Electric arc additive manufacturing method of underwater local dry method layered composite material

Abstract

According to the electric arc additive manufacturing method for the underwater local dry method layered composite material, through additive section design and additive flat belt and additive wire welding process design, in the electric arc additive process, only the additive flat belt and the base body need to be connected in a fusion mode for deposited metal, the deposition amount of the additive deposited metal is greatly reduced, and the production efficiency is improved. The additive material efficiency is improved, the hydrogen embrittlement sensitivity of the additive material structure is effectively reduced, the additive material structure has the layered distribution structure characteristic, namely, an electric arc additive material deposition layer and additive material flat belt solid phase layer alternating structure, and the structure can remarkably improve the comprehensive performance of an additive material body.

Description

Technical Field

[0001] The invention belongs to the field of laser welding, and in particular relates to an arc additive manufacturing method for underwater local dry layered composite materials. Background Art

[0002] Underwater welding and additive technology are mainly used in the assembly and maintenance of marine engineering and large underwater facilities. At present, underwater welding and additive technology are mainly divided into wet method, dry method and partial dry method. The partial dry method combines the advantages of both wet method and dry method. It is a relatively advanced welding method with good application prospects. The partial dry method maintains a relatively dry state in the local area by installing a sealed drainage cover in the weld or additive area. This process has better welding quality and safety.

[0003] Chinese patent application CN 113618195 B discloses an underwater all-position local dry pulse MIG welding method. The system has a local strong drainage function, can provide a dry space for underwater welding, and the welding space airflow field is stable, with wide process adaptability. Its shortcomings are that the equipment structure of the patent is complex and the process adaptability is poor.

[0004] Chinese patent application CN 116532796 A discloses an underwater local dry laser wire welding system and method. After the underwater local dry welding is completed, the laser beam is used to remelt the weld to improve the weld surface structure and optimize the weld forming performance. Its disadvantage is that the laser is used to process the weld, and the laser's rapid heating and cooling process characteristics easily lead to high-hardness hardened structures, increasing the risk of weld cracking.

[0005] Chinese patent application CN 104942487A discloses an underwater local dry welding device and method for titanium alloy and other materials, which uses a microwave radiator to emit microwaves to oscillate and heat the water remaining on the titanium alloy plate, so that the water temperature rises to gasification, thereby making the weld surface water-free. Its disadvantage is that water vapor still exists in the welding environment, and hydrogen atoms will dissolve into the solidified metal of the weld during the welding process, increasing the risk of hydrogen-induced cracking.

[0006] However, the device structure of the above patent is relatively complex and has poor process adaptability. Moreover, during the welding or additive process, a large amount of wire needs to be melted to complete the welding connection work and the additive repair work. However, during underwater welding and additive processes, a small amount of water remains on the surface of the weld after drainage, which is prone to porosity defects; the lower temperature underwater causes a rapid cooling effect in the weld or additive area, which is prone to high-hardness hardened structures; in addition, the humidity of the underwater welding environment is high, and water vapor will be reduced to hydrogen under the influence of high temperatures of welding and additives, and dissolved into the solidified metal. When a large number of hydrogen atoms gather inside the metal, hydrogen embrittlement occurs. Summary of the invention

[0007] The object of the present invention is to overcome the above-mentioned problems and shortcomings and to provide an arc additive manufacturing method for underwater local dry layered composite materials that utilizes an arc additive manufacturing process for additive repair, which can greatly reduce the deposition amount of additive deposited metal, improve additive efficiency, effectively reduce the hydrogen embrittlement sensitivity of the additive structure, and improve the mechanical properties of the additive body.

