A method for repairing cracks in copper and copper alloys based on friction stir repair

Abstract

The application discloses a copper and copper alloy crack repairing method based on friction stir repair, and relates to the technical field of defect repairing, and comprises the following steps: step S1, pretreating copper material, and machining irregular cracks into regular grooves; step S2, selecting welding wire, feeding the welding wire into the groove, and pre-connecting the welding wire and the groove by arc preheating; step S3, performing friction stir processing on the pre-connected part of the welding wire, and repairing the groove by the thermal-mechanical coupling effect; and step S4, repeatedly performing steps S2 and S3 according to the groove depth and width to realize single-layer or multi-layer repairing of the welding wire in the groove until the groove is completely repaired. The application realizes the friction stir repairing process of large-size cracks and irregular cracks by combining cutting processing, arc preheating processing and friction stir repair, has low heat input, high repairing quality and a wider application range.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material repair, in particular to a copper and copper alloy crack repair method based on friction stir repair. BACKGROUND

[0002] Copper and copper alloy are widely used in electrical, light industry, machinery manufacturing, construction industry, defense industry, shipbuilding and aerospace fields due to their excellent electrical conductivity, thermal conductivity, wear resistance, strong plasticity matching and corrosion resistance. In the industrial application of copper, it is often used as an engineering structural part, including relays, transformers, electrical vacuum devices, and various containers, pipeline systems that contact corrosive media, etc.

[0003] However, the reliability and service life of mechanical products have become a problem to be solved in China's equipment manufacturing industry. Common engineering structural parts will produce a large number of defects on the surface during service due to external force impact, environmental corrosion, wear and other factors. The most common and most serious of which is crack. Taking the crystallizer, the heart of the continuous casting machine, as an example, the copper plate of the crystallizer is subjected to long-term impact and corrosion of molten steel, combined with friction with the steel billet, which easily leads to erosion and local micro-cracks, and under the action of continuous load, the cracks gradually expand and break, eventually leading to structural failure. The traditional repair process of the crystallizer is to machine the copper plate substrate offline to remove 1.5mm-2.5mm of surface defects. This method can only repair about seven times per copper plate of the crystallizer, consuming a large amount of copper resources and increasing the cost of continuous casting. Therefore, it is of great economic benefit and resource utilization value to realize the repair of copper and copper alloy structural parts with crack defects.

[0004] The commonly used crack repair methods currently include traditional fusion welding, electric spark alloying, and laser multi-layer cladding technologies. However, due to the melting-solidification process, secondary defects such as pores and cracks will inevitably occur during the repair process. In addition, excessive local heat input can easily cause the grains in the repair area to become coarse, and the large residual stress can affect the mechanical properties of the repair area. At the same time, for irregularly shaped cracks and large-sized cracks on copper and copper alloy structural parts, there are problems of difficulty in repair and unstable performance in the existing technology. SUMMARY

[0005] The problem solved by the present application is how to improve the difficulty in repairing large-sized irregularly shaped cracks in copper and copper alloy.

[0006] To solve the above problems, the present application provides a copper and copper alloy crack repair method based on friction stir repair, comprising the following steps:

[0007] Step S1: pretreating the copper material, and machining the irregular cracks into regular grooves;

[0008] Step S2: selecting a welding wire, preheating the welding wire by arc to melt it and pre-connect it with the groove while feeding the welding wire into the groove;

[0009] Step S3: friction stir processing the pre-connected part of the welding wire to repair the groove by thermal-mechanical coupling;

[0010] Step S4: repeating steps S2 and S3 to realize single-pass multi-layer or multi-pass multi-layer repair of the welding wire in the groove according to the depth and width of the groove until the groove is completely repaired.

[0011] Further, in step S1, the cutting process is semi-finishing or roughing.

[0012] Further, in step S2, before feeding, the groove is also cleaned with alcohol to remove surface impurities.

[0013] Further, in step S2, selecting the welding wire includes selecting a welding wire of the same material as the copper material to be repaired or a welding wire of enhanced material.

[0014] Further, in step S2, the number of welding wires includes one or more.

[0015] Further, in step S2, the temperature of the arc preheating is 150-300℃, the current of the arc is 50-150A, the AC parameter is 180Hz, and the duty cycle is 80%.

