Inoculant is a necessary additive in producing cast iron. Nodulizer,or named Spheroidizing agent is an additive to produce high performance castings.
1. Selection of nodularizer:
(1) Low-magnesium nodularizing agent is contain magnesium content of 4%, 5%, and 5.5% , and RE is between 1% and 2%. It is mostly used in intermediate frequency furnace smelting and spheroidizing treatment of low-sulfur molten iron. It has the advantages of gentle spheroidization reaction and easy to absorption of spheroidized elements.
(2) Middle magnesium series nodularizing agentis contain magnesium content of 6% and 7% , which is mostly used in cupola, induction duplex melting, or medium frequency furnace melting pearlite type cast nodular iron castings. According to the wall thickness of the casting and the sulfur content of the original molten iron, the appropriate amount of nodulizer is determined.
(3) High magnesium series nodulizer, suitable for cupola smelting, molten iron with sulfur content of 0.06% – 0.09%, the additional amount is between 1.6% – 2.0%.
(4) The low-aluminum nodularizer is used for castings that are prone to subcutaneous stomatal defects, and castings that require aluminum content in molten iron.
(5) The spheroidizing agent produced by pure Ce and La has fewer pure inclusions in molten iron and round graphite balls after spheroidization. The spheroidizing agent produced by yttrium-based heavy rare earth is suitable for large-section castings, delaying spheroidization recession and preventing block graphite. Sb-containing spheroidizer is used for pearlite ductile iron.
(6) The low-silicon nodularizer is suitable for foundries that use a large amount of return material; the nickel-magnesium nodularizer is used for high-nickel austenitic ductile iron.
2. Selection of inoculant:
(1) Si, Ba, Ca, and Al alloys are widely used, with an ideal inoculation effect and less dosage. Barium is a very active element. The low calcium and barium silicon-barium inoculant have strong graphitization ability. It is the first choice for gray cast iron, ductile iron and vermicular graphite cast iron.
(2) High-grade deoxidizing inoculant, which has a strong deoxidizing effect and increases silicon, saves cost and is used to prevent stomata and subcutaneous stomata.
(3) Silicon strontium inoculant does not increase the number of eutectic groups in gray cast iron, but has a good graphitization effect, and has a significant effect on preventing thin-walled and uneven thickness castings from whitening, so it can prevent thin-walled and uneven thickness castings (cylinder block). , cylinder head) leakage.
(4) The high-aluminum and low-calcium ferrosilicon inoculant have a remarkable effect on eliminating the white of gray iron. The bismuth-containing ferrosilicon inoculant makes up for the lack of obvious effect of single addition of bismuth. Silicon-zirconium inoculants can refine austenite dendrites and improve the strength of cast iron. The addition of manganese to the inoculant can reduce the melting point of the multi-component alloy to facilitate diffusion and absorption in the molten iron. The effect of the silicon calcium barium manganese inoculant is particularly prominent in this regard.
(5) Rare earth inoculants have special effects on reducing the brittleness of white cast iron. For high-grade hypoeutectic gray cast iron, the graphite morphology can be significantly improved, and the strength of the cast iron can also be increased without deliberately reducing the carbon content, thereby improving the machinability.
(6) The inoculation block in the mold is a treatment method that saves resources and has a better inoculation effect. The pouring system is equipped with a foam ceramic filter, which constitutes a combination of producing high-quality castings. The inoculation block will be favored by more foundry enterprises.
(7) The specially produced covering agent has a pure composition and uniform particle size, which is more conducive to obtaining stable and high-quality casting products.