A surfacing flux-cored welding wire and its preparation method and welding method

Abstract

The present invention provides a surfacing flux-cored welding wire and a preparation method and a welding method thereof, and specifically relates to the field of welding materials. The surfacing flux-cored welding wire of the present invention comprises a steel strip and a flux core filled in the steel strip, and the flux core comprises the following components by mass percentage: 40-55% of medium carbon ferrochrome, 9-17% of metallic chromium, 3-5% of metallic manganese, 5-8% of ferrosilicon, 2-3% of nickel powder, and the balance is iron powder. The surfacing flux-cored welding wire of the present invention has excellent wear resistance, and the deposited metal has high hardness, strength and toughness, can effectively control the generation of cracks in the deposited metal of the surfacing layer, prevent it from falling off, and is suitable for repairing cold rolling rollers.

Description

Technical Field

[0001] The invention relates to the field of welding materials, and in particular to a surfacing flux-cored welding wire and a preparation method and a welding method thereof. Background Art

[0002] Cold rolling rolls are key components of cold rolling mills. Due to the extremely harsh working environment of cold rolling rolls, they have strict performance requirements for the working surface. Under huge variable pressure, their surface is required to have ultra-high hardness, good toughness and wear resistance. The repair of cold rolling rolls mainly adopts surfacing repair, but since most cold rolling rolls are cast with a high-chromium cast iron alloy system, the content of carbon and alloy elements in the high-chromium cast iron alloy system is very high, so the surfacing layer is very easy to crack when surfacing this type of roll. Therefore, the surfacing repair of cold rolling rolls requires high hardness and good hardness uniformity of the surfacing metal, and requires high crack resistance, good toughness and strong fatigue resistance. High-hardness surfacing materials at home and abroad are mainly high-chromium cast iron alloy systems, which are expensive; the repair of many parts in the domestic market is mainly completed by wear-resistant welding rods, which is time-consuming and laborious, and the repair period is long. In addition, the repair quality of wear-resistant welding rods is not as good as that of welding wires, so many repair processes cannot be realized or are difficult to realize.

[0003] At present, the international surfacing flux-cored wire industry has developed to a certain scale and has embarked on various series of industrial roads corresponding to the performance of surfacing electrodes. Among the flux-cored wires currently consumed in China, most of the wear-resistant surfacing flux-cored wires are imported products. There are fewer domestic wear-resistant surfacing flux-cored wires and the variety is single, which is far from meeting the market requirements. The price of imported welding wires from abroad is high and the ordering cycle is long. The research and development of cold-rolled roller surfacing flux-cored wires has broad market prospects and is of great significance. Summary of the invention

[0004] In view of the above shortcomings of the prior art, the present invention provides a cladding flux-cored welding wire and a preparation method and a welding method thereof, so as to improve the welding processability of the welding wire, the mechanical properties and corrosion resistance of the weld metal.

[0005] To achieve the above-mentioned purpose and other related purposes, the present invention provides a surfacing flux-cored welding wire, comprising a steel strip and a flux core filled in the steel strip, wherein the flux core comprises the following components, measured by mass percentage, of medium carbon ferrochrome 40-55%, metallic chromium 9-17%, metallic manganese 3-5%, ferrosilicon 5-8%, nickel powder 2-3%, and the balance is iron powder.

[0006] In an example of the present invention, the carbon content in the medium carbon ferrochrome is 1-1.5wt%, and the chromium content is 78-85wt%.

[0007] In an example of the present invention, the ferrosilicon is 75# ferrosilicon, and the silicon content in the ferrosilicon is 72-75wt%.

[0008] In an example of the present invention, the steel strip is a HS1 steel strip, the width of the steel strip is 14 mm to 18 mm, and the thickness of the steel strip is 0.3 mm to 0.6 mm.

[0009] In an example of the present invention, the weight of the flux core in the cladding flux-cored welding wire is 20-30% of the total weight of the cladding flux-cored welding wire.

[0010] The present invention provides a method for preparing a cladding flux-cored welding wire, which is characterized in that it comprises the following steps: uniformly mixing the above components to configure a flux core; longitudinally shearing, wrapping, cleaning, and then rolling a steel strip into a U-shaped groove; filling the flux core into the U-shaped groove; closing, reducing the diameter, drawing, and winding the steel strip filled with the flux core to obtain the cladding flux-cored welding wire.