[0016] Further, in step S2, the arc preheating is preheated by TIG arc, and during preheating, a lanthanum-tungsten needle with a diameter of 2.4mm is used, the angle between the lanthanum-tungsten needle and the bottom of the groove is 60°, the distance between the lanthanum-tungsten needle and the shaped substrate is 2mm, the angle between the wire feeding direction and the shaped substrate is 30°, the wire material extends out of the wire feeding nozzle by 10mm, and the protective gas flow is 15-16L / min.

[0017] Further, in step S3, the stir pin is provided on the stir head used in the friction stir processing, the number of stir pins is 1-7, and the material of the stir pin is H2-R42 high-speed steel.

[0018] Further, in step S3, the rotation speed of the stir head during the friction stir processing includes 600-2000rpm, the travel speed includes 50-300mm / min, the pressing amount is 0.1-1mm, and the inclination angle is 0-2.5°.

[0019] Further, in step S3, the travel direction of the stir head during the friction stir processing is matched with the structure of the groove.

[0020] The copper and copper alloy crack repairing method based on the friction stir repair has the beneficial effects that:

[0021] The application can overcome the defects of the traditional melting repair, avoid the secondary defects such as pores and cracks generated in the melting and solidification process, obtain fine equiaxed crystal structure under the thermal-mechanical coupling effect with low heat input, and has good mechanical properties in the repairing area; the application can also overcome the limitations of the traditional friction stir repair technology, realize the friction stir repair process of large-size cracks and irregular cracks through the cutting processing and arc preheating process of irregular cracks; meanwhile, the method can avoid the weld thinning problem in the traditional friction stir additive process, can fully repair the cracks, and is more suitable for repairing large-size cracks; the method can realize the continuous wire feeding, arc preheating and friction stir repair integrated repair process, has higher efficiency, wider application range, is simple and feasible, and is easy to operate. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a schematic diagram of the copper and copper alloy crack repairing process based on the friction stir repair in the embodiment of the application;

[0023] Figure 2 is a schematic diagram of the crack on the original substrate in the embodiment of the application;

[0024] Figure 3 is a schematic diagram of the regular groove after the cutting processing of the irregular crack in the embodiment of the application;

[0025] Figure 4 is a schematic diagram of the structure of the stirring head in the embodiment of the application;

[0026] Figure 5 is a schematic diagram of the structure of the arc heating welding wire in the embodiment of the application;

[0027] Figure 6 is a partial cross-sectional view of the crack repairing process by the stirring pin friction stir in the embodiment of the application;

[0028] Figure 7 is a schematic diagram of the copper and copper alloy crack repairing process based on the friction stir repair in the embodiment 2 of the application.

[0029] BRIEF DESCRIPTION OF DRAWINGS

[0030] 1-original substrate; 101-original crack; 2-shaped substrate; 201-groove; 3-stirring head; 4-arc heating nozzle; 5-welding wire. DETAILED DESCRIPTION

[0031] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings. The present application will be further described in detail below: the embodiments are implemented on the premise of the technical solutions of the present application, and detailed implementation modes are given, but the protection scope of the present application is not limited to the following embodiments.

[0032] Specifically, the embodiment of the present application provides a copper and copper alloy crack repair method based on friction stir repair, comprising the following steps:

[0033] Step S1: pretreating the copper material, cutting the irregular cracks into regular grooves;

[0034] Step S2: selecting a welding wire 5, feeding the welding wire 5 to the groove while preheating the welding wire 5 by an electric arc to melt the welding wire 5 and realize pre-connection with the groove;

[0035] Step S3: friction stir processing the pre-connection part of the welding wire 5 to realize repair of the groove through thermal-mechanical coupling effect;

[0036] Step S4: according to the groove depth and width, repeating steps S2 and S3 to realize single-layer or multi-layer repair of the welding wire 5 in the groove until the groove is completely repaired.

[0037] The embodiment of the present application can overcome the drawbacks of traditional melting repair, avoid secondary defects such as pores and cracks generated in the melting and solidification process, and obtain fine equiaxed crystal structure under the action of thermal-mechanical coupling with low heat input, so that the repair area has good mechanical properties; the embodiment of the present application can also overcome the limitations of traditional friction stir repair technology, and realize friction stir repair of large-size cracks and irregular cracks through the processes of cutting irregular cracks and electric arc preheating; at the same time, the method can avoid the problem of weld thinning in the traditional friction stir additive process, can fully repair cracks, and is more suitable for the repair of large-size cracks; the embodiment method of the present application can realize continuous wire feeding and integrated repair process of electric arc preheating and friction stir repair, has higher efficiency, wider application range, is simple, feasible and easy to operate.

