China Hot Rolled and Cold Rolled Steel Coil Suppliers | Quality Steel Products from Factory
Specifications
| Parameter | Range / Options |
|---|---|
| Thickness | Hot Rolled: 1.2 mm – 25.4 mm Cold Rolled: 0.15 mm – 4.0 mm Galvanized: 0.2 mm – 3.2 mm |
| Width | 600 mm – 1,880 mm (standard ranges) |
| Coil Weight | 3 – 25 metric tons (typical) |
| Inner Diameter | 508 mm / 610 mm (standard) |
| Surface | Mill finish, pickled & oiled, galvanized, coated |
Types of Steel Coil
| Type | Manufacturing Process | Characteristics | Typical Thickness |
|---|---|---|---|
|
HRC Hot Rolled Coil |
Rolled above recrystallization temperature (1,000°C+) | Rough, bluish-gray surface; scaled finish; lower cost; good formability | 1.2 – 25.4 mm |
|
CRC Cold Rolled Coil |
Hot rolled coil further processed at room temperature | Smooth, shiny surface; tighter tolerances; increased strength; improved appearance | 0.15 – 4.0 mm |
|
GI Galvanized Steel Coil |
Zinc coating applied via hot-dip process | Corrosion-resistant; spangled or spangle-free finish; extended service life | 0.2 – 3.2 mm |
|
Galvalume Aluzinc Coil |
Aluminum-zinc alloy coating (55% Al, 43.5% Zn) | Superior corrosion resistance; better heat reflection; cut-edge protection | 0.2 – 2.5 mm |
|
PPGI Prepainted / Color Coated |
Galvanized substrate with paint application | Decorative colors; enhanced durability; coil coating process | 0.2 – 1.5 mm |
|
P&O Pickled & Oiled Coil |
Hot rolled with surface scale removed via acid bath | Clean surface; oiled for temporary rust protection; ready for further processing | 1.5 – 6.0 mm |
Manufacturing Process
Steel coil production begins with high-quality raw materials—iron ore, coal, and limestone—which are melted in blast furnaces to produce molten steel. Continuous casting forms the liquid steel into slabs, which are then prepared for rolling.
Steel slabs are heated above recrystallization temperature (approximately 1,000°C) and passed through large rollers that reduce thickness and stretch the material into long sheets. This process yields hot rolled coils with characteristic scaled surfaces.
Hot rolled coils may undergo pickling in hydrochloric acid tanks to remove surface oxides (scale) formed during hot rolling. This operation ensures surface quality for subsequent cold rolling or direct use. The process includes trimming edges and applying oil for temporary protection.
Pickled hot rolled coils are further processed at room temperature through tandem rolling mills. The combined action of loads and pulls reduces thickness while improving surface finish, flatness, and mechanical properties.
Cold rolled coils may receive heat treatment to relieve internal stresses and restore ductility lost during cold working.
For corrosion-resistant products, coils pass through continuous hot-dip galvanizing lines using the Sendzimir process. The strip immerses in molten zinc with small aluminum additions to improve adhesion and flexibility.
Coil coating lines apply paint via rollers, followed by heat treatment to polymerize coatings. The process includes degreasing, chemical pre-treatment, primer application, top coat finishing, and quality control testing.
Frequently Asked Questions
Hot rolled coil (HRC) is produced by rolling steel above its recrystallization temperature (~1,000°C), resulting in a rough, scaled surface and thicker gauges (1.2–25.4 mm). Cold rolled coil (CRC) is made by further processing hot rolled coil at room temperature, producing a smoother surface, tighter dimensional tolerances, and improved mechanical strength, typically in thinner gauges (0.15–4.0 mm).
The standard inner diameter for steel coils is 508 mm or 610 mm, which corresponds to common coil reel sizes used in processing lines worldwide. Coil weight typically ranges from 3 to 25 metric tons, depending on the thickness, width, and application requirements of the customer.
Galvalume coil uses an aluminum-zinc alloy coating (55% aluminum, 43.5% zinc) rather than pure zinc. This provides superior corrosion resistance compared to standard galvanized (GI) coil, better heat reflection properties, and cut-edge protection. It is widely used in roofing, cladding, and applications where long-term durability in harsh environments is required.
Pickling and oiling involves immersing hot rolled coil in hydrochloric acid tanks to dissolve and remove surface scale (iron oxides) formed during hot rolling. After pickling, the coil is trimmed and coated with a thin layer of oil for temporary rust protection. P&O coils are typically used when a clean, scale-free surface is needed for further processing such as cold rolling, stamping, or forming.
PPGI stands for Pre-Painted Galvanized Iron (or color coated coil). It is produced by applying paint coatings onto a galvanized steel substrate through a continuous coil coating process, including degreasing, chemical pre-treatment, primer, and top coat layers. PPGI is widely used in construction (roofing, wall panels, ceilings), home appliances, garage doors, and automotive interior components due to its decorative appearance and enhanced durability.
Cold rolling work-hardens the steel, increasing its strength but reducing ductility and making it more brittle. Annealing is a heat treatment process applied after cold rolling to relieve internal stresses within the steel's crystalline structure and restore ductility. This makes the material easier to form, stamp, or draw in subsequent manufacturing operations without cracking or failure.