Spheriodizing technique for preventing Mg from fireless and floating in nodular cast iron production

Abstract

The invention discloses a spheroidizing process for preventing magnesium burning loss and floating during the production of nodular cast iron. 1. Pass protective gas into the spheroidizing treatment bag and add a spheroidizing agent, and exclude the spheroidizing agent and the spheroidizing treatment bag Second, under the protection of the gas protective film, the spheroidizing agent is heated, and the main spheroidizing element magnesium is in a molten state; third, the molten iron is added to the spheroidizing treatment bag. The protective gas is reducing gas or inert gas, such as carbon dioxide and argon. Pure magnesium can also be used as a spheroidizing agent to directly spheroidize molten iron. The present invention is a kind of nodulizer and molten iron that can prevent the burning of magnesium in the nodulizer during the production of nodular cast iron, can prevent the magnesium from floating on the molten iron, and the magnesium can be quickly and evenly melted in the molten iron without forming localized Enriched area and local poor area, easy to operate, reliable performance, anti-magnesium burning, floating spheroidization process.

Description

technical field [0001] The invention relates to a production process of nodular cast iron, in particular to a spheroidization process for preventing effective element magnesium in a nodularizer from burning and floating during the production process of nodular cast iron. Background technique [0002] Ductile cast iron is a cast iron material with excellent mechanical properties, but in order to obtain ductile cast iron in the molten iron smelting process, a nodularizing agent must be added to the molten iron to spheroidize the graphite in the molten iron. The higher the level of spheroidization, that is, the more the number of spheroidal graphite, the more uniform the size and shape, the better the performance of the nodular cast iron. In production, due to the influence of various factors, there are phenomena such as low spheroidization level of nodular cast iron, uneven spheroidization, instability, and spheroidization decline. The main factors hindering the spheroidizati...

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Problems solved by technology

[0006] However, this process has the following disadvantages: when the molten iron is in contact with the nodulizer, the low melting point metals in the nodulizer, especially magnesium, melt under the action of the high temperature of the molten iron. Part of the magnesium burns, and because the specific gravity of magnesium is lighter than that of iron, part of the magnesium that has not been melted in time floats on the molten iron, and eventually burns out in the air

[0007] In the case of a certain molten iron composition, the amount of nodularizing elements required is also determined, but in this process, the burning loss of nodularizing element magnesium cannot be determined, so in the production process, the removal of oxygen in molten iron 1. The amount of sulfur is uncertain, so the formation of spherical graphite cannot be effectively controlled. Therefore, when the composition of molten iron, temperature, and the amount of spheroidizing agent are the same, the quality of spheroidizing of different batches of molten iron is different.

Since the burning loss of magnesium cannot be determined, the amount of magnesium remaining in molten iron after spheroidization is different. When the amount of residual magnesium is too small, the nodular cast iron is transformed into low-grade gray iron with extremely poor performance, and the spheroidization cannot be guaranteed. Reliability, causing molten iron to be scrapped due to spheroidizing quality and spheroidizing degradation

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