High-corrosion-resistance magnesium alloy component manufactured through electric arc additive and preparation method and application of high-corrosion-resistance magnesium alloy component

Abstract

The invention provides an electric arc additive manufacturing high-corrosion-resistance magnesium alloy component and a preparation method and application thereof.The preparation method of the electric arc additive manufacturing high-corrosion-resistance magnesium alloy component comprises the following steps that a magnesium alloy base plate is fixed to a workbench provided with a heating plate, and the heating plate is provided with a thermocouple; the thermocouple is connected with the temperature control box to control the temperature of the heating plate so as to realize constant-temperature heating of the magnesium alloy substrate; and the magnesium alloy wire is fixed to wire feeding equipment, single-channel layer-by-layer reciprocating deposition is carried out along the set track according to the set welding machine technological parameters till the target height is reached, and the high-corrosion-resistance magnesium alloy component is obtained. According to the method, the temperature of the magnesium alloy substrate and the interlayer temperature are controlled at a constant temperature through the external temperature field, the manufacturing process parameters are adjusted, the interlayer binding force and the forming quality of the magnesium alloy component are improved, and the prepared high-corrosion-resistance magnesium alloy is small in grain size and uniform in precipitated phase distribution and shows excellent corrosion resistance compared with a traditional cast magnesium alloy.

Description

Technical Field

[0001] The present invention relates to arc additive manufacturing technology, and in particular to an arc additive manufacturing high corrosion resistant magnesium alloy component, a preparation method and use thereof. Background Art

[0002] Among the existing engineering application metals, magnesium alloy is one of the lightest structural metal materials, with a density of only 1.7-1.8g / cm 3 , which is 1 / 4 of steel, 1 / 3 of titanium and 2 / 3 of aluminum. Magnesium alloy has the advantages of high specific strength, large elastic modulus, fast heat dissipation, good shock absorption and strong electromagnetic shielding, and has broad application prospects in the fields of automobiles, rail transportation, aerospace and medical care. At present, the preparation of most magnesium alloy components is often based on traditional casting processes. Due to the low cooling rate, the grain size of magnesium alloy components is coarse, and the precipitation phase is agglomerated in large particles. At the same time, magnesium itself has active chemical properties and its corrosion potential is extremely low compared to other elements (-2.37V / SHE). The widespread existence of galvanic corrosion causes the corrosion resistance of magnesium alloy components to be poor. In addition, the traditional magnesium alloy preparation process is complicated and the material utilization rate is low, making it difficult to prepare alloy parts of complex shapes. Therefore, the poor corrosion resistance and the constraints of the preparation process have greatly restricted the application and development of magnesium alloy components.

[0003] Arc additive manufacturing technology uses arc as heat source and wire as raw material. Under the guidance of digital model, the three-dimensional model of the part is layered with the help of slicing software, and the direct manufacturing of the component is achieved through "point-line-surface" layer-by-layer stacking. Different from the traditional casting process, arc additive manufacturing technology is a step-by-step stacking molding method from bottom to top according to a preset path, which can convert the shape of three-dimensional parts into two-dimensional shapes, thereby realizing the preparation of special complex structural parts. However, due to the low density of magnesium alloy melt, the buoyancy of bubbles involved in the additive process is small, and they cannot overflow from the melt in time, resulting in more pore defects in magnesium alloy components. When the components are in service under extreme conditions, once they are corroded by corrosive media, these pore defects often act as corrosion points, causing the corrosive media to gradually expand deep into the tissue. In particular, when the corrosive medium contains chloride ions, the generated loose product film will be decomposed by chloride ions to generate soluble chlorides, which cannot protect the alloy matrix like the aluminum alloy product film. At this time, the pore defects often act as corrosion extension channels, allowing chloride ions to continue to corrode the alloy matrix, thereby causing the rapid failure of magnesium alloy load-bearing components.

