Brief introduction of vermicular process for casting of pipe fittings of Ma Steel

Introduction of vermicular process used in casting Ma steel pipe fittings. The shape requirement and tapping temperature of the treated ladle are the same as that of nodular cast iron. However, for the use of magnesium free vermicularizing agent, when using the in pack charging method, some flux and initiator must be added at the bottom of the ladle at the same time to strengthen the boiling effect. Otherwise, it is easy to stick to the bottom of the package, resulting in the Vermicular Agent not fully absorbed and the vermicular treatment failed. Some domestic manufacturers have successfully used Na3AlF6 as detonator in the production of pressure vessels for Ma steel pipe fittings. The amount of ice crystal powder added accounts for about 0.15% of the hot metal re generation to be treated. The in mold creep is transformed according to the in mold spheroidizing process. It has been reported that the in mold creep process has been applied to production in foreign countries, but the in mold creep is still in the experimental research stage in China. It has been proved that the absorption rate of vermicularizing agent can be stabilized and the production of Ma steel pipe fittings can be stabilized by using the in mold creep process. Therefore, it will gradually show its superiority in the production of a large number of single products. The key to the success of the application of in mold creep process is to master the dissolution rate of alloy in the casting process, and to match the absorption of Vermicular Agent by molten iron during creep. The dissolution rate of the alloy is different due to the different types of vermicularizing agents. The dissolution rate of the alloy can be adjusted by changing the size of reaction chamber, pouring temperature and pouring speed. Maanshan Iron and steel can also be obtained by diluting molten iron of nodular cast iron, that is, to dilute the nodularized molten iron with untreated molten iron to obtain Maanshan Iron and steel. The mixing ratio of spheroidized hot metal and original molten iron varies from (6 / 4) - (3 / 7) according to the state of molten iron, residual magnesium, rare earth design and casting wall thickness.