Steel-aluminum dissimilar metal double-sided electric arc additive manufacturing intermetallic compound regulation and control method

Abstract

The invention discloses a steel-aluminum dissimilar metal double-sided electric arc additive manufacturing intermetallic compound regulation and control method, and belongs to the field of additive manufacturing. According to the method, a steel-aluminum explosive welding head is used as an intermediate medium, steel alloy surfacing is conducted on the steel side, and meanwhile aluminum alloy surfacing is conducted on the aluminum side; balance of temperature and stress of a steel-aluminum explosive welding interface is achieved by adjusting heat input and cooling rate, heat input is achieved by adjusting surfacing welding parameters on two sides, heat conduction is achieved by adjusting the thickness of a steel / aluminum explosive welding head, and the cooling rate is achieved by a gas-solid mixed CO2 welding chilling automatic adjusting device. Through multi-party cooperative regulation and control, it is guaranteed that the interface is within a temperature range, the temperature range is suitable for mutual diffusion of Fe and Al elements of the interface, too fast growth of IMC is avoided, and formation of a high-strength nanometer IMC diffusion bonding layer can be promoted. Therefore, not only is the structural stability of the steel / aluminum interface optimized, but also the problem of interface cracking caused by overlarge stress is avoided.

Description

Technical Field

[0001] The present invention belongs to the field of additive manufacturing, and specifically relates to a method for controlling intermetallic compounds in steel-aluminum dissimilar metal double-sided arc additive manufacturing. Background Art

[0002] In industrial applications, steel-aluminum dissimilar metal composite structures have important applications in lightweight structural design and efficient electrical conductivity due to their excellent mechanical properties and good corrosion resistance, such as the lower anode steel claw and upper aluminum guide rod structure commonly seen in the electrolytic aluminum industry. However, due to the differences in physical and chemical properties between steel and aluminum, it is very difficult to directly weld the two. Traditional steel / aluminum welding faces many challenges, especially the easy generation of a large number of intermetallic compounds (IMC) at the interface, which increases the interface brittleness and reduces the joint strength.

[0003] Compared with the traditional steel / aluminum welding process, the steel / aluminum additive manufacturing technology further aggravates the growth of IMC at the steel / aluminum interface and the increase of interface stress due to its repeated thermal cycles and high heat accumulation. In particular, with the increase in the number of deposited layers, the increase in thermal stress and intermetallic compound thickness will cause the steel / aluminum interface to spontaneously crack under excessive stress. The commonly used steel / aluminum explosive welding joint interface has no brittle IMC, but the metallurgical bonding strength of the interface is not strong enough, the Fe-Al mutual diffusion is limited, and explosive welding cannot achieve additive manufacturing. In order to achieve high-reliability additive manufacturing of steel / aluminum, it is necessary to control the interface to produce a thin nano-IMC layer, which cannot be achieved by existing methods, so a new process continues to be developed. Summary of the invention

[0004] The purpose of the present invention is to realize the additive manufacturing of steel-aluminum dissimilar double-sided metals, and effectively prevent the increase of the thickness of the intermetallic compound from causing the steel / aluminum interface to spontaneously crack under excessive stress.

[0005] The present invention provides a method for regulating intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing, comprising the following steps:

[0006] Step 1: Pre-treat the surfaces of the areas to be contacted between the steel plate and the aluminum alloy; perform explosion welding on the steel plate and the aluminum alloy to form a welded body, the top and bottom ends of the welded body are fixed by a first clamp and a second clamp; a first thermocouple and a first cooling device are installed at the top end of the welded body, and a second thermocouple and a second cooling device are installed at the bottom end; the steel plate is provided with a first MIG welding device, and a second MIG welding device is provided on the aluminum alloy side;

[0007] Step 2: Start the first MIG welding equipment, the second MIG welding equipment, the first thermocouple, and the second thermocouple at the same time, and weld the steel alloy on the steel plate side and the aluminum alloy on the aluminum alloy side; adjust the welding parameters to ensure the heat input balance on both sides, and adjust the first cooling device and the second cooling device to ensure the temperature of the weld body;

[0008] Step 3: After the surfacing is completed, turn off the first MIG welding device, the second MIG welding device, the first thermocouple, the second thermocouple, the first cooling device, and the second cooling device.

