Method for casting nodular cast iron with large section

Abstract

The invention discloses a method for casting nodular cast iron with a large section. The carbon content and the number of graphite pebbles per unit area are increased, so that the problem of fragmented graphite can be solved; the ideal carbon content is 4.1 to 4.3 percent; the silicon content is 2.0 to 2.2 percent; instantaneous inoculation is added on the basis of the original inoculation, namely during pouring, pouring cup inoculation is performed by using 1 percent of No.75 silicon powder with the granularity of between 0.3 and 1mm; generally, common rare-earth-magnesium-silicon-iron alloy is used as nodulizer and has a wide application range, but during production of the nodular cast iron with the large section, decaying spheroidisation resistance and distortion-invariant capacity of the graphite are low; and in order to overcome the disadvantages, the improved scheme of D-2 heavy rare earth nodulizer is adopted, and during spheroidization, the common rare-earth-magnesium-silicon-iron alloy accounts for 60 percent and the D-2 heavy rare earth nodulizer accounts for 40 percent based on the total weight of the nodular cast iron. The method has the advantages that: the problems of graphite distortion, a small number of spheroidal graphite and fragmented graphite are solved, so that the spheroidization of the central position of a casting is improved and the requirement of a template of an injection molding machine can be fully met.

Description

technical field [0001] The invention relates to a casting method of large-section ductile iron, and the specific technical field belongs to the casting technology of producing injection molding machine templates from ductile iron. Background technique [0002] Injection molding machines are widely used in the industrial field. Many metal and plastic molding require injection molding machines, so the working intensity of injection molding machines is relatively high. The template thickness used by many injection molding machine manufacturers is greater than 100mm. Generally, ductile iron castings with a wall thickness greater than 100mm are called large-section ductile iron. Due to the thick cross-section and slow cooling rate, graphite distortion often occurs in the center of the casting or at the hot joint, the number of nodular graphite is reduced, and the structure is coarse. Especially, it is easy to produce fragmented graphite, which reduces the mechanical properties of...

AI Technical Summary

Problems solved by technology

It has a wide range of applications, but for the production of large-section ductile iron, it often has poor resistance to spheroidization recession and graphite distortion.