[0038] Specifically, as Figure 2 and Figure 3As shown, the copper material in step S1 generally refers to metal copper or copper alloy, and for large-size irregular cracks, that is, the crack depth and width change with the path, the traditional friction stir repair method cannot be directly used for repair or will cause serious weld thinning problem, so that the repaired copper material cannot meet the use requirements. Therefore, in order to reduce the repair difficulty, the irregular crack is processed into a regular groove suitable for repair by cutting processing, and the repair path is adapted, thereby providing favorable conditions for the next step of repair. For example, the irregular crack can be processed into a square groove.

[0039] Specifically, in step S2, as shown in Figure 5 The welding wire 5 with the same material as the material to be repaired can be selected, and the welding wire 5 is melted and pre-connected with the groove by arc preheating while the welding wire 5 is fed. In this process, the temperature of the arc preheating is lower than that of other traditional repair methods, so as to avoid secondary defects such as pores and cracks generated in the traditional melting and solidification process. The heat input of the arc preheating process is low, and under the action of thermal-mechanical coupling, fine equiaxed crystal structure can be obtained, so that the repaired area has good mechanical properties.

[0040] Step S3 is repaired by friction stir processing in cooperation with the arc preheating in step S2, that is, the repair of the groove is realized by thermal-mechanical coupling. The heat input is low, the defects are few, and the repair effect is better.

[0041] In step S4, for large-size grooves, single-layer or multi-layer repair can be used by laying the welding wire 5 and combining friction stir processing with arc preheating, so as to improve the repair precision and ensure the mechanical properties and flatness of the material.

[0042] In some embodiments, in step S1, the cutting processing is semi-finishing or rough machining. Thus, the connection effect of the pre-connection is improved, and stress concentration at the connection is prevented.

[0043] In some embodiments, in step S2, before the wire feeding, the groove is cleaned by alcohol to remove surface impurities. Thus, the influence of impurities is reduced, and the repair quality is improved.

[0044] In some embodiments, in step S2, the selection of the welding wire 5 includes: selecting a welding wire 5 with the same material as the copper material to be repaired or a welding wire 5 with enhanced material. Specifically, the repair process needs additive repair, and the same material welding wire 5 can be selected for repair to ensure the consistency of the material and reduce the influence of uneven material on crack quality. Other welding wire 5 materials with enhanced performance can also be selected to strengthen the weld metal by using Orowan strengthening mechanism, load transfer mechanism, dislocation strengthening mechanism and other mechanisms, thereby improving the performance of the material.

[0045] In some embodiments, in step S2, the number of wire feeding includes one or more. Thus, the wire feeding is flexible, adjusted according to the actual width and depth of the groove, simple operation, and high efficiency.

[0046] In some embodiments, in step S2, the temperature of the arc preheating is 150-300℃, the arc current is 50-150A, the AC parameter is 180Hz, and the duty cycle is 80%. Thus, the temperature of the arc preheating is relatively low, which can reduce the generation of secondary defects, and the parameters are easy to control, reducing the operation difficulty.

[0047] In some embodiments, as shown in Figure 6 In step S2, the arc preheating is preheated by TIG arc, and during the preheating, a lanthanum tungsten needle with a diameter of 2.4mm is used, the angle between the lanthanum tungsten needle and the bottom of the groove is 60°, the distance between the lanthanum tungsten needle and the shaped substrate is 2mm, the angle between the wire feeding direction and the shaped substrate is 30°, the wire feeding distance from the wire feeding nozzle is 10mm, and the protective gas flow is 15-16L / min. Thus, the repair quality is higher and the performance is more excellent.

[0048] In some embodiments, in step S3, the stir pin is provided on the stir head 3 used in the friction stir processing, the number of stir pins is 1-7, and the material of the stir pin is H2-R42 high-speed steel. Thus, the effect of the friction stir processing is more conducive to the balance of mechanical properties, improving the repair quality.

