Angle joint full penetration welding method for Q355ME hot-rolled H-shaped steel with flange thickness of 30-50 mm

Abstract

The invention discloses a Q355ME hot-rolled H-shaped steel corner joint full penetration welding method with the flange thickness being 30-50 mm. The Q355ME hot-rolled H-shaped steel corner joint full penetration welding method comprises the following steps that (1) a reasonable groove form and a reasonable welding form are provided according to the welding joint form and the base metal thickness; (2) the preheating temperature before welding and the heat preservation temperature after welding are determined so as to avoid the cold crack defect on the joint part; (3) proper welding materials are selected according to the joint form, the groove form and the welding form; and (4) corresponding appropriate welding process parameters are provided, and welding operation is carried out. The corner joint full penetration welding method for the Q355ME hot-rolled H-shaped steel with the flange thickness being 30-50 mm is reasonable in design, a welded joint can obtain the same mechanical property as a base material, and the engineering use requirement is met; the surface of a weld joint is well formed without welding defects; an ultrasonic mode is adopted for detection, the evaluation grade is grade II, and the inherent quality of the welding seam is qualified.

Description

Technical Field

[0001] The invention relates to the technical field of hot-rolled H-shaped steel welding, in particular to a full penetration welding method for a Q355ME hot-rolled H-shaped steel fillet joint with a flange thickness of 30-50 mm. Background Art

[0002] Hot-rolled H-beam has good cross-sectional performance uniformity, stable quality, simple processing, short construction period, and easy component standardization; as an environmentally friendly steel structure material, it is widely used in the fields of transportation, construction, bridges, and offshore oil platforms. The yield strength of Q355ME hot-rolled H-beam reaches more than 355MPa, the tensile strength reaches 470-630MPa, and the elongation after fracture is greater than 22%, and it is widely used.

[0003] Welding is one of the important connection methods for heavy hot-rolled H-beams, but the flange thickness of Q355ME hot-rolled H-beams is large (30-50mm), 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. The performance is not good or even cracking, which seriously affects the progress of the project and causes economic losses. There are major hidden dangers; although riveting can be used in bridges and buildings, it cannot achieve lightweighting. Therefore, it is extremely necessary to study the welding process of Q355ME hot-rolled H-beams and apply it in actual projects.

[0004] In summary, it is necessary to conduct fillet welding tests on Q355ME hot-rolled H-beam to determine reasonable welding methods and processes so that the welded joints can meet the requirements of engineering use.

[0005] In the prior art, for example, the patent CN106270952A discloses a welding method for Q345GJB steel for building structures. The welding joint forms include butt flat welding, butt horizontal welding, corner butt flat welding, T-type corner horizontal welding, and T-type corner ship-shaped non-melting flat welding. The welding method includes submerged arc automatic welding and CO2 gas shielded welding. No preheating is performed before welding. Multi-layer and multi-pass welding is used, and the interlayer temperature is 150-200°C. It is not applicable to the welding of Q355ME hot-rolled H-shaped steel. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a full penetration welding method for Q355ME hot-rolled H-shaped steel corner joints with a flange thickness of 30-50 mm, which enables the welded joint to obtain the same mechanical properties as the parent material and meet the requirements of engineering use.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm comprises the following steps:

[0009] 1) According to the welding joint form and the thickness of the parent material, propose reasonable groove form and welding form;

[0010] 2) Determine the preheating temperature before welding and the insulation temperature after welding to avoid cold crack defects in the joint;

[0011] 3) Select appropriate welding materials according to the joint form, groove form and welding form;

[0012] 4) Propose appropriate welding process parameters and perform welding operations.

[0013] in,

[0014] The welding joint is in the form of a T-shaped corner joint or an L-shaped corner joint.

[0015] Before welding, the welding wire is kept warm and dried in a drying oven for 2-4 hours, and the insulation temperature is ≤200°C.

[0016] The base material is preheated before welding, and the preheating temperature is ≥ 60°C.

[0017] The welding operation adopts multi-layer and multi-pass surfacing welding, and the interlayer temperature is ≤250°C.

[0018] After welding, the welded joint is subjected to insulation treatment, the insulation temperature is 170-210° C., and the insulation time is ≥2h.

[0019] The welding adopts a double-sided V-shaped groove with a groove angle of 50-70°. The welding is first performed as a base welding, then a filling welding, and finally a cover welding.

[0020] The base welding adopts CO2 gas shielded welding, the welding wire is CHT711 flux-cored welding wire, the welding wire diameter is 1.1-1.3mm, the welding current is 190-230A, the voltage is 27-31V, the welding speed is 15-22cm / min, and the line energy is 14.0-28.5kJ / cm.