[0008] The object of the invention is achieved in this way:

[0009] An underwater local dry arc additive manufacturing method for layered composite materials, mainly comprising:

[0010] (1) Additive cross-section design:

[0011] The cross-sectional shape of the additive flat strip is a symmetrical convex hexagon composed of a rectangle and an isosceles trapezoid, the lower base of the isosceles trapezoid is the same length as the rectangle, W:h:L=(3.5-6.5):1:(1.5-2.5), W is the length of the rectangle, h is the width of the rectangle, L is the upper base of the isosceles trapezoid, and the angle α between the hypotenuse of the isosceles trapezoid and the upper base of the isosceles trapezoid is 30°-55°; the cross-sectional shape of the additive wire is circular, with a diameter of 0.8-1.6 mm;

[0012] Furthermore, the chemical composition of the additive flat strip is as follows by mass percentage: C: 0.05% to 0.15%, Si: 0.3% to 1.5%, Mn: 0.5% to 1.5%, S≤0.02%, P≤0.02%, Cr: 0.2% to 0.6%, Ni: 0.5% to 4.0%, Mo: 0.3% to 1.0%, Ti: 0.02% to 0.08%, and the balance is Fe and unavoidable impurities. Preferably, the chemical composition range of the additive flat strip is the same as that of the round wire.

[0013] Furthermore, the additive flat strip is an extruded material, and the additive wire is a cold-drawn wire.

[0014] Furthermore; the tensile strength of the additive components produced by the arc additive manufacturing method of underwater local dry layered composite materials is greater than ≥500MPa, the elongation is ≥20%, the impact energy is ≥90J (KV2) at -40℃~0℃, and the residual stress is ≤100MPa.

[0015] The reasons for designing the additive flat strip component of the present invention are as follows:

[0016] The C content ensures that the deposited metal has a high strength. A C content higher than 0.2% will seriously deteriorate the weldability of the deposited metal, and a C content lower than 0.05% will not be able to ensure the strength requirements of the deposited metal. The deposited metal ensures a certain C content and a certain Cr and Mo ratio to ensure that the deposited metal precipitates fine M2C carbides during the subsequent heating process, achieving the purpose of secondary strengthening; after comprehensive consideration, the preferred C content of the present invention is 0.05% to 0.15%; Mo: 0.3% to 1.0%, Cr: 0.2% to 0.6%.

[0017] The combined deoxidation of Si and Mn forms MnO·SiO2, which has a low melting point (about 1270°C) and a low density. It can condense into large pieces of slag in the molten pool and float out, achieving a good deoxidation effect. In addition, Mn will react with S to form MnS, which can reduce the tendency of thermal cracks caused by S. In order to ensure the deoxidation effect of the deposited metal, the Si content is not less than 0.3%, and the Mn content is not less than 0.5%. However, if the Si content is greater than 1.5%, it will cause solid solution hardening of the weld and an increase in the number of secondary phases, resulting in brittle welds. The preferred Si content of the present invention is 0.3% to 0.6%; the Mn content is 0.5% to 1.5%, and the deposited metal can obtain good comprehensive properties.

[0018] Ni: Ni content can improve the hardenability of steel, reduce the toughness-brittleness transition temperature and cleavage fracture tendency of the deposited metal, and improve the toughness of the deposited metal; adding Ni can increase the strength of the deposited metal without significantly reducing its toughness. A Ni content greater than 0.5% can ensure that the deposited metal has good impact toughness under low temperature conditions. After considering other elements, the preferred Ni content of the present invention is 0.5% to 4.0%.

[0019] Ti: A small amount of Ti is easy to form TiO inclusions during the additive process, which promotes nucleation in austenite grains and is beneficial to improving the toughness of the deposited metal. When Ti is greater than 0.1%, it will promote the formation of hard phases such as bainite and MA components in the weld structure, which will deteriorate the toughness of the deposited metal. After considering other elements, the preferred Ti content of the present invention is 0.02% to 0.08%.