[0004] Although the literature shows that grain refinement can greatly improve the corrosion resistance of alloys, the presence of pore defects will greatly weaken the improvement of corrosion resistance by grain refinement. More pore defects are the key to the poor corrosion resistance of additively manufactured magnesium alloy components. Therefore, developing a preparation method for arc additive manufacturing of highly corrosion-resistant magnesium alloys is the key to solving the problem of the widespread application of magnesium alloy components in the product field. Summary of the invention

[0005] The purpose of the present invention is to propose a method for preparing high-corrosion-resistant magnesium alloy components by arc additive manufacturing, in response to the problems of many porosity defects and poor corrosion resistance in the current magnesium alloys manufactured by arc additive manufacturing. The method controls the temperature of the magnesium alloy substrate and the interlayer temperature by applying an external temperature field, and adjusts the manufacturing process parameters, thereby improving the interlayer bonding strength and forming quality of the magnesium alloy components. The prepared high-corrosion-resistant magnesium alloy has a fine grain size and a uniform distribution of precipitated phases, and exhibits excellent corrosion resistance compared to traditional cast magnesium alloys.

[0006] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing a high corrosion-resistant magnesium alloy component by arc additive manufacturing, comprising the following steps:

[0008] A magnesium alloy substrate is fixed on a workbench provided with a heating plate, a thermocouple is provided on the heating plate, and the thermocouple is connected to a temperature control box to control the temperature of the heating plate, thereby realizing constant temperature heating of the magnesium alloy substrate; a magnesium alloy wire is fixed on a wire feeding device, and a single-pass layer-by-layer reciprocating deposition is performed along a set trajectory according to the set welding machine process parameters to a target height, thereby obtaining a high corrosion-resistant magnesium alloy component.

[0009] Furthermore, the magnesium alloy substrate is pretreated before preparation: the surface is polished with sandpaper, the surface is ultrasonically cleaned with alcohol, and the surface is dried with cold air from a hair dryer to obtain a magnesium alloy substrate with a clean surface.

[0010] Furthermore, an additive experimental platform was built, a heating plate was placed on a workbench, a magnesium alloy substrate was placed flat on the heating plate, the temperature of the heating plate was controlled by connecting a temperature control box through a thermocouple, and the heating plate was turned on before the first layer of deposition to achieve constant temperature heating of the magnesium alloy substrate; the magnesium alloy wire was fixed on the wire feeding equipment, straightened by the wire feeder and sent to the bottom of the welding gun, with a dry extension of 5-15mm, and the angle of the welding gun was adjusted to be parallel to the normal direction of the substrate; the size of the magnesium alloy additive component was drawn with 3D modeling software, and the file was saved in the additive software of the welding gun robot arm to automatically generate a deposition trajectory, and the set program was input into the welding gun robot arm system; under the magnesium alloy additive process, according to the set welding machine process parameters, under a protective atmosphere, a cold metal transition welding heat source was used to perform single-pass layer-by-layer reciprocating deposition along the preset trajectory to finally obtain a highly corrosion-resistant magnesium alloy component.

[0011] Furthermore, the magnesium alloy substrate is an AZ series magnesium alloy rolled plate.

[0012] Furthermore, the magnesium alloy wire comprises the following components and their mass percentages: Al 3-9%, Zn 0.5-1%, Mn 0.1-0.5%, and the remainder is Mg and inevitable impurity elements. Unless otherwise specified, % in the present invention refers to mass percentage.

[0013] Furthermore, the diameter of the magnesium alloy wire is 1.0-2.0 mm.

[0014] Furthermore, the heating plate is a cast aluminum heating plate.

[0015] Furthermore, the cast aluminum heating plate is a 6061 aluminum alloy heating plate, a 6055 aluminum alloy heating plate or a 6063 aluminum alloy heating plate.

[0016] Furthermore, the temperature control box controls the temperature of the heating plate to be 200-300°C.

[0017] Furthermore, the constant temperature heating temperature of the magnesium alloy substrate is 100-150°C.

[0018] Furthermore, the process parameters of the welding machine are as follows: the current is 100-150A, the voltage is 10-15V; and / or the deposition speed is 8-12mm / s; and / or the wire feeding speed is 150-200mm / s.

[0019] Furthermore, the welding gun has an inter-layer upward lifting height of 2-4 mm.

[0020] Furthermore, the single layer height of the magnesium alloy component is 2-4 mm.

[0021] Furthermore, when single-pass layer-by-layer reciprocating deposition is performed along a preset track, the oxide film on the surface of the printed part is cleaned after each layer is deposited and the next layer is deposited after the interlayer temperature reaches 100-120° C. The interlayer temperature is measured by a thermocouple.

