The nodular agent is to add some metal or alloy in the molten iron to obtain spherical graphite cast iron. In China, rare earth magnesium nodular ferrosilicon is widely used. In addition to ferrosilicon rare earth magnesium spheroidizing agent we also commonly have pressure block spheroidizing agent, core-lined spheroidizing agent, powder spheroidizing agent.
(1) compressed nodular spheroidizing agent
The spheroidizing agent contains very low silicon content and is usually called low silicon pressure nodulizing agent. It provides a large margin for subsequent inoculation and is conducive to the production of as-cast ductile iron. However, the alloy is easy to float, the treatment effect fluctuates greatly, and it is better to follow the nodulizing agent when treating. Mixed use.
(2) cored wire nodular agent
Magnesium powder and iron powder coated in thin steel plate or steel plate can be quickly sent into molten iron to achieve spheroidizing. This kind of spheroidizing agent is more expensive and equipment investment is large, but the alloy absorption rate is high, so the total cost of treating ductile iron is almost no increase.
(3) powdered nodular agent
This kind of spheroidizing agent is a patent of Russia. When it is used, magnesium powder and inhibitor are mixed into the ladle, and molten iron flows through the alloy surface, and the spheroidizing effect is reflected layer by layer with the alloy. This special process is called MC.