Mill Scale
A flaky surface layer of iron oxides formed on hot-rolled steel during manufacturing processes.
Overview
Mill scale is a by-product of hot rolling steel, consisting primarily of iron oxides (wüstite, magnetite, and haematite). It forms as a thin, blue-grey, flaky coating on the surface of steel as it cools after being rolled at high temperatures. In the automotive supply chain, mill scale is relevant both as a surface condition to be managed on incoming steel and as a recyclable iron-rich feedstock for steelmaking and sintering processes.
Automotive Applications
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Properties
Category
Type
Iron Oxide By-product
Available Colors
Available Forms
Key Properties
- High iron oxide content
- Abrasion resistant
- Dense and brittle
- Recyclable feedstock
- Electrically conductive
Technical Specifications
Density
~5.0–5.7 g/cm³
Sustainability
Sustainability Rating
Mill scale is largely recycled back into steelmaking via sintering plants, reducing iron ore consumption and landfill waste.