Production method for improving production plate shape of pipeline steel

Abstract

The invention discloses a production method for improving the production plate shape of pipeline steel. The pipeline steel comprises the following chemical components in percentage by mass: 0.02-0.09% of C, 0.6-1.80% of Mn, less than or equal to 0.30% of Si, less than or equal to 0.020% of P, less than or equal to 0.005% of S, less than or equal to 0.00005% of N and the balance of iron and inevitable impurities. The method has the advantages that the cooling uniformity of the pipeline steel in the rolling direction is improved by controlling the austenitizing temperature, optimizing the rolling schedule and adopting the process of sectional water ratio and sectional cooling, so that the production plate type of a steel plate is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a production method for improving the plate shape of pipeline steel production. Background Art

[0002] With the continuous development of economy, the demand for oil has become more urgent. Therefore, the steel for oil pipeline has been vigorously developed. Pipeline steel adopts TMCP rolling technology, so the plate shape control is difficult, and the plate shape has a great influence on the performance of the product. The fluctuation of plate shape often brings the fluctuation of performance. Therefore, the reasonable control of pipeline steel production plate shape is the key and one of the difficulties in pipeline steel manufacturing. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of difficulty in controlling the plate shape and low performance stability in the existing pipeline steel production, and to provide a production method for improving the plate shape of pipeline steel production, which can improve the surface quality and the plate shape stability of the production process, and enhance the uniformity of product performance and the competitiveness of the product.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: A production method for improving the plate shape of pipeline steel production, comprising the following chemical composition and mass percentage of the pipeline steel: C: 0.02-0.09, Mn: 0.6-1.80, Si: ≤0.30, P: ≤0.020, S: ≤0.005, N: ≤0.00005, and the balance is iron and unavoidable impurities.

[0005] Furthermore, the chemical composition and mass percentage of the pipeline steel are as follows: C: 0.06, Mn: 1.55, Si: 0.23, P: 0.011, S: 0.002, N: 0.00041, and the remainder is iron and unavoidable impurities.

[0006] Furthermore, the chemical composition and mass percentage of the pipeline steel are as follows: C: 0.03, Mn: 0.87, Si: 0.16, P: 0.016, S: 0.002, N: 0.00038, and the balance is iron and unavoidable impurities.

[0007] Furthermore, the pipeline steel is produced according to the following steps, specifically including: (S1) Smelting: using converter or electric furnace for smelting, vacuum refining to effectively remove impurities and harmful gases, and then continuous casting and billet cooling; (S2) Rolling: austenitizing is performed at a temperature of 1120-1150°C, the heating time is 9-15 min / cm, the soaking time is 2-3 min / cm, primary dephosphorization is performed after the furnace, and two-stage rolling is performed after dephosphorization. The rolling force of the two passes after finishing rolling is 4000-6000 KN; (S3) Cooling: water inlet temperature 730-760°C, cooling rate 10-20°C / s, water ratio of the first 4 groups is set to 1.2-1.4, and water ratio of the last 4 groups is set to 1.3-1.5.

[0008] Furthermore, in the step (S2), during the rolling process, the heating temperature is 1131°C, the heating time is 13 min / cm, and the soaking time is 2.3 min / cm.

[0009] Furthermore, in the step (S2), during the rolling process, the heating temperature is 1143°C, the heating time is 13 min / cm, and the soaking time is 2.9 min / cm.

[0010] Furthermore, in the step (S3), the water inlet temperature during cooling is 746°C, the cooling rate is 16°C / s, the water ratio of the first 4 groups is set to 1.3, and the water ratio of the last 4 groups is set to 1.45.

[0011] Furthermore, in the step (S3), the water inlet temperature during cooling is 756°C, the cooling rate is set to 16°C / s, the water ratio of the first 4 groups is set to 1.26, and the water ratio of the last 4 groups is set to 1.47.

[0012] Furthermore, in the step (S2), during the rolling process, the thickness of the warm billet is set to be ≥3.0 times the thickness of the steel plate to ensure the reduction amount of the finishing pass.

