In steel rolling production, rolls are key components that directly affect rolling efficiency, product quality, and production costs. The performance requirements for rolls vary among different types of rolling mills. Therefore, when selecting a model, factors such as strength, hardness, wear resistance, impact resistance, surface finish, and cutting performance need to be comprehensively considered
Resistance to thermal cracking (a key requirement for coarse rolls)
During the rolling process, coarse rolls are subjected to tremendous rolling forces and high temperatures. Therefore, resistance to thermal cracking and high strength are their main performance indicators.
Example:
Wide and thick plate rolling mills use massive support rolls. Some weigh over 200 tons. In contrast, small 20-roll mills use tiny work rolls. These may weigh just 100 grams.
Material selection depends on load needs. Common options include:
- Cast iron.
- Cast steel.
- Forged steel.
Choose based on the rolling mill’s strength requirements.
Hardness and wear resistance (Core indicators of precision rolls)
Finishing rolls must ensure final product surface quality. Therefore, high hardness and wear resistance are critical.
Roll wear depends on multiple factors:
Mechanical stress.
Thermal stress.
Cooling media effects.
Lubricant chemistry.
No single standard exists to measure wear resistance. Instead, radial hardness curves are used. This works because hardness and wear resistance often correlate.
Impact resistance (The key to large reduction rolling)
Large-reduction rolling demands tough rolls. They need:
Strong bite ability.
High impact resistance.
Without these, rolls may:
Peel.
Crack.
Hot rolling faces extra challenges:
Extreme temperature swings.
Heavy mechanical shock.
Surface finish (Strict requirements for thin-gauge rolling)
When rolling thin plates or high-precision steel strips, the rigidity, uniformity of the structure, processing accuracy and surface finish of the rolls directly affect the surface quality of the products. Any minor defect on the roller surface may cause scratches or unevenness on the surface of the sheet.
Machining performance (Special Requirements for section steel rolls)
For complex section steels (such as H-beams, track steels, etc.), the working layer of the rolls needs to have good machinability to ensure the accuracy of the roll shape and the stability of the rolling process.
The economic and technical balance of roll selection
Due to the high procurement and maintenance costs of rolls, the best balance point between technical performance and economy needs to be found when selecting the type. For example:
Casting vs. forging: Casting rolls have a lower cost and are suitable for general working conditions. Forged rolls have higher strength and are suitable for high-load rolling mills.
Alloy vs. non-alloy: Alloy rolls (such as high-chromium cast iron, high-speed steel) have better wear resistance, but they are more expensive.
Single material vs. composite material: Composite rolls (such as high hardness on the outer layer + high toughness on the core) can balance wear resistance and fracture resistance.
Conclusion
The performance selection of rolls directly affects the rolling efficiency, product quality and equipment lifespan. Enterprises should, based on specific rolling processes, product requirements and cost budgets, rationally select the material of rolls and manufacturing processes to achieve the best production efficiency.
E-mail：cykc@cykcgroup.com.cn