[0020] (2) Create a water-proof environment: Use a drainage hood to isolate the additive area from the water around the work area, and after the water in the drainage hood is drained, introduce argon gas into the drainage hood as a protective gas to prevent the additive deposited metal from reacting with oxygen at high temperature to oxidize, thereby affecting the purity and performance of the additive deposited metal. In addition, argon gas can make the additive arc more stable, ensuring the continuity and uniformity of the additive process;

[0021] (3) The wound additive flat strip is placed above the substrate to be welded, and two metal-metal gas shielded welding guns are symmetrically distributed on both sides of the substrate. The inclination angle β of the metal-metal gas shielded welding gun is 20° to 40°, which is the angle between the welding gun and the horizontal line. The additive wire welding current is 100 to 300 A, the additive wire welding voltage is 12 to 30 V, the welding gun moving speed is 3 to 10 mm / s, the extension length of the additive wire is 15 to 35 mm, and the additive shielding gas is 80% to 90% argon + 10% to 20% carbon dioxide;

[0022] During the additive welding process, the wire of the metallurgical arc welding melts, and the angle of the welding gun can be adjusted to fill the molten metal to the angle between the contact position of the additive flat strip and the substrate. The process parameters of the selected additive wire can ensure the depth of the deposited metal to form a good metallurgical bond between the additive flat strip and the substrate; preferably, after each additive process is completed and before the next additive process, the temperature of the additive flat strip is controlled to be 100-150°C to prepare for the next additive process;

[0023] (4) Keeping the angle of the metal-metal gas shielded welding gun unchanged, the height of one layer of the additive flat strip is raised upwards, and the additive flat strip is placed above the first layer of flat strip, and step (3) is repeated until all additive welding work is completed.

[0024] The beneficial effects of the present invention are:

[0025] 1) During the arc additive process, the deposited metal only needs to fuse the additive flat strip with the substrate, which greatly reduces the deposition amount of additive deposited metal and improves the additive efficiency.

[0026] 2) During the arc additive process, the two gas shielded welding guns are symmetrically distributed on both sides of the substrate, and the amount of deposited metal is small, which greatly reduces the residual stress of the additive structure and makes the residual stress distribution more uniform. The reduction in the amount of deposited metal results in fewer hydrogen atoms dissolving into the solidified metal of the weld during the additive process, reducing the risk of hydrogen-induced cracking.

[0027] 3) The additive structure presents a layered distribution structural feature, that is, the arc additive deposition layer and the additive flat strip solid phase layer are alternating in structure. The additive structure presents a layered distribution structural feature, that is, the cast deposition layer and the extruded solid phase layer are alternating in meshing structure. The cast deposition layer ensures the forming and connection of the additive body, and the existence of the extruded solid phase layer is beneficial to improving the comprehensive performance of the additive body. The layered distribution structural feature can significantly improve the comprehensive performance of the additive body. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the additive repair work of the present invention.

[0029] Figure 2 It is a schematic diagram of the tilt angle of the metal electrode gas shielded welding gun of the present invention.

[0030] Figure 3 It is a schematic diagram of the additive flat belt structure of the present invention.

[0031] Figure 4 This is an enlarged view of the organizational characteristics of the layered structured additive body.

[0032] Figure 5 This is a microstructure diagram of region a of the interface between the deposited layer of the layered additive body and the flat strip solid phase layer in Example 1 of the present invention.

[0033] Figure 6 This is the microstructure diagram of the solid phase layer b area of ​​the flat strip of the layered structure additive body in Example 1 of the present invention.

[0034] Figure 7 This is the microstructure diagram of region c of the deposition layer of the layered structure additive body in Example 1 of the present invention.

[0035] In the figure, 1 is a substrate, 2 is a metal-metal gas shielded welding gun, 3 is an additive wire, 4 is an arc additive deposition layer, 5 is an additive flat strip solid phase layer, 6 is an additive flat strip, and 7 is an isolation cover. DETAILED DESCRIPTION

[0036] The present invention will be further described below by way of examples.

[0037] Example 1: Additive Manufacturing of Underwater AH32 Marine Steel

[0038] According to the material composition of AH32, the composition (mass fraction %) of the additive flat strip and round wire is designed to be C: 0.1, Si: 1.3, Mn: 1.3, S≤0.02, P≤0.02, Cr: 0.2, Ni: 0.8, Mo: 0.4, Ti: 0.03, and the balance is Fe.

