Production method for controlling surface scale of Ni-containing steel plate
By controlling the continuous casting and heating process, combining high-pressure water descaling and multi-stage rolling, the problem of increasing viscosity of iron oxide in high-strength medium and thick plates is solved, and a production process without additional cleaning and coating is achieved, reducing costs and Improved production efficiency.
Patent Information
- Application Number
- CN202411457947.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-18
- Publication Date
- 2025-01-07
AI Technical Summary
In the production process of high-strength medium and thick plates, with the increase of Ni element content, the viscosity of the oxide iron sheet increases after the blank is heated, making it difficult to remove, resulting in additional cleaning and applying special paints, increasing production costs and affecting the production rhythm.
By controlling the overheating, pulling speed and water volume of continuous casting, electromagnetic stirring and dynamic light pressure are used to ensure the surface quality of the casting billet, and use segmented heating and multiple high-pressure water descaling during heating and rolling, combining rough rolling and Finishing rolling process to remove iron oxide sheets and avoid surface cleaning and special coating treatment.
It realizes a production process without the need for surface cleaning and special coating treatment, reduces costs, improves the smoothness of production rhythm, and ensures that the surface of the finished steel plate is free of primary iron oxide, the thickness of secondary iron oxide is ≤0.03mm, and the surface quality of the steel plate is good.
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Figure CN119259935A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of surface quality control of thick steel plates, in particular to a production method for controlling surface iron oxide scale of a Ni-containing steel plate. Background Art
[0002] With the continuous development of medium and thick plate technology, the varieties are gradually enriched. In order to match the high strength, high-end varieties also need to obtain a certain toughness. Ni can improve the strength of steel while maintaining good plasticity and toughness. In addition, nickel has high corrosion resistance to acids and alkalis, and has rust and heat resistance at high temperatures. Therefore, adding Ni alloys has become the main choice for high-strength medium and thick plates. In actual production, as the Ni content increases, the viscosity of the iron oxide scale increases after the billet is heated, and it is difficult to remove it from the surface of the billet. The current effective treatment method is to clean the entire surface of the billet and apply special coatings on the surface of the steel plate before entering the heating furnace, which has a certain impact on production costs and production rhythm.
[0003] Therefore, developing a new production method for controlling surface oxide scale of Ni-containing steel plates is of great significance for reducing the production cost of medium and thick plates and improving the production rhythm. Summary of the invention
[0004] The problem to be solved by the present invention is that in the current production process of high-strength medium and thick plates, as the Ni content increases, the viscosity of the iron oxide scale increases after the billet is heated, and it is difficult to remove the iron oxide scale attached to the surface of the billet, and it is necessary to additionally clean the iron oxide scale on the billet surface and apply a special coating, which has a certain impact on the production cost and production rhythm. A production method for controlling the surface iron oxide scale of Ni-containing steel plates is provided.
[0005] A method for producing a Ni-containing steel plate with controlled surface oxide scale of the steel plate of the present invention comprises the following steps: (1) Continuous casting: control the superheat at 15-30°C, the casting speed at 0.80-1.15 m / min, the water volume on the wide / narrow surface of the crystallizer at 3700-4300 / 450-650 L / min, the inlet water temperature ≤36°C, the outlet water temperature ≤45°C, the inlet and outlet water temperature difference ≤9°C, electromagnetic stirring is used in zone 2 of the continuous casting machine, and dynamic soft reduction is used in zone 8; (2) Ingot cooling: The ingot is cut by an online cutting machine. After cutting, mist cooling is used to reduce the surface temperature to 700-800°C, and then slowly cooled. The slow cooling time of the ingot is not less than 48 hours. (3) Billet heating: The billet is heated in sections, and different heating temperatures are used according to the different billet thicknesses, as follows: a. When the thickness of the ingot is 150≤H≤200mm, the temperature of the first heating is 600~1000℃, the temperature of the second heating is 1150~1250℃, the temperature of the third heating is 1150~1270℃, the temperature of the soaking section is 1160~1240℃, the overall time in the furnace is not less than 160min, of which the time in the soaking section is not less than 25min; b. When the thickness of the ingot is 200<H≤250mm, the temperature of the first heating is 600~1100℃, the temperature of the second heating is 1160~1270℃, the temperature of the third heating is 1160~1270℃, the temperature of the soaking section is 1180~1250℃, and the overall time in the furnace is not less than 230min, of which the time in the soaking section is not less than 30min; c. When the thickness of the ingot is 251<H≤300mm, the temperature of the first heating is 600~1100℃, the temperature of the second heating is 1180~1250℃, the temperature of the third heating is 1180~1290℃, the temperature of the soaking section is 1170~1260℃, the overall time in the furnace is not less than 280min, of which the time in the soaking section is not less than 35min; (4) Rolling: After the ingot leaves the heating furnace and before rolling, high-pressure water descaling is performed 1 to 3 times, with an interval of 15s to 30s between each descaling, until there is no obvious large area of iron oxide on the surface of the ingot; In the rough rolling stage, the rolling temperature is ≥1100℃, the number of rolling passes is ≥4, and the machine body is descaled after the third or fourth rolling pass. After the rough rolling stage, the temperature holding time is ≥60s; In the finishing rolling stage, the starting rolling temperature is ≤960℃, the number of rolling passes in the finishing rolling stage is ≥6, the machine body is descaled in the first pass, and the machine body is descaled in the third to last pass.
