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 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.

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 resistance, 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.