Double-wire electro-gas welding process for steel for high heat input welding

Abstract

The invention discloses a double-wire electro-gas welding process for high heat input welding steel, which comprises the following steps: (1) the high heat input welding steel with the thickness of 70-80mm and the tensile strength of 510MPa is adopted, (2) two kinds of flux-cored wires are selected as welding materials and are respectively a front flux-cored wire and a rear flux-cored wire, (3) a groove form is a V-shaped groove, and the groove angle is 19-22 degrees; preheating is not performed before welding, single-pass welding is performed, and single-side welding and double-side forming are performed; according to the welding method, double-wire electro-gas welding is adopted, the welding heat input quantity is 720-810 kJ / cm, according to a front wire, the welding current is 360-370 A, the arc voltage is 33-36 V, and the welding speed is 2.60-2.70 cm / min; and for the rear wire, the welding current is 475-485A, the arc voltage is 43-45V, and the welding speed is 2.60-2.70 cm / min. According to the method, it is ensured that the mechanical property of a welded joint meets the requirement.

Description

Technical Field

[0001] The invention belongs to the field of steel material welding, and particularly to the technical field of double-wire gas-electric vertical welding of a welding joint using 70-80mm thick steel with excellent comprehensive performance and tensile strength of 510MPa and high-energy-line welding. Background Art

[0002] With the increasing use of thick-gauge high-strength steel in large structures such as ships and offshore platforms, downstream shipbuilding companies using low-alloy high-strength steel are increasingly adopting high-efficiency welding methods to improve welding efficiency and reduce costs. Many shipyards have also gradually begun to test and promote the ultra-high heat input welding method of double-wire gas-electric vertical welding. In this context, research and development of wide and thick plates of different specifications and strength levels suitable for ultra-high heat input welding has become a research and development hotspot in the steel industry.

[0003] In the manufacturing process of large equipment such as ships and offshore platforms, welding processes account for 30% of the total workload and 15% of the manufacturing costs. Therefore, how to improve welding efficiency and reduce welding costs in the welding process has become the key to the preparation of ships and offshore platforms. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a double-wire gas-electric vertical welding process for high-wire energy welding steel in view of the shortcomings of the above-mentioned prior art, so as to ensure that the mechanical properties of the welded joint meet the requirements.

[0005] The technical solution of the present invention to solve the above technical problems is: a double-wire gas-electric vertical welding process for high-line energy welding steel, comprising: (1) Welded steel plate Use 70-80mm thick steel with tensile strength of 510MPa and high energy input welding (2) Welding materials The welding material uses two kinds of flux-cored welding wires, namely, front flux-cored welding wire and rear flux-cored welding wire, wherein the chemical composition and weight percentage of the front flux-cored welding wire are: C: ≤0.10%, Mn: ≤1.0%, Si: ≤0.15%, S: ≤0.015%, P: ≤0.025%, Ni: 2.00-3.00%, Cu: 0.05-0.15%, Mo: ≤0.8%, the balance is Fe and unavoidable impurities; the chemical composition and weight percentage of the rear flux-cored welding wire are: C: ≤0.10%, Mn: ≤1.2%, Si: ≤0.2%, S: ≤0.015%, P: ≤0.025%, Ni: 0.80-1.80%, Cu: 0.05-0.15%, Mo: 1.00-2.00%, the balance is Fe and unavoidable impurities; (3) Welding parameters Bevel form: V-shaped bevel, bevel angle is 19-22°; No preheating before welding, single pass welding, single-sided welding and double-sided forming; Using double-wire gas-electric vertical welding, the welding heat input is 720-810kJ / cm: Front wire: welding current 360-370A, arc voltage 33-36V, welding speed 2.60-2.70cm / min; Rear wire: welding current 475-485A, arc voltage 43-45V, welding speed 2.60-2.70cm / min.

[0006] The present invention further defines the scheme: Preferably, the chemical composition and weight percentage of the steel for high input energy welding in (1) are C: ≤0.18%, Mn: 0.90-1.60%, Si: 0.20-0.50%, S: ≤0.01%, P: ≤0.01%, Ni: 0.15-0.40%, Mo: 0.03-0.08%, Cu: 0.15-0.35%, and the balance is Fe and unavoidable impurities.

