Tubular electrode and method for its production and use

Abstract

The application provides a tubular electrode and a preparation method and application thereof, and relates to the technical field of wear-resistant surfacing. Specifically, the preparation method comprises the following steps: mixing metal powder and carbide particles, and then obtaining a tubular electrode with a seam through steel band rolling and drawing; placing the lap joint of the steel band of the tubular electrode with the seam downward, and performing high-temperature treatment to melt the metal powder; under the action of gravity, the molten metal liquid converges at the lap joint of the steel band, and after cooling, the self-sealing tubular electrode is obtained; wherein the melting point of the metal powder is lower than that of the carbide particles. The self-sealing tubular electrode can be mass-produced, and the metal-based sealing strip formed through sintering based on the action of gravity realizes similar leakage prevention, rust prevention and oxidation prevention functions as the seamless electrode, and simultaneously solves the difficulty of complex manufacturing process and difficulty in mass production of the seamless electrode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hardfacing, in particular to a tubular flux-cored electrode and a preparation method and application thereof. BACKGROUND

[0002] In the prior art, a tubular flux-cored electrode generally comprises an outer hollow tube and a core filler filled in the hollow cavity of the outer hollow tube. A high proportion (more than 60%) of carbide particles and a small amount of alloy elements (such as Ni, Co or their alloys) for improving the flow of the molten pool are usually added to the filler. The outer hollow tube is rolled from a cold-rolled low-carbon steel strip or a nickel alloy strip or a cobalt alloy strip. During the welding process, the outer hollow tube melts to form molten steel, which covers the high-melting-point carbide particles in the core filler and forms a wear-resistant layer on the base material, playing the roles of mechanical protection, metallurgical treatment and improvement of process performance.

[0003] However, the tubular flux-cored electrode often has the phenomenon of powder leakage during rolling. The filler powder leaks from the gaps of the loosely rolled hollow tube, resulting in loss of core material.

[0004] To solve this technical problem, there are solutions in the prior art, such as a method of drawing a seamless flux-cored electrode after filling a seamless hollow tube, a design method of reducing the powder leakage phenomenon by designing the structure of the hollow tube, and a method of welding the lap joint position to form a sealing structure by laser welding. However, the above improvement methods usually have high manufacturing costs, the weight coefficient of the flux powder is limited by the manufacturing method and cannot be improved, and the manufacturing scheme is not suitable for mass production.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The first object of the present application is to provide a preparation method of a tubular flux-cored electrode, which solves the problem of loss and waste caused by easy powder leakage of the tubular flux-cored electrode. The preparation method has the advantages of no limitation on the core flux powder, low cost, simple process and easy batch production.

[0007] The second object of the present application is to provide a tubular flux-cored electrode prepared based on the preparation method of the tubular flux-cored electrode.

[0008] The third object of the present application is to provide an application of the tubular flux-cored electrode in the field of hardfacing.

[0009] In order to achieve the above objects of the present application, the following technical solutions are adopted:

[0010] The application discloses a preparation method of a tubular electrode, and belongs to the technical field of welding materials.

[0011] The tubular electrode prepared by the preparation method of the tubular electrode.

[0012] The application of the tubular electrode in the field of wear-resistant surfacing, including but not limited to a wear-resistant surfacing method based on the tubular electrode, a metal welding piece welded based on the tubular electrode and the like.

[0013] Compared with the prior art, the tubular electrode has the following beneficial effects:

[0014] The self-sealing tubular tungsten carbide electrode can be mass-produced, and based on gravity, a nickel-based or cobalt-based sealing strip formed after sintering realizes similar leakage prevention, rust prevention and oxidation prevention functions as the seamless electrode in function, and meanwhile, the difficulties of a complicated manufacturing process and difficulty in mass production of the seamless electrode are solved. DETAILED DESCRIPTION

[0015] The technical solutions of the application will be described clearly and completely in combination with specific embodiments, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the application, rather than all the embodiments, and are only used to illustrate the application, and should not be regarded as limiting the scope of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application. The specific conditions are not indicated in the embodiments, and the conventional conditions or the conditions suggested by the manufacturer are used. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products that can be purchased in the market.

[0016] The application is implemented as follows: a preparation method of a tubular electrode, including the following steps: after mixing metal powder and carbide particles, a tubular electrode with a seam is obtained by steel strip rolling and drawing; the lap joint of the steel strip of the tubular electrode with the seam is placed downward, high-temperature treatment is performed, and then cooling is performed to obtain the tubular electrode; wherein the melting point of the metal powder is lower than that of the carbide particles.

