ISO INTERNATIONAL STANDARD 12732 First edition 2006-09-15 Corrosion of metals and alloys - Electrochemical potentiokinetic reactivation measurement using the double loop method (based on Cihal's method) Corrosiondes métaux et alliages-Mesurage dela reactivation electrochimiquepotentiocinetiqueparla methodede la double boucle (dérivee dela méthodede Cihal) Reference number ISO12732:2006(E) Contents Page Foreword IV 1 Scope 2 Normativereference 3 Terms and definitions 4 Principle... 5 Apparatus 6 Test solutions 7 Testspecimen preparation. 8 Procedure 9 Metallographic inspection ... 10 Evaluationofresults 11 Test report.... Annex A (informative) Flushed port cell and flushed electrode holder... 9 standard hydrogenelectrode (SHE)... AnnexC (informative)Suggested methodfor sensitizingtest specimens... Annex D (informative) Correlation of I/l, with the degree of grain-boundary sensitization, Pa (ASTM G108), OGBA and QGBL 14 ili Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/lEC Directives, Part 2 The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent iv Corrosion of metals and alloys Electrochemical potentiokinetic reactivation measurement using the double loop method (based on Cihal's method) WARNING -This International Standard may involve hazardous materials, operations and equipment. It istheresponsibilityof whoeveruses thisstandardto consult and establishappropriate safetyand health practices,and determine the applicability of regulatory limitations prior to use. Scope This International Standard specifies the method for measuring the degree of sensitization (DOS) in stainless steel and nickel-based alloys using the Double Loop Electrochemical Potentiokinetic Reactivation (DL-EPR) test (based on Cihal's method). The method maybeusedforthe quantitative assessment of deleteriousthermal effects resultinginthe formation of alloy-element-depleted zones at grain boundaries or in the matrix. However, attention should be paid when testing heat-affected weld zones, due to possible non-uniform distribution of sensitized zones along the fusion lines. The results of thetest can be used as anindexto identifythe potential susceptibilityof stainless steel and but prediction of these corrosion modes depends on complementary specific testing. This International Standard describes the general methodology and, in Annex C, gives examples of suitable testexposureconditionsforspecificalloys. Normativereferences The following referenced documents are indispensable for the application of this document. For dated document (including any amendments) applies. IsO8044:1999,Corrosionofmetals andalloys-Basic termsand definitions Iso643:2003, Steels—Micrographic determination of the apparent grain size 3Terms and definitions For the purposes of this document, the terms and definitions in IsO 8044 and the following apply. 3.1 integrated charge charge measured during passivation (Op) and reactivation (Or), given by the time integral of current below the passivation and reactivation peak of the curve 1 Principle 4 Heat treatment (including welding) of corrosion-resistant alloys can lead to formation of particles, such as chromiumcarbideinthe caseof304SSor-phase(FeCrMo)induplex stainless steels.Thiswill leadtolocal depletion of alloying elements, unless replenished by matrix diffusion, the extent of which will be temperature dependent. This process is commo