Inoculation method of nodular cast iron

Abstract

The invention discloses an inoculation method of nodular cast iron, relates to a preparation method of nodular cast iron alloy, and belongs to the technical field of nodular cast iron alloy production. The inoculation method comprises the steps of in-ladle inoculation, ladle-to-ladle inoculation and metal-stream inoculation. The inoculation method has the beneficial effects that the ladle-to-ladle inoculation process is added between the in-ladle inoculation step and the metal-stream inoculation step, an instantaneous multi-inoculation special technology is realized, the long-acting inoculation of molten iron is achieved, the residual magnesium content in nodulizing molten iron can be effectively reduced, the number of cementite in a casting-state structure is reduced, as for the mechanical performances of the nodular cast iron, the tensile strength of the nodular cast iron can reach 453 Mpa, the yield strength of the nodular cast iron can reach 287 Mpa, the ductility of the nodular cast iron can reach 21-25%, and the number of graphite nodules in the nodular cast iron reaches 150 / mm<2>.

Description

technical field [0001] The invention relates to a method for preparing a nodular cast iron alloy, which belongs to the technical field of nodular cast iron production, in particular to a nodular cast iron inoculation method. Background technique [0002] Ductile cast iron is spheroidized graphite obtained through spheroidization and inoculation treatment, which effectively improves the mechanical properties of cast iron, especially improves plasticity and toughness, thereby obtaining higher strength than carbon steel. Ductile cast iron is a high-strength cast iron material developed in the 1950s. Its comprehensive performance is close to that of steel. It is based on its excellent performance that it has been successfully used to cast some complex stress, strength, toughness, and wear resistance. Parts with high performance requirements. Spheroidization refers to the process in which graphite in cast iron becomes graphite crystallization under the influence of added nodular...

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Problems solved by technology

[0005] The ductile iron castings produced by conventional technology can meet the product requirements after testing, but the number of graphite balls can only reach about 50-70% of the standard requirements, so that it cannot meet the preparation requirements of special castings. For example: large castings due to size It is too large, limited by the capacity of the heat treatment furnace, it can only be produced in the cast state, and the wall thickness is generally more than 100mm. Graphite distortion occurs, the number of balls decreases, graphite balls increase, grains become coarser, the spheroidization rate decreases, component segregation, intergranular carbides increase, and graphite floats, resulting in spheroidization recession and greatly reducing the mechanical properties of castings

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