Views: 0 Author: Monica Publish Time: 2025-09-05 Origin: Site
Steel coil, also known as coil steel, is formed into a coil through hot and cold pressing, are rolls of flat steel that manufacturers shape into different products used in many industries. Formed steel coils can be categorized as hot-rolled coil and cold rolled coil. Hot-rolled coil is the product of the steel slab before recrystallization, while cold rolled coil is a subsequent process. Coil weight typically ranges from 1 to 30 tons.
JN is a leading steel coil manufacturer and supplier in China, offering stainless steel and duplex alloy coils. Our custom coil processing capabilities include:
Length: 0-12m or as per your requirements.
Width: 0-2500mm or as per your requirements.
Thickness: 0.3-1200mm or as per your requirements.
Process: Hot/cold rolled.
Surface: No.1, No.2D, No.2B, BA, No.3, No.4, No.6, No.7.
Processing 1: Pickling
First, the steel coil goes through pickling to clean its surface. The coil unwinds and passes through tanks filled with acid. This acid washes away rust, scale, and dirt that formed when the steel was made. Hot water rinses off the acid afterwards. The steel becomes shiny and clean for the next steps. Special machines constantly check the acid strength and temperature to make sure it works perfectly. Without it, the steel wouldn't work well in later processes.
Processing 2: Rolling
Next comes rolling, where heavy machines squeeze the steel to make it thinner. The steel passes between big rotating cylinders called rolls. Cold rolling happens at room temperature and makes very precise, thin sheets. Hot rolling is done while the steel is still warm from making it. Both methods use powerful presses that can be as strong as 50 cars! The rolls can be changed to make different thicknesses, from thick panels to thin foil. Computer sensors measure the thickness every second to keep it exact.
Processing 3: Annealing
After rolling, the steel becomes too hard and needs annealing. The coil heats up in a special oven to about 1,300°F. It stays hot for hours, then cools down slowly. This treatment relaxes the steel's structure so it becomes flexible again. Different types of steel need different temperatures and times. Some ovens use gas flames, while others use electricity. The annealing step is like giving the steel a "reset" so we can shape it without breaking.
Processing 4: Tempering
Now we adjust the steel's strength through tempering. The steel heats up again, but not as hot as annealing. Temperatures range from 300°F to 700°F. This makes the steel stronger while keeping some flexibility. It's like baking cookies—too little leaves them soft, and too much makes them hard. Workers carefully control the oven temperature and how long the steel stays inside. Some steel coil gets tempered several times to get just the right properties.
Processing 5: Coating
Finally, the steel coil gets coatings to protect it. Common coatings include galvanizing, paint, or plastic. For galvanizing, the steel dips in molten zinc at 850°F. The zinc sticks to the steel coil and blocks rust. Painted steel gets sprayed with liquid color that bakes dry. Plastic coatings use special glues and heat to bond plastic layers. Each coating method has machines that spread the material evenly and check for defects. The result is steel that lasts years outdoors without rusting.
Processing 6: Slitting
The last step is slitting; it means cutting the wide coil into narrower strips. Sharp circular knives slice the steel as it moves fast down the line. One big coil can make many small coils of different widths. The edges get smoothed so they won't cut workers' hands. Computers guide the knives to cut accurate widths with hair-thin precision. Finished steel coils get wrapped tight with protective covers for shipping to factories that will make them into cars, appliances, or buildings.
Steel coils are very flexible because they can be cut, bent, and reshaped into various forms needed for construction, cars, appliances, and more. Below are some of the most common uses of steel coils in everyday life.
Construction and Building Structures
Steel coils are widely used in construction because they are strong and can withstand heavy weight. After being unrolled, they are cut into sheets or shaped into beams, panels, and roofing materials. Large buildings, bridges, and warehouses often use steel coils because they last longer than wood and resist damage from bad weather, fire, and rust. Metal studs made from steel coils help create the skeleton of houses and offices, making them stable and safe.
Automobiles and Vehicle Manufacturing
Car makers rely on steel coils to produce strong yet lightweight parts for vehicles. The steel is pressed into car doors, hoods, frames, and body panels to protect passengers during accidents. Because steel bends easily without breaking, it helps absorb crash impacts better than some other metals. Trucks, buses, and trains also use steel coils to build durable frames and wheels that can carry heavy loads over long distances without wearing out quickly.