[0011] The invention provides a welding method for surfacing flux-cored welding wire, comprising the following steps: preheating a workpiece; performing base welding on the workpiece using a base welding wire; unilaterally surfacing welding the workpiece after base welding under a flux layer, tempering and cooling; repeating the above surfacing operation, and after the surfacing is completed, tempering the whole workpiece; cooling and taking out of the furnace.

[0012] In an example of the present invention, the preheating temperature when preheating the workpiece is 250-300°C.

[0013] In an example of the present invention, the thickness of the base layer during the base welding is less than 4 mm.

[0014] In one example of the present invention, the welding current during the surfacing welding is 450-550A, the welding voltage is 28-32V, and the workpiece temperature during the welding process is 200-250°C; the tempering temperature during the tempering is 480-510°C, and the holding time is 8-12h.

[0015] The cladding flux-cored welding wire of the present invention transitions alloy elements such as chromium, manganese, silicon, and nickel to the deposited metal. By adjusting the proportion of the alloy elements, the hardness and strength of the deposited metal can be improved. The cladding flux-cored welding wire has good wear resistance and certain toughness. The generation of cracks in the cladding layer deposited metal can be effectively controlled to prevent falling off. The cladding layer deposited metal is suitable for repairing cold rolling rolls in the steel industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 The present invention is a flow chart of the preparation of the cladding flux-cored welding wire;

[0018] Figure 2 The figure is a welding flow chart of the cladding flux-cored welding wire of the present invention. DETAILED DESCRIPTION

[0019] The following is an explanation of the embodiments of the present invention by specific examples, and 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 in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the features in the following embodiments and the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturers.

[0020] It should be noted that "%" and "wt%" in this specification represent mass percentage, and "part" represents part by weight.

[0021] The invention provides a surfacing flux-cored welding wire, comprising a steel strip and a flux core filled in the steel strip, wherein the flux core comprises the following components in percentage by mass: 40-55% of medium carbon ferrochrome, 9-17% of metallic chromium, 3-5% of metallic manganese, 5-8% of ferrosilicon, 2-3% of nickel powder, and the remainder is iron powder.

[0022] The functions of the components in the flux core of cladding flux-cored wire are as follows:

[0023] Medium carbon ferrochrome: alloy element for transition to the cladding layer; ferrochrome has strong oxidizability and can release heat to accelerate the reaction. In the cladding flux core of the present invention, the mass percentage of medium carbon ferrochrome is 40-55%, for example, the mass percentage of medium carbon ferrochrome can be any value within the range of 40-55%, such as 40%, 45% or 55%.

[0024] Metallic chromium: an alloying element that transitions to the cladding layer, increases the hardenability of the deposited metal and has a secondary hardening effect, which can improve the hardness and wear resistance of the deposited metal without making the deposited metal brittle; increasing the content of metallic chromium can improve the corrosion resistance of the deposited metal to oxidizing media; but excessive addition of metallic chromium will reduce the hardness and strength of the deposited metal. In the cladding flux core of the present invention, the mass percentage of metallic chromium is 9-17%, for example, the mass percentage of medium carbon ferrochrome can be any value within the range of 9-17%, such as 9%, 13% or 17%.

[0025] Metallic manganese: an alloying element that transitions to the cladding layer metal, deoxidizes and desulfurizes, forms a protective atmosphere, releases heat and accelerates the welding reaction speed. Manganese can improve the strength and hardness of the deposited metal, but when the amount of metallic manganese added is too much, the ductility, toughness and weldability of the deposited metal deteriorate. In the cladding flux core of the present invention, the mass percentage of metallic manganese is 3-5%, for example, the mass percentage of metallic manganese can be any value within the range of 3-5%, such as 3%, 4% or 5%.

[0026] Ferrosilicon: alloy element for transition to the cladding metal, deoxidation. Heat is released during welding, which accelerates the melting of welding wire, improves the fluidity of slag, reduces the porosity sensitivity of the cladding layer, makes the welding wave fine, and improves the hardness and strength of the deposited metal. However, excessive addition of ferrosilicon will reduce the toughness of the deposited metal. In the cladding flux core of the present invention, the mass percentage of ferrosilicon is 5-8%, for example, the mass percentage of ferrosilicon can be any value within the range of 5-8%, such as 5%, 7% or 8%.

