Powder core wire for laminar cooling roller surface surfacing and preparation method of powder core wire

Abstract

The invention relates to the technical field of powder core wires, in particular to a powder core wire for laminar flow cooling roller surface overlaying and a preparation method of the powder core wire. According to the specific technical scheme, the powder core comprises ferrosilicon, electrolytic manganese, high-carbon ferrochrome, high-purity chromium powder, nickel powder, ferromolybdenum, ferroboron or boron carbide and reduced iron powder. The method not only improves the utilization rate of the material, but also realizes an efficient and low-cost production process, conforms to the national major strategic development goals of carbon reaching, carbon neutralization and the like, and provides powerful technical support for promoting green manufacturing and low-carbon industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of powder core wire, and particularly relates to a powder core wire for surfacing a laminar flow cooling roller and a preparation method thereof. BACKGROUND

[0002] The laminar flow cooling roller is used for uniformly cooling high-temperature steel plates in a hot rolling process, is usually exposed to a high-temperature environment of 400-600 DEG C for a long time, bears thermal-mechanical coupling stress and is washed by water / gas mixed medium. Its main failure modes include: (1) thermal fatigue cracks caused by alternating thermal stress and extending along the grain boundary; (2) the peeling of the oxide skin on the roller surface, which increases the surface roughness and further accelerates the wear failure; (3) high-temperature creep and local plastic deformation cause the deterioration of the roller shape accuracy; (4) the pitting and stress corrosion cracking caused by the corrosion of the cooling medium. The failure process presents a multi-mechanism coupling characteristic, which seriously affects the cooling uniformity of the steel plate and the stability of the production line.

[0003] In order to overcome the problems of wear, corrosion and thermal stress of the laminar flow cooling roller in the use process, at present, many research units have adopted laser cladding technology, and the Fe-based alloy powder (such as RockitR 431SR) with wear resistance and corrosion resistance is cladded on the surface of the laminar flow cooling roller, which significantly improves the corrosion resistance and wear resistance of the roller surface, and strengthens the thermal fatigue performance of the roller body. In addition, the laser cladding layer has excellent adhesion and compactness, which can effectively resist the influence of high temperature and harsh chemical environment, thereby significantly prolonging the service life of the laminar flow cooling roller (from 12 months to more than 24 months). However, when laser cladding is carried out on the surface of the laminar flow cooling roller, due to its low heat input and high cooling rate, a large thermal stress is easily generated in the material, and then cracks are formed; the low dilution rate of laser cladding causes the organization mutation at the interface, and brittle intermetallic compounds may be precipitated, which enhances the crack propagation tendency; the microstructure formed by laser cladding is generally fine columnar crystal, the grain boundary directionality is strong, and the crack propagation is easy to propagate along the grain boundary, thereby aggravating the cracking risk. In addition, the high cost and slow cladding rate of the Fe-based alloy powder increase the cost of the product. Therefore, it is urgent to explore an economic and efficient alternative wear-resistant and corrosion-resistant material and cladding technology to reduce the cost and improve the production efficiency. SUMMARY

[0004] To overcome the shortcomings of the prior art, the application provides a powder core wire for surface overlaying of a laminar flow cooling roller and a preparation method thereof, which solves the problems of high cost and low efficiency in the traditional laser cladding process. The wire provided by the application can significantly improve the cladding efficiency while ensuring high wear resistance and corrosion resistance, thereby reducing energy consumption and material waste and effectively reducing the overall production cost. At the same time, the service life is prolonged, the maintenance frequency is reduced, and the production efficiency is effectively improved. In addition, electric arc surfacing has better crack resistance than laser cladding. Electric arc surfacing has high heat input and low cooling rate, which reduces thermal stress and crack generation caused by excessive temperature gradient; high dilution rate and smooth transition of interface composition of electric arc surfacing help to reduce the precipitation of brittle phases, and slower solidification enhances the crack propagation resistance. At the same time, the method meets the demand of the national major strategic development goal of carbon peak and carbon neutrality, and also provides strong support for realizing efficient and low-carbon industrial production.

