Ultra-low hydrogen flux-cored welding wire and preparation method thereof

Abstract

The invention belongs to the technical field of welding materials, and specifically provides an ultra-low hydrogen flux-cored welding wire, comprising an outer skin and a flux core filled in the outer skin, wherein the outer skin is a steel strip; in terms of mass percentage, the flux core comprises 40-48% TiO2, 1.5-4.5% fluoride, 3-6% SiO2, 16-24% Mn, 2-6% Si, 3-6% Mg, 0.5-3% Ti, 2-6% arc stabilizer, and the balance is iron powder. The ultra-low hydrogen flux-cored welding wire provided by the invention has excellent welding process performance and mechanical properties, good weld formation, Akv≥100J under -20°C conditions, the diffused hydrogen content of the deposited metal is reduced to an ultra-low hydrogen level (≤4ml / 100g, mercury method), and the weld has good cold crack resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of welding materials, and in particular relates to a 50Kg-grade fine-grained steel ultra-low hydrogen flux-cored welding wire and a preparation method thereof. Background Art

[0002] With the advancement of flux-cored welding wire production process and technology, the quality of flux-cored welding wire products has been continuously improved. In particular, flux-cored welding wire has a series of advantages such as good processability and adjustable chemical composition of cladding metal, making it widely used in various fields such as ships, steel structures, bridges, etc. According to the statistical data of the China Welding Association, from 2011 to 2020, the output of welding materials in my country basically fluctuated between 4 million and 4.75 million tons, of which flux-cored welding wire products were 300,000 to 500,000 tons, and the proportion of flux-cored welding wire output to the total welding material output was stable in the range of 8-11%. Flux-cored welding wire is widely used in industries such as ships, bridges, and steel structures, but its application in important structures and industries with higher requirements such as marine engineering and pressure vessels is subject to certain restrictions. One of the important reasons is that the powder in the flux-cored welding wire is easy to absorb moisture, and the diffused hydrogen content of the cladding metal is much higher than that of solid welding wire or alkaline welding rod, which leads to limited promotion in industries such as pressure vessels, marine engineering, and bridges that have high requirements for low-temperature impact toughness and crack resistance.

[0003] Ultra-low hydrogen flux-cored welding wire is a high-standard welding wire that reaches the H5 level by reducing the diffusible hydrogen content of the cladding metal through production process upgrades, formula optimization or other special measures on the basis of ordinary flux-cored welding wire. Therefore, apart from product cost factors, ultra-low hydrogen flux-cored welding wire can cover the entire flux-cored welding wire market, especially in the fields of marine engineering, engineering machinery, pressure vessels, bridges, etc., which have wider requirements for strength levels, higher requirements for mechanical properties, especially low-temperature impact toughness, and stricter requirements for crack resistance. These are the main battlefields for ultra-low hydrogen flux-cored welding wire.

[0004] In the prior art, CN102873475A provides an ultra-low hydrogen and high-toughness acidic CO2 flux-cored welding wire and its preparation. The published scheme contains the requirement of "the welding wire should be subjected to online high-frequency heating and baking treatment during preparation". The production process is relatively complicated, difficult to control, and has low production efficiency.

[0005] CN111702371A provides an ultra-low hydrogen acidic flux-cored welding wire and a production method thereof. In the disclosed scheme, a steel strip with an oil content of less than 1.0g / 10kg is cleaned and then heated before the forming process, that is, the steel strip is heated to 80-120°C, then a U-shaped groove is rolled, and then the formula powder is added to the U-shaped groove and closed. After the closing is completed, the welding wire is reheated to 180-250°C online, and then the diameter is accurately drawn and reduced to a specified welding wire diameter through an eye die, and the residual wire drawing lubricant on the surface of the welding wire is cleaned, and finally a layer of wire feeding lubricant is evenly coated on the surface of the welding wire, and then the ultra-low hydrogen acidic flux-cored welding wire is wound through layers. Its production process requires heating the welding wire, and the production process is complicated, difficult to control, and the production efficiency is low. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems in the prior art that the production process of ultra-low hydrogen welding wire is complicated, difficult to control and has low production efficiency.

[0007] To this end, the present invention provides an ultra-low hydrogen flux-cored welding wire, comprising an outer skin and a flux core filled in the outer skin, wherein the outer skin is a steel strip; in terms of mass percentage, the flux core comprises 40-48% TiO2, 1.5-4.5% fluoride, 3-6% SiO2, 16-24% Mn, 2-6% Si, 3-6% Mg, 0.5-3% Ti, 2-6% arc stabilizer, and the balance is iron powder.

