Investigation and Applications of Corrosion Evaluating Technologies for Stainless Steels

For meeting the requirements of product design,optimization of heat treatment and hot working process,welding technology and subsequent evaluation of weldment quality,as well as assessment of service applicability for different kinds of stainless steels,some evaluation technologies for stainless steels have been established in combination with the ordinary testing standards for localized corrosion,such as pitting corrosion,crevice corrosion,intergranular corrosion and stress corrosion cracking.The present paper summarizes the main measurement technologies and their applications.The contents are as follows: (1) to establish the critical pitting temperature (CPT) measurement and the technology for micro-pit control;(2) to check out the partitioning behavior of alloying elements between ferrite and austenite during solution treatment of duplex stainless steels at different annealing temperatures (1000-1300 ℃);(3) to apply the non-destructive electrochemical polarization reactivation (EPR) originally designed for austenite stainless steels to a series of duplex stainless steels;(4) to clarify the relationship between the precipitation kinetics of secondary phase induced by lower temperature treatment (300-1000 ℃) and the associated pitting and intergranular corrosion of stainless steels;(5) to apply the electrochemical impedance spectroscopy (EIS) technology to assessing the intergranular corrosion behavior in complex microstructures;(6) to found the crevice corrosion temperature (CCT) method and its application.