Nodulating agent and inoculant are important materials in nodulating process. In addition to stable quality, the following six factors need to be considered in selecting the appropriate nodulating agent.
If spheroidizing treatment temperature > At 1480℃, the spheroidization reaction will be more intense, resulting in a lower magnesium absorption rate. In order to make the nodulating reaction stable, the nodulating agent with relatively high calcium content can be selected. If the spheroidizing temperature At 1480℃, a spheroidizing agent with a relatively low calcium content can be used.
If the height to diameter ratio of the treatment package is 1:1, the loss of magnesium vapor will lead to a decrease in magnesium absorption, and it is recommended to use a nodulator with a higher calcium content. If the ratio of height to diameter of the treatment package is 2:1, the spheroidization reaction will be relatively smooth, and the magnesium vapor will diffuse into the iron liquid, and the magnesium absorption rate will be improved.
If the coating method is not used, the smoke from the nodularization reaction will enter the atmosphere and produce a harsh white light. In order to make the nodulating reaction stable, low magnesium and high calcium nodulating agent can be used. If the cover method is used, the liquid iron will not splash, and the smoke generated is less, the nodule agent with high magnesium and low calcium can be used to reduce the amount of addition and reduce the cost of nodule.
If the weight of the liquid iron is less than 500kg, then a smaller particle size can be used, and it is recommended to use a particle size of 12mm or less. If the weight of the liquid iron is 500~1000kg, a nodulator with a larger particle size can be used, such as a nodulator with a particle size of 3~25mm. If the weight of the liquid iron is greater than 1000kg, a spheroidizing agent of 4~32mm can be used.
If the process yield of the casting product is low or the scrap rate is high, you want to melt it by adding more return charges and scrap steel, and the casting has strict requirements for the silicon content of hot metal. Under the premise that the inoculation amount can not be further reduced, low silicon spheroidizing agent can be used for treatment, which can increase the return charge by 8% to 15%, which can reduce the production cost of the foundry.
If the sulfur content of the original iron liquid is high, if no desulfurization treatment is carried out, the nodulator with high magnesium and high rare earth is needed, and the amount of addition will be higher, if the sulfur content of the original iron liquid is low, the nodulator with low magnesium and low rare earth can be used, and the amount of addition will be low, and the cost of the nodulator with low magnesium and low rare earth will be cheaper.
The inoculant is mainly to promote graphitization, reduce the white tendency, improve the shape and distribution of graphite, increase the number of eutectic clusters, and refine the matrix structure, while the spheroidizing agent can promote the crystallization of graphite into a sphere in the ball ground cast iron.
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