A welding material and a welding method for submerged arc automatic single-sided welding of copper backing

Abstract

This invention discloses a welding material and method for automatic submerged arc welding of copper backing, comprising: welding wire, surface flux, and bottom flux. The welding wire comprises: C, Si, Mn, Cr, Ni, S, P, Mo, and Cu, with the balance being Fe powder. The surface and bottom fluxes comprise: SiO2, MgO, MnO, TiO2, Al2O3, Ca, S, P, impurities, Fe2O3, and water. The mass ratio of welding wire, surface flux, and bottom flux is 0.9-1.1:1.1-1.5:0.5-0.9. This invention is applied to automatic submerged arc welding of copper backing, and is particularly suitable for welding hull structures in the cryogenic areas of LNG carrier cargo holds. Its welding process performance meets the working requirements of the cryogenic environment in this area, while also reducing welding material costs. The mechanical properties of the deposited metal meet the requirements of the 4Y grade of the China Classification Society's "Materials and Welding Specifications".

Description

Technical Field

[0001] This invention belongs to the field of shipbuilding, and specifically relates to a welding material and welding method for automatic single-sided submerged arc welding of copper backing. Background Technology

[0002] Liquefied natural gas (LNG) carriers are the primary means of transporting natural gas globally and play a crucial role in the LNG energy trade. While China's LNG carrier construction has reached a mature stage, certain challenges remain in ensuring the welding performance of the cargo hold hull structure at low temperatures. Flux Cooper Backing (FCB) submerged arc automatic single-sided welding, a high-heat welding method, struggles to guarantee weld performance at low temperatures when welding cargo hold hull structures using conventional welding materials. Furthermore, the welding materials used in China's FCB process are primarily imported, significantly increasing production costs. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a welding material and welding method for automatic single-sided submerged arc welding of copper backings. This method is applied to the welding of hull structures in the cargo hold area of ​​LNG ships, ensuring welding process performance in this area under low-temperature conditions, improving the manufacturing capabilities of domestic welding materials, and reducing production costs.

[0004] The objective of this invention is achieved through the following technical solution: a welding material for automatic single-sided submerged arc welding of copper backing, comprising: welding wire, surface flux, and bottom flux.

[0005] The welding wire composition includes: C, Si, Mn, Cr, Ni, S, P, Mo, Cu, with the balance being Fe powder.

[0006] The surface flux and the bottom flux consist of: SiO2, MgO, MnO, TiO2, Al2O3, Ca, S, P, impurities, Fe2O3 and water.

[0007] Preferably, the mass ratio of welding wire, surface flux and bottom flux is 0.9-1.1:1.1-1.5:0.5-0.9.

[0008] Preferably, the mass percentage of each component in the welding wire is as follows:

[0009] C: 0.08%-0.12%;

[0010] Si: 0.01%-0.3%;

[0011] Mn: 1.5%-2.0%;

[0012] Cr: 0.01%-0.2%;

[0013] Ni: 0.03%-0.50%;

[0014] S: 0.005%-0.025%;

[0015] P: 0.005%-0.025%;

[0016] Mo: 0.01%-0.025%;

[0017] Cu: 0.01%-0.35%.

[0018] Preferably, the mass percentage of each component in the surface flux is:

[0019] SiO2: 10%-20%;

[0020] MgO: 15%-35%;

[0021] MnO: 1%-5%;

[0022] TiO2: 5%-15%;

[0023] Al2O3: 5%-20%;

[0024] Ca: 5%-20%;

[0025] S: 0.01%-0.04%;

[0026] P: 0.01%-0.04%;

[0027] Impurities: 0.01%-0.025%;

[0028] Fe2O3: 15%-40%;

[0029] Water: 0.01%-0.1%.

[0030] The mass percentage of each component in the bottom flux is as follows:

[0031] SiO2: 15%-40%;

[0032] MgO: 20%-35%;

[0033] MnO: 1%-5%;

[0034] TiO2: 1%-5%;

[0035] Al2O3: 5%-15%;

[0036] Ca: 5%-15%;

[0037] S: 0.01%-0.025%;

[0038] P: 0.01%-0.025%;

[0039] Impurities: 0.01%-0.025%;

[0040] Fe2O3: 1%-10%;

[0041] Water: 0.01%-0.1%.

[0042] Preferably, the surface flux and the bottom flux are spherical particles with a particle size of 10-60 mesh.

