High-hardness wear-resistant crack-free powder-cored wire for cladding

Abstract

The invention discloses a high-hardness wear-resistant crack-free cladding powder cored wire which is prepared by taking a 430 stainless steel strip as an outer layer wrapper and wrapping powder inside, the powder comprises the following components in percentage by mass: 1-4% of ferroboron, 5-8% of ferroniobium, 3-5% of ferrotitanium, 1-3% of graphite, 1-5% of chromium metal, 1-2% of ferrosilicon, 0.5-1% of electrolytic manganese, 1-3% of calcium fluoride and the balance of reduced iron powder, and the powder core filling rate is 20-28%. A low-carbon and low-chromium mode is adopted, so that the whole prepared Fe-Cr-C series cladding layer is in a hypoeutectic state, the cladding has relatively good toughness, and no crack is generated; and multiple elements are compounded to reinforce the performance of the cladding layer, and the hardness and wear resistance of the cladding layer are improved. When the powder-cored wire is used for cladding, a formed cladding layer is good in formability and free of surface cracks, air holes and internal air holes, and the powder-cored wire is applied to surface strengthening and remanufacturing repairing of wear-resisting parts in coal mine, metallurgy and cement engineering mechanical equipment and can be applied to working conditions with severe impact.

Description

Technical Field

[0001] The present invention belongs to the field of wear-resistant cladding, and is aimed at the remanufacturing repair of components in engineering equipment such as mines, coal, and cement, which can effectively improve the wear resistance of components and extend the service life of the cladded workpieces. Specifically, it relates to a high-hardness and super-wear-resistant crack-controllable cladding flux-cored wire. Background Art

[0002] Engineering mechanical equipment such as construction machinery and mining machinery often works under conditions such as sand, sediment, and corrosion. Their working components are often faced with heavy loads, impacts, and severe abrasive wear, resulting in the working surfaces of related components being prone to excessive wear and component failure. The application of remanufacturing repair technology can effectively improve the wear resistance of its working components. The Fe-Cr-C series flux-cored wire commonly used in remanufacturing repair technology has a wide application in the repair and remanufacturing of components in medium engineering equipment due to the low cost and good wear resistance of the prepared cladding layer. It mainly uses a large number of high-hardness carbides in the structure as wear-resistant phases, but this also leads to the characteristics of poor toughness and many cracks in the cladding layer, and it cannot be applied to harsh impact conditions. For the Fe-Cr-C series cladding layer without cracks, it is often achieved by reducing the formation of carbides in the structure and improving the toughness of the cladding layer, resulting in the characteristics of low hardness and insufficient wear resistance of the cladding layer. At present, developing a high-hardness, wear-resistant and crack-free Fe-Cr-C series cladding layer is a problem faced by the industry. Therefore, on the premise of ensuring that the Fe-Cr-C series cladding layer has good hardness and wear resistance, making the prepared cladding layer crack-free can make the wire have a wider application, extend the service life of the prepared cladding layer, and make the cladding layer withstand harsh impact conditions. Summary of the Invention

[0003] Object of the Invention: To solve the problem that cracks are easily formed in the preparation process of Fe-Cr-C series cladding, the present invention provides a high-hardness, wear-resistant and crack-free cladding flux-cored wire and its preparation method.

[0004] Technical Content: To achieve the above technical object, the present invention proposes a high-hardness, wear-resistant and crack-free cladding flux-cored wire, which includes a stainless steel strip and a powder. The powder is filled in the strip. The powder contains the following components in mass percentages: ferroboron 1-4%, ferroniobium 5-9%, ferrotitanium 3-5%, graphite 1-3%, metallic chromium 1-5%, ferrosilicon 1-2%, electrolytic manganese 0.5-1%, calcium fluoride 1-3%, and the balance is reduced iron powder and trace impurities.

[0005] Preferably, the skin of the wire is 430 cold-rolled stainless steel, the width of the strip is 11 mm, the thickness is 0.3 mm, and the length is not limited.

[0006] Preferably, the powder contains ferroboron, ferroniobium, ferrotitanium, graphite, metallic chromium, ferrosilicon, electrolytic manganese, and reduced iron powder.

[0007] Preferably, the powder contains calcium fluoride.

[0008] Preferably, the particle size of each raw material in the alloy powder is 60 - 100 mesh.

[0009] Preferably, when preparing the welding wire, a forming roll is used to roll the steel strip into a U shape, and then the powder is added into the U-shaped groove according to 20 - 28% of the total weight of the welding wire through a powder feeding device. The U-shaped groove is closed to wrap the powder inside, and through a wire drawing die, it is drawn and reduced in diameter step by step until the diameter reaches 1.2 - 1.6 mm.

