High-hardness super-wear-resistant crack-controllable cladding powder-cored wire

Abstract

The invention discloses a high-hardness super-wear-resistant crack-controllable cladding powder cored wire which is prepared by taking a 430 stainless steel strip as a sheath and wrapping powder inside, and the powder comprises the following components in percentage by mass: 1-4% of ferroboron, 5-8% of ferroniobium, 3-5% of ferrotitanium, 3.5-5% of graphite, 7-14% of chromium metal, 1-2% of ferrosilicon, 1-1.5% of electrolytic manganese, 1-3% of calcium fluoride, 1-2% of aluminum oxide and the balance of reduced iron powder. The powder core filling rate is 25-30%, the welding wire adopts multiple elements for compounding to reinforce the performance of a cladding layer, optimize the structure of the cladding layer and enhance the toughness of the cladding layer, and the cladding layer has few cracks; and the prepared cladding layer has high hardness and high wear resistance. The powder-cored wire is used for cladding, a formed cladding layer is good in formability and free of surface and internal air holes, and the powder-cored wire can be applied to remanufacturing and repairing of parts in engineering equipment such as mines, coal and cement and strengthening and repairing of small parts or thin-wall parts and can bear slight impact loads.

Description

Technical Field

[0001] The present invention belongs to the field of wear-resistant cladding, and is aimed at the remanufacturing and repair of parts in engineering equipment such as mines, coal, and cement, and specifically relates to a high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire. Background Art

[0002] Fe-Cr-C powder-cored welding wire, used in remanufacturing and repair technologies, is often used for surface strengthening and remanufacturing of wear-resistant parts in engineering machinery and equipment, such as mining, coal mining, and cement. The Fe-Cr-C cladding produced by this wire boasts high hardness, excellent wear resistance, and low cost. While this utilizes coarse carbides formed in the microstructure as wear-resistant phases, while offering excellent wear resistance, it also leads to intergranular fracture within the cladding layer during fabrication, often resulting in numerous cracks on the surface when exposed to extreme temperature and stress gradients within the molten pool. If this cladding layer is subjected to impact loads, stress concentration may occur, leading to chipping and shedding, resulting in component failure. To address the harsh service environments encountered in engineering applications, Fe-Cr-C cladding layers must possess both high wear resistance and adequate impact resistance to prevent the formation of numerous cracks during fabrication. Arc stabilizers are also added to optimize the cladding's formability, resulting in a high-hardness, excellent wear resistance, minimal cracking, and aesthetically pleasing finish. Furthermore, the Fe-Cr-C powder-cored welding wire commonly used in engineering applications is thick and relatively large, such as φ2.4mm. This is insufficient for strengthening and repairing smaller or thin-walled parts. To address this, the development of a highly hard, wear-resistant, crack-controllable powder-cored welding wire with a diameter of φ1.2-1.6mm could make Fe-Cr-C powder-cored welding wire more suitable for the remanufacturing and repair of engineering machinery. Summary of the Invention

[0003] Purpose of the invention: In order to solve the problem that hypereutectic Fe-Cr-C cladding layers are prone to forming many cracks during the preparation process, improve the wear resistance of the Fe-Cr-C cladding layers, and enable the welding wire to be used for the remanufacturing and repair of small components and thin-walled parts, the present invention provides a high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire.

[0004] Technical content: To achieve the above technical objectives, the present invention proposes a high-hardness, ultra-wear-resistant, crack-controlled cladding powder-cored welding wire, comprising a stainless steel strip and powder, the powder being filled in the steel strip. The powder comprises the following components, and the mass percentage of each powder in the overall welding wire is in the following range: 1-4% ferroboron, 5-8% ferroniobium, 3-5% ferrotitanium, 3-5% graphite, 7-14% metallic chromium, 1-2% ferrosilicon, 1-1.5% electrolytic manganese, 1-6% calcium fluoride, 1-2% aluminum oxide, and the remainder being reduced iron powder and trace impurities.

[0005] Preferably, the medicine powder comprises: ferroboron, ferroniobium, ferrotitanium, graphite, metallic chromium, ferrosilicon, electrolytic manganese, calcium fluoride, aluminum oxide, and reduced iron powder.

