10crmoal steel plate for seawater corrosion resistance and production method thereof

Abstract

A 10CrMoAl steel plate resistant to seawater corrosion and its production method are disclosed, belonging to the field of metallurgical technology. The chemical composition and mass content of the steel plate are as follows: C: 0.08–0.11%, Si: 0.25–0.50%, Mn: 0.40–0.65%, P≤0.015%, S≤0.002%, Cr: 1.00–1.20%, Alt: 0.50–0.75%, Mo: 0.20–0.35%, with the balance being Fe and unavoidable impurities. The production method includes a smelting process, a heated rolling process, and a heat treatment process; a four-roll, two-stand rolling mill is used, with a large reduction rolling process in the roughing stage, strict control of the second-stage rolling temperature, and air cooling for normalizing. This invention ensures the comprehensive performance of steel plates without increasing costs through reasonable composition design, controlled rolling, and heat treatment processes. The steel plate thickness is 10-15mm, and the microstructure consists of ferrite and pearlite. The steel plate has a delivery state yield and tensile strength ReH≥350MPa, Rm≥490MPa, and an impact value of ≥100J at 20℃. It exhibits good impact toughness, moderate strength, and stable comprehensive performance, making it suitable for mass production.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and in particular relates to a 10CrMoAl steel plate resistant to seawater corrosion and its production method. Background Technology

[0002] The ocean is an indispensable and important part of human activities, containing abundant resources and possessing enormous economic benefits. In recent years, my country has vigorously strengthened the construction of offshore oil platforms, including oil engineering vessels and mooring terminals, pipe racks and various modules, subsea oil pipelines and their accessories, etc. The ocean is an extremely harsh and corrosive environment, and marine steel is an engineering structural material used under such conditions. Because its underwater parts are constantly corroded by seawater, sea mud, and marine microorganisms, the technical quality requirements for steel plates are extremely stringent in the selection of materials for equipment. At present, my country has made significant progress in the research and application of high-strength steel for offshore platforms, but there are still shortcomings such as low strength, incomplete specifications, and poor welding performance, which limit my country's ability to develop marine resources.

[0003] With my country's continuous exploration and development of marine resources, the demand for steel for offshore platforms is constantly expanding, and the requirements for the strength and corrosion resistance of steel plates are becoming increasingly stringent. 10CrMoAl steel plate is a specialized steel resistant to seawater corrosion, possessing excellent corrosion resistance and mechanical properties, and is widely used in marine engineering manufacturing. Therefore, the development of 10CrMoAl steel in different specifications is of great significance for the production of low-cost, high-performance seawater corrosion-resistant steel. Summary of the Invention

[0004] The purpose of this invention is to provide a 10CrMoAl steel plate with good impact toughness, moderate strength, and stable overall performance for seawater corrosion resistance, as well as its production method.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A 10CrMoAl steel plate resistant to seawater corrosion and its production method are disclosed. The chemical composition and mass percentage of the plate are as follows: C: 0.08-0.11%, Si: 0.25-0.50%, Mn: 0.40-0.65%, P≤0.015%, S≤0.002%, Cr: 1.00-1.20%, Alt: 0.50-0.75%, Mo: 0.20-0.35%, with the balance being Fe and unavoidable impurities.

[0006] Furthermore, the steel plate has a thickness of 10-15mm; the steel plate has a yield and tensile strength ReH ≥ 350MPa, Rm ≥ 490MPa, and an impact value of ≥ 100J at 20℃ in the delivery state.

