The current steel market offers two primary types of steel – hot rolled and cold-rolled steel. The question is, which one is better, and which one should you use in your project if you aim for high strength? This time, you will learn what type of steel is ultimately stronger and what parameters determine the strength of steel. Now, let’s dive into the main difference between hot-rolled and cold-rolled steel.
Hot Rolling vs. Cold Rolling: What’s the Difference?
Hot rolling is the process of forming rolled metal sheets at high temperatures through rolling mills – typically above 1,700° F. Why work with preheated metal in the first place? It’s because the crystal structure of steel melts and softens. As a result, it’s much easier to deform, allowing steelworks to produce tons of hot rolled steel every day.
Cold rolling essentially involves the same process at room temperature. Cold-rolling always applies to metal sheets that have already undergone hot rolling. There is no way you can produce sheet metal using cold, thick ingots.
So cold rolling is a processing technique applied to hot-rolled steel to refine its texture, improve its dimensions, and enhance its mechanical properties.
Hot Rolled vs. Cold Rolled Steel: Which One Is Stronger?
If you compare the strength of hot-rolled and cold-rolling steel of the same grade, the latter will be 20% stronger on average.
It happens due to work hardening. When flattened through rollers, metal gets thinner – its grains become thinner, longer, and smoother. The rollers make metal crystals tighter.
They slide upon each other, rearrange, and tighten. The more you press the metal sheet, the more resistance against pressure it produces. At some point, the crystals create the most stable and resistant formation.
Steel Grade Matters a Lot More than a Rolling Method
Can a hot-rolled steel sheet be stronger than a cold-rolled one? It absolutely can if it’s made of more durable steel. For instance, A36 steel, one of the most used hot-rolled steel grades, demonstrates a yield strength of 250 MPa or 36,300 psi. It also comes in a cold-rolled version, exhibiting a yield strength of 300 MPa or 43,500 psi.
However, 1018 cold-rolled steel has a yield strength of 370 MPA or 53,700 psi. So it’s 123.5% stronger than cold-rolled A36, let alone its commonly used hot-rolled version.
On the other hand, S960MC structural hot rolled steel demonstrates a yield strength of 960 MPa or 139,236 psi, outperforming cold-rolled 1018 by 174%.
As you can see, the steel grade matters a lot more than a metal processing technique. Cheap cold-rolled sheets can show lower strength than high-end hot-rolled metal.
Meanwhile, high-end cold-rolled steel will be way superior to even the most durable hot-rolled metal grades. At this point, you should check which steel grade delivers the best properties for your metal project.
Which Type of Steel to Choose If You Need Strength?
It’s hard to tell which steel you need if you consider strength only. This checklist will help you define whether you need cold-rolled or hot-rolled steel:
- What surface finish do you require? If it doesn’t matter, opt for high-end hot-rolled steel grades.
- Do you prefer thick or thin steel sheets? If you need thin but strong steel sheets, you should opt for cold-rolled metal.
- Do you need precise dimensions for steel sheets that will require minimum processing? If yes, you should opt for cold-rolled steel.
- What is your budget? Steel suppliers comply with international standards but sell the rolled metal at different prices. If you need strong, sleek, and thin metal at an affordable price, you can order cold rolled steel sheet in Metinvestholding. This company delivers ASTM-certified cold-rolled steel internationally.
The Bottom Line
Cold-rolled metal is more durable than its hot-rolled version assuming they’re made of the same steel grade. Metal strengthens due to cold rolling as its crystals rearrange in a more stable formation. But initial steel composition matters more than forming techniques regarding absolute and yield strength of the metal.
Therefore, you should check various steel grades for chemical composition and properties to get metal suitable for your project. Which steel to choose depends on your demands and preferable steel properties, including surface finish, dimensional tolerances, and others. Eventually, you have to choose a steel supplier which prices and metal products will satisfy your needs.
Article Submitted By Community Writer