A surfacing flux-cored wire and a method of making the same

Abstract

This invention discloses a flux-cored welding wire for surfacing and its preparation method. The flux-cored welding wire consists of an outer sheath and a flux core. The flux core is composed of the following components by mass percentage: chromium 10%-30%, hollow cage-like carbon microspheres 0.25%-1.0%, manganese fluoride 12.5%-14.8%, nickel 3.2%-5.5%, molybdenum 0.2%-0.8%, aluminum-magnesium alloy 3%-8%, aluminum-silicon alloy 1%-3%, rare earth elements 0.01%-0.1%, and the remainder being iron. By optimizing the component ratios, the above-mentioned flux-cored welding wire possesses advantages such as high hardness, excellent crack resistance, and high-temperature stability.

Description

Technical Field

[0001] This invention relates to the field of welding materials technology, and more particularly to a flux-cored welding wire suitable for surface repair and strengthening of equipment under high temperature and high wear conditions, and its preparation method. This welding wire is especially suitable for wear repair of equipment such as grinding rollers and extrusion rollers in industries such as cement, steel, and thermal power, and can significantly improve equipment service life and reduce production costs. Background Technology

[0002] Self-shielded flux-cored wire surfacing technology, as an important means of modern industrial equipment repair, has significant advantages in improving repair efficiency, optimizing production costs, and extending equipment life. With the increasing demands for equipment maintenance in industries such as cement, steel, and thermal power, surfacing repair technology has become the preferred solution for addressing wear problems in critical equipment. Using self-shielded flux-cored wire for surfacing repair can effectively improve repair efficiency, shorten production cycles, and reduce costs, resulting in significant social and economic benefits in extending the safe lifespan of machinery and parts. Currently, a mainstream solution to the aforementioned equipment wear problems is to use wear-resistant flux-cored wire for surfacing repair to extend equipment service life.

[0003] Currently, the commonly used flux-cored welding wires for overlay welding in industry mainly adopt high-chromium and high-carbon alloy systems. Although they have good wear resistance, they have the following problems: (1) The overlay layer is prone to cracking, especially under thermal cycling conditions. In environments with drastic temperature changes, crack propagation can lead to the overlay layer peeling off and failing; (2) The impact resistance is insufficient, and it is prone to peeling off under dynamic loads. The overlay layer of existing welding wires is prone to peeling off, which cannot meet the repair needs of equipment such as extrusion rollers that bear impact loads; (3) The welding process performance is unstable, with large spatter and poor forming, which increases the subsequent processing costs and affects the welding efficiency; (4) The high-temperature hardness retention rate is low, and the hardness drops significantly above 600℃, which cannot meet the requirements of high-temperature working conditions.

[0004] To address the aforementioned issues, there is an urgent need to develop a new type of flux-cored welding wire that combines high hardness, excellent crack resistance, and good high-temperature stability. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, one of the objectives of this invention is to provide a flux-cored welding wire for overlay welding. Through an innovative alloy system design, it solves the aforementioned problems of traditional technologies and is particularly suitable for surface repair and strengthening of equipment under high temperature and high wear conditions.

[0006] The second objective of this invention is to provide a method for preparing a flux-cored welding wire for overlay welding.

[0007] One of the objectives of this invention is achieved through the following technical solution:

[0008] A flux-cored welding wire for overlay welding consists of an outer sheath and a flux core, wherein the flux core is composed of the following components in mass percentage: 10%-30% chromium, 0.25%-1.0% hollow cage-like carbon microspheres, 12.5%-14.8% manganese fluoride, 3.2%-5.5% nickel, 0.2%-0.8% molybdenum, 3%-8% aluminum-magnesium alloy, 1%-3% aluminum-silicon alloy, 0.01%-0.1% rare earth elements, and the remainder being iron.

[0009] The design principle of this invention is as follows:

[0010] (1) Chromium: It can improve the hardness and wear resistance of the system through secondary hardening, and can also form a dense oxide film on the surface of the material, effectively resisting corrosion by oxidizing media. The chromium content should be controlled at 10%-30%.

