Difference between carbide roll rings for High-speed wire rolling and High-strength bar rolling

In the field of metal processing, wire rolling is the core process for producing high-precision metal wire and bar. With the continuous improvement of rolling speed and precision requirements, the limitations of traditional rollers have become increasingly prominent - high-speed steel rollers are easy to wear and alloy cast iron rollers are not accurate enough. With its ultra-high hardness, heat resistance and fatigue resistance, cemented carbide (WC-Co) roller rings have become a key breakthrough for the upgrading of modern wire/bar rolling equipment.

However, there are significant differences in material selection, structural design, use conditions and performance requirements between cemented carbide roller rings used for rolling high-speed wire (high-speed wire) and high-speed bar (bar). The main differences and technical analysis of the two are as follows:

1. Material composition and microstructure

High-speed wire rolling roller ring

High wear-resistant cemented carbide (WC-Co) is usually used, with a low cobalt (Co) content (6%-15%) and fine tungsten carbide grains (0.2-0.5μm) to improve surface hardness and wear resistance. For example, finishing mills usually use low cobalt (8%-10%) and fine grain grades (such as YGR55) to meet the wear resistance requirements during high-speed rolling (line speed ≥80m/s).

High-strength bar rolling roller ring

Due to the large rolling load and impact force of bars, high bending strength and toughness are required. The cobalt content is usually high (15%-30%), and the tungsten carbide grains are coarse (5-6μm).

2. Structural design and manufacturing process

High-strength wire roller ring

Mostly integral carbide structures with small diameters (Φ200-400mm), suitable for the compact space of finishing mills. Through the hot isostatic pressing (HIP) sintering process, the density is ensured to be >99.8%.

TMT Bar/Rebar roller ring

Usually adopts a composite structure: the outer layer is cemented carbide (WC-Co), and the inner layer is a tough material (such as ductile iron), connected by metallurgical bonding or mechanical keys.

3. Cooling and thermal management

High-strength wire roller ring

Due to the high rolling speed (80-120m/s), rapid heat dissipation is required to avoid thermal fatigue cracks. High-pressure atomization cooling (0.6-0.8MPa) and annular nozzle arrangement are adopted, with a water volume of 15-20m³/h to ensure that the temperature gradient of the roller surface is ≤100℃/mm.

High-strength wire roller ring

The rolling speed is low (20-40m/s), but the rolling force is large, and cooling needs to pay more attention to uniformity. Usually the water pressure is required to be 0.4-0.6MPa, the water volume is 40-50m³/h, and the main nozzle is aligned with the groove outlet to prevent thermal expansion of the core and stress cracking of the outer layer.

4. Rolling parameters and life

High-strength wire roller ring

The rolling volume of a single groove can reach 4000-5000 tons (such as φ5mm wire), the grinding volume is 0.1-0.3mm/time, and the life is 5-10 times that of a high-speed steel roller.

TMT Bar/Rebar roller ring

The rolling volume of a single groove is about 1300-1400 tons (such as φ14mm round steel), the grinding volume is 1.5mm/time, and the life is more than 10 times that of a ductile iron roller, but microcracks need to be checked regularly to prevent roller breakage.

5. Application scenarios and special needs

High-strength wire roller ring

Focus on surface finish (Ra≤0.2μm) and dimensional accuracy (tolerance ±0.05mm), suitable for high value-added products such as automotive spring steel wire and 810 welding wire.

TMT Bar/Rebar roller ring

Need to adapt to materials with high deformation resistance (such as stainless steel and titanium alloy), reduce the tendency of bonding through surface coating (such as CrAlN), and optimize the hole design to reduce the concentration of rolling force.

High-strength wire roller ring focuses on high wear resistance and high precision, while TMT Bar/Rebar roller ring emphasizes impact resistance and composite structure design. The difference between the two stems from the fundamental differences in rolling speed, load type and product requirements. Future trends include the application of gradient materials, intelligent temperature control and low-carbon manufacturing technology to further improve comprehensive performance. Hunan Tianyi High-tech Materials Manufacturing Co., Ltd. escorts the rolling mill.