A composite steel core nickel-iron welding rod and its preparation method

Abstract

The present invention provides a composite steel-core nickel-iron welding rod and a preparation method thereof, specifically relating to the technical field of welding materials. The composite steel-core nickel-iron welding rod comprises a welding core, a steel strip, and a coating, wherein the steel strip is wrapped around the outside of the welding core, and the coating is coated on the outside of the steel strip. The coating comprises the following components, and the weight percentage of each component is respectively: 32-40 parts of marble, 18-23 parts of fluorite, 10-15 parts of barium carbonate, 5-10 parts of iron powder, 4-7 parts of graphite, 3-10 parts of nickel powder, 1-3 parts of metallic manganese, 3-5 parts of atomized ferrosilicon, 2-4 parts of feldspar, 0.5-1 part of soda ash, 0.3-0.5 parts of CMC, and 0.3-0.8 parts of microcrystalline cellulose; in terms of the mass percentage of the welding core, the welding core comprises the following components, and the content of each component is: nickel content ≥99wt%, and the balance is unavoidable impurities. The welding rod of the present application does not cause redness or heat, coating cracking, or shedding during welding, and can achieve ultra-high current and high-efficiency welding, reducing waste.

Description

Technical Field

[0001] The invention belongs to the technical field of welding materials, and particularly relates to a composite steel-cored nickel-iron welding rod and a preparation method thereof. Background Art

[0002] Nickel-iron welding rods, due to their high strength, low stress, adaptability, and all-position welding properties, are suitable for applications such as mechanical equipment, wear-resistant repair, and welding of special materials. For example, they are used in welding and repairing various cast iron and deformed materials, including carbon steel, low-alloy steel, and nickel alloys. Currently, commonly used nickel-iron welding rods suffer from coating cracking and shedding during welding, and the rear half of the rod becomes severely red and hot. Often, by the time the rod is halfway through welding, the rear half becomes so hot that it causes poor welding or is discarded, resulting in significant waste of resources and a serious impact on work efficiency. Summary of the Invention

[0003] In view of the above problems existing in the prior art, the present invention provides a composite steel core nickel-iron welding rod and a preparation method thereof to improve the problem that the coating of the existing nickel-iron welding rod is easy to crack and fall off, improve the utilization rate of the welding rod, and improve work efficiency.

[0004] To achieve the above-mentioned objectives and other related objectives, the present invention provides a composite steel-core nickel-iron welding rod in a first aspect, comprising a welding core, a steel strip and a coating, wherein the welding core is wrapped inside the steel strip and the coating is coated outside the steel strip, the coating comprising the following components and the weight percentage of each component is: 32-40 parts of marble, 18-23 parts of fluorite, 10-15 parts of barium carbonate, 5-10 parts of iron powder, 4-7 parts of graphite, 3-10 parts of nickel powder, 1-3 parts of metallic manganese, 3-5 parts of atomized ferrosilicon, 2-4 parts of feldspar, 0.5-1 part of soda ash, 0.3-0.5 parts of CMC, and 0.3-0.8 parts of microcrystalline cellulose; in terms of the mass percentage of the welding core, the welding core comprises the following components and the content of each component is: nickel content ≥99wt%, and the balance is unavoidable impurities.

[0005] In one example of the present invention, the steel strip is a low-carbon steel strip, and the steel strip includes the following components and the weight percentage of each component is: C≤0.05%, Mn≤0.35%, Si≤0.1%, S≤0.03%, P≤0.03%, and the rest is Fe and unavoidable impurities.

[0006] In an example of the present invention, the weight of the welding core is 45-55% of the total weight of the welding core and the steel strip.

[0007] In an example of the present invention, the weight of the welding core and the steel strip is 50-60% of the total mass of the composite steel-cored nickel-iron welding rod.