[0009] Furthermore, the top end and the bottom end of the welding body pass through the first clamp and the second clamp.

[0010] Furthermore, the first thermocouple installed at the top of the welding body is connected in sequence to the first CO2 gas flow regulating device of the first cooling device, the first cooling gas and the first CO2 welding rapid cooling device; the second thermocouple installed at the bottom of the welding body is connected in sequence to the second CO2 gas flow regulating device of the second cooling device, the second cooling gas and the second CO2 welding rapid cooling device.

[0011] Furthermore, the first CO2 rapid cooling device for welding blows vertically toward the explosion welding joint at the top end of the welding body, and the second CO2 rapid cooling device for welding blows vertically toward the explosion welding joint at the bottom end of the welding body.

[0012] Further, when the temperature detected by the first thermocouple and the second thermocouple exceeds 300°C, the first cooling device and the second cooling device are started, and the welding of the first MIG welding equipment and the second MIG welding equipment on both sides is stopped; when the temperature detected by the first thermocouple and the second thermocouple is lower than 300°C, the first cooling device and the second cooling device are stopped; when the temperature detected by the first thermocouple and the second thermocouple is lower than 200°C, the first MIG welding equipment and the second MIG welding equipment on both sides are started for welding (16).

[0013] Furthermore, the thickness of the aluminum alloy is 4 mm thicker than that of the steel plate; the thickness of the steel plate is 6 to 8 mm, and the thickness of the aluminum alloy is 10 to 12 mm.

[0014] Furthermore, the welding speed on the steel plate side is 250-350 mm / min, and the surfacing current I 铝 150~180A, voltage U 铝 It is 24~26V.

[0015] Furthermore, the welding speed on the aluminum alloy side is 250-350 mm / min, and the surfacing current I 钢 140~160A, voltage U 钢 It is 22~24V.

[0016] Furthermore, the total power P on the aluminum alloy side 铝 =U铝 I 铝 Not less than the total power P on the steel side 钢 =U 钢 I 钢 80% of.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention provides a device and method for regulating intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing, which significantly improves the welding quality and mechanical properties of steel / aluminum composite materials by controlling the interface temperature, stress and growth of intermetallic compounds (IMC).

[0019] 2. The present invention realizes the control of the interface IMC layer. By adjusting the heat input, cooling rate and thickness of the steel-aluminum explosion weld joint, the thin layer nano-control of the intermetallic compound at the steel / aluminum interface is successfully realized, avoiding the excessive growth of IMC and its negative impact on the joint strength. This technology can effectively promote the moderate diffusion of Fe and Al elements, form a high-strength nano-IMC diffusion bonding layer, and ensure the high-strength bonding of the steel / aluminum interface.

[0020] 3. The present invention uses the double-sided synchronous surfacing technology and the heat input balance effect to reduce the asymmetric thermal stress and thermal deformation caused by uneven thermal gradient at the steel / aluminum interface, and effectively reduces the interface stress concentration phenomenon. This not only optimizes the structural stability of the steel / aluminum interface, but also avoids the interface cracking problem caused by excessive stress.

[0021] 4. The present invention provides a temperature control method for CO2 rapid cooling during welding; rapid cooling during welding is a method for controlling the temperature during welding, which is different from the post-weld cooling method mentioned in previous patents and has higher timeliness of temperature control. At the same time, a gas-solid mixed CO2 rapid cooling device for welding is proposed. The ejection temperature of the gas-solid mixed CO2 is -78°C, which has higher cooling efficiency than the commonly used cold argon gas and cold air, and lower cost and higher safety than liquid nitrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a device for regulating intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing;

[0023] Figure 2 It is a crack-free and deformation-free aluminum / steel double-sided arc additive manufacturing component prepared by the method of the present invention;

[0024] Figure 3 This is a comparative example 1 in which an aluminum alloy arc additive manufacturing component is directly performed on the surface of a steel plate.

