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WALZEN IRLE Materials - Overview
Steel- and Iron-Industry
The following listed roll materials represent the special WALZEN IRLE material index of rolls designed for the Steel- and Iron-Industry.
It results from over 180 years of experience in hundreds of thousands successfully done orders for nearly every thinkable industrial rolling application.
Regarding stability, surface hardness and wear resistance properties all following roll materials can be adjusted to the customers specific mill conditions.
K — Chilled Cast Iron - Single Poured
K — Chilled Cast Iron - Compound
I — Indefinite - Compound Casting
SP — Single Poured and Compound
SA — Single Poured and Compound
SP/A H — Single Poured
CR — Chrome Iron
ST — Steel Casting
STG — Steel Casting Graphite
SST — Special Steel
K — Chilled Cast Iron - Single Poured
Microstructure and main properties
Single poured chilled cast iron rolls consist of a hardened layer of white cast graphite free cementite and the metallic matrix. The thickness of the usable chilled layer can be up to 20 mm depending on the roll diameter. The core material is grey solidified and consists mainly of a perlitic matrix with lamella graphite. Between the outer chilled shell and the core there is a mottled iron zone consisting of grey and white solidified microstructures.
The surface hardness and the wear resistance of the chilled cast iron is determined by the amount of ledeburit in the microstructure and the structure of the matrix. A perlitic, bainitic or martensitic matrix can be obtained using special alloying elements. An increase in the hardness and wear resistance will cause a decrease in the thermal and mechanical capability. The quality grade K30 describes the proportion of cementite in the microstructure.
Typical applications:
Section Mills
- Intermediate and Finishing Stands of Wire, Bar and Small Section Mills
- Rolls for Straightening Mills
- Stretch Reducing Rolls for the Tube/Pipe Production
Flat Rolling Mills
Work Rolls for
- Two-high and Three-high Stands of Sheet Mills, especially for tool- and stainless steel sheets
K — Chilled Cast Iron - Compound
Microstructure and main properties
Compound poured chilled cast iron rolls consist of a hardened layer of
white cast graphite free cementite (ledeburit) and the metallic matrix.
The surface hardness and wear resistance is defined by the amount of
cemintite in the matrix and the formation of the metallic matrix.
A perlitic, bainitic or martensitic matrix can be obtained using
special alloying elements. An increase in the hardness and wear
resistance will cause a decrease in the thermal and mechanical
capability.
The quality grade K30 describes the proportion of cementite in the microstructure.
The thickness of the wear resistant coating on the compound rolls can
be adjusted according to the degree of utilization . The core and
journal material of the compound roll can consist of grey cast iron (G)
or nodular iron (S).
The strength and bending strength of the roll can be adjusted according to the different operating conditions.
Typical applications:
Section Mills
- Intermediate and Finishing Stands of Wire, Bar and Small Section Mills
- Rolls for Straightening Mills
- Stretch Reducing Rolls for the Tube/Pipe Production
Flat Rolling Mills
Work Rolls for
- Two-high and Three-high Stands of Sheet Mills, especially for tool- and stainless steel sheets
I — Indefinite - Compound Casting
Microstructure and main properties
The essential feature of the indefinite roll is a microstructure which is aimed from the roll surface towards the roll core.
The microstructural components cementite and graphite are arranged in a cellular way vertically to the roll surface.
The graphite proportion continuously increases from the barrel surface
to the barrel core and the proportion of free cementite decreases in
the same direction.
The metallic basic matrix of indefinite rolls is formed perlitic or
bainitic in the hardness range of 340-540 HV. Due to the special matrix
and the continuous decrease of hardness from the barrel surface towards
the core, indefinite rolls with a surface hardness of up to about 540
HV are suitable for indenting of deep calibres.
Indefinite rolls of up to 540 HV are mainly applied as single poured rolls.
In case they are exposed to high wear and mechanical or thermal loads
they can also be manufactured as statically poured or centrifugally
cast compound rolls with grey cast iron- or nodular iron cores.
