Composite board welding method

Abstract

The invention discloses a composite board welding method, which adopts a specific chromium-nickel welding wire containing a molybdenum element, uses laser arc hybrid welding equipment for welding, and comprises the following steps: S1, pretreating a welding joint of a to-be-welded composite board; s2, the to-be-welded composite board is preheated; s3, the to-be-welded composite board is fixed, and a welding seam gap of 1-10 mm is reserved at a welding joint; and S4, the laser-arc hybrid welding equipment is started to weld the composite plate to be welded, and the welding parameters are as follows: the laser power is 3.6-4.4 KW, the wire feeding speed is 3.8-4.6 m / min, and the welding speed is 1.90-2.40 m / min. According to the method, the DH36 + S31254 composite plate can be stably and efficiently welded, operation is easy, the welding quality is stable, and the welding seam performance is excellent.

Description

Technical Field

[0001] This application relates to the field of welding technology, and in particular, to a welding method for composite plates. Background Art

[0002] Ship welding technology is one of the key technologies in the modern shipbuilding field, directly affecting the efficiency and quality of shipbuilding. In recent years, the rapidly developing laser-arc hybrid welding technology has gradually replaced the traditional arc welding technology and has been increasingly applied in the shipbuilding field. The laser-arc hybrid welding technology combines laser and arc, utilizes the deep penetration ability of the laser and the bridging ability of the arc, can truly achieve single-sided welding with double-sided forming, reduces the welding of plate turning and lifting lugs, gives full play to the advantages of laser welding and arc welding, and makes up for their respective deficiencies, thereby effectively improving the welding quality and welding efficiency.

[0003] In recent years, with the continuous development of the shipbuilding industry, ship plates have gradually developed from single materials to composite materials. Traditional single-material plates, such as DH36 high-strength ship plates, although having high strength and toughness, have relatively low corrosion resistance. And plates with excellent corrosion resistance, such as S31254 super austenitic stainless steel plates, have extremely excellent seawater corrosion resistance, but there is an obvious gap in strength and toughness compared with DH36 high-strength ship plates. Composite plates with DH36 as the cladding layer and S31254 as the base layer are very excellent in terms of strength, toughness, and seawater corrosion resistance, and are currently relatively high-end ship composite plates.

[0004] For the welding of the above composite plates, it is a major problem in the current field. Due to the differences in thermophysical properties and chemical compositions between the base layer and the cladding layer of the above composite plates, there are many problems in using laser-arc hybrid welding. First, during the welding process, it is very easy to melt the cladding layer when welding the base layer, which will lead to hardening and embrittlement of the weld metal and generate welding cracks. Second, the dilution effect of the base layer weld on the cladding layer weld will reduce the chromium and nickel content in the cladding layer weld and increase the carbon content, thereby reducing the plasticity and corrosion resistance of the welded joint. In addition, due to the low thermal conductivity and large thermal expansion coefficient of the above composite plates, large welding deformation and stress are easily generated during the welding process. Based on the above problems, it is difficult to operate and ensure the welding quality when using laser-arc hybrid welding technology to weld DH36+S31254 composite plates, and it is difficult to meet the requirements of ship welding. Summary of the Invention

[0005] In order to solve at least one of the above technical problems and develop a laser-arc hybrid welding method that can stably and efficiently weld DH36+S31254 composite plates, is easy to operate, has stable welding quality and excellent weld properties, this application provides a welding method for composite plates.

[0006] The present application provides a composite plate welding method, which uses a laser-arc hybrid welding device for welding, and includes the following steps:

[0007] S1. Pretreat the welding joint of the composite plate to be welded to ensure the joint is clean;

[0008] S2. Preheat the composite plate to be welded pretreated in step S1;

[0009] S3. Fix the composite plate to be welded preheated in step S2, and leave a weld gap of 1-10 mm wide at the welding joint;

[0010] S4. Start the laser-arc hybrid welding device to weld the composite plate to be welded fixed in step S3, and the welding parameters are: laser power 3.6-4.4 KW, wire feeding speed 3.8-4.6 m / min, welding speed 1.90-2.40 m / min;

[0011] The mass ratio of each chemical component of the welding wire is: carbon 0.020-0.024%, manganese 0.14-0.18%, silicon 0.38-0.52%, chromium 20.45-21.35%, nickel 9.6-10.0%, molybdenum 0.42-0.48%, copper 0.12-0.18%, cobalt 0.1-0.5%, nitrogen 0.04-0.06%, and the balance is iron and unavoidable impurities.