[0006] Preferably, the particle size of each raw material in the alloy powder is 60-100 mesh.

[0007] Preferably, the welding wire surface is 430 cold-rolled stainless steel, the steel strip width is 11 mm, the thickness is 0.3 mm, and the length is not limited.

[0008] Preferably, the welding wire is formed by rolling a 430 stainless steel strip into a U-shape using a forming roller, and then adding flux core powder according to 25-30% of the total weight of the welding wire into the U-shaped groove through a powder feeding device. The U-shaped groove is then closed to wrap the flux core therein, and the wire is drawn and reduced in diameter step by step through a wire drawing die, and finally the diameter reaches 1.2-1.6 mm to obtain the final product.

[0009] The main functions of the above-mentioned powder are as follows:

[0010] Si and Mn elements are mainly used for deoxidation during the cladding process; Nb and Ti elements generate small particles of hard phase, strengthen the cladding layer structure and refine the grains; B element can replace C atoms in the formed carbides, increase the amount of carbide precipitation, and perform solid solution strengthening on the structure; C and Cr elements are transition alloy elements in the cladding layer. Cr element can generate high hardness carbides commonly found in high chromium cast iron, such as M7C3, M3C, M 23 C6, these carbides can increase the hardness of the cladding layer and act as wear-resistant phases to improve the wear resistance of the cladding layer. Calcium fluoride and aluminum oxide can stabilize the welding current and act as arc stabilizers to reduce spatter and improve the formability of the cladding layer.

[0011] The cladding layer produced is composed of austenite, eutectic structure, primary carbides, and Nb(C,B) hard phases. The carbides produced are significantly smaller in size, and the hard phase particles are evenly distributed. The cladding layer has an aesthetically pleasing surface, free of impurities, pores, and other defects, with only a few microcracks present, achieving the objectives of the present invention.

[0012] Beneficial Effects: (1) The invention discloses a high-hardness, ultra-wear-resistant, crack-controllable cladding powder-cored welding wire. A large amount of dispersed Nb(C,B) composite carbides are formed in the cladding layer. These carbides act as heterogeneous nucleation cores to promote nucleation. Their dispersed distribution on the austenite grain boundaries hinders grain growth, thereby achieving the purpose of grain refinement and reducing the size of primary carbides from approximately 200 μm to approximately 100 μm. The smaller grain size can reduce the splitting effect of carbides on the structure, improve the toughness of the cladding layer, reduce cracks in the cladding layer, and achieve crack controllability in the cladding layer.

[0013] (2) The high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire described in the present invention uses a mixed gas or pure argon as a shielding gas, and uses metal-shielded arc welding or tungsten-arc argon welding to perform the cladding operation, and adds calcium fluoride and aluminum oxide to the powder to make the cladding layer have good formability, the arc is stable during the cladding process, the spatter is small, and the process has good processability.

[0014] (3) The high-hardness, ultra-wear-resistant, crack-controlled cladding powder-cored welding wire described in the present invention achieves uniform hardness and excellent wear resistance by synergistically strengthening the cladding layer with Nb, Ti, and B elements. Compared with traditional Fe-Cr-C cladding layers, the hardness and wear resistance are significantly improved, and cracks are reduced.

[0015] (4) The high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire described in the present invention can be used for the remanufacturing and repair of engineering equipment in the mining, coal, excavation and other industries, and the prepared cladding layer can withstand a certain impact load; at the same time, the welding wire has a relatively thin diameter of 1.2 to 1.6 mm, and can also be used for the remanufacturing and repair of small components and thin-walled parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The figure shows the morphology of composite carbides in the high-hardness, ultra-wear-resistant, crack-controlled cladding layer obtained in an embodiment of the present invention.

[0017] Figure 1 is a scanning electron microscope image of the cladding layer prepared in Example 1 of the present invention;

[0018] Figure 2 This is a three-dimensional contour diagram of the wear of the cladding layer prepared in Example 1 of the present invention.

