Metal powder core welding wire and preparation method and application thereof

Abstract

The invention discloses a metal powder core welding wire and a preparation method and application thereof. A sheath of the metal powder core welding wire is made of low-carbon steel, and metal powder filled in the metal powder core welding wire comprises ferrosilicon powder, ferromanganese powder, nickel powder, molybdenum powder, ferrotitanium powder and iron powder. The preparation method of the metal powder core welding wire comprises the following steps that a low-carbon steel strip is rolled into a U-shaped groove, then the U-shaped groove is filled with evenly-mixed metal powder, then the U-shaped groove is closed, drawing is conducted, and the metal powder core welding wire is obtained. The metal powder cored wire is suitable for high-pressure dry welding of low-carbon steel plates in air environments with different pressures, has the advantages of relatively small welding heat input, stable welding process, high welding joint quality, no need of deslagging during thick plate welding, high welding efficiency and the like, and is suitable for large-scale industrial production and application.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater welding, and particularly relates to a metal cored wire and its preparation method and application. Background Art

[0002] Underwater welding technology is a special welding technology for welding operations in water, which has extensive applications in aspects such as undersea oil pipeline laying, sunken ship salvage, and marine accident rescue. Underwater high-pressure dry welding is a relatively common underwater welding method. When using this method for underwater welding, the part to be welded does not come into direct contact with water, so it can largely avoid the influence of the water environment on the welding process, making this welding method have the advantages of relatively fast welding speed, low diffusible hydrogen content, good welding quality, safety and reliability, etc. However, most of the filler materials used in traditional underwater high-pressure dry welding are electrodes, solid cored wires or flux cored wires suitable for use in land environments. These electrodes / wires have problems such as poor stability during the welding process and large welding spatter (which can lead to poor quality of the welded joint) when used in a high-pressure environment. Moreover, when welding medium-thick or thick plates using multi-layer and multi-pass processes in an underwater high-pressure environment, after each weld seam is completed, surface slag removal and impurity cleaning (preparing for the next process) are required, which will cause a significant increase in the time for underwater welding and repair, low welding efficiency, waste of the key time for welding and repair, and it is difficult to meet the requirements of practical applications.

[0003] Therefore, it is of great significance to develop a wire that has a stable welding process, high quality of the welded joint, does not require slag removal during thick plate welding, high welding efficiency, and is suitable for underwater high-pressure dry welding. Summary of the Invention

[0004] The purpose of the present invention is to provide a metal cored wire and its preparation method and application.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A metal cored wire, whose outer skin is made of low-carbon steel, and the metal powder filled inside includes ferrosilicon powder, ferromanganese powder, nickel powder, molybdenum powder, ferrotitanium powder and iron powder.

[0007] Preferably, the mass percentage content of the metal powder filled inside the metal cored wire is as follows:

[0008] Ferrosilicon powder: 10% - 15%;

[0009] Ferromanganese powder: 10% - 15%;

[0010] Nickel powder: 2% - 4%;

[0011] Molybdenum powder: 1% - 2%;

[0012] Ferrotitanium powder: 0.5% - 2%;

[0013] Iron powder: the balance.

[0014] Preferably, the ferrosilicon powder is 45 ferrosilicon powder, the mass percentage content of Si is 40% - 47%, the mass percentage content of C ≤ 0.2%, and the rest is Fe.

[0015] Preferably, the ferromanganese powder is low-carbon ferromanganese powder, the mass percentage content of Mn is 80% - 87%, the mass percentage content of C ≤ 0.4%, and the rest is Fe.

[0016] Preferably, the ferrotitanium powder is high-titanium ferrotitanium powder, the mass percentage content of Ti is 65% - 75%, the mass percentage content of C ≤ 0.2%, and the rest is Fe.

[0017] Preferably, the low-carbon steel is H08A steel.

[0018] Preferably, the thickness of the outer skin of the metal cored wire is 0.2 mm - 0.5 mm.

[0019] Preferably, the diameter of the metal cored wire is 1.2 mm - 1.6 mm.

[0020] A method for preparing the metal cored wire as described above includes the following steps: rolling a low-carbon steel strip into a U-shaped groove, then filling the uniformly mixed metal powder into the U-shaped groove, then closing the U-shaped groove, and then performing drawing to obtain the metal cored wire.

[0021] An application of the metal cored wire as described above in underwater high-pressure dry welding.

[0022] Preferably, the welding object of the underwater high-pressure dry welding is low-carbon steel.

[0023] The beneficial effects of the present invention are: the metal cored wire of the present invention is suitable for high-pressure dry welding of low-carbon steel plates in air environments with different pressures. It has the advantages of relatively small welding heat input, stable welding process, high quality of welding joints, no slag removal required during thick plate welding, and high welding efficiency, and is suitable for large-scale industrial production and application.

