Repair process for scrapped guide and guard piece

Abstract

The invention discloses a scrapped guide part repair process, and relates to the technical field of guide parts, and the scrapped guide part repair process comprises the following steps: carrying out damage assessment in advance: detecting internal cracks of a guide part by using an ultrasonic flaw detector, determining the depth and the expansion direction of the cracks, and obtaining surface topography data of the guide part by using a three-dimensional laser scanner; and comparing with an original design model, quantifying the abrasion loss and the structural deformation, and determining the damage type of the scrapped guide and guard piece according to a detection result. The contradiction that wear resistance and toughness of a traditional single material cannot be achieved at the same time is broken through through the layered design of the gradient functional material, the bottom layer and the base material form strong metallurgical bonding to guarantee structural stability, the middle layer relieves interface stress concentration, and the surface layer endows the wear resistance under extreme working conditions through the high-hardness wear-resistant phase; and a repaired part can resist friction impact in high-temperature rolling and can also meet the toughness requirement under alternating loads.

Description

Technical Field

[0001] This invention relates to the field of guide component technology, and more specifically, to a repair process for scrapped guide components. Background Technology

[0002] As a core guiding component in steel rolling production, the performance of guide components directly determines rolling accuracy and production stability. Under extreme conditions of high temperature (500-1000℃), high friction, and alternating loads, the surface of guide components is prone to wear and cracks, and dimensional accuracy gradually deteriorates. Approximately 50% of rolling accidents and 60% of scrap rates are directly related to guide component failure. Traditional repair processes mostly rely on single-material welding or machining, which presents significant technical bottlenecks: for example, when using ordinary welding rods to repair cracks, uneven heat input can easily lead to porosity and slag inclusions, resulting in insufficient bonding strength between the repair layer and the substrate, with a secondary failure risk as high as 40%; for worn parts, simply restoring dimensions through turning without optimizing material properties for wear resistance requirements results in a repaired service life of only 30-50% of that of a new part, and frequent replacements actually increase production costs.

[0003] As steel rolling technology upgrades towards higher speeds and greater intelligence, the operating requirements for guide components are further increasing. For example, the rolling speed of high-speed wire rod mills has exceeded 120 m / s, requiring guide components to withstand higher instantaneous impact forces and frictional heat. The hardness and wear resistance of traditional repair materials can no longer meet these demands. Simultaneously, the industry's requirements for green manufacturing and resource recycling are becoming increasingly stringent. Directly discarding alloying elements such as Cr and Mo contained in scrapped guide components not only wastes metal resources but also exacerbates environmental pollution. While laser cladding and polymer composite material repair have been attempted in existing technologies, technological limitations exist: laser cladding often uses single alloy materials, making it difficult to balance wear resistance and toughness; while polymer materials can fill microcracks, their high-temperature resistance is insufficient, softening easily above 150°C, making them unsuitable for the high-temperature environment of steel rolling.

[0004] Therefore, there is an urgent need to build a repair system that integrates high-performance materials and composite processes to achieve long-life and low-cost remanufacturing of guide components.

[0005] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0006] In view of the problems in related technologies, this invention proposes a repair process for scrapped guide components to overcome the aforementioned technical problems existing in the existing related technologies.

[0007] The technical solution of this invention is implemented as follows:

[0008] A repair process for scrapped guide components includes the following steps:

[0009] Preliminary damage assessment includes: using an ultrasonic flaw detector to detect internal cracks in the guide component, determining the crack depth and propagation direction, and using a three-dimensional laser scanner to acquire surface morphology data of the guide component, comparing it with the original design model, quantifying the wear and structural deformation, and determining the damage type of the scrapped guide component based on the test results. The damage types include: minor damage, moderate damage, and severe damage, and structural deformation > 0.5 mm is considered irreparable.

[0010] Surface pretreatment is performed, including sandblasting to remove the surface oxide layer and oil stains, and grinding the small cracked areas until the cracks disappear;

[0011] Composite repair is carried out, and high-performance materials are selected for repair according to the type of damage. These include: for minor damage, nano-reinforced polymer composite materials are used for repair; for moderate damage, laser cladding is used as a base layer and surface pits are filled with nano-reinforced polymer composite materials for repair; for severe damage, graded functional materials are used for laser cladding.

