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Steel is an indispensable material in construction, engineering, and manufacturing owing to its versatility. Out of the many forms that steel can take, hot-rolled steel and cold-rolled steel are the most popular. These varieties of steel are known to have specific attributes set by the difference between hot and cold rolled steel. This distinction becomes even more crucial when it is considered about how steel is utilised in Thermo Mechanically Treated (TMT) bars, which serve as the core building blocks in modern infrastructure projects.
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In this blog, we will analyse the differences in hot rolled vs cold rolled steel, why hot rolling is the favoured method in the manufacturing of TMT bars, and where cold rolling fits into the steel worldview.
What is Hot Rolled Steel?
Hot rolled steel is the type of steel that has gone through the process of rolling at a high temperature, specifically over 1,700°F (926°C). At this temperature range, steel becomes soft, making the forming process easier. The process includes steel slabs or billets being passed through the rolling mills while still hot to thick and shaped.
Properties of Hot Rolled Steel:
- Surface textures are coarse because of scale build-up.
- Inaccuracies in dimensions because of cooling shrinkage.
- Simplicity in forming and shaping.
- Amicable to hot rolled steel price.
Structural beams, pipes, railway tracks, and TMT bars are examples of goods that use hot rolled steel on an industrial scale.
What Is Cold Rolled Steel?
Hot rolled steel, which has received additional treatment, is referred to as cold rolled steel. After cooling the steel, it is reduced in thickness and polished using rollers at room temperature.
Properties of Cold Rolled Steel:
- Glossy surface.
- More accurate measurement.
- Enhanced strength because of strain hardening.
- Less affordable compared to hot-rolled steel.
Because of its superior looks alongside tighter tolerances, cold rolled steel is popular in applications demanding high precision and quality surfaces, like in automotive panels, appliances, and furniture.
Key Differences Between Hot And Cold Rolled Steel
Let us analyse the difference between hot rolled steel and cold rolled steel in a table:
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The difference between hot and cold rolled steel is present in the rolling stage and the resulting properties.
Reasons for Choosing Hot Rolled Steel in the Production of TMT Bars
TMT bars manufacturing processes use hot-rolled steel as the raw material. Let’s see the reasons to explain this.
1. Scalability and Efficiency
TMT bars require Hot Rolling because of their efficiency during the manufacturing stage. The construction industry requires steel TMT bars in bulk, hot rolling will allow efficient production using less time.
2. Improved Ductility and Formability
Hot rolled steel ductility is formability. For the steps within the TMT process of quenching and self-tempering, this feature becomes very useful. Also, during the TMT process, the core part of the steel, which is ductile, ensures flexibility.
3. Most Economical
In comparison with cold rolled steel, hot rolled steel doesn’t need additional processing, which makes it hot rolled steel more economical. A certain percentage of savings can truly make a difference in large-scale projects.
4. Most Suitable for Thermo-Mechanical Treatment
After rolling in the TMT manufacturing process, the bars are rapidly quenched, which leads to surface hardening. Semi-finished rolled objects bearing a high temperature are more effective when hot-rolled steel is applied, especially during the above-described treatment.
Once again, hot-rolled steel remains untouchable in meeting the requirements of the TMT process and is preferred in the production of reinforcement bars.
Is Cold Rolled Steel Ever Used In TMT Bars?
In general, no. Cold-rolled steel does not feature in the primary processing of TMT bars. It is far too rigid and strong with brittleness and reduced ductility, unsuitable for most applications requiring flexibility and resilience.
In addition, cold-rolled steel is more expensive without providing any additional benefits to rebar production. Its application is therefore restricted to precision parts instead of structural reinforcements.
Summary of Hot Rolled versus Cold Rolled Steel In the Context Of TMT
Here's an example comparison that focuses on TMT bar manufacturing:
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This shows the true differences between hot and cold rolled steel in terms of TMT bar usage.
Other Uses of Hot and Cold Rolled Steel
As TMT bars are hot-rolled steel, they benefit from its properties, but each type of steel has a diverse use:
Applications of Hot Rolled Steel:
- Channels and beams in constructions
- Pipes and tubes
- TMT bars and steel reinforcement
- Railway tracks
Applications of Cold Rolled Steel:
- Auto parts and accessories
- Dining and living room furniture
- Home and kitchen appliances
- Lockers and cabinets
Both types of steel have different applications across diverse industries all over the world, depending on budget and performance requirements.
Also Read: Unlocking the Strength: The Role of CRCA Sheets in TMT Manufacturing
Conclusion
Knowing the hot rolled vs cold rolled steel argument when talking about steel is crucial to pick the material one intends to use. As discussed above, with TMT bars, hot-rolled steel takes the crown in this case. This is because it's supple, economical, and works well with thermo-mechanical treatment processes, which makes it easy to produce reinforcement bars required in modern construction.
Better understanding the hot rolled steel and cold rolled steel differences can be beneficial to the entire supply chain, from manufacturers to contractors, engineers, and builders. This information is critical whether one is engaged in the production of steel or procuring it for a construction project, as it greatly affects the resultant structure’s quality and longevity.
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