Welding method of Q345qD-IMEC corrosion-resisting steel for bridge

Abstract

The invention relates to a welding method of Q345qD-IMEC corrosion-resisting steel for bridges, which comprises the following steps: selecting a welding material: adopting a combination of a welding wire and a welding flux for submerged-arc welding, adopting at least one of the following welding wires: a flux-cored welding wire and a solid welding wire for CO2 gas shielded welding, machining a groove: machining the groove according to a welding joint form, according to the welding process, the welding parameters of submerged arc welding are that the current is 620 + / -30 A, the voltage is 28 + / -2 V, and the welding speed is 34-36 cm / min; the welding parameters of CO2 gas shielded welding are as follows: the current is 140-270 A, the voltage is 26-30 V, the welding speed is 10-25 cm / min, and the gas flow is 16-22 L / min; and then post-welding detection is carried out.

Description

Technical Field

[0001] The invention relates to the technical field of steel material welding, in particular to a welding method for Q345qD-IMEC corrosion-resistant steel for bridges. Background Art

[0002] Traditional bridge steel is susceptible to rust in corrosive environments, requiring frequent maintenance. While Q345qD-IMEC corrosion-resistant steel has significantly improved its corrosion resistance through nano-modification technology, its welding process lacks mature solutions. Existing welding methods suffer from low efficiency and insufficient joint toughness, making them inadequate for bridge construction. This invention addresses these issues by optimizing welding material matching, groove configuration, and welding parameters. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to propose a welding method for Q345qD-IMEC corrosion-resistant steel for bridges with good welding quality and high construction efficiency in response to the deficiencies in the above-mentioned prior art.

[0004] The present invention solves the above-mentioned problem by adopting the following preparation method and technical solution:

[0005] A welding method for Q345qD-IMEC corrosion-resistant steel for bridges, characterized by comprising the following steps:

[0006] (1) Welding material selection:

[0007] Submerged arc welding uses a combination of welding wire and flux, the chemical composition of which satisfies C≤0.12%, Si≤0.07%, and Mn 1.50-1.90%;

[0008] CO2 gas shielded welding uses at least one of the following welding wires:

[0009] Flux-cored welding wire, the chemical composition of which satisfies C≤0.18%, Si≤0.90%, Mn≤2.0%;

[0010] Solid welding wire, its chemical composition meets C: 0.06-0.15%, Si: 0.80-1.15%, Mn: 1.40-1.85%;

[0011] (2) Groove processing: Process the groove according to the form of the weld joint. The groove form includes Y-type, V-type or single-sided V-type, the groove angle is 45°-50°, and the blunt edge is 2-4mm;

[0012] (3) Welding process:

[0013] The welding parameters for submerged arc welding were current 620±30A, voltage 28±2V, and welding speed 34-36cm / min;

[0014] The welding parameters of CO2 gas shielded welding are current 140-270A, voltage 26-30V, welding speed 10-25cm / min, and gas flow rate 16-22L / min;

[0015] (4) Post-weld inspection: The welded joint shall be free of cracks, lack of fusion, or slag inclusion defects, and the tensile strength shall be ≥490 MPa and the impact energy at -20°C shall be ≥27 J.

[0016] According to the above technical solution, environmental control is also included: environmental humidity during welding is ≤80%, wind speed is ≤2m / s, and CO2 gas purity is ≥99.5%.

[0017] According to the above technical scheme, when the welding joint is a flat butt joint, the two welding surfaces are processed into a Y-shaped groove with a groove angle of 50° and a blunt edge of 4mm. Non-backed flat butt submerged arc welding is adopted. First, a flux-cored wire or solid wire is used for the base welding, and then submerged arc welding wire and flux are used for filling and covering.

[0018] According to the above technical solution, when the welding joint is parallel or vertically butted, a V-shaped groove is adopted, and ceramic liner gas shielded welding is adopted. A flux-cored wire or solid wire is selected for base welding before filling and covering.

