Method for improving segregation of spring steel continuous casting billet to reduce drawing and bending fractures

Abstract

The invention relates to the technical field of spring steel, and discloses a method for reducing drawing and bending fractures by segregation of a spring steel continuous casting billet, which comprises the following specific steps: S1, detecting segregation of the continuous casting billet, S2, optimizing continuous casting process parameters, S3, strengthening refining treatment and S4, monitoring quality and continuously improving. According to the method for improving segregation of the spring steel continuous casting billet, the segregation phenomenon of the core of the continuous casting billet can be effectively reduced, for example, continuous casting process parameters are optimized, refining treatment is enhanced, molten steel components can be more uniform, segregation belts, cavities and microcracks are reduced, and therefore the quality of the spring steel is improved; the fracture risk in the drawing and bending process is reduced, spring steel products with higher quality are produced, and the requirement of the market for high-quality spring steel is met.

Description

Technical Field

[0001] The invention relates to the technical field of spring steel, in particular to a method for improving the segregation of spring steel continuous casting billets to reduce drawing and bending fractures. Background Art

[0002] In the field of spring steel production, the problem of drawing and bending fracture seriously affects product quality and production efficiency. The case reported by Hubei Juxin Industry and Trade Co., Ltd. is typical. The specific specifications of spring steel used by it have a large number of fractures during drawing and bending. After analyzing the relevant samples, it was found that there were many defects in the fracture, such as two pairs of core-pulling fractures that could be spliced, and 6 bending fractures. Through stereomicroscope and metallographic analysis, it can be seen that there are obvious voids, segregation bands and microcracks in the core of the fracture, and the metallographic structure is troostite + pearlite + a small amount of ferrite. Comprehensive analysis shows that the serious segregation of the wire rod core is the main cause of drawing core-pulling fracture and bending fracture, and the segregation of the wire rod core is seriously related to the segregation of the continuous casting billet. This problem not only causes material waste and increases production costs, but may also affect the performance and safety of downstream products, and needs to be solved urgently. Summary of the invention

[0003] 1. Technical issues to be resolved In view of the shortcomings of the prior art, the present invention provides a method for improving the segregation of spring steel continuous casting billets to reduce drawing and bending fractures, which has the advantages of improving product quality and reducing production costs, and solves the problem that the serious segregation of the wire rod core is the main cause of drawing core fracture and bending fracture, and the segregation of the wire rod core is seriously related to the segregation of the continuous casting billet. This problem not only causes material waste and increases production costs, but also may affect the performance and safety of downstream products.

[0004] (II) Technical solution In order to achieve the above-mentioned purpose of improving product quality and reducing production costs, the present invention provides the following technical solution: a method for improving the segregation of spring steel continuous casting billets to reduce drawing and bending fractures, comprising the following specific method steps: S1 continuous casting billet segregation detection: Sample selection: Regularly select representative samples from the spring steel billets produced by continuous casting. For spring steel with a specification of 6.5 mm, focus on the continuous casting billets corresponding to the batches that have problems after drawing; Detection of fracture and metallographic structure: Perform fracture analysis on the sample, observe the macroscopic morphology of the fracture, and check whether there are similar core-pulling fracture and bending fracture; S2 optimizes continuous casting process parameters: Adjust the cooling rate: To solve the problem of continuous casting billet segregation, appropriately reduce the cooling rate during the continuous casting process. Rapid cooling may cause the components to not diffuse evenly in time, aggravating the segregation. Control the billet drawing speed: According to the adjustment of cooling speed, reasonably control the billet drawing speed. Too fast billet drawing speed will cause uneven solidification of molten steel and aggravate segregation. After the cooling rate is reduced, the billet drawing speed should be reduced accordingly to ensure that the molten steel has a suitable solidification time in the crystallizer. The original billet drawing speed is [X] m / min. After adjusting the cooling rate, the billet drawing speed can be reduced to [X - 0.1] - [X -0.2] m / min. The optimal billet drawing speed is determined through actual production and testing to improve the segregation of continuous casting billets. S3 enhanced refining treatment: Increase refining time: During the steelmaking process, extend the refining time to make the composition of the molten steel more uniform; Optimize the use of refining agents: select more suitable refining agents, and optimize their usage and addition methods. According to the composition characteristics and segregation of spring steel, adjust the formula and addition amount of refining agents. For elements that are prone to segregation, increase the refining agent components that can promote their uniform distribution. S4 Quality Monitoring and Continuous Improvement: Establish a quality inspection system: During the production process, establish a complete quality inspection system and conduct regular inspections on continuous casting billets; Data analysis and process adjustment: Analyze the test data in detail. If it is found that the segregation problem still exists or new quality problems arise, adjust the continuous casting process parameters and refining treatment methods in time; Based on actual production data and test results, the entire production process is continuously optimized to continuously reduce the segregation of continuous casting billets, reduce the risk of spring steel breakage during drawing and bending, and ensure stable product quality.