[0022] Furthermore, after each layer of deposition is completed, an angle grinder is used to clean the oxide film on the surface of the printed part.

[0023] Furthermore, the protective atmosphere during the reciprocating deposition process is high-purity argon gas, and the gas flow rate is 20 to 30 L / min.

[0024] Another object of the present invention is to disclose an arc additively manufactured high corrosion-resistant magnesium alloy component, which is prepared using the above method.

[0025] Furthermore, the highly corrosion-resistant magnesium alloy components include but are not limited to arc additively manufactured magnesium alloy straight wall components.

[0026] Furthermore, the arc additively manufactured magnesium alloy straight wall component has a length of 130 to 160 mm, a width of 6 to 10 mm, and a height of 60 to 90 mm.

[0027] Another object of the present invention is to disclose an arc additively manufactured high corrosion-resistant magnesium alloy component for use in the automotive, rail transportation, aerospace and medical fields.

[0028] The arc additive manufacturing method of the present invention uses wire with Mg-Al-Zn-Mn as the main alloying element as the raw material, and based on the cold metal transition welding arc additive manufacturing process, reciprocates layer by layer on the substrate according to a preset trajectory until the last layer is deposited, thereby obtaining a high corrosion resistant magnesium alloy component. Compared with the prior art, it has the following advantages:

[0029] 1) The present invention controls the temperature of the cast aluminum heating plate through a thermocouple and a temperature control box to achieve constant temperature heating of the magnesium alloy substrate, reducing the rapid diffusion of the temperature of the magnesium alloy melt within the solidification range, effectively solving the problems of excessive interlayer thickness and more pore defects caused by insufficient melt fluidity during the additive process, and improving the interlayer bonding strength and forming quality of the magnesium alloy component.

[0030] 2) The present invention rationally optimizes the arc additive manufacturing process parameters, and the microstructure of the prepared magnesium alloy component is composed of dispersed fine Al-Mn phases, which effectively alleviates the serious pitting corrosion of the magnesium matrix and is more prone to uniform corrosion in the corrosive medium. 17 Al 12 The second phase can effectively reduce the micro-galvanic corrosion effect, and more Al elements are dissolved in the magnesium matrix to reduce the potential difference between the second phase and the magnesium matrix, thereby reducing the corrosion tendency of the alloy component. On the other hand, the high corrosion-resistant magnesium alloy component of the present invention has a fine grain size, which can serve as a corrosion barrier to hinder the directional movement of electrons from the negative electrode to the positive electrode during micro-galvanic corrosion, thereby effectively reducing the corrosion current density and reducing the corrosion rate.

[0031] In summary, the present invention realizes preheating, temperature control, and material addition simultaneously by constantly controlling the temperature of the magnesium alloy substrate and the deposited layer, thereby avoiding the structural instability between different layer heights, and obtaining a magnesium alloy component with fine grain size and uniform distribution of precipitated phase. The component corrodes quite uniformly under long-term immersion and exhibits excellent corrosion resistance compared to traditional cast magnesium alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The metallographic structure of the high corrosion-resistant magnesium alloy component of Example 1;

[0033] Figure 2 The SEM microstructure of the high corrosion-resistant magnesium alloy component of Example 1;

[0034] Figure 3 The potentiodynamic polarization curves of the high corrosion-resistant magnesium alloy component of Example 1 and the comparative magnesium alloy component in 3.5% NaCl solution;

[0035] Figure 4 Bode diagram of the AC impedance spectrum of the high corrosion-resistant magnesium alloy component of Example 1 and the comparative example magnesium alloy component in 3.5% NaCl solution. DETAILED DESCRIPTION

[0036] The present invention is further described below with reference to the examples. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0037] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0038] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0039] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0040] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0041] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0042] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0043] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0044] Example 1

[0045] This embodiment discloses a highly corrosion-resistant magnesium alloy component, wherein a Mg-Al-Zn-Mn magnesium alloy wire with a diameter of 1.2 mm is selected for arc additive manufacturing of a magnesium alloy component by layer-by-layer reciprocating deposition, and the magnesium alloy wire composition is: 3.5% Al, 0.55% Zn, 0.32% Mn, and the rest is Mg and unavoidable impurity elements. The specific steps are as follows:

[0046] 1. Before the magnesium alloy arc additive manufacturing, the magnesium alloy substrate needs to be pretreated. The magnesium alloy substrate is an AZ31B series magnesium alloy rolled plate with a size of 200mm×200mm×20mm. After the surface is polished with 400-mesh sandpaper, the substrate is ultrasonically cleaned with alcohol for 10 minutes, and then dried with cold air from a hair dryer to obtain a magnesium alloy additive substrate with a clean surface.

