Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions: Part 1—Mill-Annealed Condition

Alloy 22 (N06022) has been extensively tested for general and localized corrosion behavior both in the wrought annealed condition and in the as-welded condition. In general, the specimens for laboratory testing are mostly prepared from flat plates of material. It is important to determine if the process of fabricating a container will affect the corrosion performance of this alloy. Thus, specimens for corrosion testing were prepared directly from a fabricated full-diameter Alloy 22 container. Results show that both the anodic corrosion behavior and the localized corrosion resistance of specimens prepared from a welded container were the same as those from flat welded plates.

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Determination of Crevice Corrosion Susceptibility of Alloy 22 Using Different Electrochemical Techniques

MRS Proceedings ◽

10.1557/proc-1265-aa09-10 ◽

2010 ◽

Vol 1265 ◽

Author(s):

Mauricio Rincon Ortiz ◽

Martín A. Rodríguez ◽

Ricardo M. Carranza ◽

Raul B. Rebak

Keyword(s):

Crevice Corrosion ◽

Electrochemical Techniques ◽

Localized Corrosion ◽

Repassivation Potential ◽

Alloy 22 ◽

Cyclic Potentiodynamic Polarization ◽

Corrosion Susceptibility ◽

High Level Nuclear Waste ◽

High Level

AbstractAlloy 22 belongs to the Ni-Cr-Mo family and it is highly resistant to general and localized corrosion. It may suffer crevice corrosion in aggressive environmental conditions. This alloy has been considered as a corrosion-resistant barrier for high-level nuclear waste containers. It is assumed that localized corrosion may occurs when the corrosion potential (ECORR) is equal or higher than the crevice corrosion repassivation potential (ER,CREV). The latter is measured by means of different electrochemical techniques using artificially creviced specimens. These techniques include cyclic potentiodynamic polarization (CPP) curves, Tsujikawa-Hisamatsu electrochemical (THE) method or other non-standard methods, such as the PD-GS-PD technique.The aim of the present work was to determine reliable critical or protection potentials for crevice corrosion of Alloy 22 in pure chloride solutions at 90°C. Conservative methodologies (which include extended potentiostatic steps) were applied for determining protection potentials below which crevice corrosion cannot initiate and propagate. Results from PD-GS-PD technique were compared with those from these methodologies in order to assess their reliability. Results from the CPP and the THE methods were also considered for comparison. The repassivation potential resulting from the PD-GS-PD technique was conservative and reproducible, and it did not depend on the amount of previous crevice corrosion propagation.

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Anodic Behavior of Specimens Prepared From a Full-Diameter Alloy 22 Fabricated Container for Nuclear Waste

Volume 7: Operations, Applications, and Components ◽

10.1115/pvp2005-71176 ◽

2005 ◽

Cited By ~ 1

Author(s):

Kenneth J. King ◽

John C. Estill ◽

Rau´l B. Rebak

Keyword(s):

Corrosion Resistance ◽

Corrosion Behavior ◽

Nuclear Waste ◽

Localized Corrosion ◽

Anodic Behavior ◽

Corrosion Performance ◽

Flat Plates ◽

Annealed Condition ◽

Alloy 22

Alloy 22 (N06022) has been extensively tested for general and localized corrosion behavior both in the wrought and annealed condition and in the as-welded condition. The specimens for testing were mostly prepared from flat plates of material. It was important to determine if the process of fabricating a full diameter Alloy 22 container will affect the corrosion performance of the alloy. Specimens were prepared directly from a fabricated container and tested for corrosion resistance. Results show that both the anodic corrosion behavior and the localized corrosion resistance of specimens prepared from a welded fabricated container was the same as from flat welded plates.

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Alloy 22 Localized Corrosion Susceptibility In Aqueous Solutions Of Chloride And Nitrate Salts Of Sodium And Potassium At 110 - 150?C

10.2172/893568 ◽

2006 ◽

Author(s):

S Felker ◽

P Hailey ◽

T Lian ◽

K Staggs ◽

G Gdowski

Keyword(s):

Aqueous Solutions ◽

Localized Corrosion ◽

Alloy 22 ◽

Nitrate Salts ◽

Corrosion Susceptibility ◽

Sodium And Potassium

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Localized Corrosion of Alloy 22 in Sodium Chloride Solutions at Elevated Temperature

CORROSION ◽

10.5006/1.3280655 ◽

2005 ◽

Vol 61 (9) ◽

pp. 857-871 ◽

Cited By ~ 5

Author(s):

N. Priyantha ◽

P. Jayaweera ◽

G. R. Englehardt ◽

A. Davydov ◽

D. D. Macdonald

Keyword(s):

Elevated Temperature ◽

Sodium Chloride ◽

Localized Corrosion ◽

Chloride Solutions ◽

Sodium Chloride Solutions ◽

Alloy 22

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Localized Corrosion Susceptibility of Alloy 22 as a Waste Package Container Material

MRS Proceedings ◽

10.1557/proc-713-jj1.6 ◽

2002 ◽

Vol 713 ◽

Cited By ~ 4

Author(s):

Gustavo A. Cragnolino ◽

Darrell S. Dunn ◽

Yi-Ming Pan

Keyword(s):