[0025] Among them, the figure markings are: 1-the first CO2 welding rapid cooling device, 2-the second CO2 welding rapid cooling device, 3-the first thermocouple, 4-the second thermocouple, 5-the first clamp for fixing high-strength steel, 6-the second clamp for fixing high-strength steel, 7-explosive welding transition joint steel plate, 8-explosive welding transition joint aluminum plate, 9-aluminum alloy surfacing layer, 10-steel surfacing layer, 11-arc 1, 12-arc 2, 13-steel welding wire, 14-aluminum welding wire, 15-the first MIG welding gun, 16-the second MIG welding gun, 17-the first wire feeder, 18-the second wire feeder, 19-steel molten droplet, 20-aluminum molten droplet, 21-the first cooling gas, 22-the second cooling gas, 23-the first CO2 gas flow regulating device, 24-the second CO2 gas flow regulating device. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings.

[0027] The present invention uses the steel-aluminum explosion welding joint as an intermediate medium, performs steel alloy surfacing on the steel side of the explosion welding joint, and simultaneously performs aluminum alloy surfacing on the aluminum side of the explosion welding joint, thereby avoiding direct melting of aluminum and steel. The balance of temperature and stress at the steel-aluminum explosion welding interface is achieved by adjusting the heat input and cooling rate, wherein the heat input is achieved by adjusting the surfacing welding parameters on both sides, the heat conduction is achieved by adjusting the thickness of the steel / aluminum explosion welding joint, and the cooling rate is achieved by a gas-solid mixed CO2 welding chilling automatic adjustment device. Through multi-party coordinated regulation, the interface is guaranteed to be within a temperature range of (200-300°C), which is suitable for the mutual diffusion of Fe and Al elements at the interface, which not only avoids the excessive growth of IMC, but also promotes the formation of a high-strength nano-IMC diffusion bonding layer.

[0028] Interface stress is another major problem of steel / aluminum cracking. Stress relief is achieved through synchronous surfacing on both sides, which utilizes the balancing effect of arc heat input on both sides: the temperature gradients formed by the heat input on the steel side and the aluminum side offset each other, reducing the asymmetric thermal stress and thermal deformation caused by the single-sided heat source on the explosive welding joint, which helps to improve the structural stability of the welding area. The application of the method of the present invention is expected to achieve high-strength steel / aluminum dissimilar metal additive manufacturing.

[0029] The present invention discloses a method for regulating intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing, comprising the following steps:

[0030] Step 1: Preparation before welding

[0031] Material selection and pretreatment: Select suitable steel (such as stainless steel, carbon steel, etc.) and aluminum alloy materials (such as aluminum 6061, aluminum 1050, etc.). Clean the contact surface of steel and aluminum to remove the oxide layer, oil stains and impurities. Use grinding wheels, mechanical grinding or chemical cleaning to ensure the cleanliness of the contact surface.

[0032] Production of steel / aluminum explosion welded joints: According to the design requirements, steel and aluminum materials are explosion welded to form a reliable metallurgical bond. The steel / aluminum interface of the explosion welded joint should have no obvious cracks or holes.

[0033] Welding equipment preparation: Configure arc welding equipment suitable for double-sided cladding, and select appropriate welding power supply, welding gun and welding track. Prepare the steel alloy and aluminum alloy welding wire required for cladding, and ensure the compatibility of the welding wire material with the base material. Check whether the cooling equipment used in the welding process (such as CO2 gas-solid mixed welding rapid cooling device) is operating normally to ensure the stability of the cooling system.

[0034] Step 2: Heat input control during welding

[0035] Heat input adjustment of welding arc: Steel side welding parameter setting: Select steel alloy welding wire, set welding current, welding voltage, welding speed. Aluminum side welding parameter setting: Select aluminum alloy welding wire, set welding current, welding voltage, welding speed.

[0036] Double-sided synchronous cladding technology is used to perform cladding on both the steel side and the aluminum side at the same time, and the asymmetric thermal stress generated during welding is reduced by balancing the heat input of cladding on both sides.

