Preparation method of precision-investment casting single-crystal high-temperature alloy thin-wall sample

Abstract

The invention relates to a preparation method of a precision-investment casting single-crystal high-temperature alloy thin-wall sample. In the wax mould preparation process, a plate-shaped ceramic core is put into a mould, and the ceramic core is used as a support of wax; the mould is closed, the wax is injected into the mould, the injection pressure of the wax ranges from 5 bar to 8 bar, the temperature of the wax ranges from 60 DEG C to 80 DEG C, and the pressure maintaining time ranges from 60 s to 120 s; and wax moulds of a certain thickness are formed on the two sides of the plate-shaped ceramic core, and the wax moulds are closely attached to the surface of the ceramic core. According to the thickness of the designed thin-wall sample, the wax moulds on the two sides of the ceramic core are thinned, the rotating speed of a spindle is controlled to range from 500 r/min to 6,000 r/min, the feed speed is controlled to range from 30 mm/min to 450 mm/min, and the axial cutting depth is controlled to range from 0.03 mm to 0.5 mm. The wax moulds of the thin-wall sample are prepared, after a mould set is formed by the wax moulds of the thin-wall sample, a shell is prepared through shell coating, directional solidification pouring is completed in a vacuum induction single crystal furnace, and therefore the single-crystal high-temperature alloy precision casting thin-wall sample is prepared. According to the preparation method, the problems of short run and undercasting of the wax moulds in the deformation and directional solidification process in the mould pick-up and finishing process can be completely avoided.

Description

technical field [0001] The invention relates to a method for preparing a thin-walled sample of a single-crystal superalloy by investment casting precision casting. Background technique [0002] With the continuous improvement of the thrust-to-weight ratio (power-to-weight ratio) of aviation gas turbine engines, the temperature in front of the turbine is getting higher and higher, which makes the inner cavity structure design of single crystal superalloy air-cooled turbine blades more complex, and the blade wall thickness is getting thinner and thinner. And adopt thin trailing edge structure to reduce aerodynamic loss. Whether the performance of the single crystal superalloy will change under the condition of thin-walled structure, whether it can reach the performance of the standard sample, that is, whether the single crystal superalloy has a thin-wall effect, this is important for the reliability design and performance of single crystal superalloy turbine blades. Long life...

AI Technical Summary

Problems solved by technology

In the wax mold preparation process, when the thickness of the pressed wax mold is less than 1mm, the strength of the wax mold is low. If there is no core support, the wax mold is easily deformed during the process of taking out from the mold, trimming, and shell coating, resulting in The finally prepared single crystal superalloy precision cast thin-walled sample has large deformation, even bending and warping, which cannot meet the requirements of parallelism and coaxiality for the thin-walled sample in the mechanical performance test; in the process of shell preparation, Although increasing the number of coating layers is beneficial to improve the high temperature strength of the shell, too many coating layers will significantly reduce the collapse of the shell and increase the solidification residual stress of thin-walled samples. Recrystallization is easy to occur during the process, resulting in the scrapping of precision cast thin-walled samples; during the directional solidification process, when the temperature of the upper and lower heaters is low and the holding time of the mold shell is too short, the flow of the alloy metal liquid in the mold shell Insufficient pouring and under-casting of thin-walled samples are prone to occur, and when the pulling speed control is unreasonable, thin-walled samples are prone to defects such as miscellaneous crystals and large-angle grain boundaries

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