[0043] In addition to providing a welding material for automatic single-sided submerged arc welding of copper backing, this invention further provides a method for performing automatic single-sided submerged arc welding of copper backing using the above-mentioned material, specifically including the following steps:

[0044] Step 1: Determine the type of welding bevel;

[0045] Step 2: Apply the base layer of flux;

[0046] Step 3: Inflate the air hose to ensure the copper gasket is in close contact with the workpiece;

[0047] Step 4: Adjust the wire spacing and extension length;

[0048] Step 5: Weld using the principle of submerged arc welding to achieve efficient welding with single-sided welding and double-sided forming.

[0049] Preferably, in step 1, the welding groove is a Y-shaped groove butt joint with a groove gap of 0mm-1mm. The groove angle α and the blunt edge P are determined according to the plate thickness of the workpiece being welded. When the plate thickness t satisfies 8mm≤t<19mm, α is 57°-63° and P is 2.5mm-4.5mm; 19mm≤t<24mm, α is 47°-53° and P is 2.5mm-4.5mm; 24mm≤t<31mm, α is 47°-53° and P is 4.5mm-6.5mm; 31mm≤t<38mm, α is 42°-45° and P is 5.5mm-7.5mm.

[0050] Preferably, in step 2, the thickness of the bottom layer weld is 4mm-6mm and the width is 100mm-120mm.

[0051] Preferably, in step 3, compressed air is filled into the air hose at a pressure of 0.1 MPa to 0.22 MPa to ensure that the gasket is tightly attached to the workpiece. In order to ensure that the bottom flux is tightly attached to the plate, it is necessary to use a hammer to evenly tap within 100 mm on both sides of the joint on the surface of the steel plate.

[0052] Preferably, in step 4, the spacing and extension length of the welding wires must meet the following requirements: the spacing between electrode L and electrode T1 is 35mm, the spacing between electrode T1 and electrode T2 is 120mm, the extension lengths of electrodes L, T1, and T2 are 35mm, 45mm, and 55mm, respectively, and the angles between electrodes L, T1, and T2 and the vertical direction are 15°, 15°, and 5°, respectively.

[0053] Compared with the prior art, the present invention has the following advantages:

[0054] This invention provides a welding material and method for automatic single-sided submerged arc welding with copper backing, which is used for automatic single-sided submerged arc welding of steel plates with a thickness of 8mm-38mm using the FCB method. The mechanical properties of the weld metal meet the requirements of the 4Y grade of the China Classification Society's "Materials and Welding Specifications".

[0055] This invention breaks through the foreign technological monopoly in the field of FCB low-temperature welding materials and provides a welding material for automatic single-sided submerged arc welding of copper backing. It can meet the welding requirements of welding heat input greater than 100KJ / cm and welding speed of 60cm / min-90cm / min, and meets the welding performance in a low temperature environment of -40℃. It can be applied to the welding of hull structure in cargo hold area of ​​LNG ship.

[0056] When the welding material combination provided by this invention is used for FCB welding, the mechanical properties of the deposited metal meet the requirements of the 4Y grade of the China Classification Society's "Materials and Welding Specifications", with a yield strength greater than 305 MPa, a tensile strength of 490 MPa-660 MPa, an elongation greater than 22%, and an average impact energy greater than 34 J. At the same time, the cost of this invention is 30%-40% lower than that of imported similar welding materials. Attached Figure Description

[0057] Figure 1 This is a schematic diagram illustrating the structural principle of bevel welding in an embodiment of the present invention;

[0058] Figure 2 This is a schematic diagram of the bevel in an embodiment of the present invention;

[0059] Figure 3 This is a schematic diagram of the wire spacing and length in an embodiment of the present invention.

[0060] In the diagram, 1 is the welding wire; 2 is the surface flux; 3 is the bottom flux; 4 is the copper gasket; and 5 is the air hose. Detailed Implementation

[0061] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0062] The present invention provides a welding material for automatic single-sided submerged arc welding of copper backing, comprising: welding wire 1, surface flux 2 and bottom flux 3.

[0063] The welding wire 1 is composed of: C, Si, Mn, Cr, Ni, S, P, Mo, Cu, with the balance being Fe powder.

[0064] The surface flux 2 and the bottom flux 3 consist of: SiO2, MgO, MnO, TiO2, Al2O3, Ca, S, P, impurities, Fe2O3 and water.

[0065] In one embodiment of the present invention, the mass ratio of welding wire 1, surface flux 2 and bottom flux 3 is 0.9-1.1:1.1-1.5:0.5-0.9.

