Cold rolled sheet is commonly known as 'white
steel'. This variety of sheet is produced by the cold rolling process.
The
cold rolled sheet has specific characteristics that are different from
the hot rolled steel sheet variety. This sheet has good formability and
mechanical properties. Cold rolled steel sheet serve as a major input in
a wide range of industries. Cold rolled steel sheets are supposed to
have good surface finish, high standards of heat treatment and has
thinner and better gauges. Cold rolled steel sheets are available since
many years and have been used in many applications. The cold rolled
sheets have been improvised over the years. The improvisation has been
in terms of:
- Shape
- Width
- Thickness
- Surface finish
This variety of steel is ideally used for coating purposes for
other different usages. The different industries wherein cold rolled
steel sheet is used are:
- Enamelware (porcelain-coating)
- Galvanizing (zinc-coating) industries
- Tin-coated food can (tin mill-black plate) industries
Specific features of Cold Rolled Sheets:
The cold rolled sheets are so designed that they have specific
attributes like :
- Deep drawability
- High strength
- Good magnetic properties
- High dent resistance
- Paintability
- Enamelability
- Formability
Manufacturing Process:
The cold rolled steel sheets are produced keeping in mind the end
usage. There are various factors that need to be kept in mind while
manufacturing the cold rolled steel sheet. The first step is the cold
reduction operation. This procedure not only makes the steel sheet
thinner but makes it harder, less ductile and very difficult to form.
After this the product is annealed, i.e., heated to high temperatures
hence making it very soft and formable. This unique combination of cold
reduction and annealing makes the steel refined which enables the
customer to get the desirable and unique forming properties. The main
feature of the cold reduction is to reduce the thickness of the hot
rolled coils which is not possible in the hot rolled state. It is
actually very important to maintain the uniformity in the sheet
thicknesses so that the sheet performs consistently when used by the end
user. There are other factors which needs to be taken care of in the
cold rolling process like, flatness-meaning deviation from a flat plane.
The flatness is maintained by the usage of very sophisticated strip
shape controlling technology. Surface finish is another attribute that
is taken care of during the cold reduction process.
The following are the different processes that are helpful in producing
high quality cold rolled sheet products, like-
- Hot strip mill processing variables
- Pickling practices
- Annealing practices
- Temper rolling practices
- Steel chemistry
- Cold-rolling mill practices
Application
- Oil barrels & containers
- Bicycles
- Refrigerators
- Automobiles
- Domestic Appliances
- Electronics & Electrical components
- Washing Machines & geyser
Types of Cold Rolled Steel Sheets:
The cold rolled steel sheets products are produced keeping in mind the
end usage of the product. Thus there are variants of cold rolled steel
sheets that are available. They are mentioned below:
- Cold Rolled Full Hard Sheet Steel
- Vitreous Enamel Sheet (Vitrenamel)
- Cold Rolled Motor Lamination Sheet
Cold Rolled Full Hard Sheet Steel:
These product mainly used in further application such as continuous
galvanizing. The following specifications should be mentioned while
placing an order:
- Dimensional tolerances
- The steel chemistry
- Sheet dimensions
- The metallurgical designation, i.e., Commercial Steel, Drawing
Steel, etc.
Vitreous Enamel Sheet (Vitrenamel):
This is a cold rolled steel sheet product processed with enhanced
qualities for porcelain enameling. Similar to the cold rolled steel
sheet, Vitrenamel Sheet can be ordered according to the specific needs.
Such enameled sheets are extensively used in door and cabinet laminates.
Cold Rolled Motor Lamination Sheet :
This specific kind of cold rolled steel sheet is made to be used for
electromagnetic core material for electrical equipment components. Such
sheets are generally used in generators, transformers, motors. The main
factor kept in mind while manufacturing this sheet is the core loss.
Core loss means the electrical loss in electrical equipment due to heat
generation by alternately magnetizing and demagnetizing the components.
The degree of the core loss is decided by the chemical composition of
the steel and the core material processing. Another factor is the
permeability, meaning the ease of magnetization.