[0047] 2. Place a 6061 cast aluminum heating plate on the workbench with a size of 250mm×250mm×20mm. Place the component substrate flat on the heating plate and fix it. Connect the temperature control box through a thermocouple to control the temperature of the heating plate to 250℃ and the substrate to a constant temperature of 130℃.

[0048] 3. Use SolidWorks software to pre-process the 3D model of the target structural part and generate an additive model. Use additive processing software to slice the model in layers, with a layer height of 2.5mm. Set the arc to start along one side of the substrate, and close the arc after a single layer is deposited to 150mm. The second layer starts the arc at the arc closing position of the upper layer, and closes the arc at the arc starting position. Deposit 32 layers layer by layer, and the final structure is preset to a height of 80mm. Import the planned additive path into the robot control system.

[0049] 4. Fix the magnesium alloy wire on the wire feeding device, straighten it through the wire feeder and send it to the bottom of the robotic arm welding gun, with a dry extension of 8mm. The controller sets the welding gun arc starting point on the substrate according to the additive path, and adjusts the welding gun angle to be parallel to the normal direction of the substrate.

[0050] 5. The robot arm controls the additive arc to execute the preset additive instructions according to the additive path under the protection of argon gas, with a gas flow rate of 25L / min. Use an angle grinder to remove the interlayer oxide film and burn damage and use a thermocouple to measure the temperature. The interlayer temperature is controlled at 100°C. Select the cold metal transition welding mode, current 115A, voltage 11.5V, wire feeding speed 155.2mm / s, deposition speed 10mm / s, layer by layer reciprocating deposition 32 layers, the single layer height of the component is 2.5mm, and finally obtain the arc additive manufacturing AZ magnesium alloy component with an actual size of 152mm×8.2mm×82.5mm.

[0051] Example 2

[0052] This embodiment discloses a highly corrosion-resistant magnesium alloy component, wherein a Mg-Al-Zn-Mn magnesium alloy wire with a diameter of 1.2 mm is selected for arc additive manufacturing of a magnesium alloy component by layer-by-layer reciprocating deposition, and the magnesium alloy wire composition is: 3.5% Al, 0.55% Zn, 0.32% Mn, and the rest is Mg and unavoidable impurity elements. The specific steps are as follows:

[0053] 1. Before the magnesium alloy arc additive manufacturing, the magnesium alloy substrate needs to be pretreated. The magnesium alloy substrate is an AZ31B magnesium alloy rolled plate with a size of 200mm×200mm×20mm. After the surface is polished with 400-grit sandpaper, the substrate is ultrasonically cleaned with alcohol for 10 minutes, and then dried with cold air from a hair dryer to obtain a magnesium alloy additive substrate with a clean surface.

[0054] 2. Place a 6061 cast aluminum heating plate on the workbench with a size of 250mm×250mm×20mm. Place the component substrate flat on the heating plate and fix it. Connect the temperature control box through a thermocouple to control the temperature of the heating plate to 265℃ and the substrate to a constant temperature of 140℃.

[0055] 3. Use SolidWorks software to pre-process the 3D model of the target structural part and generate an additive model. Use additive processing software to slice the model in layers, with a layer height of 2.8mm. Set the arc to start along one side of the substrate, and close the arc after a single layer is deposited to 150mm. The second layer starts the arc at the arc closing position of the upper layer, and closes the arc at the arc starting position. Deposit 30 layers layer by layer, and the final structural part has a preset height of 84mm. Import the planned additive path into the robotic arm control system.

[0056] 4. Fix the magnesium alloy wire on the wire feeding device, straighten it through the wire feeder and send it to the bottom of the robotic arm welding gun, with a dry extension of 10 mm. The controller sets the welding gun arc starting point on the substrate according to the additive path, and adjusts the welding gun angle to be parallel to the normal direction of the substrate.