[0066] The mass percentages of each component in welding wire 1 are as follows:

[0067] C: 0.08%-0.12%;

[0068] Si: 0.01%-0.3%;

[0069] Mn: 1.5%-2.0%;

[0070] Cr: 0.01%-0.2%;

[0071] Ni: 0.03%-0.50%;

[0072] S: 0.005%-0.025%;

[0073] P: 0.005%-0.025%;

[0074] Mo: 0.01%-0.025%;

[0075] Cu: 0.01%-0.35%.

[0076] The mass percentages of each component in surface flux 2 are as follows:

[0077] SiO2: 10%-20%;

[0078] MgO: 15%-35%;

[0079] MnO: 1%-5%;

[0080] TiO2: 5%-15%;

[0081] Al2O3: 5%-20%;

[0082] Ca: 5%-20%;

[0083] S: 0.01%-0.04%;

[0084] P: 0.01%-0.04%;

[0085] Impurities: 0.01%-0.025%;

[0086] Fe2O3: 15%-40%;

[0087] Water: 0.01%-0.1%;

[0088] The mass percentages of each component in the bottom flux 3 are as follows:

[0089] SiO2: 15%-40%;

[0090] MgO: 20%-35%;

[0091] MnO: 1%-5%;

[0092] TiO2: 1%-5%;

[0093] Al2O3: 5%-15%;

[0094] Ca: 5%-15%;

[0095] S: 0.01%-0.025%;

[0096] P: 0.01%-0.025%;

[0097] Impurities: 0.01%-0.025%;

[0098] Fe2O3: 1%-10%;

[0099] Water: 0.01%-0.1%.

[0100] In the above embodiments, the surface flux 2 and the bottom flux 3 are spherical particles with a particle size of 10-60 mesh. As a further optimization of the above embodiments, the mass percentages of each component in the welding wire 1 are as follows: C: 0.12%-0.12%;

[0101] Si: 0.02%-0.2%; Mn: 1.7%-2.0%;

[0102] Cr: 0.01%-0.17%; Ni: 0.03%-0.50%;

[0103] S: 0.005%-0.02%;

[0104] P: 0.005%-0.02%;

[0105] Mo: 0.01%-0.02%;

[0106] Cu: 0.01%-0.28%; balance is Fe powder.

[0107] The mass percentages of each component in the surface flux are as follows:

[0108] SiO2: 10%-18%;

[0109] MgO: 15%-28%;

[0110] MnO: 1%-3%;

[0111] TiO2: 5%-12%; Al2O3: 7%-15%;

[0112] Ca: 5%-15%; S: 0.01%-0.02%;

[0113] P: 0.01%-0.02%;

[0114] Impurities: 0.015%-0.025%;

[0115] Fe2O3: 25%-40%;

[0116] Water: 0.01%-0.08%;

[0117] The mass percentages of each component in the bottom flux are as follows:

[0118] SiO2: 20%-40%;

[0119] MgO: 22%-32%;

[0120] MnO: 1%-4%; TiO2: 1%-3%;

[0121] Al2O3: 8%-15%;

[0122] Ca: 5%-12%;

[0123] S: 0.01%-0.02%;

[0124] P: 0.01%-0.02%;

[0125] Impurities: 0.015%-0.025%;

[0126] Fe2O3: 1%-8%;

[0127] Water: 0.01%-0.08%.

[0128] In addition to providing a welding material for automatic single-sided submerged arc welding of copper backing, the present invention further provides a method for performing automatic single-sided submerged arc welding of copper backing using the above material, specifically including the following steps:

[0129] Step 1: Determine the welding groove type:

[0130] The welding groove is a Y-shaped butt joint with a groove gap of 0mm-1mm. The groove angle α and the blunt edge P are determined according to the thickness of the workpiece. When the plate thickness t satisfies 8mm≤t<19mm, α is 57°-63° and P is 2.5mm-4.5mm; 19mm≤t<24mm, α is 47°-53° and P is 2.5mm-4.5mm; 24mm≤t<31mm, α is 47°-53° and P is 4.5mm-6.5mm; 31mm≤t<38mm, α is 42°-45° and P is 5.5mm-7.5mm.

[0131] Step 2, Apply the bottom layer of flux 3:

[0132] The thickness of the bottom layer weld is 4mm-6mm, and the width is 100mm-120mm.

[0133] Step 3: Inflate the air hose 5 to ensure the copper gasket 4 is tightly pressed against the workpiece.

[0134] Compressed air is introduced into the air hose at a pressure of 0.1 MPa to 0.22 MPa to ensure that the gasket is tightly attached to the workpiece. To ensure that the bottom flux 3 is tightly attached to the plate, it is necessary to tap the steel plate surface evenly with a hammer within a 100 mm range on both sides of the joint.

