Cold Rolled Steel Sheet & Coil

Cold-rolled coils are steel products delivered in coils, manufactured from hot-rolled coils. After pickling to remove iron oxide scale, they are rolled at room temperature, followed by degreasing, annealing, and leveling processes. They are an indispensable basic material in modern high-end manufacturing.

The main product forms of cold-rolled coils include:

Cold-rolled coils are an important substrate for producing coated products such as galvanized sheets, tinplate, and color-coated sheets. The production process of cold-rolled coils is complex and highly automated, representing the highest level of steel rolling technology.

The manufacturing process of cold rolled coils usually includes the following steps:
1. Hot Rolling: First, the original steel is subjected to a hot rolling process at high temperatures to heat it to a higher temperature, and then it is pressed into the required thickness and width by a roll mill to form hot rolled steel coils.
2. Pickling: Hot rolled coils are pickled to remove surface oxidized skin and contaminants to ensure better surface quality after cold rolling.
3. Cold Rolling: Hot rolled steel coils are re-rolled at room temperature in a cold rolling mill. The thickness of the steel in this process will become more uniform, while the surface will become smoother.
4. Annealing: Cold rolled coils may need to be annealed to remove internal stresses and improve the ductility and workability of the steel.

Core process
Hot rolled coil (raw material) → Pickling → Cold rolling → Degreasing → Annealing → Smoothing → Finishing → Finished Product Warehousing

Cold-rolled coils suffer from work hardening, leading to deteriorated stamping performance. Annealing is essential to restore their mechanical properties.
There are two main annealing processes:
Banner-type annealing:Step-by-step annealing, with heating temperatures typically controlled between 680 and 720°C;
Continuous annealing:High production efficiency, suitable for mass production.
After annealing: The strip surface is bright, and plasticity is restored, making it suitable for stamping.

Chemical Composition (Typical Values)

Core Performance Characteristics:
1. Excellent Surface Quality: Cold rolling does not involve heating, eliminating defects common in hot rolling such as pitting and iron oxide scale. The surface quality is excellent, with high smoothness. Strips with different surface roughnesses (glossy or roughened surfaces, etc.) can be produced according to customer requirements.
2. High Dimensional Accuracy: Cold-rolled products have high dimensional accuracy, with thickness deviations controllable within 0.01–0.03 mm. High-end precision products can achieve thickness accuracy below ±5 μm.
3. Excellent Mechanical Properties: After annealing, cold-rolled sheets exhibit superior mechanical and processing properties compared to hot-rolled thin steel sheets. They primarily utilize low-carbon steel grades and require good cold bending and welding performance, as well as certain stamping properties.
4. Good Stamping Performance: Cold-rolled sheets possess high stamping performance, low yield point, and no aging properties, making them particularly suitable for deep drawing. Cold rolling allows for the production of thinner, more precise, and flatter products.
5. Easy to Coat and Plate: Cold-rolled sheets have a clean and bright surface, facilitating painting, electroplating, and other surface treatments. They are ideal substrates for coated products such as galvanized sheets and color-coated sheets.

Cold-rolled coils, characterized by their smooth surface, high dimensional accuracy, and excellent stamping performance, are widely used in automotive manufacturing, home appliances, electronics, machinery, and construction industries. Currently, cold-rolled coils are rapidly developing in the direction of high strength, ultra-thinness, high precision and intelligent manufacturing.

Key differences between cold-rolled coils and hot-rolled coils:

To summarize, cold rolled steel coil, as a metal material treated by a special process, has many unique characteristics. Its high strength, good toughness and excellent surface quality make it widely used in industries such as automotive, construction and home appliances. With the advancement of technology and growing demand, the development prospect of cold rolled steel coils will be even broader. Whether in the lightweight design of new energy vehicles, the structural stability of high-rise buildings, or the environmental performance of home appliances, cold rolled steel coils will play an important role in contributing to the development of different industries.

Cold rolled coil is a metal product that produced from hot rolled steel coils through a cold rolling processing. Different countries may have different standards to regulate the production and quality requirements of cold rolled steel sheet & coil. The following are some representative national standards for cold rolled steel sheet & coil:

Chinese standard:
The structural standard of cold-rolled steel sheets and strips in my country is GB/T 708-2019.
This standard specifies the terms and definitions, classification and code, size,dimensional deviation, shape requirements, measurement of size and shape, weight and numerical rounding off for cold-rolled steel sheets and strips.

British Standard:
BS EN 10130:2006 Technical delivery conditions for cold-rolled mild steel sheet for cold forming

American Standard:
ASTM A1008/A1008M-21. This standard specifies the standard specifications for steel plates, cold rolled, carbon, and structural, including cold rolled steel plates for various purposes.

Japanese standard:
JIS G 3141:2017. This standard specifies the technical delivery conditions for cold-rolled carbon steel sheets and strips.

The grade system for cold-rolled coils covers four major series: Chinese standard, Japanese, European, and German.

Cold rolled products have high dimensional accuracy, and the properties and organization of the products can meet some special requirements for use, such as electromagnetic properties and deep drawing properties.

Thicknesses between 0.18 and 3.5 mm;
Widths between 600 and 2 000 mm;
Plate lengths between 1 200 and 6 000 mm.

The deviations of thickness, width and length of cold rolled coils are usually determined according to national standards or manufacturer's regulations, and the permissible deviations will vary according to the specific circumstances, generally based on thickness and width.

For nominal thicknesses less than 1mm, increments of 0.05mm are used; for thicknesses not less than 1mm, increments of 0.1mm are used. Nominal widths are increments of 10mm; nominal lengths are increments of 50mm. Sizes other than the standard can be supplied upon negotiation between the supplier and the buyer.

Actual Supply Range of Some Steel Mills:

Baosteel: Cut-edge steel plate thickness 0.30～3.50mm, width 700～1830mm
Hebei Iron & Steel Tangshan Iron & Steel: thickness 0.18～3.00mm, width 800～1600mm
Baosteel Precision Strip Steel Mill: thickness 0.17mm～0.80mm