When we are looking at steel goods, mechanisms or structures, we rarely think about how metal is made for them.

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Like any other stage of steel production, the rolling process includes different methods to produce rolled steel.

Globally, rolled steel can be hot rolled and cold rolled. Hot-rolled steel is thought to account for up to 80% of global commercial production of rolled steel. We will talk about it.

Metallurgy starts from raw materials such as iron ore and coke. When it comes to conventional technology, they are used to produce iron at blast furnaces (BF). The iron is then used to make steel and semi-finished steel products such as slabs, blooms, round or square billets, and beam blanks. In some cases, this production excludes a BF process. For this purpose, electric arc furnaces (EAF) are used, where ferrous scrap and direct reduction iron (DRI) are used as feedstock.

Although many global producers sell slabs and square billets, these products cannot be used directly to manufacture cars, machinery, goods or steel structures. Semi-finished products should be further processed at rolling mills, where rolled steel of the target shape, geometry, and physical and mechanical properties is produced.

All semi-finished steel products undergo hot rolling first. It is carried out at hot-rolling mills where a semi-finished product is subject to plastic deformation by passing between two rolls, as a result of which its initial shape changes. That said, the material temperature shall be above the steel recrystallisation temperature.

Roughly speaking, it should be rather soft to be deformed by rolls, like the dough under a rolling pin. Furthermore, the metal is very hot &#; in most cases its temperature at the beginning of rolling is above 1,100°&#; and its finishing temperature is at least 900°&#;. This is why such rolled steel is called hot-rolled.

• As a matter of fact, hot rolling is used to produce flat- and long-rolled steel:
• Plates or heavy plates from 4 to 350 mm in thickness
• Sheets from 1.2 to 4 mm in thickness
• Coils up to 25 mm in thickness
• Sections of simple shape &#; round, square, rebar, flat bar, and wire rod
• Structural shapes &#; rails, angles, H-beams, channels, special profiles, etc.

Hot-rolled steel is mainly produced at rolling mills consisting of stands. For example, hot-strip mills can consist of up to 15 "quarto" stands (i.e., each stand is complete with two pairs of rolls) and edgers to form the strip edges.

Hot-rolled plate production using slabs includes the following steps:

• Feeding slabs into reheating furnaces
• Reheating
• Feeding to the mill stands and rolling in several passes
• Levelling at a leveller
• Cooling at cooling beds
• In-line, non-destructive testing
• Trimming the longitudinal edge and ends, and cutting to length
• Finishing, check testing, acceptance, and marking

What are the advantages of hot rolling? If we wanted to process a cold steel slab into a flat product, we would hardly be able to succeed at it &#; such a slab is very hard, strong and thick even for specialised rolling equipment. Therefore, semi-finished products should be reheated first. Hot steel becomes plastic and easier to process. As a result, rolling mills help save time and efforts for the production of steel plates and strips.

In the CIS, finished hot-rolled plates are classified by:

• Accuracy (&#; &#; increased accuracy, B (&#;) &#; normal accuracy);
• Flatness (PO (&#;&#;) &#; extremely high, PV (&#;&#;) &#; high, PU (&#;&#;) &#; improved, PN (&#;&#;) &#; normal flatness);
• Edge type (NO (&#;&#;) &#; mill edge, &#; &#; trimmed edge), etc.

The main advantage of hot-rolled steel is that it costs less than cold-rolled steel. Therefore, it is widely used in applications where less attention is paid to the surface quality and super high-dimensional accuracy, e.g., to make support steel structures for large construction projects or in the engineering industry. Metinvest Group is a large producer of hot-rolled steel. The Group's enterprises in Ukraine and Europe are complete with rolling equipment that is capable of producing the widest range of hot-rolled flat products. For example, the plate mill at Azovstal Iron and Steel Works andthe plate mill at Ilyich Iron and Steel Works of Mariupol. The mills in Italy and the UK produce plates for construction, shipbuilding, and pipemaking, while HSM at Ilyich Iron and Steel Works of Mariupol, mill at Zaporizhstal, and Steckel mill at Ferriera Valsider (Italy) produce steel coils. It should be noted that Metinvest Group invested US$110 million in the modernisation of the HSM at Ilyich Steel between and .

To date, the typical hot-rolled flats production cycle involves reheating and rolling slabs. Strip-casting plants are becoming more commonly used by global steelmakers. In fact, this equipment combines steel casting and hot rolling into one production flow, omitting a semi-finished production stage. Such a technology makes it possible to achieve savings on utilities and to speed up the production process.

Although this technology is relatively young, Metinvest Group has been exploring the possibility of implementing it at one of its steel plants.

The production and applications of Hot-rolled Coils

Have you ever wondered how a beautiful car or your water heater is made? The answer starts in steel manufacturing mills in which raw steel is transformed to usable products that are used by different industries and present us a lot of useful products.

In this article we address one of the most popular types of steel coils that is used in factories to give you a general idea about hot-rolled coils.

What does Rolling Process mean?

&#;Rolling&#; is a very popular term in the metalworking world, it refers to a metal forming process in which a metal stock is passed between two rolls in order to reduce its thickness and get a uniform thickness.

