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The highly stressed rolls must offer a high hardness and wear resistance with the lowest possible tendency to pick up. Rolls made from cold work tool steels are most suitable for these applications.
Due to the very high-pressure loads occurring during the straightening of round bar material, the journals of the rolls are highly stressed.
In order to improve the resistance to breakage, two alternative hardening processes are available at Bowers & Jones:
Black and Bright Bar
Tubes and Pipes
Sections and Rails
ZESEK EXTRA is a further development of the well-known tool steel ZESEK with similar chemical composition but with a more homogeneous microstructure.
Due to the fine and more homogenous structure (See Fig. 2) the chipping resistance has been enhanced for a longer roll life.
Because of the better distribution of primary carbides the abrasive wear resistance is slightly better compared to conventional W. Nr. 1.2379 by using Bowers & Jones special heat treatment the steel can also be used in selected hot rolling applications.
ZESEK, W. Nr 1.2379 (~AISI D2) is a forged ledeburirtic high carbon chrome cold work tool steel alloyed with Mo and V.
Compared to cast D2, ZESEK has no porosity or other casting defects which increases its crack resistance.
Conventional W.Nr. 1.2379
(AISI D2) with typical lines of primary carbides.
ZESEK EXTRA with better distributed primary carbides
Through hardening of the rolls with the journals tempered back
Surface hardening of pre-heat treated rolls (depth of hardness approx. 10-25 mm)
For some applications, composit rolls are offered as a two part design: the working part of the roll is a shell made from ZESEK or ZESEK EXTRA fitted onto a shaft made from tough engineering steel.
The choice of the best suitable option depends on customers' requirements.
A combination of ZESEK materials and our specific heat treatment processes gives Bowers & Jones rolls a much better stability compared to cast materials.
Customers then benefit from a better performance and much lower service life costs.
Our machinery range allows us to manufacture extra-large rolls up to 1350mm diameter roll body and up to 5000mm length shafts, with a combined weight of upto 8 tonnes.
Our technical staff will be happy to give you further advice on design and material selection.