[0007] Preferably, the steel for high heat input welding in (1) has a yield strength of ≥390 MPa, a tensile strength of ≥510 MPa, an elongation of ≥20%, and an impact energy KV 2 of ≥55 J at -40°C.

[0008] Preferably, the welding material is two types of flux-cored welding wires with a diameter of Φ1.6 mm, the low-temperature impact energy of the deposited metal at -20°C KV 2 ≥47J, and the tensile strength of the welding wire ≥550MPa.

[0009] Preferably, the groove form in (3) is a V-shaped groove, the groove angle is 19-22°, the blunt edge size is 0-1mm, and the groove assembly leaves a gap of 10-13mm.

[0010] Preferably, in (3), no preheating is performed before welding, single-pass welding is performed, the front side of the double-sided formed groove is a water-cooled copper slider, and the back side is a ceramic liner (TC-F2), the protective gas is CO2 (99.9%), and the gas flow rate is 15 to 25 L / min.

[0011] The beneficial effects of the present invention are: The present invention adopts an easy-to-operate double-wire gas-electric vertical welding process to weld steel with a tensile strength of 510MPa and high input energy for welding. The welding heat input reaches 720kJ-810kJ / cm, and can still ensure that the low-temperature impact energy KV2 of the welded joint at -20°C is ≥41J, the tensile strength of the welded joint is ≥510MPa, the side bending d=4a, 180°, and there is no crack in the welded joint. The welded joint formed by the welding process has good comprehensive performance and is suitable for welding 70~80mm thick steel with a tensile strength of 510MPa and high input energy for welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of double-wire gas-electric vertical welding of the present invention; Figure 2 Schematic diagram of welding groove in the present invention; Figure 3 Schematic diagram of the weld in the present invention. DETAILED DESCRIPTION Example

[0013] This embodiment provides a double-wire gas-electrode vertical welding process for high-energy-line welding steel, comprising: (1) Welded steel plate Use steel for high-energy-input welding with a tensile strength of 510 MPa, whose chemical composition and weight percentage are C: ≤0.18%, Mn: 0.90-1.60%, Si: 0.20-0.50%, S: ≤0.01%, P: ≤0.01%, Ni: 0.15-0.40%, Mo: 0.03-0.08%, Cu: 0.15-0.35%, and the balance is Fe and unavoidable impurities; its yield strength is ≥390 MPa, tensile strength is ≥510 MPa, elongation is ≥20%, and the impact energy KV2 at -40℃ is ≥55J. The welding test plate combination is 70mm+70mm, and the test plate size is 800mm (length) × 200mm (width) × 70mm (thickness); (2) Welding materials The above welding materials use two kinds of flux-cored welding wires with a diameter of Φ1.6mm, the low-temperature impact energy of the deposited metal at -20℃ KV2≥47J, the tensile strength of the welding wire ≥550MPa, and the two kinds of flux-cored welding wires are respectively the front flux-cored welding wire and the rear flux-cored welding wire, wherein the chemical composition and weight percentage of the front flux-cored welding wire are: C: 0.08%, Mn: 0.09%, Si: 0.13%, S: 0.12%, P: 0.022%, Ni: 2.00%, Cu: 0.05%, Mo: 0.75%, and the balance is Fe and unavoidable impurities; the chemical composition and weight percentage of the rear flux-cored welding wire are: C: 0.08%, Mn: 1.1%, Si: 0.18%, S: 0.013%, P: 0.025%, Ni: 1.20%, Cu: 0.08%, Mo: 1.23%, and the balance is Fe and unavoidable impurities; (3) Welding parameters Groove form: V-shaped groove, groove angle is 20°, blunt edge size is 0mm, groove assembly leaves 11-12mm gap; No preheating before welding, single-pass welding, single-sided welding and double-sided forming, water-cooled copper slider on the front of the groove, ceramic liner (TC-F2) on the back, shielding gas is CO 2 (99.9%), gas flow rate is 22L / min; Using double-wire gas-electric vertical welding, the welding heat input is 742kJ / cm: Front wire: welding current 365A, arc voltage 34V, welding speed 2.65cm / min; Rear wire: welding current 475A, arc voltage 43V, welding speed 2.65cm / min. Example