[0011] (2) Hollow cage-like carbon microspheres: As a nano-reinforcing phase, they significantly improve the hardness and high-temperature stability of the weld overlay. The content of hollow cage-like carbon microspheres is controlled at 0.25%-1.0%.

[0012] (3) Manganese fluoride: significantly improves welding process performance, reduces spatter rate, and controls manganese fluoride content to 12.5%-14.8%;

[0013] (4) Nickel: can improve the corrosion resistance, plasticity and high temperature strength of the system, and the nickel content should be controlled at 3.2%-5.5%;

[0014] (5) Molybdenum: Improves high-temperature strength and creep resistance, enhances high-temperature service performance, and controls molybdenum content to 0.2%-0.8%;

[0015] (6) Aluminum-magnesium alloy: Improves the fluidity of the molten pool, ensures good weld formation, and controls the aluminum-magnesium alloy content to 3%-8%;

[0016] (7) Aluminum-silicon alloy: significantly refines the weld metal microstructure, improves strength while maintaining good plasticity and toughness, and controls the aluminum-silicon alloy content to 1%-3%;

[0017] (8) Rare earth: as a grain refiner and refining agent, it refines the alloy structure, improves the processing performance of welding wire, and controls the rare earth content to 0.01%-0.1%.

[0018] In summary, by optimizing the distribution ratio of each group, the welding wire can possess advantages such as high hardness, excellent crack resistance, and high-temperature stability.

[0019] Furthermore, the performance requirements for hollow cage-like carbon microspheres are: diameter 50-100 nm, specific surface area 200-400 m² / g. 2 / g, pore size distribution 2-10nm. Preferably, the hollow cage-like carbon microspheres are HCS-W50.

[0020] Furthermore, the mass ratio of aluminum to magnesium in the aluminum-magnesium alloy is (85-95):(5-15).

[0021] Furthermore, the mass ratio of aluminum to silicon in the aluminum-silicon alloy is (70-95):(5-30).

[0022] Furthermore, the rare earth elements are one or more of cerium, yttrium, lanthanum, neodymium, and gadolinium.

[0023] Furthermore, the filling rate of the core is 35wt%-50wt%.

[0024] Furthermore, the outer sheath is made of steel strip, preferably stainless steel 430 strip.

[0025] The second objective of this invention is achieved by the following technical solution:

[0026] A method for preparing a flux-cored welding wire for overlay welding includes the following preparation steps:

[0027] S1: Prepare the ingredients according to the proportions, pre-melt them using induction melting process, and obtain the ingot;

[0028] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder;

[0029] The above-mentioned core powder has a sphericity of over 80% and an oxygen content of less than 220 ppm.

[0030] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine. The forming machine rolls the outer sheath steel strip into a U-shaped groove. Then, add flux-cored powder into the U-shaped groove, controlling the filling rate of the flux-cored powder to be 35 wt%-50 wt%. Then, the forming machine rolls the U-shaped groove closed and draws it to a diameter of 2-6 mm to obtain the flux-cored wire.

[0031] Furthermore, in step S1, the pre-melting step using induction melting process is as follows: first, iron and manganese fluoride are melted under a protective atmosphere, and then the remaining materials are added in a secondary feeding manner. After complete melting and uniform stirring, the mixture is poured into an ingot.

[0032] In step S2, the specific steps are as follows: the temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, the nitrogen pressure is 2.9~3.3MPa, the nozzle adopts a tightly coupled confined ring structure, under the high-speed jet and cooling of nitrogen, the molten metal is dispersed into fine liquid mist and quickly solidified into powder, the powder falls into the collection bucket in the conical cylinder, and does not come into contact with air throughout the process.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. The flux-cored welding wire of the present invention optimizes the distribution ratio of each group, so that the welding wire has the advantages of high hardness, excellent crack resistance and high temperature stability.