[0135] Step 4: Adjust the spacing and extension length of welding wire 1:

[0136] The spacing and extension length of welding wire 1 must meet the following requirements: the spacing between electrode L and electrode T1 is 35mm, the spacing between electrode T1 and electrode T2 is 120mm, the extension lengths of electrodes L, T1, and T2 are 35mm, 45mm, and 55mm respectively, and the angles between electrodes L, T1, and T2 and the vertical direction are 15°, 15°, and 5° respectively.

[0137] Step 5: Weld using the principle of submerged arc welding to achieve efficient welding with single-sided welding and double-sided forming.

[0138] The following example further illustrates the welding material and method for automatic single-sided submerged arc welding of copper backing provided in the technical solution of this invention:

[0139] In this embodiment, the mass ratio of welding wire 1, surface flux 2 and bottom flux 3 is 1:1.3:0.6.

[0140] The mass percentages of each component in welding wire 1 are as follows: C 0.12%, Si 0.047%, Mn 1.87%, Cr 0.05%, Ni 0.02%, S 0.006%, P 0.009%, Mo 0.01%, Cu 0.03%, with the balance being Fe powder;

[0141] The mass percentages of each component in surface flux 2 are as follows: SiO2 10.63%, MgO 17.88%, MnO 1.16%, TiO2 9.62%, Al2O3 7.94%, Ca 8.84%, S 0.01%, P 0.012%, impurities ≤0.02%, Fe2O3 38.2%, and water content 0.01%-0.08%.

[0142] The mass percentages of each component in the bottom flux 3 are as follows: SiO2 36.73%, MgO 29.74%, MnO 2.79%, TiO2 1.16%, Al2O3 11.20%, Ca 6.92%, S 0.018%, P 0.018%, impurities ≤0.02%, Fe2O3 3.2%, and water content 0.01%-0.08%.

[0143] In this embodiment, the particle size of the surface flux 2 and the bottom flux 3 is 10-60 mesh.

[0144] The specific steps for automatic single-sided submerged arc welding of copper backing using the welding materials described in this embodiment are as follows:

[0145] Step 1: Determine the welding groove type, such as... Figures 1 to 2 As shown, the bevel welding form in this embodiment is: Y-type bevel butt joint, bevel gap b is 0mm~1mm, plate thickness t is 20mm, bevel angle α is 47°~53°, and blunt edge P is 2.5mm~4.5mm;

[0146] Step 2: Use the flux laying automatic trolley to lay the bottom layer of flux. The thickness of the bottom layer of flux is 4mm to 6mm and the width is 100mm to 120mm.

[0147] Step 3: Inflate the air hose 5 to raise the copper gasket 4. The inflation pressure is 0.1Mpa~0.22Mpa. Make the copper gasket 4 fit tightly against the workpiece and make sure the weld is aligned with the center of the copper gasket 4. In order to make the bottom flux 3 fit tightly against the plate, it is necessary to use a hammer to tap evenly within 100mm on both sides of the joint on the steel plate surface.

[0148] Step 4: Adjust the spacing and extension length of welding wire 1; the spacing between electrode L and electrode T1 is 35mm, the spacing between electrode T1 and electrode T2 is 120mm, the extension lengths of electrodes L, T1, and T2 are 35mm, 45mm, and 55mm respectively, and the angles between electrodes L, T1, and T2 and the vertical direction are 15°, 15°, and 5° respectively. Figure 3 As shown.

[0149] Step 5: Welding is performed using the principle of submerged arc welding to achieve efficient welding of single-sided welding and double-sided forming of the test plate.

[0150] In this embodiment, the test plate is made of high-strength ship hull structural steel grade: DH36, thickness: 20mm, and its chemical composition is shown in Table 1.

[0151] Table 1 Chemical Composition of DH36 High-Strength Ship Hull Structural Steel

[0152]

[0153] Welding specifications are shown in Table 2.

[0154] Table 2 Welding Specification Parameters

[0155]

[0156] The mechanical properties of the weld metal were tested, including the tensile strength, yield strength, elongation, and low-temperature impact energy at -40℃. The results are shown in Table 3.

[0157] Table 3 Mechanical properties of weld metal

[0158]

[0159] As shown in Table 3, the welding materials provided in this embodiment can produce weld metal with excellent mechanical properties when applied to FCB technology welding. The mechanical properties of the weld metal meet the requirements of the 4Y grade of the China Classification Society's "Materials and Welding Specifications". Its welding process performance can meet the low-temperature environment requirements of the hull structure in the cargo hold area of ​​LNG ships.