[0005] Preferably, the detection of fracture and metallographic structure adopts metallographic analysis method, samples are taken from the cross section near the core-pulling fracture and the bending fracture, and the metallographic structure is observed under a microscope, with emphasis on detecting whether there are segregation bands, voids and microcracks defects. The voids, segregation bands and microcracks in the fracture core of the sample require further analysis of the segregation degree.

[0006] Preferably, the cooling rate is adjusted. If the original cooling rate is too fast, the cooling rate can be reduced by a certain percentage, such as 20% to 30%. The specific value needs to be adjusted according to the actual production situation and subsequent test results to ensure that the molten steel has more sufficient time for component diffusion during the solidification process and reduce segregation.

[0007] Preferably, the refining time may be increased appropriately by 10-15 minutes if the original refining time is short, so that various elements can be fully diffused and evenly distributed, thereby reducing component segregation.

[0008] Preferably, when using the optimization refining agent, the addition time and addition sequence of the refining agent are strictly controlled to ensure the refining effect and reduce the segregation degree of continuous casting billets.

[0009] Preferably, when establishing the quality inspection system, fracture analysis and metallographic inspection are carried out at regular intervals or after producing a certain number of continuous casting billets to monitor whether the segregation situation has been improved.

[0010] (III) Beneficial effects Compared with the prior art, the present invention provides a method for improving the segregation of spring steel continuous casting billets to reduce drawing and bending fractures, and has the following beneficial effects: 1. The method for improving the segregation of spring steel continuous casting billets to reduce drawing and bending fractures can improve the product quality: By implementing the method for improving the segregation of spring steel continuous casting billets, the segregation phenomenon in the core of the continuous casting billet can be effectively reduced. For example, by optimizing the continuous casting process parameters and strengthening the refining treatment, the composition of the molten steel can be made more uniform, reducing the occurrence of segregation bands, cavities and microcracks, thereby improving the quality of spring steel, reducing the fracture risk during drawing and bending, producing higher-quality spring steel products, and meeting the market demand for high-quality spring steel. Reduce production costs: Reducing drawing and bending fractures means reducing material waste caused by unqualified products, improving material utilization rate. At the same time, it reduces the rework, scrap costs caused by product quality problems, as well as potential customer complaints and claim costs in the future, and improves the economic benefits of the enterprise.

[0011] 2. The method for improving the segregation of spring steel continuous casting billets to reduce drawing and bending fractures can enhance the competitiveness of the enterprise: Stable product quality helps the enterprise establish a good brand image in the market, win the trust and word-of-mouth of customers. An enterprise that can produce high-quality spring steel products with a low defect rate has more advantages in the market competition, which is conducive to expanding the market share and enhancing the status and competitiveness of the enterprise in the industry. Promote the technological progress of the industry: The application and improvement of this method provide a useful reference for the spring steel production industry, prompting other enterprises to pay attention to and improve the segregation problem of continuous casting billets, promoting the technological progress of the whole industry in production processes and quality control, and promoting the healthy development of the spring steel industry. Specific implementation manners

