Furnace shell repairing method based on additive manufacturing

Abstract

The invention relates to the technical field of furnace shell repair, in particular to a furnace shell repair method based on additive manufacturing, which effectively solves the problem that corrosion pits and cracks are easy to generate on the inner walls of blast furnaces and hot blast stoves under the working environment of high-concentration S2 <-> and CL <->. Constructed blast furnace and hot blast stove shells are reinforced and corrected by utilizing an additive manufacturing technology, so that the performance of the blast furnace and hot blast stove shells is enhanced, and the production efficiency is improved; the technical method for maintaining the furnace shells of the blast furnace and the hot blast stove is widened, the situation of large-area welding of new repair welding plates after cutting in a traditional maintaining method is avoided, and the possibility of forming welding defects is reduced; on the basis of the additive manufacturing technology, the blast furnace and hot blast stove shell can be repaired as old as new, and a layer of deposited metal with good corrosion resistance is further cladded on the surface of the repaired blast furnace and hot blast stove shell, so that the corrosion resistance of the blast furnace and hot blast stove shell is enhanced; and the existing weather-proof welding wire is used for welding, so that the economical efficiency of the method is improved.

Description

Technical Field

[0001] The invention relates to the technical field of furnace shell repair, and in particular to a furnace shell repair method based on additive manufacturing. Background Art

[0002] Blast furnaces and hot blast furnaces are important equipment in the long-process ironmaking field. Due to the long-term high temperature and high pressure harsh working conditions, and due to long-term contact with sulfur-rich 2- and CL - The high-temperature hot air can easily destroy the stable anti-corrosion layer on the surface of the furnace shell due to pitting corrosion and form corrosion pits. The corrosion pits, as weak points, produce stress concentration. Small cracks are easily generated around the corrosion pits and form larger cracks by extending along the crystal and through the crystal, affecting the overall performance of the blast furnace and hot blast stove, and eventually causing damage and leakage, affecting production safety and efficiency. In view of the damage and leakage problems of the blast furnace and hot blast stove shells in the ironmaking field, the use of effective repair technology can improve the service life and safety of blast furnaces and hot blast stoves. The traditional repair method is to cut the damaged area and then re-weld it. This method is time-consuming and labor-intensive, and if the welding area is too large, it will easily form new weak points due to welding defects such as undercuts and pores, affecting the performance of the furnace shell. Therefore, it is particularly important to develop an efficient and reliable furnace shell repair technology. Summary of the invention

[0003] The present invention aims to solve the above problems and thus provide a furnace shell repair method based on additive manufacturing.

[0004] The present invention solves the above-mentioned problem by adopting the following technical solution:

[0005] A furnace shell repair method based on additive manufacturing is carried out in the following steps:

[0006] Step 1: First, clean the surface of the blast furnace and hot blast furnace, remove dust and rust until the base metal is seen, and measure the width and length of the cracks, and record the direction of the cracks;

[0007] Step 2: Analyze the crack width and length and determine the milling width;

[0008] Step 3: Select welding materials and welding parameters; According to the results of multiple tests, XY-ER80QNH weather-resistant welding wire is selected for welding, and the welding parameters of 230A, 22.6V, and 0.5m / min are used for additive manufacturing. The cladding metal has the best corrosion resistance and mechanical properties;

[0009] Step 4: Mill the cracks and perform secondary cleaning after milling;

[0010] Step 5: Additive manufacturing is performed after cleaning is completed; after the additive manufacturing of the crack area is completed, additive manufacturing is continued on both sides to perform single-layer multi-pass additive manufacturing of the pitting pit area;

[0011] Step 6: Wait for complete cooling before polishing the surface.

[0012] Furthermore, in step 2, the milling width should be between 5-8 mm and the depth should be less than 10 mm.

[0013] Furthermore, in step 4, the crack area is milled into a trapezoidal area or a V-shaped area for additive manufacturing.

[0014] Furthermore, in step five, single-layer multi-pass welding is performed when the milling depth is less than 3 mm, double-layer multi-pass welding is performed when the depth is less than 5 mm, and multi-layer multi-pass welding is performed when the depth is less than 10 mm.

[0015] Compared with the prior art, the present invention adopting the above technical solution has the following outstanding features:

[0016] The method of the present invention effectively solves the problem of high concentration S in the inner wall of blast furnace and hot blast furnace. 2- and CL - In the working environment, pits and cracks are prone to occur. The additive manufacturing technology is used to strengthen and correct the shells of the blast furnace and hot blast furnace that have been constructed, which enhances the performance of the shells and improves the production efficiency; the technical methods for repairing the shells of blast furnaces and hot blast furnaces are broadened to avoid the large-area welding of new plates after cutting in the traditional repair methods, reducing the possibility of welding defects; based on the additive manufacturing technology, the blast furnace and hot blast furnace shells are not only repaired to the state of being like new, but also a layer of welded metal with good corrosion resistance is melted on the surface of the repaired blast furnace and hot blast furnace shells, which enhances the corrosion resistance of the blast furnace and hot blast furnace shells; the existing weather-resistant welding wire is used for welding to improve the economy of this method. DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with embodiments, the purpose of which is only to provide a better understanding of the content of the present invention. Therefore, the examples given do not limit the protection scope of the present invention.