[0005] To achieve the above object, the application is implemented by the following technical solutions:

[0006] The application discloses a powder core, which comprises the following components: ferrosilicon, electrolytic manganese, high-carbon chromium iron, high-purity chromium powder, nickel powder, molybdenum iron, boron iron or boron carbide, and reduced iron powder.

[0007] Preferably, the powder core comprises the following elements in terms of mass percentage: C 0.4-1%, Si 4-8%, Mn 1-3%, Cr 5-31%, Ni 7-11%, Mo 9-12%, B 4-8%, and the rest is Fe.

[0008] Preferably, the silicon content in the ferrosilicon is 70-75 wt.%, the manganese content in the electrolytic manganese is greater than 99.9 wt.%, the carbon content in the high-carbon chromium iron is 6-8 wt.%, the chromium content is 60-70 wt.%, the chromium content in the high-purity chromium powder is greater than 99.9 wt.%, the nickel content in the nickel powder is greater than 99.9 wt.%, the molybdenum content in the molybdenum iron is 50-60 wt.%, the boron content in the boron iron is 18-25 wt.% or the boron content in the boron carbide is 75-78 wt.%, and the iron content in the powder core is greater than 98.5 wt.%.

[0009] Preferably, the particle size of the powder core is 50-120 mu m.

[0010] Correspondingly, a powder core wire for surface overlaying of a laminar flow cooling roller is provided, and the raw material of the powder core wire comprises the powder core.

[0011] Preferably, the filling rate of the powder core in the powder core wire is 18-28%.

[0012] Correspondingly, a preparation method of the powder core wire for the surface overlay welding of the laminar flow cooling roller comprises the following steps of: wrapping the powder core with a metal shell.

[0013] Preferably, the method comprises the following steps:

[0014] (1) respectively weighing ferrosilicon, electrolytic manganese, high-carbon chromium iron, high-purity chromium powder, nickel powder, ferromolybdenum, boron iron or boron carbide powder and reduced iron powder; respectively drying at 150 DEG C for 2h, and then uniformly mixing;

[0015] (2) processing the metal shell into a U-shaped groove structure, and uniformly filling the uniformly mixed powder into the U-shaped groove;

[0016] (3) closing the U-shaped groove, so that the U-shaped groove is preliminarily formed into a circular wire; and then sequentially passing through multiple drawing dies to reduce the diameter, so that the diameter size of the finished product is reached.

[0017] Correspondingly, a welding method of the powder core wire for the surface overlay welding of the laminar flow cooling roller prepared by using the preparation method comprises the following steps of: using a welding process to directionally deposit the powder core wire for the surface overlay welding of the laminar flow cooling roller on the surface of the laminar flow cooling roller.

[0018] Preferably, the welding process used comprises but is not limited to shielded metal arc welding, non-shielded metal arc welding and cold metal transfer welding.

[0019] The present application has the following advantages:

[0020] 1. The powder core wire provided by the present application has a relatively low overall production cost, can effectively replace the stainless steel powder used in the traditional laser cladding process, thereby reducing the economic burden of industrial production and improving the overlay welding efficiency.

[0021] 2. By optimizing the component ratio of the powder core wire, the present application significantly improves the hardness and wear resistance of the surface of the laminar flow cooling roller after overlay welding, prolongs the service life and improves the production stability.

[0022] 3. The present application improves the material utilization rate while realizing an efficient and low-energy-consumption manufacturing process, which meets the major strategic development goals of carbon peak and carbon neutrality, and provides technical support for promoting green manufacturing and low-carbon industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The surface macroscopic morphology of the powder core wire prepared in Example 3 after overlay welding;

[0024] Figure 2 The metallographic picture of the powder core wire prepared in Example 3 after overlay welding. DETAILED DESCRIPTION

[0025] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

[0026] If not specifically indicated, the technical means used in the examples is the conventional means familiar to those skilled in the art.

[0027] The present application discloses a kind of powder core, the powder core includes the following components: ferrosilicon, electrolytic manganese, high-carbon chromium iron, high-purity chromium powder, nickel powder, ferromolybdenum, boron iron or boron carbide, reduced iron powder.The particle size of the powder core is 50-120 μm.

