Introduction
Roll forming involves shaping steel into desired profiles through a series of rollers. The type of steel used—hot rolled or cold rolled—affects the properties of the final product. Here’s a detailed comparison of hot rolled steel and cold rolled steel in roll forming, along with their key differences and applications:
Hot Rolled Steel
Description:
- Manufacturing Process: Hot rolled steel is produced by rolling the steel at high temperatures (above its recrystallization temperature, typically over 1700°F or 926°C).
- Surface Finish: The high temperature causes the steel to develop a rough, scaled surface finish.
- Dimensions: Hot rolled steel tends to have more variation in dimensions due to the cooling process, which can cause slight distortions.
Properties:
- Strength: Generally lower strength compared to cold rolled steel.
- Ductility: Higher ductility, making it easier to work with during manufacturing.
- Tolerance: Less precise dimensional tolerances.
Applications:
- Construction: Beams, columns, and other structural components.
- Automotive: Frames and chassis.
- Agriculture: Equipment and machinery parts.
- General Manufacturing: Components where precise dimensions are not critical.
Cold Rolled Steel
Description:
- Manufacturing Process: Cold rolled steel is produced by further processing hot rolled steel through cold reduction mills at room temperature, followed by annealing and/or temper rolling.
- Surface Finish: Results in a smoother, more polished surface finish.
- Dimensions: More precise dimensions due to the cold reduction process.
Properties:
- Strength: Higher strength and hardness compared to hot rolled steel.
- Ductility: Lower ductility, making it less formable but more rigid.
- Tolerance: More precise dimensional tolerances.
Applications:
- Automotive: Exterior and interior panels, precision components.
- Home Appliances: Parts requiring a high-quality finish, like refrigerators and washing machines.
- Furniture: High-quality office furniture and storage solutions.
- Electrical: Components requiring precise dimensions and smooth surface finishes.
Comparison Table
| Feature | Hot Rolled Steel | Cold Rolled Steel |
| Manufacturing Process | Rolled at high temperatures | Rolled at room temperature |
| Surface Finish | Rough, scaled | Smooth, polished |
| Strength | Generally lower | Higher |
| Ductility | Higher | Lower |
| Tolerance | Less precise | More precise |
| Cost | Generally less expensive | Generally more expensive |
| Applications | Construction, automotive frames, machinery |