[0039] The additive flat belt is processed by hot extrusion process. The cross-sectional shape of the additive flat belt is a symmetrical convex hexagon composed of a rectangle and an isosceles trapezoid. The lower base of the isosceles trapezoid is the same length as the rectangle, W:h:L=3.625:1:2, W is the length of the rectangle, h is the width of the rectangle, and L is the upper base of the isosceles trapezoid, specifically h=8mm, W=29mm, L=16mm, and the angle α between the hypotenuse of the isosceles trapezoid and the upper base of the isosceles trapezoid is 45°. After the additive flat belt is processed, it is wound on a disk;

[0040] The round additive wire is processed by cold drawing process. The diameter of the round additive wire is 1.2mm. After the additive wire is processed, it is wound into a coil.

[0041] 2) A drainage hood is used to isolate the additive area from the surrounding water, and after the water in the drainage hood is drained, argon gas is introduced into the drainage hood as a protective gas.

[0042] 3) Place the coiled additive flat belt above the substrate, adjust the inclination angle β of the metal-metal gas shielded welding gun to 25°, and distribute the two metal-metal gas shielded welding guns symmetrically on both sides of the substrate. The arc additive process parameters are as follows: current is 180A, voltage is 13V, moving speed is 8mm / s, the extension length of the additive wire is 25mm, and the additive shielding gas is 80% argon + 20% carbon dioxide.

[0043] Turn on the arc additive device and carry out additive work. The wire of the metallurgical electrode gas shielded welding is melted, and the molten metal is filled to the angle between the contact position of the additive flat strip and the substrate, so that the additive flat strip and the substrate form a good metallurgical bond. After the first layer of additive is completed, the interlayer temperature is controlled to be 120°C.

[0044] 4) Keep the two consumable electrode gas shielded welding guns at the same angle, raise the height of one layer of additive flat strip, place the additive flat strip on top of the first layer of flat strip, and perform subsequent additive work according to the additive process in 3) until 50 mm, a total of 5 layers of arc additive work are completed.

[0045] The tensile strength of arc additive manufacturing components made of AH32 marine steel layered composite materials is 515MPa, the elongation is 24%, the impact energy is 125J (0℃), and the residual stress is 55MPa. Figure 5 This is a microstructure diagram of the interface a between the deposited layer of the layered structure additive body and the flat belt solid phase layer in Example 1 of the present invention, see Figure 6 This is the microstructure diagram of the solid phase layer b of the flat belt of the layered structure additive body in Example 1 of the present invention. Figure 7 This is the microstructure diagram of region c of the deposition layer of the layered structure additive body in Example 1 of the present invention.

[0046] Example 2: Additive Manufacturing of Underwater DH36 Marine Steel

[0047] 1) According to the material composition of DH36 matrix, the composition (mass fraction %) of additive flat strip and round wire is designed: C: 0.08, Si: 1.0, Mn: 1.2, S ≤ 0.02, P ≤ 0.02, Cr: 0.5, Ni: 1.5, Mo: 0.5, Ti: 0.05, and the balance is Fe.

[0048] The additive flat belt is processed by hot extrusion process. The cross-sectional shape of the additive flat belt is a symmetrical convex hexagon composed of a rectangle and an isosceles trapezoid. The lower base of the isosceles trapezoid is the same length as the rectangle, W:h:L=5:1:2.3, W is the length of the rectangle, h is the width of the rectangle, and L is the upper base of the isosceles trapezoid, specifically h=3mm, W=15mm, L=7mm, and the angle α between the hypotenuse of the isosceles trapezoid and the upper base of the isosceles trapezoid is 55°. After the additive flat belt is processed, it is wound on a disk;

[0049] The round additive wire is processed by cold drawing process. The diameter of the round additive wire is 1.2mm. After the additive wire is processed, it is wound into a coil.

