STP1421

    Analysis of the Sources of Variation in the Measurement of Paint Creep

    Published: Jan 2002


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    Abstract

    Performance testing of coil coated steel sheet products usually involves the measurement of paint creep back from a sheared edge or scribe (ASTM D 1654-92) on samples subjected to accelerated and atmospheric exposure tests. Measurements of paint creep are used for screening paints, pretreatments, and inorganic coatings for use on steel sheets. Because these tests are used for product development and selection, it is important to have a clear understanding of the limitations and sensitivity of these destructive test methods. A measurement system analysis has been undertaken to determine the sources of variation in edge creep measurements. Coil coated Galvalume® sheet material tested in salt spray is the subject of this investigation. A method for measuring edge creep that will provide satisfactory repeatability and reproducibility in the measurement system is described. It was found that without rigorous attention to the measurement method, the measurement system could contribute to as much as 25% of the variation in the measurement of edge creep. It has been shown that the operator preparing the samples is not a significant factor influencing the extent of edge creep. However, edge creep can vary by up to 1 mm simply because the test panels were cut from different positions across the width and along the length of a coil.

    Keywords:

    corrosion, paint, edge creep, scribe creep, steel, galvanized, Al-Zn coated steel


    Author Information:

    McDevitt, ET
    Research Engineers, Bethlehem Steel, Homer Research Laboratories, Bethlehem, PA

    Friedersdorf, FJ
    Research Engineers, Bethlehem Steel, Homer Research Laboratories, Bethlehem, PA


    Paper ID: STP10891S

    Committee/Subcommittee: G01.04

    DOI: 10.1520/STP10891S


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