Spheroidal graphite iron roll also is known as ductile iron roll and is a roll made by spheroidizing the molten iron with magnesium and pouring it into the sand-lined cold type. Due to the spheroidizing treatment, the graphite carbon inside the cast iron is changed from flake to spheroid, which eliminates the phenomenon of graphite tip stress concentration caused by flake graphite, which significantly improves the strength of cast iron, similar to the cast steel roll, but the abrasion resistance is much higher than the cast steel roll. There are three types of nodules of magnesium, cerium, and calcium and magnesium are commonly used. Spheroidal graphite iron roll can be applied in open-rolling mills, roughing mills and rolling mills before finishing rolling on various sections and plates. When the finished roll bears a large load, it is best to use a ductile iron roll with a casting groove, high strength and excellent wear resistance.
Pearlitic Nodular Cast Iron Roll
Pearlitic nodular cast iron roll has a high content of Ni and Mo alloys and the pearlite, basanite and martensite matrixes with excellent performance. It has good strength, high-temperature performance and anti accident performance with small hardness drop on the work layer. The nodular cast iron roll usually is used in large blanking machines, section steel tandem rolling, bar and wire rough rolling, intermediate rolling mill.
For pearlite nodular cast iron, pearlite content in the matrix structure accounted is more than 80% of ductile iron (nodular iron). The ductile iron conforms to Chinese national standards QT600-2, QT700-2 and QT800-2 belong to pearlite nodular cast iron. This type of ductile iron is usually obtained by normalizing treatment, or it can be obtained by adding alloying elements and cooperating with technological measures. The nodular cast iron roll is mainly used to manufacture parts that require high strength, with certain fatigue strength and wear resistance.
Centrifugal Composite Cast Iron Roll
The cast iron roll is produced by a horizontal centrifugal casting process with high-speed steel as the work layer and nodular iron as the core. The material of centrifugal casting iron roll contains plenty of alloying elements such as Mo, Ni, Cr, etc. The high hardened eutectic carbides & second carbides, evenly distributed in tempered martensitic matrix, make the wear and thermal cracking resistance very excellent. Besides, the resistance to surface roughing is also good. In a condition of hot rolling, the contact points between steel strip and the work rolls can form a thin adherent oxide film on the roll surface, which plays a good role in the wear features and the quality of the strip surface. The main application is as a working roll for hot-rolled strip leveling rack and rack of high-speed wire mill.
Thanks to its higher content of Ni and Mo alloys, basanite and martensite matrixes with excellent performance are produced. There are small changes in hardness. It is extremely efficient in toughness, preserving heat split, preserving surface coarse and abrasion-resistant.
Application
working roll for hot-rolled strip leveling rack;
Rack of tandem rolling mill for section, bar, wire rod and narrow strip
Roll ring and roll of stretch reducing mill for seamless steel tube
Work roll of hot-rolled strip tempering rack and medium plate mill rack
Tandem rolling bar and rack of high-speed wire mill
Bainitic Nodular Cast Iron Roll
Bainitic nodular cast iron roll is made of Ni, Mn, CrH, Mo, etc. It has an acicular structure and would be higher strength and better toughness than pearlite iron. Due to the high alloy content and high casting stress, the acicular bainite ductile iron roll can obtain the ideal comprehensive performance by a centrifugal composite casting process. The feature of bainitic nodular cast roll is that it shaped into graphite ball and its performance can be compared with that of alloy indefinite chilled roll. Its intensity is higher than that of indefinite chilled one, so it is usually used for rest energy casting. Based on the analysis of the macro and microstructures of conventional Ni-Mo bainite ductile cast iron rolls used in bar finishing mills, we have found that the main cause of the spalling failure of the roll surface layer is the low bainite mass fraction in the roll structure, Irrational distribution of carbide morphology, and non-round graphite morphology.
On this basis, by optimizing the mass fraction of alloying elements of conventional bainite nodular cast iron composite rolls (nickel, copper, niobium composite alloying), the purpose of optimizing the structure and properties of the rolls is achieved. The structure of the improved roll is finer, and its carbide morphology has been significantly improved; meanwhile, the addition of alloying elements has significantly improved the bainite strength in the material, and its impact toughness, deflection, section shrinkage, and elongation after fracture are significantly improved compared with conventional Ni-Mo ductile iron, so it can significantly extend the service life of rolls and effectively reduce the production cost of steel.
Alloy Ductile Cast Iron Roll
The alloy ductile cast iron roll is made of acicular nodular cast iron mixing with nickel, chromium, molybdenum. It can be used in various blanking rolling mills for section steel, bar, wire rod and narrow strip, roughing mills, work roll for seamless steel tube, intermediate stand and finishing stand for section steel, bar, wire rod and narrow strip and rolling mills before finishing rolling for various sections and plate steels. The finished roll can also be used in the case of a low load. When the finished roll is subjected to a heavy load, it is preferable to use as a nodular cast iron chill roll with high strength and wear resistance.
Application
Alloy spheroidal graphite iron roll has a lot of usage following as:
Blooming roll rack of rolling mills for section steel, bar, wire rod and narrow strip,
Mill rolls for seamless steel tube
Intermediate and finishing roll rack of rolling mill for section steel, bar, wire rod and narrow strip
For more detailed information, please visit the page of TINVO rolling mill rolls.
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