[0012] Perform dimensional calibration, process the repaired guide components, and calibrate the dimensional accuracy and surface roughness;

[0013] To enhance performance, the metal repair area is subjected to high-frequency quenching treatment to achieve the preset surface hardness.

[0014] The ultrasonic testing frequency is 2-5MHz, and the accuracy of the three-dimensional scanning technology is ±0.01mm.

[0015] The sandblasting process involves sand particles with a diameter of 0.5-1.2 mm, a pressure of 0.4-0.6 MPa, and a surface roughness of Ra1.6-Ra3.2 after grinding.

[0016] The repair method using nano-reinforced polymer composite material includes the following steps: preparing nano-reinforced polymer composite material, uniformly applying the composite material to the damaged area with a thickness of 0.3-0.5 mm, curing it at 80-100℃ for 2-3 hours using an infrared heating plate, and then sanding it smooth with 400-600 grit sandpaper.

[0017] The nano-reinforced polymer composite material comprises, by raw material composition: 60%-70% epoxy resin matrix, 10%-15% silicon carbide nanoparticles and 20%-25% curing agent, wherein the particle size of the silicon carbide nanoparticles is 50nm-100nm.

[0018] The method of using laser cladding for priming and filling and repairing surface pits with nano-reinforced polymer composite material includes the following steps:

[0019] First, laser cladding is performed on the cracked area. Nickel-based alloy powder is selected, the cladding power is 1.5kW, the scanning speed is 8mm / s, and the cladding layer thickness is 0.3-0.5mm. The raw material composition of the nickel-based alloy powder includes at least 18%Cr and 6%Mo.

[0020] The surface pits are then filled with nano-reinforced polymer composite material, and the entire surface is polished after curing.

[0021] The laser cladding using graded functional materials involves dividing the repair layer into three layers: a bottom layer of low-alloy steel, a middle layer of nickel-based alloy, and a top layer of cobalt-based alloy containing 20% ​​WC. The cladding power is 1.5-2.5kW, and the scanning speed is 5-10mm / s.

[0022] The high-frequency quenching process includes: heating at 850-950℃ and holding for 15-20 minutes when the thickness is ≤5mm or holding for 20-30 minutes when the thickness is >5mm, and cooling by water quenching.

[0023] The beneficial effects of this invention are:

[0024] This invention overcomes the inherent trade-off between wear resistance and toughness in traditional single-material systems through a layered design of graded functional materials. The bottom layer forms a strong metallurgical bond with the substrate to ensure structural stability, the middle layer alleviates interfacial stress concentration, and the surface layer, with its high-hardness wear-resistant phase, provides wear resistance under extreme conditions. This allows the repaired component to withstand the frictional impacts of high-temperature rolling while also meeting the toughness requirements under alternating loads. Simultaneously, the introduction of nano-reinforced polymer materials enables precise filling of shallow micro-damage. Combined with automated process parameter control, this avoids the performance fluctuations associated with traditional manual repairs, significantly improving the consistency and reliability of repair quality and meeting the high-precision, long-life requirements of high-speed rolling for guide components. Furthermore, the differentiated repair strategy maximizes the resource utilization of scrapped guide components, reducing the raw material mining and smelting processes required for new component production, lowering carbon emissions and energy consumption in the industrial chain, and supporting efficiency improvements in mass production scenarios. This significantly shortens the repair cycle and reduces overall costs, creating substantial economic benefits for enterprises. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic flowchart of a repair process for scrapped guide components according to an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0028] According to an embodiment of the present invention, a repair process for scrapped guide components is provided.

[0029] like Figure 1 As shown, the repair process for scrapped guide components according to an embodiment of the present invention includes the following steps:

[0030] Step S1 involves preliminary damage assessment, including: using an ultrasonic flaw detector to detect internal cracks in the guide component, determining the crack depth and propagation direction, and using a 3D laser scanner to acquire surface morphology data of the guide component. This data is then compared with the original design model to quantify wear and structural deformation. The damage type is then classified based on the test results, as detailed below:

[0031] Minor damage is defined as: crack depth < 0.3 mm, wear < 0.1 mm, and structural deformation ≤ 0.3 mm.

