Dynamic Rolls

Malerkotla, Sangrur, Punjab

The Working surface of clear chill rolls shows the white graphite free structure consisting of eutectic carbide and transformed austenitne. This gives a hard layer which confers good resistance to wear. Flake graphite is embedded in a matrix of pearlite containing about 0.08% of combined carbon. Compared to grey iron, white chill iron is less soft, strong & incapable of withstanding high dynamic stress, but owing to its greater hardness, has better wear resistance, and has high compressive strength. These make excellent work rolls for two, three and four mills, turning out of high grade ferrous and non-ferrous sheet and strip or section.

Spheroidal Graphite Cast Iron (SG Iron) or ductile iron is considered as one of the most versatile roll material now a days. Rolls has greatly improved properties, including high tensile strength of more then 40kg/mm2 compared to that of 20-30 kg/mm2 of cast iron. These are specifically good for small section and flat rolling. These rolls are most suitable for heavier section where added strength and depth of hardness are required. Stand-Cast acicular S.G. iron is employed for certain special-purpose rolls. eg. pilger rolls.

These rolls have hard alloy iron on the working layer and soft grey iron or SG iron core depending upon the application. The shell matrix with proper distribution of carbides and graphite imparts high wear resis- tance, stability in shape and good surface finish. The softer core ensures good mechanical properties and resistance to thermal & mechanical loads.

The structure consist of graphite nodules in the matrix of bainite. These rolls have high hot strength combined with good wear resistance. Sufficient water cooling is a must for satisfactory.