Industrial alkali pickling method for nickel-based superalloy

Abstract

The invention discloses an industrial alkali pickling method for nickel-based superalloy. The industrial alkali pickling method comprises the following steps: 1, immersing a nickel-based superalloy plate into molten alkali liquor for alkali washing; secondly, the nickel-based high-temperature alloy plate subjected to alkali washing is soaked in water to be washed; thirdly, the washed nickel-based high-temperature alloy plate is soaked in a pickling solution to be subjected to pickling, and pickling is repeated till the natural color of metal is exposed; and fourthly, the nickel-based high-temperature alloy plate with the oxide skin removed is washed through a high-pressure water gun and then dried, and the nickel-based high-temperature alloy subjected to industrial alkali pickling is obtained. According to the method, oxide skin on the surface of the nickel-based high-temperature alloy plate is fully reacted through alkali washing, then the oxide skin is loosened through water washing, then the oxide skin is fully separated through repeated acid washing, finally, the oxide skin and an acid washing solution are completely washed through washing and dried, and the nickel-based high-temperature alloy plate with the oxide skin removed and good surface quality is obtained. The tolerance of the nickel-based high-temperature alloy plate pickled by the industrial alkali with the metal natural color is easy to guarantee, and the yield is high.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material surface chemical treatment in which the surface reacts with a reaction liquid, and in particular relates to a method for industrial alkaline pickling of a nickel-based high-temperature alloy. Background Art

[0002] High-temperature alloys are widely used in aerospace, energy, and shipbuilding fields because of their good high-temperature oxidation and corrosion resistance above 600°C, high high-temperature strength, creep strength, and endurance strength, as well as good fatigue resistance. Nickel-based high-temperature alloys have complex compositions, mostly containing elements such as Al and Cr. During hot rolling and heat treatment, a dense black oxide scale that is closely bonded to the matrix is ​​formed on the surface. Its structure is complex, usually Al 2 O 3 The main internal oxidation and Cr 2 O 3 It exists in a combination of external oxidation as the main oxidation, and is not easy to react with acid, making it difficult to remove the oxide scale of nickel-based high-temperature alloys.

[0003] In the prior art, there are two methods for removing the oxide scale on the surface of nickel-based high-temperature alloy plates, namely chemical method and physical method. The chemical method includes immersion method and wiping method. The invention patent with application number 201410709388.2 proposes to immerse the high-temperature alloy workpiece in a pickling solution below 30°C, and the pickling solution is: 300-400g / L hydrochloric acid, 400-450g / L nitric acid and 100-150g / L hydrogen peroxide, and the rest is water. This method is only applicable to small-sized workpieces. The temperature of the pickling solution must be guaranteed during the pickling process, which is dangerous. The invention patent with application number 201510221492.1 proposes to remove the oxide scale of the high-temperature alloy by wiping method. The pickling solution is: 66-88g / L hydrochloric acid, 50-67g / L hydrogen peroxide, 15-23g / L hydrofluoric acid, and the rest is water. This method is also only applicable to small-sized plates and is not suitable for mass production. The invention patent with application number 201310560864 proposes to soak the annealed and shot-blasted nickel-based high-temperature alloy in a 20-70℃ pickling solution for 10-2.5 hours. The pickling solution is: 190g / ~280g / L nitric acid, 10g~45g / L hydrofluoric acid, 10g~45g / L hydrochloric acid, 1~4g / L hexamethylenetetramine, and the rest is water. This method is a combination of physical and chemical methods. The surface roughness of the nickel-based high-temperature alloy plate obtained by this method is large and the color is dark, which is not conducive to the surface of the plate. The physical method mainly removes the oxide scale through mechanical means such as grinding and sanding, but it may introduce defects, the tolerance cannot be guaranteed, and the loss is relatively large.

[0004] Therefore, a method for obtaining the original metallic color of nickel-based high-temperature alloy plates by alkali washing and acid washing is proposed. This method has low requirements on the thickness and length and width of the nickel-based high-temperature alloy, is applicable to plates of general specifications, and can realize batch alkali acid washing of nickel-based high-temperature alloy plates. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for industrial alkali pickling of nickel-based high-temperature alloys in view of the deficiencies of the above-mentioned prior art. The method allows the oxide scale on the surface of the nickel-based high-temperature alloy plate to fully react with the molten alkali solution through alkali pickling, then loosens the oxide scale on the surface of the nickel-based high-temperature alloy plate through water washing, and then fully removes the oxide scale on the surface of the nickel-based high-temperature alloy plate through repeated pickling, and finally completely rinses the oxide scale and the pickling solution through rinsing and drying to remove the oxide scale, thereby obtaining a nickel-based high-temperature alloy with metallic color after industrial alkali pickling.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for industrial alkaline pickling of nickel-based high-temperature alloys, characterized in that the method comprises the following steps:

[0007] Step 1: Alkali washing: completely immerse the nickel-based high-temperature alloy plate in molten alkali solution for 10 to 20 minutes;

[0008] Step 2: Washing: completely immerse the alkali-washed nickel-based high-temperature alloy plate in water for 1 to 3 minutes;

[0009] Step 3: Pickling: Immerse the washed nickel-based high-temperature alloy plate completely in the pickling solution for pickling for 60 to 90 minutes, then lift it out to check the oxide scale, and repeat the pickling until the original color of the metal is exposed;

[0010] Step 4: Rinse and dry: Use a high-pressure water gun to fully rinse the surface of the nickel-based high-temperature alloy plate after removing the oxide scale, and then dry it to obtain the nickel-based high-temperature alloy after industrial alkali pickling.

[0011] The present invention uses alkali washing to make the oxide scale on the surface of the nickel-based high-temperature alloy plate fully react with the molten alkali solution, then uses water washing to loosen the oxide scale on the surface of the nickel-based high-temperature alloy plate, and then repeatedly performs pickling to fully remove the oxide scale on the surface of the nickel-based high-temperature alloy plate, and repeatedly lifts out the nickel-based high-temperature alloy plate during pickling to check the oxide scale. When the oxide scale is removed, the pickling process is stopped to improve efficiency, and finally the oxide scale and the pickling solution are completely rinsed and dried, so as to obtain the nickel-based high-temperature alloy after industrial alkali pickling with metallic color.

[0012] The above-mentioned method for industrial alkaline pickling of nickel-based high-temperature alloys is characterized in that the nickel-based high-temperature alloy plate in step 1 has a thickness greater than 0.5 mm, a width of 100 mm to 1000 mm, and a length of 500 mm to 3000 mm. The present invention is suitable for alkaline pickling of large-sized nickel-based high-temperature alloy plates.

[0013] The above-mentioned method for industrial alkaline pickling of nickel-based high-temperature alloys is characterized in that the molten alkali solution in step 1 is composed of a mixture of 80% to 90% by weight of sodium hydroxide and the remainder of sodium nitrate, and the temperature of the molten alkali solution is 500°C to 600°C. In the present invention, the oxide scale of the nickel-based high-temperature alloy is relatively sensitive to the temperature of the alkali pool, and basically does not react when the temperature is too low, and the subsequent long-term pickling and soaking of the oxide scale cannot effectively remove it. Therefore, the present invention controls the temperature and composition of the molten alkali solution to convert the oxide scale of the nickel-based high-temperature alloy into a substance soluble in water and acid under the joint action of sodium hydroxide and sodium nitrate at 500°C to 600°C, and the oxide scale can be effectively removed by subsequent water washing and pickling.

[0014] The above-mentioned method for industrial alkaline pickling of nickel-based high-temperature alloys is characterized in that the pickling solution in step 3 is composed of 30% to 40% by weight of nitric acid, 10% to 13% by weight of hydrofluoric acid, and the balance of water. In the present invention, the nickel-based high-temperature alloy is dissolved in the pickling solution, mainly by electrochemical corrosion, hydrofluoric acid mainly removes oxide scale, nitric acid can reduce the corrosion of hydrofluoric acid on the nickel-based high-temperature alloy, and plays a passivation role. The two complement each other to obtain a nickel-based high-temperature alloy with metallic color.

[0015] The above-mentioned method for industrial alkaline pickling of nickel-based high-temperature alloys is characterized in that the number of repeated pickling described in step 3 is 2 to 4 times, and the total pickling time is 120 minutes to 360 minutes. The nickel-based high-temperature alloy in the present invention needs to be annealed during preparation. The temperature and time of annealing will lead to different thicknesses of the oxide layer, and the oxide scale of the nickel-based high-temperature alloy is relatively complex, which is divided into internal oxidation and external oxidation. The present invention can remove the oxide scale on the surface of the nickel-based high-temperature alloy prepared under different process conditions by controlling the number and time of pickling.

