The intermediate roll is a core transmission and support component in the roll system of a tension leveller. Positioned between the work rolls and backup rolls, it plays a vital bridging role. Our intermediate rolls are manufactured from high‑quality GCr15 and 9Cr2Mo alloy steels, widely used in various levelling lines for steel and non‑ferrous metals. Below is a detailed overview of material properties, technical parameters, and typical applications.
1. GCr15 Bearing Steel – Cost‑Effective Wear Resistance
GCr15 is a high‑carbon chromium bearing steel with good wear resistance, ideal for small‑ to medium‑diameter cold rolling rolls.
Key Technical Parameters:
Tempering: HB 270–300
Surface hardness after induction hardening: HRC 61–63
Hardened layer depth: 3–4 mm
Optional hard chrome plating: plating thickness 0.05–0.08 mm
Surface roughness Ra: 0.2–0.4 μm
Typical Application Scenarios:
Cold‑rolled strip tension levelling lines – for stretching and bending straightening of cold‑rolled sheets
Galvanizing / Aluzinc coating lines – e.g., Masteel’s No.6 galvanizing line has adopted GCr15 intermediate rolls (Φ40×2076) with surface hardness HRC 60–62, achieving excellent performance
Colour coating lines – widely used in finishing sections of painted steel sheet production
2. 9Cr2Mo Chromium‑Molybdenum Alloy Steel – High‑Strength & Wear‑Resistant Choice
9Cr2Mo is a dedicated Cr2‑series cold roll steel. The addition of molybdenum significantly improves hardenability and tempering stability.
Chemical Composition (%): C 0.85–0.95, Cr 1.70–2.10, Mo 0.20–0.40.
Key Technical Parameters:
Quenching temperature: 880–900 °C
Surface hardness: HS 90–95 (approx. HRC 62–65)
Hardened layer depth: 6–15 mm
Tempering: HB 280–320
Performance Advantages: After full quenching, the roll surface obtains a high‑hardness martensitic structure, while the core retains tough sorbitic microstructure, providing over 30% higher core toughness compared to surface‑hardened rolls, effectively preventing brittle fracture.
Typical Application Scenarios:
Large‑diameter cold work rolls and backup rolls – suitable for rolls up to 900 mm in diameter
Sendzimir mill intermediate rolls – for multi‑roll mill systems
High‑strength strip levelling lines – where higher strength and wear resistance are demanded
3. Material Comparison and Selection Guide
| Feature | GCr15 | 9Cr2Mo |
|---|---|---|
| Material type | Bearing steel | Cr2‑series cold roll steel |
| Surface hardness | HRC 61–63 | HRC 62–65 |
| Hardened layer depth | 3–4 mm | 6–15 mm |
| Applicable roll diameter | ≤ 200 mm | ≤ 900 mm |
| Wear resistance | Good | Excellent |
| Cost‑effectiveness | High | Superior performance |
Selection Recommendations:
For small to medium diameters and general conditions, choose GCr15 – economical and widely proven in cold levelling, galvanizing, and colour coating lines.
For large diameters and heavy‑load applications, choose 9Cr2Mo – offering superior strength and toughness, ideal for high‑strength strips and large mill roll systems.