Material Grade: Cr3, Cr5

Hot & Cold Rolling Mill Alloy Steel Backup Rolls (Cr3 & Cr5 Rolls)

Engineered for high-rigidity applications requiring exceptional resistance to contact fatigue and thermal shock. The Cr series utilizes a high-chromium alloy steel matrix (up to 5.40% Cr) to provide a stable support structure for work rolls, helping to maintain precise strip profiles under intense contact pressure in hot and cold flat rolling.

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By Application

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Key Mill Applications (Recommended Stands)

Hot Strip & Heavy Plate Mill Backup Rolls

Applicable Grades: Cr3, Cr5

Focus: Designed as high-performance backup rolls for hot strip mills and heavy plate mills. Exhibits extreme fatigue strength and superior anti-spalling properties to safely withstand massive rolling tonnage without shell peeling.

Cold Strip & Skin Pass Mill Backup Rolls

Applicable Grades: Cr5

Focus: Engineered for high-precision backup rolls in cold rolling mills and temper/skin pass mills. Excellent depth of hardness layer ensures minimal elastic deformation, maintaining long-term strip flatness and thickness control.

Heavy Reduction Hot Roughing Stands

Applicable Grades: Cr3

Focus: Optimized for initial heavy roughing work rolls in hot strip and medium plate lines. High structural integrity and thermal shock resistance successfully prevent thermal cracking during continuous slab reduction.

Chemical Composition & Physical Properties

DURON’s Alloy Steel Backup Rolls (Cr3 & Cr5 Rolls) are engineered to support exceptional structural stability and extended campaign life. We optimize the deep-hardening characteristics and contact fatigue life through precise micro-alloying with Molybdenum and Vanadium, ensuring consistent matrix hardness profiles. By implementing controlled heat-treatment practices, these heavy-duty alloy steel backup rolls resist sub-surface shear stress and minimize fatigue-induced spalling. The chemical compositions and metallurgical specifications for these alloy steel backup rolls are detailed below:

Code (代码)	C	Si	Mn	Cr	Ni	Mo	V	Hardness (Barrel HSD)
Cr3	0.20-0.50	0.20-0.70	0.50-1.30	2.40-3.50	≤ 0.80	0.30-0.60	0.05-0.20	58-63
Cr5	0.30-0.55	0.20-0.70	0.30-1.10	4.70-5.40	≤ 0.50	0.50-0.85	0.15-0.40	68-73

* P ≤ 0.08, S ≤ 0.05.
* Neck Hardness: ≤ 40 HSD for both grades.

Metallurgical Excellence

Why Choose DURON Alloy Steel Backup Rolls?

- Deep and Uniform Hardness Layer: Advanced differential heat treatment allows our alloy steel backup rolls to maintain a reliable, predictable hardness gradient deep into the usable diameter, extending total mill dressing cycles.
- Resistance to Contact Fatigue Spalling: The refined micro-alloyed matrix minimizes sub-surface micro-crack initiation under intense cyclic loading, reducing the risk of catastrophic shell spalling in 4-hi and 6-hi mill configurations.
- Robust Structural Core Integrity: Precision forging or casting protocols guarantee a tough core microstructure with high yield strength, effectively eliminating the risk of roll neck distortion or thermal fatigue breakage.
Mill Stand Roll-Pairing Synergy: For balanced deflection control and stable strip profiles across the rolling line, heavy plate and hot strip mill operators frequently pair these Cr-alloyed backup rolls with our high-hardness Centrifugal High Chrome Cast Iron Rolls or wear-resistant Indefinite Chilled Rolls in the working positions.

Manufacturing Control & Inspection

100% Non-Destructive Testing

Every roll undergoes rigorous Ultrasonic Testing (UT) at the working layer and bonding zone to eliminate internal voids and ensure structural integrity under heavy loads.

Precision CNC Machining

Roll necks and barrel profiles are machined using heavy-duty CNC equipment, strictly adhering to your drawing's dimensional and runout tolerances for perfect bearing fitment.

Metallurgical Verification

Chemical compositions are analyzed via spectrometer pre-pouring, and multi-point hardness mapping is conducted post-heat treatment to guarantee the specified hardness gradient.

Quality Traceability

All dispatched rolls are accompanied by a comprehensive inspection certificate, documenting chemical composition, hardness distribution, and UT reports.