[0050] 2) A drainage hood is used to isolate the additive area from the surrounding water, and after the water in the drainage hood is drained, argon gas is introduced into the drainage hood as a protective gas.

[0051] 3) Place the coiled additive flat belt above the substrate, adjust the inclination angle β of the metal-metal gas shielded welding gun to 30°, and distribute the two metal-metal gas shielded welding guns symmetrically on both sides of the substrate. The arc additive process parameters are as follows: current is 210A, voltage is 16V, moving speed is 5mm / s, the extension length of the additive wire is 35mm, and the additive shielding gas is 80% argon + 20% carbon dioxide.

[0052] Turn on the arc additive device and perform additive work. The wire of the metallurgical electrode gas shielded welding is melted, and the molten metal is filled to the angle between the contact position of the additive flat strip and the substrate, so that the additive flat strip and the substrate form a good metallurgical bond. After the first layer of additive is completed, the interlayer temperature is controlled to be 150°C.

[0053] 4) Keep the two consumable electrode gas shielded welding guns at the same angle, raise the height of one layer of additive flat strip, place the additive flat strip on top of the first layer of flat strip, and perform subsequent additive work according to the additive process in 3) until all arc additive work of 60 mm and a total of 15 layers is completed.

[0054] The arc additively manufactured components of DH36 marine steel with layered composite materials have a tensile strength of 535MPa, an elongation of 25%, an impact energy of 115J (-20℃), and a residual stress of 75MPa.

[0055] Example 3: Additive Manufacturing of Underwater EH36 Marine Steel

[0056] 2) According to the material composition of the EH36 matrix, the composition (mass fraction %) of the additive flat strip and round wire is designed: C: 0.07, Si: 0.8, Mn: 1.1, S ≤ 0.02, P ≤ 0.02, Cr: 0.3, Ni: 3.5, Mo: 0.7, Ti: 0.05, and the balance is Fe.

[0057] The additive flat belt is processed by hot extrusion process. The cross-sectional shape of the additive flat belt is a symmetrical convex hexagon composed of a rectangle and an isosceles trapezoid. The lower base of the isosceles trapezoid is the same length as the rectangle, W:h:L=3.6:1:1.8, W is the length of the rectangle, h is the width of the rectangle, L is the upper base of the isosceles trapezoid, specifically h=5mm, W=18mm, L=9mm, the angle between the hypotenuse of the isosceles trapezoid and the upper base of the isosceles trapezoid α=45°, and the additive flat belt is wound on the disk after processing;

[0058] The round additive wire is processed by cold drawing process. The diameter of the round additive wire is 1.0 mm. After the additive wire is processed, it is wound into a coil.

[0059] 2) A drainage hood is used to isolate the additive area from the surrounding water, and after the water in the drainage hood is drained, argon gas is introduced into the drainage hood as a protective gas.

[0060] 3) Place the coiled additive flat belt above the substrate, adjust the inclination angle β of the metal-metal gas shielded welding gun to 35°, and distribute the two metal-metal gas shielded welding guns symmetrically on both sides of the substrate. The arc additive process parameters are as follows: current is 250A, voltage is 18V, moving speed is 5mm / s, the extension length of the additive wire is 30mm, and the additive shielding gas is 90% argon + 10% carbon dioxide.

[0061] The arc additive device is turned on and additive work is carried out. The wire of the consumable gas shielded welding is melted, and the molten metal is filled to the angle between the contact position of the additive flat strip and the substrate, so that the additive flat strip and the substrate form a good metallurgical bond. After the first layer of additive is completed, the interlayer temperature is controlled to be 130°C.

[0062] 5) Keep the two consumable electrode gas shielded welding guns at the same angle, raise the height of one layer of additive flat strip upwards, place the additive flat strip above the first layer of flat strip, and perform subsequent additive work according to the additive process in 3) until all arc additive work of 100 mm and a total of 17 layers is completed.