Typical applications:
Section Mills
- Intermediate and Finishing Stands for Medium Section Mills
- Roughing and Intermediate Stands of Wire and Small Section Mills
- Tube Straightening and Detaching rolls
- Intermediate and Finishing Stands of Wire, Bar and Light Section Mills
Flat Rolling Mills
Flat rolling mills require mainly double poured Indefinite chill rolls.
Work Rolls for
- Heavy and Medium Plate Mills
- Two-high and Three-high Stands for Sheet Mills
- Finishing Stands (F4-F7) of Wide Hot Strip Mills
- Roughing and Finishing Stands of Medium, Heavy Plate Mills and Steckel Mills
- Two-high and Three-high Stands of Sheet Mills
- Skin Pass Mills for Hot and Cold Strip
- Finishing Stands of Medium and Heavy Plate Mills
- Finishing Stands of Steckel Mills
- Finishing Stands of Medium and Narrow Hot Strip Mills
- Skin Pass Stands for Hot Strip Mills
Back-up Rolls for
- Skin Pass Mills for Cold Strip
SP — Nodular Iron - perlitic, Single Poured and Compound
Microstructure and main properties
In nodular cast iron rolls the graphite has a nodular function, which
causes significant increase in mechanical strength and ductility
compared to grey lamella qualities. Apart from the nodular graphite and
depending upon the required wear resistance, variable amounts of
cementite in the microstructure can be found.
The amount of cementite decreases from the barrel surface to the core
of the roll and the nodular graphite simultaneously increases.
Nodular cast iron rolls are used mainly as single-poured rolls. In case
of especially high wear resistance demands and mechanical or thermal
resistance, they can be manufactured as statically cast or as
centrifugal cast compound rolls with a high strength nodular core.
Typical applications:
Section Mills
- Blooming and Billet Stands
- Roughing and Intermediate Stands for Wire, Bar and Small Section Mills
- Intermediate and Finishing Stands for Medium Section and Heavy Section Mills
Flat Rolling Mills
Work Rolls for
- Roughing and Intermediate Stands for Medium and Narrow Strip Mills
SA — Nodular Iron - acicular, Single Poured and Compound
Microstructure and main properties
In nodular cast iron rolls the graphite has a nodular function, which
causes significant increase in mechanical strength and ductility
compared to grey lamella qualities.
Apart from the nodular graphite and depending upon the required wear
resistance, variable amounts of cementite in the microstructure can be
found. The amount of cementite decreases from the barrel surface to the
core of the roll and the nodular graphite simultaneously increases.
The metallic matrix is in SA-nodular cast iron rolls acicular. The
acicular matrix is adjusted by alloys of Ni and Mo and compared to the
perlitic matrix it has a higher tensile strength and wear resistance.
The hardness, tensile-strength and viscosity of this material can be
optimally adjusted to the respective applications by tempering- or
start-annealing. In case of especially high wear resistance demands and
mechanical or thermal resistance, the nodular cast iron rolls can be
manufactured as statically cast or as centrifugal cast compound rolls.
Typical applications:
Section Mills
- Intermediate and Finishing Stands of Wire, Bar and Small Section Mills
- Rolls for Slit Passes of Wire Rod Mills
- Finishing Stands of Medium Section and Heavy Section Mills
Flat Rolling Mills
Work Rolls for
- Roughing and Intermediate Stands of Narrow and Medium Strip Mills
SP/A H — Nodular Iron - annealed, Single Poured
Microstructure and main properties
In nodular cast iron rolls the graphite has a nodular function, which
causes a significant increase in mechanical strength and ductility
compared to grey lamella qualities.
Apart from the nodular graphite and depending upon the required wear
resistance, variable amounts of cementite in the microstructure can be
found. The matrix is either ferritic/perlitic, perlitic or bainitic.
The ductility and the thermal resistance of the material is increased
by carrying out a special annealing process to the qualities SP/A-280H,
-320H, -360H and -400H.
The heat treatment results in a homogeneous matrix over the whole roll cross section with a low radial hardness loss.