[0160] The composition design of the welding material provided in this invention is obtained through extensive theoretical analysis and experimental optimization. By adjusting the basicity of the flux, the weld can be guaranteed to have the optimal oxygen content. Appropriately increasing the basicity value can improve the strength, toughness, and acicular ferrite content of the deposited metal. Reasonable selection of alloy system can change the phase transformation during the weld crystallization process, and obtain a large amount of fine acicular ferrite, thereby improving strength and toughness.

[0161] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A copper-backed submerged arc automatic single-sided welding material, characterized in that: The welding materials include: welding wire (1), surface flux (2) and bottom flux (3); The welding wire (1) comprises: C, Si, Mn, Cr, Ni, S, P, Mo, Cu, with the balance being Fe powder; The surface flux (2) and the bottom flux (3) consist of: SiO2, MgO, MnO, TiO2, Al2O3, Ca, S, P, impurities, Fe2O3 and water; The mass percentage of each component in the welding wire (1) is as follows: C：0.08%-0.12%； Si: 0.01%-0.3%; Mn: 1.5%-2.0%; Cr：0.01%-0.2%； Ni: 0.03%-0.50%; S：0.005%-0.025%； P：0.005%-0.025%； Mo: 0.01%-0.025%; Cu: 0.01%-0.35%; The mass percentage of each component in the surface flux (2) is as follows: SiO2: 10%-20%; MgO: 15%-35%; MnO: 1%-5%; TiO2: 5%-15%; Al2O3: 5%-20%; Ca: 5%-20%; S：0.01%-0.04%； P：0.01%-0.04%； Impurities: 0.01%-0.025%; Fe2O3: 15%-40%; Water: 0.01%-0.1%; The mass percentage of each component in the underlying flux (3) is as follows: SiO2: 15%-40%; MgO: 20%-35%; MnO: 1%-5%; TiO2: 1%-5%; Al2O3: 5%-15%; Ca: 5%-15%; S：0.01%-0.025%； P：0.01%-0.025%； Impurities: 0.01%-0.025%; Fe2O3: 1%-10%; Water: 0.01%-0.1%.

2. The copper-backed submerged arc automatic single-sided welding material as described in claim 1, characterized in that: The mass ratio of the welding wire (1), surface flux (2) and bottom flux (3) is 0.9-1.1:1.1-1.5:0.5-0.

9.

3. The copper-backed submerged arc automatic single-sided welding material as described in claim 1, characterized in that: The surface flux (2) and the bottom flux (3) are spherical particles with a particle size of 10-60 mesh.

4. An automatic single-sided submerged arc welding method for copper backing, characterized in that: The method for automatic single-sided submerged arc welding of copper backing using the welding material described in any one of claims 1-3 includes the following steps: Step 1: Determine the type of welding bevel; The welding groove is a Y-type bevel butt joint with a groove gap of 0mm-1mm. The groove angle α and the blunt edge P are determined according to the thickness of the workpiece. When the plate thickness t satisfies 8mm≤t<19mm, α is 57°-63° and P is 2.5mm-4.5mm; 19mm≤t<24mm, α is 47°-53° and P is 2.5mm-4.5mm; 24mm≤t<31mm, α is 47°-53° and P is 4.5mm-6.5mm; 31mm≤t<38mm, α is 42°-45° and P is 5.5mm-7.5mm. Step 2, Apply the bottom layer of flux (3); The thickness of the bottom flux layer is 4mm-6mm, and the width is 100mm-120mm; Step 3: Inflate the air hose (5) to make the copper gasket (4) fit tightly against the workpiece; Compressed air is filled into the air hose at a pressure of 0.1Mpa-0.22Mpa to make the gasket fit tightly against the workpiece. In order to make the bottom flux (3) fit tightly against the plate, it is necessary to use a hammer to evenly tap within 100mm on both sides of the joint on the steel plate surface. Step 4: Adjust the spacing and extension length of the welding wire (1); The spacing and extension length of the above welding wire (1) must meet the following requirements: the spacing between electrode L and electrode T1 is 35mm, the spacing between electrode T1 and electrode T2 is 120mm, the extension lengths of electrodes L, T1, and T2 are 35mm, 45mm, and 55mm respectively, and the angles between electrodes L, T1, and T2 and the vertical direction are 15°, 0°, and 5° respectively. Step 5: Use submerged arc welding to achieve efficient welding with single-sided welding and double-sided forming.

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