Adding rare earth elements to gray cast iron to improve its properties

Adding rare earth elements into gray cast iron can significantly improve the mechanical properties of gray cast iron, such as hardness, tensile strength and wear resistance; At the same time, it can also reduce the Adding rare earth elements into gray cast iron can significantly improve the mechanical properties of gray cast iron, such as hardness, tensile strength, wear resistance and so on; At the same time, it can also reduce the white tendency of gray cast iron, purify the molten iron and remove impurities. Inoculation treatment is one of the important means to improve the properties of cast iron. Inoculation treatment has been applied to cast iron for many years. With the increasing requirements for cast iron materials, inoculation technology and inoculation mechanism are also deepening. The manufacturing method of inoculating low-carbon equivalent gray cast iron is to add inoculants such as guitie during flame refining for inoculation treatment, because the content of carbon and EVA in the molten iron before inoculation treatment is very low. If it is wound into the mold without inoculation treatment, intergranular graphite or pitting, white cast iron and other structures will appear in the cast iron, For this low carbon equivalent molten iron, a small amount of inoculant is added in front of the furnace, and the inoculant is dissolved into the molten iron to promote the formation of graphite core and improve the graphitization ability of molten iron. In this way, the graphite obtained in cast iron is more and fine, bent and evenly distributed, and the matrix is basically fine pearlite, The cast iron obtained by inoculation treatment of this low-carbon and low-carbon molten iron is called inoculated cast iron. Inoculation treatment has become an indispensable means to produce gray iron castings. Although the research and production of gray iron castings in China are deepening day by day, there is still a large gap with foreign countries. It is mainly reflected in:

  1. The section uniformity of gray cast iron is poor. The pearlescent volume at the thick wall is only 50% – 80%, and the hardness is only 130hb-150hb. The hardness difference at the section exceeds 50hb, and the matrix strength is lower than 150MPa.
  2. Large section sensitivity and poor processing performance.
  3. Poor material stability and low process yield.
  4. Gray cast iron has thick wall and heavy weight.

Due to the relatively backward inoculation and modification technology and melting technology in China, the strength of gray cast iron produced is often lower than that of foreign gray cast iron with the same chemical composition. Even if the strength meets the requirements, the stability of gray cast iron is very poor, and the scrap rate is high, which makes the production cost of domestic gray cast iron very high, Some products can only rely on imports.

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