[0017] The outer hollow tube of the tubular electrode of the present application adopts a steel coil, and the inner layer wear-resistant surfacing filler comprises high content of carbide particles and a small amount of specific metal powder; the tubular electrode is prepared through a conventional preparation method of the tubular electrode, and a tubular electrode with a seam is obtained, the lap joint gap of the tubular electrode with a seam is moved downward and subjected to high-temperature treatment, so that the metal powder is melted and in a molten state, the molten metal flows to the lap joint gap on the inner side of the steel strip through gravity and fills the lap joint gap, and the electrode is self-sealed after cooling; on the one hand, this process is simple, convenient and feasible, and the operation and equipment cost are low, which avoids the defect that it is difficult to produce on a large scale when laser is used to treat the lap joint position; on the other hand, the sealing gap formed after cooling has good uniformity and sealing effect, which avoids the phenomenon of powder leakage and achieves good oxidation prevention and protection effect.

[0018] As a preferred embodiment, the metal powder comprises at least one of nickel powder or cobalt powder; the melting point of the two kinds of metal powder is much lower than that of the carbide particles, and the molten liquid has good flow performance, which is easy to realize uniform distribution and filling in the lap joint gap of the steel strip; specifically, the nickel powder has good fluidity and spreading property, and is often used as a filler metal in the welding process of carbide to increase the fluidity of the molten pool; the cobalt powder also has good fluidity and spreading property, and has good ductility, but the cost of the cobalt powder is slightly higher than that of the nickel powder.

[0019] As a preferred embodiment, the carbide particles comprise at least one of tungsten carbide, vanadium carbide, titanium carbide, niobium carbide, etc.

[0020] As a preferred embodiment, the particle size of the metal powder is 150-400 mesh, and the particle size of the carbide particles is 60-80 mesh; as an optional embodiment, the particle size of the metal powder includes but is not limited to 150, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400 (unit: mesh), and the particle size of the carbide particles includes but is not limited to 60, 65, 70, 75, 80 (unit: mesh).

[0021] As a preferred embodiment, the mass ratio of the metal powder to the carbide particles is (3-8):(92-97); as an optional embodiment, the mass ratio of the metal powder to the carbide particles includes but is not limited to 3:97, 4:96, 5:95, 6:94, 7:93, 8:92; when the mass ratio of the metal powder to the carbide particles is too high, the excessive metal melt is prone to flow over during high-temperature treatment, affecting the quality of the steel strip sheath and reducing the weight coefficient of the flux-cored wire; when the mass ratio of the metal powder to the carbide particles is too low, the amount of the metal melt may be insufficient during high-temperature treatment, failing to achieve complete sealing and filling; thus, it is necessary to appropriately control the mass ratio of the metal powder to the carbide particles.

[0022] As a preferred embodiment, the total mass of the powder to the mass of the tubular flux-cored wire is 65%-80%; as an optional embodiment, the total mass of the powder to the mass of the tubular flux-cored wire includes but is not limited to 65%, 70%, 71%, 72%, 73%, 74%, 75%, 80%; that is, the mass ratio of the steel strip sheath to the tubular flux-cored wire is 20%-35%, and a series of weight ratios are used to achieve the filling of the metal powder melt into the gap of the steel strip; as a more preferred embodiment, the total mass of the powder to the mass of the tubular flux-cored wire is 70%-75%.

[0023] As a preferred embodiment, the temperature of the high-temperature treatment includes but is not limited to 1150, 1200, 1250, 1300, 1350, 1400, 1450 (unit: ℃), and the time of the high-temperature treatment includes but is not limited to 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4 (unit: h); under the above high-temperature treatment conditions, the morphology of the steel sheath and the carbide particles is relatively fixed, providing good external conditions for the melting and uniform filling of the metal powder.

[0024] As a preferred embodiment, the high-temperature treatment is performed under vacuum conditions; to avoid the influence of high-temperature oxidation on the metal powder or to avoid the ineffective filling of oxidized metal.

[0025] As a preferred embodiment, the diameter of the tubular flux-cored electrode includes but is not limited to 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0 (unit: mm), the length of the tubular flux-cored electrode includes but is not limited to 0.75, 1.0, 1.5, 2.0, 2.5, 3.0 (unit: m), the overlap width of the steel strip is 7.5 mm to 14.5 mm, including but not limited to 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 14.0, 14.5 (unit: mm).

[0026] Example 1

[0027] The core filler of the flux-cored electrode in this embodiment is composed of the following substances in mass ratio: tungsten carbide (60 mesh) 95%, nickel powder (60 mesh) 5%.

[0028] The preparation method of this embodiment is as follows: after the two raw materials are uniformly mixed, they are drawn into a steel strip by rolling, and then cut to 1 m long. The percentage of carbide and nickel powder in the total weight of the tubular flux-cored electrode is 72%. The outer skin of the tubular electrode is placed downward in the sintering furnace to heat to 1300℃, and after 1 hour of heat preservation, it is cooled with the furnace to form a sealed tubular tungsten carbide electrode from this embodiment.

