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Backup rolls of serial Cr (Cr3, Cr4 and Cr5)
Creatime: 2017-2-3 15:28:36
 

 

Backup rolls for strip steel mill are important element of manufacturing. Bearing the total rolling pressure, the backup rolls were also required to high wear-resistance and fatigue-resistance which had the tight linkage with the production efficiency, the strip shape requirement and the surface quality. Therefore, the backup rolls with above mentioned merits is the ultimate goal of the rolls'' manufacturers.

 

The development of strip mill backup rolls has gone through the alloy nodular iron, the adamite to the serial Cr alloy cast steel rolls at present. With the decreasing of carbon content, the increasing of alloy content and the application of high temperature normalizing and tempering, the structure of backup rolls were optimized, the performance were enhanced continuously that could satisfy the production of strip steel.

 

JiangSu DongYe Roll Co., Ltd. presented the backup rolls of serial Cr alloy cast steel which produced by centrifugal casting. The working layer (outer layer) is the material of Cr3, Cr4 or Cr5, the core part is the material of high strength nodular cast iron so that not only the working layer meets the requirement of high wear-resistance and high fatigue-resistance but the core part satisfies the requirement of high strength to conformity with the rolling requests.

 

Chemical Composition

 
C
Si
Mn
P
S
Ni
Cr
Mo
Working layer (outer layer)
0.3/1.0
0.3/1.0
0.5/1.5
≤0.035
≤0.03
0.3/1.0
3.0/6.0
0.3/1.0
Core
3.0/3.6
1.5/2.5
0.4/0.7
≤0.10
≤0.03
/
/
/

 

Structure and mechanical property

 
Structure
HardnessHSD
Tensile strengthMPa
Working layer (outer layer)
Sorbite + Pearlitic + small amount of Carbide in granulate shape
50-65
≥600
Core
Pearlitic + Ferritic + small amount of Carbide
35-45
≥500

 

Due to be applied the high temperature heat-treatment, the working layer eliminated the network carbide structure so that reduced the brittleness, increased the fatigue-resistance and delayed the occurrence of fatigue flaw as well as prevented the expansion of the flaw, i.e. gained the good performance of anti-stripping and corner breaking.
 
Meanwhile, with the addition of alloy to improve the hardenability of rolls and apply the different cooling specification according to the various operation environment, the working layer gains the perfect hardness, thereby the ideal wear-resistance.  
 
 
 
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