[0006] The Ni-containing steel plate described in the present invention has a Ni content of 0.40-3.50% by mass.
[0007] The Ni-containing steel plate of the present invention has a finished product thickness of 6 to 120 mm, has no primary iron oxide scale on the surface, and a secondary iron oxide scale thickness of ≤0.03 mm.
[0008] The present invention provides a production method for controlling surface iron scale of a Ni-containing steel plate, the steps of which include controlling the continuous casting superheat, stretching, water volume, water temperature and other processes, and using battery stirring and dynamic light pressure to ensure the surface quality of the ingot. The ingot cooling and slow cooling process effectively improves the uniformity of the internal structure of the steel plate. Different heating processes are used for different sections, and multiple high-pressure water descaling is used to remove the primary iron scale on the surface of the ingot after it is out of the furnace; a two-stage rolling process is adopted, and the rolling temperature and rolling passes of the steel plate are controlled during the rough rolling process, and a certain waiting time is ensured between the two stages, so that the secondary iron scale on the surface of the steel plate is fully formed during the rolling process, and then the body descaling is used in the finishing rolling stage to remove it, and the surface temperature of the steel plate is controlled during the subsequent rolling process, so as to effectively improve the surface quality of the Ni-containing steel plate. The Ni-containing steel plate produced by the method of the present invention does not need to be cleaned on the entire surface and treated with special coatings, which does not affect the production rhythm, has a smooth process and low cost. After the billet is descaled, the surface oxide scale is cleaned, the surface of the finished steel plate has no primary oxide scale, the thickness of the secondary oxide scale is ≤0.03mm, and the surface quality of the steel plate is good. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 This is a photo of the steel plate prepared in Example 2 of the present invention after the ingot is descaled by high-pressure water after leaving the heating furnace; Figure 2 This is a photo of the finished steel plate prepared in Example 2 of the present invention. DETAILED DESCRIPTION
[0010] In order to better explain the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with specific embodiments. The following embodiments are merely exemplary of the technical solution of the present invention and do not limit the present invention in any form. The serial numbers of the following embodiments are only for description and do not represent the advantages and disadvantages of the embodiments.
[0011] Table 1 below is a list of steel plate casting information and parameter values of continuous casting process in various embodiments of the present invention; Table 2 below is a list of parameter values for the slow cooling and heating processes of the steel plates of various embodiments of the present invention; Table 3 below is a list of descaling process parameter values for the steel plate rolling process according to various embodiments of the present invention; Table 4 below is a list of surface quality inspection results of the steel plates of various embodiments of the present invention.
[0012] A method for producing a Ni-containing steel plate with controlled surface oxide scale according to each embodiment of the present invention comprises the following steps: (1) Continuous casting: control the superheat at 15-30°C, the casting speed at 0.80-1.15 m / min, the water volume on the wide / narrow surface of the crystallizer at 3700-4300 / 450-650 L / min, the inlet water temperature ≤36°C, the outlet water temperature ≤45°C, the inlet and outlet water temperature difference ≤9°C, electromagnetic stirring is used in zone 2 of the continuous casting machine, and dynamic soft reduction is used in zone 8; (2) Ingot cooling: The ingot is cut by an online cutting machine. After cutting, mist cooling is used to reduce the surface temperature to 700-800°C, and then slowly cooled. The slow cooling time of the ingot is not less than 48 hours. (3) Billet heating: The billet is heated in sections, and different heating temperatures are used according to the different billet thicknesses, as follows: a. When the thickness of the ingot is 150≤H≤200mm, the temperature of the first heating is 600~1000℃, the temperature of the second heating is 1150~1250℃, the temperature of the third heating is 1150~1270℃, the temperature of the soaking section is 1160~1240℃, the overall time in the furnace is not less than 160min, of which the time in the soaking section is not less than 25min; b. When the thickness of the ingot is 200<H≤250mm, the temperature of the first heating is 600~1100℃, the temperature of the second heating is 1160~1270℃, the temperature of the third heating is 1160~1270℃, the temperature of the soaking section is 1180~1250℃, and the overall time in the furnace is not less than 230min, of which the time in the soaking section is not less than 30min; c. When the thickness of the ingot is 251<H≤300mm, the temperature of the first heating is 600~1100℃, the temperature of the second heating is 1180~1250℃, the temperature of the third heating is 1180~1290℃, the temperature of the soaking section is 1170~1260℃, the overall time in the furnace is not less than 280min, of which the time in the soaking section is not less than 35min; (4) Rolling: After the ingot leaves the heating furnace and before rolling, high-pressure water descaling is performed 1 to 3 times, with an interval of 15s to 30s between each descaling, until there is no obvious large area of iron oxide on the surface of the ingot; In the rough rolling stage, the rolling temperature is ≥1100℃, the number of rolling passes is ≥4, and the machine body is descaled after the third or fourth rolling pass. After the rough rolling stage, the temperature holding time is ≥60s; In the finishing rolling stage, the starting rolling temperature is ≤960℃, the number of rolling passes in the finishing rolling stage is ≥6, the machine body is descaled in the first pass, and the machine body is descaled in the third to last pass.
