CN113186589B - Electrochemical surface treatment method for selectively laser melting AlSi10Mg alloy heat treatment product - Google Patents

Abstract

An electrochemical surface treatment method for selective laser melting AlSi10Mg alloy heat treatment products, the invention relates to the field of electrochemical surface finishing of metal materials. The invention aims to solve the technical problems of large surface roughness and low precision of existing selective laser melting AlSi10Mg alloy heat treatment products. Methods: The electrolyte was prepared with NaOH and EDTA; the AlSi10Mg alloy was polished and pickled; the three-electrode system was used for electrochemical polishing. The invention reduces the roughness of selective laser melting AlSi10Mg alloy heat-treated products from 12±2 μm to 3±2 μm by electrochemical surface treatment technology, and obtains AlSi10Mg alloy heat-treated samples with smooth surface and metallic luster. The invention is used for surface treatment of AlSi10Mg alloy heat treatment products.

Description

Electrochemical surface of a selective laser melting AlSi10Mg alloy heat-treated product Approach

technical field

The invention relates to the field of electrochemical surface finishing of metal materials.

Background technique

Metal material additive manufacturing technology, also known as 3D printing technology, laser rapid prototyping technology, 3D printing technology is an emerging and rapidly developing rapid prototyping manufacturing technology, widely used in the manufacture of modern models, The outstanding advantages of molds and parts are that no or less machining or molds are required, and parts with complex structures and shapes can be directly generated from computer graphics data, which can significantly shorten the product development cycle and improve the utilization efficiency and production efficiency of raw materials. reduce manufacturing cost.

As a new aluminum alloy forming technology, selective laser melting technology is not only suitable for preparing various parts with complex structures, but also has its unique characteristics in the forming process. Due to the small molten pool formed by the laser during the laser melting process, the cooling rate of the sample is very fast, which is conducive to obtaining a fine solidified structure, and will also cause some solute elements to dissolve into the aluminum matrix. However, due to the technical characteristics (powder, molten pool, etc.) of the AlSi _l0 Mg alloy manufactured by additives, the surface roughness of the laser additive manufacturing structure is relatively large, which is difficult to meet the use requirements of higher precision. Need to cooperate with subsequent surface finishing measures: deburring, mechanical polishing, chemical/electrochemical polishing, etc. to improve. Therefore, the post-processing of materials produced by additive manufacturing is crucial.

Contents of the invention

The invention aims to solve the technical problems of large surface roughness and low precision of existing selective laser melting AlSi10Mg alloy heat treatment products, and provides an electrochemical surface treatment method for selective laser melting AlSi10Mg alloy heat treatment products.

A kind of electrochemical surface treatment method of selective laser melting AlSi10Mg alloy heat treatment product, specifically carry out according to the following steps:

1. Use NaOH, EDTA and deionized water to prepare electrolyte, control the dosage of NaOH to 60-70g/L, and the dosage of EDTA to 15-20g/L;

2. Grind AlSi10Mg alloy, then pickle with pickling solution, rinse with running water immediately after pickling, and dry;

3. The AlSi10Mg alloy treated in step 2 is electrochemically polished using a three-electrode system, the platinum sheet is used as the cathode, the AlSi10Mg alloy is used as the anode, the Ag/AgCl electrode is used as the reference electrode, and the electrolyte is prepared in step 1; rinse with running water immediately after polishing;

4. Ultrasonic cleaning the AlSi10Mg alloy treated in step 3 to complete the electrochemical surface treatment method.

Further, step 1 controls the amount of NaOH to be 60g/L, and the amount of EDTA to be 16.7g/L.

Further, the mass percent content of elements in the AlSi10Mg alloy described in Step 2 is: Si: 10-11%, Mg: 0.2-0.3%, Fe: <0.05%, Cu: ≤0.01%, Ni: ≤0.01%, Zn : ≤0.01%, Ti: ≤0.02%, and the balance is aluminum. AlSi10Mg alloy was prepared by selective laser melting technology.

Further, step 2 is polished with 600-grit sandpaper. The oxide layer formed by laser melting is removed.

Further, the volume ratio of HNO ₃ , HF and H ₂ O in the pickling solution in step 2 is 10:3:7.

Further, the pickling time in the second step is 1-2 minutes, and the temperature is room temperature. Wash until the surface of the sample turns white.

Further, in the third step, the electrochemical polishing is performed under the condition of magnetic stirring, and the rotational speed of the magnetic constant temperature stirrer is controlled to be 3-4 r/s, and the temperature is 38-43°C.