[0035] 2. The specific advantages of the flux-cored welding wire of the present invention are as follows:

[0036] (1) Hollow cage-like carbon microspheres, as nano-reinforcing phases, significantly improve the hardness and high-temperature stability of the weld overlay;

[0037] (2) The aluminum-magnesium / silicon alloy combination optimizes the deoxidation of the molten pool and the grain boundary strengthening, thereby reducing crack sensitivity;

[0038] (3) Rare earth elements refine grains and improve the uniformity of carbide distribution;

[0039] (4) Manganese fluoride improves welding process performance and reduces spatter rate;

[0040] (5) Vacuum atomization powder making and precision drawing process are adopted to ensure the uniformity of the flux core composition and the accuracy of the welding wire size. Detailed Implementation

[0041] This invention provides a flux-cored welding wire for overlay welding and its preparation method, which overcomes the shortcomings of existing technologies through innovative alloy system design and precision preparation process.

[0042] 1. Technical Solution

[0043] This welding wire consists of an outer sheath and a flux core. The flux core adopts a multi-component composite strengthening system, with the following components by mass percentage:

[0044] Chromium (Cr): 10%-30%, forms hard carbides, providing basic hardness; for example: 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, etc.

[0045] Hollow cage-like carbon microspheres: 0.25%-1.0%, nano-reinforced phase, to improve high-temperature stability; for example: 0.25%, 0.28%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1.0%, etc.

[0046] Manganese fluoride (MnF2): 12.5%-14.8%, improves welding process performance; for example: 12.5%, 12.8%, 13%, 13.2%, 13.5%, 13.8%, 14%, 14.2%, 14.5%, 14.8%, etc.

[0047] Nickel (Ni): 3.2%-5.5%, improves corrosion resistance and high-temperature strength; for example: 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, etc.

[0048] Molybdenum (Mo): 0.2%-0.8%, enhancing creep resistance; 0.20%, 0.22%, 0.25%, 0.30%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, etc.

[0049] Aluminum-magnesium alloy: 3%-8%, improves the fluidity of the molten pool; for example: 3.0%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, etc.

[0050] Aluminum-silicon alloy: 1%-3%, refines weld microstructure; for example: 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, 2.2%, 2.5%, 2.8%, 3.0%, etc.

[0051] Rare earth elements: 0.01%-0.1%, grain refiner; for example: 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, etc.

[0052] Iron (Fe): Balance.

[0053] 2. Mechanism of action of each component

[0054] 2.1 Main Alloying Elements

[0055] (1) Chromium:

[0056] The hardness and wear resistance of the system are improved through secondary hardening.

[0057] A dense Cr2O3 oxide film is formed on the material surface to resist corrosion by oxidizing media;

[0058] It forms M7C3 type carbides with carbon, further increasing the hardness of the system;

[0059] The content should be controlled between 10% and 30%. If it is too low, the hardness will be insufficient, and if it is too high, the brittleness will increase.

[0060] (2) Hollow cage-like carbon microspheres:

[0061] Its unique hollow structure (50-100nm in diameter) can effectively hinder dislocation movement;

[0062] High specific surface area (200-400m²) 2 / g) Enhances the bonding strength with the matrix;

[0063] It remains stable at high temperatures, inhibiting carbide coarsening;

[0064] The preferred HCS-W50 model offers the best enhancement.

