Surface treatment method for improving passivation quality of GH4169 material

Abstract

The invention relates to the technical field of high-temperature alloy surface treatment, in particular to a surface treatment method for improving the passivation quality of a GH4169 material, which comprises the following process steps: S1, carrying out ultrasonic cleaning in an ultrasonic degreasing tank; s2, performing electrochemical dissolution in an electrochemical treatment tank; s3, carrying out passivation treatment in a passivation solution; and S4, carrying out neutralization treatment in a neutralization treatment tank. According to the method, the removal efficiency of oxidation colors on the surfaces of high-temperature alloy finished products and semi-finished products subjected to vacuum heat treatment is improved, the hydrogen embrittlement tendency generated in the surface treatment process of the high-temperature alloy parts is completely eradicated, the problem that existing products are poor in appearance quality is solved, and the quality of passive film layers of the high-temperature alloy parts is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of high-temperature alloy surface treatment, and in particular relates to a surface treatment method for improving the passivation quality of GH4169 material. Background Art

[0002] High-temperature alloys have excellent high-temperature mechanical properties and are ideal materials in the field of aerospace manufacturing. They can prevent excessive oxidation and thermal corrosion of products during use. GH4169 is a nickel-based high-temperature alloy. In order to meet its strength requirements, vacuum aging heat treatment is generally used for the aging of finished and semi-finished parts. Although vacuum heat treatment is used, a light yellow oxidation color will still appear on the surface of the parts. This oxidation color must be removed before a dense oxide film can be generated on the surface of the parts through passivation treatment, thereby improving the corrosion resistance of high-temperature alloy parts. Otherwise, electrochemical corrosion will occur on the surface of the parts due to potential differences. Therefore, removing the oxidation color is crucial to ensuring the product quality of high-temperature alloy parts.

[0003] At present, pickling is used to remove the oxidation color on the surface of GH4169 high-temperature alloy after vacuum heat treatment. The pickling solution is a mixed acid of nitric acid + sulfuric acid + hydrofluoric acid or nitric acid + hydrofluoric acid. Since the strength of GH4169 material generally exceeds 1050MPa after vacuum heat treatment, the mixed acid pickling method is likely to cause hydrogen embrittlement of high-strength parts. Moreover, after 2-3 hours of pickling, the oxidation color removal effect is still not ideal, resulting in low quality of the passivation film and poor surface quality consistency, which affects product delivery.

[0004] Chinese patent CN113334256A "A method for cleaning nickel-based high-temperature alloys before welding" discloses a method for removing oxide scale. For high-temperature alloy parts after hot forming or heat treatment, a technical solution of sandblasting + wet glass shot blasting + pickling is adopted. The problem with this method is that sandblasting or wet glass shot blasting is not suitable for removing oxide scale from threaded parts or thin-walled parts, and pickling treatment is still required, which increases the risk of hydrogen embrittlement of high-strength steel. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a surface treatment method for improving the passivation quality of GH4169 material, thereby improving the removal efficiency of surface oxidation color of high-temperature alloy finished parts and semi-finished parts after vacuum heat treatment, eliminating the hydrogen embrittlement tendency generated during the surface treatment of high-temperature alloy parts, solving the problem of poor appearance quality of existing products, and improving the quality of the passivation film layer of high-temperature alloy parts.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A surface treatment method for improving the passivation quality of GH4169 material, comprising the following process steps:

[0008] S1. Perform ultrasonic cleaning in an ultrasonic degreasing tank at a temperature of 50-80°C for 5-10 minutes;

[0009] S2. Electrochemical dissolution is carried out in an electrochemical treatment tank with a current density of 5 to 10 A / dm 2 , temperature is 60~90℃, time is 5~10min;

[0010] S3, passivation treatment is carried out in a passivation solution at a temperature of 50-60°C and a passivation time of 30 minutes;

[0011] S4. Performing a neutralization treatment in a neutralization treatment tank, the treatment temperature is room temperature, and the neutralization time is 2 to 5 minutes.

[0012] Preferably, in S1, the ultrasonic cleaning solution comprises RK-2109 chemical degreasing powder with a concentration of 40 to 70 g / L.

[0013] Further preferably, the concentration of the chemical degreasing powder is 50 g / L.

[0014] Preferably, in S2, the components of the electrochemical dissolution solution are: 90-110 g / L of sodium hydroxide, 30-80 g / L of sodium carbonate, 60-80 g / L of sodium nitrite, and the solvent is water.

[0015] Further preferably, the solution composition of the electrochemical dissolution is: 100 g / L sodium hydroxide, 50 g / L sodium carbonate, 70 g / L sodium nitrite, and the solvent is water.

[0016] Preferably, in S3, the composition of the solution for passivation treatment is: 380-420 g / L nitric acid, 20-30 g / L sodium dichromate, and the solvent is water.

