Experimental raw materials mainly include metal raw materials, non-metal raw materials and modeling materials. Metallic materials mainly include cast pig iron, Q235 scrap steel, reheating materials, mengtie, fesimg8re3 alloy and 75 ferrosilicon, while non-metallic raw materials include polystyrene foam board, water-based fire-resistant coating, high-purity carburizer, etc.
Nodular cast iron qt10 is selected as cast pig iron. Its chemical composition is 4.5%c, 0.69%si, 0.19%mn, 0.022%s, 0.037%p, and the residual is Fe.
Q235 scrap steel is selected as the charge, on the one hand, because the carbon content of Q235 steel is low, which has a significant effect on adjusting the carbon content in the ferroalloy; On the other hand, there are few impurity elements in Q235 steel, which is conducive to obtaining high-purity and high-quality molten iron.
The recycled materials are mainly the non-conforming castings produced by the sparing injection system of castings and the unreasonable discharge temperature control. The selected recycled materials are close to the target composition of castings. Adding return charge to the furnace charge can reduce the amount of cast pig iron, reduce the waste of return charge, increase the utilization rate of material and save energy
The ferromanganese selected is 65mnfe, and the carbon silicon content meets the standard requirements of gb3795-96.
The content of main elements of fesimg8re3 spheroidizing agent used in the experiment is 43%si, 8%mg, 3%re. When spheroidizing, the particle size of the spheroidizing agent is 5-25mm.
The inoculant used in the experiment was 75fesi.
The non-metallic raw materials used for smelting are mainly high-purity carburizing agents, whose chemical composition is w (c) >95%, w (s) <0.2%, moisture content <1%, and particle size is 0.5-6mm.
During smelting, the chemical composition of the alloy is determined according to the type of cast iron produced, and the smelting raw materials are proportioned according to the chemical composition of the casting to obtain molten iron with different composition. The smelting equipment is a medium frequency induction furnace.
The non-metallic raw materials used in lost foam casting process also include polystyrene foam board, water-based fire-resistant coating, hot-melt adhesive, etc. The polystyrene foam board used in the experiment is an expandable polystyrene material with a density of about 20mg/cm3.
The water-based refractory coating uses quartz powder as refractory aggregate, starch as binder, bentonite as suspending agent, alkylphenol polyoxyethylene ether as auxiliary agent and water as carrier. The weight ratio of water to refractory coating powder shall be controlled within 1.2-1.5.
The thermosol adopts polyvinyl acetate – ethylene thermosetting adhesive, in which polyvinyl acetate is the base material.
In addition to the above materials, quartz sand without binder is used as molding material in lost foam casting.