[0016] The above-mentioned method for industrial alkaline pickling of nickel-based high-temperature alloys is characterized in that the checking of the oxide scale in step 3 is: the pickling is stopped when the oxide scale on the surface of the pickled high-temperature alloy plate is wiped off by external force to expose the original color of the metal. In the present invention, when the oxide scale on the surface of the pickled high-temperature alloy plate is wiped off by external force to expose the original color of the metal, it is considered that the oxide scale on the surface of the high-temperature alloy plate is in a detached state, and it can be removed by subsequent washing with a high-pressure water gun.

[0017] The above-mentioned method for industrial alkaline pickling of nickel-based high-temperature alloys is characterized in that the drying in step 4 is carried out in a drying box with a hot air temperature of 120°C to 180°C for 10 minutes to 50 minutes. The present invention controls the temperature and time of drying to fully remove the residual water on the surface and prevent watermarks from being left on the surface of the plate.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The present invention uses alkali washing to make the oxide scale on the surface of the nickel-based high-temperature alloy plate fully react with the molten alkali solution, then uses water washing to loosen the oxide scale on the surface of the nickel-based high-temperature alloy plate, and then repeatedly performs pickling to fully remove the oxide scale on the surface of the nickel-based high-temperature alloy plate, and repeatedly lifts out the nickel-based high-temperature alloy plate during pickling to check the oxide scale. When the oxide scale is removed, the pickling process is stopped to improve efficiency, and finally the oxide scale and the pickling solution are completely rinsed and dried, thereby obtaining a nickel-based high-temperature alloy with metallic color after industrial alkali pickling.

[0020] 2. The present invention is suitable for the production of nickel-based high-temperature alloy plates, and realizes batch alkaline pickling of nickel-based high-temperature alloy plates, solves the problem of inconvenient alkaline pickling in industrial production of nickel-based high-temperature alloy plates, and realizes alkaline pickling of large quantities of nickel-based high-temperature alloy plates.

[0021] 3. In the present invention, the oxide scale on the surface of the nickel-based high-temperature alloy after industrial alkali pickling is thoroughly cleaned, the surface is of metallic color, has high smoothness, is not blackened, has good surface quality, does not introduce other surface defects, is easy to ensure dimensional tolerance, and does not cause partial oxide scale not completely removed or over-corrosion.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a physical picture of the GH4169 high-temperature alloy obtained in Example 1 of the present invention after industrial alkali pickling. DETAILED DESCRIPTION

[0024] Example 1

[0025] This embodiment includes the following steps:

[0026] Step 1, alkali washing: 10 nickel-based high-temperature alloy plates of 2.5 mm × 620 mm × 2400 mm (thickness × width × length) are completely immersed in a molten alkali solution of 85% by weight sodium hydroxide and the remainder sodium nitrate at a temperature of 580° C. for 15 minutes;

[0027] Step 2: Washing: completely immerse the alkali-washed nickel-based high-temperature alloy plate in water for 3 minutes;

[0028] Step 3, pickling: the washed nickel-based high-temperature alloy plate is completely immersed in a pickling solution composed of 33% by weight nitric acid, 11% by weight hydrofluoric acid and the rest of water for pickling for 90 minutes, and then the surface oxide scale of the pickled high-temperature alloy plate is wiped off with a rag, and the process is repeated. After the pickling is repeated 4 times, the surface oxide scale is wiped off with a rag to reveal the original color of the metal to remove the oxide scale, and the pickling is stopped;

[0029] Step 4, rinsing and drying: The surface of the nickel-based high-temperature alloy plate after descaling is fully rinsed with a high-pressure water gun, and then dried in a drying oven at a hot air temperature of 150° C. for 30 minutes to obtain a nickel-based high-temperature alloy after industrial alkali pickling.

[0030] Figure 1 The actual picture of the GH4169 high temperature alloy after industrial alkali pickling obtained in this embodiment is shown in FIG. Figure 1 It can be seen that this embodiment processes multiple nickel-based high-temperature alloy plates at one time, realizing batch industrial alkali pickling of nickel-based high-temperature alloy plates, and the surface of the nickel-based high-temperature alloy after industrial alkali pickling is of metallic color, high smoothness, and no blackening occurs.

[0031] After testing, the oxide scale of the nickel-based high-temperature alloy prepared in this embodiment after industrial alkali pickling is completely removed, and it has the original color of the metal, high smoothness, no blackening, good surface quality, no other surface defects, easy to ensure dimensional tolerance, and no local oxide scale is not completely removed or over-corrosion.

