A low-hydrogen type backing welding electrode and a preparation method thereof

Abstract

The application provides a low-hydrogen type backing welding electrode and a preparation method thereof, and relates to the field of welding materials. The low-hydrogen type backing welding electrode comprises a steel core and a coating material, the coating material is coated on the surface of the steel core, and the coating material comprises the following raw materials in total 100 parts by mass: 6-10 parts of rutile, 35-40 parts of marble, 6-12 parts of fluorite, 10-15 parts of ferrosilicon, 5-9 parts of medium-carbon ferromanganese, 1-3 parts of aluminum-magnesium alloy, 0.3-1 part of soda ash, 1-3 parts of feldspar, 3-7 parts of quartz stone and 0.5-1 part of sodium carboxymethyl cellulose. The low-hydrogen type backing welding electrode and the preparation method thereof improve the porosity resistance of the electrode through marble slagging and gas making, reduce the diffusion hydrogen through fluorite, adjust the melting point and tension of the welding slag through feldspar, make the weld metal form regular, and finally make the weld deposition metal have good penetration and good back forming effect through the deoxidation and denitrification of the medium-carbon ferromanganese and the aluminum-magnesium alloy.

Description

Technical Field

[0001] This invention relates to the field of welding materials, specifically to a low-hydrogen type root pass welding electrode and its preparation method. Background Technology

[0002] With the increasing demands of modern production and daily life, energy consumption is rising daily. Pipelines, as the primary means of energy transportation, are experiencing ever-increasing transport volumes. There are only two ways to increase pipeline transport capacity: increasing internal pressure or increasing pipe diameter. Both increasing pressure and diameter place high demands on pipeline welding. However, root pass welding is the most difficult, least efficient, and most challenging step in pipeline welding, making high-quality welding materials with excellent welding processability crucial. While argon arc welding is inefficient, gas-shielded wire welding is unsuitable for outdoor operations. Therefore, welding electrodes have become the most suitable choice for field welding. Currently used fiber-type welding electrodes, due to their high carbon, oxygen, and diffusible hydrogen content in the weld, result in poor weld penetration, poor weld back surface formation, and poor compatibility with the inner surface of the pipe, making them unsuitable for current and future engineering requirements. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention provides a low-hydrogen type root pass welding electrode and its preparation method, so as to improve the technical problem that the weld metal has a high diffusible hydrogen content after welding, resulting in poor penetration of the weld metal and poor back-side formation.

[0004] To achieve the above and other related objectives, the present invention provides a low-hydrogen type root pass welding electrode, comprising a steel core and a coating material, wherein the coating material is coated on the surface of the steel core, and the coating material comprises the following raw materials in parts by weight:

[0005] Rutile 6-10 parts, marble 35-40 parts, fluorite 6-12 parts, ferrosilicon 10-15 parts, medium carbon manganese ferromanganese 5-9 parts, aluminum-magnesium alloy 1-3 parts, soda ash 0.3-1 part, feldspar 1-3 parts, quartz 3-7 parts, sodium carboxymethyl cellulose 0.5-1 part.

[0006] In one example of the low-hydrogen type root pass welding electrode of the present invention, the rutile contains 85% or more titanium dioxide; the marble contains 96% or more calcium carbonate; the fluorite contains 95% or more calcium fluoride; the ferrosilicon contains 40-50% silicon; the medium-carbon ferromanganese contains 78-83% manganese; the aluminum-magnesium alloy contains 45-55% aluminum and 45-55% magnesium; the soda ash contains 95% or more sodium carbonate; the feldspar contains 63-73% silicon dioxide and 15-24% alumina; and the quartz contains 95% or more silicon dioxide.

[0007] In one example of the low-hydrogen type root pass welding electrode of the present invention, the rutile has a particle size of 40-80 mesh, the marble has a particle size of 40-80 mesh, the fluorite has a particle size of 40-80 mesh, the ferrosilicon has a particle size of 40-80 mesh, the medium-carbon ferromanganese has a particle size of 40-80 mesh, the aluminum-magnesium alloy has a particle size of 40-80 mesh, the soda ash has a particle size of 80-120 mesh, the feldspar has a particle size of 40-80 mesh, the quartz has a particle size of 40-80 mesh, and the sodium carboxymethyl cellulose has a particle size of 80-120 mesh.

