Spheroidal Graphite (Nodular) Cast Iron:

Transcription

1 Product Type Grade of Product Sub Grade SG Iron Pearlitic Accicular Adamite Steel Based Alloy Steel Solid Rolls Graphitic IC Rolls DP Rolls SG Core G I Core ACCI Rolls Spheroidal Graphite (Nodular) Cast Iron: S.G. Iron (Nodular) or Ductile Iron Rolls are available in a wide range of hardness & composition for a variety of application. The matrix structure varies from Ferrito-Pearlitic, Pearlitic to Bainitic & Martensitic together with different carbide contents and graphite in the form of spheroids/nodules. Some critical grades are heat treated for higher strength. Chemical composition and structure are chosen to suit specific application. Application: Roughing and intermediate rolls for slabbing and blooming mills. Roughing, intermediate and finishing for rail and structural mils. Finishing for wire rod and narrow strip mils. Advantage: Pearlitic nodular rolls have high strength, good thermal properties and resistance to emergencies as well as small hardness gradient of working layer. Bainitic nodular structures provide for better wear resistance at high surface hardness.

2 Standard Chemical Composition: GRADE Hardness C Si Mn Ni Cr Mo S P Cu Pearlitic to 0.4 to 1.5 to 0.1 to to Pearlitic to 1.6 to 0.45 to 1.6 to to to Accicular to 1.5 to 0.5 to 2.5 to to 0.3 to Accicular to 1.4 to 0.5 to 2.5 to to 0.3 to Alloy Steel Base Rolls / Adamite: These Rolls are special hyper-eutectoid steel rolls alloyed with Nickel, Chromium & Molybdenum. The extra Carbon and special alloys give extra wear resistance and strength. These rolls are statically cast and undergo a special high temperature heat treatment process of double annealing followed by tempering cycles to give a micro structure consisting of fine pearlitic matrix with spherodised / broken carbide. Application: These Rolls are suitable for rolling medium and heavy sections. These rolls are also used for roughing stands of strip mill. Advantage: The biggest advantage of these rolls is almost no hardness gradient in the working layer.

3 GRADE Standard Chemical Composition: Hardne ss C% Si% Mn% Ni% Cr% Mo% S% P% ADAMITE / / /0.9 0/ /1.2 / / / / /0.9 0/ /1.2 / / / / /1.00 0/ /1.2 / / (Checker Plate Mill) 0.8/ / / / /1.2 / Double Poured Alloy Indefinite Chill: These Rolls are made of a high alloyed shell iron and a soft grey iron or ductile iron core metal depending on neck strength requirement. The shell material consists of predominantly Bainitic or Martensitic matrix with free carbides with small quantities of fine flake graphite, which imparts excellent wear and abrasion resistance coupled with resistance to fire cracking. These rolls are cast both through centrifugal and static route. Application: Particularly suitable for rolling of Flat Products in Hot Strip Mills, Plate Mills and the first stand of Tinplate Tandem Cold Mills. Suitable for the finishing stands of wire rod mills as well. Can also be used for rolling of non-ferrous alloys.

4 Standard Chemical Composition: GRADE Hardness C Si Mn Ni Cr Mo S P DP to 0.6 to 2.5 to 1 to to 0.03 to to 0.8 to 0.7 to 1 to to 0.03 to 3 to CI 3.1 to 1.6 to 0.5 to SG 3.1 to 1.6 to 0.5 to Indefinite Chill Alloy Cast Iron: These are cast iron based rolls alloyed with Nickel, Chromium and Molybdenum having a matrix of pearlite and carbide with flake graphite. The material has very good thermal properties coupled with property of imparting good surface finish to the product. These rolls are also available in higher hardness range where the matrix is Bainitic instead of Pearlitic. Applications: These rolls are used primarily for Section Rolling and finishing stands of rod mill. Advantage : This variety is generally cheaper than the spheroidal graphite cast iron rolls, the gradual change in hardness associated with the indefinite-chilled structure allows deeper grooving i.e. indefinite chilled rolls are superior in biting performance, indefinite rolls produce excellent results while achieving maximum functional depth, ensure minimum sacrifice of clear chill layer, as the presence of graphite in indefinite chilled rolls offers strong resistance to thermal shock occurring at the time of accident in the rolling operation compared to other types of cast roll

5 Standard Chemical Compositions: GRADE Hardness C Si Mn Ni Cr Mo S P IC to 0.6 to 0.3 to 1.5 to IC to 0.6 to 1.5 to 0.9 to 0.3 to IC to 1.7 to 0.9 to 0.3 to 1 to to Clear Chilled Rolls: The working surface of Clear Chill Rolls shows the white graphite free structure consisting of eutectic carbide and transformed austenite. This gives a hard layer which confers good resistance to wear. The core and necks exhibit a tough grey structure, and the iron of the transition zone is mottled. Applications: These make excellent work 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. Standard Chemical Compositions: GRADE Hardness C Si Mn Ni Cr Mo S P Cu CC 0.5 to 5 to 1.6 to to 0.3 to to to Hollow max