Hot Rolled and Cold Rolled Steel Coil
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 |
| Hot Rolled Coil (HRC) | Rolled above recrystallization temperature (1,000°C+) | Rough, bluish-gray surface; scaled finish; lower cost; good formability | 1.2 – 25.4 mm |
| Cold Rolled Coil (CRC) | Hot rolled coil further processed at room temperature | Smooth, shiny surface; tighter tolerances; increased strength; improved appearance | 0.15 – 4.0 mm |
| Galvanized Steel Coil (GI) | 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 |
| Prepainted / Color Coated Coil (PPGI) | Galvanized substrate with paint application | Decorative colors; enhanced durability; coil coating process | 0.2 – 1.5 mm |
| Pickled & Oiled Coil (P&O) | 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
Raw Material Preparation: 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.
Hot 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.
Pickling: 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.
Cold Rolling: 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.
Annealing: Cold rolled coils may receive heat treatment to relieve internal stresses and restore ductility lost during cold working.
Galvanizing: 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.
Coating / Painting: 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.