[0032] Among them, moderate damage is expressed as: 0.3mm ≤ crack depth ≤ 0.5mm, 0.1mm ≤ wear amount < 0.3mm, and structural deformation amount 0.3-0.5mm;

[0033] Severe damage is defined as: crack depth > 0.5 mm, wear ≥ 0.3 mm, and structural deformation ≤ 0.5 mm.

[0034] Among them, "unrepairable" is indicated by: structural deformation > 0.5 mm, or cracks penetrating the component.

[0035] Step S2 involves surface pretreatment, including using quartz sand with a diameter of 0.5-1.2 mm to sandblast the surface of the guide component under a pressure of 0.4-0.6 MPa to remove oxide layer, oil and rust, achieving a surface cleanliness of Sa2.5 level, and wiping the repaired area with alcohol or acetone to remove residual impurities.

[0036] This also includes: for minor surface cracks, use an angle grinder to grind along the crack direction until the crack is completely eliminated, and control the surface roughness to Ra1.6-Ra3.2 after grinding;

[0037] Step S3 involves performing composite repair based on the classification of the test results, which includes the following steps:

[0038] In the calibration of the guide component, which is slightly damaged, a nano-reinforced polymer composite material is prepared and uniformly coated on the damaged area with a thickness of 0.3-0.5 mm. The material is then cured at 80-100℃ for 2-3 hours using an infrared heating plate. After curing, the surface is smoothed with sandpaper of 400-600 grit.

[0039] The formulation of the nano-reinforced polymer composite material includes: 60%-70% epoxy resin matrix, 10%-15% silicon carbide nanoparticles with a particle size of 50nm-100nm, and 20%-25% curing agent. During preparation, the silicon carbide nanoparticles must be ultrasonically dispersed at a power of 300-500W for 30-60 minutes to ensure uniformity.

[0040] In this technical solution, the material has a compressive strength of ≥80MPa and a wear resistance that is 40% higher than that of ordinary epoxy resin.

[0041] Among them, the calibration guide component is moderately damaged. First, the cracked area is laser cladding as a base layer. Nickel-based alloy powder containing 18% Cr and 6% Mo is selected. The cladding power is 1.5kW, the scanning speed is 8mm / s, and the cladding layer thickness is 0.3-0.5mm. Then, the surface pits are filled with nano-reinforced polymer composite material, and the whole thing is polished after curing.

[0042] Among them, the calibration guide component was severely damaged, and laser cladding with graded functional materials was used to divide the repair layer into three layers, as follows:

[0043] The substrate bonding layer is the bottom layer, which is made of low alloy steel powder. The cladding power is 1.5kW and the scanning speed is 8-10mm / s to ensure metallurgical bonding with the substrate. The dilution rate is ≤5%. The low alloy steel powder includes 85%Fe, 10%Ni and 5%Cr.

[0044] The intermediate layer is made of nickel-based alloy, with a cladding power of 2.0kW and a scanning speed of 6-8mm / s, to relieve interfacial stress. The nickel-based alloy consists of 60% Ni, 20% Cr and 5% Mo.

[0045] The surface layer is made of a cobalt-based alloy containing 20% ​​WC particles, with a cladding power of 2.5kW and a scanning speed of 5-6mm / s, forming a wear-resistant surface layer with a hardness ≥HRC60 and a thickness of 0.5-1.5mm.

[0046] In addition, when applying this material, for parts with out-of-tolerance dimensional wear, the wear layer is first removed by machining on a lathe, and then the dimensions are restored by cladding with the aforementioned gradient material.

[0047] Step S4: Perform dimensional calibration and use a grinding machine to process the repaired guide component. The key dimensions are controlled according to the design drawings, with a tolerance grade of IT6-IT7.

[0048] This also includes surface roughness treatment, including: non-mating surfaces Ra1.6-Ra3.2, mating surfaces Ra0.8-Ra1.6, and wear-resistant working surfaces achieving Ra0.4-Ra0.8 through ultra-precision grinding.