[0017] Further preferably, the solution composition of the passivation treatment is: 400 g / L nitric acid, 25 g / L sodium dichromate, and the solvent is water.

[0018] Preferably, in S4, the composition of the solution for neutralization treatment is: 30-100 g / L of sodium carbonate.

[0019] More preferably, the sodium carbonate is 65 g / L.

[0020] The present invention has the following advantages:

[0021] The present invention utilizes electrochemical dissolution to replace pickling, and the surface state after treatment is significantly better than the surface quality after pickling, and the anodic dissolution method is adopted, so there is no risk of hydrogen embrittlement. Furthermore, the passivation method of nitric acid + sodium dichromate is adopted, which has the advantages of short passivation time and high passivation film quality, so that the corrosion resistance of high-temperature alloy steel parts is significantly improved. After a 504h neutral salt spray test (3.5% NaCl solution), no rust spots are generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a photo of the high-temperature alloy bolt after vacuum heat treatment of the present invention;

[0023] Figure 2 This is a photo of a high-temperature alloy bolt treated by an embodiment of the present invention;

[0024] Figure 3 This is a photo of a high-temperature alloy bolt after being treated as a comparative example of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] The present invention provides a surface treatment method for improving the passivation quality of GH4169 material. The process principle for improving the passivation quality of high-temperature alloy parts is as follows: on the one hand, when the GH4169 material is immersed in an electrochemical solution at a certain temperature, an electrochemical reaction occurs on the surface of the part, and the oxygen generated by the anodic electrolysis promotes the oxidation of low-valent chromium oxides and nickel oxides into easily soluble high-valent oxides. The high-valent oxides can be dissolved in an alkaline solution to make the oxides loose, and the oxygen generated by the reaction has a mechanical stripping effect on the oxides, so that the bonding force between the metal and the oxides is relaxed, so that the oxidation color on the surface of the high-temperature alloy steel is removed, thereby obtaining a bright surface, and the main function of the oxidant sodium nitrite is to have a strong passivation effect on the high-temperature alloy to prevent the surface of the high-temperature alloy from being corroded, and further promote the transformation of low-valent oxides into high-valent oxides, so that the oxides are loose. On the other hand, a passivation solution of nitric acid + sodium dichromate can be used, and a strong oxidant sodium dichromate can be used to first form a thin passivation film on the surface of the part, and then the strong oxidizing property of nitric acid can be used to thicken the passivation film, so as to achieve a high corrosion resistance passivation.

[0028] Example 1

[0029] The high-temperature alloy parts were placed in an ultrasonic cleaning tank for cleaning. The ultrasonic cleaning solution was RK-2109 chemical degreasing powder with a concentration of 60 g / L, a temperature of 70°C, and a cleaning time of 10 min.

[0030] Wash with hot water and cold water for 3 to 4 times respectively; then put the high-temperature alloy parts in the electrochemical treatment tank. The composition of the electrochemical dissolution solution is: sodium hydroxide 100g / L, sodium carbonate 50g / L, sodium nitrite 65g / L, the solvent is water, and the current density is 10A / dm 2 , temperature is 70℃, time is 8min;

[0031] Wash with hot water and cold water for 3 to 4 times; then passivate the high-temperature alloy parts, the solution composition is: 400g / L nitric acid, 25g / L sodium dichromate, the solvent is water, the temperature is 52°C, and the passivation time is 30min;

[0032] After washing with cold water for 3 to 4 times, the high-temperature alloy parts are neutralized. The solution composition is: 70g / L sodium carbonate, the temperature is room temperature, and the neutralization time is 4min.

[0033] Wash with hot water and cold water 3 to 4 times, and finally wash with pure water 3 times; after drying with compressed air, put the parts into the drying box at a temperature of 100 to 120°C for 60-90 minutes.

[0034] Example 2

[0035] The high-temperature alloy parts were placed in an ultrasonic cleaning tank for cleaning. The ultrasonic cleaning solution was RK-2109 chemical degreasing powder with a concentration of 50 g / L, a temperature of 65°C, and a cleaning time of 8 min.

[0036] Wash with hot water and cold water for 3 to 4 times respectively; then put the high-temperature alloy parts in the electrochemical treatment tank. The composition of the electrochemical dissolution solution is: sodium hydroxide 110g / L, sodium carbonate 70g / L, sodium nitrite 70g / L, the solvent is water, and the current density is 8A / dm 2 , temperature is 80℃, time is 10min;

[0037] Wash with hot water and cold water for 3 to 4 times; then passivate the high-temperature alloy parts, the solution composition is: 390g / L nitric acid, 30g / L sodium dichromate, the solvent is water, the temperature is 55°C, and the passivation time is 30min;

[0038] After washing with cold water for 3 to 4 times, the high-temperature alloy parts are neutralized. The solution composition is: 50g / L sodium carbonate, the temperature is room temperature, and the neutralization time is 5min;

[0039] Wash with hot water and cold water 3 to 4 times, and finally wash with pure water 3 times; after drying with compressed air, put the parts into the drying box at a temperature of 100 to 120°C for 60-90 minutes.