[0014] This embodiment provides a double-wire gas-electrode vertical welding process for high-energy-line welding steel, which is different from the embodiment 1 in that it includes: (1) Welded steel plate The welding test plate combination is 80mm+80mm, and the test plate size is 800mm (length) × 200mm (width) × 80mm (thickness); (2) Welding materials The welding materials are two kinds of flux-cored welding wires with a diameter of Φ1.6mm, the low-temperature impact energy of the deposited metal at -20℃ KV2≥47J, the tensile strength of the welding wire ≥550MPa, and the two kinds of flux-cored welding wires are respectively the front flux-cored welding wire and the rear flux-cored welding wire, wherein the chemical composition and weight percentage of the front flux-cored welding wire are: C: 0.10%, Mn: 0.07%, Si: 0.15%, S: 0.011%, P: 0.021%, Ni: 2.35%, Cu: 0.078%, Mo: 0.6%, and the balance is Fe and unavoidable impurities; the chemical composition and weight percentage of the rear flux-cored welding wire are: C: 0.09%, Mn: 1.0%, Si: 0.15%, S: 0.011%, P: 0.021%, Ni: 1.15%, Cu: 0.09%, Mo: 1.33%, and the balance is Fe and unavoidable impurities; (3) Welding parameters Groove form: V-shaped groove, groove angle is 20°, blunt edge size is 0mm, groove assembly leaves 11-12mm gap; No preheating before welding, single-pass welding, single-sided welding and double-sided forming, water-cooled copper slider on the front of the groove, ceramic liner (TC-F2) on the back, shielding gas is CO 2 (99.9%), gas flow rate is 23L / min; Using double-wire gas-electric vertical welding, the welding heat input is 742kJ / cm: Front wire: welding current 365A, arc voltage 35V, welding speed 2.63cm / min; Rear wire: welding current 480A, arc voltage 44V, welding speed 2.63cm / min. Example

[0015] This embodiment provides a double-wire gas-electrode vertical welding process for high-energy-line welding steel, which is different from the embodiment 1 in that it includes: (1) Welded steel plate The welding test plate combination is 80mm+80mm, and the test plate size is 800mm (length) × 200mm (width) × 80mm (thickness); (2) Welding materials The above welding materials use two kinds of flux-cored welding wires with a diameter of Φ1.6mm, the low-temperature impact energy of the deposited metal at -20℃ KV2≥47J, the tensile strength of the welding wire ≥550MPa, and the two kinds of flux-cored welding wires are respectively the front flux-cored welding wire and the rear flux-cored welding wire, wherein the chemical composition and weight percentage of the front flux-cored welding wire are: C: 0.07%, Mn: 1.0%, Si: 0.11%, S: 0.012%, P: 0.022%, Ni: 3.00%, Cu: 0.15%, Mo: 0.8%, and the balance is Fe and unavoidable impurities; the chemical composition and weight percentage of the rear flux-cored welding wire are: C: 0.10%, Mn: 1.2%, Si: 0.2%, S: 0.015%, P: 0.025%, Ni: 1.80%, Cu: 0.15%, Mo: 2.00%, and the balance is Fe and unavoidable impurities; (3) Welding parameters Groove form: V-shaped groove, groove angle is 22°, blunt edge size is 1mm, groove assembly leaves 12-13mm gap; No preheating before welding, single-pass welding, single-sided welding and double-sided forming, water-cooled copper slider on the front of the groove, ceramic liner (TC-F2) on the back, shielding gas is CO 2 (99.9%), gas flow rate is 23L / min; Using double-wire gas-electric vertical welding, welding heat input 810kJ / cm: Front wire: welding current 370A, arc voltage 36V, welding speed 2.60cm / min; Rear wire: welding current 485A, arc voltage 45V, welding speed 2.60cm / min.

