Corrosion method of AlSi10Mg alloy grain boundary

Abstract

The invention discloses a corrosion method of an Al Si 10Mg alloy grain boundary, which mainly comprises the following steps of: 1, preparing a corrosion liquid which comprises the following components: 150mL of NaOH, 8-10g of NaOH and 3-5g of NaOH; 2, embedding an Al Si 10Mg sample; thirdly, the embedded samples are sequentially polished with abrasive paper from 400 meshes to 7000 meshes; 4, roughly polishing the ground sample; 5, smearing a surfactant on the sample subjected to rough polishing, and then carrying out fine polishing; 6, cleaning the polished sample with industrial alcohol; 7, heating the prepared corrosive liquid to 60-80 DEG C, and corroding the sample for 40-60 seconds; 8, cleaning the sample with industrial alcohol after corrosion patterns appear on the surface of the sample; and 9, carrying out drying treatment. After the method is used for corroding the Al Si 10Mg alloy, the crystal boundary of the alloy can be clearly observed, and the method is low in equipment requirement, simple in operation step, capable of saving cost, good in stability and suitable for researching the grain morphology, the grain size, the microstructure performance and the like of the Al S i 10Mg alloy.

Description

Technical Field

[0001] The invention relates to the technical field of AlSi10Mg metallographic corrosion, in particular to a method for corroding grain boundaries of an AlSi10Mg alloy. Background Art

[0002] When studying the effects of grain morphology and size on alloy properties in metal SLM 3D printing of AlSi10Mg, it's often necessary to observe grain boundaries. A common method involves electropolishing followed by electron backscatter diffraction (EBSD). This involves sample preparation, followed by EBSD observation. The sample preparation process is complex and tedious, and requires high equipment requirements, increasing both the time and cost of research. The polishing and etching steps are crucial for sample preparation.

[0003] AlSi10Mg alloy, composed primarily of Al, Si, and Mg, is a heat-treatable, hardened aluminum alloy with excellent fluidity, high density in printed parts, and a low cracking profile. Due to its excellent casting properties, high strength and hardness, good dynamic properties, superior corrosion resistance, and unique microstructure, it is widely used in the marine, aerospace, and rail transportation sectors. However, precisely because this alloy exhibits superior corrosion resistance compared to other non-rust-resistant aluminum alloys, it is difficult to obtain its metallographic structure using conventional etching methods after 3D printing. Furthermore, the limited difference between grain boundaries and the interior of the grains further complicates etching the grain boundaries of AlSi10Mg alloy. Consequently, when studying the effects of grain morphology and size on alloy properties, the difficulty of etching grain boundaries leads to poor sample preparation, increased time and financial costs, and hinders research on the effects of grain morphology and size on alloy properties. Therefore, developing a convenient and easy-to-use etching solution and etching method for etching grain boundaries in AlSi10Mg alloy is essential.

[0004] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the above technical defects and provide a method for corroding the grain boundaries of AlSi10Mg alloy. The grain boundaries obtained by corrosion are clearly visible, which effectively saves time and economic costs and is conducive to studying the influence of the grain morphology and size of AlSi10Mg alloy on the alloy properties.

[0006] In order to solve the above problems, the technical solution of the present invention is a method for corroding the grain boundaries of an AlSi10Mg alloy, comprising the following steps:

[0007] Step 1: Prepare the corrosive solution;

[0008] Step 2: Inlaying: Inlaying the AlSi10Mg sample;

[0009] Step 3: Polishing: After the mounted sample cools down, polish the mounted sample with sandpaper from 400 mesh to 7000 mesh;

[0010] Step 4: rough polishing, pre-polishing the polished sample;

[0011] Step 5: Fine polishing: Apply surfactant to the rough-polished sample and then perform fine polishing;

[0012] Step 6: Clean the polished sample with industrial alcohol.

[0013] Step 7: Corrosion: Blow dry the cleaned sample, immerse the AlSi10Mg sample in a 60-80°C corrosive solution at room temperature and corrode for 40-60 seconds;

[0014] Step 8: Secondary cleaning: When corrosion patterns appear on the surface of the sample, clean it with industrial alcohol;

[0015] Step 9: Drying: Use a hair dryer to dry the sample.

[0016] Furthermore, in step 1, the etching solution comprises the following ingredients: 150 mL H2O+8-10 g KMnO4+3-5 g NaOH, and the purity of KMnO4 and NaOH are both 99.0%.

[0017] Furthermore, in step 1, the etching solution is prepared as follows: water, KMnO4, and NaOH are added in the formula ratio in sequence.

[0018] Furthermore, in step 2, the inlay method is cold inlay using phenolic resin powder, the inlay temperature is room temperature, and the inlay is placed in a ventilated location for 15 minutes.

[0019] Furthermore, in step three, the polishing method is to use 400 mesh, 800 mesh, 1200 mesh, 1500 mesh, 2000 mesh, 3000 mesh, 5000 mesh, and 7000 mesh sandpaper in sequence for polishing under water.