[0040] Example 3

[0041] The high-temperature alloy parts were placed in an ultrasonic cleaning tank for cleaning. The ultrasonic cleaning solution was RK-2109 chemical degreasing powder with a concentration of 68 g / L, a temperature of 60°C, and a cleaning time of 8 min.

[0042] Wash with hot water and cold water for 3 to 4 times respectively; then put the high-temperature alloy parts in the electrochemical treatment tank. The composition of the electrochemical dissolution solution is: sodium hydroxide 105g / L, sodium carbonate 50g / L, sodium nitrite 75g / L, the solvent is water, and the current density is 9A / dm 2 , temperature is 90℃, time is 10min;

[0043] Wash with hot water and cold water for 3 to 4 times; then passivate the high-temperature alloy parts, the solution composition is: 410g / L nitric acid, 28g / L sodium dichromate, the solvent is water, the temperature is 55°C, and the passivation time is 30min;

[0044] After washing with cold water for 3 to 4 times, the high-temperature alloy parts are neutralized. The solution composition is: 90g / L sodium carbonate, the temperature is room temperature, and the neutralization time is 5min.

[0045] Wash with hot water and cold water 3 to 4 times, and finally wash with pure water 3 times; after drying with compressed air, put the parts into the drying box at a temperature of 100 to 120°C for 60-90 minutes.

[0046] Comparative Example

[0047] At present, the surface treatment process flow of high-temperature alloy parts after vacuum heat treatment is: organic solvent degreasing → chemical degreasing → water washing → pickling → water washing → passivation → water washing → neutralization → water washing → drying → inspection.

[0048] The experimental results are as follows: Figure 1 This is a GH4169 bolt after vacuum heat treatment. It can be observed that there is a layer of light yellow oxidation on the surface. Figure 2 The appearance of the GH4169 bolts after treatment in Examples 1 to 3 is bright in color. After 504h neutral salt spray test, there is no rust. Figure 3 This is the appearance after the comparative example treatment. It can be seen that the surface color is poor and there is unwashed oxidation color.

[0049] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A surface treatment method for improving the passivation quality of GH4169 material, characterized in that: The process steps include: S1. Perform ultrasonic cleaning in an ultrasonic degreasing tank at a temperature of 50 to 80°C for 5 to 10 minutes; S2. Electrochemical dissolution is carried out in an electrochemical treatment tank with a current density of 5 to 10 A / dm 2 , temperature is 60~90℃, time is 5~10min; S3, passivation treatment is carried out in a passivation solution at a temperature of 50-60°C and a passivation time of 30 minutes; S4. Performing a neutralization treatment in a neutralization treatment tank, the treatment temperature is room temperature, and the neutralization time is 2 to 5 minutes.

2. A surface treatment method for improving the passivation quality of GH4169 material according to claim 1, characterized in that: In S1, the ultrasonic cleaning solution is composed of RK-2109 chemical degreasing powder with a concentration of 40 to 70 g / L.

3. A surface treatment method for improving the passivation quality of GH4169 material according to claim 2, characterized in that: The concentration of the chemical degreasing powder is 50 g / L.

4. A surface treatment method for improving the passivation quality of GH4169 material according to claim 1, characterized in that: In S2, the composition of the electrochemical dissolution solution is: 90-110 g / L of sodium hydroxide, 30-80 g / L of sodium carbonate, 60-80 g / L of sodium nitrite, and the solvent is water.

5. A surface treatment method for improving the passivation quality of GH4169 material according to claim 4, characterized in that: The solution composition of the electrochemical dissolution is: 100 g / L sodium hydroxide, 50 g / L sodium carbonate, 70 g / L sodium nitrite, and the solvent is water.

6. A surface treatment method for improving the passivation quality of GH4169 material according to claim 1, characterized in that: In S3, the solution composition of the passivation treatment is: 380-420 g / L of nitric acid, 20-30 g / L of sodium dichromate, and the solvent is water.

7. A surface treatment method for improving the passivation quality of GH4169 material according to claim 6, characterized in that: The solution composition of the passivation treatment is: 400g / L nitric acid, 25g / L sodium dichromate, and the solvent is water.

8. A surface treatment method for improving the passivation quality of GH4169 material according to claim 1, characterized in that: In S4, the composition of the solution for neutralization treatment is: 30-100 g / L of sodium carbonate.

9. A surface treatment method for improving the passivation quality of GH4169 material according to claim 8, characterized in that: The sodium carbonate is 65g / L.

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