Welding method of S450J0 hot-rolled H-shaped steel with flange thickness of 50-80mm

Abstract

The invention discloses a welding method for S450J0 hot-rolled H-shaped steel with the flange thickness being 50-80 mm. The welding method comprises the steps that S1, a welding joint is machined to form a groove structure; s2, preheating treatment is conducted, specifically, the base metal is preheated, and the preheating temperature of the base metal is larger than or equal to 60 DEG C; s3, welding is conducted, specifically, CO2 gas shielded welding is adopted, and multi-layer and multi-pass surfacing welding is adopted; and S4, heat preservation treatment is conducted, specifically, heat preservation treatment is conducted on a welded joint after welding, and the heat preservation temperature is 168-204 DEG C. According to the welding method for the hot-rolled H-shaped steel, the welding requirement of the S450J0 hot-rolled H-shaped steel with the flange thickness being 50-80 mm can be met, a welded joint obtains the same mechanical property as a base material, and the engineering use requirement is met.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material welding, and in particular relates to a welding method for S450J0 hot-rolled H-shaped steel with a flange thickness of 50 to 80 mm. Background Art

[0002] Hot-rolled H-shaped steel has good uniformity of cross-sectional properties, stable quality, simple processing, short construction period, and easy component standardization; as an environmentally friendly steel structural material, it is widely used in the fields of transportation, construction, bridges, and offshore oil platforms. S450J0 steel is a non-alloy structural steel plate in the European standard EN10025 structural steel. The yield strength of S450J0 hot-rolled H-shaped steel reaches more than 490MPa, the tensile strength reaches more than 610MPa, and the elongation after fracture is greater than 20%.

[0003] Welding is one of the important connection methods for heavy hot-rolled H-beams, but the flange thickness of S450J0 hot-rolled H-beams is large (≤80mm), and the processing residence time is long during the welding process. There are key problems such as grain coarsening in the heat-affected zone, unbalanced microstructure transformation and hardening, which have a direct impact on the mechanical properties of the welded joints, and even cracking due to performance incompatibility, which seriously affects the progress of the project and causes economic losses, and there are major hidden dangers; although riveting can be used in bridges and buildings, it cannot achieve lightweight. In addition, the microstructure of S450J0 heavy hot-rolled H-beams is different from that of carbon steels of the same grade, and a smaller line energy is required on site to avoid the generation of cracks. Therefore, it is extremely necessary to study the welding process of S450J0 hot-rolled H-beams and apply it in actual projects.

[0004] The patent document with publication number CN106363281A discloses a welding method for Q390GJC steel for building structures, which adopts submerged arc automatic welding and CO2 gas shielded welding, with a preheating temperature of 60°C before welding, and multi-layer multi-pass welding, with an interlayer temperature of 150-200°C. The advantage is that it solves the welding problem of Q390GJC steel according to the composition range and technical conditions. When Q390GJC steel is welded using this technical solution, the welded joint obtains the same mechanical properties as the parent material, meeting the requirements of engineering use.

[0005] The patent document with publication number CN106270952A discloses a welding method for Q345GJB steel for building structures, which adopts submerged arc automatic welding and CO2 gas shielded welding; no preheating before welding, multi-layer and multi-pass welding, and the interlayer temperature is 150-200°C; the advantage is that according to the composition range and technical conditions of Q345GJB, the welding method and process problems of this steel are solved. When Q345GJB steel is welded by the above technical solution, the welded joint obtains the same mechanical properties as the parent material, meeting the requirements of engineering use.

[0006] In summary, it is necessary to conduct welding tests on S450J0 hot-rolled H-beams with flange thickness of 50 to 80 mm to determine reasonable welding methods and processes so that the welded joints can meet the requirements of engineering use. However, the existing welding methods cannot meet the welding requirements of S450J0 hot-rolled H-beams with flange thickness of 50 to 80 mm, and cannot enable the welded joints to obtain the same mechanical properties as the parent material. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a hot-rolled H-beam welding method, the purpose of which is to meet the welding requirements of S450J0 hot-rolled H-beam with a flange thickness of 50 to 80 mm, so that the welded joint obtains the same mechanical properties as the parent material.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is: a welding method of S450J0 hot-rolled H-beam with a flange thickness of 50 to 80 mm, comprising the steps of:

[0009] S1. Processing the weld joint to form a groove structure;

[0010] S2. Preheating treatment:

[0011] Preheat the base metal, the preheating temperature of the base metal is ≥60℃;

[0012] S3. Welding:

[0013] CO2 gas shielded welding, using multi-layer and multi-pass cladding welding;

[0014] S4. Insulation treatment:

[0015] After welding, the welded joints are subjected to insulation treatment at a temperature of 168 to 204°C.