[0012] Optionally, in step S1, the pretreatment includes grinding the burrs at the welding joint and cleaning the welding joint.

[0013] Optionally, in step S2, the preheating temperature is 120-150 °C.

[0014] Further optionally, in step S2, the preheating time is 30-45 min.

[0015] Optionally, in step S4, the welding parameters are: laser power 4.0-4.2 KW, wire feeding speed 4.0-4.2 m / min, welding speed 2.00-2.10 m / min.

[0016] Optionally, in step S4, the welding current is 120 A and the welding voltage is 12 V.

[0017] Optionally, in step S4, the interlayer temperature is controlled at 130-150 °C.

[0018] Optionally, after step S4, there is also a treatment step of grinding and heat treating the weld.

[0019] Further optionally, the heat treatment includes the following steps: First, the welded composite plate is vacuum heated to 480 - 540 °C and held for 10 - 30 min; then, it is cooled to room temperature in the furnace.

[0020] Even further optionally, the heating rate is controlled at 8 - 12 °C / min.

[0021] In summary, the present invention includes at least one of the following beneficial technical effects:

[0022] 1. This application designs a laser - arc hybrid welding method for ship - used DH36 + S31254 composite plates. By using specific welding wires and welding parameters, it can achieve stable welding of the above - mentioned specific composite plates, and the welded welds have excellent mechanical properties and corrosion resistance, effectively avoiding the generation of welding cracks and the occurrence of welding deformation.

[0023] 2. This application can achieve stable and high - quality welding of ship - used DH36 + S31254 composite plates, is very suitable for existing automated laser - arc hybrid welding equipment, has a relatively fast welding speed, and can effectively improve the welding efficiency.

[0024] 3. This application can be applied to the welding of ship - used DH36 + S31254 composite plates of various models and sizes, has extremely high welding precision, and the operation difficulty is relatively low. Description of the Drawings

[0025] Figure 1 is a cross - section photo of the weld in Example 1 of this application;

[0026] Figure 2 is a photo of the cross - section morphology of the weld in Example 10 of this application;

[0027] Figure 3 is an electron microscope image of the base - layer weld in Example 1 of this application;

[0028] Figure 4 is a photo of the weld in Examples 3 - 8 of this application;

[0029] Figure 5 is a treatment photo of the salt - spray corrosion resistance test of this application. Detailed Description of the Embodiments

[0030] The following further elaborates on this application in conjunction with the drawings and embodiments.

[0031] Unless otherwise specified, the raw materials used in this application are conventional raw materials in the technical field and can all be obtained on the market. In the test methods and detection methods of the following embodiments, unless otherwise specified, they are all conventional methods, and the instruments and apparatuses used in the tests can all be obtained through commercial channels. The parts not elaborated in detail in this specification all belong to the prior art.

[0032] This application designs a composite plate welding method, which uses a laser-arc hybrid welding device for welding, including the following steps:

[0033] S1. Pretreat the welding joint of the composite plate to be welded to ensure that the joint is clean;

[0034] S2. Preheat the composite plate to be welded after being pretreated in step S1;

[0035] S3. Fix the composite plate to be welded after being preheated in step S2, leaving a weld gap of 1-10 mm wide at the welding joint;

[0036] S4. Start the laser-arc hybrid welding device to weld the composite plate to be welded fixed in step S3. The welding parameters are: laser power 3.6-4.4 KW, wire feeding speed 3.8-4.6 m / min, welding speed 1.90-2.40 m / min;

[0037] The mass ratio of each chemical component of the welding wire is: carbon 0.020-0.024%, manganese 0.14-0.18%, silicon 0.38-0.52%, chromium 20.45-21.35%, nickel 9.6-10.0%, molybdenum 0.42-0.48%, copper 0.12-0.18%, cobalt 0.1-0.5%, nitrogen 0.04-0.06%, and the balance is iron and unavoidable impurities.

