inoculant in casting

Inoculants are ferroalloys that have a good inoculant effect in casting. It can effectively increase the number of eutectic pellets in the molten iron and promote good reactions between the elements. Since the inoculants have an important role in casting, then in the casting process The correct use of inoculant can not only save the amount of inoculant used, but also ensure the effect of inoculation. It is important to use the inoculant in casting correctly.

First, the particle size of the inoculant should not be too coarse or too fine. If the particle size is too coarse, it cannot be melted and absorbed by the molten iron more quickly, and the residual undissolved inoculant particles mixed into the casting will deteriorate the performance or cause scrap. The particle size should not be too fine. The powdered inoculant is easily oxidized and burned, loses inoculation, and will cause slag inclusion in the casting. For the inoculant, the infusion method is used to process the molten iron of less than 0.5T. When the temperature of the inoculant is 1390 to 1450 ° C, the particle size of the inoculant is preferably 1 to 3㎜. When the amount of molten iron is more than 0.5T and less than 2T, and the temperature of the molten iron is 1390 to 1450 ° C, the particle size of the inoculant is preferably 3 to 8㎜. In addition, if the amount of molten iron is low or the temperature is low or the instant inoculation method is used, the particle size is preferably 0.2 to 1 ~.
Second, the inoculant should not be added rashly, we must pay attention to methods. If the inoculant floats on the surface of the metal liquid, it will oxidize quickly and be difficult to be absorbed by the metal liquid. Therefore, when the punch method is adopted, it should be accurately added to the contact point of the molten iron flow with the liquid surface or the contact with the pouring tank. As the inoculation method has a direct impact on the inoculation effect, it can also adopt the gating cup incubation, silicon iron rod incubation, bulk floating silicon inoculation, inoculation silk inoculation, iron flow inoculation, and in-type inoculation.
Third, It is forbidden to use pure silicon or pure ferrosilicon as inoculant. Pure silicon or ferrosilicon without calcium, strontium, barium, and aluminum cannot be used as inoculants, because graphite relies on the heterogeneous nucleation of silica precipitated in the molten iron, while silica relies on the sulfur oxidation of calcium, strontium, barium, and barium. Heterogeneous nucleation can prevent the supercooling and white mouth tendency of the molten iron. Should use at least Ca, Al, Ba, Re and other elements, containing silicon iron greater than 70% as inoculant, or use silicon-zirconium-based, silicon-calcium-based, silicon-cerium-based, silicon-barium-based, etc. Inoculant.
Fourth, It is forbidden to use damp inoculants. When wet inoculants are added to the metal liquid, the water and metal elements in the metal liquid react at high temperature to generate metal oxides and hydrogen. The generated primary hydrogen is dissolved in the metal liquid. Causes defects such as subcutaneous pores in the casting. Therefore, the inoculant must be dry before use.
Because the inoculant is especially important in the casting process, as a casting worker, it is more important to use the inoculant correctly to ensure the quality of the process. Through the above four methods of using the inoculant correctly, the effect of the inoculant can be achieved in casting. Status, I hope everyone pays more attention!
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