[0049] Step S5 involves performing high-frequency quenching on the metal repair area, including: using a 100-200kHz high-frequency induction coil to heat the roller surface to 850-950℃, holding the temperature for a time that matches the thickness, and then water quenching to room temperature.

[0050] The heat preservation time is matched with the thickness, including: 15-20 minutes when the thickness is ≤5mm, and 20-30 minutes when the thickness is >5mm;

[0051] In addition, when applying the polymer material, the repaired area needs to be covered with high-temperature resistant heat insulation material to avoid high-temperature damage; after treatment, the surface hardness reaches HB30-35, and the core hardness is ≤HB25, forming a gradient structure of "hard surface - tough core", which improves the impact resistance by 30%.

[0052] Step S6 also includes quality inspection, as detailed below:

[0053] Mechanical property tests were conducted, with Rockwell hardness tester used to detect surface hardness and Vickers hardness tester used to detect hardness distribution in gradient layers; tensile testing machine was used to test the bonding strength of the repair layer.

[0054] Perform dimensional accuracy checks, using a coordinate measuring machine to inspect key dimensions to ensure they meet the drawing requirements;

[0055] Non-destructive testing is performed, including ultrasonic testing of the repaired area to eliminate internal porosity, cracks, and penetrants, and to eliminate surface micro-defects.

[0056] Using the above solution, taking the repair of a severely worn guide roll of a rolling mill as an example, the implementation steps are as follows:

[0057] The damage was assessed, with a surface crack depth of 0.8 mm, guide surface wear of 0.5 mm, and structural deformation of 0.3 mm.

[0058] Three-dimensional scanning confirms the wear area, and ultrasonic testing locates the crack.

[0059] After sandblasting, the 0.5mm wear layer is removed by turning;

[0060] Laser cladding using graded functional materials is employed, including: a base layer of low-alloy steel with a power of 1.5kW and a speed of 10mm / s; a middle layer of nickel-based alloy with a power of 2.0kW and a speed of 7mm / s; and a surface layer of cobalt-based alloy containing WC with a power of 2.5kW and a speed of 5mm / s, for a total repair thickness of 1.0mm.

[0061] Precision grinding to the design dimensions, with a surface roughness of Ra0.8;

[0062] Perform high-frequency quenching at 900℃ for 25 minutes, followed by water quenching.

[0063] The surface hardness was HRC62, the bonding strength was 350MPa, the dimensional tolerance was IT6, and the service life after installation and trial use reached 85% of that of a new part.

[0064] Furthermore, taking the repair of a guide bracket made of ZG35CrNiMo with minor cracks as an example, the specific implementation is as follows:

[0065] Damage inspection revealed multiple deep cracks of 0.2-0.3mm on the surface, with no obvious wear.

[0066] After grinding the cracks, a nano-reinforced epoxy resin composite material was used, in which silicon carbide nanoparticles were ultrasonically dispersed at 500W for 60 minutes and then filled.

[0067] After curing at 80℃ for 3 hours, the surface is polished smooth, and the polymer area is covered before the metal matrix is ​​locally quenched.

[0068] Testing revealed that the repaired area had a hardness of HB28, no surface defects, and met the usage requirements.

[0069] In summary, by employing the above-described technical solution of the present invention, the following effects can be achieved:

[0070] This invention overcomes the inherent trade-off between wear resistance and toughness in traditional single-material systems through a layered design of graded functional materials. The bottom layer forms a strong metallurgical bond with the substrate to ensure structural stability, the middle layer alleviates interfacial stress concentration, and the surface layer, with its high-hardness wear-resistant phase, provides wear resistance under extreme conditions. This allows the repaired component to withstand the frictional impacts of high-temperature rolling while also meeting the toughness requirements under alternating loads. Simultaneously, the introduction of nano-reinforced polymer materials enables precise filling of shallow micro-damage. Combined with automated process parameter control, this avoids the performance fluctuations associated with traditional manual repairs, significantly improving the consistency and reliability of repair quality and meeting the high-precision, long-life requirements of high-speed rolling for guide components. Furthermore, the differentiated repair strategy maximizes the resource utilization of scrapped guide components, reducing the raw material mining and smelting processes required for new component production, lowering carbon emissions and energy consumption in the industrial chain, and supporting efficiency improvements in mass production scenarios. This significantly shortens the repair cycle and reduces overall costs, creating substantial economic benefits for enterprises.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Those skilled in the art, upon considering the disclosure in the specification and embodiments, will readily conceive of other embodiments of this disclosure. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0072] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A repair process for scrapped guide components, characterized in that, Includes the following steps: Preliminary damage assessment includes: using an ultrasonic flaw detector to detect internal cracks in the guide component, determining the crack depth and propagation direction, and using a three-dimensional laser scanner to acquire surface morphology data of the guide component, comparing it with the original design model, quantifying the wear and structural deformation, and determining the damage type of the scrapped guide component based on the test results. The damage types include: minor damage, moderate damage, and severe damage, and structural deformation > 0.5 mm is considered irreparable. Surface pretreatment is performed, including sandblasting to remove the surface oxide layer and oil stains, and grinding the small cracked areas until the cracks disappear; Composite repair is carried out, and high-performance materials are selected for repair according to the type of damage. These include: for minor damage, nano-reinforced polymer composite materials are used for repair; for moderate damage, laser cladding is used as a base layer and surface pits are filled with nano-reinforced polymer composite materials for repair; for severe damage, graded functional materials are used for laser cladding. Perform dimensional calibration, process the repaired guide components, and calibrate the dimensional accuracy and surface roughness; To enhance performance, the metal repair area is subjected to high-frequency quenching treatment to achieve the preset surface hardness.

2. The repair process for scrapped guide components according to claim 1, characterized in that, The ultrasonic testing frequency is 2-5MHz, and the accuracy of the three-dimensional scanning technology is ±0.01mm.

3. The repair process for scrapped guide components according to claim 1, characterized in that, The sandblasting process uses sand particles with a diameter of 0.5-1.2 mm and a pressure of 0.4-0.6 MPa. The surface roughness after grinding is controlled to be Ra1.6-Ra3.

2.

4. The repair process for scrapped guide components according to claim 1, characterized in that, The repair using nano-reinforced polymer composite material includes the following steps: preparing nano-reinforced polymer composite material, uniformly applying the composite material to the damaged area with a thickness of 0.3-0.5 mm, curing it at 80-100℃ for 2-3 hours using an infrared heating plate, and then sanding it smooth with sandpaper at 400-600 grit.

5. The repair process for scrapped guide components according to claim 4, characterized in that, The nano-reinforced polymer composite material comprises, by raw material composition: 60%-70% epoxy resin matrix, 10%-15% silicon carbide nanoparticles and 20%-25% curing agent, wherein the particle size of the silicon carbide nanoparticles is 50nm-100nm.

6. The repair process for scrapped guide components according to claim 5, characterized in that, The method of laser cladding for priming and filling and repairing surface pits with nano-reinforced polymer composite material includes the following steps: First, laser cladding is performed on the cracked area. Nickel-based alloy powder is selected, the cladding power is 1.5kW, the scanning speed is 8mm / s, and the cladding layer thickness is 0.3-0.5mm. The raw material composition of the nickel-based alloy powder includes at least 18%Cr and 6%Mo. The surface pits are then filled with nano-reinforced polymer composite material, and the entire surface is polished after curing.

7. The repair process for scrapped guide components according to claim 6, characterized in that, The laser cladding using graded functional materials involves dividing the repair layer into three layers: a bottom layer of low alloy steel, a middle layer of nickel-based alloy, and a top layer of cobalt-based alloy containing 20% ​​WC. The cladding power is 1.5-2.5kW, and the scanning speed is 5-10mm / s.

8. The repair process for scrapped guide components according to claim 1, characterized in that, The high-frequency quenching process includes: heating at 850-950℃ and holding for 15-20 minutes when the thickness is ≤5mm or holding for 20-30 minutes when the thickness is >5mm, and cooling by water quenching.

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