双相不锈钢在含硝酸体系中的优选腐蚀行为研究

研究了双相不锈钢在氧化性的HNO3 HCl、HNO3 NaCl、HNO3 FeCl3 3种体系中两相的腐蚀差异．通过动电位极化实验，用SEM和EDS对表面形貌进行观测和两相的鉴别，发现奥氏体相是优先腐蚀的相，在HNO3 HCl和HNO3 NaCl中随着CL^-浓度的增加，两相的优选腐蚀更加明显。但在HNO3 ReCl3中。低浓度的FeCl3会掩盖两相的优选腐蚀，而高浓度的FeCl3不存在这种反常行为．

A STUDY ON THE SELECTIVE DISSOLUTION BEHAVIOR OF DUPLEX STAINLESS STEEL IN SYSTEMS CONTAINING NITRIC ACID

Duplex stainless steel is composed of ferritic and austenitic phases,which have different crystal structure and element component, thus in different solutions,ferrite and austenite demonstrate different dissolution rate,that is,selective dissolution. In this investigation, the potentiodynamic polarization experiment was carried in nitric acid and hydrochloric acid mixture, and mixture of nitric acid and sodium chloride,nitric acid and ferrite chloride as well. After the experiments,SEM and EDS were used to distinguish and analyze the morphology differences of the two phases. The results show that in the solutions containing nitric acid,adding hydrochloric acid and sodium chloride will enhance the selective dissolution of two phases, while adding low concentration of ferrite chloride will decrease the corrosion difference between ferrite and austenite,but the phenomena vanish with the increasing of the concentration of ferrite chloride.