What are the common types of inoculants?

Common inoculants are roughly divided into the following types: ferrosilicon particle inoculant, silicon barium inoculant, flow inoculant, silicon calcium inoculant,

Ferrosilicon particle inoculant

Ferrosilicon granule inoculant can be used not only in the steelmaking industry but also as a commonly used metallurgical material in the cast iron industry. This is mainly because ferrosilicon granules can be used by cast iron manufacturers to replace inoculants and spheroidizing agents. In the cast iron industry, ferrosilicon granules are used The price is much lower than steel, and it is easier to melt. It is a ferroalloy product with strong casting ability. Better quality ferrosilicon particles have uniform particle size and better incubation effect during casting. They can promote the precipitation and spheroidization of graphite and are necessary metallurgical materials for the production of ductile iron. 75 ferrosilicon is widely used and 45 ferrosilicon is extremely used. few.

Features of ferrosilicon inoculant:

It is economically cheap; in terms of structure, it reduces white spots, improves the uniformity of cross-section structure, promotes A-type graphite, increases the number of eutectic groups, and reduces segregation; in terms of performance, it improves strength and toughness.

Adding amount of ferrosilicon granule inoculant:

The usage amount should be determined according to the actual situation, which is closely related to the condition of the original iron and the molten iron after melting, and should be adjusted according to the actual situation. Under normal circumstances, the addition amount for gray cast iron is 0.2~0.5%; for ductile iron, the general addition amount is 0.5~1.1%; for cast iron horizontal continuous casting ductile iron, the general addition amount is 0.8~1.5%.

Silicon barium inoculant:

Silicon barium inoculant is a bulk metallurgical material made by mixing silicon powder and barium powder according to the required proportion and making steel in a high-temperature furnace. It is an additive in the casting process of the foundry. It can promote graphitization and reduce the tendency of whitening. , improve the morphology and distribution of graphite, increase the number of eutectic clusters, and refine the characteristics of the matrix structure. It has good effects in a short time (about 5-8 minutes) after the incubation treatment.

The size of the barium silicon inoculant must be uniform and moderate in size to avoid affecting the inoculation effect. The molten iron after inoculation must be fully stirred before slag removal.

The addition amount of barium silicon inoculant is generally controlled at 0.3%-0.6%. Do not blindly increase the inoculation amount. Excessive inoculation amount will increase the viscosity of the molten iron and the tendency of slag inclusion, keyholes, and shrinkage.

Uses of barium silicon inoculant:

Silicon barium inoculant is mainly used in the inoculation of ductile iron and gray cast iron liquid. Silicon barium inoculant strongly increases the graphitization core, refines the graphite, promotes the formation of A-type graphite in gray iron castings, and improves strength. For ductile iron castings, it can make the graphite in ductile iron fine and round, and improve the spheroidization level. Highly resistant to recession while preventing associated spheroidization recession. The wall thickness is less sensitive and the structure is uniform. It can significantly reduce the whitening tendency, reduce the relative hardness, improve the cutting performance of castings, and is used as an inoculant and spheroidizing agent in the cast iron industry.

0-0.25mm: used for in-mold inoculation (accurate inoculation and higher efficiency)

0.2-1mm: used for inoculation with flow (the control of inoculation amount is more accurate)

1-3mm and 3-8mm are used for incubation in the bag (the incubation time must be controlled at more than 70% of the tapping time)

8-15mm for incubation in furnace

Introduction to Sui Flow Inoculants:

Flow inoculant is also called instant inoculant, which is to break the inoculant into fine particles (0.2mm-0.8mm). Through a feeding equipment, it enters the molten iron with the flow of molten iron during the ladling process to inoculate it. role.

Calcium silicon inoculant:

The graphitization ability of calcium silicon inoculant is 1.5 to 2 times greater than that of 75FeSi inoculant, which significantly increases the number of eutectic clusters.

When using calcium silicon inoculants, you must understand why Ca is added. Ca is an alkaline earth element and is very reactive. Therefore, it can react with gas atoms or non-metallic elements in molten iron, such as O, S, N, C, and H. Generally, these elements themselves inhibit graphite nucleation or change the growth morphology of graphite. Therefore, one of the main functions of Ca is actually that of a cleaning element. In addition, compounds formed with elements such as S not only remove these harmful elements, but also form the crystallization core of graphite and improve the morphology of graphite. It must be emphasized that calcium silicate inoculant contains 2.4% Al, which has the same effect as Al in the previous ferrosilicon inoculant. Therefore, calcium silicate is a very effective and stable inoculant. However, the disadvantages are rapid decline, large amount of slag, light specific gravity, and high pollution. In order to improve these problems, low Ca inoculants have emerged, whose Ca content is generally less than 16% Ca.