[0019] Figure 3 is a scanning electron microscope image of the cladding layer prepared in Example 2 of the present invention;

[0020] Figure 4 This is a three-dimensional contour diagram of the wear of the cladding layer prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0021] According to the following examples and Figure 1-4 The present invention can be better understood as shown. The present invention is further explained below in conjunction with the examples. It is understood that the specific ratios of the core components, process conditions and results described in the following examples are for the purpose of better explaining the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0022] The cladding layer was prepared using the following cladding process parameters, and the cladding layer was characterized and tested using the following methods:

[0023] The cladding current is 240-290A, the cladding voltage is 27-30V, the feed rate is 100-200mm / min, the overlap spacing is 7-8mm, the shielding gas is a mixed gas of 78-80% Ar + 22-20% CO2 by volume, and the shielding gas flow rate is 15L / min. The cladding layer is prepared by cladding on the substrate using cladding gas shielded welding. It should be noted that each weld should be fully cooled before overlapping the next weld to prevent excessive deformation and decreased formability caused by continuous heat input. 3-4 layers are clad.

[0024] The Rockwell hardness was measured using a HR~150A Rockwell hardness tester with a load of 150 kg. Five points of each test sample were taken to test the hardness and the average hardness value was calculated.

[0025] The microhardness was measured using a Vickers hardness tester with a load of 200 g and a holding time of 10 seconds. Ten points of hardness were taken for each test sample, and the average hardness value was calculated.

[0026] For room-temperature wear tests, a wear specimen measuring 12 x 12 x 8 mm³ was cut from the cladding layer of each example. The wear test parameters were as follows: friction pair diameter 6 mm, rotation speed 50 rpm, load 200 N, and friction radius 4.5 mm. The wear resistance of the cladding layer was measured by weight loss during formal wear. Before and after each test, the specimen was dried for 1 hour and weighed. Q345 steel was used as a control specimen. The ratio of the weight loss of the control specimen to the weight loss of the test specimen was used as the relative wear resistance of the cladding specimen.

[0027] Example 1

[0028] A high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire comprises a 430 stainless steel strip and powder, wherein the powder is filled in the steel strip, and the mass percentage of the powder component in the entire welding wire is as follows: All powders were passed through a 60-mesh sieve. The various powders were placed in a powder mixer, mixed for 60 minutes, and dried for 60 minutes. The mixed powders were then added to a U-shaped 430 stainless steel strip groove, filling it at a 27% fill rate. The wire was then drawn and reduced in diameter, ultimately yielding a 1.6mm diameter welding wire.

[0029] The cladding layer prepared by the welding wire of Example 1 has good formability, stable welding current, low spatter, beautiful shape, few surface cracks, high hardness and excellent wear resistance. The hardness and wear resistance of the cladding metal are shown in Table 1.

[0030] Example 2

[0031] A high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire comprises a stainless steel strip and powder, wherein the powder is filled in the steel strip, and the percentage of the powder core component in the overall mass of the welding wire is as follows: All powders were passed through a 60-mesh sieve. The various powders were placed in a powder mixer, mixed for 60 minutes, and dried for 60 minutes. The mixed powders were then added to a U-shaped 430 stainless steel strip groove, filling it at a 27% fill rate. The wire was then drawn and reduced in diameter, ultimately yielding a 1.6mm diameter welding wire.

[0032] The cladding layer prepared by the welding wire of Example 2 has good formability, less spatter, beautiful shape, few surface cracks, high hardness and excellent wear resistance. The hardness and wear resistance of the cladding metal are shown in Table 1.

[0033] Table 1 Hardness and relative wear resistance of cladding metal in various examples. Examples / Performance Rockwell hardness / HRC <![CDATA[Microhardness / HV 0.2 > Relative wear resistance Example 1 61 1000 40 Example 2 60 950 27

[0034] Comparative Example 1

[0035] The powder cored wire consists of a 430 stainless steel strip and flux, which is filled in the strip. The percentage of the powder core component in the overall wire mass is as follows: The steel strip is rolled into a U-shaped groove, the powder is mixed and dried and then added, and the welding wire is obtained by rolling and drawing to reduce the diameter, and the welding wire diameter is 1.6mm;

[0036] The cladding layer prepared by the powder cored wire of comparative example 1 has many transverse cracks on the surface and the microhardness is 850HV 0.2 , wear resistance is poor.

