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Application of the EPR method to duplex stainless steels
Author(s) -
DuretThual C.,
Bonis M.,
Crolet J.L.
Publication year - 2001
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/1521-4176(200101)52:1<37::aid-maco37>3.0.co;2-f
Subject(s) - electron paramagnetic resonance , materials science , metallurgy , analytical chemistry (journal) , chemistry , physics , chromatography , nuclear magnetic resonance
The present study is aimed at defining appropriate testing conditions in view of using the EPR (Electrochemical Polarization Reactivation) method for detecting the sensitization of 22 and 25% Cr duplex stainless steels at an earlier stage than conventional methods. In addition to this high sensitivity, these testing conditions should also be easy to use, for being applied not only in the laboratory (for qualification purpose) but also on production site (for Quality Control purpose, if needed). Reliable results were obtained with the required sensitivity, so the method can be used to control base materials and weld areas. Detailed testing conditions are provided in this paper for both 22 and 25% Cr stainless steels. They are based on the double loop method, with sulphuric and hydrochloric acid mixtures as testing media. Among the electrochemical parameters investigated, the importance of the initial cathodic polarisation is particularly pointed out as well as the quality of surface preparation, for getting reproducible results. Now an important piece of work remains for determining acceptance threshold levels for specific applications, since these acceptance levels are dependent both on the material (detailed composition, fabrication mode) and on the expected service conditions.