[0037] Heat input balance and temperature control: During the welding process of the steel side and the aluminum side, the heat input on both sides is balanced by adjusting the current and voltage to avoid a large thermal gradient. This balance can be achieved by monitoring the current, voltage and welding speed. Use a thermocouple to monitor the temperature of the welding area in real time to ensure that the temperature of the steel / aluminum interface is maintained in the range of 200-300°C, promote the moderate diffusion of Fe and Al elements, and avoid the excessive growth of IMC. When the temperature sensor detects a temperature exceeding 300°C, immediately start the CO2 gas-solid mixed welding quenching device to quickly reduce the temperature of the welding area, thereby avoiding the excessive growth of IMC. When the thermocouple detects a temperature below 300°C, stop cooling. When the temperature is further below 200°C, turn on the welding power supply for subsequent deposition.

[0038] Step 3: After the surfacing is completed, turn off all equipment.

[0039] Example 1

[0040] Combined with Figure 1 , the following is a specific implementation method:

[0041] First, the size of the explosive welding joint is determined. When the thickness of the steel side is 6-8 mm and the thickness of the aluminum side is 10-12 mm, the thickness of the aluminum plate is 4 mm higher than that of the steel plate to balance the difference in thermal conductivity between Fe and Al. When performing additive manufacturing operations, the first CO2 welding quenching device 1 is placed in the upper area of ​​the explosive welding joint, and the second CO2 welding quenching device 2 is placed in the lower area of ​​the explosive welding joint.

[0042] Before the start of surfacing welding, the high-strength steel fixing first clamp 5 and the high-strength steel fixing second clamp 6 are used to stabilize the steel-aluminum explosion welding joint to prevent displacement during welding. Subsequently, the first MIG welding gun 15 and the second MIG welding gun 16 of the MIG surfacing equipment are started in sequence, and the steel alloy welding wire 13 is used for surfacing welding on the steel plate 7 side of the explosion welding transition joint, and the aluminum alloy welding wire 14 is used for surfacing welding on the aluminum plate 8 side of the explosion welding transition joint. In order to achieve heat input balance, the current I range of MIG surfacing on the steel side is set to 150-180A, the voltage U is 24-26V, the current I range of the aluminum side is 140-160A, the voltage U is 22-24V, the total power P on both sides is U*I, and the total power on the aluminum side is not less than 80% of the total power on the steel side to balance the heat difference. The welding speed on both sides is the same, both set at 250-350mm / min. The heat input from the arcs on both sides almost cancels each other out, forming a balancing effect, which significantly reduces the temperature difference and thermal stress accumulation at the aluminum / steel interface and reduces welding deformation in the joint area.

[0043] During the welding process, the temperature of the explosive welding head is transmitted back to the first CO2 gas flow regulating device 23 and the second CO2 gas flow regulating device 24 through the first thermocouple 3 and the second thermocouple 4 respectively; when the temperature monitored by the thermocouple temperature sensor exceeds 300°C, the CO2 gas-solid mixed welding rapid cooling device is immediately started, and the first cooling gas 21 and the second cooling gas 22 are sent in to quickly reduce the temperature of the welding area, thereby avoiding the excessive growth of IMC. When the temperature detected by the thermocouple is lower than 300°C, the cooling is stopped, and when the temperature is further lower than 200°C, the welding power supply is turned on for subsequent deposition.

[0044] During the welding process, the first wire feeder 17 and the second wire feeder 18 control the wire feeding speeds of the steel wire 13 and the aluminum wire 14 respectively to ensure uniform formation of the cladding layer. As the cladding layer gradually accumulates, the steel droplets 19 and the aluminum droplets 20 form a stable molten pool on their respective materials, and finally a high-strength aluminum / steel dissimilar metal composite structure is obtained. Figure 2 shown.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 1 is that this comparative example does not use explosive welding to connect the steel plate and the aluminum plate, but directly performs aluminum alloy arc additive manufacturing on the surface of the steel plate. Figure 3As shown, other welding parameter settings are the same as those in Example 1.