[0028] Among them, the silicon content in the ferrosilicon is 70-75 wt.%, the manganese content in the electrolytic manganese is greater than 99.9 wt.%, the carbon content in the high-carbon chromium iron is 6-8 wt.%, the chromium content is 60-70 wt.%, the chromium content in the high-purity chromium powder is greater than 99.9 wt.%, the nickel content in the nickel powder is greater than 99.9 wt.%, the molybdenum content in the ferromolybdenum is 50-60 wt.%, the boron content in the boron iron is 18-25 wt.% or the boron content in the boron carbide is 75-78 wt.%, and the iron content in the powder core is greater than 98.5 wt.%.

[0029] Further, the powder core includes the following elements in terms of mass percentage: C 0.4-1%, Si 4-8%, Mn 1-3%, Cr 5-31%, Ni 7-11%, Mo 9-12%, B 4-8%, and the rest is Fe.

[0030] The present application provides a kind of powder core wire for surface build-up welding of laminar flow cooling roll, the raw material of the powder core wire includes the powder core described.The filling rate of powder core in the powder core wire is 18-28%.

[0031] The present application provides a kind of preparation method of the powder core wire for surface build-up welding of laminar flow cooling roll described, the powder core is wrapped with metal shell.Metal shell can be stainless steel belt, as one of the implementation ways, steel belt width is 12mm, thickness is 0.3mm.

[0032] Specifically includes the following steps:

[0033] (1) respectively, ferrosilicon, electrolytic manganese, high-carbon chromium iron, high-purity chromium powder, nickel powder, ferromolybdenum, boron iron or boron carbide powder and reduced iron powder are weighed, to ensure that the total mass percentage of each component is 100%;The weighed powder is dried at 150 DEG C for 2h, then the powder is uniformly mixed by adopting powder mixer, to ensure the uniformity of powder distribution;

[0034] (2) using rolling process to process the steel strip into U-shaped groove structure, and filling the mixed and uniform powder into the U-shaped groove through a special filling machine according to a filling rate of 18-28%, so as to ensure the stability and uniformity of the powder core filling;

[0035] (3) using a forming roller machine to close the U-shaped groove, so that the U-shaped groove is preliminarily formed into a circular wire; then sequentially passing through multiple drawing dies for reducing the diameter, after preliminary drawing, further precise drawing is carried out, so that the wire finally reaches the target diameter (such as 1.2 mm), the formed powder core wire is neatly wound on a standard welding wire reel, and quality inspection and packaging are carried out.

[0036] The application provides a welding method of the powder core wire for surface overlaying of a laminar flow cooling roller prepared by using the preparation method.

[0037] When the shielded metal arc welding is selected, the welding parameters are as follows: the welding voltage is 20-25 V, the welding current is 160-180 A, the wire feeding speed is 7.8 mm / s, 80% Ar+20% CO2 mixed gas is used as the protective gas during the welding process, and the dry elongation is 15-20 mm.

[0038] The application will be further described below in combination with specific examples.

[0039] Example 1

[0040] The components are weighed according to the following percentages, and the components are weighed respectively, and the mass percentages of 6% ferrosilicon, 1% electrolytic manganese, 7% high-carbon chromium iron, 2% high-purity chromium powder, 7% nickel powder, 15% molybdenum iron, 20% boron iron, and the balance is reduced iron powder. The powder particle size is 50-120 μm.

[0041] After the above powder is dried in a drying oven at 150 DEG C for 2h, the powder is uniformly mixed by using a powder mixer, so as to ensure the uniformity of the powder distribution.

[0042] The preparation method of the powder core wire for surface overlaying of a laminar flow cooling roller disclosed in the application is used, the mixed and uniform powder is uniformly filled into the U-shaped groove of the steel strip according to a filling rate of 18%, and the drawing die is used for reducing the diameter, so that the wire finally reaches the target diameter of 1.2 mm.