Further, step 3 first soaks the AlSi10Mg alloy for 2-5 seconds, and then performs electrochemical polishing.

Further, for the electrochemical polishing described in Step 3, the electrochemical workstation adopts LSV mode, the control voltage is 0-10V, the scan rate is 0.05V/s, and the sensitivity is 1×10 ^-1 .

Further, ultrasonic cleaning as described in Step 4, the frequency is 40KHz, and the time is 5min.

The beneficial effects of the present invention are:

After the heat treatment of the AlSi10Mg aluminum alloy formed by SLM in the present invention, the size of the eutectic silicon increases and the distribution in the aluminum matrix is more uniform. During the heat treatment process, the eutectic silicon in the SLM-formed AlSi10M alloy undergoes a process of fracture from fibrous to massive, rounded, and grown in sequence, and finally presents a near-spherical morphology. Compared with before heat treatment, the tensile strength and yield strength of the alloy decreased, but the elongation increased, and the mechanical properties reached Rm≥380MPa, A≥8%. By performing certain electrochemical surface treatment on AlSi10Mg alloy heat treatment samples prepared by selective laser melting technology, high surface finish can be obtained; high polishing precision can be obtained; and the operating environment is good, metal loss is small, energy consumption is small; polishing speed It has nothing to do with the physical-mechanical properties of the metal, and can greatly improve production efficiency; it can improve the physical-mechanical properties, physicochemical properties and performance of the surface of metal parts; it is easier to master the operation technology.

The invention is used for surface treatment of AlSi10Mg alloy heat treatment products.

Description of drawings

Fig. 1 is the Tafel corrosion resistance test figure before and after the electrochemical surface treatment of AlSi10Mg alloy of embodiment one, wherein 1 represents before processing, and 2 represents after processing;

Fig. 2 is the XRD grazing incidence characterization pattern before and after the electrochemical surface treatment of AlSi10Mg alloy of embodiment one, wherein 1 represents before processing, and 2 represents after processing,

Fig. 3 is the electron micrograph before the electrochemical surface treatment of AlSi10Mg alloy of embodiment one,

Fig. 4 is the electron micrograph (1 μm) after the electrochemical surface treatment of AlSi10Mg alloy of embodiment one,

Fig. 5 is the electron micrograph (10 μm) after the electrochemical surface treatment of AlSi10Mg alloy of embodiment one,

Fig. 6 is the roughness curve figure after the electrochemical surface treatment of AlSi10Mg alloy of embodiment one,

Fig. 7 is the EDS test figure before the electrochemical surface treatment of AlSi10Mg alloy of embodiment one,

Fig. 8 is an EDS test chart of AlSi10Mg alloy after electrochemical surface treatment in Example 1.

detailed description

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Specific embodiment one: This embodiment is an electrochemical surface treatment method for selective laser melting AlSi10Mg alloy heat treatment products, which is characterized in that the method is specifically carried out according to the following steps:

1. Use NaOH, EDTA and deionized water to prepare electrolyte, control the dosage of NaOH to 60-70g/L, and the dosage of EDTA to 15-20g/L;

2. Grind AlSi10Mg alloy, then pickle with pickling solution, rinse with running water immediately after pickling, and dry;

3. The AlSi10Mg alloy treated in step 2 is electrochemically polished using a three-electrode system, the platinum sheet is used as the cathode, the AlSi10Mg alloy is used as the anode, the Ag/AgCl electrode is used as the reference electrode, and the electrolyte is prepared in step 1; rinse with running water immediately after polishing;

4. Ultrasonic cleaning the AlSi10Mg alloy treated in step 3 to complete the electrochemical surface treatment method.

Embodiment 2: This embodiment is different from Embodiment 1 in that: Step 1 controls the amount of NaOH to be 60 g/L, and the amount of EDTA to be 16.7 g/L. Others are the same as in the first embodiment.

Specific embodiment 3: The difference between this embodiment and specific embodiment 1 or 2 is that the mass percent content of elements in the AlSi10Mg alloy described in step 2 is: Si: 10-11%, Mg: 0.2-0.3%, Fe: < 0.05%, Cu: ≤0.01%, Ni: ≤0.01%, Zn: ≤0.01%, Ti: ≤0.02%, and the balance is aluminum. Others are the same as in the first or second embodiment.

Embodiment 4: This embodiment is different from Embodiment 1 to Embodiment 3 in that: Step 2 uses 600-grit sandpaper to polish. Others are the same as those in the first to third specific embodiments.