[0016] In the step S3, the welding wire is subjected to a heat preservation and drying treatment before welding, and the heat preservation temperature is ≤200°C.

[0017] The welding wire is subjected to heat preservation and drying treatment for 2.5 to 3.5 hours.

[0018] In step S3, the welding joint is in the form of butt flat welding or butt horizontal welding.

[0019] In the step S3, when the welding joint is butt welding, the groove structure adopts a single-sided V-shaped groove, the groove angle is 45°, the welding current is 170-230A, the voltage is 26-34V, and the welding speed is 14-26cm / min.

[0020] In step S3, when the welding joint is butt welding, the interpass temperature of the base layer is 141-183°C, the interpass temperature of the filling layer is 168-204°C, and the interpass temperature of the cover layer is 179-194°C.

[0021] In the step S3, when the welding joint adopts butt-joint horizontal welding, the groove structure adopts a double-sided V-shaped groove, the groove angle is 60°, the welding current is 165-225A, the voltage is 25-31V, and the welding speed is 17-27cm / min.

[0022] In step S3, when the welding joint is in the form of butt-welding, the interpass temperature of the base layer is 161-189°C, the interpass temperature of the filling layer is 175-203°C, and the interpass temperature of the cover layer is 172-188°C.

[0023] The welding wire used is CHT711 flux-cored welding wire with a wire diameter of 1.2 mm.

[0024] The hot-rolled H-beam welding method of the present invention can meet the welding requirements of S450J0 hot-rolled H-beam with a flange thickness of 50 to 80 mm, so that the welded joint obtains the same mechanical properties as the parent material and meets the requirements for engineering use. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention includes the following drawings, which show:

[0026] Figure 1 is a flow chart of the hot-rolled H-beam welding method of the present invention;

[0027] Figure 2 It is a schematic diagram of the placement of the parent material for butt welding;

[0028] Figure 3 It is a schematic diagram of butt welding results;

[0029] Figure 4 It is a schematic diagram of the placement of the parent material for butt-jointed horizontal welding;

[0030] Figure 5 This is a schematic diagram of the results of butt horizontal welding. DETAILED DESCRIPTION

[0031] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention and facilitating their implementation.

[0032] like Figure 1 As shown, the present invention provides a S450J0 hot-rolled H-beam welding method with a flange thickness of 50 to 80 mm, comprising the following steps:

[0033] S1. Processing the weld joint to form a groove structure;

[0034] S2. Preheating treatment:

[0035] Preheat the base metal, the preheating temperature of the base metal is ≥60℃;

[0036] S3. Welding:

[0037] CO2 gas shielded welding, using multi-layer and multi-pass cladding welding;

[0038] S4. Insulation treatment:

[0039] After welding, the welded joints are subjected to insulation treatment at a temperature of 168 to 204°C.

[0040] Specifically, the base material is a S450J0 hot-rolled H-shaped flange, and the base material has a thickness of 50 to 80 mm. In the above step S3, the welding joint is in the form of butt flat welding or butt horizontal welding. CO2 gas shielded welding is used, and the welding wire used is CHT711 flux-cored welding wire, and the welding wire diameter is 1.2 mm.

[0041] In the above step S2, the base material is preheated before welding, and the preheating temperature is reasonably set to avoid cold crack defects at the joint.

[0042] In the above step S3, the welding wire is subjected to heat preservation and drying treatment before welding, and the heat preservation temperature is ≤200°C. The time of heat preservation and drying treatment of the welding wire is 2.5 to 3.5 hours, preferably 3.0 hours. This arrangement can reduce the probability of rusting of the welding wire surface when exposed to the air, and avoid the generation of cold cracks caused by hydrogenation of the weld during welding.

