STP1086

    Effect of Ground-Water Composition on the Electrochemical Behavior of Carbon Steel: A Statistical Experimental Study

    Published: Jan 1990


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    Abstract

    Historically, the study of the effects of environmental variables on the corrosion behavior of metals has been performed by varying a single species at a time. At most, a two or three variable matrix of tests has been performed. In this study, a statistically designed matrix of tests was performed to examine the main-term effects and several two-factor interaction terms of 15 environmental variables present in ground-water solutions on the corrosion behavior of carbon steel. Cyclic potentiodynamic polarization experiments were performed to determine several characteristic polarization parameters. Regression analyses established which of the environmental variables had a statistically significant effect on each of the polarization parameters. The environmental variables were selected to simulate basalt rock ground-water solutions with the emphasis being the application of carbon steel as a high-level nuclear waste container (overpack). It was found that, to accurately describe the effects of ground-water variables, two-factor interaction terms were often as important, or more so, than the main-effect terms. A limitation of the technique is that, with the large concentration ranges used, the design concentrations could not be achieved due to ion interaction; this produced a correlation among factors in the regression model and inaccuracies in the predictions.

    Keywords:

    corrosion, potentiodynamic polarization, experimental design, regression analysis, main-effect, interactions, statistical test matrix, ground waters, pitting corrosion, high-level nuclear waste, carbon steel


    Author Information:

    Thompson, NG
    President and senior scientist, Cortest Columbus, Inc., Columbus, OH

    Beavers, JA
    President and senior scientist, Cortest Columbus, Inc., Columbus, OH


    Paper ID: STP26104S

    Committee/Subcommittee: G01.11

    DOI: 10.1520/STP26104S


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