[0024] Specifically:

[0025] 1) The metal cored wire of the present invention contains ferrosilicon powder and ferromanganese powder. Mn and Si are mainly used for combined deoxidation and conditioning, which can significantly improve the strength and toughness of steel. The manganese element also has the function of desulfurization. The two can form a C-Mn-Si alloy system. The C-Mn-Si alloy system can improve the wear resistance and corrosion resistance of the weld metal to a certain extent, and the C-Mn-Si alloy system also has the advantage of low production cost;

[0026] 2) The metal cored wire of the present invention contains nickel powder, which can strengthen ferrite and refine pearlite in the weld seam, improving the impact toughness of the weld seam while ensuring that the weld seam has sufficient strength.

[0027] 3) The metal cored wire of the present invention contains molybdenum powder, which can improve the tempering stability of the weld seam, eliminate the residual stress in the weld seam during multi-layer and multi-pass welding, and thus improve the plasticity of the weld seam.

[0028] 4) The metal cored wire of the present invention contains ferro-titanium powder (its content needs to be strictly controlled), which can play a good role in deoxidation and degassing during the welding process, increase the A1 and A3 temperatures of the steel, and titanium can improve the plasticity and toughness of the weld seam in ordinary low-carbon steel, improving the mechanical properties of the weld seam.

[0029] 5) The metal cored wire of the present invention has the advantages of relatively small welding heat input (excellent welding effects can be achieved with a small heat input), stable welding process, high quality of the welded joint (when used for underwater hyperbaric dry welding of medium-thick or thick low-carbon steel plates, the tensile strength and impact toughness of the weld metal can reach 90% of the base metal), no slag removal required during thick plate welding (the slag is extremely little or there is no slag), high welding efficiency, and low production cost. It can be used for underwater hyperbaric dry welding of low-carbon steel plates, and its preparation method is simple, the raw materials are easy to obtain and widely sourced, making it suitable for large-scale industrial production and application. Description of the Drawings

[0030] Figure 1 It is a fluctuation diagram of the arc voltage and welding current within 1 s during welding of the metal cored wire of Example 1 and the solid wire ER50-6 of Comparative Example 1.

[0031] Figure 2 It is a physical diagram of the weld metal formed by welding with the metal cored wire of Example 1.

[0032] Figure 3 It is an SEM diagram of the weld metal formed by welding with the metal cored wire of Example 2. Detailed Embodiments

[0033] The present invention will be further explained and illustrated below in conjunction with specific embodiments.

[0034] The component contents of ferro-silicon powder, ferro-manganese powder and ferro-titanium powder in Examples 1 to 3 are as follows:

[0035] Ferro-silicon powder: 45 ferro-silicon powder, the mass percentage content of Si is 40% - 47%, the mass percentage content of C ≤ 0.2%, and the rest is Fe.

[0036] Ferromanganese powder: Low-carbon ferromanganese powder, with the mass percentage of Mn being 80% - 87%, the mass percentage of C ≤ 0.4%, and the rest being Fe.

[0037] Ferrotitanium powder: High-titanium ferrotitanium powder, with the mass percentage of Ti being 65% - 75%, the mass percentage of C ≤ 0.2%, and the rest being Fe.

[0038] Example 1:

[0039] A metal cored wire with a diameter of 1.6 mm and an outer skin thickness of 0.3 mm. The outer skin is made of H08A steel, and the mass percentage of the metal powder filled inside is as follows: Ferrosilicon powder: 12%; Ferromanganese powder: 11%; Nickel powder: 2%; Molybdenum powder: 1%; Ferrotitanium powder: 1%; Iron powder: 73%.

[0040] The preparation method of the above metal cored wire is as follows:

[0041] Roll an H08A steel strip with a width of 12 mm and a thickness of 0.3 mm into a U-shaped groove, then fill the uniformly mixed metal powder into the U-shaped groove, and then use a special seam welding machine for the wire to close the U-shaped groove (the cross-section is in an O shape), and then perform drawing until the diameter of the wire is 1.6 mm, thus obtaining the metal cored wire.

[0042] Welding test:

[0043] Use the metal cored wire of this example to weld low-carbon steel Q235 with a thickness of 10 mm. The specific operation is as follows: Place the plate to be welded into the pressure chamber, and introduce 0.5 MPa of compressed air into the pressure chamber to simulate the underwater high-pressure environment at a depth of 50 m. Before welding, open a 60° V-shaped groove on the plate to be welded. The groove has no blunt edge and no gap. Select CO 2 -Ar mixed gas (the volume ratio of CO 2 and Ar is 1:4) as the shielding gas, and the flow rate is 15 L / min - 25 L / min; The welding process parameters are: the welding current is 180 A - 280 A, the arc voltage is 24 V - 30 V, and the welding speed is 0.12 m / min - 0.15 m / min; The 10-mm-thick plate can be welded with two layers and one pass, and slag removal is not required during the welding process.