Embodiment 5: This embodiment differs from Embodiments 1 to 4 in that the volume ratio of HNO ₃ , HF and H ₂ O in the pickling solution in Step 2 is 10:3:7. Others are the same as one of the specific embodiments 1 to 4.

Embodiment 6: This embodiment differs from Embodiments 1 to 5 in that: Step 2 pickling time is 1-2 minutes, and the temperature is room temperature. Others are the same as one of the specific embodiments 1 to 5.

Embodiment 7: The difference between this embodiment and one of Embodiments 1 to 6 is that step 3 performs electrochemical polishing under the condition of magnetic stirring, and the rotational speed of the magnetic constant temperature stirrer is controlled to be 3 to 4 r/s, and the temperature is 38 to 43 ℃. Others are the same as one of the specific embodiments 1 to 6.

Embodiment 8: This embodiment differs from Embodiments 1 to 7 in that: step 3 first soaks the AlSi10Mg alloy for 2-5 seconds, and then performs electrochemical polishing. Others are the same as one of the specific embodiments 1 to 7.

Embodiment 9: This embodiment is different from Embodiment 1 to Embodiment 8 in that: the electrochemical polishing described in step 3, the electrochemical workstation adopts LSV mode, the control voltage is 0-10V, and the scanning speed is 0.05V/s. The sensitivity is 1×10 ^-1 . Others are the same as one of the specific embodiments 1 to 8.

Embodiment 10: This embodiment is different from Embodiment 1 to Embodiment 9 in that: the ultrasonic cleaning described in Step 4 has a frequency of 40 KHz and a time of 5 minutes. Others are the same as one of the specific embodiments 1 to 9.

Adopt the following examples to verify the beneficial effects of the present invention:

Embodiment one:

In this embodiment, an electrochemical surface treatment method for selective laser melting AlSi10Mg alloy heat treatment products is carried out according to the following steps:

1. Use NaOH, EDTA and deionized water to prepare electrolyte, control the dosage of NaOH to 60g/L, and the dosage of EDTA to 16.7g/L;

2. Grind the AlSi10Mg alloy, then pickle it with pickling solution, rinse it with running water immediately after pickling, and dry it;

3. The AlSi10Mg alloy treated in step 2 is electrochemically polished using a three-electrode system, the platinum sheet is used as the cathode, the AlSi10Mg alloy is used as the anode, the Ag/AgCl electrode is used as the reference electrode, and the electrolyte is prepared in step 1; rinse with running water immediately after polishing;

4. Ultrasonic cleaning the AlSi10Mg alloy treated in step 3 to complete the electrochemical surface treatment method.

The mass percent content of elements in the AlSi10Mg alloy described in step 2 is: Si: 10-11%, Mg: 0.2-0.3%, Fe: <0.05%, Cu: ≤0.01%, Ni: ≤0.01%, Zn: ≤0.01 %, Ti: ≤0.02% and the balance is aluminum.

Step 2 Sand with 600-grit sandpaper. The oxide layer formed by laser melting is removed.

The volume ratio of HNO ₃ , HF and H ₂ O in the pickling solution in step 2 is 10:3:7.

The pickling time in step 2 is 1-2 minutes, and the temperature is room temperature. Wash until the surface of the sample turns white.

Step 3 Electrochemical polishing is carried out under the condition of magnetic stirring, and the rotational speed of the magnetic constant temperature stirrer is controlled to 3r/s, and the temperature is 40°C

Step 3: Soak the AlSi10Mg alloy for 2-5 seconds, and then perform electrochemical polishing.

For the electrochemical polishing described in Step 3, the electrochemical workstation adopts LSV mode, the control voltage is 0-10V, the scan rate is 0.05V/s, and the sensitivity is 1×10 ^-1 .

Ultrasonic cleaning as described in Step 4, the frequency is 40KHz, and the time is 5min.

Figure 1 is the Tafel corrosion resistance test diagram of the AlSi10Mg alloy before and after electrochemical surface treatment in Example 1, where 1 represents before treatment and 2 represents after treatment; the comparison shows that the corrosion potential of the polished sample increases and the corrosion resistance performance increases.

Figure 2 is the XRD grazing incidence characterization pattern of AlSi10Mg alloy before and after electrochemical surface treatment in Example 1, where 1 represents before treatment, 2 represents after treatment, no new film layer is formed on the surface of the sample before and after polishing, all are Al _3.21 Si _0.47 mixture .

FIG. 3 is an electron micrograph of an AlSi10Mg alloy before electrochemical surface treatment in Example 1, and the surface is chaotic and rough.