[0047] Figure 2 and Figure 3 The additive manufacturing components shown in the figure clearly show that under the same process parameters, the pile without explosive welding transition joint as an intermediate medium cracks within less than 5 cm, while Figure 2 The additively manufactured component showed no signs of cracking.

[0048] The present invention controls the temperature of the steel-aluminum interface through the design of the steel-aluminum explosion welding joint and the cooling device, thereby ensuring the metallurgical quality of the interface and the bonding strength of the cladding layer.

[0049] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for regulating intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing, characterized in that: The following steps are involved: Step 1: pre-treating the surfaces of the areas to be contacted between the steel plate and the aluminum alloy; performing explosion welding on the steel plate and the aluminum alloy to form a welded body, wherein the top and bottom ends of the welded body are fixed by a first clamp (5) and a second clamp (6); a first thermocouple (3) and a first cooling device are installed at the top end of the welded body, and a second thermocouple (4) and a second cooling device are installed at the bottom end; the steel plate is provided with a first MIG welding device (15), and a second MIG welding device (16) is provided on the aluminum alloy side; Step 2: simultaneously start the first MIG welding device (15), the second MIG welding device (16), the first thermocouple (3), and the second thermocouple (4), and weld the steel alloy on the steel plate side and the aluminum alloy on the aluminum alloy side; adjust the welding parameters to ensure the heat input balance on both sides, and adjust the first cooling device and the second cooling device to ensure the temperature of the weld body; Step 3: After the surfacing is completed, the first MIG welding device (15), the second MIG welding device (16), the first thermocouple (3), the second thermocouple (4), the first cooling device, and the second cooling device are turned off.

2. The method for controlling intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing according to claim 1, characterized in that: The top end and the bottom end of the welding body pass through the first clamp (5) and the second clamp (6).

3. The method for controlling intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing according to claim 1, characterized in that: The first thermocouple (3) installed at the top end of the welding body is connected in sequence to the first CO2 gas flow regulating device (23) of the first cooling device, the first cooling gas (21) and the first CO2 welding rapid cooling device (1); the second thermocouple (4) installed at the bottom end of the welding body is connected in sequence to the second CO2 gas flow regulating device (24) of the second cooling device, the second cooling gas (22) and the second CO2 welding rapid cooling device (2).

4. The method for controlling intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing according to claim 3, characterized in that: The first CO2 welding rapid cooling device (1) blows vertically toward the explosion welding joint at the top of the welding body, and the second CO2 welding rapid cooling device (2) blows vertically toward the explosion welding joint at the bottom of the welding body.

5. The method for controlling intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing according to claim 3, characterized in that: When the temperature detected by the first thermocouple (3) and the second thermocouple (4) exceeds 300°C, the first cooling device and the second cooling device are started, and the welding (16) of the first MIG welding device (15) and the second MIG welding device on both sides is stopped; when the temperature detected by the first thermocouple (3) and the second thermocouple (4) is lower than 300°C, the first cooling device and the second cooling device are stopped; when the temperature detected by the first thermocouple (3) and the second thermocouple (4) is lower than 200°C, the first MIG welding device (15) and the second MIG welding device on both sides are started for welding (16).

6. The method for controlling intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing according to claim 1, characterized in that: The thickness of the aluminum alloy is 4 mm thicker than that of the steel plate; the thickness of the steel plate is 6 to 8 mm, and the thickness of the aluminum alloy is 10 to 12 mm.

7. The method of the device for controlling intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing according to claim 1, characterized in that: The welding speed on the steel plate side is 250-350 mm / min, and the surfacing current I 铝 150~180A, voltage U 铝 It is 24~26V.

8. The method for controlling intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing according to claim 1, characterized in that: The welding speed of the aluminum alloy side is 250-350 mm / min, and the surfacing current I 钢 140~160A, voltage U 钢 It is 22~24V.

9. The method of the device for controlling intermetallic compounds at the interface of steel-aluminum dissimilar metal double-sided arc additive manufacturing according to claim 1, characterized in that: The total power P of the aluminum alloy side 铝 =U 铝 I 铝 Not less than the total power P on the steel side 钢 =U 钢 I 钢 80% of.

Images