[0065] (3) Manganese fluoride:

[0066] Reduce the surface tension of the molten droplets and decrease splashing (splatter rate <1%);

[0067] As a deoxidizer, it reduces porosity defects;

[0068] It forms low-melting-point silicates with silicon, improving the fluidity of the slag system;

[0069] 2.2 Auxiliary Alloying Elements

[0070] (1) Nickel element:

[0071] Expanding the γ phase region improves plasticity and toughness;

[0072] An ordered Ni3Al phase is formed at high temperatures, enhancing high-temperature strength;

[0073] Improve corrosion resistance, especially in acidic environments;

[0074] (2) Molybdenum:

[0075] Solid solution reinforcement of the matrix improves high-temperature strength;

[0076] The formation of Mo2C carbides enhances creep resistance;

[0077] Inhibit σ phase precipitation and reduce embrittlement tendency;

[0078] (3) Aluminum-magnesium alloy:

[0079] Magnesium vapor creates a stirring effect, improving the fluidity of the molten pool;

[0080] Aluminum acts as a strong deoxidizer, reducing oxide inclusions;

[0081] The optimal Al:Mg mass ratio is (85-95):(5-15).

[0082] (4) Aluminum-silicon alloy:

[0083] Silicon promotes eutectic reactions and refines the solidification structure;

[0084] It forms fine, dispersed silicides, increasing strength;

[0085] The optimal Al:Si mass ratio is (70-95):(5-30).

[0086] (5) Rare earth elements:

[0087] Rare earth elements such as cerium (Ce) and yttrium (Y) purify grain boundaries;

[0088] Change the shape of inclusions to reduce stress concentration;

[0089] It promotes uniform distribution of carbides and inhibits the formation of network carbides.

[0090] In summary, by optimizing the distribution ratio of each group, the welding wire can possess advantages such as high hardness, excellent crack resistance, and high-temperature stability.

[0091] 3. Preparation process

[0092] The preparation method of the present invention includes the following key steps:

[0093] (1) Batching and pre-melting:

[0094] First, iron and manganese fluoride are smelted under a protective atmosphere. Then, the remaining materials are added in a two-stage feeding process. After complete melting and uniform stirring, the mixture is poured into an ingot.

[0095] In this step, a step-by-step feeding strategy is adopted: first, iron and manganese fluoride are melted, and then other components are added; melting is carried out under a protective atmosphere (nitrogen) to prevent element oxidation and loss; induction melting ensures the uniformity of composition.

[0096] (2) Vacuum atomization powder making:

[0097] Vacuum atomization powder making equipment is used to remelt ingots and produce core powder. The temperature of the molten metal is controlled at 900-1200℃, and high-purity nitrogen with a purity of 99.999% is used at a pressure of 2.9~3.3MPa. The nozzle adopts a tightly coupled confined annular structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in a conical cylinder without contacting air throughout the process.

[0098] In the above steps, the temperature of the molten metal is precisely controlled at 900-1200℃, 99.999% high-purity nitrogen is used, the pressure is 2.9-3.3Mpa, and a tightly coupled restrictive circular nozzle is used to ensure that the powder sphericity is >80%, and the entire process is oxygen-free with an oxygen content <220ppm.

[0099] (3) Welding wire forming:

[0100] The outer sheath is placed on the feeding machine of the flux-cored wire forming machine. The forming machine rolls the outer sheath steel strip into a U-shaped groove. Then, flux-cored powder is added into the U-shaped groove, and the filling rate of the flux-cored powder is controlled at 35 wt%-50 wt%. The forming machine then closes the U-shaped groove and draws it to a diameter of 2-6 mm to obtain the flux-cored wire.

[0101] In this step, the steel strip is rolled into a U-shaped groove with a filling rate of 35-50 wt%, and then precisely drawn to a diameter of 2-6 mm with a dimensional tolerance of ±0.05 mm. An online monitoring system ensures consistent quality.

[0102] The above steps employ vacuum atomization powder preparation and precision drawing processes to ensure the uniformity of the flux core composition and the dimensional accuracy of the welding wire.

[0103] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. In the following embodiments, the hollow cage-like carbon microspheres are HCS-W50, with a diameter of 50 nm and a specific surface area of ​​350 m². 2 / g, pore size distribution 5nm, steel strip is stainless steel 430 steel strip.

[0104] Example 1

[0105] A flux-cored welding wire for overlay welding consists of an outer sheath and a flux core, wherein the flux core is composed of the following components in mass percentage: 10% chromium, 0.5% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 2% aluminum-silicon alloy (Al:Si=80:20), 0.06% cerium, and the remainder is iron.