[0013] Furthermore, in the step (S2), during the rolling process, the final rolling temperature is controlled at 750-850°C.

[0014] Compared with the prior art, the advantages of the technical solution of the present invention are: (1) The present invention adopts a low-carbon design and reduces the amount of Si content, avoiding the generation of FeSiO4 scale, making the surface of the steel plate smoother and more uniform, reducing defects, and making the cooling process more uniform. Therefore, the cooling of the steel plate surface is more stable, effectively improving the production shape of the steel plate; (2) The present invention performs austenitization at a temperature of 1120-1150°C, thereby reducing the amount of iron oxide scale generated during the secondary heating of the ingot, making the iron oxide scale on the surface of the steel plate thinner, and improving the heat exchange of the steel plate during the cooling process. Therefore, the application of low-temperature technology improves the production shape of the steel plate; (3) The present invention reduces stress changes and plate shape changes during the rolling process by controlling the rolling force of 4000-6000 kN in two passes after finishing rolling, optimizes the rolled plate shape, improves the instability during the cooling process, and improves the stability of the produced plate shape; (4) The present invention controls the final rolling temperature below 750-850°C, which reduces the production of iron oxide scale during the rolling process, ensures the improvement of the surface quality of the steel plate, and is conducive to the stability of the cooling process; (5) The inlet water temperature during the cooling process of the present invention is crucial to the change in surface quality, which reduces the temperature fluctuation gradient and the deformation of the steel plate, and has the effect of effectively improving the steel plate production shape. The application of segmented water ratio ensures the cooling rate during the steel plate manufacturing process, and the steel plate outlet shape is more stable, further improving the stability of the production shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a metallographic structure diagram of the steel plate surface in Example 1 of the present invention. DETAILED DESCRIPTION Example 1

[0016] To make the present invention more clearly understood, a production method for improving the plate shape of pipeline steel production according to the present invention is further described below in conjunction with the accompanying drawings. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] In this embodiment, the chemical composition and mass percentage of the pipeline steel are as follows: C: 0.06, Mn: 1.55, Si: 0.23, P: 0.011, S: 0.002, N: 0.00041, and the remainder is iron and unavoidable impurities.

[0018] Meanwhile, corresponding to the above-mentioned embodiment, a production method for improving the profile of pipeline steel plate comprises the following steps: (1) Smelting: Use converter or electric furnace for smelting, effectively remove impurities and harmful gases through vacuum refining, and pile cool the billet after continuous casting; (2) Rolling: Austenitizing is performed at 1131°C, the heating time is 13 min / cm, the soaking time is 2.3 min / cm, and the initial dephosphorization is performed after the furnace. After dephosphorization, two-stage rolling is performed. The rolling force of the two passes after finishing rolling is 4000-6000 KN. (3) Cooling: water inlet temperature 746°C, cooling rate 16°C / s, water ratio of the first 4 groups set to 1.3, and water ratio of the last 4 groups set to 1.45.

[0019] In this embodiment, the thickness of the warm billet is set to be ≥3.0 times the thickness of the steel plate to ensure the reduction amount of the finishing pass.

[0020] In this embodiment, in the rolling process, the final rolling temperature is controlled below 789°C. Example 2

[0021] In this embodiment, the chemical composition and mass percentage of the pipeline steel are as follows: C: 0.03, Mn: 0.87, Si: 0.16, P: 0.016, S: 0.002, N: 0.00038, and the remainder is iron and unavoidable impurities.

[0022] Meanwhile, corresponding to the above-mentioned embodiment, a production method for improving the profile of pipeline steel plate comprises the following steps: (1) Smelting: Use converter or electric furnace for smelting, effectively remove impurities and harmful gases through vacuum refining, and pile cool the billet after continuous casting; (2) Rolling: Austenitizing was performed at 1143°C, the heating time was 13 min / cm, the soaking time was 2.9 min / cm, and the steel was initially dephosphorized after being taken out of the furnace. After dephosphorization, two-stage rolling was performed. The rolling force of the two passes after finishing rolling was 4500 KN. (3) Cooling: water inlet temperature 756°C, cooling rate 16°C / s, water ratio of the first 4 groups set to 1.26, and water ratio of the last 4 groups set to 1.47.