[0008] A second aspect of the present invention provides a method for preparing a composite steel-cored nickel-iron welding rod, comprising the following steps:

[0009] Cut the steel strip to the required width and roll it into a U shape using a rolling mill;

[0010] The welding core is placed inside the U-shaped steel strip, the U-shaped composite steel core with the welding core is joined into a circle, and the composite steel core is drawn to obtain the composite steel core;

[0011] The components of the coating are sieved and weighed separately to obtain coating powder;

[0012] Add the coating powder into a blender, add a binder into the blender, and stir and mix uniformly to obtain a coating mixed powder;

[0013] The coating mixed powder is press-coated on the composite steel core, and the composite steel core nickel-iron welding rod is obtained after drying.

[0014] In one example of the present invention, the binder is a water glass binder, and the added amount of the binder is 21-23% of the coating powder.

[0015] In an example of the present invention, the diameter of the composite steel core is 2.5-5.0 mm.

[0016] In one example of the present invention, marble, fluorite, nickel powder, iron powder, metallic manganese, atomized ferrosilicon, and feldspar are sieved through a 40-mesh sieve, microcrystalline cellulose is sieved through a 120-mesh sieve, and barium carbonate and soda ash are sieved through an 80-mesh sieve.

[0017] In an example of the present invention, the drying temperature is 280-300° C., and the drying time is 1-2 hours.

[0018] The composite steel-core nickel-iron welding rod of the present application wraps a steel strip around the outside of the welding core, which is then coated with a flux coating. The welding core is made of nickel metal, and the steel strip is made of low-carbon steel. Low-carbon steel has a low resistivity and minimal expansion. The welding rod does not become red or hot during welding, and the flux coating does not crack or fall off. This allows for efficient welding at ultra-high currents, reducing waste. Furthermore, the welding processability and mechanical properties of the welding rod of the present application are stable. Due to the improved conductivity of the welding rod, the welding rod combustion is more stable, the droplet transfer is more uniform and stable, and the weld performance is more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 FIG1 is a flow chart of the preparation of the composite steel-cored nickel-iron welding rod according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the 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 the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0022] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those in the examples of the present invention may also be used to implement the present invention.

[0023] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0024] It should be noted that "%" and "wt%" in this specification represent mass percentages, and "parts" represent parts by weight.

[0025] The invention provides a composite steel-core nickel-iron welding rod. The composite steel-core nickel-iron welding rod comprises a welding core, a steel strip and a coating, wherein the welding core is wrapped inside the steel strip and the coating is coated outside the steel strip. The welding core is characterized in that the coating comprises the following components, and the weight percentage of each component is respectively: 32-40 parts of marble, 18-23 parts of fluorite, 10-15 parts of barium carbonate, 5-10 parts of iron powder, 4-7 parts of graphite, 3-10 parts of nickel powder, 1-3 parts of metallic manganese, 3-5 parts of atomized ferrosilicon, 2-4 parts of feldspar, 0.5-1 part of soda ash, 0.3-0.5 part of CMC, and 0.3-0.8 part of microcrystalline cellulose. Calculated by mass percentage of the welding core, the welding core comprises the following components, and the content of each component is as follows: nickel content is ≥99wt%, and the balance is unavoidable impurities.

[0026] In one embodiment, the steel strip is a low-carbon steel strip, and the steel strip includes the following components and the weight percentage of each component is: C≤0.05%, Mn≤0.35%, Si≤0.1%, S≤0.03%, P≤0.03%, and the rest is Fe and unavoidable impurities.

[0027] In one embodiment, the weight of the welding core is 45-55% of the total weight of the welding core and the steel strip.

[0028] In one embodiment, the weight of the welding core and the steel strip is 50-60% of the total mass of the composite steel-cored nickel-iron welding rod.

[0029] In this application, the functions of the components in the coating are as follows:

[0030] Metallic manganese: Mainly used as a deoxidizer, alloying agent and desulfurizer, it transfers the Mn element to the weld to improve the weld strength.

[0031] Atomized ferrosilicon: Mainly used as a deoxidizer and alloying agent. Adding too much will increase spatter and reduce toughness, while adding too little will lead to poor molten pool fluidity and poor mechanical properties of the weld.