[0043] In the above step S3, multi-layer multi-pass surfacing welding is adopted, and the interlayer temperature is ≤250° C. In this way, multi-layer multi-pass welding can improve the quality of weld metal, and the latter weld has a heat treatment effect on the former weld, which is equivalent to a normalizing treatment of the former weld, and can improve the secondary structure.

[0044] In the above step S3, when the welding joint adopts butt welding, the groove structure adopts a single-sided V-shaped groove, the groove angle is 45°, the blunt edge is ≤10mm, the root gap is ≤15mm, the welding current is 170-230A, the voltage is 26-34V, the welding speed is 14-26cm / min, and the line energy is 10.3-34.1kJ / cm; the interpass temperature of the base layer is 141-183°C, the interpass temperature of the filling layer is 168-204°C, and the interpass temperature of the cover layer is 179-194°C. When welding with this process, while ensuring good welding quality, it can also prevent the welded workpiece from deformation.

[0045] In the above step S3, when the welding joint is in the form of butt horizontal welding, the groove structure adopts a double-sided V-shaped groove, the groove angle is 60°, the blunt edge is ≤10mm, the root gap is ≤15mm, the welding current is 165-225A, the voltage is 25-31V, the welding speed is 17-27cm / min, and the line energy is 9.2-24.9kJ / cm; the interpass temperature of the base layer is 161-189°C, the interpass temperature of the filling layer is 175-203°C, and the interpass temperature of the cover layer is 172-188°C.

[0046] In the above step S4, the welded joint is subjected to insulation treatment after welding, and the insulation temperature is 168-204°C, and the insulation time is ≥2h. After welding, the welded joint is subjected to insulation treatment, and the insulation temperature and time are reasonably set to avoid cold crack defects in the joint. With this setting, if the insulation temperature is too low or the insulation time is too short, it is not conducive to hydrogen release and welding cold cracks are likely to occur; if the insulation temperature is too high or the insulation time is too long, it is easy to cause coarse grains in the joint structure and reduce the mechanical properties of the welded joint. The test was carried out with the insulation temperature and time in the article, and the quality of the welded joint was good.

[0047] In Examples 1, 2, 3, and 4, the described welding process is used to successfully weld S450J0 hot-rolled H-shaped steel with a flange thickness of 50 to 80 mm without any defects, such as cracks, slag inclusions, and incomplete penetration. Therefore, the welding of the parent material can be completed using the process of the present invention.

[0048] Table 2 shows the mechanical properties of the base material. From the mechanical properties of the embodiment shown in Table 3, it can be seen that the selected welding wire and the base material meet the principle of equal strength matching, and the data of the example shown is sufficient to prove it.

[0049] In the present invention, the chemical composition of S450J0 hot-rolled H-beam is shown in Table 1, and the mechanical properties are shown in Table 2:

[0050] Table 1 Chemical composition of S450J0 hot-rolled H-beam (unit: wt%)

[0051] C Si Mn P S V N ≤0.20 ≤0.55 ≤1.60 ≤0.030 ≤0.030 ≤0.130 ≤0.025

[0052] Table 2 Mechanical properties of S450J0 hot rolled H-beam

[0053]

[0054] In the above step S2, the base material includes the following components in mass percentage:

[0055] C≤0.20%, Si≤0.55%, Mn≤1.60%, P≤0.030%, S≤0.030%, N≤0.025%, V≤0.130%, and the rest are Fe and trace residual elements.

[0056] Example 1

[0057] In the hot-rolled H-beam welding method of this embodiment, the thickness of the base material is 70 mm, the welding joint form adopts butt welding, CO2 gas shielded welding is adopted during welding, the size of the two base materials is 400 mm*100 mm*70 mm, the groove size and the specific situation of the joint are shown in Figure 2 The schematic diagram of weld bead arrangement is shown in Figure 3 shown.

[0058] In step S2 of the present embodiment, the temperature at which the base material is preheated is 80°C.

[0059] In step S3 of this embodiment, the welding current is 180-200A, the voltage is 27-32V, the welding speed is 14-25cm / min, and the line energy is 11.6-30.6kJ / cm; the interpass temperature of the base layer is 145-183°C, the interpass temperature of the filling layer is 168-204°C, and the interpass temperature of the cover layer is 179-194°C.