[0063] The arc additively manufactured components of EH36 marine steel with layered composite materials have a tensile strength of 575MPa, an elongation of 26%, an impact energy of 132J (-40°C), and a residual stress of 80MPa.

[0064] The tensile strength of the additive components produced by the arc additive manufacturing method of underwater local dry layered composite materials is greater than or equal to 500MPa, the elongation is ≥20%, the impact energy is ≥90J (KV2) at -40℃ to 0℃, and the residual stress is ≤100MPa.

[0065] In order to describe the present invention, the present invention is appropriately and fully illustrated by the examples in the above. The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made should be included in the protection scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. An underwater local dry arc additive manufacturing method for layered composite materials, characterized in that: (1) Additive cross-section design: The cross-sectional shape of the additive flat strip is a symmetrical convex hexagon composed of a rectangle and an isosceles trapezoid, the lower base of the isosceles trapezoid is the same length as the rectangle, W:h:L=(3.5-6.5):1:(1.5-2.5); wherein W is the length of the rectangle, h is the width of the rectangle, L is the upper base of the isosceles trapezoid, and the angle α between the hypotenuse of the isosceles trapezoid and the upper base of the isosceles trapezoid is 30°-55°; the cross-sectional shape of the additive wire is circular, with a diameter of 0.8-1.6 mm; (2) Create a water-proof environment: Use a drainage hood to isolate the water around the additive area and the work area. After the water in the drainage hood is drained, argon gas is introduced into the drainage hood as a protective gas. (3) Two gas shielded welding guns are symmetrically arranged on both sides of the substrate, and the inclination angle β of the gas shielded welding gun is 20° to 40°, which is the angle between the welding gun and the horizontal line. The welding current of the additive wire is 100 to 300 A, the welding voltage of the additive wire is 12 to 30 V, the moving speed of the welding gun is 3 to 10 mm / s, the extension length of the additive wire is 15 to 35 mm, and the additive shielding gas is 80% to 90% argon + 10% to 20% carbon dioxide; (4) Keeping the angle of the metal-metal gas shielded welding gun unchanged, the height of one layer of the additive flat strip is raised upwards, and the additive flat strip is placed above the first layer of flat strip. Repeat (3) until all additive welding work is completed.

2. The arc additive manufacturing method of underwater local dry layered composite materials according to claim 1, characterized in that: The chemical composition of the additive flat strip is as follows by mass percentage: C: 0.05% ~ 0.15%, Si: 0.3% ~ 1.5%, Mn: 0.5% ~ 1.5%, S ≤ 0.02%, P ≤ 0.02%, Cr: 0.2% ~ 0.6%, Ni: 0.5% ~ 4.0%, Mo: 0.3% ~ 1.0%, Ti: 0.02% ~ 0.08%, and the balance is Fe and unavoidable impurities.

3. The arc additive manufacturing method of underwater local dry layered composite materials according to claim 1, characterized in that: Additive flat ribbons have the same chemical composition range as round wires.

4. The arc additive manufacturing method of underwater local dry layered composite materials according to claim 1, characterized in that: Additive flat strips are extruded materials, and additive wires are cold-drawn wires.

5. The arc additive manufacturing method of underwater local dry layered composite materials according to claim 1, characterized in that: The tensile strength of the additive components produced by the arc additive manufacturing method of underwater local dry layered composite materials is greater than or equal to 500MPa, the elongation is ≥20%, the impact energy is ≥90J at -40℃ to 0℃, and the residual stress is ≤100MPa.

6. The arc additive manufacturing method of underwater local dry layered composite materials according to claim 1, characterized in that: After the step (3) of adding material, the temperature of the additive flat belt is controlled to be 100-150°C before adding the next layer.

7. The arc additive manufacturing method of underwater local dry layered composite materials according to claim 1, characterized in that: The internal structure of the additive component produced by the arc additive manufacturing method of underwater local dry layered composite materials is layered, and the layer distribution is an alternating structure of arc additive deposition layers and additive flat strip solid phase layers.

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