[0032] Nickel powder: Mainly used for alloying to adjust the nickel content of the electrode deposited metal, so that the weld has better crack resistance and corrosion resistance.

[0033] Graphite: Its primary function is to deoxidize and introduce carbon into the weld. Carbon helps reduce the formation of thermal cracks. The addition of carbon allows for more uniform volumetric contraction of the weld metal during cooling, reducing stress concentration and, consequently, shrinkage stress. Graphite also increases the slipperiness of the flux, improving the electrode's coating properties and surface smoothness.

[0034] Iron powder: Regulates the chemical composition of the deposited metal and stabilizes the electrode's performance. Iron powder also improves arc conditions and regulates the fluidity of molten iron.

[0035] Marble: Its primary component is CaCO3, which has both gas- and slag-forming properties. During welding, it decomposes to produce CO2 and CaO-based alkaline oxides, which protect the weld pool from air intrusion. CaO increases slag alkalinity, refines droplets, and removes sulfur and phosphorus, improving the weld metal's crack resistance. Excessive addition can increase spatter, while insufficient addition can result in porosity.

[0036] Fluorite: Its main component is CaF2. It has slag-forming, deoxidizing, and dehydrogenating properties, regulating slag viscosity and improving weld fluidity. Fluorite combines with the harmful element hydrogen, reducing hydrogen content and purifying the weld. Excessive addition can lead to poor weld formation, while insufficient addition can easily cause porosity defects.

[0037] Mica and feldspar: the main arc stabilizers. The low-ionized substances they contain, such as K, Na and other elements, can effectively increase the stability of the arc. If too much is added, the amount of smoke will increase, and if too little is added, the arc stabilization effect will not be obvious.

[0038] The composite steel-core nickel-iron welding rod of the present application does not have the problem of redness and heat during welding, and the coating does not have the problem of cracking or falling off. It can achieve ultra-large current and efficient welding, reduce waste, and has stable welding processability and mechanical properties. The welding rod combustion is more stable, the molten droplet transition is more uniform and stable, and the weld performance is more stable.

[0039] See also Figure 1 The present invention also provides a method for preparing a composite steel-cored nickel-iron welding rod, comprising the following steps:

[0040] S1, cutting the steel strip to the required width and rolling it into a U shape using a rolling mill;

[0041] S2. Place the welding core inside the U-shaped steel strip, sew the U-shaped composite steel core with the welding core into a circle, and draw it to obtain the composite steel core;

[0042] S3. Sieve and weigh the components of the coating separately to obtain coating powder;

[0043] S4, adding the coating powder into a blender, adding a binder into the blender, stirring and mixing evenly to obtain a coating mixed powder;

[0044] S5. Press-coat the coating mixed powder on the composite steel core, and dry it to obtain the composite steel core nickel-iron welding rod.

[0045] In step S1 , the steel strip is a low-carbon steel strip, and the steel strip includes the following components and the weight percentage of each component is: C≤0.05%, Mn≤0.35%, Si≤0.1%, S≤0.03%, P≤0.03%, and the rest is Fe and unavoidable impurities.

[0046] In step S2, the welding core comprises the following components and the content of each component is as follows: nickel content ≥ 99 wt%, with the remainder being unavoidable impurities. The diameter of the composite steel core is 2.5 to 5.0 mm, for example, any value within the range of 2.5 to 5.0 mm, such as 2.5 mm, 3.0 mm, 4.0 mm, or 5.0 mm.

[0047] In step S3, the coating includes the following components, with the weight percentages of each component being: 32-40 parts marble, 18-23 parts fluorite, 10-15 parts barium carbonate, 5-10 parts iron powder, 4-7 parts graphite, 3-10 parts nickel powder, 1-3 parts manganese metal, 3-5 parts atomized ferrosilicon, 2-4 parts feldspar, 0.5-1 part soda ash, 0.3-0.5 parts CMC, and 0.3-0.8 parts microcrystalline cellulose. In one embodiment, the marble, fluorite, nickel powder, iron powder, manganese metal, atomized ferrosilicon, and feldspar are passed through a 40-mesh sieve, the microcrystalline cellulose is passed through a 120-mesh sieve, and the barium carbonate and soda ash are passed through an 80-mesh sieve.