[0021] The filling welding adopts a submerged arc welding method, the shielding gas is 80% Ar+20% CO2, the welding wire is ER50-6 flux-cored welding wire, the welding wire diameter is 4-6mm, the welding current is 600-800A, the welding voltage is 29-35V, the welding speed is 45-65cm / min, and the line energy is 16.1-37.3kJ / cm.

[0022] The cap welding adopts submerged arc welding method, the protective gas is 80% Ar+20% CO2, the welding wire is ER50-6 flux-cored welding wire, the welding wire diameter is 4-6mm, the welding current is 650-780A, the welding voltage is 35-38V, the welding speed is 45-65cm / min, and the line energy is 21.0-39.5kJ / cm.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joints with a flange thickness of 30-50mm is reasonably designed, which can enable the welded joint to obtain the same mechanical properties as the parent material and meet the requirements of engineering use; the weld surface is well formed and free of welding defects; ultrasonic testing is used, and the assessment grade is II, and the intrinsic quality of the weld is qualified. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following is a brief description of the contents and symbols in the drawings of this specification:

[0026] Figure 1 and Figure 3 It is a schematic diagram of T-type full penetration welding of the present invention.

[0027] Figure 2 and Figure 4 It is a schematic diagram of L-type full penetration welding of the present invention. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention will be further explained in detail below through the description of embodiments with reference to the accompanying drawings.

[0029] like Figures 1 to 4 As shown, the full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm comprises the following steps:

[0030] 1) According to the welding joint form and the thickness of the parent material, propose reasonable groove form and welding form;

[0031] 2) Determine the preheating temperature before welding and the insulation temperature after welding to avoid cold crack defects in the joint;

[0032] 3) Select appropriate welding materials according to the joint form, groove form and welding form;

[0033] 4) Propose appropriate welding process parameters and perform welding operations.

[0034] The specific welding method is preferably used. At a room temperature of 10 to 30°C, the flange parent material of Q355ME with a flange thickness of 30 to 50 mm is welded, and the welding joint forms are T-type fillet joint and L-type fillet joint; the welding wire is kept warm and dried in a drying oven for 3 hours before welding, and the insulation temperature is ≤200°C; the parent material is preheated before welding, and the preheating temperature is ≥60°C; multi-layer and multi-pass surfacing welding is adopted, and the interlayer temperature is ≤250°C; after welding, the weld joint is insulated, and the insulation temperature is 170 to 210°C, and the insulation time is ≥2h.

[0035] In the full penetration welding process of the flange parent material of Q355ME with a thickness of 30 to 50 mm, a double-sided V-shaped groove with a groove angle of 60° is used. The welding is first performed as a base welding, then a filling welding, and finally a cover welding.

[0036] Among them: the base welding adopts CO2 gas shielded welding, the welding wire is CHT711 flux-cored welding wire, the welding wire diameter is 1.2mm, the welding current is 190~230A, the voltage is 27~31V, the welding speed is 15~22cm / min, and the line energy is 14.0~28.5kJ / cm;

[0037] The filling welding adopts submerged arc welding method, the shielding gas is 80% Ar + 20% CO2, the welding wire is ER50-6 flux-cored welding wire, the welding wire diameter is 5mm, the welding current is 600-800A, the welding voltage is 29-35V, the welding speed is 45-65cm / min, and the line energy is 16.1-37.3kJ / cm;

[0038] The cover welding adopts submerged arc welding method, the shielding gas is 80% Ar + 20% CO2, the welding wire is ER50-6 flux-cored wire, the welding wire diameter is 5mm, the welding current is 650~780A, the welding voltage is 35~38V, the welding speed is 45~65cm / min, and the line energy is 21.0~39.5kJ / cm.

[0039] The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm is reasonably designed, which can enable the welded joint to obtain the same mechanical properties as the parent material and meet the requirements of engineering use; the weld surface is well formed and free of welding defects; ultrasonic detection is used, and the evaluation grade is II, and the intrinsic quality of the weld is qualified.

[0040] The chemical composition of Q355ME hot-rolled H-beam is shown in Table 1, and the mechanical properties are shown in Table 2.

[0041] Table 1 Chemical composition of Q355ME hot-rolled H-beam (unit: wt%)

[0042]

[0043] Table 2 Mechanical properties of Q355ME hot rolled H-beam

[0044]

[0045] Implementation Case 1:

[0046] Q355ME flange thickness 30mm T-type full penetration welding, using CO2 gas shielded welding and submerged arc welding method, the two base materials are 400*100*50mm in size, groove size and joint details see Figure 1 The schematic diagram of weld bead arrangement is shown in Figure 3 shown.

