶间腐蚀,其特征是腐蚀介质不仅沿晶界向钢的内部渗入,而且同时向晶界的两侧扩展;晶界区磷的含量(约25％)比晶内高约三个数量级,由此造成的晶界与晶内在腐蚀电解质溶液中的电位差,是导致该钢种非敏化态晶间腐蚀的原因。
关键词:
超纯奥氏体不锈钢
,
intergranular corrosion
,
P(Si) segregation