[0010] Preferably: The microstructure of the cladding layer is optimized by multiple elements, and an arc stabilizer is added. During the cladding process, the arc is stable, the spatter is small, the formability of the cladding layer is good, and no cracks appear within 3 - 4 layers of the cladding layer.

[0011] Preferably: The microstructure of the cladding layer is hypoeutectic, but the microstructure of the cladding layer is optimized by elements such as Nb and B, so that the Rockwell hardness of the cladding layer is greater than 56 HRC and the Vickers hardness is greater than 800 HV 0.2 , and the relative wear resistance is 25 - 35 times that of Q345 steel.

[0012] Preferably: This welding wire can be used for surface strengthening and remanufacturing repair of wear-resistant components in mining, coal, and cement engineering machinery and equipment, and the prepared cladding layer can be applied to harsh impact working conditions.

[0010] The main functions of each component in the above-mentioned flux cored wire are as follows:

[0011] C and Cr elements: Generate high-hardness carbides common in high-chromium cast iron, improve hardness, and serve as wear-resistant phases; NbC formed by Nb elements can be dispersed at the austenite grain boundaries, which will hinder grain growth, achieve the purpose of refining grains, and indirectly promote the uniform distribution of the microstructure, improving the toughness of the cladding layer; B element: It can replace C atoms in the formed carbides, enabling more C atoms to participate in the eutectic reaction, generating more carbides, and increasing hardness.

[0012] The microstructure of the prepared cladding layer is composed of retained austenite, eutectic structure, and Nb(C,B) hard phases, belonging to hypoeutectic structure. The large distribution of retained austenite increases the toughness of the cladding layer, making the prepared cladding layer free of cracks. At the same time, the small-sized carbide hard phases generated in the microstructure improve the hardness and wear resistance of the cladding layer, achieving the purpose of the present invention.

[0013] Beneficial effects: (1) For the high-hardness, wear-resistant and crack-free clad flux-cored wire of the present invention, the microstructure of the clad layer is optimized by elements such as Nb, Ti, B, etc., so that a large number of dispersed Nb(C, B) composite carbides are formed in the prepared clad layer. Their dispersed distribution at the austenite grain boundaries will hinder grain growth, thereby achieving the purpose of grain refinement, enhancing the toughness of the clad layer, and making the prepared clad layer crack-free.

[0014] (2) For the high-hardness, wear-resistant and crack-free clad flux-cored wire of the present invention, the formula of the clad powder is optimized. For the cladding of construction machinery parts, the welding process is optimized, and the clad layer is not easy to peel off, prolonging the service life of related parts.

[0015] (3) For the high-hardness, wear-resistant and crack-free clad flux-cored wire of the present invention, the hardness of the clad layer is uniform, the average Rockwell hardness is in the range of 55 - 60 HRC, and the Vickers hardness is 800 - 900 HV0.2. The wear resistance is excellent, and the relative wear resistance of the clad layer is 25 - 35 times that of Q345.

[0016] (4) For the high-hardness, wear-resistant and crack-free clad flux-cored wire of the present invention, a mixed gas or pure argon is used as the shielding gas, and the gas metal arc welding or tungsten inert gas welding method is used for the cladding operation. An arc stabilizer is added to the powder to stabilize the welding current, improve the formability of the clad layer, and the arc is stable and the spatter is small during the cladding process, having good processability.

[0017] (5) For the high-hardness, wear-resistant and crack-free clad flux-cored wire of the present invention, the formability of the clad layer is good, and no cracks are generated on the surface. It can be applied to the remanufacturing and repair of engineering equipment in industries such as mines, coal, and excavation, and the prepared clad layer can be applied to severe working conditions such as impact. Description of the Drawings

[0018] The figure shows the morphology of the composite carbide in the high-hardness, wear-resistant and crack-free clad layer obtained in the embodiment of the present invention.

[0019] Figure 1 It is the scanning electron microscope image of the clad layer prepared in Example 1 of the present invention;

[0020] Figure 2 It is the three-dimensional wear profile of the clad layer prepared in Example 1 of the present invention.