[0057] 5. The robot arm controls the additive arc to execute the preset additive instructions according to the additive path under the protection of argon gas, with a gas flow rate of 25L / min. Use an angle grinder to remove the interlayer oxide film and burn damage and use a thermocouple to measure the temperature. The interlayer temperature is controlled at 100°C. Select the cold metal transition welding mode, current 130A, voltage 12.3V, wire feeding speed 158.7mm / s, deposition speed 10mm / s, layer by layer reciprocating deposition 30 layers, the single layer height of the component is 2.8mm, and finally obtain the arc additive manufacturing AZ magnesium alloy component with an actual size of 155mm×8.5mm×86.1mm.

[0058] Example 3

[0059] This embodiment discloses a highly corrosion-resistant magnesium alloy component, wherein a Mg-Al-Zn-Mn magnesium alloy wire with a diameter of 1.2 mm is selected for arc additive manufacturing of a magnesium alloy component by layer-by-layer reciprocating deposition, and the magnesium alloy wire composition is: 3.5% Al, 0.55% Zn, 0.32% Mn, and the rest is Mg and unavoidable impurity elements. The specific steps are as follows:

[0060] 1. Before the magnesium alloy arc additive manufacturing, the magnesium alloy substrate needs to be pretreated. The magnesium alloy substrate is an AZ31B magnesium alloy rolled plate with a size of 200mm×200mm×20mm. After the surface is polished with 400-grit sandpaper, the substrate is ultrasonically cleaned with alcohol for 10 minutes, and then dried with cold air from a hair dryer to obtain a magnesium alloy additive substrate with a clean surface.

[0061] 2. Place a 6061 cast aluminum heating plate on the workbench with a size of 250mm×250mm×20mm. Place the component substrate flat on the heating plate and fix it. Connect the temperature control box through a thermocouple to control the temperature of the heating plate to 265℃ and the substrate to a constant temperature of 140℃.

[0062] 3. Use SolidWorks software to pre-process the 3D model of the target structural part and generate an additive model. Use additive processing software to slice the model in layers, with a layer height of 2.8mm. Set the arc to start along one side of the substrate, and close the arc after a single layer is deposited to 150mm. The second layer starts the arc at the arc closing position of the upper layer, and closes the arc at the arc starting position. Deposit 30 layers layer by layer, and the final structural part has a preset height of 84mm. Import the planned additive path into the robotic arm control system.

[0063] 4. Fix the magnesium alloy wire on the wire feeding device, straighten it through the wire feeder and send it to the bottom of the robotic arm welding gun, with a dry extension of 10 mm. The controller sets the welding gun arc starting point on the substrate according to the additive path, and adjusts the welding gun angle to be parallel to the normal direction of the substrate.

[0064] 5. The robot arm controls the additive arc to execute the preset additive instructions according to the additive path under the protection of argon gas, with a gas flow rate of 25L / min. Use an angle grinder to remove the interlayer oxide film and burn damage and use a thermocouple to measure the temperature. The interlayer temperature is controlled at 100°C. Select the cold metal transition welding mode, current 145A, voltage 13.8V, wire feeding speed 165.8mm / s, deposition speed 10mm / s, layer by layer reciprocating deposition 30 layers, the single layer height of the component is 2.8mm, and finally obtain the arc additive manufacturing AZ magnesium alloy component with an actual size of 156.5mm×8.65mm×86.9mm.

[0065] Example 4

[0066] This embodiment discloses a highly corrosion-resistant magnesium alloy component, wherein a Mg-Al-Zn-Mn magnesium alloy wire with a diameter of 1.2 mm is selected for arc additive manufacturing of a magnesium alloy component by layer-by-layer reciprocating deposition, and the magnesium alloy wire composition is: 8.7% Al, 0.58% Zn, 0.25% Mn, and the rest is Mg and unavoidable impurity elements. The specific steps are as follows:

[0067] 1. Before the magnesium alloy arc additive manufacturing, the magnesium alloy substrate needs to be pretreated. The magnesium alloy substrate is an AZ91D series magnesium alloy rolled plate with a size of 200mm×200mm×20mm. After the surface is polished with 400-mesh sandpaper, the substrate is ultrasonically cleaned with alcohol for 10 minutes, and then dried with cold air from a hair dryer to obtain a magnesium alloy additive substrate with a clean surface.