[0027] Nickel powder: transition alloy element to the cladding layer to improve the toughness of the cladding layer. In the cladding flux core of the present invention, the mass percentage of nickel powder is 2-3%, for example, the mass percentage of nickel powder can be any value within the range of 2-3%, such as 2%, 2.5% or 3%.

[0028] Iron powder: supplement the insufficient alloy powder in the flux core and improve welding efficiency.

[0029] In one embodiment, the carbon content of the medium carbon ferrochrome is 1-1.5 wt %, the chromium content is 78-85 wt %, and the particle size of the medium carbon ferrochrome is preferably 60 mesh.

[0030] In one embodiment, the ferrosilicon is 75# ferrosilicon, the silicon content in the ferrosilicon is 72-75wt%, and the particle size of the ferrosilicon is preferably 60 mesh.

[0031] In one embodiment, the steel strip is an HS1 steel strip, the width of the steel strip is 14 mm to 18 mm, and the thickness of the steel strip is 0.3 mm to 0.6 mm. For example, the width of the steel strip can be any value within the range of 14 to 18 mm, such as 14 mm, 16 mm or 18 mm; the thickness of the steel strip can be any value within the range of 0.3 to 0.6 mm, such as 0.3 mm, 0.5 mm or 0.6 mm.

[0032] See also Figure 1 The present invention provides a method for preparing a cladding flux-cored welding wire, comprising the following steps:

[0033] S11, mixing the above components evenly to prepare a drug core;

[0034] S12, slitting, wrapping, cleaning and rolling the steel strip into a U-shaped groove;

[0035] S13, filling the drug core into the U-shaped groove;

[0036] S14, closing, reducing the diameter, drawing and winding the steel strip filled with the flux core to obtain the cladding core welding wire.

[0037] In step S11, the components in the core are mixed and stirred evenly according to the following ratios: 40-55% medium carbon ferrochrome, 9-17% metallic chromium, 3-5% metallic manganese, 5-8% ferrosilicon, 2-3% nickel powder, and the remainder iron powder.

[0038] In step S12, the steel strip is longitudinally cut into a suitable size and then cleaned to remove impurities on the surface of the steel strip, and then the steel strip is rolled into a U-shaped groove. The steel strip used in the present invention is HS1 steel strip, and the carbon content of the steel strip is 0.03wt%, the silicon content is 0.03wt%, the manganese content is 0.1-0.3wt%, the phosphorus content is 0.02wt%, and the sulfur content is 0.02wt%.

[0039] In step S13, the filling rate of the flux core, that is, the weight of the flux core in the cladding flux-cored welding wire is 20-30% of the total weight of the cladding flux-cored welding wire. For example, the filling rate of the flux core can be any value within the range of 20-30%, such as 20%, 25% or 30%.

[0040] In step S14, lubricating powder can be used to increase the lubricity of the wire drawing process. The diameter of the surfacing flux-cored wire is preferably 2.4 mm.

[0041] See also Figure 2 The present invention provides a welding method for surfacing flux-cored welding wire, comprising the following steps:

[0042] S21, preheating the workpiece;

[0043] S22, performing base welding on the workpiece using a base welding wire;

[0044] S23, perform single-side surfacing welding on the workpiece after base welding under the flux layer, temper and cool down;

[0045] S24, repeat the above surfacing operation, and after all surfacing operations are completed, perform overall tempering;

[0046] S25, cool down and take out of the oven.

[0047] In one embodiment, the thickness of the root weld is less than 4 mm.

[0048] In step S21, the preheating temperature when preheating the workpiece is 250-300°C. For example, the preheating temperature can be any value within the range of 250-300°C, such as 250°C, 280°C or 300°C.

[0049] In step S22, the thickness of the base layer during base welding is less than 4 mm; the base welding wire used during base welding can be selected conventionally in the art, which will not be described in detail here.

[0050] In step S23, tempering is performed when the single-side cladding thickness is about 30 mm to eliminate welding stress.

[0051] In step S24, after the workpieces are welded according to the welding requirements, tempering is performed to eliminate welding stress.

