Inoculation treatment is an indispensable link in the production of ductile iron. Its purpose is to increase the number of graphite nodules, improve their roundness, refine graphite nodules, prevent spheroidization recession, reduce the tendency of white mouth, and prevent the formation of graphite nodules between eutectic clusters. Free cementite, etc.
The inoculant commonly used in the production of ductile iron is 75 ferrosilicon, but its inoculation effect is poor. In order to eliminate free cementite, a large amount needs to be added. However, in order to control the final silicon content, the silicon content of the original molten iron must be reduced. This brings certain difficulties to the utilization of recycled materials.
Advantages of silicon barium inoculant compared with ferrosilicon inoculant:
Strong anti-recession ability, the anti-recession time is twice that of 75Si, and its added amount is less than half of that of 75 ferrosilicon inoculant, and at the same time prevents the associated spheroidization and recession.
Reasonable control of the amount of silicon-barium inoculant can effectively improve the graphite shape of ductile iron. In order to ensure the inoculation effect, the amount of silicon-barium inoculant should be controlled at 0.3%~0.5%;
Content: Si: 68%-72%, Ba: 2%-5%, Ca: about 1.5%
For: Ductile Iron
0-0.25mm: used for inoculation in the mold (precise inoculation, higher efficiency)
0.2-1mm: used for inoculation with flow (the control of inoculation amount is more accurate)
1-3mm, 3-8mm are used for inoculation in the bag (the inoculation time must be controlled at more than 70% of the tapping time)
8-15mm for inoculation in furnace
The lumpiness of the inoculant should ensure uniform particle size and moderate size, so as not to affect the inoculation effect, and the molten iron after inoculation should be fully stirred before slag removal.
The amount of inoculant added is generally controlled at 0.3%-0.6%. Do not increase the amount of inoculant blindly. Excessively high inoculant amount will increase the viscosity of molten iron and the tendency of slag inclusion, keyhole, and shrinkage porosity.
Silicon-barium inoculant is a kind of inoculant that can promote graphitization, reduce the tendency of white mouth, improve the shape and distribution of graphite, increase the number of eutectic groups, and refine the matrix structure. ) has a good effect, and the silicon-barium inoculant is mainly suitable for general or post-instantaneous inoculation in various situations.
Silicon barium inoculants are mainly used in the inoculation of nodular cast iron and gray cast iron molten iron. The silicon-barium inoculant strongly increases the graphitization core, refines the graphite, promotes the A-type graphite in the gray iron casting, and improves the strength. For the ductile iron casting, it can make the graphite in the ductile iron fine and round, and improve the nodularization level. Resistant to fading while preventing the associated nodular fading. The wall thickness sensitivity is small and the tissue is uniform. Significantly reduce the whitening tendency, reduce the relative hardness, improve the machinability of castings, and be used as inoculants and nodularizers in the cast iron industry.