[0032] Example 2

[0033] This embodiment includes the following steps:

[0034] Step 1, alkali washing: 10 nickel-based high-temperature alloy plates of 2.5 mm × 620 mm × 2400 mm (thickness × width × length) are completely immersed in a molten alkali solution of 85% by weight sodium hydroxide and the remainder sodium nitrate at a temperature of 500° C. for alkali washing for 20 minutes;

[0035] Step 2: Washing: completely immerse the nickel-based high-temperature alloy plate after alkali washing in water for 2 minutes;

[0036] Step 3, pickling: the washed nickel-based high-temperature alloy plate is completely immersed in a pickling solution composed of 36% by weight nitric acid, 12% by weight hydrofluoric acid and the rest of water for pickling for 80 minutes, and then the surface oxide scale of the pickled high-temperature alloy plate is wiped off with a rag, and the process is repeated. After the pickling is repeated 3 times, the surface oxide scale is wiped off with a rag to reveal the original color of the metal to remove the oxide scale, and the pickling is stopped;

[0037] Step 4, rinsing and drying: The surface of the nickel-based high-temperature alloy plate after descaling is fully rinsed with a high-pressure water gun, and then dried in a drying oven at a hot air temperature of 140° C. for 20 minutes to obtain a nickel-based high-temperature alloy after industrial alkali pickling.

[0038] After testing, the oxide scale of the nickel-based high-temperature alloy prepared in this embodiment after industrial alkali pickling is completely removed, and it has the original color of the metal, high smoothness, no blackening, good surface quality, no other surface defects, easy to ensure dimensional tolerance, and no local oxide scale is not completely removed or over-corrosion.

[0039] Example 3

[0040] This embodiment includes the following steps:

[0041] Step 1, alkali washing: 10 nickel-based high-temperature alloy plates of 2.5 mm × 620 mm × 2400 mm (thickness × width × length) are completely immersed in a molten alkali solution of 88% by weight sodium hydroxide and the remainder sodium nitrate at a temperature of 550° C. for 15 minutes;

[0042] Step 2: Washing: completely immerse the nickel-based high-temperature alloy plate after alkali washing in water for 2 minutes;

[0043] Step 3, pickling: the washed nickel-based high-temperature alloy plate is completely immersed in a pickling solution composed of 36% by weight nitric acid, 12% by weight hydrofluoric acid and the rest of water for pickling for 60 minutes, and then the surface oxide scale of the pickled high-temperature alloy plate is wiped off with a rag, and the process is repeated. After the pickling is repeated 4 times, the surface oxide scale is wiped off with a rag to reveal the original color of the metal to remove the oxide scale, and the pickling is stopped;

[0044] Step 4, rinsing and drying: The surface of the nickel-based high-temperature alloy plate after descaling is fully rinsed with a high-pressure water gun, and then dried in a drying oven at a hot air temperature of 150° C. for 10 min to 50 min to obtain a nickel-based high-temperature alloy after industrial alkali pickling.

[0045] After testing, the oxide scale of the nickel-based high-temperature alloy prepared in this embodiment after industrial alkali pickling is completely removed, and it has the original color of the metal, high smoothness, no blackening, good surface quality, no other surface defects, easy to ensure dimensional tolerance, and no local oxide scale is not completely removed or over-corrosion.

[0046] Example 4

[0047] This embodiment includes the following steps:

[0048] Step 1, alkali washing: 10 nickel-based high-temperature alloy plates of 2.5 mm × 620 mm × 2400 mm (thickness × width × length) are completely immersed in a molten alkali solution of 80% by weight sodium hydroxide and the remainder sodium nitrate at a temperature of 600° C. for alkali washing for 10 minutes;

[0049] Step 2: Washing: completely immerse the alkali-washed nickel-based high-temperature alloy plate in water for 1 minute;

[0050] Step 3, pickling: the washed nickel-based high-temperature alloy plate is completely immersed in a pickling solution composed of 40% by weight nitric acid, 10% by weight hydrofluoric acid and the rest of water for pickling for 70 minutes, and then the surface oxide scale of the pickled high-temperature alloy plate is wiped off with a rag, and the process is repeated. After the pickling is repeated twice, the surface oxide scale is wiped off with a rag to reveal the original color of the metal to remove the oxide scale, and the pickling is stopped;

[0051] Step 4, rinsing and drying: The surface of the nickel-based high-temperature alloy plate after descaling is fully rinsed with a high-pressure water gun, and then dried in a drying oven at a hot air temperature of 120° C. for 50 minutes to obtain a nickel-based high-temperature alloy after industrial alkali pickling.