The nodular cast iron rolls SP/A -280H, -320H, -360H and -400H can be
annealed for the manufacture of larger roll profiles in a
pre-calibrated condition. This means that hereby on the roll surface,
pressure residual stress can be fixed even in deeper calibre cuts,
which counteracts cracking.
Typical applications:
Section Mills
- Blooming and Slabbing Stands
- Roughing Stands for Heavy and Medium Section Mills
- Roughing, Intermediate and Finishing Rolls for semi finished products
- Roughing Stands of Wire, Bar and Small Section Mills
Flat Rolling Mills
- Edger Rolls for Hot Strip Mills
CR — Chrome Steel - Chrome Iron
Microstructure and main properties
The microstructure of the wear resistant chrome cast alloys consists of
chromium rich eutectic carbides of the M7C3 or M23C6 type, in a matrix
of pearlite or martensite with finely dispersed secondary carbides.
Due to the special structures of the CR-carbides the chrome cast
materials have far superior mechanical strength and higher ductility in
comparison to other carbide materials.
Further positive properties are high pressure and thermal resistance.
The amount of Cr-carbides in the Cr-material is variable in a wide
range. Increasing amounts of Cr-carbides increase the wear resistance
and on the other hand ductility and mechanical strength decreases. The
quality grade CR5 describes the proportional amount of eutectic
Cr-carbides in the microstructure. By using heat treatment and
depending upon the amount of Cr-carbides, surface hardness of up to 700
HV can be reached. The decrease in hardness in the usable shell layer
is very low.
For use in the flat rolling mills, the Cr-rolls are only manufactured
as centrifugal cast compound rolls with grey cast iron or nodular iron
cores. For profile roll mills they are used as single-poured rolls.
Typical applications:
Section Mills
- Roughing, Intermediate and Finishing Stands of Light and Medium Section Mills
- Straightening Rolls for Tubes/Pipes and Bars
- Forming Rolls for Tubes and Pipes
- Sizing Rolls for Tubes and Pipes
Flat Rolling Mills
Work Rolls for
- Finishing Stands (F1-F4) of Wide Hot Strip Mills
- Finishing Stands of Steckel Mills
- Finishing Stands of Medium and Heavy Plate Mills
- Roughing and Intermediate Stands of Wide Hot Strip Mills
- Roughing Stands of Steckel Mills
- Roughing Stands of Medium and Heavy Plate Mills
- Roughing and Finishing Stands of Medium and Narrow Strip Mills
- Skin Pass Mills
- Two-high and Three-high Stands for Sheet Mills
ST — Steel Casting
Microstructure and main properties
Depending upon the chemical composition and heat treatment steel cast
rolls have a perlitic or bainitic matrix. The main alloying elements
are Cr, Ni, Mo, V and W which depending upon the application of the
roll are additionally alloyed in various amounts.
The description ST-0 is valid for under eutectoid to near eutectoid materials with a C-content <0,8 %.
These materials are distinguished by high strength and breaking strength.
The surface temperature of the steel cast roll is adjusted by the type
of heat treatment and the chemical composition and can be in the range
of 180 - 420 HV.
The decrease in hardness within the working layer is negligible.
Steel cast rolls can be annealed in a pre-calibrated condition for the
manufacturing of larger profiles. This means that hereby on the roll
surface, pressure residual stress can be fixed even in deeper calibre
cuts, which counteracts cracking. Apart from that, this special
annealing achieves lower hardness loss and thereby good wear resistance
up to the end diameter of the roll.
Typical applications:
Section Mills
- Blooming and Slabbing Stands
- Roughing, Intermediate and Finishing Stands of Heavy Section Mills
- Roughing and Intermediate Stands of Wire and Small Section Mills
- Finishing Stands for Special Sections with deeper Passes
- Billet Mills and Stands for semi finished products
- Intermediate and Finishing Stands of Medium and Heavy Section Mills
- Intermediate and Finishing Stands of Small Section Mills
- Horizontal and Vertical Rolls for Universal Stands
- Edger Stands of Section Mills
- Pilger Rolls for Tube Mills
Flat Rolling Mills
- Edger Rolls for Hot Strip Mills
Back-up Rolls for
- Roughing and Finishing Stands of Medium and Narrow Hot Strip Mills
The back-up rolls can be supplied either as monocast rolls or steel-compound rolls depending on the dimensions.