[0023] In this embodiment, in the rolling process, the thickness of the warm billet is set to be ≥ 3.0 times the thickness of the steel plate to ensure the reduction amount of the finishing pass.

[0024] In this embodiment, in the rolling process, the final rolling temperature is controlled below 823°C.

[0025] The present invention starts with component design, optimizes the rolling procedure through austenitizing temperature control, adopts segmented water ratio and segmented cooling processes to improve the cooling uniformity of pipeline steel in the rolling direction, improves the surface quality, and improves the plate shape stability of the production process through water ratio setting during the rolling process, thereby improving the uniformity of product performance, improving product competitiveness, and improving the image of the enterprise.

[0026] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A production method for improving the plate shape of pipeline steel production, characterized in that: The chemical composition and mass percentage of the pipeline steel are as follows: C: 0.02-0.09, Mn: 0.6-1.80, Si: ≤0.30, P: ≤0.020, S: ≤0.005, N: ≤0.00005, and the balance is iron and unavoidable impurities.

2. The method for improving the production profile of pipeline steel according to claim 1, characterized in that: The chemical composition and mass percentage of the pipeline steel are as follows: C: 0.06, Mn: 1.55, Si: 0.23, P: 0.011, S: 0.002, N: 0.00041, and the remainder is iron and unavoidable impurities.

3. The method for improving the production profile of pipeline steel according to claim 1, characterized in that: The chemical composition and mass percentage of the pipeline steel are as follows: C: 0.03, Mn: 0.87, Si: 0.16, P: 0.016, S: 0.002, N: 0.00038, and the balance is iron and unavoidable impurities.

4. The method for improving the production profile of pipeline steel according to claim 1, characterized in that: (S1) Smelting: using converter or electric furnace for smelting, vacuum refining to effectively remove impurities and harmful gases, and then continuous casting and billet cooling; (S2) Rolling: austenitizing is performed at a temperature of 1120-1150°C, the heating time is 9-15 min / cm, the soaking time is 2-3 min / cm, primary dephosphorization is performed after the furnace, and two-stage rolling is performed after dephosphorization. The rolling force of the two passes after finishing rolling is 4000-6000 KN; (S3) Cooling: water inlet temperature 730-760°C, cooling rate 10-20°C / s, water ratio of the first 4 groups is set to 1.2-1.4, and water ratio of the last 4 groups is set to 1.3-1.

5.

5. The method for improving the production profile of pipeline steel according to claim 4, characterized in that: In the step (S2), during the rolling process, the heating temperature is 1131°C, the heating time is 13 min / cm, and the soaking time is 2.3 min / cm.

6. The method for improving the production profile of pipeline steel according to claim 4, characterized in that: In the step (S2), during the rolling process, the heating temperature is 1143°C, the heating time is 13 min / cm, and the soaking time is 2.9 min / cm.

7. The method for improving the production profile of pipeline steel according to any one of claims 4 to 6, characterized in that: In the step (S3), the water inlet temperature during cooling is 746°C, the cooling rate is 16°C / s, the water ratio of the first 4 groups is set to 1.3, and the water ratio of the last 4 groups is set to 1.

45.

8. The method for improving the production shape of pipeline steel according to any one of claims 4 to 6, characterized in that: In the step (S3), the water inlet temperature during cooling is 756°C, the cooling rate is set to 16°C / s, the water ratio of the first 4 groups is set to 1.26, and the water ratio of the last 4 groups is set to 1.

47.

9. The method for improving the production profile of pipeline steel according to any one of claims 4 to 6, characterized in that: In the step (S2), during the rolling process, the thickness of the warm billet is set to be ≥3.0 times the thickness of the steel plate to ensure the reduction amount of the finishing rolling pass.

10. The method for improving the production shape of pipeline steel according to any one of claims 4 to 6, characterized in that: In the step (S2), during the rolling process, the final rolling temperature is controlled at 750-850°C.

Images