[0047] Implementation Case 2:

[0048] Q355ME flange thickness 30mm L-type full penetration welding, using CO2 gas shielded welding and submerged arc welding method, the two base materials are 400*100*50mm in size, groove size and joint details see Figure 2 The schematic diagram of weld bead arrangement is shown in Figure 4 shown.

[0049] According to the above joint forms and welding methods, the relevant processes used are shown in Table 3.

[0050] Table 3 Implementation case data

[0051]

[0052] The base welding material involved in the present invention is CHT711 flux-cored welding wire with a diameter of 1.2 mm. CO2 gas shielded welding is adopted with reverse polarity of DC. The filling welding adopts submerged arc welding method with a shielding gas of 80% Ar+20% CO2. The welding wire is ER50-6 flux-cored welding wire with a diameter of 5 mm.

[0053] The implementation effects of the present invention are as follows:

[0054] Appearance inspection: The weld surface is well formed and there are no welding defects.

[0055] Non-destructive testing of welds: Ultrasonic testing is used, and the assessment level is II, and the intrinsic quality of the welds is qualified.

[0056] This scheme is adopted to carry out full penetration welding of the corner joints of Q355ME hot-rolled H-shaped steel flanges, and the quality of the welded joints is guaranteed to meet the use requirements of the project.

[0057] The above is only an explanation of the preferred embodiments of the present invention, and the above technical features can be arbitrarily combined to form multiple embodiments of the present invention.

[0058] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the concept and technical solution of the present invention, or the 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 full penetration welding method for Q355ME hot-rolled H-beam fillet with flange thickness of 30-50 mm, characterized in that: The welding method comprises the following steps: 1) According to the welding joint form and the thickness of the parent material, propose reasonable groove form and welding form; 2) Determine the preheating temperature before welding and the insulation temperature after welding to avoid cold crack defects in the joint; 3) Select appropriate welding materials according to the joint form, groove form and welding form; 4) Propose appropriate welding process parameters and perform welding operations.

2. The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm as claimed in claim 1, characterized in that: The welding joint is in the form of a T-shaped corner joint or an L-shaped corner joint.

3. The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm as claimed in claim 2, characterized in that: Before welding, the welding wire is kept warm and dried in a drying oven for 2-4 hours, and the insulation temperature is ≤200°C.

4. The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm as claimed in claim 3, characterized in that: The base material is preheated before welding, and the preheating temperature is ≥ 60°C.

5. The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm as claimed in claim 4, characterized in that: The welding operation adopts multi-layer and multi-pass surfacing welding, and the interlayer temperature is ≤250°C.

6. The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm as claimed in claim 5, characterized in that: After welding, the welded joint is subjected to insulation treatment, the insulation temperature is 170-210° C., and the insulation time is ≥2h.

7. The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm as claimed in claim 6, characterized in that: The welding adopts a double-sided V-shaped groove with a groove angle of 50-70 degrees. The welding is first performed as a base welding, then a filling welding, and finally a cover welding.

8. The full penetration welding method for Q355ME hot-rolled H-shaped steel corner joint with a flange thickness of 30-50 mm as claimed in claim 7, characterized in that: The base welding adopts CO2 gas shielded welding, the welding wire is CHT711 flux-cored welding wire, the welding wire diameter is 1.1-1.3mm, the welding current is 190-230A, the voltage is 27-31V, the welding speed is 15-22cm / min, and the line energy is 14.0-28.5kJ / cm.

9. The full penetration welding method for Q355ME hot-rolled H-shaped steel fillet with a flange thickness of 30-50 mm as claimed in claim 7, characterized in that: The filling welding adopts a submerged arc welding method, the shielding gas is 80% Ar+20% CO2, the welding wire is ER50-6 flux-cored welding wire, the welding wire diameter is 4-6mm, the welding current is 600-800A, the welding voltage is 29-35V, the welding speed is 45-65cm / min, and the line energy is 16.1-37.3kJ / cm.

10. The full penetration welding method for Q355ME hot-rolled H-shaped steel fillet with a flange thickness of 30-50 mm as claimed in claim 7, characterized in that: The cap welding adopts submerged arc welding method, the protective gas is 80% Ar+20% CO2, the welding wire is ER50-6 flux-cored welding wire, the welding wire diameter is 4-6mm, the welding current is 650-780A, the welding voltage is 35-38V, the welding speed is 45-65cm / min, and the line energy is 21.0-39.5kJ / cm.

Images