[0049] In some embodiments, in step S3, the rotation speed of the stir head 3 during the friction stir processing includes 600-2000rpm, the travel speed includes 50-300mm / min, the pressing amount is 0.1-1mm, and the inclination angle is 0-2.5°. Thus, it is suitable for copper materials, improving the repair quality.

[0050] In some embodiments, as shown in Figure 1 and Figure 7 In step S3, the travel direction of the stir head 3 during the friction stir processing is matched with the groove structure. Thus, the path is planned in advance according to the groove structure, the repair is completed efficiently and quickly, saving time and effort.

[0051] Embodiment 1

[0052] The embodiment is a copper and copper alloy crack repair method based on friction stir repair, which includes the following steps:

[0053] Step S1: as shown in Figure 2 , 3The material to be repaired is a chromium zirconium copper plate as the original substrate 1. According to the morphology of the original crack 101, it is cut and processed to form a regular square groove, resulting in a shaped substrate 2. After processing, it is ultrasonically cleaned for 15 minutes and then dried. The groove 201 is cleaned with alcohol to ensure that the surface of the groove is clean and free of impurities.

[0054] Step S2: As Figure 5 As shown, two welding wires 5 of the same material as the material to be repaired are selected. The welding wire 5 is C18150 welding wire. It is laid flat at the bottom of the groove and preheated with TIG arc. The arc heating nozzle 4 is a lanthanum tungsten needle with a diameter of 2.4mm. The angle between the lanthanum tungsten needle and the bottom of the groove is 60°. The distance between the lanthanum tungsten needle and the shaped substrate 2 is 2mm. The angle between the wire feeding direction and the shaped substrate 2 is 30°. The shielding gas flow rate is 15-16L / min. The preheating temperature is 150-300℃. The arc current is 50-150A. The welding wire 5 is partially melted and pre-connected to the groove opening.

[0055] Step S3: As Figure 4 , 6 As shown, the stirring head 3 is a needle-type stirring head 3, with three stirring needles. The stirring needle material is high-speed steel (H2-R42), and its shoulder diameter is larger than the groove width. The rotation speed of the stirring head 3 and the stirring needles is 600-2000 rpm, the travel speed is 50-300 mm / min, and the downward pressure is 0.1-0.5 mm. The downward pressure is based on the upper surface of the shaped substrate 2, and the tilt angle is 0-2.5°. Under the intense stirring friction brought by the stirring head 3, the material undergoes sufficient plasticization and uniform flow, forming an effective connection between the welding wire 5 and the shaped substrate 2, forming... Figure 6 .

[0056] Step S4: Repeat steps S2 and S3. On the basis of repairing one layer, continue to lay the welding wire 5 flat and repeat the steps of arc preheating and friction stir repair. The arc preheating height gradually increases as the bottom of the groove rises, while the height of the stirring head 3 remains unchanged in the subsequent process to ensure sufficient heat input, and finally realize the single-pass multi-layer repair process.

[0057] Example 2

[0058] This embodiment is a method for repairing cracks in copper and copper alloys based on friction stir repair, which includes the following steps:

[0059] Step S1: The material to be repaired is a chromium zirconium copper plate as the original substrate 1. According to the morphology of the original crack 101, it is cut and processed to form a regular square groove, resulting in a shaped substrate 2. After processing, it is ultrasonically cleaned for 15 minutes and then dried. The groove 201 is cleaned with alcohol to ensure that the surface of the groove is clean and free of impurities.

[0060] Step S2: As Figure 5 As shown, two welding wires 5 of the same material as the material to be repaired are selected. The welding wires 5 are C18150 welding wires, which are laid flat at the bottom of the groove. TIG arc preheating is used. The arc heating nozzle 4 is a lanthanum tungsten needle with a diameter of 2.4 mm. The angle between the lanthanum tungsten needle and the bottom of the groove is 60°. The distance between the lanthanum tungsten needle and the shaped substrate 2 is 2 mm. The angle between the wire feeding direction and the shaped substrate 2 is 30°. The shielding gas flow rate is 15-16 L / min. The preheating temperature is 150-300℃. The arc current is 50-150 A, so that the welding wire 5 is partially melted and pre-connected to the groove opening.