Rolling is the initial process of all steel product manufacturing such as structural steel and coils.

Rolling mills can process steel quickly and convert semi-finished casting products including ingots, blooms, billets or slabs into finished products like beams, bars, or coils&#; etc.

What is the difference between Hot Rolling and Cold Rolling?

Rolling is classified according to the temperature of the metal being rolled.

Here we should introduce the Recrystallization term which is a process by which deformed grains are replaced by a new set of defect-free grains.

This process requires a particular temperature to occur which is called the recrystallization temperature.

While rolling, if the metal&#;s temperature was above its recrystallization temperature, then it is called a hot rolling process. and if it is under the recrystallization temperature then it is called a cold rolling process.

That is, hot rolling is a process done with heat, whereas cold rolling is done at or near to room temperature.

Prime steel and secondary steel can be either hot-rolled or cold-rolled including all steel grades and specifications.

It is obvious that some types of steel are more suitable for certain uses.

Using the suitable type of steel can save time and money and avoid the wastage of raw materials.

Hot-rolled steel:

Hot-rolled steel is a steel that had roll-passed at a very high temperature, approximately more than degrees Fahrenheit which is above the recrystallization temperature for most steel types.

The heat gives steel a workable starting form and makes it easier to shape.

Hot rolling starts with a large long steel called billet which is heated and sent to a large roll to flatten, then it is passed in a series of rolls keeping it&#;s high temperature until reaching to the final wanted dimensions.

Then steel sheets are spun into coils and left to cool.

For bars and beams steel is sectioned and cooled.

Hot rolling doesn&#;t give precise dimensions since steel shrinks while cooling, so the resulting steel is suitable for applications where minutely specific dimensions aren&#;t crucial, like railroads and constructions.

Hot rolling steel can be defined by these features due to shrinking and remnant of cooling:

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a scaled surface, slightly rounded edges and corners, and slight distortions

Advantages of hot rolling steel:

• Cost-efficiency because it requires much less processing than cold rolled steel.
• Free from internal stresses that arise while cooling since it left to cool at room temperature.
• Ideal for applications where accurate dimensions are not important as steel strength.

Hot-rolled Coils:

Hot-rolled coils are one of the flat steel products.

They are sheets of prime or second choice steel that are rolled in a hot steel mill into coils while they are very hot.

These coils are very common types of steel coils that form the base product for other steel coils like coated and galvanized coils and also used directly nearly in various industries and machinery, like construction, shipbuilding, automotive&#;etc.

Hot-rolled coils manufacturing process:

Hot-rolled coils production process goes into three main stages:

Heating stage:

A steel slab or billet is heated in a furnace to a very high temperature approximately degrees Fahrenheit which affects the properties of steel and dissolves the compound of carbon and nitrates that exist in steel.

Heating process makes the steel more malleable, making it easier to be rolled.

When the steel is taken out of the furnace and transferred to the rolling mill it reacts with oxygen and forms a flaky surface scale of iron oxides which reduce the quality of steel.

To remove this unwanted scale steel is sent through a mill scale cleanse and sprayed with high pressure water.

Rolling stage:

The cleansed steel is sent to a series of rollers consisting of four or five sets of rollers that reduce the thickness to approximately 1/10 of original thickness.

A vertical pressure is applied to control the width.

After that steel is trimmed and sent to another set of rollers to get the desired thickness and winded into coils while it is hot.

Cooling stage:

The flat rolled steel is passed under cooling sprays and left to cool at room temperature then it goes to coilers to obtain the final product.

The resulting hot-rolled coils can be delivered to steel manufacturers for further processing or directly to customers.

Hot-rolled coils applications:

As we mentioned before, hot-rolled coils are typically used in applications that don&#;t require a perfect surface finishing and where accurate dimensions are not critical to the project.

Hot-rolled coils are a good choice when tight tolerances are not so important, and when price is more important than precision.

They are a preference for steel companies and metalworking due to their malleability and cost-efficiency.

Hot-rolled coils have an appearance that distinguishes them over other coil types, they are darker gray and have a silvery blue, almost purple strip along both sides makes the steel&#;s surface appear as if it is still hot to the touch. 

This appearance makes hot-rolled coils the most commonly used type for art sculptures.

Common applications for hot-rolled coils include:

• Constructions.
• Railroads.
• Truck frames.
• Automotives.
• Guardrails.
• Steel doors,shelves and tanks.
• Shipbuilding.
• Gas containers.
• Pipes and tubes.

Hot-rolled coils for your project:

Our company imports prime and secondary steel hot-rolled coils directly from steel mills and delivers you high-quality hot-rolled coils at very good price.

Exanvil Gmbh offers specific requirements and specifications of coils and helps you to choose the best suited coil for end use.

coil&#;s length and size is available as you need, you will get your hot-rolled coils in size, characteristics and time you want it.

For small or large orders Exanvil Gmbh is ready to meet its customer needs.

Hot-rolled coils are indispensable steel products that we see their applications in everyday life from cars to beverage cans.

Contact us to discuss your requirements of ar steel grades. Our experienced sales team can help you identify the options that best suit your needs.