[0038] Currently, for the welding of DH36+S31254 composite plates in the prior art, arc welding is generally used. There are many problems when using laser-arc hybrid welding. The core is that there are differences in the thermophysical properties and chemical compositions between DH36 steel and S31254 steel.

[0039] To solve the problems existing in the prior art, this application first designs a special welding wire with relatively high chromium and nickel contents and also contains a small amount of molybdenum and other elements. In addition, a welding process is designed specifically and the process parameters are further optimized. In the above design, the welding wire of a specific material can ensure that the material of the welding wire can match both DH36 steel and S31254 steel at the same time. The specially designed welding process uses narrow-gap welding, which can reduce the heat-affected zone of the welding joint. At the same time, by using a small current, a specific laser power, and a relatively fast welding speed, the welding quality can be precisely controlled, and the hardening and embrittlement of the weld metal can be reduced.

[0040] The following are the preparation examples and implementation examples of this application.

[0041] Preparation Example 1

[0042] The element ratio of the welding wire in this preparation example is as follows: carbon 0.020%, manganese 0.14%, silicon 0.38%, chromium 20.45%, nickel 9.6%, molybdenum 0.42%, copper 0.12%, cobalt 0.1%, nitrogen 0.04%, and the balance is iron.

[0043] The preparation of the welding wire in this preparation example adopts the following steps:

[0044] Sa. Weigh the raw materials accurately according to the ratio, and all raw materials are pure element raw materials;

[0045] Sb. Put the raw materials of pure iron, pure chromium, pure nickel and pure molybdenum into a vacuum induction furnace, heat to 1650 - 1660 °C, and melt the alloy liquid;

[0046] Sc. Add the raw materials of other elements except carbon element to the alloy liquid, cool down to 1550 - 1560 °C, and melt the alloy liquid;

[0047] Sd. Add carbon element to the alloy liquid, heat up to 1590 - 1600 °C for refining, and then pour it into a steel alloy billet;

[0048] Se. After heat - treating the steel alloy billet, hot - roll it into a steel alloy bar, and then conduct cold drawing treatment to obtain the welding wire.

[0049] Preparation Example 2

[0050] The difference between this preparation example and Preparation Example 1 lies in the element ratio of the welding wire.

[0051] The element ratio of the welding wire in this preparation example is as follows: carbon 0.024%, manganese 0.18%, silicon 0.52%, chromium 21.35%, nickel 10.0%, molybdenum 0.48%, copper 0.18%, cobalt 0.5%, nitrogen 0.06%, and the balance is iron.

[0052] Preparation Example 3

[0053] The difference between this preparation example and Preparation Example 1 lies in the element ratio of the welding wire.

[0054] The element ratio of the welding wire in this preparation example is as follows: carbon 0.022%, manganese 0.15%, silicon 0.45%, chromium 20.95%, nickel 9.8%, molybdenum 0.45%, copper 0.15%, cobalt 0.2%, nitrogen 0.05%, and the balance is iron.

[0055] The following are the examples of the present application. The methods in the examples of the present application are all for the ship - used DH36 + S31254 composite plate with a thickness of 15 mm; among them, the thickness of the base layer DH36 is 12 mm, and the surface cladding layer is the S31254 layer with a thickness of 3 mm.

[0056] Example 1

[0057] In this embodiment, the welding wire prepared in Preparation Example 1 is selected, and the diameter of the welding wire is 2.5 mm.

[0058] For the composite plate welding method of this embodiment, a laser-arc hybrid welding device is used for welding, which includes the following steps:

[0059] S1. The welding joint of the composite plate to be welded is subjected to alcohol washing and water washing, and then dried to ensure the cleanliness of the joint;

[0060] S2. The composite plate to be welded pretreated in step S1 is preheated, with a preheating temperature of 105 °C and a preheating time of 35 min;

[0061] S3. The composite plate to be welded preheated in step S2 is fixed, leaving a weld gap of 6 mm wide at the welding joint;

[0062] S4. Start the laser-arc hybrid welding device to weld the composite plate to be welded fixed in step S3. The welding parameters are: laser power 3.6 KW, wire feeding speed 3.8 m / min, welding speed 1.90 m / min, welding current 150 A, and welding voltage 12 V;

[0063] S5. The weld of the welded composite plate is polished to polish the piled-up protrusions formed by welding.