[0020] Furthermore, in step 4, the pre-polishing step is to use a cashmere polishing cloth and a silica polishing liquid with a particle size of 0.1 μm to perform rough polishing until the polishing marks are formed and the directions of the polishing marks are consistent.

[0021] Furthermore, in step five, the fine polishing step is to apply a surfactant to the rough polishing sample and then use a cashmere polishing cloth and a silica polishing liquid with a particle size of 0.05 μm to perform fine polishing until the surface has a mirror gloss and there are no polishing marks when observed under an optical microscope.

[0022] The advantages of the present invention compared with the existing technology are:

[0023] 1. The corrosion liquid and the corrosion method of the present invention are used to corrode AlSi10Mg alloy, with good corrosion effect, clearly visible grain boundaries, and good observation effect under an optical microscope. The equipment requirements are low and the operation steps are simple, which effectively saves time and economic costs and is conducive to studying the influence of grain morphology and size of AlSi10Mg alloy on alloy properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a metallographic structure photograph obtained by etching in Example 1 of the present invention;

[0025] Figure 2 This is a metallographic structure photograph obtained by etching in Example 2 of the present invention;

[0026] Figure 3 This is a metallographic structure photograph etched out of comparative example 1 of the present invention. DETAILED DESCRIPTION

[0027] In order to make the contents of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0028] Example 1:

[0029] The method for intergranular corrosion of AlSi10Mg alloy comprises the following steps:

[0030] Step 1: Prepare a corrosion solution with the following ingredients: 150 mL H2O + 8-10 g KMnO4 + 3-5 g NaOH; the purity of both KMnO4 and NaOH is 99.0%, and water, KMnO4, and NaOH are added in the formula proportions in sequence;

[0031] Step 2: Mounting the AlSi10Mg sample: cold mounting the AlSi10Mg alloy sample in a mounting mold using phenolic resin powder at room temperature for 15 minutes.

[0032] Step 3: Polishing: After the mounted sample has cooled, polish the mounted sample with sandpaper from low to high mesh; use 400 mesh, 800 mesh, 1200 mesh, 1500 mesh, 2000 mesh, 3000 mesh, 5000 mesh, and 7000 mesh sandpaper in sequence for polishing under running water;

[0033] Step 4: Rough polishing: First, use a cashmere polishing cloth and a silica polishing liquid with a particle size of 0.1 μm to perform rough polishing until the polishing marks are clear and the directions of the polishing marks are consistent;

[0034] Step 5: Fine polishing: Use a cashmere polishing cloth and a silica polishing liquid with a particle size of 0.05 μm to perform fine polishing until the surface has a mirror finish and there are no polishing marks when observed under an optical microscope;

[0035] Step 6: Clean the polished sample with industrial alcohol.

[0036] Step 7: Corrosion: Blow dry the cleaned sample, immerse the AlSi10Mg sample in a 60-80°C corrosive solution at room temperature and corrode for 40-50 seconds;

[0037] Step 8: Secondary cleaning: clean the corroded sample again with industrial alcohol;

[0038] Step 9: Drying: Use a hair dryer to dry the sample.

[0039] The sample corroded by the above method was placed under a microscope for observation, and the metallographic structure was observed as follows. Figure 1 As shown, it can be seen that the grain boundaries of the alloy are clear and complete, the corrosion effect is good, and it is easy to observe.

[0040] Example 2:

[0041] The method for intergranular corrosion of AlSi10Mg alloy comprises the following steps:

[0042] Step 1: Prepare a corrosion solution with the following ingredients: 150 mL H2O + 8-10 g KMnO4 + 3-5 g NaOH; the purity of both KMnO4 and NaOH is 99.0%, and water, KMnO4, and NaOH are added in the formula proportions in sequence;

[0043] Step 2: Mounting the AlSi10Mg sample: cold mounting the AlSi10Mg alloy sample in a mounting mold using phenolic resin powder at room temperature for 15 minutes.

[0044] Step 3: Polishing: After the mounted sample has cooled, polish the mounted sample with sandpaper from low to high mesh; use 400 mesh, 800 mesh, 1200 mesh, 1500 mesh, 2000 mesh, 3000 mesh, 5000 mesh, and 7000 mesh sandpaper in sequence for polishing under running water;

[0045] Step 4: Rough polishing: First, use a cashmere polishing cloth and a silica polishing liquid with a particle size of 0.1 μm to perform rough polishing until the polishing marks are clear and the directions of the polishing marks are consistent;

[0046] Step 5: Fine polishing: Use a cashmere polishing cloth and a silica polishing liquid with a particle size of 0.05 μm to perform fine polishing until the surface has a mirror finish and there are no polishing marks when observed under an optical microscope;

[0047] Step 6: Clean the polished sample with industrial alcohol.

