selection of inoculants
In the selection of inoculants, the following items should be noted:
1. Reduce the depth of white mouth. RE and Ca series inoculants are used for low-sulfur molten iron; carbon-based or graphite is used for high-sulfur molten iron.
2. Reduce the depth of white mouth and improve the tensile strength. Graphitization and stabilization (containing pearlite stabilizing elements) compound inoculant are used. When using graphitized inoculants, RE, Ca and Ba are better.
3. Improve the tensile strength. Stabilized inoculants are used, followed by nitrogen series and rare earth series.
4. Reduce section sensitivity. Use stabilizing and Ba inoculants.
5. Electric furnace smelting molten iron. Increase the amount of inoculants or use rare earth inoculants;
6. Use rusty furnace charge or molten iron to oxidize (the molten iron is not allowed to be severely oxidized). Use inoculants with strong deoxygenation ability (such as RE, Mg) to increase the amount of inoculation.
7. The composition of molten iron. High-grade molten iron needs to use more inoculants, and low sulfur content in molten iron needs to increase the inoculant dosage (especially S<0.05%), or use rare earth inoculants.
8. Large parts, thick parts and obvious decline. Use "long-acting" inoculants, such as Ba, Zr, Sr series, and use high-melting, large inoculants.
9. Thin-walled parts. Inoculant with strong anti-white mouth ability, and increase the dosage appropriately.
10. Molding conditions. High-pressure molding, chrome ore sand molds and other fast heat transfer molds require more inoculants.
11. The tapping temperature and pouring temperature. Use an inoculant with a high melting point and slow decline at high temperature.
12. Pouring method. Large ladle pouring, air pressure ladle pouring, and mechanized automatic pouring should use slow-decay inoculants and increase the dosage.
13. Breeding method. For inoculation in the iron trough, inoculation in the bag, the amount of inoculant is large, after inoculation, iron flow inoculation, and inoculation in the mold, the amount of inoculant can be less, the melting point should be low, and the particle size should be small. FeSi75 is better.