[0052] After testing, the oxide scale of the nickel-based high-temperature alloy prepared in this embodiment after industrial alkali pickling is completely removed, and it has the original color of the metal, high smoothness, no blackening, good surface quality, no other surface defects, easy to ensure dimensional tolerance, and no local oxide scale is not completely removed or over-corrosion.

[0053] Example 5

[0054] This embodiment includes the following steps:

[0055] Step 1, alkali washing: 10 nickel-based high-temperature alloy plates of 2.5 mm × 620 mm × 2400 mm (thickness × width × length) are completely immersed in a molten alkali solution of 90% by weight sodium hydroxide and the remainder sodium nitrate at a temperature of 520° C. for alkali washing for 17 minutes;

[0056] Step 2: Washing: completely immerse the nickel-based high-temperature alloy plate after alkali washing in water for 2 minutes;

[0057] Step 3, pickling: the washed nickel-based high-temperature alloy plate is completely immersed in a pickling solution composed of 30% by weight nitric acid, 13% by weight hydrofluoric acid and the rest of water for pickling for 60 minutes, and then the surface oxide scale of the pickled high-temperature alloy plate is wiped off with a rag, and the process is repeated. After the pickling is repeated 3 times, the surface oxide scale is wiped off with a rag to reveal the original color of the metal to remove the oxide scale, and the pickling is stopped;

[0058] Step 4, rinsing and drying: The surface of the nickel-based high-temperature alloy plate after descaling is fully rinsed with a high-pressure water gun, and then dried in a drying oven at a hot air temperature of 180° C. for 40 minutes to obtain a nickel-based high-temperature alloy after industrial alkali pickling.

[0059] After testing, the oxide scale of the nickel-based high-temperature alloy prepared in this embodiment after industrial alkali pickling is completely removed, and it has the original color of the metal, high smoothness, no blackening, good surface quality, no other surface defects, easy to ensure dimensional tolerance, and no local oxide scale is not completely removed or over-corrosion.

[0060] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for industrial alkaline pickling of nickel-based high-temperature alloys, characterized in that: The method comprises the following steps: Step 1: Alkali washing: completely immerse the nickel-based high-temperature alloy plate in molten alkali solution for 10 to 20 minutes; Step 2: Washing: completely immerse the alkali-washed nickel-based high-temperature alloy plate in water for 1 to 3 minutes; Step 3: Pickling: Immerse the washed nickel-based high-temperature alloy plate completely in the pickling solution for pickling for 60 to 90 minutes, then lift it out to check the oxide scale, and repeat the pickling until the original color of the metal is exposed; Step 4: Rinse and dry: Use a high-pressure water gun to fully rinse the surface of the nickel-based high-temperature alloy plate after removing the oxide scale, and then dry it to obtain the nickel-based high-temperature alloy after industrial alkali pickling.

2. The method for industrial alkaline pickling of nickel-based high-temperature alloys according to claim 1, characterized in that: The nickel-based high-temperature alloy plate in step 1 has a thickness greater than 0.5 mm, a width of 100 mm to 1000 mm, and a length of 500 mm to 3000 mm.

3. The method for industrial alkaline pickling of nickel-based high-temperature alloys according to claim 1, characterized in that: The molten alkali solution in step 1 is composed of 80% to 90% by weight of sodium hydroxide and the remainder of sodium nitrate, and the temperature of the molten alkali solution is 500° C. to 600° C.

4. The method for industrial alkaline pickling of nickel-based high-temperature alloys according to claim 1, characterized in that: The pickling solution in step 3 is composed of 30% to 40% by weight of nitric acid, 10% to 13% by weight of hydrofluoric acid and the remainder of water.

5. The method for industrial alkaline pickling of nickel-based high-temperature alloys according to claim 1, characterized in that: The number of repeated pickling in step 3 is 2 to 4 times, and the total pickling time is 120 min to 360 min.

6. The method for industrial alkaline pickling of nickel-based high-temperature alloys according to claim 1, characterized in that: Checking the oxide scale in step 3 is as follows: the pickling is stopped when the oxide scale on the surface of the pickled high-temperature alloy plate is wiped off by external force to reveal the original color of the metal.

7. The method for industrial alkaline pickling of nickel-based high-temperature alloys according to claim 1, characterized in that: The drying in step 4 is carried out in a drying oven with a hot air temperature of 120° C. to 180° C. for 10 min to 50 min.

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