Silicon carbide addition method
1. Silicon carbide is added to cast iron when melting scrap steel. Because silicon carbide melting to form a silicon dioxide film and its obstruction and the need for a higher temperature. Electric furnace with the scrap in the early addition when the size of 1 to 5 mm silicon carbide, can melt decomposition, reduce the oxidation of ferrofluid, increase the graphite core, and continue to improve the metallurgical quality of ferrofluid, when the absorption rate of silicon carbide is generally higher than 90%.
But with the late stages of melting, silicon carbide all dissolved to complete, its role and will be because of the electric furnace silicon dioxide is reduced by carbon, the role of gradual decline, so we add silicon carbide pretreatment before the molten iron out of the furnace to increase the core of the molten iron solidification, improve the quality of molten iron metallurgy. At this time, because silicon carbide in the furnace before or pouring ladle into the pouring ladle and other different timing to join, to be added at the same time with the use of graphitized carbon increase agent the same particle size. For silicon carbide, because its melting decomposition temperature is higher, the particle size requirements are more stringent.
2. Silicon carbide is added before the cast iron melting out of the furnace. If the electric furnace molten iron is clean at one time, the better pretreatment operation is: when the molten iron at 1 420 ~ 1 450 ℃, after adjusting the silicon carbide composition slagging, molten iron ready to heat up the furnace, the liquid surface to add 0.2 ~ 2 mm particle size of silicon carbide, according to the content of silicon carbide content of 0.1% to 0.3% of the weight of the molten iron in the furnace, and then quickly heat up to the required temperature out of the furnace, spheroidization breeding process . At this time, when adding silicon carbide to raise the temperature, you can observe the liquid surface of the iron in the furnace, due to electromagnetic stirring, silicon carbide is squeezed by the iron around the furnace lining, the liquid surface of the bright white metal oxide film is quickly reduced and disappeared. If the furnace at this time to add 0.2 ~ 1 mm particle size silicon carbide pretreatment, the silicon carbide melt decomposition is relatively fast, pretreatment effect is easy to decline.
Xinyuanzhu Group uses a large-capacity induction furnace, the iron is divided into 3 to 6 packs of multiple iron, spheroidization breeding treatment, the iron is transferred to the automatic pouring machine on the molding line breeding casting. Under such conditions, the pretreatment of the molten iron, if you continue to operate as described above, the furnace needs to add silicon carbide pretreatment several times, will certainly affect the composition of the molten iron in the furnace, so after several experimental studies, the pretreatment operation is generally flushed in the pouring package, placed in the bottom of the package directly into the side of the molten iron, using 0.2 ~ 1 mm fine particles of silicon carbide, the amount of flushing into the molten iron based on the composition of silicon carbide or the length of time the molten iron stays in the furnace at high temperature. select 0.1% to 0.3% of the amount of molten iron, the temperature of the molten iron at 1 480 ~ 1 520 ℃, can be completely molten decomposition, play a pretreatment role.
To sum up, the size of silicon carbide added with the scrap in the early stage: about 1-5 mm; the size of silicon carbide pretreated in the furnace, silicon carbide absorption rate of more than 90%: 0.2 ~ 2 mm, silicon carbide absorption rate of more than 90%; the size of silicon carbide flushed into the ladle: 0.2 ~ 1 mm, silicon carbide absorption rate of more than 50% ~ 60%.
Xinyuanzhu Group specializes in the production of Ductile iron castings, Pig iron gray iron casting, Steel casting, Brass Casting, Malleable Iron Casting, and undertakes batch casting processing of castings. Welcome guests to cooperate with pictures or samples.