[0008] In one example of the low-hydrogen type root pass welding electrode of the present invention, the diameter of the steel core is 2.5 to 4.0 mm.

[0009] In one example of the low-hydrogen type root pass welding electrode of the present invention, the mass of the coating material is 30-35% of the sum of the mass of the coating material and the mass of the steel core.

[0010] In one example of the low-hydrogen type root pass welding electrode of the present invention, the diameter of the low-hydrogen type root pass welding electrode is 2.5 to 5.0 mm.

[0011] This invention also provides a method for preparing a low-hydrogen type root pass welding electrode, comprising the following steps:

[0012] S1. Weigh each raw material;

[0013] S2. After weighing the raw materials, add them to the binder and mix them evenly to obtain a mixture of drug coating materials.

[0014] S3. The coating material mixture is pressed onto the surface of the steel core to obtain the first welding electrode;

[0015] S4. Dry the first welding electrode to obtain the low-hydrogen type root pass welding electrode.

[0016] In one example of the preparation method of the low-hydrogen type root pass welding electrode of the present invention, in step S2, the binder is a water glass binder, and the mass of the binder is 20-23% of the total mass of the coating material mixture.

[0017] In one example of the preparation method of the low-hydrogen type root pass welding electrode of the present invention, in step S3, the pressure during pressure coating is 8 to 12 MPa.

[0018] In one example of the preparation method of the low-hydrogen type root pass welding electrode of the present invention, in step S4, the drying temperature is 350-380°C and the drying time is 1-2 hours.

[0019] This invention relates to a low-hydrogen root pass welding electrode and its preparation method. By using marble to create slag and gas, the electrode's resistance to porosity is improved. Fluorite is used to reduce diffusible hydrogen. Feldspar is used to adjust the melting point and tension of the weld slag, resulting in a regular weld metal formation. Medium-carbon ferromanganese and aluminum-magnesium alloys are used for deoxidation and denitrification, ultimately giving the weld deposited metal good penetration and a good back pass formation effect. Detailed Implementation

[0020] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of the present invention is for describing specific implementation schemes and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0021] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0022] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as part of the scope of the invention.

[0023] This invention provides a low-hydrogen type root pass welding electrode, comprising a steel core and a coating material. The coating material is applied to the surface of the steel core. Based on the total mass fraction of the coating material, the coating material comprises the following raw materials:

[0024] Rutile 6-10 parts. The main component of rutile is titanium dioxide, which can stabilize the electric arc and reduce splashing. When combined with other slag-forming agents, it can improve slag removal. The weight of rutile can be any value within the range of 6-10 parts, such as 6 parts, 8 parts or 10 parts.

[0025] Marble 35-40 parts. Marble mainly serves to generate gas and slag. The weight of marble can be any value within the range of 35-40 parts, such as 35 parts, 38 parts, or 40 parts.

[0026] Fluorite 6 to 12 parts by weight. Fluorite mainly plays a role in slag formation. The weight of fluorite can be any value within the range of 6 to 12 parts.

[0027] Ferrosilicon 10-15 parts. Ferrosilicon is mainly used as a deoxidizer and alloying agent. The weight of ferrosilicon can be any value within the range of 10-15 parts, such as 10 parts, 12 parts or 15 parts.

[0028] Medium carbon ferromanganese 5 to 9 parts. Medium carbon ferromanganese is mainly used as a deoxidizer, alloying agent and desulfurizer. The weight parts of medium carbon ferromanganese can be any value in the range of 5 to 9 parts, such as 5 parts, 7 parts or 9 parts.

[0029] 1 to 3 parts of aluminum-magnesium alloy. Aluminum-magnesium alloy is mainly used for deoxidation and denitrification. The weight of magnesium alloy can be any value within the range of 1 to 3 parts, such as 1 part, 2 parts, or 3 parts.

[0030] Soda ash is used in a quantity of 0.3 to 1 part by weight. The main function of soda ash is to stabilize the electric arc. The weight of soda ash is 0.3 to 1 part, such as 0.3 parts, 0.6 parts or 1 part, etc., any value within the range of 0.3 to 1 part.

[0031] Feldspar 1-3 parts, mainly used for slag formation and arc stabilization, can adjust the melting point and tension of welding slag;

[0032] Quartz stone 3 to 7 parts. Quartz stone is mainly used for slag formation and arc stabilization. It can adjust the melting point and tension of welding slag. The weight of quartz stone can be any value within the range of 3 to 7 parts, such as 3 parts, 5 parts or 7 parts.

