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Mill scale is formed on the outer surfaces of plates, sheets or profiles when they are being produced by rolling red hot iron or steel billets in rolling or steel mills. Mill scale is composed of iron oxides mostly ferric and is bluish black in color. It is usually less than a millimetre thick and initially adheres to the steel surface and protects it from atmospheric corrosion provided no break occurs in this coating. Because it is electro-chemically cathodic to steel, any break in the mill scale coating will cause accelerated corrosion of steel exposed at the break. Mill scale is thus a boon for a while until its coating breaks due to handling of the steel product or due to any other mechanical cause. It is a nuisance when the steel is to be processed. Any paint applied over it is wasted since it will come off with the scale as moisture laden air get under it. Thus mill scale has to be removed from steel surfaces by flame heating, acid pickling or grit/sand blasting. All tedious operations wasteful of energy. This is why shipbuilders used to leave steel delivered freshly rolled from mills out in the open to allow it to 'weather' till most of the scale fell off due to atmospheric action. Now a days most steels mills can supply their produce with mill scale removed and steel coated with shop primers over which welding can be done safely.
Wiki User
∙ 14y ago
Wiki User
∙ 12y agomill scale of formed by oxygen reacting with the iron in ferrous metals, much like rust however this proces is sped up by heat
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What are the industrial uses of mill scale apart from cement production?
mill scale is used in making flux for welding electrode coating . mill scale is used for making iron oxide used in thermit welding by heating and converting in rotary kiln. mill scale is used as iron source in ferro alloy production yogendra Dhingra E.Mail: yogee46@gmail.com
Is mill scale hazardous?
On the MSDS sheet it is not considered a carcinogen.
Why drilling with vertical drill machine is more efficient than lathe machine?
For simple drilling, the vertical drill press is faster to use.
What type of mill is Sutter's Mill?
gravel
Why does hot rolled steel have mill scale?
Hot roll steel has a oxidised mil scale on the surface of the steel as it forms in the upper heat ranges from mixing with oxygen at a steel mill. Upon slow cooling, scale oxides will form a scale mainly of a type of iron oxide(s) usually of 3 distinct layers. This mil scale has a ability to be somewhat porous and can retain some moisture and is more noble in galvanic charges and at some times will potentially cause the underlying steel to corrode. The scale is not uniform in nature and can be loose in some areas and tighter in other areas and can pose a problem for people that want to paint or coat over it. The scale should be removed prior to any painting or TIG welding. Scale can be removed with various acid pickling type applications, flame treating, and mechanical blast or abrasion methods and then the freshly exposed cleaned surface of the reactive steel surface should be then protected from forming a fast acting blush rust.
How do you separate silica from mill scale?
what is the price of mill scale?
How can mill scale be removed?
Mill scale can be removed by sandblasting utilising high air pressure sandblasting equipment.
What are the industrial uses of mill scale apart from cement production?
mill scale is used in making flux for welding electrode coating . mill scale is used for making iron oxide used in thermit welding by heating and converting in rotary kiln. mill scale is used as iron source in ferro alloy production yogendra Dhingra E.Mail: yogee46@gmail.com
What is the stowage factor of mill scale?
0.38m3/ton
What are the applications of mill scale?
Mill scale by itself is not useful in the steel industry and is often discarded or recycled. Visual artists use it because it produces apparently random patterns.
What color is mill scale after it is hot rolled?
http://site2.wikianswers.com/templates/images/saveBtn_enable.gif?v=48569 The color of mill scale after it is hot rolled is bluish black.
Is mill scale hazardous?
On the MSDS sheet it is not considered a carcinogen.
What can Mill Scale be used for outside the Steel Industry?
In the production of cement.
What is the density of mill scale?
between 2.4 and 2.8 Tm/m3
Why is it considered essential to removed millscale pior to painting?
Mill scale must be removed prior to painting because any breach in the mill scale will cause moisture to get beneath it, causing it to flake off. If there is paint on top of it, and moisture gets below the paint and the scale, both will peel and flake off because the paint is adhering to the mill scale, not the underlying metal surface. Paint should always be applied only over a clean, sound surface.
What is the difference between mill scale iron ore fines?
mill scale fines are generated during hot rolling of cast ingot and it can be removed by pickling operation. iron ore fines are naturally available on iron ore and genetared during loading and grinding
How is mill scale packaged for export shipments?
mill scale is usually shipped without any packing, in bulk if the shipment is done in a chartered vessel. however, it is also being loaded directly into containers for shipment. If the customer insists, it can be packed in 1.2 MT Jumbo bags and then stuffed into the container for shipment.