[0019] According to the above technical solution, when the welding joint is a vertical T-shaped fillet joint, a horizontal T-shaped fillet joint or an upward T-shaped fillet joint, single-sided V-shaped groove welding is adopted, gas shielded welding with full penetration and root cleaning on the reverse side is selected, and flux-cored wire or solid wire is used for base welding before filling and covering.

[0020] According to the above technical solution, when the welding joint is a vertical T-shaped fillet joint, a horizontal T-shaped fillet joint or an upward T-shaped fillet joint, a single-sided V-shaped groove is used, partial penetration welding is selected, and flux-cored wire or solid wire is used to perform bottom welding first and then reverse welding.

[0021] According to the above technical solution, when the ambient temperature is lower than 5°C or the plate thickness is ≥30mm, the preheating temperature is 60-120°C, and the preheating range is more than 100mm on both sides of the weld.

[0022] According to the above technical solution, the welding method is suitable for butt joints, T-shaped fillet joints, full penetration welding and partial penetration welding of bridge steel structures.

[0023] According to the above technical solution, the chemical composition of the weld metal of the welding material matches that of the Q345qD-IMEC corrosion-resistant steel base material, and the weld structure is mainly fine-grained ferrite.

[0024] According to the above technical solution, the welding method is also applicable to the welding of other IMEC corrosion-resistant steels.

[0025] The beneficial effects of the present invention are:

[0026] 1. This invention ensures metallurgical compatibility between the weld metal and the base metal by matching the chemical composition of the welding materials (for example, C ≤ 0.12% and Mn 1.50-1.90% in submerged arc welding wire, similar to that of the base metal) and designing a low-heat-input process. The welded joints produced using this method not only exhibit excellent mechanical properties and corrosion resistance, but also achieve high welding efficiency, resolving technical challenges in bridge welding processes and manufacturing.

[0027] 2. The present invention optimizes welding efficiency and joint performance by combining the high efficiency of submerged arc welding with the flexibility of gas shielded welding.

[0028] 3. This method supports multiple positions such as flat welding, vertical welding, horizontal welding, overhead welding, etc., and adapts to different joint requirements through groove forms (Y-type, V-type, single-sided V-type), covering multiple scenarios and material expansion, and has strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 Schematic diagram of butt submerged arc welding provided in this embodiment 1.

[0031] Figure 2 This is a schematic diagram of butt submerged arc welding cladding provided in Example 2.

[0032] Figure 3 This is a schematic diagram of the vertical butt welding provided in Example 2.

[0033] Figure 4 This is a schematic diagram of the vertical butt welding cladding provided in Example 2.

[0034] Figure 5 This embodiment 3 provides a schematic diagram of flat butt welding.

[0035] Figure 6 This is a schematic diagram of the flat butt welding cladding provided in Example 3.

[0036] Figure 7 This is a schematic diagram of the vertical penetration welding provided in this embodiment 4.

[0037] Figure 8 This is a schematic diagram of the vertical penetration welding cladding provided in this embodiment 4.

[0038] Figure 9 This is the horizontal penetration welding provided in Example 5.

[0039] Figure 10 This is a simplified diagram of horizontal penetration welding provided in Example 5.

[0040] Figure 11 This is a schematic diagram of the overhead penetration welding provided in Example 6.

[0041] Figure 12 This is a schematic diagram of the overhead penetration welding cladding provided in Example 6.

[0042] Figure 13 Schematic diagram of the standing groove welding provided in this embodiment 7.

[0043] Figure 14 A schematic diagram of the standing groove welding cladding provided in Example 7.

[0044] Figure 15 Schematic diagram of horizontal groove welding provided in this embodiment 8.

[0045] Figure 16 A schematic diagram of the horizontal groove welding cladding provided in Example 8.

[0046] Figure 17 Schematic diagram of the overhead groove welding provided in this embodiment 9.