[0060] Comparative Example 1

[0061] In the hot-rolled H-beam welding method of this comparative example, the thickness of the base material is 70 mm, the welding joint is butt welding, CO2 gas shielded welding is used during welding, the size of the two base materials is 400 mm*100 mm*70 mm, the groove size and the specific conditions of the joint are shown in Figure 2 The schematic diagram of weld bead arrangement is shown in Figure 3 shown.

[0062] In step S2 of this comparative example, the temperature at which the base material is preheated is 80°C.

[0063] In step S3 of this comparative example, the root gap is 6 mm, the welding current is 170-200 A, the voltage is 26-30 V, the welding speed is 20-27 cm / min, and the line energy is 9.8-18.1 kJ / cm; the interpass temperature of the base layer is 155-185°C, the interpass temperature of the filling layer is 168-205°C, and the interpass temperature of the cover layer is 180-195°C.

[0064] When welding is performed using the welding process of comparative example 1, the welded workpiece has a lack of penetration defect, while when welding is performed according to the process shown in embodiment 1, the quality of the welded workpiece is good.

[0065] Example 2

[0066] In the hot-rolled H-beam welding method of this embodiment, the thickness of the base material is 50 mm, CO2 gas shielded welding is adopted during welding, and the sizes of the two base materials are 400 mm*100 mm*50 mm.

[0067] In step S2 of the present embodiment, the temperature at which the base material is preheated is 80°C.

[0068] In step S3 of this embodiment, the welding current is 175-215A, the voltage is 26-30V, the welding speed is 16-24cm / min, and the line energy is 11.4-23.9kJ / cm; the interpass temperature of the base layer is 150-183°C, the interpass temperature of the filling layer is 168-204°C, and the interpass temperature of the cover layer is 179-194°C.

[0069] Example 3

[0070] In the hot-rolled H-beam welding method of this embodiment, the thickness of the base material is 70 mm, the welding joint form adopts butt horizontal welding, CO2 gas shielded welding is adopted during welding, the size of the two base materials is 150 mm*100 mm*70 mm, the groove size and the specific situation of the joint are shown in Figure 4 The schematic diagram of weld bead arrangement is shown in Figure 5 shown.

[0071] In step S2 of the present embodiment, the temperature at which the base material is preheated is 80°C.

[0072] In step S3 of this embodiment, the welding current is 170-210A, the voltage is 26-31V, the welding speed is 20-26cm / min, and the line energy is 10.3-21.7kJ / cm; the interpass temperature of the base layer is 165-183°C, the interpass temperature of the filling layer is 168-204°C, and the interpass temperature of the cover layer is 179-194°C.

[0073] Example 4

[0074] In the hot-rolled H-beam welding method of this embodiment, the thickness of the base material is 50 mm, CO2 gas shielded welding is adopted during welding, and the sizes of the two base materials are 150 mm*100 mm*50 mm.

[0075] In step S2 of the present embodiment, the temperature at which the base material is preheated is 80°C.

[0076] In step S3 of this embodiment, the welding current is 180-215A, the voltage is 25-29V, the welding speed is 18-26cm / min, and the line energy is 10.5-20.8kJ / cm; the interpass temperature of the base layer is 170-183°C, the interpass temperature of the filling layer is 168-204°C, and the interpass temperature of the cover layer is 179-194°C.

[0077] Comparative Example 2

[0078] In the hot-rolled H-beam welding method of this comparative example, the thickness of the base material is 50 mm, CO2 gas shielded welding is adopted during welding, and the sizes of the two base materials are 150 mm*100 mm*50 mm.

[0079] In step S2 of this comparative example, the temperature at which the base material is preheated is 80°C.

[0080] In step S3 of this comparative example, the welding current is 175-210A, the voltage is 24-28V, the welding speed is 16-23cm / min, and the line energy is 11.0-21.1kJ / cm; the interpass temperature of the base layer is 160-180°C, the interpass temperature of the filling layer is 180-195°C, and the interpass temperature of the cover layer is 175-190°C.

[0081] When welding is performed using the welding process of comparative example 2, deformation and bending defects occur in the welded workpiece, while welding is performed using the process shown in example 4, and the quality of the welded workpiece is good.

[0082] According to the above joint forms and welding methods, the relevant processes used are shown in Table 3.

[0083] Table 3 Implementation cases

[0084]

[0085] The welding material involved in the present invention is CHT711 flux-cored welding wire, the diameter of the welding wire is 1.2 mm, CO2 gas shielded welding is adopted, and the polarity is reverse direct current.