[0052] In steps S23 and S24, the welding current is 450-550A during surfacing welding, the welding voltage is 28-32V, the workpiece temperature is maintained at 200-250°C during welding, the tempering temperature is 480-510°C during tempering, and the holding time is 8-12h. For example, the temperature of the workpiece can be any value within the range of 200-250°C, such as 200°C, 220°C or 250°C; the welding current can be any value within the range of 450-550A, such as 450A, 500A or 550A; the welding voltage can be any value within the range of 28-32V, such as 28V, 30V or 32V; the tempering temperature can be any value within the range of 480-510°C, such as 480°C, 490°C or 510°C; the holding time can be any value within the range of 8-12h, such as 8h, 10h or 12h.

[0053] In step S25, after overall tempering, the workpiece is cooled to below 50°C in the furnace and the workpiece is taken out.

[0054] It should be noted that the parameters not described in detail in the above welding process can be set according to conventional welding processes in the art.

[0055] The present invention is described in detail below through some specific examples. The drugs used in the following examples can all be obtained through common commercial means.

[0056] Example 1

[0057] The cladding flux-cored welding wire of this embodiment includes a steel strip and a flux core filled in the steel strip, wherein the flux core includes the following components by mass percentage: 55% medium carbon ferrochrome, 10% metallic chromium, 5% metallic manganese, 6% ferrosilicon, 2% nickel powder, and the balance is iron powder. The steel strip is selected from HS1 steel strip, the steel strip is rolled into a U-shaped groove, and then the mixed flux core is filled into the U-shaped groove, and the filling rate of the flux core is 28%; then the welding wire is obtained by closing, reducing the diameter, drawing, and winding.

[0058] During welding, the workpiece is preheated to 268°C, and then the workpiece is welded with a base wire. The thickness of the base layer is 3.7mm. The workpiece after base welding is unilaterally surfacing under the flux layer. When the thickness of the unilateral surfacing is about 30mm, it is tempered to eliminate welding stress. The tempering temperature is 489°C and the tempering time is 10h. After the furnace is cooled to 280°C, the surfacing operation is continued. After the surfacing is completed, the whole is tempered. The overall tempering temperature is 503°C and the tempering time is 10h. Then the workpiece is cooled to 46°C with the furnace and then taken out. In this embodiment, the current is controlled at 450-510A and the interlayer temperature is controlled at 200-250°C during welding. ;

[0059] Example 2

[0060] The cladding flux-cored welding wire of this embodiment includes a steel strip and a flux core filled in the steel strip, wherein the flux core includes the following components by mass percentage: 45% medium carbon ferrochrome, 15% metallic chromium, 5% metallic manganese, 7% ferrosilicon, 2.5% nickel powder, and the balance is iron powder. The steel strip is HS1 steel strip, the steel strip is rolled into a U-shaped groove, and then the mixed flux core is filled into the U-shaped groove, and the filling rate of the flux core is 24%; then the welding wire is obtained by closing, reducing the diameter, drawing, and winding.

[0061] In this embodiment, the welding method is the same as the welding method in Example 1, except that the preheating temperature of the workpiece is 277°C, the thickness of the base layer for base welding is 3.8 mm, the welding current is controlled at 460-495A, the interlayer temperature is controlled at 230-245°C, the partial tempering temperature is 495°C, and the tempering time is 8h; the overall tempering temperature is 485°C, the tempering time is 8h, and the furnace temperature is 48°C.

[0062] Example 3

[0063] The cladding flux-cored welding wire of this embodiment includes a steel strip and a flux core filled in the steel strip, wherein the flux core includes the following components by mass percentage: 55% medium carbon ferrochrome, 13% metallic chromium, 4% metallic manganese, 5% ferrosilicon, 2% nickel powder, and the balance is iron powder. The steel strip is HS1 steel strip, the steel strip is rolled into a U-shaped groove, and then the mixed flux core is filled into the U-shaped groove, and the filling rate of the flux core is 26%; then the welding wire is obtained by closing, reducing the diameter, drawing, and winding.

[0064] In this embodiment, the welding method is the same as the welding method in Example 1, except that the preheating temperature of the workpiece is 296°C, the thickness of the base layer for base welding is 3.8 mm, the welding current is controlled at 520-540A, the interlayer temperature is controlled at 236-248°C, the partial tempering temperature is 492°C, and the tempering time is 8.5h; the overall tempering temperature is 496°C, the tempering time is 8h, and the furnace temperature is 48°C.

