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Title: METHODS TO CALCULATE CORROSION RATES FOR ALLOY 22 FROM POLARIZATION RESISTANCE EXPERIMENTS

Authors:
Publication Date:
Research Org.:
Yucca Mountain Project, Las Vegas, Nevada
Sponsoring Org.:
USDOE
OSTI Identifier:
888865
DOE Contract Number:
W-7405-ENG-48, DE-AC08-91RW00134
Resource Type:
Conference
Resource Relation:
Conference: 2006 ASME Pressure Vessels and Piping Conference, Vancouver, July 2006
Country of Publication:
United States
Language:
English

Citation Formats

L. L. Wong, S. I. Martin, R. B. Rebak. METHODS TO CALCULATE CORROSION RATES FOR ALLOY 22 FROM POLARIZATION RESISTANCE EXPERIMENTS. United States: N. p., 2006. Web.
L. L. Wong, S. I. Martin, R. B. Rebak. METHODS TO CALCULATE CORROSION RATES FOR ALLOY 22 FROM POLARIZATION RESISTANCE EXPERIMENTS. United States.
L. L. Wong, S. I. Martin, R. B. Rebak. Sun . "METHODS TO CALCULATE CORROSION RATES FOR ALLOY 22 FROM POLARIZATION RESISTANCE EXPERIMENTS". United States. doi:. https://www.osti.gov/servlets/purl/888865.
@article{osti_888865,
title = {METHODS TO CALCULATE CORROSION RATES FOR ALLOY 22 FROM POLARIZATION RESISTANCE EXPERIMENTS},
author = {L. L. Wong, S. I. Martin, R. B. Rebak},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Apr 30 00:00:00 EDT 2006},
month = {Sun Apr 30 00:00:00 EDT 2006}
}

Conference:
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  • The general corrosion rate may be measured using immersion tests or electrochemical tests. Electrochemical tests are fast and can be used for a rapid screening of environmental effects such as temperature and electrolyte composition. Electrochemical tests are described in ASTM standards G 59 and G 102. The basis of these tests is to calculate the resistance to polarization (R{sub p}) in a voltage vs. current plot and to convert these values to corrosion rates using Faraday's law. Commercial software can calculate the corrosion rate based on inputs from the operator. This paper discusses three ways of calculating the corrosion ratemore » (Methods 1, 2, and 3) based on a fixed set of acquired data of voltage vs. current. It is concluded that the way the corrosion rate is calculated does not greatly impact the absolute value of the corrosion rate. Variations in the acquired data (current, potential) from one experiment to another seem more important than the manner in which data is fitted with the R{sub p} slope.« less
  • In its current design, the high-level nuclear waste containers include an external layer of Alloy 22 (Ni-22Cr-13Mo-3W-3Fe). Since over their lifetime, the containers may be exposed to multi-ionic aqueous environments, a potential degradation mode of the outer layer could be environmentally assisted cracking (EAC). The objective of the current research was to characterize the effect of applied potential and temperature on the susceptibility of Alloy 22 to EAC in simulated concentrated water (SCW) using the slow strain rate test (SSRT). Results show that Alloy 22 may suffer EAC at applied potentials approximately 400 mV more anodic than the corrosion potentialmore » (E{sub corr}).« less
  • When metallic plates are welded, residual tensile stresses may develop in the vicinity of the weld seam. Processes such as Low Plasticity Burnishing (LPB) and Laser Shock Peening (LSP) could be applied locally to eliminate the residual stresses produced by welding. In this study, Alloy 22 (N06022) plates were welded and then the above-mentioned surface treatments were applied to eliminate the residual tensile stresses. The aim of the current study was to compare the corrosion behavior of as-welded (ASW) plates with the corrosion behavior of plates with stress mitigated surfaces. Immersion and electrochemical tests were performed. Results show that themore » corrosion resistance of the mitigated plates was not affected by the surface treatments applied.« less
  • The polarization resistance method utilized for determination of instantaneous corrosion rates of metals is reviewed. The fundamental assumptions in electrode kinetics that govern the technique are restated. Error producing factors such as high excitation voltage amplitude, insufficiently slow scan rate or inadequate polarization hold period, high solution resistance, presence of competing reduction-oxidation reactions, and non-uniform current and potential distributions are discussed with the goal of defining conditions and circumstances where these complicating factors are important.
  • The effects of electrolyte composition and oxide film age on the crevice corrosion properties of alloys 625 and 22 were studied at temperatures ranging from 60 to 95 C in concentrated chloride electrolytes. Critical potentials were determined using conventional current density thresholds and comparisons were made between 625 and 22 on the basis of these critical potentials. Air aged 22 specimens exhibited the highest resistance to crevice corrosion at 95 C in terms of critical crevice potentials, while freshly polished 22 exhibited the lowest resistance. Studies over the entire, temperature range showed that air aged 22 is more resistant tomore » crevice corrosion than air aged 625 as evidenced by higher critical crevice potentials. As the temperature was lowered from 95 to 8O C, critical crevice potentials for 22 either approached or exceeded experimentally determined Cr (Mo, Ni) transpassive potentials.« less