[0043] The powder core wire is deposited on the surface of the laminar flow cooling roller by using the process of gas tungsten arc welding. The welding parameters are as follows: the welding voltage is 20-25V, the welding current is 160-180A, the wire feeding speed is 7.8mm / s, and the mixed gas of 80% Ar+20% CO2 is used as the protective gas during the welding process, and the dry elongation is 15-20mm.

[0044] After the surfacing, the sample is taken by using the electric spark cutting machine, and then the sample is polished flat by using the sandpaper. The mass percentage composition of the surface of the laminar flow cooling roller after the surfacing is measured by using the full spectrum direct reading spectrometer, and the mass percentage composition is as follows: C 0.09%, Si 1.23%, Mn 0.78%, Cr 14.75%, Ni 1.97%, Mo 1.08%, B 0.46%, and the rest is Fe.

[0045] The Rockwell hardness of the surfacing alloy is tested by using the HR-150A Rockwell hardness tester, and the Rockwell hardness of the surface of the laminar flow cooling roller after the surfacing is 51.50HRC. In the friction and wear test, the wear scar is manufactured by using the MS-HT1000 high temperature friction and wear tester, and the cross-sectional area of the wear scar is 0.0640mm 2 .

[0046] Example 2

[0047] The components are weighed according to the following percentages, and the mass percentage of each component is as follows: 7% ferrosilicon, 2% electrolytic manganese, 7% high-carbon chromium iron, 7% high-purity chromium powder, 8% nickel powder, 16% molybdenum iron, 30% boron iron, and the rest is reduced iron powder. The particle size of the powder is 50-120μm.

[0048] After the powder is dried in the drying oven at 150℃ for 2h, the powder is uniformly mixed by using the powder mixer to ensure the uniformity of the powder distribution.

[0049] According to the preparation method of the powder core wire for surfacing the surface of the laminar flow cooling roller disclosed in the present application, the uniformly mixed powder is uniformly filled into the U-shaped groove of the steel strip according to the filling rate of 24%, and the drawing die is used for reducing the diameter, so that the wire finally reaches the target diameter of 1.2mm.

[0050] The powder core wire is deposited on the surface of the laminar flow cooling roller by using the process of gas tungsten arc welding. The welding parameters are the same as those in example 1.

[0051] After the surfacing, the sample is taken by using the electric spark cutting machine, and then the sample is polished flat by using the sandpaper. The mass percentage composition of the surface of the laminar flow cooling roller after the surfacing is measured by using the full spectrum direct reading spectrometer, and the mass percentage composition is as follows: C 0.16%, Si 1.83%, Mn 0.92%, Cr 17.19%, Ni 2.03%, Mo 1.34%, B 0.58%, and the rest is Fe.

[0052] The Rockwell hardness of the surfacing alloy is tested by using a HR-150A Rockwell hardness tester, and the Rockwell hardness of the surface of the laminar flow cooling roller after surfacing is 55.98 HRC. In the friction and wear test, an MS-HT1000 high-temperature friction and wear tester is used to manufacture a wear scar, and the cross-sectional area of the wear scar is 0.0445mm 2 .

[0053] Example 3

[0054] The components are weighed according to the following percentages, and the components are weighed respectively, and the mass percentages of 8% ferrosilicon, 3% electrolytic manganese, 10% high-carbon chromium iron, 15% high-purity chromium powder, 11% nickel powder, 17% molybdenum iron, and 35% boron iron are weighed, and the balance is reduced iron powder. The powder particle size is 50-120μm.

[0055] After the above powder is dried in a drying oven at 150℃ for 2h, the powder is uniformly mixed by using a powder mixer to ensure the uniformity of the powder distribution.

[0056] According to the preparation method of the powder core wire for surfacing the surface of the laminar flow cooling roller disclosed in the present application, the uniformly mixed powder is uniformly filled into the U-shaped groove of the steel strip according to a filling rate of 28%, and a drawing die is used for reducing the diameter, so that the wire finally reaches a target diameter of 1.2mm.

