Special vermiculizer for non-magnetic vermicular graphite cast iron, and preparation technology thereof

Abstract

The invention relates to a special vermiculizer for non-magnetic vermicular graphite cast iron, and a preparation technology thereof, which belong to the technical field of non-magnetic vermicular graphite cast iron production. By weight percent, the vermiculizer comprises the following constituents: 75-85% of rare earth magnesium alloy, 12-20% of high-purity graphite powder and 3-5% of sodium silicate binder, wherein the rare earth magnesium alloy comprises 4-5% of Mg, 1.0-1.5% of Re, 1-1.5% of Al, at most 40% of Si and the rest of Fe. The vermiculizer integrates vermicularizing treatment and inoculation treatment together, and by adopting a graphite moderation technology, seepage velocity of molten iron to the vermiculizer is reduced, a layer-by-layer reaction state is formed, vermicularizing reaction speed and time can be controlled effectively, and alloy absorption rate is improved; by adopting the graphite inoculation technology, an inoculation fade phenomenon is avoided under the efficient inoculation effect of the graphite forming a lot of non-spontaneous crystal nucleus, and non-magnetic vermicular graphite cast iron material with the vermicularizing rate of more than 80% can be obtained steadily.

Description

technical field [0001] The invention relates to the technical field of cast iron vermicularization, in particular to a special vermicularization agent for non-magnetic vermicular graphite cast iron and a preparation process. Background technique [0002] Non-magnetic vermicular graphite cast iron has good machinability performance, high thermal stability and oxidation resistance, and ultra-low magnetic permeability, which expands the application range of non-magnetic cast iron and provides precision for military and industrial non-magnetic parts. Manufacturing provides a new inexpensive high-quality non-magnetic material. The most important modifier in the production of non-magnetic vermicular graphite cast iron is the vermicular agent. In a certain sense, the technical performance of the vermicular agent largely determines the production technology level of non-magnetic vermicular graphite cast iron. [0003] At present, in the production of ordinary vermicular graphite c...

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Problems solved by technology

Although these vermicular agents have achieved good results in the production of ordinary vermicular graphite cast iron, they cannot meet the microstructure and performance requirements directly as vermicular agents for the production of non-magnetic vermicular graphite cast iron, because non-magnetic vermicular graphite cast iron contains Very high Mn, Ni and other alloying elements, these alloying elements have an important impact on the creep rate and inoculation effect, using the current vermicular agent and treatment method to produce non-magnetic vermicular graphite cast iron, the creep rate is less than 30%, and the inoculation effect Unsatisfactory or inducing recession, a large amount of cementite is produced, the processing performance is reduced, and the magnetic permeability is greatly increased, making it difficult for non-magnetic vermicular graphite cast iron to achieve or exert its due performance

[0005] (1) Regardless of the type of vermicular agent, when producing vermicular graphite cast iron, at least two processes of vermicularization and multiple inoculation must be performed separately, the operation is cumbersome and time-consuming, and the quality is not easy to control;

[0006] (2) The content of rare earth and magnesium is high, and the reaction is violent during the creeping process, but the absorption rate is low, resulting in the waste of a large amount of precious alloys, and the violent reaction produces a large amount of toxic smoke, which pollutes the environment;

[0007] (3) The control range of the amount of vermicularizing agent added is small, and it is easy to produce excessive amount to form spherical graphite, or too low to produce flake graphite, resulting in failure of vermicularization

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