[0007] The production method of 10CrMoAl steel plate for seawater corrosion resistance includes smelting process, hot rolling process and heat treatment process; (1) Smelting process: During the refining process, ensure that the amount of lime added is 200-220 kg / t, the white slag holding time is ≥35 minutes, the aluminum content of the slag is 20-25 wt%, and the S content after refining is ≤0.005 wt% before ladle lifting; During continuous casting, the superheat of the steel casting is controlled at 15℃~25℃; The liquid level control system is put into use in advance to strengthen the strong cooling at the end of solidification; The steel is stacked and slowly cooled for 20-24 hours. (2) Heating and rolling process: The continuous casting billet is heated in a continuous furnace, with a total heating time of ≥9min / cm. In the roughing stage, the longitudinal rolling is carried out in 1-3 passes with a single pass reduction of 30-35mm. After rolling to the intermediate thickness of 40-45mm, it is turned into finish rolling. The second stage rolling temperature is 880-900℃, and the pass reduction is 10-15mm. After rolling, it is air-cooled. (3) Heat treatment process: normalizing furnace, normalizing temperature 880-910℃, total heating time 2-2.5min / mm, cooling method: air cooling; tempering temperature 600-650℃, total heating time 3-4min / mm.

[0008] The design concept of this invention is as follows: The desired mechanical and corrosion resistance properties are obtained by adjusting the content of alloying elements. This invention controls key process parameters of LF and continuous casting to ensure white slag time and superheat, thereby improving the internal quality of the steel plate. A four-roll double-stand mill is used, employing a large-reduction rolling process in the roughing stage, resulting in significant internal deformation of the steel plate. This leads to a more compact and refined internal crystal structure, thereby improving the plate's strength and impact toughness. Simultaneously, the second-stage rolling temperature is strictly controlled to ensure rolling occurs in the non-recrystallization zone, increasing the deformation zone, promoting nucleation, further refining the grains, and altering the microstructure, thus further enhancing the steel plate's strength and impact toughness.

[0009] The beneficial effects of this invention are as follows: This invention, through reasonable composition design, controlled rolling and heat treatment processes, ensures the comprehensive performance of steel plates without increasing production costs. The steel plate thickness is 10-15mm, and the microstructure consists of ferrite and pearlite. The steel plate has a delivery state yield and tensile strength ReH≥350MPa, Rm≥490MPa, and an impact value of ≥100J at 20℃. It exhibits good impact toughness, moderate strength, and stable comprehensive performance, making it suitable for mass production. Attached Figure Description

[0010] Figure 1 The image shows the microstructure of the 10CrMoAl steel plate resistant to seawater corrosion obtained in Example 1. Implementation

[0011] The present invention will be further described in detail below with reference to the embodiments. Example 1

[0012] In this embodiment, the 10CrMoAl steel plate used for seawater corrosion resistance is 10mm thick, and its chemical composition and mass percentage are as follows: C: 0.08%, Si: 0.25%, Mn: 0.40%, P: 0.015%, S: 0.002%, Cr: 1.00%, Alt: 0.50%, Mo: 0.20%, with the balance being Fe and unavoidable impurities.

[0013] The production method of the 10CrMoAl steel plate for seawater corrosion resistance in this embodiment includes a smelting process, a hot rolling process, and a heat treatment process: (1) Smelting process: During refining, ensure that the amount of lime added is 200 kg / t, the white slag holding time is 35 minutes, the aluminum content of the slag is 20 wt%, and the slag is 0.005 wt% after refining. During continuous casting, the superheat of the steel is controlled at 15℃. The liquid level control system is put into operation in advance to strengthen the strong cooling at the end of solidification. The steel billets are stacked and slowly cooled for 20 hours. (2) Heating and rolling process: The continuous casting billet is heated in a continuous furnace. The total heating time is 9 min / cm. In the roughing stage, the longitudinal rolling is carried out in one pass with a single pass reduction of 30 mm. After rolling to the intermediate thickness of 40 mm, it is turned into finish rolling. The second stage rolling temperature is 880℃, and the pass reduction is 10 mm. After rolling, it is air cooled.

[0014] (3) Heat treatment process: normalizing furnace, normalizing temperature 880℃, total heating time 2min / mm, cooling method: air cooling; tempering temperature 600℃, total heating time 3min / mm.