[0044] Example 2:

[0045] A metal cored wire with a diameter of 1.2 mm and an outer skin thickness of 0.2 mm. The outer skin is made of H08A steel, and the mass percentage of the metal powder filled inside is as follows: Ferrosilicon powder: 10%; Ferromanganese powder: 10%; Nickel powder: 2.5%; Molybdenum powder: 1%; Ferrotitanium powder: 0.5%; Iron powder: 76%.

[0046] The preparation method of the above metal cored wire is as follows:

[0047] Roll the H08A steel strip with a width of 12 mm and a thickness of 0.2 mm into a U-shaped groove, then fill the uniformly mixed metal powder into the U-shaped groove, and then use a seam welding machine dedicated to welding wire to close the U-shaped groove (the cross-section is O-shaped), and then perform drawing until the diameter of the welding wire is 1.2 mm, thus obtaining the metal cored wire.

[0048] Welding test:

[0049] Use the metal cored wire of this embodiment to weld the low-carbon steel Q235 with a thickness of 10 mm. The specific operation is as follows: Place the plate to be welded into the pressure chamber, and introduce 0.3 MPa of compressed air into the pressure chamber to simulate the underwater high-pressure environment at a depth of 30 m. Before welding, open a 45° V-shaped groove on the plate to be welded. The groove has no blunt edge and no gap, and select CO 2 -Ar mixed gas (the volume ratio of CO 2 and Ar is 1:4) as the shielding gas, and the flow rate is 15 L / min to 25 L / min; the welding process parameters are: the welding current is 150 A to 250 A, the arc voltage is 20 V to 28 V, and the welding speed is 0.12 m / min to 0.15 m / min; welding the 10 mm thick plate can be completed with two layers and one pass, and slag removal is not required during the welding process.

[0050] Example 3:

[0051] A metal cored wire with a diameter of 1.6 mm and an outer skin thickness of 0.3 mm. The outer skin is made of H08A steel, and the mass percentage content of the metal powder filled inside is as follows: ferrosilicon powder: 12%; ferromanganese powder: 13%; nickel powder: 3%; molybdenum powder: 1%; ferrotitanium powder: 1%; iron powder: 70%.

[0052] The preparation method of the above metal cored wire is as follows:

[0053] Roll the H08A steel strip with a width of 12 mm and a thickness of 0.3 mm into a U-shaped groove, then fill the uniformly mixed metal powder into the U-shaped groove, and then use a seam welding machine dedicated to welding wire to close the U-shaped groove (the cross-section is O-shaped), and then perform drawing until the diameter of the welding wire is 1.6 mm, thus obtaining the metal cored wire.

[0054] Welding test:

[0055] Use the metal cored wire of this embodiment to weld the low-carbon steel Q255 with a thickness of 12 mm. The specific operation is as follows: Place the plate to be welded into the pressure chamber, and introduce 0.5 MPa of compressed air into the pressure chamber to simulate the underwater high-pressure environment at a depth of 50 m. Before welding, open a 60° V-shaped groove on the plate to be welded. The groove has no blunt edge and no gap, and select CO 2 -Ar mixed gas (CO2 Using argon with a volume ratio of 1:4 as the shielding gas, the flow rate is 15 L / min to 25 L / min; the welding process parameters are: the welding current is 150 A to 250 A, the arc voltage is 20 V to 28 V, and the welding speed is 0.12 m / min to 0.15 m / min; a 12-mm-thick plate can be welded in two layers and one pass, and slag removal is not required during the welding process.

[0056] Comparative Example 1:

[0057] Solid wire ER50-6 (diameter 1.6 mm).

[0058] Welding test:

[0059] Welding Q235 low-carbon steel, with the welding parameters and environmental parameters being the same as those in Example 1.

[0060] Comparative Example 2:

[0061] Flux-cored wire E501T-1 (diameter 1.2 mm).

[0062] Welding test:

[0063] Welding Q235 low-carbon steel, with the welding parameters and environmental parameters being the same as those in Example 2.

[0064] Performance test:

[0065] 1) Using a data acquisition card to collect the arc voltage and welding current during the welding process of the metal-cored wire in Example 1 and the solid wire ER50-6 in Comparative Example 1, the fluctuation diagrams of the arc voltage and welding current of the metal-cored wire and the solid wire ER50-6 within 1 s of welding are as shown in Figure 1 (a is the solid wire ER50-6, b is the metal-cored wire), and the physical diagram of the weld metal formed by welding with the metal-cored wire is as shown in Figure 2 shown.

