High rare earth low magnesium ferrosilicon alloy QB/T003-2004 Grade chemical composition% RE Mg Ca Si Ai Fe FeSiMg4Ca2RE8 7-9 3.5-4.5 1.5-2.5 ≤44 <> Balance FeSiMg5Ca2RE10 9-11 4.5-5.5 1.5-2.5
Creeping agent and compacted graphite iron
Rare earth ferrosilicon alloy (creeping agent)
The graphite of gray cast iron has a sheet-like structure, and its mechanical properties are in accordance with JB/T4406-1999 standard, a total of 5 grades, tensile strength σb260 ~ 420Mpa, elongation from δ-22%. The tensile strength of nodular cast iron is σb350-900Mpa, and the elongation is δ-22%. However, the mechanical properties of some engineering materials require the use of gray iron castings to meet the requirements, and the use of ductile iron castings is too high; for this reason, a material between gray iron and ductile iron is called vermicular graphite cast iron. The compacted graphite cast iron has unique structural properties.
The graphite shape of vermicular graphite iron is between sheet and spheroidal graphite. Its strength and toughness are higher than that of gray cast iron. Its thermal conductivity, vibration absorption and casting processability are better than that of ductile iron, replacing high-strength gray cast iron. Alloy cast iron black core malleable cast iron and low elongation grade ductile iron.
Generally, the graphite in the molten iron exists in the form of flakes and layers. When the ferrite is added to the molten iron, the graphite becomes worm-like, and its graphite form is between the flake and the spheroidal graphite cast iron, and the mechanical properties of the mechanical material are high. Gray cast iron, lower than ductile iron. This alloy that treats the molten iron is called a creeping agent, and the treated cast iron is called a vermicular cast iron.
Vermicular graphite iron is mainly used in high-power diesel engine cylinder heads, motor casings, machine bases, drive box housings, brake drums, cast iron molds, steel ingot molds, valve bodies, refrigeration machinery, textile machinery, etc. China's engineering and technical personnel use the carrier rocket nozzle produced by vermicular graphite cast iron to instantly resist the high temperature of 3000 °C.
The production of vermicular graphite cast iron is still an indispensable process. The purpose of the inoculation treatment is to prevent the white mouth of the casting and increase the number of eutectic groups. Refine the graphite, improve the mechanical properties of the material and inhibit the decay of the creep.
The production method of compacted graphite iron is basically the same as that of ductile iron.
The amount of creeping agent added depends mainly on the S content and CE of the original molten iron. The production of vermicular cast iron, the amount of S in the molten iron is 0.03%-0.06%, the content of CE is 4.3%-4.7%, and the Mg residue in the vermiculite is 0.03%. When -0.06%, RE residual 0.04% -0.07%, the amount of the creeping agent added is 1.0% - 1.8%, and the performance indexes required for the vermicular graphite iron castings are obtained.
The creeping agent uses the same particle size as the spheroidizing agent and is determined according to the capacity ratio of the ladle.
Metallographic structure and mechanical properties of vermicular graphite iron JB/T4403-1999
Pearlite + ferrite
Ferrite + pearlite
High rare earth low magnesium ferrosilicon alloy QB/T003-2004
Description: This product is a conventionally used creeping agent. It can be selected according to the amount of S in the production of cast iron original molten iron in the region. Various components can also be adjusted according to user requirements to meet the needs of users to produce vermicular graphite iron castings.