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Niobium has been widely used in metallurgical rolls. At present, the main problem encountered by domestic roll manufacturers in using niobium to produce rolls is the cost problem. As Nb can significantly improve the strength, hardness, wear resistance and high temperature structure stability of chilled cast iron, the production of Nb-containing rolls will be further expanded in the future.
The domestic wear-resistant material market is very large, and the wear-resistant cast iron with good reputation should be bainite ductile iron. There are two main methods to produce bainite ductile iron. One is to heat the ductile iron to change its structure into bainite. The other is to directly form bainite structure during solidification by adding 3%-4% Ni. The former does not contain alloying elements, but the cost of heat treatment equipment and heat treatment should be increased. The latter eliminates the trouble of heat treatment, but the large amount of nickel additions increase the cost of alloys. Because niobium has obvious effect on bainite transformation of FERROCARBON alloy, the production of bainite ductile iron by substituting a small amount of niobium for nickel may become the next hot topic in the research of bainite ductile iron.
At present, the problem that is difficult to solve in cast iron materials is the wear-resisting and corrosion-resisting materials working at high temperature, that is, so-called high temperature wear-resisting cast iron and corrosion-resisting cast iron. In metallurgical and chemical industries, the demand for these special cast iron is very urgent. Because niobium can remarkably improve the high temperature structure stability of cast iron, its application in these special cast iron is expected to have broad prospects.
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