[0018] A furnace shell repair method based on additive manufacturing is carried out in the following steps:

[0019] Step 1: First, clean the surface of the blast furnace and hot blast furnace, remove dust and rust until the base metal is seen, and measure the width and length of the cracks, and record the direction of the cracks;

[0020] Step 2: Analyze the crack width and length and determine the milling width;

[0021] Step 3: Select welding materials and welding parameters; According to the results of multiple tests, XY-ER80QNH weather-resistant welding wire is selected for welding, and the welding parameters of 230A, 22.6V, and 0.5m / min are used for additive manufacturing. The cladding metal has the best corrosion resistance and mechanical properties;

[0022] Step 4: Mill the cracks and perform secondary cleaning after milling;

[0023] Step 5: Additive manufacturing is performed after cleaning is completed; after the additive manufacturing of the crack area is completed, additive manufacturing is continued on both sides to perform single-layer multi-pass additive manufacturing of the pitting pit area;

[0024] Step 6: Wait for the surface to be polished after it is completely cooled; air cool for at least eight hours, and we will get the blast furnace and hot blast furnace shell with good corrosion resistance on the working surface.

[0025] Furthermore, in step 2, the milling width should be between 5-8mm and the depth should be less than 10mm; the shell of blast furnace and hot blast furnace is usually 20mm thick, and the crack depth generally does not exceed 1 / 3, which is about 7mm. When cleaning the base layer, more metal can be milled appropriately to reach 8-9mm.

[0026] Furthermore, in step 4, the crack area is milled into a trapezoidal area or a V-shaped area for additive manufacturing.

[0027] Furthermore, in step five, single-layer multi-pass welding is performed when the milling depth is less than 3 mm, double-layer multi-pass welding is performed when the depth is less than 5 mm, and multi-layer multi-pass welding is performed when the depth is less than 10 mm; for multi-layer multi-pass welding, the number of welding layers should not be too many. Too many welding layers and excessive heat input will affect the material properties of the heat-affected zone. Before additive manufacturing, a flame spray gun is used to preheat the base metal before welding. The preheating temperature is between 200°C and 220°C, and the inter-pass temperature should not be lower than 150°C during the process.

[0028] Table 1 Chemical composition of XY-ER80QNH weather-resistant welding wire

[0029]

[0030] Table 2 Mechanical properties of deposited metal of XY-ER80QNH weather-resistant welding wire

[0031]

[0032] The weathering index of welding wire is also called the atmospheric resistance index, which is calculated according to the provisions of the American ASTM G101-04 standard. The calculation formula of the weathering index is as follows:

[0033] I=26.01ω(Cu)+3.88ω(Ni)+1.20ω(Cr)+1.49ω(Si)+17.28ω(P)-7.29ω(Cu)ω(Ni)-9.10ω(Ni)ω(P)-33.39[ω(Cu)]2=12.34

[0034] When I≥6, it indicates good atmospheric corrosion resistance.

[0035] Through calculation and multiple experimental comparisons using different welding wires, it was found that because XY-ER80QNH weather-resistant welding wire contains Cu and Ni elements, it has a weather resistance index of up to 12.34, which is an excellent welding wire with a weather resistance index. Therefore, XY-ER80QNH weather-resistant welding wire was selected as the welding material.

[0036] The method of the present invention effectively solves the problem of high concentration S in the inner wall of blast furnace and hot blast furnace. 2- and CL - In the working environment, pits and cracks are prone to occur. The additive manufacturing technology is used to strengthen and correct the shells of the blast furnace and hot blast furnace that have been constructed, which enhances the performance of the shells and improves the production efficiency; the technical methods for repairing the shells of blast furnaces and hot blast furnaces are broadened to avoid the large-area welding of new plates after cutting in the traditional repair methods, reducing the possibility of welding defects; based on the additive manufacturing technology, the blast furnace and hot blast furnace shells are not only repaired to the state of being like new, but also a layer of welded metal with good corrosion resistance is melted on the surface of the repaired blast furnace and hot blast furnace shells, which enhances the corrosion resistance of the blast furnace and hot blast furnace shells; the existing weather-resistant welding wire is used for welding to improve the economy of this method.

[0037] The above description is only a preferred feasible embodiment of the present invention, and does not limit the scope of rights of the present invention. All equivalent changes made using the contents of the present invention specification are included in the scope of rights of the present invention.

Claims

1. A furnace shell repair method based on additive manufacturing, characterized in that: Follow these steps: Step 1: First, clean the surface of the blast furnace and hot blast furnace, remove dust and rust until the base metal is seen, and measure the width and length of the cracks, and record the direction of the cracks; Step 2: Analyze the crack width and length and determine the milling width; Step 3: Select welding materials and welding parameters; According to the results of multiple tests, XY-ER80QNH weather-resistant welding wire is selected for welding, and the welding parameters of 230A, 22.6V, and 0.5m / min are used for additive manufacturing. The cladding metal has the best corrosion resistance and mechanical properties; Step 4: Mill the cracks and perform secondary cleaning after milling; Step 5: Additive manufacturing is performed after cleaning is completed; after the additive manufacturing of the crack area is completed, additive manufacturing is continued on both sides to perform single-layer multi-pass additive manufacturing of the pitting pit area; Step 6: Wait for complete cooling before polishing the surface.

2. The furnace shell repair method based on additive manufacturing according to claim 1, characterized in that: In step 2, the milling width should be between 5-8mm and the depth should be less than 10mm.

3. The furnace shell repair method based on additive manufacturing according to claim 1, characterized in that: In step 4, the crack area is milled into a trapezoidal area or a V-shaped area for additive manufacturing.

4. The furnace shell repair method based on additive manufacturing according to claim 1, characterized in that: In step 5, single-layer multi-pass welding is performed when the milling depth is less than 3 mm, double-layer multi-pass welding is performed when the depth is less than 5 mm, and multi-layer multi-pass welding is performed when the depth is less than 10 mm.

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