Overview
Cold rolling process steel plate is produced by passing hot-rolled steel through rollers at room temperature, reducing thickness by 20–50%. This method refines grain structure, achieving tighter tolerances (typically ±0.05 mm) and smoother surfaces (Ra 0.4–1.6 μm) than hot rolling. The process increases yield strength by 30–80% through work hardening, making it ideal for applications requiring precision and durability. Common base materials include SPCC (low-carbon steel), 304 stainless steel, and high-strength alloys like DP600. Cold-rolled plates are available in thicknesses from 0.3 mm to 3 mm, with widths up to 2,000 mm. The absence of scale formation during processing eliminates the need for pickling, reducing post-production steps.
Structure and Working Principle
Cold rolling mills employ a series of tandem rolling stands, each applying incremental reduction at pressures up to 3,000 tons. The process begins with descaling hot-rolled coils via acid washing or mechanical abrasion. Subsequent rolling passes compress the metal while coolant systems maintain temperatures below 150°C to prevent recrystallization. Key equipment includes tension reels to prevent buckling and shape control systems like CVC (Continuously Variable Crown) rolls. The final product exhibits anisotropic properties, with longitudinal tensile strength 10–15% higher than transverse. Annealing may follow rolling to restore ductility (e.g., batch annealing at 680°C for 12 hours).
Key Features
Surface quality is a hallmark of cold-rolled plates, with Class A finishes achieving reflectivity over 80%. Dimensional consistency is exceptional, with thickness variation under 1% across coils. The process enables ultra-thin gauges down to 0.15 mm for electronics applications. Mechanical properties are tunable via roll pressure adjustments. A typical DC01 grade offers 270–410 MPa tensile strength with 28% elongation, while high-strength HSLA grades reach 550 MPa. The absence of oxide scale allows direct coating application, reducing pretreatment costs by approximately 15% compared to hot-rolled equivalents.
Application Areas
Automotive manufacturers consume approximately 40% of global cold-rolled output for body panels, chassis parts, and reinforcement components. The material's formability supports complex stamping operations with draw depths up to 1.5 times material thickness. Construction applications include lightweight structural sections and decorative cladding. In appliances, cold-rolled steel is preferred for refrigerator cabinets (0.5–0.8 mm thickness) and washing machine drums due to vibration resistance. Emerging uses include battery enclosures for EVs, where its EMI shielding properties are advantageous.
Maintenance and Precautions
Storage should prioritize horizontal stacking with wooden separators every meter to prevent deformation. Relative humidity must stay below 60% to avoid white rust formation on uncoated surfaces. Periodic oiling (e.g., ISO VG 32 hydraulic oil) is recommended for long-term storage. During fabrication, tool wear is accelerated by the material's hardness—carbide tooling with 12–15° rake angles is advised for machining. Welding requires preheating to 150–200°C for thicknesses above 2 mm to prevent cold cracking. Post-weld stress relief at 580–620°C may be necessary for critical applications.
B2B Procurement Guide
Specify requirements using international standards: ASTM A1008 for general purpose, EN 10130 for deep drawing grades, or JIS G3141 for Japanese market compliance. Key parameters to define include flatness tolerance (typically ≤3 I-units), hardness (HRB 40–90 range), and spangle size for galvanized products. Lead times average 6–8 weeks for custom orders. MOQs are usually 20–30 metric tons, though spot purchases may be available at 10–15% premium. Third-party inspection should verify magnetic permeability for electrical applications (max 1.05 μr for shielding uses). Consider toll processing services for slitting to widths under 300 mm.
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