Spheroidal Graphite Iron (SG / GGG / EN-GJS) Roll Core Material

Spheroidal Graphite Iron (SG / GGG / EN-GJS) is the standard core material used in centrifugal cast rolling mill rolls. It provides the mechanical strength and toughness required to support the working shell under demanding rolling loads.

The microstructure consists of a ferritic-pearlitic matrix with nodular graphite, providing good ductility and resistance to crack propagation. This enables the core to withstand mechanical loads and significantly reduces the risk of roll breakage.

In centrifugal cast rolls, the SG core provides internal support and stability. A sound metallurgical bond is formed during casting, ensuring continuity between shell and core under combined mechanical and thermal loads.

SG core material is used across various centrifugal cast roll types, including indefinite chill, high chromium and high speed steel rolls, where surface performance must be balanced with mechanical reliability. It is also used in centrifugal cast SG iron rolls, where both shell and core belong to the same material family but differ in hardness, alloying level and resulting mechanical properties.

SG iron is not used as the core material in centrifugal cast steel rolls. Instead, the core is produced from lower alloyed cast steel, ensuring compatibility with the shell and adequate mechanical strength.

Spheroidal Graphite Iron (SG / GGG / EN-GJS) roll core microstructure showing nodular graphite in pearlitic-ferritic matrix at 100x and 200x magnification Typical hardness gradient for Spheroidal Graphite Iron (SG / GGG / EN-GJS) roll core material showing Shore C hardness versus depth from surface
Grade SG Roll Core Material
Typical Matrix Ferritic-Pearlitic
Graphite Presence Present (Nodular / Spheroidal)
Hardness Range (ShC) 35 - 55
Tensile Strength (MPa) 500 - 700
Yield Strength (MPa) 300 - 450
Elongation (%) 3 - 7
Primary Function Load-bearing strength and resistance to roll breakage

Cast Rolling Mill Rolls and Related Materials

You can also consult our pages on Cast Rolling Mill Rolls and Centrifugal Cast Rolls.

In addition, you may refer to our dedicated pages covering the main cast roll material families:

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