Backup Roll for Rolling Mill — Work Roll Support
The backup roll is used to support the work roll or intermediate roll to avoid the deformation of work roll and affect the yield and quality of rolled steel.
Introduction
The backup roll is a roll that supports the work roll, and contacts the rolled parts through work roll so as to reduce the diameter of work roll and enhance the rigidity of work roll. The backup roll plays a vital role in the rolling mill to support the work roll or intermediate roll in purpose of avoiding deflection of the work roll and affect on the yield and quality of the plate and strip rolling mill. The quality characteristics of the cast steel backup roll are high surface hardness, good hardness uniformity and deep hardened layer of roll body, good strength and toughness of roll neck and roll body; the backup roll has high wear resistance and peeling resistance, strong anti-accidents.
Backup roll for rolling mill has cast steel roll and forged steel roll. For some small mills, the forged steel backup rolls of 1000mm or less are made of 86CrMoV7 and 9Cr2Mo, its carbon content is 0.80% to 0.95% and Cr content is 2%.
The steel for Cr4 and Cr5 backup rolls has a carbon content of 0.4% to 0.6% and a Cr content of 4% to 5%. The hardened, wear resistance, peeling-resistant, fatigue-resistant and anti-accident properties of the backup rolls basically eliminate the peeling phenomenon of the roll body surface and the roll cutoff accident. Cr4, Cr5 steel backup rolls are suitable for high-speed steel and semi-high-speed steel work rolls.
Advanced Metallurgy: By utilizing high-purity alloy steels (such as Cr4 or Cr5) and vacuum degassed melting, we minimize non-metallic inclusions, significantly reducing the risk of sub-surface fatigue cracking and spalling.
If your mill runs a mixed material program — switching between HSS, Adamite, and high-chromium for different stands — see our roll material comparison guide for a side-by-side breakdown of wear rate, thermal resistance, and cost-per-tonne by application.
FAQ
Which backup-roll grade family should I specify for my mill?
Two families: forged 86CrMoV7 / 9Cr2Mo for mills under 1000 mm (carbon 0.80–0.95%, Cr around 2%), and cast Cr4 / Cr5 for larger mills (carbon 0.4–0.6%, Cr 4–5%). Grade choice follows your work-roll grade and stand position.
How do I match the backup-roll grade to my work-roll grade?
If your work rolls are HSS or semi-HSS, specify Cr4 or Cr5 cast backup rolls (matched grade). If your work rolls are Adamite or high-chromium iron, forged 86CrMoV7 backup rolls are the typical pairing. Small mills under 1000 mm typically run forged 86CrMoV7.
What surface characteristics should a backup roll deliver?
High surface hardness with good hardness uniformity and a deep hardened layer across the roll body, plus strength and toughness at the roll neck and body. The exact hardness target is set from your stand position and strip material — send both in the RFQ and we respond with the target.
How is backup-roll spalling and sub-surface fatigue cracking controlled?
We use high-purity Cr4 / Cr5 alloy steel with vacuum-degassed melting to minimize non-metallic inclusions, which reduces the risk of sub-surface fatigue cracking and spalling. Ask for the melting and cleanliness route in the RFQ.
What does TINVO need in a backup-roll RFQ?
Stand position, work-roll grade, strip material range, strip width range, target roll-change interval, and surface hardness requirement. Drawings (if available) accelerate the response.
Related Reading
Customization
In rolling-mill procurement, backup roll grade selection drives both cost-per-tonne and roll-change frequency. The right backup-roll specification — Cr4 cast, Cr5 forged, or 86CrMoV7 for smaller mills — is typically settled alongside work-roll grade choice and stand-position assignment. TINVO supplies backup rolls matched to your mill’s stand sequence and rolling-schedule intensity; share your stand map and rolling program in the RFQ and we respond with a grade-range recommendation.