Nucleating agent used for improving graphite form in gray pig iron and preparing process thereof

Abstract

The invention provides a nucleating agent used for improving graphite form in gray pig iron and a preparing process thereof. The nucleating agent comprises the following raw materials including silicon iron, rare earth ferrosilicon, silicon-calcium-barium and silicozirconium. The raw material of the nucleating agent comprises, by weight percent, 60 to 68% of silicon iron, 15 to 21% of rare earth ferrosilicon, 8 to 13% of silicon-calcium-barium and 3 to 6% of silicozirconium. Through composite of particular elements of barium, calcium, zirconium and the like added in the casting process, the crystallization way during graphite precipitation in the gray pig iron solidifying process can be changed, the compound, formed in molten iron, by the nucleating agent suspends in the molten iron as nonmetallic inclusions, a large amount of outside cores are provided for graphite for promoting graphitization, the number of primary graphite and eutectic graphite crystal nucleuses in the molten iron can be increased, the graphite precipitation is improved, meanwhile, the graphite precipitated form is improved, the tip end of the flake graphite can be passivated, the mechanical property is improved, the casting section sensibility is reduced, and the casting strength and toughness use properties can be improved.

Description

technical field [0001] The invention relates to an inoculant for cast iron, in particular to an inoculant for improving the morphology of graphite in gray cast iron and a preparation process thereof. Background technique [0002] The carbon content of gray cast iron is relatively high (2.7% to 4.0%). The carbon mainly exists in the form of flake graphite, and the fracture is gray. Due to the existence of flake graphite, it has good wear resistance. The flake graphite in gray cast iron is long and thin, with a flat surface and sharp ends. When under load, the sharp parts are likely to cause stress concentration, which becomes the starting point of gray cast iron failure, resulting in a decrease in the strength and toughness of the casting. The current problem is: the common inoculant in production is ferrosilicon, and the above-mentioned reactive elements are added to combine with sulfur and oxygen in iron to provide effective heterogeneous crystallization cores for graphite....

AI Technical Summary

Problems solved by technology

The flake graphite in gray cast iron is long and thin, with a flat surface and sharp ends. When under load, the sharp parts are likely to cause stress concentration, which becomes the starting point of gray cast iron failure, resulting in a decrease in the strength and toughness of the casting.

The current problem is: the common inoculant in production is ferrosilicon, and the above-mentioned reactive elements are added to combine with sulfur and oxygen in iron to provide effective heterogeneous crystallization cores for graphite. However, The sulfur and oxygen content that can work in molten iron is limited, and the number of effective crystal nuclei that can be formed will restrict the effect of inoculation

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