Both hot rolled steel and cold rolled steel start out in essentially the same way and both can have the same grades and specifications. But cold rolled steel undergoes additional processing steps, resulting in improved properties that can be exploited for different applications. Each type of steel has its advantages and disadvantages and costs for the two types of steel are also different.
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How It&#;s Made
Both cold rolled and hot rolled steel start out as large steel slabs or billets cast from hot liquid metal. The billets are then heated, eventually reaching over °F. At this high temperature, they are easily flattened into a long sheet using a set of rollers, and then wound up into large coils. To make bars or plates, the heated billet is rolled to the desired thickness and cut into sections before cooling.
Both cold rolled and hot rolled steel start out as large steel slabs or billets cast from hot liquid metal. The billets are then heated, eventually reaching over °F. At this high temperature, they are easily flattened into a long sheet using a set of rollers, and then wound up into large coils. To make bars or plates, the heated billet is rolled to the desired thickness and cut into sections before cooling.
As the rolled or cut steel cools to room temperature, it shrinks slightly, making the final dimensions of each piece less exact and the edges somewhat rounded. The surface is slightly rough and covered in scale. At this point, hot rolled steel products are ready for shipment, and require no further treatment.
Cold Rolling Processes
But cold rolled steel products are destined for further processing after the steel has cooled. Cold rolling is most often used to decrease the thickness of plate and sheet metal in the manufacturing stage. This &#;cold forming&#; occurs either by re-rolling at around room temperature and then coiling into sheet, or else drawing into bars or tubes. Additional steps such as drawing, grinding or turning create the desired finished product.
But cold rolled steel products are destined for further processing after the steel has cooled. Cold rolling is most often used to decrease the thickness of plate and sheet metal in the manufacturing stage. This &#;cold forming&#; occurs either by re-rolling at around room temperature and then coiling into sheet, or else drawing into bars or tubes. Additional steps such as drawing, grinding or turning create the desired finished product.
Work hardening of the metal at room temperature increases its hardness and yield strength by introducing crystalline defects, but also may cause internal stresses that must be relieved by heating, or else the final product may warp.
Finishing Touches
Cold rolled or cold formed steel has a smooth, shiny finish with an oily texture that is free of rust or scale so it can easily be painted or chromed. The dimensions of the final product are more precise and square, with a sharper edge, and cold rolled steel sheet can hold tighter tolerances than hot rolled when machined or otherwise fabricated.
Cold rolled or cold formed steel has a smooth, shiny finish with an oily texture that is free of rust or scale so it can easily be painted or chromed. The dimensions of the final product are more precise and square, with a sharper edge, and cold rolled steel sheet can hold tighter tolerances than hot rolled when machined or otherwise fabricated.
In general, cold rolled and cold formed steel costs more than hot rolled steel because of the extra processing steps.
Industrial Metal Supply stocks hot rolled steel in the form of structural shapes, bar, sheet or plate, as well as cold rolled steel structural shapes, sheet and plate.
Steel is a versatile material that&#;s widely used due to its strength, durability, and flexibility. Its demand is expected to grow by about 2.2% to reach 1 881.4 Mt in .
But before steel is used in various applications, it must undergo production. One of the ways to make steel is through hot rolling. Unlike unprocessed steel, hot-rolled steel displays greater workability and formability. This makes it easier to work with in consequent processing operations.
What Is Hot-Rolled Steel?
This form of steel is manufactured by heating it at extremely high temperatures and passing it through rolling mills machinery. The temperature used is usually above the material&#;s recrystallization temperature.
The hot-rolling process typically shapes the steel into various forms and thicknesses. Hot-rolled steel is commonly used in construction and manufacturing applications.
The Benefits of Hot-Rolled Steel
Opting for hot-rolled steel has a lot of advantages. Benefits include:
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Quality Performance
The hot-rolling process can refine the grain structure and remove inclusions or other defects. This increases the ductility of the material.
As a result, hot-rolled steel tends to have improved strength and toughness. These improved properties are beneficial for applications where you need high mechanical performance.
Better Workability
Hot-rolled steel has improved workability. The high temperatures during the hot-rolling process make the steel more pliable and easier to form and shape.
Minimal Internal Stress
The gradual cooling process of hot-rolled steel during production helps to minimize internal stresses. As a result, the material is more stable and uniform. This improved stability and uniformity can increase the durability and performance of the final product.
Economical
The hot-rolling process requires less energy as the metal has a lower resistance to deformation at high temperatures. This can result in lower production costs. What&#;s more, hot-rolled steel tends to be cheaper.
How Hot Rolling Is Done?
The steps involved in the hot rolling process are:
Step 1: Heating
Heat the steel ingots or billets to a temperature above their recrystallization temperature &#; about 1,700 degrees Fahrenheit or higher.
Step 2: Rolling Mill Machine
Pass the heated steel through a rolling mill machine. The machine reduces its thickness and shapes it into the desired form. This process results in increased dimensional accuracy and reduced surface defects.
Step 3: Compression
After shaping the material in the rolling mill machine, it then undergoes compression by a series of rollers. The rollers apply pressure on the steel, reducing its cross-sectional area. This increases the material&#;s length and decreases its thickness.
Step 4: Cooling
The hot-rolled steel is then cooled using air or water. This helps prevent deformation and reduce its hardness.
Access High-Quality Hot Rolled Steel
To form quality hot-rolled steel, you need premium hot-rolling mill machinery. At FENN, we engineer and manufacture custom rolling mill machines for various applications. Our goal is to ensure maximum efficiency in your production.
Have a need for a hot rolling mill? With over 120 years as the leading rolling mill manufacturer, we can help design and build the right machine to suit your application requirements. Consult with our experts or get a quote from FENN today! Contact .
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