[0033] Sodium carboxymethyl cellulose (SMC) is added in the amount of 0.5 to 1 part. Sodium carboxymethyl cellulose increases the fluidity of the flux powder, making it easier to evenly coat the welding electrode onto the steel core surface and improving the crack resistance of the electrode coating. The weight of sodium carboxymethyl cellulose can be any value within the range of 0.5 to 1 part, such as 0.5 parts, 0.8 parts, or 1 part.

[0034] In one example of the low-hydrogen type root pass welding electrode of the present invention, the rutile contains 85% or more titanium dioxide; the marble contains 96% or more calcium carbonate; the fluorite contains 95% or more calcium fluoride; the ferrosilicon contains 40-50% silicon; the medium-carbon ferromanganese contains 78-83% manganese; the aluminum-magnesium alloy contains 45-55% aluminum and 45-55% magnesium; the soda ash contains 95% or more sodium carbonate; the feldspar contains 63-73% silicon dioxide and 15-24% alumina; and the quartz contains 95% or more silicon dioxide.

[0035] In one example of the low-hydrogen type root pass welding electrode of the present invention, the rutile has a particle size of 40-80 mesh, the marble has a particle size of 40-80 mesh, the fluorite has a particle size of 40-80 mesh, the ferrosilicon has a particle size of 40-80 mesh, the medium-carbon ferromanganese has a particle size of 40-80 mesh, the aluminum-magnesium alloy has a particle size of 40-80 mesh, the soda ash has a particle size of 80-120 mesh, the feldspar has a particle size of 40-80 mesh, the quartz has a particle size of 40-80 mesh, and the sodium carboxymethyl cellulose has a particle size of 80-120 mesh. The particle size of the soda ash and the sodium carboxymethyl cellulose can be any value between 80 and 120 mesh, such as 80 mesh, 100 mesh, 110 mesh, 120 mesh, etc., and the particle size of the other components can be any value between 40 and 80 mesh, such as 40 mesh, 50 mesh, 60 mesh, 70 mesh, 80 mesh, etc.

[0036] In one example of the low-hydrogen type root pass welding electrode of the present invention, the diameter of the steel core is 2.5 to 4.0 mm. The diameter of the steel core can be any value within the range of 2.5 to 4.0 mm, for example: 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm.

[0037] In one example of the low-hydrogen type root pass welding electrode of the present invention, the mass of the coating material is 30-35% of the sum of the mass of the coating material and the mass of the steel core, for example, any value within the range of 30-35%, such as 30%, 32%, 34%, 35%, etc.

[0038] In one example of the low-hydrogen type root pass welding electrode of the present invention, the diameter of the low-hydrogen type root pass welding electrode is 2.5 to 5.0 mm, for example, any value in the range of 2.5 to 5.0 mm such as 2.5 mm, 3.0 mm, 4.0 mm, 5.0 mm, etc.

[0039] This invention also provides a method for preparing a low-hydrogen type root pass welding electrode, comprising the following steps:

[0040] S1. Weigh each raw material;

[0041] S2. After weighing the raw materials, add them to the binder and mix them evenly to obtain a mixture of drug coating materials.

[0042] S3. The coating material mixture is pressed onto the surface of the steel core to obtain the first welding electrode;

[0043] S4. Dry the first welding electrode to obtain the low-hydrogen type root pass welding electrode.

[0044] In one example of the preparation method of the low-hydrogen type root pass welding electrode of the present invention, in step S2, the binder is a water glass binder, and the mass of the binder is 20-23% of the total mass of the coating material mixture, for example, any value in the range of 20-23%, such as 20%, 21%, 22%, 23%, etc.

[0045] In one example of the preparation method of the low-hydrogen type root pass welding electrode of the present invention, in step S3, the pressure during pressure coating is 8 to 12 MPa, for example, any value in the range of 8 to 12 MPa such as 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, etc.

[0046] In one example of the preparation method of the low-hydrogen type root pass welding electrode of the present invention, in step S4, the drying temperature is 350-380℃, for example, any value within the range of 350-380℃ such as 350℃, 360℃, 370℃, 380℃; the drying time is 1-2h, for example, any value within the range of 1h, 1.3h, 1.5h, 1.8h, 2h, etc.

