Hot Rolled Coils
Hot Rolled Coils
Hot rolling is a mill process which involves rolling the steel at a high temperature (typically at a temperature over 1700° F), which is above the steel’s recrystallization temperature.
When steel is above the recrystallization temperature, it can be shaped and formed easily, and the steel can be made in much larger sizes.
Hot rolled steel is typically cheaper than cold rolled steel due to the fact that it is often manufactured without any delays in the process, and therefore the reheating of the steel is not required (as it is with cold rolled).
When the steel cools off it will shrink slightly thus giving less control on the size and shape of the finished product when compared to cold rolled.
Uses
Hot rolled products like hot rolled steel bars are used in the welding and construction trades to make railroad tracks and I-beams, for example.
Hot rolled steel is used in situations where precise shapes and tolerances are not required.
| Specified width 0,8 < 1,5 |
Thickness Tolerance (a) For specified thickness (b-c-d) |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| ≥1,5 < 2,0 | ≥ 2,0 < 2,5 | ≥ 2,5 < 3,0 | ≥ 3,0 < 4,0 | ≥ 4,0 < 5,0 | ≥ 5,0 < 6,0 | ≥ 6,0 < 8,0 | ≥ 8,0 < 10,0 | ≥ 10,0 < 12,5 | _ | |
| 600 < 1200 | ± 0,13 | ± 0,14 | ± 0,15 | ± 0,16 | ± 0,18 | ± 0,20 | ± 0,22 | ± 0,25 | ± 0,27 | ± 0,30 |
| > 1200 ≤ 1500 |
± 0,14 | ± 0,15 | ± 0,15 | ± 0,18 | ± 0,20 | ± 0,22 | ± 0,24 | ± 0,26 | ± 0,28 | ± 0,31 |
| > 1500 ≤ 1800 |
± 0,15 | ± 0,18 | ± 0,20 | ± 0,22 | ± 0,24 | ± 0,25 | ± 0,26 | ± 0,29 | ± 0,32 | |
| > 1800 | ± 0,21 | ± 0,22 | ± 0,23 | ± 0,25 | ± 0,26 | ± 0,30 | ± 0,34 | ± 0,38 | ||
Width tolerances for coils and cut lengths (including descaled material), mill edge.
Dimensions and tolerances in millimeters
| Specified width | Tolerance |
|---|---|
| ≤ 1500 | +20 0 |
Width tolerances for coils and cut lengths
( including descaled material ) ,sheared edge, not resquared.
Dimensions and tolerances in millimetres
| Specified width | Tolerance |
|---|---|
| ≤ 1200 > 1200 ≤ 1500 > 15 |
+ 3 0 + 5 0 + 6 0 |
Length tolerances for cut lengths
( including descaled material ) ,not resquared.
Dimensions and tolerances in millimetres
| Specified width | Tolerance |
|---|---|
| ≤ 2000 > 2000 ≤ 8000 > 8000 |
+ 10 0 + 0,5% x length 0 +40 0 |
Hot Rolled “ HR ” Steel Sheet and Plate Applications
Steel Plate, or structural steel is simply steel sheet material that can be customarily cut and welded to develop a more elaborate product.
It is made by compressing multiple steel layers together into one; forming a plate of steel.
Some of the direct applications that benefit from hot rolled sheet and plate include :
• General fabrication
• Drums
• Containers
• Automotive panels
• Trailer siding
Hot Rolled Sheet and Plate Mechanical Properties
Hot rolled sheet and plate maintains many unique properties that separate it from other processes such as cold rolling.
The properties that are exclusive to the hot rolled steel manufacturing process include the following :
• Tensile Strength: 52,000 psi
• Yield Strength: 38,000 psi
• Brinell Hardness: 95
Manufacturing Process for Producing HR Steel Sheet & Plate
The HR steel square bar manufacturing process involves rolling steel at a temperature above the steel’s recrystallization temperature, which is around 1700° F.
Steel that is above the recrystallization temperature can be shaped and formed much more easily than colder steel, and the steel can start in much larger sizes.
The process to create hot rolled steel sheet and plate produces a more ductile steel with a rough surface finish that can be difficult to machine.
The cost is usually much less than a similar cold rolled steel product.
HR Steel Sheet & Plate Advantages
Hot rolling usually uses large ingots and large reduction rolling, which not only
improves production efficiency, but also creates conditions for increasing rolling speed and achieving continuous and automated rolling process.