[0021] Figure 3 It is the scanning electron microscope image of the clad layer prepared in Example 2 of the present invention;

[0022] Figure 4 It is the three-dimensional wear profile of the clad layer prepared in Example 2 of the present invention. Detailed Embodiments

[0023] According to Figures 1-4As shown in the following and the following embodiments, the present invention can be better understood. The present invention will be further explained below in conjunction with the embodiments. It should be understood that the ratio of the specific powder components, process conditions and their results described in the following embodiments are for better explaining the present invention, and do not constitute a limitation on the protection scope of the present invention.

[0024] The following cladding process parameters are used to prepare the cladding layer, and the following methods are used to characterize and test the cladding layer:

[0025] The cladding current is 240 - 290 A, the cladding voltage is 27 - 30 V, the feeding rate is 100 - 200 mm / min, the lap spacing is 7 - 8 mm, the shielding gas is a mixed gas of melting electrode with a volume fraction of (78 - 80% Ar + 22 - 20% CO2), the shielding gas flow rate is 15 L / min. The cladding layer is prepared by gas metal arc welding on the substrate. It should be noted that after each pass of welding, sufficient heat dissipation should be carried out before overlapping the next pass to prevent excessive deformation and deterioration of the forming performance caused by continuous heat input. Clad 3 - 4 layers.

[0026] The Rockwell hardness is measured using a HR - 150A Rockwell hardness tester with a load of 150 Kg. Five points are measured for hardness on each test sample, and the average hardness value is calculated.

[0027] The microhardness is measured using a Vickers hardness tester with a load of 200 g and a holding time of 10 seconds. Ten points are measured for hardness on each test sample, and the average hardness value is calculated.

[0028] At room temperature wear experiment, a wear test sample with a size of 12 * 12 * 8 mm3 is cut from the cladding layer of each embodiment. The wear test parameters are as follows: the diameter of the friction pair is 6 mm, the rotational speed is 50 revolutions per minute, the load is 200 N, the friction radius is 4.5 mm. The wear resistance of the cladding layer is measured by the weight loss during formal wear. Before and after each experiment, the sample is dried for 1 h and then weighed and recorded. Q345 steel is used as a comparison sample in the experiment, and the ratio of the weight loss of the comparison piece to the weight loss of the measured piece is used as the relative wear resistance of the cladding sample.

[0029] Example 1

[0030] A flux - cored wire for high - hardness, wear - resistant and crack - free cladding, comprising a stainless - steel strip and powder. The powder is filled in the strip. The percentage of the powder core component in the overall mass of the wire is as follows: Ferroboron 4% The powders taken are all passed through a 60 - mesh sieve. The various powders taken are placed in a powder mixer, mixed for 60 minutes, and dried for 60 minutes. The mixed powder is added to the U - shaped groove of a 430 stainless - steel strip, and drawn and reduced in diameter step by step, and finally a product with a wire diameter of 1.6 mm is obtained.

[0031] The cladding layer formed by the wire rod prepared in Example 1 has good formability, less spatter, beautiful formation, no cracks on the surface, and is characterized by high hardness and excellent wear resistance. The hardness and wear resistance of the cladding metal are shown in Table 1.

[0032] Example 2

[0033] A flux-cored wire for high-hardness, wear-resistant and crack-free cladding, comprising a stainless steel strip and a flux. The flux is filled in the strip. The percentage of the flux composition in the overall mass of the wire is as follows: All the powders taken pass through a 60-mesh sieve. The various powders taken are placed in a powder mixer, mixed for 60 minutes, and dried for 60 minutes. The mixed powder is added to the U-shaped groove of a 430 stainless steel strip, and drawn and reduced in diameter step by step. Finally, a product with a wire diameter of 1.6 mm is obtained.

[0034] The cladding layer formed by the wire rod prepared in Example 2 has good formability, less spatter, beautiful formation, no cracks on the surface, high hardness of the cladding layer and excellent wear resistance. The hardness and wear resistance of the cladding metal are shown in Table 1.

[0035] Table 1 Hardness and relative wear resistance of the cladding metal in each example. Example / Performance Rockwell hardness / HRC <![CDATA[Microhardness / HV 0.2 > Relative wear resistance Example 1 57 800 26 Example 2 59 850 30

[0036] Comparative Example 1

[0037] The flux-cored wire comprises a 430 stainless steel strip and a flux. The flux is filled in the strip. The percentage of the flux composition in the overall mass of the wire is as follows: The steel strip is rolled into a U-shaped groove, the flux is mixed and dried and then added, and a wire is obtained through rolling and drawing to reduce the diameter. The wire diameter is 1.6 mm.