[0047] Different proportions of the above raw materials can constitute different embodiments, as shown in the following examples:

[0048] Example 1

[0049] The mass fractions of each component in the drug coating material are as follows: rutile 6 parts, marble 38 parts, fluorite 9 parts, ferrosilicon 10 parts, medium carbon manganese ferromanganese 5 parts, aluminum-magnesium alloy 3 parts, soda ash 1 part, feldspar 1 part, quartz 7 parts, and sodium carboxymethyl cellulose 0.8 parts.

[0050] Weigh each raw material;

[0051] After weighing, the raw materials are added to the water glass binder and mixed evenly to obtain a drug coating material mixture, wherein the mass of the water glass binder accounts for 20% of the total mass of the drug coating material mixture;

[0052] The coating material mixture is press-coated onto the surface of the steel core at a pressure of 8 MPa. The core diameter is 4.0 mm and the steel core material is H08A, thus obtaining the first welding electrode.

[0053] The first welding electrode is dried at 350°C for 1 hour to obtain the low-hydrogen root pass welding electrode, wherein the mass of the coating material mixture accounts for 35% of the total mass of the low-hydrogen root pass welding electrode, and the diameter of the low-hydrogen root pass welding electrode is 5 mm.

[0054] Example 2

[0055] The mass fractions of each component in the drug coating material are as follows: rutile 8 parts, marble 40 parts, fluorite 12 parts, ferrosilicon 13 parts, medium carbon manganese ferromanganese 7 parts, aluminum-magnesium alloy 2 parts, soda ash 0.6 parts, feldspar 2 parts, quartz 5 parts, and sodium carboxymethyl cellulose 0.5 parts.

[0056] Weigh each raw material;

[0057] After weighing, the raw materials are added to the water glass binder and mixed evenly to obtain a drug coating material mixture, wherein the mass of the water glass binder accounts for 23% of the total mass of the drug coating material mixture;

[0058] The coating material mixture is press-coated onto the surface of the steel core at a pressure of 12 MPa. The core diameter is 3.2 mm and the steel core material is H08A, thus obtaining the first welding electrode.

[0059] The first welding electrode is dried at 360°C for 1.5 hours to obtain the low-hydrogen type root pass welding electrode, wherein the mass of the coating material mixture accounts for 33% of the total mass of the low-hydrogen type root pass welding electrode, and the low-hydrogen type root pass welding electrode is 4 mm thick.

[0060] Example 3

[0061] The mass fractions of each component in the drug coating material are as follows: rutile 10 parts, marble 35 parts, fluorite 6 parts, ferrosilicon 15 parts, medium carbon manganese ferromanganese 9 parts, aluminum-magnesium alloy 1 part, soda ash 0.3 parts, feldspar 3 parts, quartz 3 parts, and sodium carboxymethyl cellulose 1 part.

[0062] Weigh each raw material;

[0063] After weighing, the raw materials are added to the water glass binder and mixed evenly to obtain a drug coating material mixture, wherein the mass of the water glass binder accounts for 21% of the total mass of the drug coating material mixture;

[0064] The coating material mixture is press-coated onto the surface of the steel core at a pressure of 10 MPa. The core diameter is 2.5 mm and the steel core material is H08A, thus obtaining the first welding electrode.

[0065] The first welding electrode is dried at 380°C for 2 hours to obtain the low-hydrogen type root pass welding electrode, wherein the mass of the coating material mixture accounts for 30% of the total mass of the low-hydrogen type root pass welding electrode, and the low-hydrogen type root pass welding electrode has a diameter of 3.2 mm.

[0066] The low-hydrogen type root pass welding electrode of the present invention was used to conduct various welding tests on the welding wires obtained in Examples 1-3 above, according to relevant standards.

[0067] The chemical composition of the weld deposited metal in the welding tests of each embodiment is shown in Table 1 below:

[0068] Table 1 Welding parameters and flaw detection results

[0069]

[0070] The mechanical properties of the weld metal and the diffusible hydrogen content of each embodiment are shown in Table 2 below:

[0071] Table 2 Mechanical properties and diffusible hydrogen content of the deposited metal

[0072]

[0073]

[0074] The results of the three impact energy tests on the weld metal in each embodiment are shown in Table 3 below:

[0075] Table 3. Results of Impact Energy Test of Deposited Metal

[0076]

[0077] The weldability and flaw detection results of the weld metal in each embodiment are shown in Table 4 below.