Some of the other benefits associated with hot rolled steel square bar include :
• Increased malleability
• Numerous applications
• Less expensive than cold rolling
• High rate of production
Cold vs Hot Rolled Steel Sheet and Plate
The main differences between hot rolled and cold rolled steel comes down to specific manufacturing processes.
Hot rolling refers to processing done with heat, while cold rolling refers to processes done at or around room temperature.
Although these techniques affect overall performance and application, they should not be confused with formal specifications and grades of steel, which relate to metallurgical composition and performance ratings.
Both hot rolled steel and cold rolled steel start out in largely 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 can also vary widely.
Hot Rolled Steel Sheet and Plate Characteristics
Hot rolled steel plate and sheet typically requires much less processing than cold rolled steel, which makes it a lot cheaper.
However, since hot rolled steel can cool at room temperature, it’s free from internal stresses that can arise from quenching or work-hardening processes.
HR steel sheet and plate can be identified by the following characteristics :
• A scaled surface—a remnant of cooling from extreme temperatures
• Slightly rounded edges and corners for bar and plate products (due to shrinkage and less precise finishing)
• Slight distortions, where cooling may result in slightly trapezoidal forms, as
opposed to perfectly squared angles
Our Steel division is a leading provider of hot rolled steel sheet and plate materials in numerous shapes and sizes that are based on your project’s exact specifications.
Production Process
Hot rolled coils are manufactured using a continuous casting process or by reheating and rolling semi-finished steel slabs or billets. The steel is heated above its recrystallization temperature, which makes it more malleable. It is then passed through a series of rolling mills that gradually reduce the thickness of the steel and shape it into coils.
Properties and Characteristics
Hot rolled coils have specific properties that make them suitable for various applications. They typically have a rough, scaled surface due to the oxidation that occurs during the hot rolling process. The coils have a wider tolerance range for thickness and width compared to cold rolled coils, making them suitable for applications that do not require precise dimensions.
Versatility and Applications
Hot rolled coils find applications in a wide range of industries. They are commonly used in construction for manufacturing structural components, such as beams, columns, and channels. They are also utilized in the automotive industry for manufacturing vehicle frames, chassis, and other structural parts. Hot rolled coils are further processed to produce various steel products, including sheets, plates, pipes, and tubes.
Advantages
Hot rolled coils offer several advantages over other steel products. They have a higher strength-to-weight ratio, making them ideal for applications that require structural integrity and load-bearing capacity. The hot rolling process can enhance the mechanical properties of the steel, such as improved toughness and ductility. Hot rolled coils are generally more cost-effective compared to cold rolled coils due to the simpler production process.
Surface Treatment and Finishing
The rough, scaled surface of hot rolled coils may undergo surface treatment processes to improve their appearance and enhance their corrosion resistance. These treatments can include pickling, oiling, or applying protective coatings to the coils, depending on the desired application.
Quality Control
Hot rolled coils undergo strict quality control measures to ensure they meet industry standards and customer requirements. The mechanical properties, dimensions, surface quality, and chemical composition of the coils are tested and monitored throughout the production process.
Surface Treatment and Finishing
The rough, scaled surface of hot rolled coils may undergo surface treatment processes to improve their appearance and enhance their corrosion resistance. These treatments can include pickling, oiling, or applying protective coatings to the coils, depending on the desired application.
Quality Control
Hot rolled coils undergo strict quality control measures to ensure they meet industry standards and customer requirements. The mechanical properties, dimensions, surface quality, and chemical composition of the coils are tested and monitored throughout the production process.
Sustainability
Hot rolled coils can be recycled and reused, contributing to the sustainability of the steel industry. At the end of a product’s life cycle, steel scrap from hot rolled coils can be collected, melted down, and used to produce new steel products, reducing the need for virgin steel production and conserving natural resources.
Market Demand
The demand for hot rolled coils is influenced by factors such as construction activity, infrastructure development, manufacturing needs, and economic conditions. The construction, automotive, and manufacturing industries are major consumers of hot rolled coils, driving the market demand for these steel products.
Hot rolled coils are versatile and widely used in various industries due to their strength, cost-effectiveness, and suitability for structural applications. Their properties, surface treatments, and adherence to quality control measures ensure their reliability and performance. The ability to recycle hot rolled coils further contributes to the sustainability of the steel industry.
Billet steel serves as a crucial intermediate product in the steel manufacturing process. Its versatility and ability to be further processed make it an essential raw material for a wide range of steel products. The quality control, size consistency, and sustainable nature of billet steel contribute to its widespread use in the construction, manufacturing, and infrastructure sectors.