[0047] Figure 18 A schematic diagram of the upward groove welding cladding provided in Example 9.

[0048] Figure 19 Schematic diagram of the overhead groove welding provided in this embodiment 10.

[0049] Figure 20 A schematic diagram of the upward groove welding cladding provided in Example 10.

[0050] Figure 21 Schematic diagram of the vertical groove welding provided in this embodiment 11.

[0051] Figure 22 A schematic diagram of the vertical groove welding cladding provided for this embodiment 11.

[0052] Figure 23 This is a schematic diagram of the flat fillet welding provided in Example 12.

[0053] Figure 24 This is a simplified diagram of the flat fillet welding cladding provided in Example 12. DETAILED DESCRIPTION

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0055] This embodiment provides a welding method for Q345qD-IMEC corrosion-resistant steel for bridges. The Q345qD-IMEC corrosion-resistant steel plate has a yield strength Rel ≥ 345 MPa, a tensile strength Rm ≥ 490 MPa, an elongation A ≥ 20%, and an impact energy KV2 ≥ 120 J at -20°C. The welding method includes the following steps:

[0056] (1) Welding material selection:

[0057] Submerged arc welding uses SU34 (Φ4.0mm) + flux FB (SJ-101q). The chemical composition (weight percentage) of this combined welding wire meets C≦0.12, Si≦0.07, Mn: 1.50-1.90, P≦0.03, S≦0.03, Ni≦0.30, Cr≦0.20, Cu≦0.35; its performance meets the requirements of "Solid welding wire, flux-cored welding wire and welding wire-flux combination of non-alloy steel and fine-grained steel for submerged arc welding" (GB / T 5293-2018).

[0058] CO2 gas shielded welding uses at least one of the following welding wires:

[0059] Flux-cored welding wire T492T1-1 C1A (Φ1.2), its chemical composition (weight percentage) meets C≦0.18, Si≦0.90, Mn≦2.0, P≦0.03, S≦0.03, Ni≦0.50, Cr≦0.2, Mo≦0.30, V≦0.08; the performance of T492T1-1 C1A flux-cored welding wire meets the requirements of "Flux-cored Welding Wire for Non-alloy Steel and Fine Grain Steel" (GB / T 10045-2018).

[0060] Solid welding wire G49A3C1S6 (Φ1.2), its chemical composition (weight percentage) meets C: 0.06-0.15, Si: 0.80-1.15, Mn: 1.40-1.85, P≦0.025, S≦0.025, Ni≦0.15, Cr≦0.15, Cu≦0.50, Mo≦0.15, V≦0.03; the performance of G49A3C1S6 solid welding wire meets the requirements of "Solid Welding Wire for Non-alloy Steel and Fine Grain Steel for Metallic Electrode Gas Arc Welding" (GB / T 8110-2020).

[0061] T492T1-1C1A tensile strength Rm490-670MPa, yield strength Rel≥390MPa, elongation A≥18%, impact energy KV2≥27J at -20℃; G49A3C1S6 tensile strength Rm490-670MPa, yield strength Rel≥390MPa, elongation A≥22%, impact energy KV2≥27J at -30℃; SU34+FB(SJ101q) tensile strength Rm490-670MPa, yield strength Rel≥390MPa, elongation A≥18%, impact energy KV2≥47J at -40℃.

[0062] (2) Groove processing: Process the groove according to the form of the weld joint. The groove form includes Y-type, V-type or single-sided V-type, the groove angle is 45°-50°, and the blunt edge is 2-4mm;

[0063] (3) Before formal welding, the test plate with an environment below 5℃ or a plate thickness ≥30mm should be preheated to 60-120℃. Use a drying gun to heat evenly. The preheating range is on both sides of the weld, with a width of more than 100mm.

[0064] Humidity should not exceed 80% during welding. Major components should be welded within 24 hours of assembly. When wind speeds exceed 2 m / s, enclosures and shielding measures should be implemented, and open-air welding is prohibited. Gas shielded welding uses a CO2 shielding gas with a concentration of 99.5% or higher. The submerged arc welding flux baking temperature is 350°C, the storage temperature is 100-230°C, and the holding time is 2 hours.