[0106] The preparation steps are as follows:

[0107] S1: Prepare the ingredients according to the proportion. First, melt iron and manganese fluoride under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour into an ingot.

[0108] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0109] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0110] Example 2

[0111] A flux-cored welding wire for overlay welding consists of an outer sheath and a flux core, wherein the flux core is composed of the following components in mass percentage: 20% chromium, 0.5% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 4.8% nickel, 0.6% molybdenum, 6% aluminum-magnesium alloy (Al:Mg=85:15), 2.5% aluminum-silicon alloy (Al:Si=85:15), 0.06% lanthanum, and the remainder is iron.

[0112] The preparation steps are as follows:

[0113] S1: Prepare the ingredients according to the proportion. First, melt iron and manganese fluoride under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour into an ingot.

[0114] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0115] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0116] Example 3

[0117] A flux-cored welding wire for overlay welding consists of an outer sheath and a flux core. The flux core is composed of the following components in weight percentage: 30% chromium, 0.5% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 5.2% nickel, 0.7% molybdenum, 7% aluminum-magnesium alloy (Al:Mg=85:15), 3% aluminum-silicon alloy (Al:Si=90:10), 0.04% cerium, 0.04% yttrium, and the remainder is iron.

[0118] The preparation steps are as follows:

[0119] S1: Prepare the ingredients according to the proportion. First, melt iron and manganese fluoride under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour into an ingot.

[0120] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0121] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0122] Example 4

[0123] A flux-cored welding wire for surfacing consists of an outer sheath and a flux core, wherein the flux core is composed of the following components in mass percentage: 25% chromium, 0.25% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 2% aluminum-silicon alloy (Al:Si=80:20), 0.06% cerium, and the remainder is iron.

[0124] The preparation steps are as follows:

[0125] S1: Prepare the ingredients according to the proportion. First, melt iron and manganese fluoride under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour into an ingot.

[0126] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0127] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0128] Example 5

[0129] A flux-cored welding wire for overlay welding consists of an outer sheath and a flux core, wherein the flux core is composed of the following components in mass percentage: 25% chromium, 0.5% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 2% aluminum-silicon alloy (Al:Si=80:20), 0.06% cerium, and the remainder is iron.

[0130] The preparation steps are as follows:

[0131] S1: Prepare the ingredients according to the proportion. First, melt iron and manganese fluoride under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour into an ingot.

[0132] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0133] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0134] Example 6

[0135] A flux-cored welding wire for overlay welding consists of an outer sheath and a flux core, wherein the flux core is composed of the following components in mass percentage: 25% chromium, 1.0% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 2% aluminum-silicon alloy (Al:Si=80:20), 0.06% cerium, and the remainder is iron.

[0136] The preparation steps are as follows:

[0137] S1: Prepare the ingredients according to the proportion. First, melt iron and manganese fluoride under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour into an ingot.

[0138] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0139] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0140] Comparative Example 1

[0141] Unlike Example 1, Comparative Example 1 does not contain hollow cage-like carbon microspheres; otherwise, it is the same as Example 1.

[0142] Specifically, the welding wire consists of an outer sheath and a core, the core of which is composed of the following components by mass percentage: 10% chromium, 13.5% manganese fluoride, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 2% aluminum-silicon alloy (Al:Si=80:20), 0.06% cerium, and the remainder is iron.

[0143] The preparation steps are as follows:

[0144] S1: Prepare the ingredients according to the proportion. First, melt iron and manganese fluoride under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour into an ingot.

[0145] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0146] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0147] Comparative Example 2

[0148] Unlike Example 1, Comparative Example 2 does not contain rare earth (cerium), but is otherwise the same as Example 1.

[0149] Specifically, the flux-cored welding wire consists of an outer sheath and a flux core. The flux core is composed of the following components by mass percentage: 10% chromium, 0.5% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 2% aluminum-silicon alloy (Al:Si=80:20), and the remainder is iron.