[0068] 2. Place a 6061 cast aluminum heating plate on the workbench with a size of 250mm×250mm×20mm. Place the component substrate flat on the heating plate and fix it. Connect the temperature control box through a thermocouple to control the temperature of the heating plate to 265℃ and the substrate to a constant temperature of 140℃.

[0069] 3. Use SolidWorks software to pre-process the 3D model of the target structural part and generate an additive model. Use additive processing software to slice the model in layers, with a layer height of 2.8mm. Set the arc to start along one side of the substrate, and close the arc after a single layer is deposited to 150mm. The second layer starts the arc at the arc closing position of the upper layer, and closes the arc at the arc starting position. Deposit 30 layers layer by layer, and the final structural part has a preset height of 84mm. Import the planned additive path into the robotic arm control system.

[0070] 4. Fix the magnesium alloy wire on the wire feeding device, straighten it through the wire feeder and send it to the bottom of the robotic arm welding gun, with a dry extension of 10 mm. The controller sets the welding gun arc starting point on the substrate according to the additive path, and adjusts the welding gun angle to be parallel to the normal direction of the substrate.

[0071] 5. The robot arm controls the additive arc to execute the preset additive instructions according to the additive path under the protection of argon gas, with a gas flow rate of 25L / min. Use an angle grinder to remove the interlayer oxide film and burn damage and use a thermocouple to measure the temperature. The interlayer temperature is controlled at 100°C. Select the cold metal transition welding mode, current 125A, voltage 12V, wire feeding speed 156.5mm / s, deposition speed 8.5mm / s, layer by layer reciprocating deposition 30 layers, the single layer height of the component is 2.8mm, and finally obtain the arc additive manufacturing AZ magnesium alloy component with an actual size of 156mm×8.75mm×85.5mm.

[0072] Example 5

[0073] This embodiment discloses a highly corrosion-resistant magnesium alloy component, wherein a Mg-Al-Zn-Mn magnesium alloy wire with a diameter of 1.2 mm is selected for arc additive manufacturing of a magnesium alloy component by layer-by-layer reciprocating deposition, and the magnesium alloy wire composition is: 8.7% Al, 0.58% Zn, 0.25% Mn, and the rest is Mg and unavoidable impurity elements. The specific steps are as follows:

[0074] 1. Before the magnesium alloy arc additive manufacturing, the magnesium alloy substrate needs to be pretreated. The magnesium alloy substrate is an AZ91D series magnesium alloy rolled plate with a size of 200mm×200mm×20mm. After the surface is polished with 400-mesh sandpaper, the substrate is ultrasonically cleaned with alcohol for 10 minutes, and then dried with cold air from a hair dryer to obtain a magnesium alloy additive substrate with a clean surface.

[0075] 2. Place a 6061 cast aluminum heating plate on the workbench with a size of 250mm×250mm×20mm. Place the component substrate flat on the heating plate and fix it. Connect the temperature control box through a thermocouple to control the temperature of the heating plate to 270℃ and the substrate to a constant temperature of 140℃.

[0076] 3. Use SolidWorks software to pre-process the 3D model of the target structural part and generate an additive model. Use additive processing software to slice the model in layers, with a layer height of 3.0 mm. Set the arc to start along one side of the substrate, and close the arc after a single layer is deposited to 150 mm. The second layer starts the arc at the arc closing position of the upper layer, and closes the arc at the arc starting position. Deposit 28 layers layer by layer, and the final structure is preset to have a height of 84 mm. Import the planned additive path into the robot control system.

[0077] 4. Fix the magnesium alloy wire on the wire feeding device, straighten it through the wire feeder and send it to the bottom of the robotic arm welding gun, with a dry extension of 10 mm. The controller sets the welding gun arc starting point on the substrate according to the additive path, and adjusts the welding gun angle to be parallel to the normal direction of the substrate.

[0078] 5. The robot arm controls the additive arc to execute the preset additive instructions according to the additive path under the protection of argon gas, with a gas flow rate of 25L / min. Use an angle grinder to remove the interlayer oxide film and burn damage and use a thermocouple to measure the temperature. The interlayer temperature is controlled at 100°C. Select the cold metal transition welding mode, current 145A, voltage 13.8V, wire feeding speed 165.8mm / s, deposition speed 8.5mm / s, layer by layer reciprocating deposition 28 layers, the single layer height of the component is 3.0mm, and finally obtain the arc additive manufacturing AZ magnesium alloy component with an actual size of 155.8mm×8.78mm×86.8mm.