[0029] Example 2

[0030] Basically the same as Example 1, the only difference is that the nickel powder is replaced by cobalt powder.

[0031] Example 3

[0032] Basically the same as Example 1, the only difference is that the nickel powder is replaced by a mixed powder of nickel powder and cobalt powder (mass ratio of nickel powder to cobalt powder is 1:1).

[0033] Example 4

[0034] Basically the same as Example 1, the only difference is that the tungsten carbide is replaced by titanium carbide.

[0035] Example 5

[0036] Basically the same as Example 1, the only difference is that the tungsten carbide is replaced by a mixed powder of carbide and titanium carbide (mass ratio of carbide to titanium carbide is 1:1).

[0037] Example 6

[0038] Basically the same as Example 1, the only difference is that the particle size of the tungsten carbide is 80 mesh and the particle size of the nickel powder is 100 mesh.

[0039] Example 7

[0040] The embodiment 1 is basically the same, except that the mass percentage of tungsten carbide in the core powder is 92%, and the mass percentage of nickel powder is 8%.

[0041] Embodiment 8

[0042] The embodiment 1 is basically the same, except that the mass percentage of tungsten carbide in the core powder is 97%, and the mass percentage of nickel powder is 3%.

[0043] Embodiment 9

[0044] The embodiment 1 is basically the same, except that the heating temperature is 1150℃, and the holding time is 4 hours.

[0045] Embodiment 10

[0046] The embodiment 1 is basically the same, except that the heating temperature is 1450℃, and the holding time is 0.5 hours.

[0047] The sealed tubular welding rods prepared in the above embodiments are packaged, boxed and transported, and a conventional commercial tubular tungsten carbide welding rod with a seam is used as a comparison. It is found that the powder leakage rate of the welding rod prepared in the embodiments is reduced by 99.8% compared with the conventional commercial welding rod, which is convenient for transportation and storage. The production efficiency of the welding rod in the embodiments is greatly improved, and the particles of the carbide are formed by high-temperature molten metal powder to reduce the stratification phenomenon caused by the large density difference between the metal powder and the carbide particles during transportation, thereby improving the uniformity of the core powder. In addition, the chemical analysis of the powder at the head and tail of the welding rod prepared in the embodiment 1 shows that the mass fraction deviation of Ni is reduced by more than 50% compared with the tubular cored welding rod or the seamless cored welding rod.

[0048] Although the present application has been illustrated and described with reference to specific embodiments, it should be recognized that the above embodiments are merely used to illustrate the technical solutions of the present application, and are not intended to limit the present application; it should be understood by those skilled in the art that the technical solutions described in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents without departing from the spirit and scope of the present application; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application; therefore, this means that all these replacements and modifications within the scope of the present application are included in the appended claims.

Claims

1. A method of making a tubular electrode, characterized by, The method comprises the following steps: mixing metal powder and carbide particles, and then rolling and drawing a steel strip to obtain a tubular flux-cored electrode with a seam; placing the lap joint of the steel strip of the tubular flux-cored electrode with a seam downward, and then performing high-temperature treatment and cooling to obtain the tubular flux-cored electrode. The melting point of the metal powder is lower than that of the carbide particles. The metal powder comprises at least one of nickel powder or cobalt powder, and the carbide particles comprise at least one of tungsten carbide, vanadium carbide, titanium carbide or niobium carbide; the mass ratio of the metal powder to the carbide particles is (3-8):(92-97). The temperature of the high-temperature treatment is 1150-1450℃.

2. The method of making a tubular electrode of claim 1, wherein, The particle size of the metal powder is 150-400 mesh, and the particle size of the carbide particles is 60-80 mesh.

3. The method of making a tubular electrode of claim 1 wherein, The total mass of the metal powder and the carbide particles is the total mass of the flux powder, and the mass ratio of the total mass of the flux powder to the tubular flux-cored electrode is 65%-80%.

4. The method of making a tubular electrode as defined in claim 3, wherein The mass ratio of the total mass of the flux powder to the tubular flux-cored electrode is 70%-75%.

5. The method of making a tubular electrode of claim 1 wherein, The time of the high-temperature treatment is 0.5-4h.

6. The method of making a tubular electrode of claim 1 wherein, The high-temperature treatment is performed under vacuum.

7. The method of making a tubular electrode of claim 1 wherein, The diameter of the tubular flux-cored electrode is 2.0-4.0mm, and the length of the tubular flux-cored electrode is 0.75-3m.

8. The tubular flux-cored electrode prepared by the method of any one of claims 1-7.

9. The tubular flux-cored electrode of claim 8 in the field of wear-resistant surfacing.