Mill scale is a by-product of the steel rolling process that forms a thin layer of oxidized metals. It can protect steel from corrosion but must be removed before painting or other treatments. Methods include chemical removal or weathering. Steel quality can vary based on production processes and materials used.
Mill scale is a very thin layer of brown to black material that forms when people pass steel through a hot mill to roll and shape it. Sheet metal companies usually use milling because it is cost effective and the rolling scale is an unwanted by-product of the process. There are several options for removing it to expose the clean underlying layer of metal so people can have it treated like painting to prepare it for use.
The composition of the mill scale includes a mixture of oxidized metals. It actually acts as a protective, keeping the underlying material safe from corrosion. However, as soon as it begins to crack, air and fluid can seep under the mill scale and damage the material underneath. Some factories immediately remove the scale in chemical toilets so their metal is ready to use, while others may allow the metal to weather out in an exposed area to encourage the scale to fall off.
People cannot apply paint and other treatments to the mill scale, as it will start to flake off, taking the treatment material with it. This leaves the steel under exposed. While removing mill scale can be time consuming and energy and personnel intensive, it is required before people can proceed to use steel in manufacturing processes. Another option is to use cold milled steel, where no oxidation occurs, leaving the metal surface clean and ready to use.
When people buy sheet metal for projects, they may find that it has a layer of mill scale because the company hasn’t treated it or hadn’t had a chance to withstand the elements. It’s important to remove this layer before proceeding with a project, either leaving the metal so the scale can flake off or dousing it in a material like vinegar to loosen the scale. Once the scale starts to come off, people can buff and polish to remove the last flakes of material and clean the metal.
Steel mills use a variety of processes to control the quality and composition of their product. Depending on how the company handles metals and the type of temperatures it uses, the final quality of steel products can vary greatly. Some steels are more elastic and robust, while others are very strong but brittle and cannot withstand shear or bending forces. Depending on what a company makes metal for, the composition of the scale can change as the company uses different materials in its steel production.
Protect your devices with Threat Protection by NordVPN