Household Appliances and Electronics
Many home appliances are made from steel coils because the metal is sturdy, heat-resistant, and easy to clean. Refrigerators, washing machines, ovens, and dishwashers all have outer shells and internal parts made from rolled steel. Electronic devices like computers and air conditioners also use steel coils for protective casings that block electrical interference and keep the machines running safely. The smooth coating on steel prevents rust and keeps appliances looking new for years.
Pipes and Tubes for Water, Oil, and Gas
Steel coils can be bent and welded into strong pipes that transport water, oil, and gas underground or inside buildings. These pipes must handle high pressure without leaking, which is why steel is a better choice than plastic in many cases. Oil rigs and chemical factories use specially coated steel pipes to resist corrosion from salty water or harsh chemicals. Steel tubes also support fences, railings, and scaffolding in construction projects because they are lightweight but tough.
Packaging and Shipping Materials
Companies use thin steel coils to make metal cans for food, drinks, and aerosol sprays. These cans protect products from air, moisture, and bacteria, keeping them fresh for months. Shipping companies use steel bands cut from coils to secure heavy boxes and cargo on trucks and ships, preventing damage during transportation. Even small steel coils are used to make bottle caps and lids that seal tightly and stay in place until opened.
How much does a steel coil weigh? The weight of a steel coil depends on its size, thickness, and grade of steel. However, most industrial steel coils weigh between 1 ton and 30 tons. Besides, smaller coils for light manufacturing might weigh as little as 0.25 tons, while the largest coils used in heavy industry can exceed 40 tons.
To find a steel coil weight, you need three measurements:
Width (W): How wide the steel is in inches or meters.
Thickness (T): How thick the steel is in inches or millimeters.
Length (L): How long the unrolled steel would be in feet or meters.
You can also use the outer diameter (OD) and inner diameter (ID) of the coil if the length is unknown.
If you know the length of the coil steel, use this formula:
Weight (lbs)=Width (inches)×Thickness (inches)×Length (feet)×Density of Steel
(Density of stainless steel = 7.85 g/cm³ ≈ 0.2836 lbs/in³)
Example:
Width (W) = 48 inches
Thickness (T) = 0.1 inches
Length (L) = 500 feet
Calculation:
48×0.1×500×0.2836=6,806.4lbs/3.4tons
If you don't know the length, measure the outer diameter (OD) and inner diameter (ID) (in inches). Then use this formula:
Example:
OD = 60 inches
ID = 20 inches
Width (W) = 48 inches
Calculation:
Hot rolled coils are made by heating steel slabs and rolling them at high temperatures. These are the cheapest steel coils and are used in construction, pipes, and car frames. Common grades include A36, A572, and 1018. Standard sizes are 0.075–0.25 inches thick and 36–72 inches wide. In July 2024, prices were:
Grade | Price (per ton) | Common Uses |
A36 | 650–650 – 650–750 | Construction, machinery |
A572 Gr.50 | 750–750 – 750–850 | Bridges, buildings |
1018 | 700–700 – 700–800 | Bolts, pipes |
Prices change based on demand, energy costs, and trade rules.
Cold rolled coils are made by further processing hot-rolled steel to make it smoother and stronger. These are more expensive and used in cars, appliances, and furniture. Common grades are 1008/1010 and 300 series stainless (like 304 ). Standard sizes are 0.015–0.15 inches thick and 36–60 inches wide. Prices in July 2024 were:
Grade | Price (per ton) | Common Uses |
1008/1010 | 900–900 – 900–1,100 | Cars, shelves |
304 SS | 2,800–2,800 – 2,800–3,300 | Appliances, medical tools |
Cold rolled prices depend on extra treatments and are usually higher than hot-rolled steel.
What is hot rolled coil steel?
Hot rolled coil steel is made by heating steel slabs above 927°C and rolling them into thin, flat sheets. This process makes the steel easier to shape but leaves a rough surface. Hot rolled steel is cheaper than cold rolled and is used in construction, pipelines, and heavy machinery.
Why are steel coils so hot?
Steel coils stay hot because they are rolled right after heating in a furnace. Keeping them warm makes them softer and easier to bend into shape. Cooling slowly also prevents warping and cracking, ensuring a strong final product.
Why are steel coils transported upright?
Steel coils are shipped standing up to save space and prevent damage. Laying them flat could deform the edges or cause uncoiling during transit. Upright transport is safer and more stable for trucks, trains, and ships.
