Inoculant and its preparation method and application in ductile iron

Abstract

The invention discloses efficient inoculant, a preparation method thereof and application of the efficient inoculant in nodular cast iron. The efficient inoculant is prepared from, by weight, 58-72% of Si, 0.8-3.2% of Zr, 1.2-2.5% of Nb, 2.8-5.5% of Ca, 1.85-3.58% of Ba, 0.015 or below of Mg, 0.2% or below of Al, 0.26% or below of Mn, 0.02% of below of S, 0.05% or below of P and the balance Fe. By means of the efficient inoculant, the inoculation effect is good, the number and density of spherulitic graphite are increased, graphite nucleation can be effectively promoted, chilling tendency is reduced, the spherulitic graphite size is reduced, the ingredient uniformity of inoculated cast iron is good, the melting point, intensity and performance are greatly improved, and the elongation and impact toughness of ferrite are improved.

Description

technical field [0001] The invention relates to the technical field of nodular cast iron inoculants, in particular to an inoculant, a preparation method thereof and an application in nodular cast iron. Background technique [0002] Ductile iron is an important engineering material. Because the mechanical properties of ductile iron are close to those of steel, many steel castings and forgings are replaced by ductile iron. Therefore, ductile iron has been widely used in industry. In order to achieve good mechanical properties, the following methods can be used: heat treatment, alloying, and inoculation treatment. Among them, inoculation treatment is a relatively simple, economical and effective method. It not only promotes graphitization, prevents free cementite and white pits from appearing, but also helps spheroidization, making graphite smaller and more rounded. The distribution is more uniform, thereby improving the comprehensive mechanical properties of ductile iron part...

AI Technical Summary

Problems solved by technology

[0003] There are two types of inoculants for cast iron: carbon-based and silicon-based. Carbon-based inoculants have the advantages of strong graphitization ability and slow decay, but their melting point is high, and they have to be processed above 1450 ° C. It is difficult to use them in production. Therefore, at present, they are mainly Ferrosilicon is used as the basic inoculant. 75SiFe is commonly used in production, but its inoculation effect is poor. In order to eliminate free cementite, a large amount needs to be added. In order to control the final silicon content, the silicon content of the original molten iron must be reduced. This brings certain difficulties to the application and batching of recycled materials, which seriously restricts the utilization rate of recycled materials in the production process, resulting in a large backlog of recycled materials, which causes a lot of waste in industrial production; in addition, the inoculation of 75SiFe The decay speed is fast, and the thick and large parts or the thick parts of the same casting are prone to thick and distorted graphite balls due to slow cooling rate and long solidification time, and even form vermicular graphite or fragmented graphite, thereby significantly reducing the mechanical properties