[0008] Specifically, the steel strip contains 0.2-0.4% Mn, ≤0.02% Si, 0.01-0.02% C, ≤0.01% S, ≤0.01% P, and the balance is Fe.

[0009] Specifically, the flux core accounts for 13.3-14.5% of the total mass of the flux-cored welding wire.

[0010] The present invention also provides a method for preparing the ultra-low hydrogen flux-cored welding wire, comprising the following steps:

[0011] (1) After weighing the raw materials of each component according to the proportion, mixing, sieving, drying and setting aside;

[0012] (2) Cleaning and drying the steel strip, rolling it into shape, and then drawing and reducing it to a specified diameter to obtain welding wire;

[0013] (3) Winding the welding wire and raw materials into the ultra-low hydrogen flux-cored welding wire.

[0014] Specifically, in the above step (2), the steel strip is heated to 90-130° C. for drying.

[0015] Specifically, in the above step (2), a lubricant is used for drawing, and after the drawing is completed, the lubricant remaining on the surface of the welding wire is removed.

[0016] Specifically, the lubricant includes graphite and molybdenum disulfide and does not contain organic matter, so that the lubricant has a good anti-moisture absorption effect and will not increase hydrogen due to the lubricant.

[0017] Specifically, after the drawing in the above step (2) is completed, the nano coating is evenly coated on the surface of the welding wire.

[0018] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0019] The ultra-low hydrogen flux-cored welding wire provided by the present invention has excellent welding process performance and mechanical properties, good weld formation, Akv≥100J under -20°C conditions, the diffusible hydrogen content of the deposited metal is reduced to an ultra-low hydrogen level (≤4ml / 100g, mercury method), and the weld has good cold crack resistance. DETAILED DESCRIPTION

[0020] The technical scheme in the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Although the representative embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be limited by the attached claims and their equivalents.

[0021] The present invention provides an ultra-low hydrogen flux-cored welding wire, comprising an outer skin and a flux core filled in the outer skin, wherein the outer skin is a steel strip; in terms of mass percentage, the flux core comprises 40-48% TiO2, 1.5-4.5% fluoride, 3-6% SiO2, 16-24% Mn, 2-6% Si, 3-6% Mg, 0.5-3% Ti, 2-6% arc stabilizer, and the balance is iron powder. The steel strip is a low-carbon, low-oil and low-impurity steel strip, and the proportion of each component in the steel strip is Mn0.2-0.4%, Si≤0.02%, C0.01-0.02%, S≤0.01%, P≤0.01%, and the balance is Fe. The flux core accounts for 13.3-14.5% of the total mass of the flux-cored welding wire.

[0022] Among them, TiO2 is mainly added in the form of rutile, ilmenite, and synthetic titanium compounds in the present invention, which can stabilize the welding arc, calm the molten pool, make the metal transition in a fine mist, refine the molten droplets, make the weld formation beautiful and fine, and provide good slag coverage. However, excessive use can easily reduce the mechanical properties and cause incomplete slag removal during vertical welding, so its content is controlled at 40-48%.

[0023] SiO2 is mainly added in the form of feldspar, quartz and silicate in the present invention. Silicon dioxide is used as a slag-forming agent to increase the activity of the slag, but excessive use will increase splashing, slag stickiness and significant explosion noise, so its content is controlled at 3-6%.

[0024] Silicon and manganese are mainly used to improve the strength of the deposited metal, and also play the role of deoxidation and desulfurization. With the increase of Mn content, the strength of the deposited metal increases, while the impact toughness first increases and then decreases. In the present invention, the combined deoxidation effect of silicon and manganese is better. Silicon and manganese are mainly added in the form of one or a combination of electrolytic manganese, metallic manganese, medium manganese, silicon-manganese alloy, and ferrosilicon. The manganese content is controlled at 16-24%, and the silicon content is controlled at 2-6%.

[0025] Fluoride can play a role in dehydrogenation during welding and can effectively reduce the diffusible hydrogen content of deposited metal. When it is less than 1.5%, the dehydrogenation effect is not obvious. However, since most fluorides have a low melting point and a high ionization point of fluorine, if more fluorides are added, the melting point of the slag will be too low, which is not conducive to vertical welding and will make the arc unstable. Therefore, its content is controlled at 1.5-4.5%. In the present invention, fluoride is mainly added in the form of sodium fluoride, cryolite, lithium fluoride, potassium fluorosilicate, etc.

