Spheroidal Graphite (S G) Iron Rolls
Spheroidal Graphite Cast Iron (S G Iron) or Ductile Iron is considered as one of the most versatile roll materials now a days. It is produced by a small proportion of magnesium added to the melt as nickel-magnesium or alternative alloy, or as pure magnesium. In S G Iron Roll, the free carbon takes the shape ofspheroids or nodules, thereby eliminating the notch effect of flake 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 are specially adapted for roughing and intermediate plate mills and rod or bar mill roughers. As a result of the spheroidal form of the graphite, S G Iron Rolls are much stronger than rolls of the clear-chill type and the gradual fall in hardness is an added advantage. As such, these rolls are particularly suitable for Skelp and Strip Mills, also Bar Billet Mills, and are being increasingly used for other applications.
S G Iron rolls are further classified into 2 categories:
- Pearlitic S G Iron Rolls:
These are specifically good for small section and flat rolling. There is also some use of pearlitic S G Iron Rolls in conditions in which the first essential is toughness, rather than wear-resistance, e.g. rolls for heavily loaded roughing stands.
- Accicular S G Iron Roll:
These rolls are most suitable for heavier section where added strength and depth of hardness are required. Sand-cast accicular S G iron is employed for certain special-purpose rolls, e.g. pilger rolls.
The iron is alloyed with nickel and molybdenum, to permit formation of an accicular structure in the as-cast condition.
DPIC Chill Rolls (Double Poured indefinite Chill)
The working surface of DPICC rolls gives a hard layer which confers good resistance to wear. The core and neck are made upon steel shaft in specialized double poured centrifugally cast chill rolls barrels.
Compared to grey iron, white chill iron is less soft, strong and incapable of withstanding high dynamic stresses, but owing to its greater hardness, has better wear-resistance, and has high compressive strength. It retains a fair proportion of its strength at elevated temperature, for example, in hot rolling. These make it excellently work for steel re-rolling mills, semi-automatic or Automatic plants, Wire roll plants, TMT plants, Roughing mill rolls, Intermediate mill rolls for two, three and four-high mills, turning out of high grade ferrous and non-ferrous sheet and strip or section. High Alloy Clear Chill Rolls have proved well suited for the finishing stand of rod and light section mills, for continuous small and medium hot strip mills, and for strip mills of older design.
Composite Iron Rolls (Double Poured Iron Rolls)
The inherent advantage of the steel and chill rolls respectively made way for something in between whereone can get higher hardness and toughness with better roll-strength. Thus, here, the conventional compositerolls are produced by a special double-pour casting method in which two independent zones – a shell ofhighly alloyed iron & another a softer graphitic-grey iron core are achieved.
In newly installed up-to-date mills, high speed and heavy reduction rolling is performed and the rolls of topmost quality combining high strength with good wear resistance and deep hardness penetrations are instantly required to meet the highest grade of surface finish on the rolled sheet.
ICCI Chill Iron Rolls (Indefinate Chilled Cast Iron)
Indefinite Roll is cast using such proportions of silicon, chromium, nickel and molybdenum that the working face is no longer completely white but contains a small amount of very finely divided graphite flakes gradually increasing from face to core with corresponding decrease in the amount of carbide. The rolls are to ensure minimum sacrifice of clear chill while achieving maximum functional depth.
Indefinite Chill Rolls are superior in biting performance and have enough strength and resistance against thermal shock occurring at the time of accident in the rolling operation compared to Clear Chill Rolls.
Roll of this type have hardness up to about 70 Shore °C can be grooved for use in roughing and finishing stands, for processing sections such as T-bars and U-sections, and for roughing and intermediate rolls of wire and rod mills.
Steel Shaft Fitted Double Poured Chill Rolls
Steel Rolls ‘as-cast’ without heat treatment are not suitable for rolling. Dendritic structure, coarse grain, non-homogeneity and internal stresses make it poor in mechanical properties. So these rolls are subjected toprecisely calculated & controlled heat treatment, thereby distributing wildly scattered Cementite / Ferrite more evenly while retaining the basic Pearlitic structure so important to Alloy Steel Rolls.
Such rolls have higher strength at the cost of hardness decrease compared to Chill or S G Iron Rolls, makingthem suitable for heavier passes and severe stress in the roughing & intermediate stands.
Alloy Cast Steel Rolls
They are chiefly applied for the mills where the strength or biting quality is taken into further considerationthan wear resistance. A wide range of Alloy Cast Steel Rolls have been developed to meet individual applications, depending on their carbon content and heat treatment.
Alloy Steel Base (Adamite) Rolls
Their performance in rolling operation is generally placed in the middle way, lying between the quality of Alloyof Steel Rolls and that of S G Iron Rolls. The rolls are heat treated for many hours under the rigid control of metallurgical standard. Their resistance to wear and abrasion of the rolls is quite excellent. These rolls are incomparable for rolling Rails, Angles, Channels, and Beams, where deep passes are necessary. They are specially recommended for high tonnage of Billet, Sheet Bar and Rails and where very long rolling period is required. They are extensively used for heavy duty work, such as blooming and slabbing.
FORGED ROLLS manufactured by our principles can be offered for the following applications.
Flour Mills, Rubber Mills, Sugar Mills, Hot Rolling Of Steel, Copper Rolling, Plate Rolling, Hot Rolling of Steel, Cold Rolling of Stainless Steel, Flour Mill, Copper Rolling, Aluminum Rolling, Conveyer Rollers, Rubber Mills, Sugar Mills, Plate Rolling, Plate Bending.