Optical measurement of uniform and localized corrosion of C1018, SS 410, and Inconel 825 alloys using white light interferometry

• A 3D non-contact optical microscope delivered non-destructive surface measurements.
• Here, criteria are given to analyze metal surfaces using a Bruker Contour GT-K.
• Uniform corrosion rates were calculated from changes in height over time using VSI.
• Uniform corrosion rates measured by VSI were verified by weight loss analysis.
• Localized corrosion rates of pits were calculated directly from VSI data.

We describe the use of a vertical scanning interferometer (VSI) to quantitatively measure the uniform and localized corrosion rates of different metal alloys used in the oil and gas industry. Based on white light interferometry, the most significant advantage is the large field of view in combination with nanometer Z-resolution for fast and accurate surface measurements. Corrosion rates were calculated directly from VSI data and verified by weight loss analysis. We explored the quantitative impact of high temperature and high salinity on C1018, SS 410 and I-825 alloys. VSI data for uniform corrosion correlated well with data from weight loss analysis.

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