Fig. 4 is the electron micrograph (1 μm) after the electrochemical surface treatment of the AlSi10Mg alloy of embodiment one, and Fig. 5 is the electron micrograph (10 μm) after the electrochemical surface treatment of the AlSi10Mg alloy of the embodiment one, it can be seen that melting appears on the surface after the treatment The pool phenomenon, the protrusions are evenly distributed, and the roughness is reduced.

Fig. 6 is a graph of the roughness after electrochemical surface treatment of AlSi10Mg alloy in Example 1, the roughness Ra=1.462 μm, and the surface is a sample with metallic luster of the matrix.

Figure 7 is the EDS test image of the AlSi10Mg alloy before electrochemical surface treatment in Example 1. The surface of the sample is mainly composed of three elements: Al, Si, and Mg. In the AlSi10Mg workpiece, the α-Al phase is wrapped by an appropriate amount of eutectic single crystal silicon , so the three elements distribution of Al, Si and O on the surface are basically the same; due to subsequent manufacturing process problems, more impurity Fe elements were introduced on the surface of this batch of samples.

Fig. 8 is an EDS test chart after the electrochemical surface treatment of the AlSi10Mg alloy in Example 1. The aluminum oxide phase on the surface of the sample is electrolytically reacted into an aluminum-silicon alloy, and the surface impurity Fe element is removed.

Claims (9)

1. An electrochemical surface treatment method for selectively melting AlSi10Mg alloy heat treatment products by laser is characterized by comprising the following steps:

1. preparing electrolyte by adopting NaOH, EDTA and deionized water, and controlling the dosage of the NaOH to be 60-70 g/L and the dosage of the EDTA to be 15-20 g/L;

2. polishing the AlSi10Mg alloy, then carrying out acid pickling by adopting a pickling solution, immediately washing with running water after acid pickling, and drying;

3. performing electrochemical polishing on the AlSi10Mg alloy treated in the step two by adopting a three-electrode system, wherein a platinum sheet is used as a cathode, the AlSi10Mg alloy is used as an anode, an Ag/AgCl electrode is used as a reference electrode, and an electrolyte is prepared in the step one; immediately flushing with running water after polishing;

4. carrying out ultrasonic cleaning on the AlSi10Mg alloy treated in the step three to finish the electrochemical surface treatment method;

step three, performing electrochemical polishing, wherein an electrochemical workstation adopts an LSV mode, and the control voltage is0-10V, sweep speed of 0.05V/s, and sensitivity of 1 × 10 ^-1 。

2. The method for electrochemically treating a surface of a selectively laser-melted AlSi10Mg alloy heat-treated article according to claim 1, wherein in the first step, the amount of NaOH is controlled to be 60g/L and the amount of EDTA is controlled to be 16.7g/L.

3. The electrochemical surface treatment method for selectively laser melting AlSi10Mg alloy heat-treated products according to claim 1, wherein the AlSi10Mg alloy in the second step comprises the following elements in percentage by mass: si:10 to 11%, mg:0.2 to 0.3%, fe: < 0.05%, cu: less than or equal to 0.01 percent, ni: less than or equal to 0.01 percent, zn: less than or equal to 0.01 percent, ti: less than or equal to 0.02 percent and the balance of aluminum.

4. The method for electrochemically treating a surface of a heat-treated product of a selective laser melting AlSi10Mg alloy according to claim 1, wherein in the second step, 600-mesh sanding is adopted.

5. The method as claimed in claim 1, wherein step two is carried out by using HNO in pickling solution ₃ HF and H ₂ The volume ratio of O is 10: 3: 7.

6. The electrochemical surface treatment method for the selective laser melting AlSi10Mg alloy heat treatment product according to claim 1, characterized in that the acid washing time of the step is 1-2 min, and the temperature is room temperature.

7. The electrochemical surface treatment method for the selective laser melting AlSi10Mg alloy heat treatment product according to claim 1, characterized in that step three is electrochemical polishing under the condition of magnetic stirring, the rotating speed of the magnetic constant temperature stirrer is controlled to be 3-4 r/s, and the temperature is controlled to be 38-43 ℃.

8. The electrochemical surface treatment method for the selective laser melting AlSi10Mg alloy heat treatment product according to claim 1, characterized in that in the third step, the AlSi10Mg alloy is soaked for 2-5 s and then is electrochemically polished.

9. The method as claimed in claim 1, wherein said ultrasonic cleaning is carried out at 40KHz for 5min.

Images