Available in various grades, specifications, shapes, and finishes, steel can be used to fabricate infrastructure, appliances, vehicles, and a wide range of other parts and products. Even when the grades and specifications of the materials are the same, the specific manufacturing process used can greatly affect the outcome of the final steel products. When choosing materials, understanding the distinctive qualities of the types of steel available is crucial for ensuring optimal results.
Below, we’ll explore the difference between hot rolled and cold rolled steel.
Hot Rolled vs. Cold Rolled Steel
When distinguishing between prefabricated steel products, it’s important to determine whether the steel is hot rolled or cold rolled, but what’s the difference between hot rolled and cold rolled sheets? These metals don’t differ in product specification or grade; rather, different processes are used at the mill to create the two materials. Hot rolled steel involves rolling steel at high temperatures, while cold rolled steel refers to processes done at or near room temperature.
Certain types of steel will work better with certain applications, so understanding the differences between the hot rolling and cold rolling processes can help save time and money, eliminating unnecessary processing steps and reducing the risk of overspending on raw materials.
What is Hot Rolled Steel?
Hot rolling involves roll pressing steel at temperatures over 1700 °F. Raising the steel’s recrystallization temperature allows the material to be easily shaped or formed into large pieces. Beginning with a heated billet or a sizable, rectangular length of metal, the material is flattened by a large roller. Keeping the metal at a high temperature, the material is run through several rollers to attain its desired measurements.
Unlike cold rolled steel, hot rolled steel does not require reheating, which means the material can be manufactured without any delays, in turn allowing for reduced costs. Since hot rolled steel cools slowly to room temperature, the material is virtually free from internal stresses and is easily stabilized. However, steel shrinks as it cools, which means there is less control over the final shape of hot rolled steel.
These factors make hot rolled steel ideal for:
- Railroad tracks
- Construction projects
- Beams
- Cross-sections
- Sheet metal
Benefits of Hot Rolled Steel
The main benefits of hot rolled steel are as follows:
- Usually requires less processing than cold rolled steel
- Allows for significant cost savings due to minimal processing requirements
- Normalized, or free from internal stresses that can come about during work-hardening or quenching processes
- Ideal for high production runs
- Can be used for a wide range of shapes
- Speedy process
What is Cold Rolled Steel?
To create cold rolled steel, the material is rolled again, at room temperature, after it has cooled to allow for more precise dimensions and improved surface qualities. Essentially, cold rolled steel is hot rolled steel with additional processing. Cold rolled steel is frequently used in projects or applications requiring enhanced aesthetics. Because the material is shaped at lower temperatures, cold rolled steels are generally harder and stronger than hot rolled steels,
Cold rolled steel is ideal for the manufacture of products such as:
- Machine parts
- Automotive components
- Strips
- Rods
- Sheets
Cold rolled metal is also well suited to any project requiring pristine surface condition and exact proportions.
Benefits of Cold Rolled Steel
Some of the key advantages of cold rolled steel include:
- High-quality finished surfaces
- Close tolerances
- Good resistance to tension breaking and deformation thanks to work-hardening processes
- Ability to create well-defined corners and edges in bars
- Optimal straightness and concentric uniformity in tubes
- Ideal for technically precise project requirements
- Usually harder and stronger than hot rolled steel
- Allows for enhanced aesthetics
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