Steel has always been a very familiar material in our lives. Among them, hot-rolled steel and cold-rolled steel are the two most commonly used types of steel. However, not everyone knows about these two types of steel, nor is it clear which one should be chosen in construction. Therefore, in the following content, JWB will compare hot-rolled steel and cold-rolled steel so that people can understand clearly and make the right choice.
What is hot rolled steel and cold rolled steel?
Before comparing cold rolled steel and hot rolled steel, first we need to understand them. Specifically:
What is Hot Rolled Steel?
Hot Rolled Steel is a type of steel that has been made by rolling at high temperatures (up to 1000°F). This allows the steel to be formed and processed much better than untreated steel, making processing much easier and more convenient.
The process is as follows:
Raw materials are taken from the steelmaking plant and heated in a furnace, which usually reaches temperatures of 1000°C (the temperature at which steel recrystallizes).
These billets are then continuously rolled until they reach their final shape.
Advantages and Disadvantages of Hot Rolled Steel
– Advantages
The hot rolling method helps reduce the yield strength of the steel and increase its toughness. This makes the steel easier to bend, improving its ability to be formed and making the shape more precise.
When the steel is heated and continuously rolled, the molecules are more evenly distributed in the steel. This can eliminate or reduce the inhomogeneities within the steel.
The cooling effect also helps eliminate dimensional errors or completely fill holes in the steel surface caused by oxidation.
– Disadvantages
After hot rolling, the steel will enter a cooling phase at room temperature. During this cooling process, inhomogeneities may occur, resulting in excess stress in the finished steel. This is especially true for some steels with uneven cross-sections, such as rail steel, I-beams, etc.
The dimensional deviation (tolerance) of the finished steel will be between 2% and 5%.
Despite the good quality of the finished product, the surface of the steel is always covered with an oxide film (also called roll imperfections – this is formed after the hot rolling process). This is an oxide formed at high temperatures, which makes the finished product less aesthetically pleasing, but can be solved by some technical means, such as: deoxidation, grinding or sandblasting.
What is the use of hot rolled steel？
Due to the above characteristics, hot rolled steel products are best suited for structural components and can also be used in applications where high shape or tolerances are not required, such as:
Railway track steel;
Hot-rolled steel plates;
I-beams;
Truck chassis;
Automotive clutches;
wheels and rims;
Most compressor housings, etc.
Cold rolled steel
Cold-rolled steel is a general term for a type of steel that is processed at room temperature (i.e. steel that is processed at room temperature).
Cold-rolled steel (cold-rolled steel) is actually a type of steel that is rolled at a temperature much lower than hot rolling. Usually between 700 and 900 degrees Celsius. After rolling, cold-rolled steel will undergo other processes such as shearing, cutting, bending or flattening to produce high-strength and dimensional precision steel products.
Common cold processing processes include rolling, extrusion, deep drawing, bending, etc.
Please note that due to character limitations, some omissions may occur in the translation. If necessary, you can request supplements or corrections.
Advantages and Disadvantages of Folding Cold Rolled Steel
– Advantages：
The finished product strength and hardness of folded cold rolled steel is higher, usually 15-20% higher than hot rolled steel. This is achieved through the bending or processing steps of the steel.
For the yield strength of folded cold rolled steel, it is usually between 33ksi and 80ksi.
The elastic modulus of folded cold rolled steel can reach 29,000 to 30,000 ksi.
Folded cold rolled steel is used to manufacture finished products to higher precision standards. Because the processing steps are all carried out at room temperature, the steel does not shrink as it does during the hot rolling process.
Folded cold rolled steel has higher aesthetics and a very smooth surface because no oxide film is formed on the surface.
The quality of the finished products produced is always very consistent.
– Disadvantages：
Folded cold rolled steel may be more limited in its ability to bear loads in structures subject to bending and compression.
The finished product is usually limited to certain shapes, such as square, round, oval, rectangular, etc. This is because after the folding cold rolling step, the hardness and strength increase, but the toughness decreases. Therefore, the formability of folded cold rolled steel is much worse than hot rolled.
What is folded cold rolled steel used for?
Manufacturing household appliances
Furniture processing
Parts that require high aesthetics and high precision…
It is widely used for the manufacture of products that require high quality and good load-bearing capacity due to its excellent hardness, good toughness, high load-bearing capacity, easy welding and cutting.
What is the rolling process?
Rolling is a process that stretches the material through the friction between two rotating cylindrical rollers to reduce the thickness of the material. In this process, the two cylindrical rollers are connected by bearings and driven by a strong driving force.
The curling gap can be adjusted as needed. The curling gap is usually called the gap of the curling.
This is one of the important steps in metal processing and helps to achieve greater production.