Chloride Concentration ◽

Department Of Energy ◽

Localized Corrosion ◽

Waste Package ◽

Alloy 22 ◽

Microstructural Effects ◽

Anionic Species ◽

Corrosion Susceptibility ◽

High Level ◽

Increasing Temperature

ABSTRACTAlloy 22 is the material preferred by the U.S. Department of Energy for the waste package outer container for geological disposal of high-level radioactive waste at the proposed repository site in Yucca Mountain, Nevada. The susceptibility of Alloy 22 to localized corrosion is an important consideration in the evaluation of the waste package behavior and the assessment of the overall performance of the proposed repository. The effects of the environment chemical composition and temperature on localized corrosion susceptibility were examined by measuring the repassivation potential for crevice corrosion in chloride-containing solutions at temperatures ranging from 80 to 150°C. The effect of potentially inhibiting anionic species, such as nitrate, was also determined. In addition to the mill annealed material, tests were conducted on both welded and thermally aged material to evaluate microstructural effects related to container fabrication processes. The resistance of Alloy 22 to localized corrosion decreased with increasing temperature and chloride concentration. Welding and thermal aging also decreased the localized corrosion resistance of the alloy.

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Effect of Inhibiting Oxyanions on the Localized Corrosion Susceptibility of Waste Package Container Materials

MRS Proceedings ◽

10.1557/proc-824-cc1.7 ◽

2004 ◽

Vol 824 ◽

Cited By ~ 4

Author(s):

D.S. Dunn ◽

L. Yang ◽

C. Wu ◽

G.A. Cragnolino

Keyword(s):

Radioactive Waste ◽

Crevice Corrosion ◽

Localized Corrosion ◽

Uniform Corrosion ◽

Waste Package ◽

High Level Radioactive Waste ◽

License Application ◽

Alloy 22 ◽

Corrosion Susceptibility ◽

High Level

AbstractThe DOE is currently preparing a license application for the permanent disposal of high level radioactive waste at Yucca Mountain, Nevada. The proposed design of waste packages for the disposal of high level radioactive waste consists of an outer container made of Alloy 22, a corrosionresistant Ni-Cr-Mo-W alloy, surrounding an inner container made of Type 316 nuclear grade stainless steel. Under conditions where passivity is maintained, the uniform corrosion rate of Alloy 22 is slow and long waste package lifetimes are projected. However, the initiation of localized corrosion such as pitting or crevice corrosion may decrease waste package lifetimes. In this study the crevice corrosion susceptibility of Alloy22 was determined in chloride solutions with additions of oxyanions that are present in the groundwater at the potential repository site. When present in sufficient concentrations relative to chloride, nitrate, carbonate, bicarbonate, and sulfate inhibited pitting and crevice corrosion of Alloy 22.

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Effect of Weak Acid Additions on the General and Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions

MRS Proceedings ◽

10.1557/proc-1107-511 ◽

2008 ◽

Vol 1107 ◽

Cited By ~ 2

Author(s):

Ricardo M. Carranza ◽

C. Mabel Giordano ◽

Martín A. Rodríguez ◽

Raul B. Rebak

Keyword(s):

Organic Acids ◽

Crevice Corrosion ◽

Electrochemical Impedance ◽

Dissociation Constants ◽

Formation Constants ◽

Localized Corrosion ◽

Acid Dissociation ◽

Complex Formation Constants ◽

Chloride Solutions ◽

Alloy 22

AbstractElectrochemical studies such as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 (N06022) in 1M NaCl solutions at various pH values from acidic to neutral at 90°C. All the tested material was wrought Mill Annealed (MA). Tests were also performed in NaCl solutions containing weak organic acids such as oxalic, acetic, citric and picric acids.Results show that the CR of Alloy 22 was significantly higher in solutions containing oxalic acid than in solutions of pure NaCl at the same pH. Citric and Picric acids showed a slightly higher CR, and Acetic acid maintained the CR of pure chloride solutions at the same pH. Organic acids revealed to be weak inhibitors for crevice corrosion. Higher concentration ratios, compared to nitrate ions, were needed to completely inhibit crevice corrosion in chloride solutions.Results are discussed considering acid dissociation constants, buffer capacity and complex formation constants of the different weak acids.

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Evaluation of Corrosion Processes Affecting the Performance of Alloy 22 as a Proposed Waste Package Material

MRS Proceedings ◽

10.1557/proc-807-435 ◽

2003 ◽

Vol 807 ◽

Author(s):

Gustavo A. Cragnolino ◽

Darrell S. Dunn ◽

Yi-Ming Pan

Keyword(s):

Stress Corrosion ◽

Compact Tension ◽

Department Of Energy ◽

Localized Corrosion ◽

Chloride Solutions ◽

Waste Package ◽

Alloy 22 ◽

High Level ◽

Long Term Performance ◽

Term Performance

ABSTRACTThis paper presents recent work on evaluating localized corrosion and stress corrosion cracking, two corrosion processes that are important to the long-term performance of Alloy 22 (58Ni-22Cr-13Mo-3W-4Fe). This alloy is the material preferred by the U.S. Department of Energy (DOE) for the outer container of the waste package to be used in the proposed high-level radioactive waste repository at Yucca Mountain, Nevada. It was found that both welded and thermally aged materials are more susceptible to localized corrosion in chloride solutions at temperatures above 60 EC than the mill-annealed material. This observation suggests that welding and certain post-welding operations may decrease the estimated life of the waste packages. However, no stress corrosion crack growth was observed in concentrated chloride solutions and simulated, concentrated groundwater at 95 EC when precracked compact tension specimens were tested under both constant and cycling loading.

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