Cored wires are an essential part of the steel industry and can now be traded on Metalshub. Learn what types of cored wires are available on Metalshub and get insights in the history and current use of the materials here.
Widely used in the steelmaking process, cored wires have become indispensable in the steel industry. Helping maintain high speed in production and control the accuracy of the chemical elements in casting, are just some of the important qualities that cored wires possess.
The elements in cored wires vary from wire to wire, all depending on what exactly the user needs them for. However, one thing is for sure, cored wires have revolutionised the steel industry and made steel production a more efficient and accurate business.
The invention of cored wires
Cored wires entered the market in the 1970s. With industry machines developing, the focus was on ensuring the quality and cleanliness of the steel. In other words, figuring out how to quickly separate the molten steel from the impurities – also known as slag.
Here, the keyword is calcium.
Calcium creates a chemical reaction with the steel and the oxygen that the steel comes in contact with during oxygen furnace and electric arc furnace melting operations. This chemical reaction forms calcium aluminates. These aluminates help generate the formation of the slag quicker and turn solid at steelmaking temperature. This way, it becomes easier to separate the molten steel from the impurities.
However, adding calcium to the heat wasn’t easy, and many different ways were tested. The steel industry was looking for a more efficient process to enable higher and more constant results. This was the reason cored wires were invented. Even though cored wire let the way for a more efficient process, back then it wasn’t all that simple to use. In the early years, cored wire was delivered on wooden spools. It was necessary to not only have injection machines but also to have a complex technology for decoiling – such as e.g., turntables.
Cored wires in today’s steel industry
Today, cored wires aren’t delivered on a wooden spool anymore. Instead, what is being used in the steel mills are so-called “flipping coils”. Flipping coils enable an endless, waste-free consumption of an entire coil as the end of the coil in use relates to the beginning of the next coil. However, this set-up also requires adequate space in the steel mills to have two coils connected next to each other.
Just like back in the 1970s, today’s steel producers need injection machines and other technologies to add the cored wire into the heat of the molten steel. The equipment generally needed to guide the wire is a feeder machine and a wire guiding tube that leads to the ladle, which guides the wire into the heat. The distance between this tube and the bath surface should be as short as possible to enable a proper penetration through the slag. A guiding system from the coil into the feeder machine is another essential tool.
The most common cored wires
Calcium monosilicide (CaSi) cored wire is the most used cored wire quality in the steel industry. In the European steel industry, the most common wire diameter is 13 mm. However, 9 mm wire is used if technical reasons like high powder density of e.g., FeMnN or lower addition rates for pure calcium are requested by the user.
The specifications of cored wires
Cored wires don’t only contain different elements, they also come in many different sizes. So, to describe an entire cored wire coil specification, it’s important to know the following parameters:
Coils type
The coil type is defined by the producer and depends on the producer’s nomenclature (name of the product). It normally contains the powder content and encrypted information for dimensions and diameters.
Wire diameter
The wire diameter means the diameter of the wire itself. In the European steel industry, the most common diameter used is 13 mm followed by 9 mm. In the USA, 16 mm and even 21 mm are used.
Wall thickness
The wall thickness describes the sheath thickness used for the production of the wire. It is normally 0.4 mm, but can also be from 0.5 mm up to 1 mm.
Coil-Inner-Ø
This is the inner diameter of the finished coil and depends on the outer diameter of the production equipment where the wire is coiled during production.
Coil-Outer-Ø
Coil-Outer-Ø is the outer diameter of the finished coil and depends mainly on the pallet size, means of transport (truck or container), and on the steel mills’ space to place coils.
Coil height
The coil height means the width of the coil, from front face to front face. It depends on the width of the coiling equipment at the cored wire producer.
Wire length
The wire length means the total wire length of the finished coil after production.
Specific filling weight
The specific filling weight describes the powder content in g/m. It is important for the metallurgists and operators in the steel mill to calculate the wire length to be injected to meet their requirements.
Total filling weight
The total filling weight shows the powder weight of the entire coil.
Wire weight
The total wire weight shows the weight of the filling powder and sheath of the entire coil.
Gross weight
The gross weight is the wire weight plus the packaging weight (pallet and cage).
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