Hot rolling process
Hot rolling is a metal processing process carried out at a temperature exceeding the recrystallization temperature of the material. During the material processing, after the particles are deformed during processing, they can recrystallize, maintain a uniform crystal structure, and prevent the metal from becoming too hard.
The new material is usually a cast semi-finished product such as ingots, billets, billets, and round billets.
Cold Rolling Process
Through the cold rolling process, the steel is processed at room temperature, increasing the hardness of the product by about 20%. This process also brings better aesthetics to the surface and maintains the accuracy of the original dimensions.
Cold rolling is usually applied to small products such as plates, strips, bars and tubes, which are much smaller than hot rolled products.
Is steel for construction usually hot rolled or cold rolled?
Steel for construction is usually a raw material selected from hot rolled steel, produced through a process of high temperature (hot rolled steel). By going through the hot rolling step, the steel becomes stronger and more flexible, ready for various uses.
However, in specific cases, cold rolled steel (cold rolled steel) also has some applications in construction projects, especially when high mechanical strength and dimensional accuracy optimization are required, such as when making windows, doors, etc…
In conclusion, although hot rolled steel still occupies a wide advantage in most current construction projects, the role of cold rolled steel in specific cases cannot be denied.
What is the difference between hot rolled steel and cold rolled steel?
As mentioned earlier, the main difference between hot rolled steel and cold rolled steel lies in the processing process. For hot rolled steel, it is rolled at high temperature to increase the crystallinity, while cold rolled steel is rolled at low temperature (below the crystallization temperature). There are also some significant differences between the two materials, such as:
Surface quality: Hot rolled steel usually has a rough surface and edges, so it needs to be decarburized or other treatment methods to be well used in other design applications. However, cold rolled steel is characterized by a smooth surface and high aesthetics, so it is used in most production activities.
Material hardness: When cold rolled, the steel acquires a higher strength and hardness than the finished product after hot rolling.
Therefore, buyers should never confuse the two types of steel without knowing the technical specifications. It will be very difficult to classify the finished products or understand their physical properties just by judging by the steel number.
Comparison table of cold rolled steel and hot rolled steel
Hot Rolled Steel | Cold Rolled Steel | |
Normal Thickness | 0.9mm and above | 0.15mm-2mm |
Surface | Black, typical dark color | Smooth, high gloss |
Edge Treatment | The edges on both sides are rounded and convex, which may rust over time. | Usually straight and sharp edges |
Storage | Can be stored outdoors for long periods of time without packaging | Usually packed and stored indoors. The surface is prone to rust and cannot be used |
Price | More expensive due to more processing required | The cost will be much cheaper because there is less processing |
Tolerance | The tolerance is smaller because it is rolled at low temperature, which makes it easier to control and less prone to deformation. | The tolerance is large because after hot rolling and cooling, it may deform on its own and is difficult to control |
Hot-rolled steel and cold-rolled steel prices
Both hot-rolled steel and cold-rolled steel have their own characteristics. However, according to different usage requirements, users can choose the most suitable product to meet production efficiency and cost requirements.
Compared with hot-rolled steel, cold-rolled steel has higher durability and toughness, and the durability is 20% higher than that of hot-rolled steel. The surface is difficult to be deformed by the external environment. It has a smaller error, beautiful appearance, easy to bend, and rarely breaks during processing. For these reasons, the price of this product will be much higher than that of hot-rolled steel.
The price of cold-rolled steel usually fluctuates between US$700-800/ton, depending on the type of steel and the manufacturer. At the same time, the price will fluctuate differently with different purchase times.
Why choose cold-rolled steel instead of hot-rolled steel?
Higher quality: Cold-rolled steel has higher strength and durability, and is stronger and more durable than hot-rolled steel.
Higher precision: Due to rolling at low temperatures, cold-rolled steel has higher precision.
Abrasion resistance: Due to better surface structure, cold-rolled steel is more difficult to wear than hot-rolled steel.
Extended service life: Cold-rolled steel has a longer service life and is more durable than hot-rolled steel, so it can minimize costs when used for a long time.
Where to buy genuine hot-rolled steel and cold-rolled steel?
At present, the domestic building materials market is very common. Therefore, most customers often don’t know which truly trustworthy source they should choose. In order to avoid unnecessary risks for users, you can contact JWB immediately.
We are a brand with a high reputation in the market, able to provide and distribute various types of steel products. Provide customers with the most reasonable quality, style and price.
With many years of experience in steel supply, JWB is always ready to provide customers with truly reliable and quality-assured products to meet the needs and universal needs of everyone.
Conclusion
Through the knowledge we summarize and share here, we hope to help everyone better understand the characteristics and differences between hot-rolled steel and cold-rolled steel. So as to help everyone make a better choice to meet their engineering needs.
If you need to consult the purchase and use of hot-rolled steel and cold-rolled steel, please feel free to contact JWB, we will provide you with comprehensive and professional support.