[0061] Step S3: As Figure 7 As shown, the stirring head 3 is a needle-type stirring head with three stirring needles made of high-speed steel (H2-R42). The groove width is relatively large, while the shoulder size is smaller than the groove width. The stirring head 3 rotates at 600-2000 rpm, travels at 50-300 mm / min, and applies a downward pressure of 0.1-0.5 mm, with the pressure referenced to the bottom of the groove and an inclination angle of 0-2.5°. The intense stirring friction from the stirring head 3 causes the material to undergo sufficient plasticization and uniform flow, resulting in an effective connection between the welding wire 5 and the shaped substrate 2.

[0062] Step S4: Since the bottom of the groove is large, move the repair device along the width of the groove and repeat steps S2 and S3. After multiple single layers are completed, change the height of the stirring head 3 and the arc nozzle, and repeat the above steps again to finally achieve multi-layer repair.

[0063] The difference between Example 2 and Example 1 is that the crack size in Example 2 is larger, and the method can achieve a multi-stage repair process.

[0064] Therefore, the embodiments of the present invention can overcome the drawbacks of traditional melting repair, avoid secondary defects such as pores and cracks generated during the melting and solidification process, have low heat input, and can obtain fine equiaxed grain structure under thermo-mechanical coupling, resulting in good mechanical properties in the repaired area. Furthermore, it overcomes the limitations of traditional friction stir repair technology, enabling the friction stir repair of large-size and irregular cracks through the cutting and preheating process of irregular cracks. Simultaneously, this method avoids the weld thinning problem in traditional friction stir additive manufacturing, fully repairs cracks, is more suitable for repairing large-size cracks, is highly efficient, has a wide range of applications, is simple and feasible, and is easy to operate.

[0065] The above merely describes preferred specific embodiments of the present application, which are all different implementations based on the overall concept of the present application, and the protection scope of the present application is not limited thereto, any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application shall be encompassed within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method for repairing cracks in copper and copper alloys based on friction stir repair, characterized in that, Includes the following steps: Step S1: Use copper material as the original substrate (1) and pre-treat it. Cut irregular cracks into regular grooves. To improve the connection effect of pre-connection, the cutting process is semi-finishing or roughing, and then the shaped substrate (2) is obtained. Step S2: Select a welding wire of the same material as the copper material to be repaired or a welding wire of a reinforcing material. While continuously feeding the wire into the groove, set the arc preheating temperature to 150-300℃, the arc current to 50-150A, the AC parameters to 180Hz, and the duty cycle to 80%. The arc preheating is performed using a TIG arc to partially melt the welding wire and pre-connect it to the groove. During preheating, a lanthanum tungsten needle with a diameter of 2.4mm is used. The angle between the lanthanum tungsten needle and the bottom of the groove is 60°. The distance between the lanthanum tungsten needle and the shaped substrate (2) is 2mm. The angle between the wire feeding direction and the shaped substrate (2) is 30°. The distance of the wire extending from the wire feeding nozzle is 10mm. The protective gas flow rate is 15-16L / min. Step S3: The pre-connected portion of the welding wire is subjected to friction stirring treatment to obtain a fine equiaxed crystal structure through thermo-mechanical coupling, thereby achieving the repair of the groove; Step S4: Based on the depth and width of the groove, repeat steps S2 and S3 to perform single-pass multi-layer or multi-pass multi-layer repair of the welding wire in the groove until the groove is completely repaired.

2. The method for repairing copper and copper alloy cracks based on friction stir repair according to claim 1, characterized in that, In step S2, before wire feeding, the groove is cleaned with alcohol to remove surface impurities.

3. The method for repairing copper and copper alloy cracks based on friction stir repair according to claim 1, characterized in that, In step S2, the number of wires fed includes one or more.

4. The method for repairing copper and copper alloy cracks based on friction stir repair according to claim 1, characterized in that, In step S3, the stirring head used in the friction stirring treatment is equipped with stirring pins, the number of stirring pins is 1-7, and the stirring pins are made of H2-R42 high-speed steel.

5. The method for repairing copper and copper alloy cracks based on friction stir repair according to claim 4, characterized in that, In step S3, the stirring head rotation speed during the stirring friction treatment includes 600-2000 rpm, the travel speed includes 50-300 mm / min, the downward pressure is 0.1-1 mm, and the tilt angle is 0-2.5°.

6. The method for repairing copper and copper alloy cracks based on friction stir repair according to claim 5, characterized in that, In step S3, the direction of travel of the stirring head during the stirring friction treatment is matched with the structure of the groove.

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