[0038] There are a small number of micro-cracks on the surface of the cladding layer formed by the flux-cored wire in Comparative Example 1. There are no obvious hard-phase particles in its structure, and the microhardness is 500 HV 0.2 , the hardness is significantly reduced, and the wear resistance is poor.

[0039] Comparative Example 2

[0040] The flux-cored wire comprises a 430 stainless steel strip and a flux. The flux is filled in the strip. The percentage of the flux composition in the overall mass of the wire is as follows: The steel strip is rolled into a U-shaped groove, the flux is mixed and dried and then added, and a wire is obtained through rolling and drawing to reduce the diameter. The wire diameter is 1.6 mm;

[0041] The clad layer prepared by the flux-cored wire of Comparative Example 2 has transverse cracks on the surface, with poor surface formability. The microhardness and wear resistance are not much different from those of Example 1.

[0042] Comparative Example 3

[0043] The flux-cored wire includes a 430 stainless steel strip and a powder. The powder is filled in the strip. The mass percentage of the flux composition in the whole wire is as follows: The strip is rolled into a U-shaped groove, the powder is mixed and dried and then added, and the wire is obtained through rolling and wire drawing for diameter reduction. The wire diameter is 1.6 mm;

[0044] The clad layer prepared by the flux-cored wire of Comparative Example 3 has obvious transverse cracks on the surface. During the cladding process, the welding current is unstable, the spatter is large, and the bead formability is poor.

[0001] In the present invention, elements such as Nb and Ti are added to the powder to refine the structure of the clad layer and form MC-type carbide hard phases. At the same time, an appropriate amount of B element is added to increase the hardness of the clad layer; an appropriate amount of arc stabilizer is added to improve the formability of the clad layer, and a clad layer with high hardness, high wear resistance and no cracks is prepared. The flux-cored wire of the present invention has good welding process performance, obvious refinement of the alloy structure, uniform surface hardness of the clad layer, the average hardness is in the range of 57-59 HRC, and the wear resistance is about 25-35 times that of Q345.

Claims

1. A high-hardness, wear-resistant and crack-free cladding flux-cored wire, characterized in that: The welding wire is made with a 430 stainless steel strip as the outer sheath and powder wrapped inside. The mass percentage range of each component in the powder with respect to the overall welding wire is as follows: ferrosilicon boron 1 - 4%, ferroniobium 5 - 8%, ferrotitanium 3 - 5%, graphite 1 - 3%, metallic chromium 1 - 5%, ferrosilicon 1 - 2%, electrolytic manganese 0.5 - 1%, calcium fluoride 1 - 3%, and the balance is reduced iron powder. The powder core filling rate is 20 - 28%.

2. The high-hardness wear-resistant crack-free cladding flux-cored wire according to claim 1, wherein: The particle size of each raw material in the said powder is 60 - 100 mesh.

3. The high-hardness, wear-resistant, crack-free cladding flux-cored wire according to claim 1, characterized in that: The skin of the said welding wire is a 430 cold-rolled stainless steel strip, with the strip width being 11 mm and the thickness being 0.3 mm.

4. The high-hardness, wear-resistant, crack-free clad flux-cored wire according to claim 1, wherein, When preparing the said welding wire, the steel strip is rolled into a U shape using a forming roll, then the powder is added into the U-shaped groove at 20 - 28% of the total weight of the welding wire through a powder feeding device. The U-shaped groove is closed to wrap the powder inside, and through a wire drawing die, it is drawn and the diameter is reduced step by step until the final diameter reaches 1.2 - 1.6 mm.

5. The high-hardness, wear-resistant and crack-free clad flux-cored wire according to claim 1, wherein: By optimizing the cladding layer structure with multiple elements and adding an arc stabilizer, during the cladding process, the arc is stable, the spatter is small, the formability of the cladding layer is good, and no cracks appear within 3 - 4 layers of the cladding layer.

6. The high-hardness wear-resistant crack-free cladding flux-cored wire according to claim 1, wherein: The microstructure of the cladding layer is hypoeutectic. However, by optimizing the microstructure of the cladding layer with elements such as Nb and B, the Rockwell hardness of the cladding layer is greater than 56 HRC, and the Vickers hardness is greater than 800 HV. 0.2 The relative wear resistance is 25 to 35 times that of Q345 steel.

7. A high-hardness wear-resistant crack-controllable cladding flux-cored wire according to claim 1, characterized in that: This welding wire can be used for surface strengthening and remanufacturing repair of wear-resistant components in mining, coal, and cement engineering mechanical equipment, and the prepared cladding layer can be applied to severely impacted working conditions.

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