High-strength sulfur-oxygen nucleating agent

Abstract

The invention provides a high-strength sulfur-oxygen nucleating agent. The high-strength sulfur-oxygen nucleating agent comprises the following elements in percentages by mass: 70-76% of Si, 0.2-1.0%of Ca, 0.3-0.5% of Ba, 1.5-2.0% of La, 0.5-1.5% of Al, 0.3-0.9% of S, 0.3-0.9% of O, 0.5-1.5% of Sb and the balance of iron. The sulfur-oxygen nucleating agent is prepared from the following raw materials in parts by weight: 2-4 parts of steel scrap, 130-140 parts of silicon iron, 1-1.4 parts of silicon barium, 1-1.8 parts of calcium silicon, 2-4 parts of pure lanthanum, 1.5-2.5 parts of stibonium, 1-2 parts of FeS and 1-1.4 parts of FeO. By the prepared high-strength sulfur-oxygen nucleating agent, the number of graphite nodules in nodular cast iron can be increased obviously, the strength and toughness of the nodular cast iron can be improved, the chilling tendency of the nodular cast iron is relieved obviously, the nodularity, the number of graphite nodules and the number of ferrites ofthe nodular cast iron are increased, shrinkage in a casting process is eliminated, and complicated castings with excellent quality can be formed.

Description

technical field [0001] The invention relates to the field of cast iron, in particular to a high-strength sulfur-oxygen inoculant. Background technique [0002] The inoculant can promote graphitization, reduce the whitening tendency, improve the morphology and distribution of graphite, increase the number of eutectic groups, and refine the matrix structure. In the casting process of ductile iron, the selection of inoculant is particularly important. At present, the most used inoculant is ferrosilicon, which also contains metal elements such as calcium, barium, strontium, manganese and zirconium. The above-mentioned elements that are reactive with sulfur and oxygen are added to combine with sulfur and oxygen in iron. Provides an efficient heterogeneous crystalline core for graphite. However, the effective sulfur and oxygen in molten iron after spheroidization are greatly reduced, so the effect of adding elements in the inoculant is also limited, and the number of effective cr...

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Problems solved by technology

However, the effective sulfur and oxygen in molten iron after spheroidization are greatly reduced, so the effect of adding elements in the inoculant is also limited, and the number of effective crystal nuclei that may be formed after treatment will restrict the effect of inoculation, and ferrosilicon The tensile strength of the castings obtained from the molten iron produced is below 300MPa, which cannot meet the requirements of some machine castings that require high toughness

[0003] In order to enhance the effect of inoculation, a new type of inoculant, Elkem Sulfur Inoculant, has appeared on the market, which contains 70-76% Si, 0.75-1.25% Ca, 1.5-2.0% Ce, 0.75-1.25% Al, trace amounts of S and O, this new type of inoculant can make the microstructure of ductile iron more uniform than that of the ferrosilicon inoculant, the shrinkage tendency is smaller, and the hardness is relatively strong, but The tensile strength of castings inoculated with this new type of inoculant is generally lower than 420MPa, which still cannot meet the requirements of some high-strength and high-toughness castings (such as QT600-10), etc.

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