[0048] In step S4, the binder is a water glass binder, and the amount of the binder added is 21-23% of the coating powder, for example, any value within the range of 21%, 22% or 23%.

[0049] In step S5, the drying temperature is 280-300°C, for example, 280°C, 290°C, or 300°C, and the drying time is 1-2h, for example, 1h, 1.5h, or 2h, for example, any value within the range of 1-2h.

[0050] In the present application, the coating is stirred using a conventional stirring device and a conventional stirring method in the art, and the pressure coating uses a conventional pressure coating device and a conventional pressure coating method in the art, which will not be described in detail here.

[0051] The technical solutions of the present invention are described in detail below through several specific examples. Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by conventional methods in the art, and the instruments used in the examples are all commercially available.

[0052] In the following examples, marble, fluorite, nickel powder, iron powder, metallic manganese, atomized ferrosilicon, and feldspar were sieved through a 40-mesh sieve, microcrystalline cellulose was sieved through a 120-mesh sieve, and barium carbonate and soda ash were sieved through an 80-mesh sieve.

[0053] Example 1

[0054] The composite steel-cored nickel-iron welding rod of this embodiment comprises a welding core, a steel strip, and a coating. The welding core is wrapped inside the steel strip, and the coating is applied to the outside of the steel strip. The coating comprises the following components, by weight: 32 parts marble, 18 parts fluorite, 15 parts barium carbonate, 5 parts iron powder, 7 parts graphite, 10 parts nickel powder, 1 part metallic manganese, 3 parts atomized ferrosilicon, 2 parts feldspar, 0.5 parts soda ash, 0.3 parts CMC, and 0.5 parts microcrystalline cellulose. The nickel content of the welding core is 99.5 wt%.

[0055] In this embodiment, the preparation method of the composite steel core nickel-iron welding rod is as follows: cutting the steel strip to the required width and rolling it into a U shape using a rolling mill; placing the welding core inside the U-shaped steel strip, and sewing the U-shaped composite steel core with the welding core into a circle, and drawing to obtain the composite steel core; sieving the components of the coating separately and weighing them according to the above ratio to obtain coating powder; adding the coating powder to a blender, and adding a binder to the blender, stirring and mixing evenly to obtain a coating mixed powder; press-coating the coating mixed powder on the composite steel core, and drying it at 280°C for 2 hours to obtain a composite steel core nickel-iron welding rod.

[0056] In this embodiment, the weight of the welding core is 45% of the weight of the composite steel core, the weight of the composite steel core is 50% of the total weight of the welding rod, the added amount of the binder is 23% of the total weight of the coating powder, and the diameter of the composite steel core is 4.0 mm.

[0057] Example 2

[0058] The composite steel-cored nickel-iron welding rod of this embodiment comprises a welding core, a steel strip, and a coating. The welding core is wrapped inside the steel strip, and the coating is applied to the outside of the steel strip. The coating comprises the following components, by weight: 36 parts marble, 20 parts fluorite, 10 parts barium carbonate, 7 parts iron powder, 5 parts graphite, 7 parts nickel powder, 2 parts metallic manganese, 4 parts atomized ferrosilicon, 3 parts feldspar, 1 part soda ash, 0.5 parts CMC, and 0.8 parts microcrystalline cellulose. The nickel content of the welding core is 99 wt%.

[0059] In this embodiment, the preparation method of the composite steel core nickel-iron welding rod is as follows: cut the steel strip to the required width and roll it into a U shape using a rolling mill; place the welding core inside the U-shaped steel strip, and sew the U-shaped composite steel core with the welding core into a circle, and draw to obtain the composite steel core; sieve the components of the coating separately and weigh them according to the above ratio to obtain coating powder; add the coating powder to a blender, and add a binder to the blender, stir and mix evenly to obtain a coating mixed powder; press the coating mixed powder onto the composite steel core, and dry it at 300°C for 1 hour to obtain a composite steel core nickel-iron welding rod.