[0026] Mg can effectively reduce the oxygen content in the deposited metal, purify the weld, improve the tensile strength and low-temperature impact toughness, and protect silicon manganese from transitioning to the deposited metal. If the Mg content is too low, the deoxidation effect is not obvious, the impact toughness is not high, and if the strong deoxidation is too high, the strength of the deposited metal is too high and the plasticity is poor, so its content is controlled at 3-6%. In the present invention, Mg is mainly added in the form of one or a combination of magnesium powder and magnesium-aluminum alloy.

[0027] Titanium can refine the grains and improve the low-temperature impact toughness of the deposited metal. Titanium is also a strong deoxidizer. Titanium deoxidizes mainly by combining with oxygen in a higher temperature zone. It is difficult for less titanium to transition to the molten pool. When the titanium component ratio is less than 0.5%, not enough crystal nuclei can be generated, and the effect of improving the toughness of the weld metal is not obvious. On the other hand, when the titanium component ratio exceeds 3%, the solid solution titanium will become too much, the strength of the weld metal will increase, and the low-temperature impact toughness will decrease. Therefore, the titanium component ratio should be controlled at 0.5-3%. In the present invention, titanium is mainly added in the form of titanium-iron alloy.

[0028] The arc stabilizer can mainly play the role of stabilizing arc combustion and reducing spatter during welding. It is usually added in the form of oxides with low electrical potential such as potassium and sodium. When it is less than 2%, the arc stabilization effect is not obvious. When it is greater than 6%, the melting point is low and the anti-moisture absorption effect is poor. Therefore, the proportion of the arc stabilizer should be controlled at 2-6%. In the present invention, the arc stabilizer is mainly added in the form of one or more of potassium titanate, high potassium feldspar, and potassium fluorosilicate.

[0029] The remaining part of the flux core is iron and unavoidable impurities. The iron in the welding flux comes from iron powder, ferrosilicon, ferromanganese, ferrosilicon manganese and other ferroalloy powders. The iron powder is added to increase the deposition speed and adjust the filling ratio of the flux-cored wire.

[0030] The present invention also provides a method for preparing the ultra-low hydrogen flux-cored welding wire, comprising the following steps:

[0031] (1) After weighing the raw materials of each component according to the proportion, mixing, sieving, drying and setting aside;

[0032] (2) After cleaning the steel strip, the steel strip is heated to 90-130° C. for drying, and then formed by U-groove rolling. During the wire drawing process, a lubricant including graphite, molybdenum disulfide, and low moisture absorption and non-hydrogenation containing no organic matter is used for drawing. The wire is drawn and reduced to a specified wire diameter to obtain a welding wire, and the residual wire drawing lubricant on the surface of the welding wire is cleaned, and finally a layer of nano coating is evenly coated on the surface of the welding wire;

[0033] (3) Winding the welding wire and raw materials into the ultra-low hydrogen flux-cored welding wire.

[0034] The lubricant used in the drawing and reducing process is a special lubricant. Different from ordinary lubricants, this lubricant does not contain organic matter and has excellent resistance to moisture absorption, which can effectively prevent hydrogen addition during welding.

[0035] The effects of the ultra-low hydrogen flux-cored welding wire and the preparation method thereof of the present invention are studied below through specific examples.

[0036] Embodiment 1:

[0037] The present embodiment provides an ultra-low hydrogen flux-cored welding wire, comprising an outer skin and a flux core filled in the outer skin, wherein the outer skin is a steel strip; in terms of mass percentage, the flux core comprises 40% TiO2, 1.5% sodium fluoride, 6% SiO2, 24% Mn, 6% Si, 3% Mg, 0.5% Ti, 6% potassium titanate, and the remainder is iron powder. The steel strip is a low-carbon, low-oil and low-impurity steel strip, and the proportion of each component in the steel strip is Mn 0.2%, Si 0.01%, C 0.01%, S 0.005%, and P ≤ 0.008%. S and P are harmful impurities in the deposited metal. Excessive content will lead to poor performance and prone to cracks, so they are as low as possible in the design, and the remainder is Fe. The flux core accounts for 13.3% of the total mass of the flux-cored welding wire.