[0065] Example 4

[0066] The cladding flux-cored welding wire of this embodiment includes a steel strip and a flux core filled in the steel strip, wherein the flux core includes the following components by mass percentage: 43% medium carbon ferrochrome, 12% metallic chromium, 3.5% metallic manganese, 5% ferrosilicon, 2% nickel powder, and the balance is iron powder. The steel strip is selected from HS1 steel strip, the steel strip is rolled into a U-shaped groove, and then the mixed flux core is filled into the U-shaped groove, and the filling rate of the flux core is 30%; then the welding wire is obtained by closing, reducing the diameter, drawing, and winding.

[0067] In this embodiment, the welding method is the same as the welding method in Example 1, except that the preheating temperature of the workpiece is 258°C, the thickness of the base layer for base welding is 3.6 mm, the welding current is controlled at 530-550A, the interlayer temperature is controlled at 235-250°C, the partial tempering temperature is 488°C, and the tempering time is 8.5h; the overall tempering temperature is 486°C, the tempering time is 10h, and the furnace temperature is 45°C.

[0068] According to the welding process of the present invention, various welding tests were carried out on the welding wires provided in the above-mentioned embodiments 1, 2, 3 and 4. The welding process and heat treatment parameters are shown in Table 1, and the chemical composition and properties of the deposited metal are shown in Table 2:

[0069] Table 1 Welding process parameters (submerged arc welding\HJ260 flux)

[0070]

[0071] Table 2 Chemical composition (%) and properties of deposited metal

[0072]

[0073] The test results of Examples 1 to 4 show that the flux-cored welding wire provided by the present invention has excellent wear resistance, and the deposited metal has high strength and hardness and good surface formability.

[0074] The cladding flux-cored welding wire of the present invention transitions alloy elements such as chromium, manganese, silicon, and nickel to the deposited metal. By adjusting the proportion of the alloy elements, the hardness and strength of the deposited metal can be improved, the wear resistance is good, and the metal has a certain toughness. The generation of cracks in the cladding layer deposited metal can be effectively controlled to prevent it from falling off, and the cladding layer deposited metal is suitable for repairing cold rolling rolls in the steel industry. Therefore, the present invention effectively overcomes some practical problems in the prior art and has a high utilization value and use significance.

[0075] 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 familiar with 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A cladding flux-cored welding wire, characterized in that: It comprises a steel strip and a flux core filled in the steel strip, wherein the flux core comprises the following components in percentage by mass: 40-55% of medium carbon ferrochrome, 9-17% of metallic chromium, 3-5% of metallic manganese, 5-8% of ferrosilicon, 2-3% of nickel powder, and the remainder is iron powder, wherein the carbon content of the medium carbon ferrochrome is 1-1.5 wt%, the chromium content is 78-85wt%, the ferrosilicon is 75# ferrosilicon, the silicon content of the ferrosilicon is 72-75 wt%, and the steel strip is HS1 steel strip.

2. The cladding flux-cored welding wire according to claim 1, characterized in that: The width of the steel strip is 14 mm to 18 mm, and the thickness of the steel strip is 0.3 mm to 0.6 mm.

3. The cladding flux-cored welding wire according to claim 1, characterized in that: The weight of the flux core in the cladding flux-cored welding wire is 20-30% of the total weight of the cladding flux-cored welding wire.

4. A method for preparing a cladding flux-cored welding wire, characterized in that: The steps include: Mixing the components of claim 1 uniformly to prepare a drug core; The steel strip is slitting, taping, cleaning, and then rolled into a U-shaped groove; Filling the drug core into the U-shaped groove; The steel strip filled with the flux core is closed, reduced in diameter, drawn and wound up to obtain the cladding flux cored welding wire.

5. A welding method for a cladding flux-cored welding wire according to claim 1, characterized in that: The steps include: Preheat the workpiece; Performing base welding on the workpiece using a base welding wire; The workpiece after the base welding is subjected to single-side surfacing welding under the flux layer, and then tempered and cooled; Repeat the above surfacing operation, and after all surfacing is completed, temper the whole body; Cool down and take out of the oven.

6. The welding method according to claim 5, characterized in that: The preheating temperature when preheating the workpiece is 250-300°C.

7. The welding method according to claim 5, characterized in that: The thickness of the base layer during the base welding is less than 4 mm.

8. The welding method according to claim 5, characterized in that: The welding current during the surfacing welding is 450-550A, the welding voltage is 28-32V, and the workpiece temperature during the welding process is 200-250°C; the tempering temperature during the tempering is 480-510°C, and the insulation time is 8-12h.

Images