[0060] In this embodiment, the weight of the welding core is 50% of the weight of the composite steel core, the weight of the composite steel core is 60% of the total weight of the welding rod, the added amount of the binder is 22% of the total weight of the coating powder, and the diameter of the composite steel core is 3.2 mm.

[0061] Example 3

[0062] The composite steel-cored nickel-iron welding rod of this embodiment comprises a welding core, a steel strip, and a coating. The welding core is wrapped inside the steel strip, and the coating is applied to the outside of the steel strip. The coating comprises the following components, by weight: 40 parts marble, 22 parts fluorite, 11 parts barium carbonate, 10 parts iron powder, 4 parts graphite, 3 parts nickel powder, 3 parts metallic manganese, 5 parts atomized ferrosilicon, 4 parts feldspar, 0.8 parts soda ash, 0.4 parts CMC, and 0.6 parts microcrystalline cellulose. The nickel content of the welding core is 99.5 wt%.

[0063] In this embodiment, the preparation method of the composite steel core nickel-iron welding rod is as follows: cut the steel strip to the required width and roll it into a U shape using a rolling mill; place the welding core inside the U-shaped steel strip, and sew the U-shaped composite steel core with the welding core into a circle, and draw to obtain the composite steel core; sieve the components of the coating separately and weigh them according to the above ratio to obtain coating powder; add the coating powder to a blender, and add a binder to the blender, stir and mix evenly to obtain a coating mixed powder; press the coating mixed powder onto the composite steel core, and dry it at 290°C for 1 hour to obtain a composite steel core nickel-iron welding rod.

[0064] In this embodiment, the weight of the welding core is 55% of the weight of the composite steel core, the weight of the composite steel core is 53% of the total weight of the welding rod, the added amount of the binder is 21% of the total weight of the coating powder, and the diameter of the composite steel core is 2.5 mm.

[0065] Example 4

[0066] The composite steel-cored nickel-iron welding rod of this embodiment comprises a welding core, a steel strip, and a coating. The welding core is wrapped inside the steel strip, and the coating is applied to the outside of the steel strip. The coating comprises the following components, by weight: 38 parts marble, 23 parts fluorite, 12 parts barium carbonate, 8 parts iron powder, 6 parts graphite, 5 parts nickel powder, 1.5 parts metallic manganese, 3.5 parts atomized ferrosilicon, 2.5 parts feldspar, 0.6 parts soda ash, 0.3 parts CMC, and 0.3 parts microcrystalline cellulose. The nickel content of the welding core is 99.3% by weight.

[0067] In this embodiment, the preparation method of the composite steel core nickel-iron welding rod is as follows: cut the steel strip to the required width and roll it into a U shape using a rolling mill; place the welding core inside the U-shaped steel strip, and sew the U-shaped composite steel core with the welding core into a circle, and draw to obtain the composite steel core; sieve the components of the coating separately and weigh them according to the above ratio to obtain coating powder; add the coating powder to a blender, and add a binder to the blender, stir and mix evenly to obtain a coating mixed powder; press the coating mixed powder onto the composite steel core, and dry it at 285°C for 1.5 hours to obtain a composite steel core nickel-iron welding rod.

[0068] In this embodiment, the weight of the welding core is 47% of the weight of the composite steel core, the weight of the composite steel core is 57% of the total weight of the welding rod, the added amount of the binder is 21% of the total weight of the coating powder, and the diameter of the composite steel core is 5 mm.

[0069] Example 5

[0070] The composite steel-cored nickel-iron welding rod of this embodiment comprises a welding core, a steel strip, and a coating. The welding core is wrapped inside the steel strip, and the coating is applied to the outside of the steel strip. The coating comprises the following components, by weight: 32 parts marble, 18 parts fluorite, 15 parts barium carbonate, 5 parts iron powder, 7 parts graphite, 10 parts nickel powder, 1 part metallic manganese, 3 parts atomized ferrosilicon, 2 parts feldspar, 0.5 parts soda ash, 0.3 parts CMC, and 0.5 parts microcrystalline cellulose. The nickel content of the welding core is 99.3% by weight.