[0065] (4) Welding process:

[0066] The welding parameters for submerged arc welding were current 620±30A, voltage 28±2V, and welding speed 34-36cm / min;

[0067] The welding parameters of CO2 gas shielded welding are current 140-270A, voltage 26-30V, welding speed 10-25cm / min, and gas flow rate 16-22L / min;

[0068] Post-weld inspection: The welded joints are free of defects such as cracks, lack of fusion, slag inclusions, weld bumps, etc., and the mechanical properties of the welded joints meet the standard requirements of various material parameters.

[0069] The following is a specific implementation plan for the welding process: Specific embodiment 1:

[0071] Butt submerged arc welding without backing:

[0072] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*200*600, according to Figure 1The groove processing is Y-shaped groove, with a groove angle of 50° and a blunt edge of 4mm. The name of the plate, the front and back sides are marked. The two test plates are assembled and positioned. The assembly accuracy gap is 0-1mm and the misalignment does not exceed 1mm. After cleaning the surface, weld it according to Figure 2 The welding sequence shown is to perform backing welding first, using G49A3C1S6 welding wire, welding current 200±10A, voltage 28±2V, welding speed 17-19cm / min, wire energy 13-18KJ / cm, gas flow 16-18L / min, and then perform filling and covering, using submerged arc welding wire and flux SU34+FB (SJ101q), welding current 620±30A, voltage 28±2V, welding speed 34-36cm / min, wire energy 25-35KJ / cm. Specific embodiment 2:

[0074] Ceramic liner gas shielded welding vertical butt joint:

[0075] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*200*600, according to Figure 3 The groove processing is V-shaped groove with a groove angle of 45°, and the name of the plate, front and back are marked. The two test plates are assembled and positioned, and the assembly accuracy gap is 0-1mm, and the misalignment does not exceed 1mm. After cleaning the surface, weld it according to Figure 4 The welding sequence shown is to first perform the base welding, using T492T1-1C1A welding wire, welding current 140±10A, voltage 26±2V, welding speed 12-14cm / min, gas flow 18-20L / min, and line energy 13-18KJ / cm, and then perform the filling and capping, welding current 160±10A, voltage 28±2V, welding speed 10-12cm / min, gas flow 18-20L / min, and line energy 13-18KJ / cm. Specific Example 3:

[0076] Ceramic liner gas shielded welding flat butt:

[0077] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*200*600, according to Figure 5 The groove processing is V-shaped groove with a groove angle of 45°, and the name of the plate, front and back are marked. The two test plates are assembled and positioned, and the assembly accuracy gap is 0-1mm, and the misalignment does not exceed 1mm. After cleaning the surface, weld it according to Figure 6The welding sequence shown is to perform backing welding first, using G49A3C1S6 welding wire, welding current 200±10A, voltage 26±2V, welding speed 17-19cm / min, gas flow 16-18L / min, and linear energy 13-18KJ / cm, and then perform filling and covering, welding current 260±10A, voltage 30±2V, welding speed 19-21cm / min, gas flow 16-18L / min, and linear energy 15-22KJ / cm. Specific embodiment 4:

[0079] Standing position penetration and reverse side root cleaning gas shielded welding:

[0080] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*150*400, and Figure 7 As shown in the figure, Q345qD is grooved into a single-sided V-shaped groove with a groove angle of 45° and a blunt edge of 2mm. The name of the plate, the front and back sides are marked. The two test plates are assembled and positioned with an assembly accuracy gap of 0 to 1mm. The surfaces are cleaned and then welded. Figure 8 The welding sequence shown is to first perform the bottom welding, using T492T1-1C1A welding wire, welding current 140±10A, voltage 26±2V, welding speed 13-15cm / min, gas flow 18-20L / min, and line energy 13-18KJ / cm, and then perform the back cleaning welding, welding current 160±10A, voltage 28±2V, welding speed 11-13cm / min, gas flow 18-20L / min, and line energy 15-22KJ / cm. Specific Example 5:

[0081] Horizontal penetration and reverse side root cleaning gas shielded welding:

[0082] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*150*400, and Figure 9 As shown in the figure, Q345qD is grooved into a single-sided V-shaped groove with a groove angle of 45° and a blunt edge of 2mm. The name of the plate, the front and back sides are marked. The two test plates are assembled and positioned with an assembly accuracy gap of 0 to 1mm. The surfaces are cleaned and then welded. Figure 10 The welding sequence shown is to first perform the base welding, using G49A3C1S6 welding wire, welding current 200±10A, voltage 26±2V, welding speed 17-19cm / min, gas flow 16-18L / min, and line energy 13-18KJ / cm, and then perform the back cleaning welding, welding current 260±10A, voltage 30±2V, welding speed 19-21cm / min, gas flow 16-18L / min, and line energy 15-22KJ / cm. Specific Example 6:

[0083] Upright penetration and reverse side root cleaning gas shielded welding:

[0084] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*150*400, and Figure 11 As shown in the figure, Q345qD is grooved into a single-sided V-shaped groove with a groove angle of 45° and a blunt edge of 2mm. The name of the plate, the front and back sides are marked. The two test plates are assembled and positioned with an assembly accuracy gap of 0 to 1mm. The surfaces are cleaned and then welded. Figure 12 The weld sequence shown is to first perform the backing weld, using T492T1-1C1A welding wire, welding current 150±10A, voltage 26±2V, welding speed 12-14cm / min, gas flow 20-22L / min, and line energy 13-18KJ / cm, and then perform the back cleaning weld, welding current 170±10A, voltage 28±2V, welding speed 12-14cm / min, gas flow 20-22L / min, and line energy 15-22KJ / cm. Specific Example 7:

[0085] Standing part fusion and ventilation welding:

[0086] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*150*400, and Figure 13 As shown in the figure, Q345qD is grooved into a single-sided V-shaped groove with a groove angle of 45° and a blunt edge of 2mm. The name of the plate, the front and back sides are marked. The two test plates are assembled and positioned with an assembly accuracy gap of 0 to 1mm. The surfaces are cleaned and then welded. Figure 14 The welding sequence shown is to perform the base welding first, using T492T1-1C1A welding wire, welding current 140±10A, voltage 26±2V, welding speed 11-13cm / min, gas flow 18-20L / min, and linear energy 13-18KJ / cm, and then weld on the reverse side, welding current 160±10A, voltage 28±2V, welding speed 12-14cm / min, gas flow 18-20L / min, and linear energy 15-22KJ / cm. Specific embodiment 8:

[0088] Partially melted and breathable soldering:

[0089] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*150*400, and Figure 15 As shown in the figure, Q345qD is grooved into a single-sided V-shaped groove with a groove angle of 45° and a blunt edge of 2mm. The name of the plate, the front and back sides are marked. The two test plates are assembled and positioned with an assembly accuracy gap of 0 to 1mm. The surfaces are cleaned and then welded. Figure 16The welding sequence shown is to perform the base welding first, using G49A3C1S6 welding wire, welding current 200±10A, voltage 26±2V, welding speed 17-19cm / min, gas flow 16-18L / min, and linear energy 13-18KJ / cm, and then weld on the reverse side, welding current 260±10A, voltage 30±2V, welding speed 19-21cm / min, gas flow 16-18L / min, and linear energy 15-22KJ / cm. Specific embodiment 9:

[0091] Upward partial melting and ventilation welding:

[0092] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*150*400, and Figure 17 As shown in the figure, Q345qD is grooved into a single-sided V-shaped groove with a groove angle of 45° and a blunt edge of 2mm. The name of the plate, the front and back sides are marked. The two test plates are assembled and positioned with an assembly accuracy gap of 0 to 1mm. The surfaces are cleaned and then welded. Figure 18 The welding sequence shown is to perform the base welding first, using T492T1-1C1A welding wire, welding current 150±10A, voltage 26±2V, welding speed 12-14cm / min, gas flow 20-22L / min, and linear energy 13-18KJ / cm, and then weld on the reverse side, welding current 170±10A, voltage 28±2V, welding speed 12-14cm / min, gas flow 20-22L / min, and linear energy 15-22KJ / cm. Specific embodiment 10:

[0094] Gas shielded welding of T-type fillet weld in the upward position:

[0095] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*150*400, and Figure 19 Assemble and position the two test plates as shown in the figure. The assembly accuracy gap is 0 to 1 mm. Clean the surface and weld it. Figure 20 The welding sequence shown is to perform the base welding first, using T492T1-1C1A welding wire, welding current 150±10A, voltage 26±2V, welding speed 12-14cm / min, gas flow 20-22L / min, and linear energy 13-18KJ / cm, and then weld on the reverse side, welding current 170±10A, voltage 28±2V, welding speed 12-14cm / min, gas flow 20-22L / min, and linear energy 15-22KJ / cm. Specific embodiment 11:

[0097] Standing T-type fillet weld gas shielded welding:

[0098] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*150*400, and Figure 21 Assemble and position the two test plates as shown in the figure. The assembly accuracy gap is 0 to 1 mm. Clean the surface and weld it. Figure 22 The welding sequence shown is to perform the base welding first, using T492T1-1 C1A welding wire, welding current 140±10A, voltage 26±2V, welding speed 11-13cm / min, gas flow 18-20L / min, and linear energy 13-18KJ / cm, and then weld on the reverse side, welding current 160±10A, voltage 28±2V, welding speed 12-14cm / min, gas flow 18-20L / min, and linear energy 15-22KJ / cm. Specific embodiment 12:

[0100] Horizontal T-type fillet weld gas shielded welding:

[0101] Select 1 piece of Q345qD-IMEC corrosion resistant steel plate of 16*150*400, and Figure 23 Assemble and position the two test plates as shown in the figure. The assembly accuracy gap is 0 to 1 mm. Clean the surface and weld it. Figure 24 The welding sequence shown is to perform the base welding first, using G49A3C1 S6 welding wire, welding current 200±10A, voltage 28±2V, welding speed 18-20cm / min, gas flow 16-18L / min, and linear energy 13-18KJ / cm, and then weld on the reverse side, welding current 290±10A, voltage 30±2V, welding speed 23-25cm / min, gas flow 16-18L / min, and linear energy 15-22KJ / cm.

[0102] The above describes the groove configuration, welding method, and welding parameters used in this invention for various joint configurations of Q345qD-IMEC corrosion-resistant steel for bridges. This approach balances low-temperature impact toughness and welding efficiency. For example, for plate butt welding, submerged arc welding (SAW) is used to maximize deposition efficiency. Furthermore, to ensure weld quality, gas shielded arc welding (GMAW) heat input is controlled between 13 and 25 kJ / cm, with back-strip root cleaning implemented. For T-joint fillet welds, penetration is not required, and low-temperature toughness is not a concern. Therefore, a higher heat input and the convenience and flexibility of flux-cored GMAW are employed.

[0103] The present invention is directed to Q345qD-IMEC corrosion-resistant steel for bridges. When selecting welding materials, the primary consideration is to ensure that the strength of the weld metal and the -20°C Charpy impact energy match those of the base material as closely as possible. SU34 submerged arc welding wire with a fluorine-alkali type SJ101q flux, as well as T492T1-1 C1A flux-cored welding wire and G49A3C1 S6 solid welding wire with excellent all-position welding process are selected as welding materials. This ensures that the chemical composition of the weld metal is similar to that of the base material, the weld microstructure is mainly composed of fine ferrite, and the weld has both strength and toughness. Therefore, the present invention is an ideal welding material for the Q345qD-IMEC corrosion-resistant steel for bridges.