[0016] A 70-80 mm thick steel with a tensile strength of 510 MPa and high heat input welding was welded using the welding method of the above-mentioned Examples 1-3, and the mechanical properties of the welded joint were tested. The impact, tensile and bending properties of the welded joint are shown in Tables 1 and 2.

[0017] Table 1 Impact properties of welded joints

[0018] Table 2 Tensile and lateral bending properties of welded joints

[0019] It can be seen from Table 1 and Table 2 that the present invention adopts suitable welding materials and welding processes for welding (front wire: welding current 360-370A, arc voltage 33-36V, welding speed 2.60-2.70cm / min; rear wire: welding current 475~485A, arc voltage 43-45V, welding speed 2.60-2.70cm / min, welding heat input 720-810kJ / cm), the welding joint has excellent comprehensive performance, and the process implementation method provided by this patent is simple and has strong applicability.

[0020] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A twin-wire gas-electrode vertical welding process for high-energy-line welding steel, characterized in that: include: (1) Welded steel plate Use 70-80mm thick steel with tensile strength of 510MPa and high energy input welding (2) Welding materials The welding material uses two kinds of flux-cored welding wires, namely, front flux-cored welding wire and rear flux-cored welding wire, wherein the chemical composition and weight percentage of the front flux-cored welding wire are: C: ≤0.10%, Mn: ≤1.0%, Si: ≤0.15%, S: ≤0.015%, P: ≤0.025%, Ni: 2.00-3.00%, Cu: 0.05-0.15%, Mo: ≤0.8%, the balance is Fe and unavoidable impurities; the chemical composition and weight percentage of the rear flux-cored welding wire are: C: ≤0.10%, Mn: ≤1.2%, Si: ≤0.2%, S: ≤0.015%, P: ≤0.025%, Ni: 0.80-1.80%, Cu: 0.05-0.15%, Mo: 1.00-2.00%, the balance is Fe and unavoidable impurities; (3) Welding parameters Bevel form: V-shaped bevel, bevel angle is 19-22°; No preheating before welding, single pass welding, single-sided welding and double-sided forming; Using double-wire gas-electric vertical welding, the welding heat input is 720-810kJ / cm: Front wire: welding current 360-370A, arc voltage 33-36V, welding speed 2.60-2.70cm / min; Rear wire: welding current 475-485A, arc voltage 43-45V, welding speed 2.60-2.70cm / min.

2. The double-wire gas-electrode vertical welding process for high-energy-line welding steel according to claim 1, characterized in that: The chemical composition and weight percentage of the steel for medium and large heat input welding described in (1) are C: ≤0.18%, Mn: 0.90-1.60%, Si: 0.20-0.50%, S: ≤0.01%, P: ≤0.01%, Ni: 0.15-0.40%, Mo: 0.03-0.08%, Cu: 0.15-0.35%, and the balance is Fe and unavoidable impurities.

3. The double-wire gas-electrode vertical welding process for high-energy-line welding steel according to claim 1, characterized in that: The steel for medium to large heat input welding mentioned in (1) has a yield strength of ≥390 MPa, a tensile strength of ≥510 MPa, an elongation of ≥20%, and an impact energy KV 2 of ≥55 J at -40°C.

4. The double-wire gas-electrode vertical welding process for high-heat-input welding steel according to claim 1, characterized in that: The welding materials are two types of flux-cored welding wires with a diameter of Φ1.6 mm, the low-temperature impact energy of the deposited metal at -20°C KV 2 ≥47J, and the tensile strength of the welding wire ≥550MPa.

5. The double-wire gas-electrode vertical welding process for high-energy-line welding steel according to claim 1, characterized in that: The (3) middle groove form: V-shaped groove, the groove angle is 19-22°, the blunt edge size is 0-1mm, and the groove assembly leaves a gap of 10-13mm.

6. The double-wire gas-electrode vertical welding process for high-energy-line welding steel according to claim 1, characterized in that: In the above-mentioned (3), no preheating is performed before welding, and single-pass welding is performed. The front side of the double-sided formed groove is a water-cooled copper slider, and the back side is a ceramic liner (TC-F2). The protective gas is CO2 (99.9%), and the gas flow rate is 15 to 25 L / min.

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