SGI Rolls

SPHEROIDAL GRAPHITE IRON ROLLS Spheroidal Graphite Cast Iron (SG Iron) or Ductile Iron is considered as one of the mostversatile roll materials now a days. It is produced by a small proportion of magnesium added tothe melt as nickel-megnesium or alternative alloy, or as pure magnesium. In S G Iron Roll, thefree carbon takes the shape of spheroids or noudles, there by eliminating the notch effect offlake graphite and improving upon the mechanical properties of the cast iron.

S.G. Iron rolls are so superior in wear resistance to that of Cast Steel Rolls that they arespecially adapted for roughing and intermediate plate mills and rod or bar mills roughers. As aresult of the spheroidal for of the graphite, SG Iron Rolls are much stronger than rolls of theclear chill type and the gradual fall in hardness is an added advantage. As such, these rolls areparticularly suitable for Skelp and Strip Mills, also Bar Billet Mils, and are being increasinglyused for other applications. The structure of SG Iron Rolls consists of transformed austenite(pearlite) eutectic carbide and spheroidal graphite. Spheroidal Graphite Iron Rolls may havepearlitic matrix or, if relatively large amount of alloy elements are present the structure may beacicular or martensitic.

Pearlitic Rolls: These are specifically good for small section and flat rolling. There is also someuse of pearlitic SG Iron is toughness, Rolls in conditions in which the first essential rather thanwear resistance, e.g. rolls for heavily loaded roughness stands.