[0012] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0013] The present invention provides a technical solution, specifically, a method for improving the segregation of continuous casting billets of spring steel to reduce drawing and bending fractures, including the following specific method steps: S1 Detection of segregation of continuous casting billets: Select samples: Regularly select representative samples from the spring steel billets produced by continuous casting. For spring steel with a specification of 6.5 mm, special attention should be paid to the continuous casting billets corresponding to the batches with problems after drawing; Detect fracture surfaces and metallographic structures: Conduct fracture surface analysis on the samples, observe the macroscopic morphology of the fracture surfaces, and check for the presence of similar core-pulling fracture surfaces and bending fracture surfaces; Among them, for detecting fracture surfaces and metallographic structures, a metallographic analysis method is used. Samples are taken from the cross-sections near the core-pulling fracture surfaces and bending fracture surfaces, and the metallographic structures are observed using a microscope. Special attention is paid to detecting the presence of segregation bands, cavities, and microcrack defects. For the problems of cavity cores, segregation bands, and microcracks existing in the samples, the degree of segregation needs to be further analyzed; S2 Optimize continuous casting process parameters: Adjust the cooling rate: For the problem of segregation of continuous casting billets, appropriately reduce the cooling rate during continuous casting. Rapid cooling may cause the components to not have enough time to diffuse evenly, exacerbating segregation; Among them, when adjusting the cooling rate, if the original cooling rate is relatively fast, the cooling rate can be tried to be reduced by a certain proportion, such as 20% - 30%. The specific value needs to be adjusted according to the actual production situation and subsequent detection results to ensure that the molten steel has more sufficient time for component diffusion during solidification, reducing segregation; Control the casting speed: According to the adjustment of the cooling rate, reasonably control the casting speed. Excessive casting speed will cause uneven solidification of the molten steel, aggravating segregation; After the cooling rate is reduced, the casting speed should be correspondingly reduced to ensure that the molten steel has an appropriate solidification time in the mold. The original casting speed is [X] m / min. After adjusting the cooling rate, the casting speed can be reduced to [X - 0.1] - [X - 0.2] m / min. Determine the optimal casting speed through actual production and detection to improve the segregation situation of continuous casting billets; S3 Strengthen refining treatment: Increase the refining time: During steelmaking, extend the refining time to make the components in the molten steel more uniform; Among them, when increasing the refining time, if the original refining time is relatively short, the refining time can be appropriately increased, such as increasing by 10 - 15 minutes, to allow various elements to fully diffuse and be evenly distributed, reducing component segregation; Optimizing the use of refining agents: Select more suitable refining agents and optimize their usage amounts and addition methods. According to the compositional characteristics and segregation conditions of spring steel, adjust the formula and addition amount of the refining agents. For elements prone to segregation, specifically increase the components of the refining agents that can promote their uniform distribution. At the same time, strictly control the addition time and addition sequence of the refining agents to ensure the refining effect and reduce the segregation degree of continuous casting billets. S4 Quality monitoring and continuous improvement: Establishing a quality inspection system: During the production process, establish a complete quality inspection system to regularly inspect the continuous casting billets. Among them, when establishing the quality inspection system, after a certain period of time or after producing a certain number of continuous casting billets, conduct fracture analysis and metallographic inspection to monitor whether the segregation situation has improved. Data analysis and process adjustment: Conduct a detailed analysis of the inspection data. If it is found that the segregation problem still exists or new quality problems occur, promptly adjust the continuous casting process parameters and refining treatment methods. Based on the actual production data and inspection results, continuously optimize the entire production process, continuously reduce the segregation of continuous casting billets, reduce the fracture risk of spring steel during drawing and bending processes, and ensure the stable quality of products.

[0014] Furthermore, this method improves product quality: By implementing the method to improve the segregation of spring steel continuous casting billets, it can effectively reduce the segregation phenomenon in the core of the continuous casting billets. For example, by optimizing the continuous casting process parameters and strengthening the refining treatment, the composition of the molten steel can be made more uniform, reducing the occurrence of segregation bands, voids, and microcracks, thereby improving the quality of spring steel, reducing the fracture risk during drawing and bending processes, producing higher-quality spring steel products, and meeting the market's demand for high-quality spring steel. Reducing production costs: Reducing drawing and bending fractures means reducing material waste caused by unqualified products, improving material utilization rates. At the same time, it reduces the rework, scrapping costs caused by product quality problems, as well as potential subsequent customer complaints and claim costs, improving the economic efficiency of the enterprise.

[0015] Furthermore, this method enhances the competitiveness of the enterprise: Stable product quality helps the enterprise establish a good brand image in the market, win the trust and word-of-mouth of customers. Enterprises that can produce high-quality spring steel products with low defect rates have more advantages in the market competition, which is conducive to expanding the market share and enhancing the enterprise's position and competitiveness in the industry. Promoting the technological progress of the industry: The application and improvement of this method provide useful references and examples for the spring steel production industry, prompting other enterprises to pay attention to and improve the problem of continuous casting billet segregation, promoting the technological progress of the entire industry in production processes and quality control, and promoting the healthy development of the spring steel industry.