[0079] Comparative Example

[0080] This comparative example discloses a magnesium alloy component, wherein a Mg-Al-Zn-Mn magnesium alloy wire with a diameter of 1.2 mm is selected for arc additive manufacturing of a magnesium alloy component by layer-by-layer reciprocating deposition, and the wire composition is: 3.5% Al, 0.55% Zn, 0.32% Mn, and the rest is Mg and unavoidable impurity elements. The specific steps are as follows:

[0081] 1. Before the magnesium alloy arc additive manufacturing, the component substrate needs to be pretreated. The component substrate is an AZ31B magnesium alloy rolled plate with a size of 200mm×200mm×20mm. After the surface is polished with 400-grit sandpaper, the substrate is ultrasonically cleaned with alcohol for 10 minutes, and then dried with cold air from a hair dryer to obtain a magnesium alloy additive substrate with a clean surface.

[0082] 2. Place a 6061 cast aluminum heating plate on the workbench with a size of 250mm×250mm×20mm. Place the component substrate flat on the heating plate and fix it. Connect the temperature control box through a thermocouple to control the temperature of the heating plate to 120℃ and the substrate to a constant temperature of 70℃.

[0083] 3. Use SolidWorks software to pre-process the 3D model of the target structural part and generate an additive model. Use additive processing software to slice the model in layers, with a layer height of 2.5mm. Set the arc to start along one side of the substrate, and close the arc after a single layer is deposited to 150mm. The second layer starts the arc at the arc closing position of the upper layer, and closes the arc at the arc starting position. Deposit 32 layers layer by layer, and the final structure is preset to a height of 80mm. Import the planned additive path into the robot control system.

[0084] 4. Fix the magnesium alloy wire on the wire feeding device, straighten it through the wire feeder and send it to the bottom of the robotic arm welding gun, with a dry extension of 8mm. The controller sets the welding gun arc starting point on the substrate according to the additive path, and adjusts the welding gun angle to be parallel to the normal direction of the substrate.

[0085] 5. The robot arm controls the additive arc to execute the preset additive instructions according to the additive path under the protection of argon gas, with a gas flow rate of 25L / min. Use an angle grinder to remove the interlayer oxide film and burn damage. The interlayer temperature is not controlled and the interval time is 20s. Select the cold metal transition welding mode, current 95A, voltage 10.5V, wire feeding speed 133.3mm / s, deposition speed 6.67mm / s, layer by layer reciprocating deposition 32 layers, the single layer height of the component is 2.5mm, and finally obtain the arc additive manufacturing AZ magnesium alloy component with an actual size of 151.2mm×6.8mm×80.9mm.

[0086] The above embodiments and comparative examples are tested respectively below, and the test process and results are as follows:

[0087] The alloy samples were polished and the corrosion resistance of the magnesium alloy components prepared in the embodiment and the comparative example was tested at room temperature using a Coster electrochemical workstation, and the experimental medium was a 3.5wt.% sodium chloride solution. During the test, the working electrode was immersed in the solution, and the electrochemical experiment was performed after the open circuit real-time potential was stabilized. The corrosion current density and the impedance modulus value at a frequency of 0.01Hz are shown in Table 1.

[0088] Table 1 Test results of embodiments and comparative examples

[0089]

[0090] It can be seen from the test results that the corrosion current density of the polarization curve fitting of the high corrosion-resistant magnesium alloy components of Examples 1-5 is smaller than that of the comparative magnesium alloy components, and shows a lower corrosion rate in the NaCl corrosive medium. When the frequency is 0.01 Hz, the impedance modulus of the high corrosion-resistant magnesium alloy components of Examples 1-5 is much greater than that of the comparative magnesium alloy components, and the corrosion resistance is significantly better.

