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M4bu>: m ^TOM/US Agreement for Cooperation EURAEC Report No. 1665 prepared by SERAI Société d'Etudes, de Recherches et d'Applications pour l'Industrie, ¡Wir» Brussels - Belgium 0! ilPIllIL fCïî**iefitíU *itt*i Eurotom Contract No. 089-62- RSîAi'l'Î „ Paper presented at the 3rd International Congress on Metallic corrosion iiailliiiBllí;MMcOTr -USSR- M°>,6·25- ' w?iiiiS!iiiSSil siile «τ« ¡ι aw! ** Jr'fp f* UppÍ$$#!# LEGAL NOTICE fpjli This document was prepared under the sponsorship of the Com­ mission of the European Atomic Energy Community (Euratom) in pursuance of the joint programme laid down by the Agreement for Cooperation signed on 8 November 1958 between the Goverment of the United States of America and the European Atomic Energy Community. f'ÎBÏF if'" í t^TtfOini^ It is specified that neither the Euratom Commission, nor the Governmen„ *■ t of. th. e Unite. d- States~ , thei· . r contractor.iirusm oxJu.i'r anMy í person SMlj.rfíPf. acting on their behalf: ii»Miticijf^Ïlutffri"j',-j hrjfct Ij'itrJiiattíiílC¿ilttiUanitijiltí¿Hfl üñ ' 'l'ititi^^■1Γ'*:?!^·^1'''"1*^^*ι'Γ^Β**ίΐίί^' Make any warranty or representation, express or implied, with res­ or usefulness of the information that the use of any information, apparatus, method, or process disclosed in this document may not infringe privately owned rights; or Assume any liability with respect to the use of, or for damages M3 ¡II '■; This report is on sale at the addresses listed on cover page 4 ili I at the price of FF 4.— FB 40.— DM 3.20 Lit. 500.— Fl. 3. M5Í' EUR 2857.e CORROSION OF STAINLESS STEELS IN HIGH TEMPERATURE WATEB AND STEAM by M. WARZEE*, W.R. RUSTON*, P. de DORLODOT*, J. HENNAUT* and J.-Ph. BERGE** * SERAI ** EURATOM European Atomatic Energy Community - EURATOM EURATOM /US Agreement for Cooperation EURAEC Report No. 1665 prepared by SERAI - Société d'Etudes, de Recherches et d'Applications pour l'Industrie, Brussels (Belgium) Euratom Contract No. 089-62-7 RDB Paper presented at the 3rd International Congress on Metallic Corrosion, Moscow - USSR, May 16.25, 1966 Brussels, December 1966 -14 Pages - 6 Figures - FB 40 The corrosion of stainless steels in steam increases regularly between 200 and 300° C. This is not so in water: there, corrosion as function of tempera- EUR 2857.e CORROSION OF STAINLESS STEELS IN HIGH TEMPERATURE WATEB AND STEAM by M. WARZEE*, W.R. RUSTON*, P. de DORLODOT*, J. HENNAUT* and J.-Ph. BERGE** * SERAI ** EURATOM European Atomatic Energy Community - EURATOM EURATOM/US Agreement for Cooperation EURAEC Report No. 1665 prepared by SERAI - Société d'Etudes, de Recherches et d'Applications pour l'Industrie, Brussels (Belgium) Euratom Contract No. 089-62-7 RDB Paper presented at the 3rd International Congress on Metallic Corrosion, Moscow - USSR, May 16.25, 1966 Brussels, December 1966 - 14 Pages - 6 Figures - FB 40 The corrosion of stainless steels in steam increases regularly between 200 and 300° C. This is not so in water: there, corrosion as function of tempera- EUR 2857.e CORROSION OF STAINLESS STEELS IN HIGH TEMPERATURE WATER AND STEAM by M. WARZEE*, W.R. RUSTON*, P. de DORLODOT*, J. HENNAUT* and J.-Ph. BERGE** * SERAI ** EURATOM European Atomatic Energy Community - EURATOM EURATOM/US Agreement for Cooperation EURAEC Report No. 1665 prepared by SERAI - Société d'Etudes, de Recherches et d'Applications pour l'Industrie, Brussels (Belgium) Euratom Contract No. 089-62-7 RDB Paper presented at the 3rd International Congress on Metallic Corrosion, Moscow - USSR, May 16-25, 1966 Brussels, December 1966 - 14 Pages - 6 Figures - FB 40 The corrosion of stainless steels in steam increases regularly between 200 and 300° C. This is not so in water: there, corrosion as function of tempera- ture shows a marked maximum around 250° C for AISI 410 steel. For AISI 304 steel the maximum, which was not actually observed, must lie at a lower temperature. The quantity of dissolved metal is responsible for the maximum. It was shown that magnetite crystals grow out of the solution and that this redeposition may cause underestimation of corrosion values obtained in static autoclave tests. The observed phenomenon is of great technical signifi• cance because the cristallisation of magnetite from solution may cause mass transfer from cooler to hotter parts in nuclear reactors cooled with water and operating around 300° C. ture shows a marked maximum around 250° C for AISI 410 steel. For AISI 304 steel the maximum, which was not actually observed, must lie at a lower temperature. The quantity of dissolved metal is responsible for the maximum. It was shown that magnetite crystals grow out of the solution and that this redeposition may cause underestimation of corrosion values