The modification effect of gray cast iron is affected by many factors, such as type, composition, size and oxidation degree of modifier, temperature, addition method and composition of molten iron. The most reasonable adding method of gray cast iron modifier should make the modifier evenly dispersed in the molten iron and pour at the fastest speed. The commonly used modification treatment method in production is to add the modifier to the iron tapping tank of the melting furnace and make it enter the ladle with the molten iron. The particle size of the modifier of the experimental gray cast iron is controlled at 1.5-2.5mm. The modifier should be dried before use, and the modifier should be added by flow inoculation. After stirring and slag raking, it can be poured.
This method is simple and easy, but the oxidation loss of gray cast iron modifier is large (the loss rate is 20% – 30%). If the gray cast iron modifier stays in molten iron for a long time, it is easy to deteriorate and decline, which reduces the modification effect of gray cast iron. Rapid pouring can effectively solve this problem.
| Ingredients | Re | Si | Mn | Ca | Ti |
| FeSiRe27 | 27.5 | 40.06 | <4.0 | <5 | <3.5 |
In the experiment, rare earth ferrosilicon alloy is used as the modifier of gray cast iron (see Table 1 for the main components of rare earth ferrosilicon). The addition method of gray cast iron modifier adopts follow-up pouring, that is, the rare earth ferrosilicon alloy is evenly added during electric furnace tapping, and the rare earth ferrosilicon alloy enters the ladle together with the molten iron, and is poured as soon as possible after slag removal.
| Furnace number | 1 | 2 | 3 | 4 | 5 |
| Rare earth addition (%) | 0 | 0.10 | 0.20 | 0.25 | 0.30 |
The addition amount of rare earth ferrosilicon alloy modifier for gray cast iron is shown in Table 2.