[0016] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for improving the segregation of continuous casting billets of spring steel to reduce drawing and bending fractures, characterized in that: It includes the following specific method steps: S1 Continuous casting billet segregation detection: Select samples: Regularly select representative samples from the spring steel billets produced by continuous casting. For spring steel with a specification of 6.5 mm, special attention should be paid to the continuous casting billets corresponding to the batches with problems after drawing. Detect the fracture surface and metallographic structure: Conduct a fracture surface analysis on the samples, observe the macroscopic morphology of the fracture surface, and check for similar core-pulling fracture surfaces and bending fracture surfaces. S2 Optimize continuous casting process parameters: Adjust the cooling rate: In response to the problem of continuous casting billet segregation, appropriately reduce the cooling rate during continuous casting. Rapid cooling may cause the components to not have enough time to diffuse evenly, exacerbating segregation. Control the billet withdrawal speed: According to the adjustment of the cooling rate, reasonably control the billet withdrawal speed. An excessive billet withdrawal speed will cause the molten steel to solidify unevenly, aggravating segregation. After the cooling rate is reduced, the billet withdrawal speed should be correspondingly reduced to ensure that the molten steel has an appropriate solidification time in the mold. The original billet withdrawal speed is [X] m / min. After adjusting the cooling rate, the billet withdrawal speed can be reduced to [X - 0.1] - [X - 0.2] m / min. Determine the optimal billet withdrawal speed through actual production and testing to improve the segregation situation of the continuous casting billets. S3 Strengthen refining treatment: Increase the refining time: During steelmaking, extend the refining time to make the components in the molten steel more uniform. Optimize the use of refining agents: Select more suitable refining agents and optimize their usage amount and addition method. According to the composition characteristics and segregation situation of the spring steel, adjust the formula and addition amount of the refining agents. For elements prone to segregation, components of refining agents that can promote their uniform distribution can be specifically increased. S4 Quality monitoring and continuous improvement: Establish a quality inspection system: During the production process, establish a perfect quality inspection system to regularly inspect the continuous casting billets. Data analysis and process adjustment: Conduct a detailed analysis of the inspection data. If segregation problems still exist or new quality problems occur, promptly adjust the continuous casting process parameters and refining treatment methods. According to the actual production data and inspection results, continuously optimize the entire production process, continuously reduce the segregation of continuous casting billets, reduce the fracture risk of spring steel during drawing and bending, and ensure stable product quality.

2. The method for improving the segregation of continuous casting billets of spring steel to reduce drawing and bending fractures according to claim 1, characterized in that: For the detection of the fracture surface and metallographic structure, the metallographic analysis method is used. Samples are taken from the cross-section near the core-pulling fracture surface and bending fracture surface, and the metallographic structure is observed using a microscope. The key is to detect whether there are segregation bands, voids, and microcrack defects. For the problems of voids at the core of the fracture surface, segregation bands, and microcracks in the samples, the degree of segregation needs to be further analyzed.

3. The method for improving the segregation of continuous casting billets of spring steel to reduce drawing and bending fractures according to claim 1, characterized in that: For the adjustment of the cooling rate, if the original cooling rate is relatively fast, try to reduce the cooling rate by a certain proportion, such as 20% - 30%. The specific value needs to be adjusted according to the actual production situation and subsequent inspection results to ensure that the molten steel has more sufficient time for component diffusion during solidification and reduce segregation.

4. The method for improving the segregation of continuous casting billets of spring steel to reduce drawing and bending fractures according to claim 1, wherein: For the increase in refining time, if the original refining time is relatively short, appropriately increase the refining time by 10 - 15 minutes to allow various elements to fully diffuse and be evenly distributed, reducing component segregation.

5. The method for improving the segregation of continuous casting billets of spring steel to reduce drawing and bending fractures according to claim 1, characterized in that: When using the optimized refining agent, strictly control the addition time and addition sequence of the refining agent to ensure the refining effect and reduce the segregation degree of continuous casting billets.

6. The method for improving the segregation of continuous casting billets of spring steel to reduce drawing and bending fractures according to claim 1, characterized in that: When establishing the quality inspection system, conduct fracture analysis and metallographic inspection at regular intervals or after producing a certain number of continuous casting billets to monitor whether the segregation situation has been improved.