Chemical milling method for monocrystalline high temperature alloy precision casting

A technology for high-temperature alloys and precision castings, applied in the field of high-temperature alloys, can solve problems such as chemical milling of alloy castings that cannot contain Re, achieve the effects of increasing yield, simple operation, and reducing recrystallization defects

Inactive Publication Date: 2013-12-18
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method cannot be used for chemical milling of Re-containing alloy castings.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] Weigh 500ml of distilled water, 220ml of hydrofluoric acid, and 240ml of nitric acid to prepare a corrosion solution and mix well.

[0019] Put a group of as-cast DD5 precision casting blades and single crystal test pieces prepared by the same process into the corrosion tank at the same time, then pour the corrosion solution into the corrosion tank to ensure that the corrosion solution is immersed in the casting, and heat it in a water bath outside the corrosion tank, and Measure the temperature of the corrosive solution between 20-60°C. The chemical milling time is about 100min. Rinse with clean water to remove surface residue. Use a micrometer to measure the thickness of the test piece and reduce it by 0.1 mm. Under this condition, the surface of the investment casting is about 0.05 mm thick.

Embodiment 2

[0021] Weigh 600ml of distilled water, 300ml of hydrofluoric acid, and 200ml of nitric acid to prepare a corrosion solution and mix well.

[0022] Put a group of heat-treated DD5 precision castings into the corrosion tank, then pour the corrosion solution into the corrosion tank, so that the corrosion solution is immersed in the castings, heat it with a temperature-controllable electric furnace under the corrosion tank, and keep the temperature of the corrosion solution at 20-60°C between. The chemical milling time is about 150min. Rinse with clean water to remove corrosion products. Visually observe the uniform corrosion on the casting surface. The thickness of the test piece was reduced by 0.12 mm, that is, the surface of the casting was removed by about 0.06 mm.

Embodiment 3

[0024] A group of DD32 single crystal superalloy test pieces whose surface had been sandblasted were subjected to chemical milling treatment according to Example 1, and then solution treatment, and at the same time, the test pieces without chemical milling were also subjected to solution treatment for comparison. The microstructure observation of the section shows that there is a recrystallization layer with a thickness of about 30 μm on the surface of the unmilled test piece, while no recrystallization layer is observed on the chemically milled test piece.

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Abstract

The invention relates to a chemical milling method for monocrystalline high temperature alloy precision casting. The method is as below: first cleaning impurities on the surface of the precision casting; then putting a corrosion liquid and a precision casting in a corrosion groove, putting in a test piece with known thickness, immersing the precision casting and the test piece in the corrosion liquid, heating the corrosion groove from outside to maintain the temperature of the corrosion liquid at 20-60 DEG C, corroding for 90-200 min to shed off the corrosion products; taking out the precision casting and the test piece from the corrosion groove, flushing the precision casting and the test piece with clear water, brushing off residual corrosion products, air-drying the precision casting and the test piece, measuring thickness change of the test piece and determining the removal amount of the casting; and if the removal amount is not enough, repeating the above steps until a required removal amount is reached. The method provided by the invention is mainly suitable for chemical milling of Re-containing nickel base monocrystalline high temperature alloy. The chemical milling method is mainly used for removal of local stress concentration on the surface layer of the casting in a casting technology, and can effectively alleviate defect of recrystallization in a subsequent heat treatment process.

Description

technical field [0001] The invention belongs to the technical field of high-temperature alloys, and in particular relates to a chemical milling method for precision castings of single-crystal high-temperature alloys. Background technique [0002] In order to meet the increasing thrust-to-weight ratio and energy-saving and environmental protection requirements of aero-engines, superalloys, the most important heat-bearing parts in engines, have developed from polycrystalline oriented alloys and single-crystalline alloys. Single crystal alloys have greatly improved properties due to the removal of grain boundaries that weaken at high temperatures. In order to obtain better performance, single crystal superalloys have experienced from the first generation of Re-free alloys to the second generation of 3% Re alloys, to the third generation of 6% Re alloys and the latest development of the fourth generation Alloys with Ru added on the basis of high Re. The addition of Re signific...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23F1/28C30B33/10
Inventor 孟杰王亮李金国周亦胄金涛孙晓峰王猛徐福涛李博
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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