[0071] In this embodiment, the preparation method of the composite steel core nickel-iron welding rod is as follows: cut the steel strip to the required width and roll it into a U shape using a rolling mill; place the welding core inside the U-shaped steel strip, and sew the U-shaped composite steel core with the welding core into a circle, and draw to obtain the composite steel core; sieve the components of the coating separately and weigh them according to the above ratio to obtain coating powder; add the coating powder to a blender, and add a binder to the blender, stir and mix evenly to obtain a coating mixed powder; press the coating mixed powder onto the composite steel core, and dry it at 300°C for 1 hour to obtain a composite steel core nickel-iron welding rod.

[0072] In this embodiment, the weight of the welding core is 53% of the weight of the composite steel core, the weight of the composite steel core is 55% of the total weight of the welding rod, the added amount of the binder is 23% of the total weight of the coating powder, and the diameter of the composite steel core is 3.0 mm.

[0073] Comparative Example 1

[0074] The nickel-iron alloy welding rod of this comparative example includes a welding core and a coating coated on the surface of the nickel-iron alloy, wherein the welding core is made of nickel-iron alloy, and the nickel content of the nickel-iron alloy is 55wt% and the iron content is 45wt%, based on the mass percentage of the nickel-iron alloy; the coating includes the following components, and the weight percentage of each component is as follows: 32 parts of marble, 18 parts of fluorite, 15 parts of barium carbonate, 5 parts of iron powder, 7 parts of graphite, 10 parts of nickel powder, 1 part of metallic manganese, 3 parts of atomized ferrosilicon, 2 parts of feldspar, 0.5 part of soda ash, 0.3 part of CMC, and 0.5 part of microcrystalline cellulose.

[0075] The preparation method of the nickel-iron alloy welding rod in this comparative example is as follows: the components of the coating are sieved separately and weighed according to the above ratio to obtain a coating powder; the coating powder is added to a blender, and a binder is added to the blender, and stirred and mixed uniformly to obtain a coating mixed powder; the coating mixed powder is press-coated on the nickel-iron alloy, and dried at 300°C for 1 hour to obtain the nickel-iron alloy welding rod.

[0076] In this comparative example, the weight of the welding core is 55% of the weight of the nickel-iron alloy welding rod, the amount of the binder added is 23% of the total weight of the coating powder, and the diameter of the nickel-iron alloy is 4.0 mm.

[0077] Comparative Example 2

[0078] The difference between this comparative example and comparative example 1 is that the diameter of the nickel-iron alloy is 3.2 mm.

[0079] Comparative Example 3

[0080] The difference between this comparative example and comparative example 1 is that the diameter of the nickel-iron alloy is 2.5 mm.

[0081] Comparative Example 4

[0082] The difference between this comparative example and comparative example 1 is that the diameter of the nickel-iron alloy is 5.0 mm.

[0083] Welding tests were conducted on the welding rods prepared in Examples 1 to 5 and Comparative Examples 1 to 4. The welding process performance is shown in Table 1. In accordance with "Cast Iron Welding Rods and Wires (GB / T 10044-2006)", the chemical composition of the deposited metal was tested to compare the uniformity of the chemical composition of the deposited metal, and the tensile strength of the deposited metal was tested. The chemical composition of the deposited metal is shown in Table 2, and the mechanical properties of the deposited metal are shown in Table 3:

[0084] Table 1: Welding process performance of welding rods prepared in Examples 1 to 5 and Comparative Examples

[0085]

[0086] Note: The electrode utilization rate is the ratio of the length of the usable electrode to the total length of the electrode.

[0087] When the composite steel-core nickel-iron welding rod of the present invention is welded, the processability of the entire welding rod does not change significantly, the spatter is small, the arc is stable, and the welding rod has no obvious tail red phenomenon. When the nickel-iron alloy welding rod prepared in the comparative example is welded, the welding processability of the first half is good, and after the rear section of the welding rod emits red light, the spatter becomes larger, the arc is unstable, and the processability is poor.

