Cold Rolled vs. Hot Rolled Steel

​Cold Rolled vs. Hot Rolled Steel

You will find several factors and terms used in the metal and steel fabrication industry that some people have heard, but not exactly sure what they mean. One example of this is seen in the differences that are present between cold rolled and hot rolled steel.

The fact is, there are a few clear differences present between these two metals. The differences present relate to how the metals are processed in the mill, not the product grade or specification – which is a common misconception.

For example, hot rolled steel requires a process that involves rolling this product at higher temperatures. With cold rolled steel, it is processed in a cold reduction mill. During this processing, the steel is cooled after the annealing or tempers rolling process.
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While all this may sound a bit confusing for those who are not in the industry, learning more about each one can help you better understand what projects and applications each type of steel is appropriate for. Keep reading to learn more about each of these options.

Getting to Know Hot Rolled Steel
With hot rolling, a mill process is used. This process involves rolling the steel at higher temperatures. In most cases, the temperatures will exceed 1700 degrees Fahrenheit. This is higher than the recrystallization temperature of the steel.

After the steel has exceeded this recrystallization temperature, people using this steel have found it is ease to shape and to form. Also, the steel can be transformed into larger sizes. Usually, you will find that hot rolled steel is more affordable than cold rolled steel. This is because it is typically manufactured with no delays between the steps in the process. This also means that there is no need to reheat the steel, which is a step that is required for cold rolled steel products.

As the hot rolled steel starts to cool, it will also begin to shrink. This will provide minimal control regarding the shape and the size of the final product, which is not the case with cold rolled steel products.

Common Uses for Hot Rolled Steel
Some of the most common uses for hot rolled steel include in products such as hot rolled steel bars. These are commonly used in the construction and welding industries to create several products, including I-beams and railroad tracks (as an example). Also, with hot rolled steel, it can be used in situations where more precise tolerances and shapes are needed.

The Top Benefits of Hot Rolled Steel
Since less processing is required for hot rolled steel, it makes it much more affordable. Also, because the products are normalized, which means it is free from any internal stresses which may occur from work-hardening or quenching, it is stronger and more durable.

Also, this option is the right one if dimensional tolerances are not as essential as how strong the material is. If strength and surface finishes are a concern, scaling is able to be removed through several processes, including sand blasting, and grinding.

Getting to Know Cold Rolled Steel
Compared to hot rolled steel, cold rolled steel has a more involved processing process. For example, the steel will be processed during another step, which involves placement in a cold reduction mill. This is when the material is fully cooled, which is done in the temperature of the room where the work is done. After this, an annealing or a temper rolling process is conducted. The process helps to create steel that has higher dimensional tolerances, along with many more surface finishes to choose from.

The phrase “cold rolled” is sometimes used for all products – which is a mistake. The product name is actually a reference to rolling the coil and flat rolled sheet products.

When someone is referring to a bar product, the term that is used is “cold finishing.” This will usually include cold drawing or polishing, grinding, and turning. With this process, there are higher yield points and there are four main benefits to this. These benefits include:

• Cold Drawing: This helps to increase the tensile strengths and yields while helping to eliminate any need for more expensive thermal treatments.
• Turning: This process is used to help eliminate all types of surface imperfections.
• Grinding: This process will be used to help marrow the original size and tolerance range.
• Polishing: Used to help improve the surface finish.

All of the cold rolled products will provide the end user with a higher quality surface finish. They are also superior in other ways, including straightness, concentricity, and tolerance when compared to the hot rolled products.

In most cases, cold finished bars will be harder to actually work with than the hot rolled options because of the higher content of carbon. However, this is not true about cold rolled sheet and hot rolled sheet. When comparing these products, cold rolled products have much lower carbon content and is usually annealed, which makes it much softer than the hot rolled sheets.

Used for Cold Rolled Steel
There are several uses for cold rolled steel. However, it is commonly requested and used for any project or application where there are concerns related to straightness, concentricity, surface condition, and tolerances.

Benefits of Cold Rolled Steel
Cold rolled steel is in demand for the higher quality surface characteristics compared to hot rolled steel. In fact, this makes it clear that products designed with cold rolled steel will be go-to option for applications that require technically precise solutions or in situations where aesthetics is a more important factor. However, because of the extra processing that is required for the cold rolled and finished products, cold rolled steel is more expensive than hot rolled steel.

Getting the High Quality Products You Need
When it comes to hot versus cold rolled steel, there are several factors to consider. However, if you want to ensure that you get the highest quality products available, it is essential that you find a quality metal supplier. By doing this, you can feel confident that you will receive the results that you want and need. When it comes to hot vs. cold rolled steel, there are some definite differences. While this is true, you will find that each product has specific applications and benefits, which means you will likely require one over the other for your project.