Core and Necks of Rolls

In case of monobloc rolls, core and necks are made of the same material as the barrel. Diff erent types of steels and nodular cast irons are obtained according to technical requirements. Properties are achieved by optimising cooling while casting and subsequent heat treatment. Core and necks of compound rolls are made of lamellar or nodular cast iron. In the case of nodular cast iron a suitable quantity of inoculations is used. During casting, re-melting among diff erent metals is strictly controlled to avert cast iron dirtying. In the production of rollers and/or sleeves, the core can be cast in graphitic steel.

Mechanical properties
TYPEHARDNESS (ShC)TENSILE STRENGTH (MPa)BENDING STRENGTH (MPa)Impact
resistance
(J/m2* 104)
MODULUS OF ELASTICITY (GPa)
CAST STEEL 30÷50 500÷1000 800÷2000 5÷15 ~200
NODULAR CAST IRON 35÷45 400÷800 600÷1400 2÷8 ~180
Mechanical properties
TYPEHARDNESS (ShC)TENSILE STRENGTH (MPa)BENDING STRENGTH (MPa)Impact
resistance
(J/m2* 104)
MODULUS OF ELASTICITY (GPa)
LAMELLAR CAST IRON (L) 35÷50* ~250 ~500 ~2.5 ~130
NODULAR CAST IRON (N) 35÷50* ~400 ~700 ~3.0 ~170
GRAPHITIC STEEL (AG) 40÷50 ~600 ~1000 ~3.5 ~200
Microstructure of roll materials
LAMELLAR CAST IRON (50x)NODULAR CAST IRON (50x)GRAPHITIC STEEL (50x)
Characteristics
In the case of monobloc rolls, microstructure widely ranges depending on diIn the case of monobloc rolls, microstructure widely ranges depending on diff erent carbon content in this category of products. Guaranteeing toughness and suitable mechanical resistance is key to meet the mill application requirement. In the case of compound rolls there are three different types of material (see fi gures above). The lamellar cast iron has a prevalently pearlitic matrix in which lamellar graphite is present. The nodular cast iron has a prevalently pearlitic-ferritic matrix in which nodular graphite is present. In the case of graphitic steel a part of carbon precipitates as nodular graphite into a pearlitic matrix.

Core and Necks of Rolls data sheet

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