[0015] The performance test results of the 10mm thick 10CrMoAl steel plate for seawater corrosion resistance in this embodiment are as follows: yield and tensile strength ReH 360MPa, Rm 500MPa, and impact value at 20℃ 120J. Example 2

[0016] In this embodiment, the 10CrMoAl steel plate used for seawater corrosion resistance is 15mm thick, and its chemical composition and mass percentage are as follows: C: 0.11%, Si: 0.50%, Mn: 0.65%, P: 0.014%, S: 0.001%, Cr: 1.20%, Alt: 0.75%, Mo: 0.35%, with the balance being Fe and unavoidable impurities.

[0017] The production method of 10CrMoAl steel plate for seawater corrosion resistance in this embodiment includes smelting, hot rolling and heat treatment processes: (1) Smelting process: During refining, ensure that the amount of lime added is 220 kg / t, the white slag holding time is 36 minutes, the aluminum content of the slag is 25 wt%, and the S content is 0.004 wt% after refining. During continuous casting, the superheat of the steel is controlled at 25℃. The liquid level control system is put into operation in advance to strengthen the strong cooling at the end of solidification. The steel billets are stacked and slowly cooled for 24 hours. (2) Heating and rolling process: The continuous casting billet is heated in a continuous furnace with a total heating time of 10 min / cm. In the roughing stage, the longitudinal 3-pass rolling is carried out with a single pass reduction of 35 mm. After rolling to the intermediate thickness of 45 mm, it is turned into finish rolling. The second stage rolling temperature is 900℃ with a pass reduction of 15 mm. After rolling, it is air-cooled.

[0018] (3) Heat treatment process: normalizing furnace, normalizing temperature 910℃, total heating time 2.5min / mm, cooling method: air cooling; tempering temperature 650℃, total heating time 4min / mm.

[0019] The performance test results of the 15mm thick 10CrMoAl steel plate for seawater corrosion resistance in this embodiment are as follows: yield and tensile strength ReH 480MPa, Rm 595MPa, and impact value at 20℃ 200J. Example 3

[0020] In this embodiment, the 10CrMoAl steel plate used for seawater corrosion resistance is 12mm thick, and its chemical composition and mass percentage are as follows: C: 0.10%, Si: 0.35%, Mn: 0.50%, P: 0.013%, S: 0.002%, Cr: 1.15%, Alt: 0.60%, Mo: 0.30%, with the balance being Fe and unavoidable impurities.

[0021] The production method of 10CrMoAl steel plate for seawater corrosion resistance in this embodiment includes smelting, hot rolling and heat treatment processes: (1) Smelting process: During refining, ensure the lime addition is 210 kg / t, the white slag holding time is 41 minutes, the aluminum content of the slag is 22 wt%, and the S content is 0.004 wt% after refining. During continuous casting, the superheat of the steel is controlled at 20℃. The liquid level control system is put into operation in advance to strengthen the strong cooling at the end of solidification. The steel billets are stacked for slow cooling for 22 hours. (2) Heating and rolling process: The continuous casting billet is heated in a continuous furnace with a total heating time of 13 min / cm. In the roughing stage, the longitudinal rolling is carried out in two passes with a single pass reduction of 33 mm. After rolling to the intermediate thickness of 42 mm, it is turned into finish rolling. The second stage rolling temperature is 890℃ with a pass reduction of 12 mm. After rolling, it is air-cooled.

[0022] (3) Heat treatment process: normalizing furnace, normalizing temperature 900℃, total heating time 2.2min / mm, cooling method: air cooling; tempering temperature 630℃, total heating time 3.5min / mm.

[0023] The performance test results of the 12mm thick 10CrMoAl steel plate for seawater corrosion resistance in this embodiment are as follows: yield and tensile strength ReH 450MPa, Rm 564MPa, and impact value at 20℃ 150J. Example 4

[0024] In this embodiment, the 10CrMoAl steel plate used for seawater corrosion resistance is 14mm thick, and its chemical composition and mass percentage are as follows: C: 0.09%, Si: 0.45%, Mn: 0.55%, P: 0.012%, S: 0.002%, Cr: 1.15%, Alt: 0.70%, Mo: 0.25%, with the balance being Fe and unavoidable impurities.