[0066] From Figure 1 and Figure 2 it can be seen that: when welding with the metal-cored wire, the fluctuations of the arc voltage and welding current are very small, the welding process is stable, the droplet transfer form is jet transfer, the weld metal formed by welding has good formation, without cracks, undercut and pores, while when welding with the solid wire ER50-6, the fluctuations of the arc voltage and welding current are very large, indicating that the metal-cored wire of the present invention is significantly more stable during the welding process compared with the solid wire ER50-6.

[0067] 2) The scanning electron microscope (SEM) diagram of the weld metal formed by welding with the metal-cored wire in Example 2 is as shown in Figure 3 shown.

[0068] FromFigure 3 It can be seen that the weld fusion is good, without obvious slag inclusions, cracks, pores, etc., indicating that the welded joints formed by welding with the metal cored wire of the present invention have high quality.

[0069] 3) The mechanical property test results of the weld metals formed by welding the metal cored wires of Examples 1 to 3, the solid cored wire ER50-6 of Comparative Example 1, and the flux cored wire E501T-1 of Comparative Example 2 are shown in the following table:

[0070] Table 1 Mechanical property test results of weld metals

[0071]

[0072]

[0073] Note:

[0074] Tensile strength: Tested with reference to "GB / T 2651-2023 Destructive tests on welds in metallic materials - Transverse tensile test".

[0075] Yield strength: Tested with reference to "GB / T 2651-2023 Destructive tests on welds in metallic materials - Transverse tensile test".

[0076] Impact toughness: Tested with reference to "GB / T 2650-2022 Destructive tests on welds in metallic materials - Impact test".

[0077] As can be seen from Table 1: The welded joints obtained by welding the metal cored wires of the present invention have excellent comprehensive mechanical properties, and their tensile strength, yield strength, and impact toughness can all reach the same or even higher values as those of the wires used in traditional land environments (for example: solid cored wire ER50-6 and flux cored wire E501T-1); in addition, combined with Figure 1 it can be seen that especially the metal cored wire of Example 1 is more stable during the welding process and has very little welding slag compared with the solid cored wire ER50-6 of Comparative Example 1, and can fully meet the actual application requirements of underwater high-pressure dry welding of low-carbon steel.

[0078] The above embodiments are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A metal powder cored welding wire, characterized in that: The outer skin is made of low carbon steel, and the metal powder filled inside includes ferrosilicon powder, ferromanganese powder, nickel powder, molybdenum powder, ferrotitanium powder and iron powder.

2. The metal powder cored welding wire according to claim 1, characterized in that: The mass percentage of the metal powder filled in the metal powder cored welding wire is as follows: Ferrosilicon powder: 10%~15%; Ferromanganese powder: 10%~15%; Nickel powder: 2% to 4%; Molybdenum powder: 1% to 2%; Ferrotitanium powder: 0.5% to 2%; Iron powder: balance.

3. The metal powder cored welding wire according to claim 1 or 2, characterized in that: The ferrosilicon powder is 45 ferrosilicon powder, the mass percentage of Si is 40% to 47%, the mass percentage of C is ≤0.2%, and the rest is Fe.

4. The metal powder cored welding wire according to claim 1 or 2, characterized in that: The ferromanganese powder is low-carbon ferromanganese powder, the mass percentage of Mn is 80% to 87%, the mass percentage of C is ≤0.4%, and the rest is Fe.

5. The metal powder cored welding wire according to claim 1 or 2, characterized in that: The titanium iron powder is high titanium iron powder, the mass percentage of Ti is 65% to 75%, the mass percentage of C is ≤0.2%, and the rest is Fe.

6. The metal powder cored welding wire according to claim 1 or 2, characterized in that: The low carbon steel is H08A steel.

7. The metal powder cored welding wire according to claim 1 or 2, characterized in that: The outer skin thickness of the metal powder cored welding wire is 0.2 mm to 0.5 mm; the diameter of the metal powder cored welding wire is 1.2 mm to 1.6 mm.

8. A method for preparing a metal powder cored welding wire as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: The low carbon steel strip is rolled into a U-shaped groove, and then the evenly mixed metal powder is filled into the U-shaped groove, and then the U-shaped groove is closed and drawn to obtain the metal powder cored welding wire.

9. Use of the metal powder cored welding wire as claimed in any one of claims 1 to 7 for underwater high pressure dry welding.

10. The use according to claim 9, characterized in that: The welding object of the underwater high-pressure dry welding is low-carbon steel.

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