STG — Steel Casting Graphite
Microstructure and main properties
The graphited steel cast iron rolls are associated with the over eutectoid materials due to their C-content.
By carrying out a specific treatment to the steel cast, a part of the
carbon content is released when solidifying as free graphite.
Essential alloying elements are Si, Cr, Mn, Ni and Mo which depending
upon the application of the roll are additionally alloyed in varying
amounts.
The matrix of the graphited steel cast rolls STGO consists of a perlitic matrix , with max. 5 % carbide and graphite.
The proportion of carbide and graphite can be adjusted from the
chemical composition and the type of heat treatment. Thereby adjusted
to the thermal and the wear resistance of the material and the
application.
Graphited steel cast rolls are distinguished in comparison to the graphite free rolls as follows:
-
high cracking resistance
- good wear resistance
- good surface conditions.
The good material properties of the graphited cast steel roll can be
additionally improved by annealing in a pre-calibrated condition. This
means that hereby on the roll surface, pressure residual stress can be
fixed even in deeper calibre cuts, which counteracts cracking. Apart
from that, this special annealing achieves lower hardness loss and
thereby good wear resistance up to the end diameter of the roll.
The surface hardness of the STGO rolls can be adjusted in the range of 180 - 380 HV.
Typical applications:
Section Mills
- Blooming and Slabbing Stands
- Roughing and Intermediate Stands for Heavy Sections
- Intermediate and Finishing Stands of Medium and Heavy Section Mills
- Intermediate and Finishing Stands of Rail Mills
- Finishing Stands for Special Sections with deeper Passes
- Billet Mills and Stands for semi finished products
- Intermediate and Finishing Stands of Medium and Heavy Section Mills
- Horizontal, Vertical and Edger Stands of Universal Mills
- Roughing and Intermediate Stands of Wire and Small Section Mills
Flat Rolling Mills
Work Rolls for
- Roughing Stands of Hot Strip Mills
- Edger Stands of Hot Strip Mills
SST — Special Steel
Microstructure and main properties
The SST alloyed materials are associated with the high-working-speed steel (HSS).
The main alloying elements are C, Cr, V, W and Mo. The matrix of these
materials consist after the most sophisticated heat treatment of the
martensic elementary matrix in which the carbide of the vanadium (VC)
molybdenum (Mo2C), Tungsten (W2C) and mixed carbide (M6C) can be found
finely distributed. These special carbides are characterized by their
extremely high hardness (up to 3000 HV) and cause these materials to
have a very high wear resistance.
Further positive properties of the SST materials are:
- good tempering properties (up to 550°C)
- high heat stability
- constant hardness throughout the usable roll section
- strongly improved shape accuracy of the products with minimal wear in combination with very good surface structure.
The performance of the rolls compared to the usual qualities can be improved multi-fold (up to 6 x) by using the SST-materials.
Typical applications:
Section Mills*
- Intermediate and Finishing Stands of Light and Medium Section Mills
- Intermediate and Finishing Stands of Wire Mills
- Rings for Horizontal Rolls of Universal Stands
Flat Rolling Mills**
Work Rolls for
- Roughing Stands of Wide Hot Strip Mills
- Finishing Stands (F1-F4) of Wide Hot Strip Mills
- Roughing and early Finishing Stands of Narrow and Medium Hot Strip Mills
* Section Mills: depending on the mechanical loads we recommend spin cast compound rolls (C) with a nodular-iron core (S) or rolls with mechanical mounted mono cast SST-rings on axles.
** For strip mills we deliver SST work rolls as spin cast rolls (C) with a nodular iron core (S).
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