[0038] The ultra-low hydrogen flux-cored welding wire is prepared by the following steps:

[0039] (1) After weighing the raw materials of each component according to the proportion, mixing, sieving, drying and setting aside;

[0040] (2) After cleaning the steel strip, the steel strip is heated to 90° C. for drying, and then formed by U-groove rolling. During the wire drawing process, a lubricant including graphite, molybdenum disulfide, and no organic matter is used for drawing. The wire is drawn and reduced to a specified wire diameter to obtain a welding wire, and the residual wire drawing lubricant on the surface of the welding wire is cleaned, and finally a layer of nano coating is evenly coated on the surface of the welding wire;

[0041] (3) Winding the welding wire and raw materials into the ultra-low hydrogen flux-cored welding wire.

[0042] The chemical composition, mechanical properties and diffusible hydrogen of the deposited metal of the ultra-low hydrogen flux-cored welding wire were tested according to standard requirements and conventional industry methods. The results are shown in Table 1-3.

[0043] Embodiment 2:

[0044] This embodiment provides an ultra-low hydrogen flux-cored welding wire, comprising an outer skin and a flux core filled in the outer skin, wherein the outer skin is a steel strip; in terms of mass percentage, the flux core comprises 48% TiO2, 4.5% lithium fluoride, 3% SiO2, 16% Mn, 2% Si, 6% Mg, 3% Ti, 2% potassium titanate, and the remainder is iron powder. The steel strip is a low-carbon, low-oil and low-impurity steel strip, and the proportion of each component in the steel strip is Mn 0.4%, Si 0.015%, C 0.02%, S 0.006%, P≤0.007%, and the remainder is Fe. The flux core accounts for 14.5% of the total mass of the flux-cored welding wire.

[0045] The ultra-low hydrogen flux-cored welding wire is prepared by the following steps:

[0046] (1) After weighing the raw materials of each component according to the proportion, mixing, sieving, drying and setting aside;

[0047] (2) After cleaning the steel strip, the steel strip is heated to 130° C. for drying, and then formed by U-groove rolling. During the wire drawing process, a lubricant including graphite, molybdenum disulfide, and no organic matter is used for drawing. The wire is drawn and reduced to a specified wire diameter to obtain a welding wire, and the residual wire drawing lubricant on the surface of the welding wire is cleaned, and finally a layer of nano coating is evenly coated on the surface of the welding wire;

[0048] (3) Winding the welding wire and raw materials into the ultra-low hydrogen flux-cored welding wire.

[0049] The chemical composition, mechanical properties and diffusible hydrogen of the deposited metal of the ultra-low hydrogen flux-cored welding wire were tested according to standard requirements and conventional industry methods. The results are shown in Table 1-3.

[0050] Embodiment 3:

[0051] This embodiment provides an ultra-low hydrogen flux-cored welding wire, comprising an outer skin and a flux core filled in the outer skin, wherein the outer skin is a steel strip; in terms of mass percentage, the flux core comprises 45% TiO2, 3% lithium fluoride, 5% SiO2, 20% Mn, 5% Si, 5% Mg, 2% Ti, 4% potassium feldspar, and the balance is iron powder. The steel strip is a low-carbon, low-oil and low-impurity steel strip, and the proportion of each component in the steel strip is Mn 0.3%, Si 0.016%, C 0.014%, S≤0.007%, P≤0.008%, and the balance is Fe. The flux core accounts for 14% of the total mass of the flux-cored welding wire.

[0052] The ultra-low hydrogen flux-cored welding wire is prepared by the following steps:

[0053] (1) After weighing the raw materials of each component according to the proportion, mixing, sieving, drying and setting aside;

[0054] (2) After cleaning the steel strip, the steel strip is heated to 90° C. for drying, and then formed by U-groove rolling. During the wire drawing process, a lubricant including graphite, molybdenum disulfide, and no organic matter is used for drawing. The wire is drawn and reduced to a specified wire diameter to obtain a welding wire, and the residual wire drawing lubricant on the surface of the welding wire is cleaned, and finally a layer of nano coating is evenly coated on the surface of the welding wire;

[0055] (3) Winding the welding wire and raw materials into the ultra-low hydrogen flux-cored welding wire.

[0056] The chemical composition, mechanical properties and diffusible hydrogen of the deposited metal of the ultra-low hydrogen flux-cored welding wire were tested according to standard requirements and conventional industry methods. The results are shown in Table 1-3.