[0064] Example 2

[0065] The difference between this embodiment and Example 1 is that in step S4, the welding parameters are: laser power 4.4 KW, wire feeding speed 4.6 m / min, and welding speed 2.40 m / min.

[0066] Example 3

[0067] The difference between this embodiment and Example 1 is that in step S4, the welding parameters are: laser power 4.0 KW, wire feeding speed 4.0 m / min, and welding speed 2.00 m / min.

[0068] Example 4

[0069] The difference between this embodiment and Example 1 is that in step S4, the welding parameters are: laser power 4.2 KW, wire feeding speed 4.2 m / min, and welding speed 2.10 m / min.

[0070] Example 5

[0071] The difference between this embodiment and Example 1 is that in step S4, the welding parameters are: laser power 4.0 KW, wire feeding speed 4.15 m / min, and welding speed 2.04 m / min.

[0072] Example 6

[0073] The difference between this embodiment and Embodiment 5 is that in step S4, the welding current is 120 A and the welding voltage is 12 V.

[0074] Embodiment 7

[0075] The difference between this embodiment and Embodiment 6 is that in step S2, the preheating temperature is 150 °C and the preheating time is 30 min.

[0076] Embodiment 8

[0077] The difference between this embodiment and Embodiment 6 is that in step S2, the preheating temperature is 120 °C and the preheating time is 45 min.

[0078] Embodiment 9

[0079] The difference between this embodiment and Embodiment 6 is that in step S2, the preheating temperature is 135 °C and the preheating time is 40 min.

[0080] Embodiment 10

[0081] The difference between this embodiment and Embodiment 9 is that in step S4, the interlayer temperature needs to be controlled at 130 - 150 °C during welding.

[0082] Embodiment 11

[0083] The difference between this embodiment and Embodiment 10 is that the welding wire prepared in Preparation Example 2 is selected, and the wire diameter is 2.5 mm.

[0084] Embodiment 12

[0085] The difference between this embodiment and Embodiment 10 is that the welding wire prepared in Preparation Example 3 is selected, and the wire diameter is 2.5 mm.

[0086] Comparative Example 1

[0087] In this comparative example, the composite plate is welded by an arc welding process. The DWA-55LSR flux-cored wire is selected and protected by carbon dioxide.

[0088] Welding parameters: voltage 25 V, current 180 A, wire feeding speed 7.5 m / min, welding speed 280 mm / min.

[0089] Comparative Example 2

[0090] The difference between this comparative example and Comparative Example 1 is that the welding wire prepared in Preparation Example 1 of this application is used.

[0091] Comparative Example 3

[0092] The difference between this comparative example and Embodiment 10 is that the preheating step in step S2 is not adopted.

[0093] Comparative Example 4

[0094] The difference between this comparative example and Example 10 is that in step S4, the welding parameters are: laser power 4.6 KW, wire feeding speed 4.15 m / min, and welding speed 2.04 m / min.

[0095] Comparative Example 5

[0096] The difference between this comparative example and Example 10 is that in step S4, the welding parameters are: laser power 4.0 KW, wire feeding speed 4.7 m / min, and welding speed 2.04 m / min.

[0097] Comparative Example 6

[0098] The difference between this comparative example and Example 10 is that in step S4, the welding parameters are: laser power 4.0 KW, wire feeding speed 4.15 m / min, and welding speed 2.50 m / min.

[0099] Comparative Example 7

[0100] The difference between this comparative example and Example 10 is that DWA-55LSR flux-cored wire is selected.

[0101] Weld performance detection:

[0102] The DH36+S31254 composite plate for ships used in the examples and comparative examples of this application is purchased from the market. After testing, the mechanical properties of this composite plate are: tensile strength 562 MPa, yield strength 408 MPa, elongation 26.2%; the corrosion resistance of this composite plate is: no corrosion on the surface after 120 hours of salt spray treatment.

[0103] The welded composite plates of Examples 1 to 12 and Comparative Examples 1 to 7 of this application are all stress-relieved before testing. The specific treatment steps are as follows:

[0104] First, the welded composite plate is processed at a temperature of 85 °C in a vibration aging treatment device at a vibration frequency of 100 Hz and a vibration power of 1 kW for 30 min;

[0105] Then, the welded composite plate is processed at a temperature of 150 °C in a vibration aging treatment device at a vibration frequency of 100 Hz and a vibration power of 2 kW for 45 min, and then naturally cooled to room temperature.