obtained in static autoclave tests. The observed phenomenon is of great technical signifi• cance because the cristallisation of magnetite from solution may cause mass transfer from cooler to hotter parts in nuclear reactors cooled with water and operating around 300° C. ture shows a marked maximum around 250° C for AISI 410 steel. For AISI 304 steel the maximum, which was not actually observed, must lie at a lower temperature. The quantity of dissolved metal is responsible for the maximum. It was shown that magnetite crystals grow out of the solution and that this redeposition may cause underestimation of corrosion values obtained in static autoclave tests. The observed phenomenon is of great technical signifi• cance because the cristallisation of magnetite from solution may cause mass transfer from cooler to hotter parts in nuclear reactors cooled with water and operating around 300° C. EUR 2857.e EUROPEAN ATOMIC ENERGY COMMUNITY - EURATOM CORROSION OF STAINLESS STEELS IN HIGH TEMPERATURE WATER AND STEAM by M. WARZEE*, W.R. RUSTON*, P. de DORLODOT*, J. HENNAUT*and J.-Ph. BERGE ** *SERAI ** EURATOM 1966 EURATOM/US Agreement for Cooperation EURAEC Report No. 1665 prepared by SERAI Société d'Etudes, de Recherches et d'Applications pour l'Industrie, Brussels - Belgium Eurotom Contract No. 089-62-7 RDB Paper presented at the 3rd International Congress on Metallic corrosion Moscow - USSR, May 16-25, 1966 SUMMARY The corrosion of stainless steels in steam increases regularly between 200 anil 300" C. This is not so in water: there, corrosion as function of temperature shows a marked maximum around 250" C for AISI 410 steel. For AISI 304 steel the maximum, which was not actually observed, must lie at a lower temperature. The quantity of dissolved metal is responsible for the maximum. It was shown that magnetite crystals grow out of the solution ami that this redeposition may cause underestimation of corrosion values obtained in static autoclave tests. The observed phenomenon is of great technical significance because the cristallisation of magnetite from solution may cause mass transfer from cooler to hotter parts in nuclear reactors cooled with water and operating around 300" C. CONTENTS INTRODUCTION 5 EXPERIMENTAL 6 RESULTS AND DISCUSSION 6 CONCLUSIONS 12 ACKNOWLEDGEMENT UO Corrosion of Stainless Steels in High Temperature Water and Steam (*) INTRODUCTION In many steam generators, particularly in nuclear power plants with boiling water reactors, the structural materials, generally stainless steels, are in contact with pressurised water at high temperature and with steam. It has been observed in the laboratory that marked differences in corrosion behavior appear when the stainless steels are exposed either to water, to wet steam or to superheated steam. Among the factors which may influence the corrosion resistance towards water or steam in the one or the other way, the surface preparation of the specimens was found to be of considerable importance. These observations have been published elsewhere |1 to 5 | and only the principal results are repeated here: — In pressurised water, between 200 and 300° C, AISI 304 steels having undergone a mechanical surface treatment (f.i. milling) corrode verv much quicker than the same steels from which the cold worked surface lavers were removed by electrolvtic polishing prior to the test. The corrosion rates at 300" C, measured bv the so-called "hvdrogen diffusion" method (**) are 0.003 mg.dnr-.hr~1 for electrolytically polished specimens, and 0.008 mg.dm"2.hr_1 for milled specimens respectively after 1000 hours. This effect is much less marked for ferritic steel AISI 410 at 200° C and 250° C and it disappears in water at 300° C and 350° C. — In superheated steam, surface treatments producing cold work do not affect the corrosion of AISI 304 and 410 steels between 200 and 300° C. However, at 400" C and still higher temperatures the beneficial effects of surface cold work are considerable. The explanation of these phenomena has already been published elsewhere [5-8]. The present paper deals with the comparison of the corrosion rates of stainless steels with identical surface treatments in water and in superheated steam at different temperatures. (*) Manuscript received on February 9, 1966. (**) First described by M.C. Bloom and al. Γ 6-7J. EXPERIMENTAL The results obtained with two types of stainless steel only are discussed here; the compositions of the specimens are shown by the following table: Origin and Steel Si S Ρ Cr trade mark C Mu Ni AISI 304 KRUPP 0.04 0.50 1.1 18.8 11.0 V2A­Supra Ha AISI 410 KRUPP 0.07 0.32 0.006 0.021 0.38 13.4 — V13F IIa The specimens are electrolytically polished in an aceto­perchloric acid bath and then rinsed with boiling water.