[0057] Embodiment 4:

[0058] This embodiment provides an ultra-low hydrogen flux-cored welding wire, comprising an outer skin and a flux core filled in the outer skin, wherein the outer skin is a steel strip; in terms of mass percentage, the flux core comprises 43% TiO2, 2.5% potassium fluorosilicate, 4.5% SiO2, 21% Mn, 3.5% Si, 4.5% Mg, 2.2% Ti, 3.6% potassium titanate, and the remainder is iron powder. The steel strip is a low-carbon, low-oil and low-impurity steel strip, and the proportion of each component in the steel strip is Mn 0.31%, Si 0.015%, C 0.016%, S 0.006%, P≤0.003%, and the remainder is Fe. The flux core accounts for 13.8% of the total mass of the flux-cored welding wire.

[0059] The ultra-low hydrogen flux-cored welding wire is prepared by the following steps:

[0060] (1) After weighing the raw materials of each component according to the proportion, mixing, sieving, drying and setting aside;

[0061] (2) After cleaning the steel strip, the steel strip is heated to 90° C. for drying, and then formed by U-groove rolling. During the wire drawing process, a lubricant including graphite, molybdenum disulfide, and no organic matter is used for drawing. The wire is drawn and reduced to a specified wire diameter to obtain a welding wire, and the residual wire drawing lubricant on the surface of the welding wire is cleaned, and finally a layer of nano coating is evenly coated on the surface of the welding wire;

[0062] (3) Winding the welding wire and raw materials into the ultra-low hydrogen flux-cored welding wire.

[0063] The chemical composition, mechanical properties and diffusible hydrogen of the deposited metal of the ultra-low hydrogen flux-cored welding wire were tested according to standard requirements and conventional industry methods. The results are shown in Table 1-3.

[0064] Table 1 Chemical composition of deposited metal

[0065] C Mn Si S P Example 1 0.045 1.35 0.27 0.0048 0.013 Example 2 0.042 1.38 0.28 0.0051 0.011 Example 3 0.046 1.39 0.31 0.0052 0.013 Example 4 0.047 1.33 0.29 0.0046 0.015

[0066] Table 2 Mechanical properties of deposited metal

[0067]

[0068]

[0069] Table 3 Diffusible hydrogen content of deposited metal (mercury method)

[0070]

[0071] The ultra-low hydrogen flux-cored welding wire provided by the present invention is an ultra-low hydrogen high-toughness acidic flux-cored welding wire of fine-grained steel. It has excellent all-position welding performance, stable arc, no arc deviation, small spatter, easy slag removal, Akv≥100J under -20°C conditions, and the weld has good cold crack resistance. The diffused hydrogen mercury test result of the deposited metal [H] <4mL / 100g, meeting the index requirements of ultra-low hydrogen.

[0072] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. An ultra-low hydrogen flux-cored welding wire, comprising an outer sheath and a flux core filled in the outer sheath, characterized in that: The outer skin is a steel strip; in terms of mass percentage, the flux core includes 40-48% TiO2, 1.5-4.5% fluoride, 3-6% SiO2, 16-24% Mn, 2-6% Si, 3-6% Mg, 0.5-3% Ti, 2-6% arc stabilizer, and the balance is iron powder; The ultra-low hydrogen flux-cored welding wire is prepared by the following steps; (1) Weigh the raw materials of each component according to the ratio, mix them evenly, sieve them, dry them and set them aside; (2) cleaning and drying the steel strip, rolling and forming it, and then drawing and reducing it to a specified diameter to obtain a welding wire; drawing the wire with a lubricant, and removing the lubricant remaining on the surface of the welding wire after drawing; the lubricant includes graphite and molybdenum disulfide and does not contain organic matter; (3) Winding the welding wire and raw materials into the ultra-low hydrogen flux-cored welding wire.

2. The ultra-low hydrogen flux-cored welding wire according to claim 1, characterized in that: In terms of mass percentage, the steel strip contains 0.2-0.4% Mn, ≤0.02% Si, 0.01-0.02% C, ≤0.01% S, ≤0.01% P, and the balance is Fe.

3. The ultra-low hydrogen flux-cored welding wire according to claim 1, characterized in that: The flux core accounts for 13.3-14.5% of the total mass of the flux cored welding wire.

4. The ultra-low hydrogen flux-cored welding wire according to claim 1, characterized in that: In the step (2), the steel strip is heated to 90-130° C. for drying.

5. The ultra-low hydrogen flux-cored welding wire according to claim 1, characterized in that: After the drawing in step (2) is completed, the nano coating is evenly coated on the surface of the welding wire.

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