[0048] Step 7: Corrosion: Blow dry the cleaned sample, immerse the AlSi10Mg sample in a 60-80°C corrosive solution at room temperature and corrode for 40-60 seconds;

[0049] Step 8: Secondary cleaning: clean the corroded sample again with industrial alcohol;

[0050] Step 9: Drying: Use a hair dryer to dry the sample.

[0051] The sample corroded by the above method was placed under a microscope for observation, and the metallographic structure was observed as follows. Figure 2 As shown, the grain boundaries of the alloy are clear, complete, and uniform, the corrosion effect is good, and it is easy to observe. Figure 1 More neat.

[0052] Comparative Example 1:

[0053] The etching solution was Keller reagent, the etching temperature was room temperature, and the etching time was 30 s.

[0054] First, the AlSi10Mg alloy specimen was cold mounted in a mounting mold using phenolic resin powder. The mounting temperature was room temperature and the mounting time was 15 minutes. After the mounted specimen cooled, it was polished with 400 mesh, 800 mesh, 1000 mesh, 1200 mesh, 1500 mesh, 2000 mesh, 3000 mesh, 5000 mesh, and 7000 mesh sandpaper respectively. Then, it was coarsely polished with a cashmere polishing cloth and a silica polishing liquid with a particle size of 0.1 μm. After the scratches were consistent in direction, it was finely polished with a cashmere polishing cloth and a silica polishing liquid with a particle size of 0.05 μm until the surface had a mirror gloss and no polishing marks were observed under an optical microscope. The polished specimen was cleaned with alcohol, blown dry, and immersed in a corrosive solution for 30 seconds. When corrosion patterns appeared on the specimen surface, it was cleaned with industrial alcohol, blown dry, and observed under a microscope.

[0055] The sample corroded by the above method was placed under a microscope for observation, and the metallographic structure was observed as follows. Figure 3 As shown, some precipitation phases of AlSi10Mg can be seen, but the grain boundaries are very vague and the corrosion effect is poor.

[0056] The above description of the present invention and its embodiments is non-limiting. In short, if a person skilled in the art is inspired by the above description and designs a similar structure and embodiment to the technical solution without departing from the purpose of the present invention, they should fall within the scope of protection of the present invention.

Claims

1. A method for corroding grain boundaries of an AlSi10Mg alloy, characterized in that: The following steps are involved: Step 1: Prepare the corrosive solution; Step 2: Mounting: Mounting the AlSi 10Mg sample; Step 3: Polishing: After the mounted sample cools down, polish the mounted sample with sandpaper from 400 mesh to 7000 mesh; Step 4: rough polishing, pre-polishing the polished sample; Step 5: Fine polishing: Apply surfactant to the rough-polished sample and then perform fine polishing; Step 6: Clean the polished sample with industrial alcohol. Step 7: Corrosion: Blow dry the cleaned sample, and immerse the AlSi 10Mg sample in a 60-80°C corrosive solution at room temperature for 40-60 seconds. Step 8: Secondary cleaning: When corrosion patterns appear on the surface of the sample, clean it with industrial alcohol; Step 9: Drying: Use a hair dryer to dry the sample.

2. The method for corroding grain boundaries of an AlSi10Mg alloy according to claim 1, characterized in that: In step 1, the etching solution is prepared by mixing 150 mL H2O + 8-10 g KMnO4 + 3-5 g NaOH, wherein the purity of the KMnO4 and NaOH are both 99.0%.

3. The method for corroding grain boundaries of an AlSi10Mg alloy according to claim 1, characterized in that: In step 1, the etching solution is prepared as follows: water, KMnO4, and NaOH are added in the formula ratio in sequence.

4. The method for corroding grain boundaries of an AlSi10Mg alloy according to claim 1, wherein: In step 2, the mounting method is cold mounting using phenolic resin powder, the mounting temperature is room temperature, and the specimen is placed in a ventilated location for 15 minutes.

5. The method for corroding grain boundaries of an AlSi10Mg alloy according to claim 1, characterized in that: In step three, the polishing method is to use 400 mesh, 800 mesh, 1200 mesh, 1500 mesh, 2000 mesh, 3000 mesh, 5000 mesh, and 7000 mesh sandpaper in sequence for polishing under water.

6. The method for corroding grain boundaries of an AlSi10Mg alloy according to claim 1, characterized in that: In step 4, the pre-polishing step is to use a cashmere polishing cloth and a silicon dioxide polishing liquid with a particle size of 0.1 μm to perform rough polishing until the polishing marks are formed and the directions of the polishing marks are consistent.

7. The method for corroding grain boundaries of an AlSi10Mg alloy according to claim 1, characterized in that: In step five, the fine polishing step is to apply a surfactant to the rough polishing sample and then use a cashmere polishing cloth and a silica polishing liquid with a particle size of 0.05 μm to perform fine polishing until the surface has a mirror gloss and there are no polishing marks when observed under an optical microscope.

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