[0091] Figure 1 This is the metallographic structure of the high corrosion-resistant magnesium alloy component of Example 1, which shows that the high corrosion-resistant magnesium alloy has the characteristics of stable size distribution and fine grains. Figure 2 This is the SEM microstructure of the high corrosion-resistant magnesium alloy component of Example 1, which shows that the high corrosion-resistant magnesium alloy has uniform structure, fewer void defects, smaller precipitated phase size and is dispersed in the alloy matrix, which can effectively reduce the microgalvanic corrosion effect of the alloy and reduce the occurrence of pitting corrosion. Figure 3 The potentiodynamic polarization curves of the high corrosion-resistant magnesium alloy component of Example 1 and the comparative magnesium alloy component in 3.5% NaCl solution show that the magnesium alloy prepared by the process of the present invention has higher corrosion potential and better corrosion resistance. Figure 4 The Bode diagram of the AC impedance spectrum of the high corrosion-resistant magnesium alloy component of Example 1 and the comparative example magnesium alloy component in 3.5% NaCl solution shows that the high corrosion-resistant magnesium alloy component prepared by the process of the present invention has a significantly higher impedance modulus value at 0.01 Hz, a smaller pitting tendency and better corrosion resistance.

[0092] It can be seen that the high corrosion-resistant magnesium alloy prepared by the present invention has high corrosion resistance by optimizing additive manufacturing process parameters such as current, voltage, and deposition speed.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high corrosion-resistant magnesium alloy component by arc additive manufacturing, characterized in that: The following steps are involved: A magnesium alloy substrate is fixed on a workbench provided with a heating plate, a thermocouple is provided on the heating plate, and the thermocouple is connected to a temperature control box to control the temperature of the heating plate, thereby realizing constant temperature heating of the magnesium alloy substrate; a magnesium alloy wire is fixed on a wire feeding device, and a single-pass layer-by-layer reciprocating deposition is performed along a set trajectory according to the set welding machine process parameters to a target height, thereby obtaining a high corrosion-resistant magnesium alloy component.

2. The method for preparing a high corrosion-resistant magnesium alloy component by arc additive manufacturing according to claim 1, characterized in that: The magnesium alloy substrate was pretreated before preparation: the surface was polished with sandpaper, the surface was ultrasonically cleaned with alcohol, and the surface was dried with cold air from a hair dryer to obtain a magnesium alloy substrate with a clean surface.

3. The method for preparing a high corrosion-resistant magnesium alloy component by arc additive manufacturing according to claim 1, characterized in that: The magnesium alloy substrate is an AZ series magnesium alloy rolled plate; And / or, the magnesium alloy wire comprises the following components and their mass percentages: Al 3-9%, Zn 0.5-1%, Mn 0.1-0.5%, and the remainder is Mg and unavoidable impurity elements; And / or, the diameter of the magnesium alloy wire is 1.0-2.0 mm.

4. The method for preparing a high corrosion-resistant magnesium alloy component by arc additive manufacturing according to claim 1, characterized in that: The heating plate is a cast aluminum heating plate.

5. The method for preparing a high corrosion-resistant magnesium alloy component by arc additive manufacturing according to claim 1, characterized in that: The temperature control box controls the temperature of the heating plate to 200-300°C; And / or, the constant temperature heating temperature of the magnesium alloy substrate is 100-150°C.

6. The method for preparing a highly corrosion-resistant magnesium alloy component by arc additive manufacturing according to claim 1, characterized in that: The process parameters of the welding machine are as follows: the current is 100-150A, the voltage is 10-15V; And / or, the deposition speed is 8 to 12 mm / s; and / or, the wire feeding speed is 150 to 200 mm / s; And / or, the welding gun has an interlayer upward lifting height of 2-4 mm; And / or, the single layer height of the magnesium alloy component is 2-4 mm.

7. The method for preparing a high corrosion-resistant magnesium alloy component by arc additive manufacturing according to claim 1, characterized in that: When performing single-pass layer-by-layer reciprocating deposition along a preset trajectory, the oxide film on the surface of the printed part is cleaned after each layer is deposited, and the next layer is deposited after the interlayer temperature reaches 100-120°C.

8. The method for preparing a high corrosion-resistant magnesium alloy component by arc additive manufacturing according to claim 1, characterized in that: The protective atmosphere during the reciprocating deposition process is high-purity argon gas, and the gas flow rate is 20-30 L / min.

9. An arc additive manufacturing method for a high corrosion-resistant magnesium alloy component, characterized in that: The method is prepared by any one of claims 1 to 8.

10. Use of the arc additively manufactured high corrosion-resistant magnesium alloy component according to claim 9 in the fields of automobiles, rail transportation, aerospace and medical treatment.

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