[0013] Table 1 List of steel plate casting information and parameter values of continuous casting process in various embodiments of the present invention
[0014] Table 2 List of parameter values for the slow cooling and heating process of the steel plate in various embodiments of the present invention
[0015] Table 3 List of descaling process parameter values for the steel plate rolling process in various embodiments of the present invention
[0016] Table 4 List of surface quality inspection results of steel plates in various embodiments of the present invention
[0017] It can be seen from Tables 1 to 4 above that the Ni-containing ingots implemented in accordance with Tables 1 to 3 do not need to be cleaned on the entire surface and treated with special coatings, which does not affect the production rhythm, the process is smooth, and the production cost is low. After the ingots are descaled, the surface oxide scale is cleaned, and there is no primary oxide scale on the surface of the finished steel plate, the thickness of the secondary oxide scale is ≤0.03mm, and the surface quality of the steel plate is good.
[0018] Attached Figure 1 Attached is a photo of the steel plate prepared in Example 2 of the present invention after the ingot is descaled by high-pressure water after leaving the heating furnace; Figure 2 This is a photo of the finished steel plate prepared in Example 2 of the present invention. Figure 1 It can be seen that after the ingot is descaled by high-pressure water after leaving the heating furnace, the iron oxide scale is relatively clean; Figure 2 It can be seen that there is no primary or secondary iron oxide scale on the surface of the steel plate, and the quality is good.
[0019] The above embodiments are only specific examples for explaining the present invention and do not limit the present invention in any form. Any non-substantial changes made by anyone based on the above contents and forms without departing from the protection scope of the claims of the present invention shall be deemed to fall within the protection scope of the claims of the present invention. The present invention is not limited to the above specific implementation examples.
Claims
1. A method for producing a Ni-containing steel plate with controlled surface oxide scale, characterized in that The steps include: (1) Continuous casting: control the superheat at 15-30°C, the casting speed at 0.80-1.15 m / min, the water volume on the wide / narrow surface of the crystallizer at 3700-4300 / 450-650 L / min, the inlet water temperature ≤36°C, the outlet water temperature ≤45°C, the inlet and outlet water temperature difference ≤9°C, electromagnetic stirring is used in zone 2 of the continuous casting machine, and dynamic soft reduction is used in zone 8; (2) Ingot cooling: The ingot is cut by an online cutting machine. After cutting, mist cooling is used to reduce the surface temperature to 700-800°C, and then slowly cooled. The slow cooling time of the ingot is not less than 48 hours. (3) Billet heating: The billet is heated in sections, and different heating temperatures are used according to the different billet thicknesses, as follows: a. When the thickness of the ingot is 150≤H≤200mm, the temperature of the first heating is 600~1000℃, the temperature of the second heating is 1150~1250℃, the temperature of the third heating is 1150~1270℃, the temperature of the soaking section is 1160~1240℃, the overall time in the furnace is not less than 160min, of which the time in the soaking section is not less than 25min; b. When the thickness of the ingot is 200<H≤250mm, the temperature of the first heating is 600~1100℃, the temperature of the second heating is 1160~1270℃, the temperature of the third heating is 1160~1270℃, the temperature of the soaking section is 1180~1250℃, and the overall time in the furnace is not less than 230min, of which the time in the soaking section is not less than 30min; c. When the thickness of the ingot is 251<H≤300mm, the temperature of the first heating is 600~1100℃, the temperature of the second heating is 1180~1250℃, the temperature of the third heating is 1180~1290℃, the temperature of the soaking section is 1170~1260℃, the overall time in the furnace is not less than 280min, of which the time in the soaking section is not less than 35min; (4) Rolling: After the ingot leaves the heating furnace and before rolling, high-pressure water descaling is performed 1 to 3 times, with an interval of 15s to 30s between each descaling, until there is no obvious large area of iron oxide on the surface of the ingot; In the rough rolling stage, the rolling temperature is ≥1100℃, the number of rolling passes is ≥4, and the machine body is descaled after the third or fourth rolling pass. After the rough rolling stage, the temperature holding time is ≥60s; In the finishing rolling stage, the starting rolling temperature is ≤960℃, the number of rolling passes in the finishing rolling stage is ≥6, the machine body is descaled in the first pass, and the machine body is descaled in the third to last pass.
2. The method for producing a Ni-containing steel plate with controlled surface oxide scale according to claim 1, characterized in that: The mass percentage of Ni in the Ni-containing steel plate is 0.40-3.50%.
3. The method for producing a Ni-containing steel plate with controlled surface oxide scale according to claim 1, characterized in that: The Ni-containing steel plate has a finished product thickness of 6-120 mm, has no primary iron oxide scale on the surface, and a secondary iron oxide scale thickness of ≤0.03 mm.