[0150] The preparation steps are as follows:

[0151] S1: Prepare the ingredients according to the proportion. First, melt iron and manganese fluoride under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour into an ingot.

[0152] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0153] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0154] Comparative Example 3

[0155] Unlike Example 1, Comparative Example 3 does not contain aluminum-silicon alloy, but is otherwise the same as Example 1.

[0156] The flux-cored welding wire consists of an outer sheath and a flux core, which is composed of the following components by mass percentage: 10% chromium, 0.5% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 0.06% cerium, and the remainder is iron.

[0157] The preparation steps are as follows:

[0158] S1: Prepare the ingredients according to the proportion. First, melt iron and manganese fluoride under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour into an ingot.

[0159] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0160] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0161] Comparative Example 4

[0162] Unlike Example 1, Comparative Example 4 does not contain manganese fluoride, but is otherwise the same as Example 1.

[0163] The flux-cored welding wire consists of an outer sheath and a flux core, which is composed of the following components by mass percentage: 10% chromium, 0.5% hollow cage-like carbon microspheres, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 2% aluminum-silicon alloy (Al:Si=80:20), 0.06% cerium, and the remainder is iron.

[0164] The preparation steps are as follows:

[0165] S1: Prepare the ingredients according to the proportion. First, melt the iron under a protective atmosphere of nitrogen. Then, add the remaining materials in a two-stage feeding method. After complete melting and stirring, pour the mixture into an ingot.

[0166] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0167] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0168] Comparative Example 5

[0169] Unlike Example 1, Comparative Example 5 is as follows:

[0170] A flux-cored welding wire for surfacing consists of an outer sheath and a flux core, wherein the flux core is composed of the following components in mass percentage: 50% chromium, 0.5% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 2% aluminum-silicon alloy (Al:Si=80:20), 0.06% cerium, and the remainder is iron.

[0171] The preparation steps are as follows:

[0172] S1: Prepare the ingredients according to the proportion, melt them completely and stir them evenly under a protective atmosphere of nitrogen, and then pour them into an ingot.

[0173] S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder. The temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, and the nitrogen pressure is 2.9~3.3MPa. The nozzle adopts a tightly coupled confined ring structure. Under the high-speed jet of nitrogen and cooling, the molten metal is dispersed into fine liquid mist and quickly solidifies into powder. The powder falls into the collection bucket in the conical cylinder without contacting the air throughout the process.

[0174] S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine, roll the outer sheath steel strip into a U-shaped groove through the forming machine, add flux-cored powder into the U-shaped groove, control the filling rate of the flux-cored powder to 40 wt%, then roll the U-shaped groove to close through the forming machine, and draw it to a diameter of 5mm to obtain the flux-cored wire.

[0175] Comparative Example 6

[0176] Unlike Example 1, Comparative Example 6 is as follows:

[0177] A flux-cored welding wire for overlay welding consists of an outer sheath and a flux core, wherein the flux core is composed of the following components in mass percentage: 2% chromium, 0.5% hollow cage-like carbon microspheres, 13.5% manganese fluoride, 4.5% nickel, 0.5% molybdenum, 5% aluminum-magnesium alloy (Al:Mg=90:10), 2% aluminum-silicon alloy (Al:Si=80:20), 0.06% cerium, and the remainder is iron.

[0178] The preparation steps are as follows:

[0179] Mix all materials thoroughly to obtain a mixed core powder;

[0180] The outer sheath is placed on the feeding machine of the flux-cored wire forming machine. The forming machine rolls the outer sheath steel strip into a U-shaped groove. Then, flux powder is added into the U-shaped groove, and the filling rate of the flux powder is controlled at 40 wt%. The forming machine then closes the U-shaped groove and draws it to a diameter of 5 mm to obtain the flux-cored wire.

