Development of an Online IR-Thermography based Non-Invasive Technique to Detect and Estimate Iron in Galvannealed IF Steel Sheet

Galvannealed IF steel sheet is medium carbon steel sheet coated with zinc on both sides by continous hot dipped process. Immediately as the strip exits the coating bath, the zinc coating is subjected to an in-line heat treatment that converts the entire coating to a zinc-iron alloy. Conversion to the alloy results in a non-spangle matte finish which makes the sheet suitable for painting after fabrication. After post painting with proper selected primers and paints, the combined paint/galvannealed coat-ing offers excellent resistance to peeling and/or blis-tering of the paint in addition to long lasting corrosion resistance compared to conventional galvanized sheet.