Process and device for high-temperature alloy fine-grain casting with composite electromagnetic fields

Abstract

Disclosed are a process and a device for high-temperature alloy fine-grain casting with composite electromagnetic fields. The device is characterized in that two electromagnetic fields generators are arranged on the upper portion and the lower portion of the outside of an austenitic stainless steel sand box sequentially, wherein a steady direct-current electromagnetic field generator is arranged on the upper portion, and a bidirectional low-frequency alternating-current rotary electromagnetic field generator is arranged on the lower portion. A bidirectional rotary electromagnetic field is generated after bidirectional low-frequency alternating-current power is input into the bidirectional low-frequency rotary electromagnetic field generator on the lower portion of the austenitic stainless steel sand box, and grains of vacuum precision high-temperature alloy castings can be refined until the diameter of grains is 95 mu m and the section isometric crystal proportion reaches 100% under the bidirectional rotary electromagnetic stirring action generated in metal liquid. A steady direct-current electromagnetic field is generated by the steady direct-current electromagnetic field generator after the steady direct-current electromagnetic field generator is input with direct-current power, and electromagnetic brake power generated on the metal liquid level by the direct-current electromagnetic field suppresses sharp fluctuation of the metal liquid level caused by internal electromagnetic stirring action, and adverse affection of fluctuation of metal liquid level onto floating of inclusion and shrinkage cavity feeding during the solidification process of high-temperature alloy castings is eliminated.

Description

technical field [0001] The invention belongs to the field of metal material preparation, and in particular relates to a high-temperature alloy fine-grain casting process method and device for applying a compound electromagnetic field. Background technique [0002] The service temperature of high-temperature alloy parts such as low-pressure turbine blades and casings of aero-engines and turbine disks of industrial gas turbines is mostly below the iso-strength temperature of 760°C, so it is hoped that the casting structure will be uniform and fine equiaxed crystals as a whole to improve its fatigue resistance. . In order to refine the grain structure of cast superalloys, three high-temperature superalloy fine-grained casting techniques, namely thermal control method, mechanical method and chemical method, have been developed at home and abroad. The thermal control method is to control the heat flow of crystallization during the solidification process, that is, to use low mel...

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Problems solved by technology

However, this method has a limited effect on the refinement of the solidification structure of superalloy castings, especially when the molten metal is not poured into the mold, electromagnetic stirring is performed, which will cause large fluctuations in the upper surface of the molten metal, and the molten metal will Under the action, it will climb along the mold wall and then solidify to form a large flash, which deteriorates the shrinkage and shrinkage conditions of the casting during solidification.

[0004] In 2008, the applicant proposed in the article "Grain refinement of K417 superalloy under the action of electromagnetic field and surface inoculant" published in "Rare Metal Materials and Engineering" to apply bidirectional rotating electromagnetic stirring and surface The method of combining inoculants to achieve grain refinement of the solidification structure of superalloys can refine the solidification structure of superalloy castings to 0.1mm, but this method solves the problem of molten metal just pouring by delaying the start time of electromagnetic stirring. Rotating electromagnetic stirring after entering the mold will lead to relatively large fluctuations in the liquid metal level without forming a surface solidification shell. Under the action of electromagnetic force, the molten metal will rise along the mold wall and then solidify to form large flashes, which will deteriorate the solidification process of the casting. Because of the problem of shrinkage cavity feeding conditions, it is difficult to obtain high-temperature alloy fine-grained castings with a section equiaxed grain ratio of 100% by using this method

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