[0078]

[0079] The test results of Examples 1 to 3 show that the low-hydrogen welding electrode for root pass welding of the present invention has good all-position welding processability, stable mechanical properties, low diffusible hydrogen, and no defects in root pass welding flaw detection.

[0080] This invention relates to a low-hydrogen welding electrode for root pass welding and its preparation method. It improves the electrode's resistance to porosity by using marble for slag and gas generation, reduces diffusible hydrogen by using fluorite, adjusts the melting point and tension of the welding slag by using feldspar to ensure regular weld metal formation, and deoxidizes and denitrifies the weld metal using medium-carbon ferromanganese and aluminum-magnesium alloy, ultimately resulting in good penetration and excellent back-side forming effect. Therefore, this invention effectively overcomes some practical problems in the prior art, thus having high utilization value and practical significance. The above embodiments are merely illustrative of the principles and effects of this invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of this invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed in this invention should still be covered by the claims of this invention.

Claims

1. A low-hydrogen type root pass welding electrode, characterized in that, It includes a steel core and a coating material, wherein the coating material is applied to the surface of the steel core, and the coating material is composed of the following raw materials in parts by weight: The composition includes 6-10 parts rutile, 35-40 parts marble, 6-12 parts fluorite, 10-15 parts ferrosilicon, 5-9 parts medium-carbon ferromanganese, 1-3 parts aluminum-magnesium alloy, 0.3-1 part soda ash, 1-3 parts feldspar, 3-7 parts quartz, and 0.5-1 part sodium carboxymethyl cellulose; the mass of the coating material is 30-35% of the sum of the mass of the coating material and the mass of the steel core.

2. The low-hydrogen root pass welding electrode according to claim 1, characterized in that, The rutile contains 85% or more titanium dioxide; the marble contains 96% or more calcium carbonate; the fluorite contains 95% or more calcium fluoride; the ferrosilicon contains 40-50% silicon; the medium-carbon ferromanganese contains 78-83% manganese; the aluminum-magnesium alloy contains 45-55% aluminum and 45-55% magnesium; the soda ash contains 95% or more sodium carbonate; the feldspar contains 63-73% silicon dioxide and 15-24% alumina; and the quartz contains 95% or more silicon dioxide.

3. The low-hydrogen type root pass welding electrode according to claim 1, characterized in that, The rutile has a particle size of 40-80 mesh, the marble has a particle size of 40-80 mesh, the fluorite has a particle size of 40-80 mesh, the ferrosilicon has a particle size of 40-80 mesh, the medium-carbon ferromanganese has a particle size of 40-80 mesh, the aluminum-magnesium alloy has a particle size of 40-80 mesh, the soda ash has a particle size of 80-120 mesh, the feldspar has a particle size of 40-80 mesh, the quartz has a particle size of 40-80 mesh, and the sodium carboxymethyl cellulose has a particle size of 80-120 mesh.

4. The low-hydrogen root pass welding electrode according to claim 3, characterized in that, The diameter of the steel core is 2.5~4.0mm.

5. The low-hydrogen root pass welding electrode according to claim 1, characterized in that, The diameter of the low-hydrogen type root pass welding electrode is 2.5~5.0mm.

6. A method for preparing a low-hydrogen type root pass welding electrode as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Weigh each raw material; S2. After weighing, add the binder to each raw material and mix evenly to obtain a mixture of drug coating materials; S3. The coating material mixture is pressed onto the surface of the steel core to obtain the first welding electrode; S4. Dry the first welding electrode to obtain the low-hydrogen type root pass welding electrode.

7. The method for preparing the low-hydrogen type root pass welding electrode according to claim 6, characterized in that, In step S2, the adhesive is a water glass adhesive, and the mass of the adhesive is 20-23% of the total mass of the coating material mixture.

8. The method for preparing the low-hydrogen type root pass welding electrode according to claim 6, characterized in that, In step S3, the pressure during pressure coating is 8~12MPa.

9. The method for preparing the low-hydrogen type root pass welding electrode according to claim 6, characterized in that, In step S4, the drying temperature is 350~380℃ and the drying time is 1~2h.

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