[0181] Performance testing

[0182] 1. Hardness test

[0183] The surface hardness of the weld overlay was measured using a Rockwell hardness tester (HRC). The test standard is GB / T 230.1-2018. Five points were measured for each sample, and the average value was taken.

[0184] 2. High-temperature hardness test

[0185] The sample was heated to 600℃ and held for 1 hour. The hardness was measured using a special high-temperature hardness tester in a high-temperature environment. The hardness retention rate was calculated as (high-temperature hardness / room-temperature hardness) × 100%.

[0186] 3. Crack resistance test

[0187] The fishbone-shaped crack resistance test method was adopted. Welding was carried out along the center line of the specimen, and the crack propagation length was measured. The crack length ratio was rated as excellent (no macro cracks) if <15%, qualified if 15-30% (a few micro cracks) if , and unqualified if above 30%.

[0188] 4. Abrasion resistance test

[0189] The ML-100 abrasive wear tester was used with a load of 50 N and 80-mesh quartz sand as the abrasive. The wear resistance was expressed as the relative wear amount, compared with Example 1.

[0190] 5. Welding process testing

[0191] Using pulsed MIG welding technology, the ratio of spattered metal particles to the total amount of deposited metal during the welding process is defined by the following formula: Spatter rate = (mass of spatter / mass of molten core) × 100%.

[0192] 6. The test results are shown in Table 1 below.

[0193] Table 1

[0194]

[0195] As can be seen from the table above, compared with the comparative example, the welding wire of the present invention has the advantages of high hardness, excellent crack resistance and high temperature stability.

[0196] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A flux-cored welding wire for overlay welding, characterized in that, The product consists of an outer sheath and a core. The core is composed of the following components by mass percentage: chromium 10%-30%, hollow cage-like carbon microspheres 0.25%-1.0%, manganese fluoride 12.5%-14.8%, nickel 3.2%-5.5%, molybdenum 0.2%-0.8%, aluminum-magnesium alloy 3%-8%, aluminum-silicon alloy 1%-3%, rare earth elements 0.01%-0.1%, and the remainder being iron. The aluminum-magnesium alloy has an aluminum to magnesium mass ratio of (85-95):(5-15), and the aluminum-silicon alloy has an aluminum to silicon mass ratio of (70-95):(5-30). The hollow cage-like carbon microspheres have the following performance requirements: diameter 50-100 nm, specific surface area 200-400 m². 2 / g, pore size distribution 2-10nm, the hollow cage-like carbon microspheres are HCS-W50, the rare earth elements are one or more of cerium, yttrium, lanthanum, neodymium, and gadolinium; the outer skin is steel strip; the filling rate of the core is 35wt%-50wt%.

2. A method for preparing the flux-cored welding wire as described in claim 1, characterized in that, The preparation steps include the following: S1: Prepare the ingredients according to the proportions, pre-melt them using induction melting process, and obtain the ingot; S2: Vacuum atomization powder making equipment is used to remelt the ingot and make core powder; S3: Place the outer sheath on the feeding machine of the flux-cored wire forming machine. The forming machine rolls the outer sheath steel strip into a U-shaped groove. Then, add flux-cored powder into the U-shaped groove, controlling the filling rate of the flux-cored powder to be 35 wt%-50 wt%. Then, the forming machine rolls the U-shaped groove closed and draws it to a diameter of 2-6 mm to obtain the flux-cored wire.

3. The method for preparing the flux-cored welding wire for overlay welding according to claim 2, characterized in that, In step S1, the pre-melting step using induction melting process is as follows: first, iron and manganese fluoride are melted under a protective atmosphere, and then the remaining materials are added in a secondary feeding manner. After complete melting and uniform stirring, the mixture is poured into an ingot. In step S2, the specific steps are as follows: the temperature of the molten metal is controlled at 900-1200℃, high-purity nitrogen with a purity of 99.999% is used, the nitrogen pressure is 2.9~3.3MPa, and the nozzle adopts a tightly coupled confined ring structure.

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