1. Selection of nodulizer:

(1) The magnesium content of 4%, 5% and 5.5% belongs to low magnesium nodulizer, and RE is between 1% and 2%. It is mainly used for intermediate frequency furnace smelting and nodulizing treatment of low sulfur molten iron. It has the advantages of mild spheroidizing reaction and easy absorption of spheroidizing elements.

(2) The magnesium content of 6% and 7% belong to medium magnesium series nodulizing agent, which is mainly used for cupola and electric furnace duplex smelting, or medium frequency furnace smelting pearlitic as cast ductile iron castings. According to the casting wall thickness and the sulfur content of the original molten iron, determine the appropriate amount of nodulizing agent, which has a wide scope of application and a wide nodulizing treatment process.

(3) High magnesium series nodulizing agent, suitable for cupola melting, molten iron with sulfur content of 0.06% - 0.09%, with addition amount of 1.6% - 2.0%.

(4) Low aluminum nodulizer is used for castings that are easy to produce subcutaneous porosity defects, and castings that have requirements for aluminum content in molten iron.

(5) The spheroidizing agent produced by pure Ce and pure La has few pure inclusions in molten iron and round graphite spheres after spheroidizing treatment. The nodulizing agent produced by Yttrium based heavy rare earth is suitable for large section castings, which can delay nodulizing decay and prevent massive graphite. Sb containing nodulizer is used for pearlitic ductile iron.

(6) The low silicon nodulizer is suitable for casting plants that use a large amount of recycled materials; Nickel magnesium nodulizer is used for high nickel austenitic ductile iron.

2. Selection of inoculant:

(1) Si, Ba, Ca, Al alloys are widely used, and the inoculation effect is very ideal with a small amount. Barium is a highly active element. It is a low calcium barium silicon barium inoculant with strong graphitization ability. It is the first choice for gray iron, ductile iron and vermicular iron castings.

(2) Advanced deoxygenation inoculant, with strong deoxygenation effect, can increase silicon, save costs, and is used to prevent blowholes and subcutaneous blowholes.

(3) The silicon strontium inoculant does not increase the number of eutectic cells in gray cast iron, but it has a good graphitization effect. It has a remarkable effect on preventing the white mouth of thin wall and uneven thickness castings, so it can prevent the leakage of thin wall and uneven thickness castings (cylinder block and cylinder head).

(4) The inoculant of high aluminum and low calcium ferrosilicon has remarkable effect on eliminating gray iron chill. Bismuth containing ferrosilicon inoculant makes up for the defect that the effect of adding bismuth alone is not obvious. Silicon zirconium inoculant can refine austenite dendrite and improve the strength of cast iron. Adding manganese to the inoculant can reduce the melting point of multi-component alloys and facilitate diffusion and absorption in molten iron. The effect of silicon calcium barium manganese inoculant is particularly prominent in this regard.

(5) Rare earth inoculants have special effect on reducing the brittleness of white cast iron. For high grade hypoeutectic gray cast iron, it can obviously improve the graphite morphology, without deliberately reducing the carbon content, it can also improve the strength of cast iron, thus improving the machinability.

(6) In mold inoculation block is the most resource saving and best inoculation method. The gating 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 casting enterprises.

(7) The specially produced covering agent, with pure composition and uniform particle size, is more conducive to obtaining stable high-quality casting products.