A Melting Process for Reducing Shrinkage and Porosity in Ductile Iron

Abstract

A smelting process for reducing shrinkage and porosity inside ductile iron, the steps of which are: (1) raw material preparation, preparation of returned material, scrap steel, recarburizer and ferrosilicomanganese; Steel scrap is added to the medium-frequency induction furnace with molten iron residual soup, and the scrap steel is added in three batches, and each batch of scrap steel is added together with a recarburizer; (3) The three batches of scrap steel and recarburizer are all melted and then added back to the furnace for melting. When the molten iron reaches the full furnace and the temperature rises to 1400-1450°C, take samples to confirm the chemical composition (4) After the chemical composition is confirmed, carry out spheroidization treatment, and then pour the molten iron into the pouring machine, and keep the pouring temperature at 1360-1410°C during pouring. The present invention reduces the internal shrinkage porosity of nodular cast iron with a new melting process, increases the number of graphite balls, reduces internal shrinkage porosity, further improves the strength and toughness of the nodular cast iron, can expand the nodular cast iron to the direction of light weight, and reduces production costs ,Energy conservation.

Description

technical field [0001] The invention relates to the field of smelting technology, in particular to a smelting process for reducing internal shrinkage of ductile iron. Background technique [0002] Due to its high strength and high toughness, ductile iron is widely used in various industries, such as automobiles, municipalities, machine tools, ships, railways and locomotives. There are fewer graphite balls in ductile iron, and the smaller the number of graphite balls, the smaller the expansion volume of graphite, which cannot offset the volume change of the part of the volume that decreases when the molten iron changes from liquid to solid, resulting in internal shrinkage in ductile iron, and the quality of cast iron severely affected. SUMMARY OF THE INVENTION [0003] In order to solve the above problems, the present invention provides a smelting process which can increase the number of graphite balls in the ductile iron and reduce the internal shrinkage of the ductile ir...

AI Technical Summary

Problems solved by technology

[0002] Ductile iron is widely used in various industries due to its high strength and toughness, such as automobiles, municipal administration, machine tools, ships, railways and locomotives. The characteristics of high strength and high toughness of ductile iron are closely related to its microstructure, especially the number of graphite balls. The number of graphite balls in ductile iron is small, and the expansion volume of graphite is small when the number of graphite balls is small, which cannot offset the volume change of the part of the volume reduction when the molten iron changes from liquid to solid, resulting in internal shrinkage in ductile iron, and the quality of cast iron severely affected