[0025] The production method of 10CrMoAl steel plate for seawater corrosion resistance in this embodiment includes smelting, hot rolling and heat treatment processes: (1) Smelting process: During refining, ensure that the amount of lime added is 216 kg / t, the white slag holding time is 43 minutes, the aluminum content of the slag is 21 wt%, and the S content is 0.004 wt% after refining. During continuous casting, the superheat of the steel is controlled at 22℃. The liquid level control system is put into operation in advance to strengthen the strong cooling at the end of solidification. The steel billets are stacked and slowly cooled for 21 hours. (2) Heating and rolling process: The continuous casting billet is heated in a continuous furnace with a total heating time of 11 min / cm. In the roughing stage, the longitudinal 3-pass rolling is reduced by 31 mm per pass. After rolling to the intermediate thickness of 44 mm, it is turned into finish rolling. The second stage rolling temperature is 895℃, and the reduction per pass is 14 mm. After rolling, it is air-cooled.

[0026] (3) Heat treatment process: normalizing furnace, normalizing temperature 905℃, total heating time 2.1min / mm, cooling method: air cooling; tempering temperature 610℃, total heating time 3.2min / mm.

[0027] The performance test results of the 14mm thick 10CrMoAl steel plate for seawater corrosion resistance in this embodiment are as follows: yield and tensile strength ReH 370MPa, Rm 532MPa, and impact value at 20℃ 140J.

[0028] The microstructure of the 10CrMoAl steel plate resistant to seawater corrosion obtained in Example 1 was analyzed, and the microstructure image is shown below. Figure 1 ,Depend on Figure 1 It can be seen that the structure consists of ferrite and pearlite.

[0029] The above examples are for illustrative purposes only and are not intended to limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention without departing from the spirit and scope of the present invention. Any modifications or partial substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for producing 10CrMoAl steel plate resistant to seawater corrosion, characterized in that, It includes smelting, heating and rolling, and heat treatment processes; (1) Smelting process: During the refining process, ensure that the amount of lime added is 200-220 kg / t, the white slag holding time is ≥35 minutes, the aluminum content of the slag is 20-25 wt%, and the S content after refining is ≤0.005 wt% before ladle lifting; During continuous casting, the superheat of the steel casting is controlled at 15℃~25℃; The liquid level control system is put into use in advance to strengthen the strong cooling at the end of solidification; The steel billets are stacked and cooled slowly for 20-24 hours. (2) Heating and rolling process: The continuous casting billet is heated in a continuous furnace, with a total heating time of ≥9min / cm. In the roughing stage, the longitudinal rolling is carried out in 1-3 passes with a single pass reduction of 30-35mm. After rolling to the intermediate thickness of 40-45mm, it is turned into finish rolling. The second stage rolling temperature is 880-900℃, and the pass reduction is 10-15mm. After rolling, it is air-cooled. (3) Heat treatment process: normalizing furnace, normalizing temperature 880-910℃, total heating time 2-2.5min / mm, cooling method: air cooling; tempering temperature 600-650℃, total heating time 3-4min / mm; The chemical composition and mass percentage of the steel plate are as follows: C: 0.08-0.11%, Si: 0.25-0.50%, Mn: 0.40-0.65%, P≤0.015%, S≤0.002%, Cr: 1.00-1.20%, Alt: 0.50-0.75%, Mo: 0.20-0.35%, with the balance being Fe and unavoidable impurities; The steel plate is 10-15 mm thick.

2. The method for producing 10CrMoAl steel plate resistant to seawater corrosion according to claim 1, characterized in that, The produced steel plates have a delivery state yield and tensile strength ReH≥350MPa, Rm≥490MPa, and an impact value at 20℃≥100J.

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