[0106] Using a universal testing machine, according to the method described in ASTM:E8 / E8M-11, the tensile strength, yield strength, and elongation of the welded seams of Examples 1 to 12 and Comparative Examples 1 to 7 of this application are detected.

[0107] According to the method described in Standard GB / T 2423.17-93, the corrosion conditions of the welds in Examples 1 to 12 and Comparative Examples 1 to 7 of this application after 120 hours of salt spray test were detected. The specific experimental photos are as Figure 5 shown.

[0108] The cross-sectional photo of the weld in Example 1 of this application is as Figure 1 shown, the cross-sectional photo of the weld in Example 10 is as Figure 2 shown, and the weld photos of Examples 3 to 8 are as Figure 4 shown. The obtained test results are shown in Table 1 below.

[0109] Table 1 Test Results of Examples 1 to 12 and Comparative Examples 1 to 7

[0110]

[0111]

[0112] It can be seen from the data in Table 1 that in Examples 1 to 12 of this application, specific welding wires and welding processes were used to weld the composite plates of this application, and the mechanical properties and corrosion resistance of the obtained welds are very excellent, significantly better than the welding processes of Comparative Examples 1 to 7.

[0113] From the data comparison of Examples 1 to 12, and Comparative Examples 1, 2, and 7 in Table 1, it can be seen that this application uses laser-arc hybrid welding and a welding wire with a specific ratio, and the weld performance is extremely excellent; using the welding wire of this application and welding the obtained weld with arc welding, or using other welding wires for welding, the performance of the obtained welds is significantly reduced compared with this application. The weld part of the base material of the weld obtained in Example 1 of this application was detected by electron microscopy, and the obtained results are as Figure 3 shown, and its metallographic structure is mainly acicular ferrite and supplemented by austenite, and the performance is significantly better. In addition, precise preheating treatment can also effectively improve the welding quality and stability.

[0114] From the data comparison of Examples 1 to 12, and Comparative Examples 3 to 6 in Table 1, it can be seen that the welding parameters of this application need to be precisely controlled. If there are deviations in the welding parameters, the performance of the welds will decrease significantly. The applicant speculates that laser power deviation will cause problems in keyhole welding; wire feeding speed deviation will cause problems in arc welding build-up; and welding speed deviation will cause the weld temperature to be too high or the welding quality to be insufficient, thereby affecting the welding quality.

[0115] From the data comparison of Examples 1 to 12 in Table 1, it can be seen that after optimizing the ratio of the welding wire and further optimizing the welding parameters in this application, the weld quality is significantly better. In addition, after controlling the welding current and precisely controlling the interlayer temperature in this application, the welding quality can be further significantly improved.

[0116] To further improve the welding quality, the applicant also studied the heat treatment after welding. The following are Examples 13 to 17 of this application.

[0117] Example 13

[0118] The difference between this example and Example 12 lies in the different heat treatment steps after welding.

[0119] The heat treatment steps of this example are as follows:

[0120] First, heat the welded composite plate in vacuum to 480 - 500 °C at a heating rate of 5 °C / min and hold for 30 min; then, cool it in the furnace to room temperature.

[0121] Example 14

[0122] The difference between this example and Example 12 lies in the different heat treatment steps after welding.

[0123] The heat treatment steps of this example are as follows:

[0124] First, heat the welded composite plate in vacuum to 520 - 540 °C at a heating rate of 15 °C / min and hold for 10 min; then, cool it in the furnace to room temperature.

[0125] Example 15

[0126] The difference between this example and Example 12 lies in the different heat treatment steps after welding.

[0127] The heat treatment steps of this example are as follows:

[0128] First, heat the welded composite plate in vacuum to 500 - 520 °C at a heating rate of 8 °C / min and hold for 25 min; then, cool it in the furnace to room temperature.

[0129] Example 16

[0130] The difference between this example and Example 12 lies in the different heat treatment steps after welding.