[0057] The above powder core wire is deposited on the surface of the laminar flow cooling roller by using the gas tungsten arc welding process. The welding parameters involved are the same as in Example 1. The macroscopic morphology of the surface after surfacing is shown in Figure 1 The results show that the surfacing layer is relatively flat, and no obvious macroscopic defects are found, indicating that the welding formability is good. The metallographic structure of the surface of the surfacing layer is shown in Figure 2 The results show that the metallographic structure exhibits dendritic structure, and the appearance of the dendritic structure is attributed to high heat input and large temperature gradient during the welding process. At the same time, no microcracks or pores are found in the metallographic structure.

[0058] After surfacing, the sample is taken by using an electric spark cutting machine, and then the sample to be tested is polished flat by using sandpaper. The mass percentage composition of the surface of the laminar flow cooling roller after surfacing is measured by using a full-spectrum direct-reading spectrometer: C 0.31%, Si 2.47%, Mn 1.50%, Cr 19.22%, Ni 2.77%, Mo 2.01%, B 0.93%, and the balance is Fe.

[0059] The HR-150A Rockwell hardness tester is used to test the Rockwell hardness of the surfacing alloy, and the Rockwell hardness of the surface of the laminar flow cooling roller after surfacing is 60.62HRC. In the friction and wear test, the MS-HT1000 high temperature friction and wear tester is used to manufacture the wear scar, and the cross-sectional area of the wear scar is 0.0132mm 2 .

[0060] The above-described embodiments are only to describe the preferred modes of the present application, and are not intended to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A powder core, characterized in that: The powder core comprises the following components: ferrosilicon, electrolytic manganese, high carbon ferrochrome, high purity chromium powder, nickel powder, ferromolybdenum, ferroboron or boron carbide, and reduced iron powder.

2. A powder core according to claim 2, characterized in that: Calculated by mass percentage, the powder core includes the following elements: C 0.4-1%, Si 4-8%, Mn 1-3%, Cr 5-31%, Ni 7-11%, Mo 9-12%, B 4-8%, and the rest is Fe.

3. A powder core according to claim 1, characterized in that: The silicon content in the ferrosilicon is 70-75wt.%, the manganese content in the electrolytic manganese is greater than 99.9wt.%, the carbon content in the high-carbon ferrochromium is 6-8wt.%, the chromium content is 60-70wt.%, the chromium content in the high-purity chromium powder is greater than 99.9wt.%, the nickel content in the nickel powder is greater than 99.9wt.%, the molybdenum content in the ferromolybdenum is 50-60wt.%, the boron content in the ferroboron is 18-25wt.% or the boron content in the boron carbide is 75-78wt.%, and the iron content in the powder core is greater than 98.5wt.%.

4. A powder core according to any one of claims 1 to 3, characterized in that: The particle size of the powder core is 50-120 μm.

5. A powder cored wire for laminar cooling roll surface surfacing, characterized in that: The raw material of the powder core wire comprises the powder core according to any one of claims 1 to 4.

6. The powder-cored wire for laminar cooling roll surface surfacing according to claim 5, characterized in that: The filling rate of the powder core in the powder core wire material is 18-28%.

7. A method for preparing a powder-cored wire for laminar cooling roll surface surfacing according to claim 5 or 6, characterized in that: The powder core is wrapped with a metal shell.

8. The preparation method according to claim 7, characterized in that: The following steps are involved: (1) Weigh ferrosilicon, electrolytic manganese, high carbon ferrochrome, high purity chromium powder, nickel powder, ferromolybdenum, ferroboron or boron carbide powder, and reduced iron powder respectively; dry them at 150° C. for 2 h, and then mix them evenly; (2) Processing the metal shell into a U-shaped groove structure and filling the mixed powder evenly into the U-shaped groove; (3) The U-shaped groove is closed to initially form a round wire; then the wire is reduced in diameter through multiple drawing dies to reach the required diameter size of the finished product.

9. A welding method for laminar cooling roll surface surfacing using a powder-cored wire prepared by the preparation method according to any one of claims 6 to 8, characterized in that: The powder core wire for surfacing welding on the surface of the laminar cooling roller is directionally deposited on the surface of the laminar cooling roller by adopting a welding process.

10. The welding method according to claim 9, wherein: The welding processes used include but are not limited to metal inert gas welding, non-metal inert gas welding and cold metal transfer welding.

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