[0104] During implementation, the present invention achieves both excellent mechanical properties and high welding efficiency, demonstrating its practicality. Therefore, the present invention plays a significant role in promoting the upgrading of bridge steel and the development of bridge construction technology. In addition to its application in bridge construction, the present invention can also be used for welding other IMEC corrosion-resistant steels, demonstrating its broad applicability.

[0105] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

Claims

1. A welding method for Q345qD-IMEC corrosion-resistant steel for bridges, characterized in that: The following steps are involved: (1) Welding material selection: Submerged arc welding uses a combination of welding wire and flux, the chemical composition of which satisfies C≤0.12%, Si≤0.07%, and Mn1.50-1.90%; CO2 gas shielded welding uses at least one of the following welding wires: Flux-cored welding wire, the chemical composition of which satisfies C≤0.18%, Si≤0.90%, Mn≤2.0%; Solid welding wire, its chemical composition meets C: 0.06-0.15%, Si: 0.80-1.15%, Mn: 1.40-1.85%; (2) Groove processing: Process the groove according to the form of the weld joint. The groove form includes Y-type, V-type or single-sided V-type, the groove angle is 45°-50°, and the blunt edge is 2-4mm; (3) Welding process: The welding parameters for submerged arc welding were current 620±30A, voltage 28±2V, and welding speed 34-36cm / min; The welding parameters of CO2 gas shielded welding are current 140-270A, voltage 26-30V, welding speed 10-25cm / min, and gas flow rate 16-22L / min; (4) Post-weld inspection: The weld joint is free of cracks, lack of fusion, and slag inclusion defects.

2. The welding method according to claim 1, wherein: It also includes environmental control: ambient humidity during welding ≤ 80%, wind speed ≤ 2m / s, CO2 gas purity ≥ 99.5%.

3. The welding method according to claim 1 or 2, characterized in that: When the welding joint is a flat butt joint, the two welding surfaces are processed into a Y-shaped groove, and a non-backed flat butt submerged arc welding is used. First, a flux-cored wire or solid wire is used for the base weld, and then a submerged arc wire and flux are used to fill and cover the surface.

4. The welding method according to claim 1 or 2, characterized in that: When the welding joint is parallel or vertical, a V-shaped groove is used, and ceramic liner gas shielded welding is adopted. Flux-cored wire or solid wire is selected for base welding before filling and covering.

5. The welding method according to claim 1 or 2, characterized in that: When the welding joint is a vertical T-type fillet joint, a horizontal T-type fillet joint or an upward T-type fillet joint, single-sided V-shaped groove welding is adopted, and gas shielded welding with reverse root cleaning is selected. A flux-cored wire or solid wire is used for base welding before filling and covering.

6. The welding method according to claim 1 or 2, characterized in that: When the welding joint is a vertical T-type fillet joint, a horizontal T-type fillet joint or an upward T-type fillet joint, a single-sided V-shaped groove is used, partial penetration welding is selected, and flux-cored wire or solid wire is used for base welding before reverse welding.

7. The welding method according to claim 2, wherein: When the ambient temperature is lower than 5℃ or the plate thickness is ≥30mm, the preheating temperature is 60-120℃, and the preheating range is more than 100mm on both sides of the weld.

8. The welding method according to claim 1 or 2, characterized in that: The welding method is applicable to butt joints, T-angle joints, full penetration welding and partial penetration welding of bridge steel structures.

9. The welding method according to claim 1, wherein: The chemical composition of the weld metal of the welding material matches that of the Q345qD-IMEC corrosion-resistant steel base material, and the weld structure is mainly fine-grained ferrite.

10. The welding method according to claim 1, wherein: The welding method is also applicable to welding other IMEC corrosion-resistant steels.

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