[0086] The implementation effects of the present invention are as follows:

[0087] Appearance inspection: The weld surface is well formed and there are no welding defects.

[0088] Non-destructive testing of welds: Ultrasonic testing is used, and the assessment level is II, and the intrinsic quality of the welds is qualified.

[0089] Sample processing and inspection:

[0090] The tensile specimens are processed according to the provisions of GB / T2651 "Welded Joint Tensile Test Method". The bending specimens are processed according to GB / T2653 "Welded Joint Bend Test Method". The impact specimens are processed according to GB / T2650 "Welded Joint Impact Test Method".

[0091] The present invention aims at the composition range and technical conditions of S450J0 hot-rolled H-beam, and solves the welding method and process problems of the flange of hot-rolled H-beam with a flange thickness of 50 to 80 mm. Specifically, the invention includes: 1) Proposing a reasonable groove form and welding method according to the joint form and the thickness of the parent material; 2) Preheating temperature before welding and insulation temperature after welding to avoid cold crack defects at the joint; 3) Selecting appropriate welding materials according to the joint form, groove form and welding method; 4) Proposing corresponding appropriate welding process parameters. The present invention is used to weld the flange of S450J0 hot-rolled H-beam, and the welded joint obtains the same mechanical properties as the parent material, meeting the use requirements of the project.

[0092] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above-mentioned concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A welding method for S450J0 hot-rolled H-beam with flange thickness of 50 to 80 mm, characterized in that: Includes steps: S1. Processing the weld joint to form a groove structure; S2. Preheating treatment: Preheat the base metal, the preheating temperature of the base metal is ≥60℃; S3. Welding: CO2 gas shielded welding, using multi-layer and multi-pass cladding welding; S4. Insulation treatment: After welding, the welded joints are subjected to insulation treatment at a temperature of 168 to 204°C.

2. The S450J0 hot-rolled H-beam welding method with a flange thickness of 50 to 80 mm according to claim 1, characterized in that: In the step S3, the welding wire is subjected to a heat preservation and drying treatment before welding, and the heat preservation temperature is ≤ 200°C.

3. The S450J0 hot-rolled H-beam welding method with a flange thickness of 50 to 80 mm according to claim 2, characterized in that: The welding wire is subjected to heat preservation and drying treatment for 2.5 to 3.5 hours.

4. The S450J0 hot-rolled H-beam welding method with a flange thickness of 50 to 80 mm according to any one of claims 1 to 3, characterized in that: In step S3, the welding joint is in the form of butt flat welding or butt horizontal welding.

5. The S450J0 hot-rolled H-beam welding method with a flange thickness of 50 to 80 mm according to claim 4, characterized in that: In the step S3, when the welding joint is butt welding, the groove structure adopts a single-sided V-shaped groove, the groove angle is 45°, the welding current is 170-230A, the voltage is 26-34V, and the welding speed is 14-26cm / min.

6. The S450J0 hot-rolled H-beam welding method with a flange thickness of 50 to 80 mm according to claim 4, characterized in that: In step S3, when the welding joint is butt welding, the interpass temperature of the base layer is 141-183°C, the interpass temperature of the filling layer is 168-204°C, and the interpass temperature of the cover layer is 179-194°C.

7. The S450J0 hot-rolled H-beam welding method with a flange thickness of 50 to 80 mm according to claim 4, characterized in that: In the step S3, when the welding joint adopts butt-joint horizontal welding, the groove structure adopts a double-sided V-shaped groove, the groove angle is 60°, the welding current is 165-225A, the voltage is 25-31V, and the welding speed is 17-27cm / min.

8. The S450J0 hot-rolled H-beam welding method with a flange thickness of 50 to 80 mm according to claim 7, characterized in that: In step S3, when the welding joint is in the form of butt-welding, the interpass temperature of the base layer is 161-189°C, the interpass temperature of the filling layer is 175-203°C, and the interpass temperature of the cover layer is 172-188°C.

9. The S450J0 hot-rolled H-beam welding method with a flange thickness of 50 to 80 mm according to any one of claims 1 to 8, characterized in that: The welding wire used is CHT711 flux-cored welding wire with a wire diameter of 1.2 mm.

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