[0037] Comparative Example 2

[0038] The powder cored wire consists of a 430 stainless steel strip and flux, which is filled in the strip. The percentage of the powder core component in the overall wire mass is as follows: The steel strip is rolled into a U-shaped groove, the powder is mixed and dried and then added, and the welding wire is obtained by rolling and drawing to reduce the diameter, and the welding wire diameter is 1.6mm;

[0039] The cladding layer prepared by the powder cored wire of comparative example 2 has no obvious transverse cracks on the surface, but has low microhardness, which is 700HV. 0.2 , wear resistance is poor.

[0040] Comparative Example 3

[0041] The powder cored wire consists of a 430 stainless steel strip and flux, which is filled in the strip. The percentage of the powder core component in the overall wire mass is as follows: The steel strip is rolled into a U-shaped groove, the powder is mixed and dried and then added, and the welding wire is obtained by rolling and drawing to reduce the diameter, and the welding wire diameter is 1.6mm;

[0042] The cladding layer prepared by the powder-cored welding 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 weld formability is poor.

[0043] The present invention refines the cladding layer structure by adding elements such as Nb and Ti to the flux core, and forms an MC-type carbide hard phase. At the same time, an appropriate amount of B element is added to increase the hardness of the cladding layer, and an arc stabilizer is added to improve the formability of the cladding layer. The prepared cladding layer has high hardness, high wear resistance, and controllable cracks. The flux-cored welding wire of the present invention has good welding process performance, obvious alloy structure refinement, uniform surface hardness of the cladding layer, an average hardness in the range of 59 to 62HRC, and good wear resistance. The welding wire can be used for the remanufacturing and repair of engineering equipment in the mining, coal, excavation and other industries, and the prepared cladding layer can withstand lighter impact loads; it can also be used for the remanufacturing and repair of small components and thin-walled components.

Claims

1. A high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire, characterized by: The welding wire is made of a steel strip as an outer sheath and a powder coating inside. The weight percentage of the powder components in the welding wire is as follows: 1-4% ferroboron, 5-8% ferroniobium, 3-5% ferrotitanium, 3-5% graphite, 7-14% metallic chromium, 1-2% ferrosilicon, 1-1.5% electrolytic manganese, 1-3% calcium fluoride, 1-2% aluminum oxide, and the balance is reduced iron powder. The powder accounts for 25-30% of the total weight of the powder-cored welding wire.

2. The high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire according to claim 1, characterized in that: The welding wire surface is 430 cold-rolled stainless steel strip with a width of 11 mm and a thickness of 0.3 mm.

3. The high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire according to claim 1, characterized in that: The powders in the powder core include electrolytic manganese, ferrosilicon, metallic chromium powder, high carbon ferrochromium, ferroniobium, ferrotitanium and ferroboron, and the particle size of each raw material in the powder is 60-100 meshes.

4. The high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire according to claim 1, characterized in that: The prepared welding wire passes through a wire drawing die, is drawn and reduced in diameter step by step, and finally the diameter of the welding wire reaches 1.2 to 1.6 mm.

5. The high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire according to claim 1, characterized in that: Adding calcium fluoride, aluminum oxide and other powders to the powder can make the surface of the cladding layer have good formability, no pores and little spatter. Within 3 to 4 layers of cladding, only a few micro cracks will appear in the cladding layer.

6. The high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire according to claim 1, characterized in that: The cladding layer is in a hypereutectic state, and the cladding layer structure is optimized by elements such as Nb, Ti, and B, and the cladding layer grains are refined, so that the cladding layer prepared by the welding wire has a Rockwell hardness greater than 59HRC and a Vickers hardness greater than 900HV. 0.2 , its relative wear resistance is 25 to 45 times that of Q345 steel.

7. The high-hardness, super-wear-resistant, crack-controlled cladding powder-cored welding wire according to claim 1, characterized in that: This welding wire can be used for surface strengthening and remanufacturing and repair of wear-resistant parts in mining, coal, and cement engineering machinery and equipment, and the prepared cladding layer can withstand lighter impact loads.

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