[0131] The heat treatment steps of this example are as follows:

[0132] First, heat the welded composite plate in vacuum to 500 - 520 °C at a heating rate of 12 °C / min and hold for 20 min; then, cool it in the furnace to room temperature.

[0133] Example 17

[0134] The difference between this example and Example 12 lies in the heat treatment step after welding.

[0135] The heat treatment steps of this example are as follows:

[0136] First, the welded composite plate is vacuum heated to 500 - 520 °C at a heating rate of 10 °C / min and held for 25 min; then, it is cooled to room temperature in the furnace.

[0137] Perform the same performance tests on the welds of the composite plates welded in Examples 13 - 17 of this application. The test results are shown in Table 2 below.

[0138] Table 2 Test Results of Examples 13 - 17

[0139] Tensile strength (MPa) Yield strength (MPa) Elongation rate (%) Weld corrosion Example 13 603.6 428.2 28.1 No corrosion Example 14 601.8 426.9 28.0 No corrosion Example 15 606.4 429.8 28.2 No corrosion Example 16 605.9 429.1 28.2 No corrosion Example 17 607.2 430.8 28.3 No corrosion

[0140] It can be seen from the data in Table 2 that after adopting the specific heat treatment steps of this application, the welding quality can be further significantly improved. In addition, after experimental research by the applicant, it is found that by optimizing the heat treatment parameters and adopting the heat treatment parameters of heating the welded composite plate to 500 - 520 °C at a heating rate of 8 - 12 °C / min and holding for 20 - 25 min, the welding quality can be further improved.

[0141] In addition to having high stability and welding quality for the welding of DH36 + S31254 composite plates, this application also has high stability and welding quality for the welding of S31254 + DH36 + S31254 composite plates. For composite plates with different thicknesses, this application only needs to select an appropriate weld width and at the same time select a wire with a matching diameter.

[0142] The above are all preferred embodiments of this application. The protection scope of this application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A composite plate welding method, characterized in that: Welding using laser arc hybrid welding equipment includes the following steps: S1. Pre-treat the welding joints of the composite plate to be welded to ensure that the joints are clean; S2, preheating the composite plate to be welded after the pretreatment in step S1; S3, fixing the composite plate to be welded after preheating in step S2, so that a weld gap of 1 to 10 mm wide is reserved at the weld joint; S4, start the laser arc hybrid welding equipment to weld the composite plate to be welded after being fixed in step S3, the welding parameters are: laser power 3.6-4.4KW, wire feeding speed 3.8-4.6m / min, welding speed 1.90-2.40m / min; The chemical components of the welding wire are as follows: carbon 0.020-0.024%, manganese 0.14-0.18%, silicon 0.38-0.52%, chromium 20.45-21.35%, nickel 9.6-10.0%, molybdenum 0.42-0.48%, copper 0.12-0.18%, cobalt 0.1-0.5%, nitrogen 0.04-0.06%, and the remainder is iron and unavoidable impurities.

2. The composite plate welding method according to claim 1, characterized in that: In the step S1, the pretreatment includes grinding the burrs on the welding joint and cleaning the welding joint.

3. The composite plate welding method according to claim 1, characterized in that: In step S2, the preheating temperature is 120-150°C.

4. The composite plate welding method according to claim 3, characterized in that: In step S2, the preheating time is 30 to 45 minutes.

5. The composite plate welding method according to claim 1, characterized in that: In step S4, the welding parameters are: laser power 4.0-4.2 kW, wire feeding speed 4.0-4.2 m / min, welding speed 2.00-2.10 m / min.

6. The composite plate welding method according to claim 1, characterized in that: In step S4, the welding current is 120A and the welding voltage is 12V.

7. The composite plate welding method according to claim 1, characterized in that: In step S4, the interlayer temperature is controlled at 130-150°C.

8. The composite plate welding method according to claim 1, characterized in that: After step S4, the method further includes the steps of grinding and heat treating the weld.

9. The composite plate welding method according to claim 8, characterized in that: The heat treatment comprises the following steps: first, vacuum heating the welded composite plate to 480-540° C. and keeping the temperature for 10-30 minutes; and then, cooling the furnace to room temperature.

10. The composite plate welding method according to claim 9, characterized in that: The heating rate is controlled at 8-12°C / min.

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