[0088] Table 2: Chemical composition of deposited metal and tensile strength of deposited metal of welding rods prepared in Examples 1 to 5

[0089]

[0090] The composite steel core nickel-iron welding rod of the present application wraps a steel strip around the outside of the welding core and coats the outside of the steel strip with a coating. The welding core is made of metallic nickel and the steel strip is made of low-carbon steel. The resistivity of low-carbon steel is low and the expansion phenomenon is not obvious. The welding rod does not have the problem of redness and heating during welding, and the coating does not have the problem of cracking or falling off. It can achieve ultra-high current and efficient welding, reducing waste. At the same time, the welding processability and mechanical properties of the welding rod of the present application are stable. Due to the improved conductivity of the welding rod, the welding rod combustion is more stable, the molten droplet transition is more uniform and stable, and the weld performance is more stable. Therefore, the present invention effectively overcomes some practical problems in the prior art and has high utilization value and use significance.

[0091] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A composite steel-cored nickel-iron welding rod, characterized in that: The invention comprises a welding core, a steel strip and a coating, wherein the steel strip is wrapped around the outside of the welding core, and the coating is coated on the outside of the steel strip. The coating comprises the following components and the weight proportions of the components are as follows: 32-40 parts of marble, 18-23 parts of fluorite, 10-15 parts of barium carbonate, 5-10 parts of iron powder, 4-7 parts of graphite, 3-10 parts of nickel powder, 1-3 parts of metallic manganese, 3-5 parts of atomized ferrosilicon, 2-4 parts of feldspar, 0.5-1 part of soda ash, CMC 0.3~0.5 parts of nickel, 0.3~0.8 parts of microcrystalline cellulose; the welding core comprises the following components and the content of each component is as follows, calculated by mass percentage of the welding core: nickel content ≥99wt%, and the balance is inevitable impurities; the steel strip is a low-carbon steel strip, and the steel strip comprises the following components and the weight percentage of each component is: C≤0.05%, Mn≤0.35%, Si≤0.1%, S≤0.03%, P≤0.03%, and the rest is Fe and inevitable impurities.

2. The composite steel-cored nickel-iron welding rod according to claim 1, characterized in that: The weight of the welding core is 45-55% of the total weight of the welding core and the steel strip.

3. The composite steel-cored nickel-iron welding rod according to claim 1, characterized in that: The weight of the welding core and the steel strip is 50-60% of the total mass of the composite steel-core nickel-iron welding rod.

4. A method for preparing the composite steel-cored nickel-iron welding rod according to any one of claims 1 to 3, characterized in that: The following steps are involved: Cut the steel strip to the required width and roll it into a U shape using a rolling mill; The welding core is placed inside the U-shaped steel strip, the U-shaped composite steel core with the welding core is joined into a circle, and the composite steel core is drawn to obtain the composite steel core; The components of the coating are sieved and weighed separately to obtain coating powder; Add the coating powder into a blender, add a binder into the blender, and stir and mix uniformly to obtain a coating mixed powder; The coating mixed powder is press-coated on the composite steel core, and then dried to obtain a composite steel core nickel-iron welding rod.

5. The preparation method according to claim 4, characterized in that The binder is a water glass binder, and the added amount of the binder is 21-23% of the coating powder.

6. The preparation method according to claim 4, characterized in that The diameter of the composite steel core is 2.5-5.0 mm.

7. The preparation method according to claim 4, characterized in that Marble, fluorite, nickel powder, iron powder, metallic manganese, atomized ferrosilicon, and feldspar were sieved through a 40-mesh sieve, microcrystalline cellulose was sieved through a 120-mesh sieve, and barium carbonate and soda ash were sieved through an 80-mesh sieve.

8. The preparation method according to claim 4, characterized in that The drying temperature is 280~300℃ and the drying time is 1~2h.

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