Large-wall-thickness energy steel plate and manufacturing method thereof

Abstract

The invention discloses a large-wall-thickness steel plate for energy. The steel plate comprises the following chemical components in percentage by mass: 0.09 to 0.13 percent of C, 0.10 to 0.30 percent of Si, 1.60 to 1.70 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.005 percent of S, 0.010 to 0.020 percent of Nb, 0.010 to 0.030 percent of V, 0.015 to 0.025 percent of Ti, 0.0010 to 0.0040 percent of Ca, 0.020 to 0.050 percent of Al and the balance of Fe and inevitable impurities. The steel plate has the advantages that casting and rolling processes are combined on the basis of component design, the flaw detection capacity and stable mechanical properties of products are improved, the requirements of large-thickness energy steel are met, and the core competitiveness of plate products is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a thick steel plate for energy use and a manufacturing method thereof. Background Art

[0002] With the active promotion of green buildings, the development of green buildings has become a good way to cope with the dual challenges of environment and economy. Green buildings and building industrialization will be the main direction of a new round of scientific and technological innovation and industrial transformation and upgrading. Therefore, the demand for large-walled energy-grade steel will also increase accordingly.

[0003] At present, the direct production of large-thickness container steel plates over 100mm using continuous casting billets has low production efficiency and high energy consumption. The welding performance of thick energy steel cannot be guaranteed, and the quality of the core of the billet is not high, resulting in a significant reduction in the product's flaw detection pass rate. The performance uniformity and stability of the steel plates cannot meet the requirements of large-scale stable production. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems of low production efficiency, high energy consumption, poor performance and low qualified rate of existing large-thickness energy steel. It provides a large-walled energy steel plate, which is based on composition design and combined with casting and rolling processes to improve the product's flaw detection capability and stable mechanical properties, meet the needs of large-thickness energy steel, and enhance the core competitiveness of plate products.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A thick-walled energy steel plate comprises the following chemical compositions and weight percentages: C: 0.09-0.13%, Si: 0.10-0.30%, Mn: 1.60-1.70%, P≤0.020%, S≤0.005%, Nb: 0.010-0.020%, V: 0.010-0.030%, Ti: 0.015%-0.025%, Ca: 0.0010-0.0040%, Al: 0.020-0.050%, and the balance being Fe and unavoidable impurities.

[0006] Furthermore, the chemical composition and mass percentage of the heavy-walled energy steel plate include: C: 0.09-0.11%, Si: 0.10-0.20%, Mn: 1.60-1.69%, P≤0.018%, S≤0.003%, Nb: 0.010-0.019%, V: 0.010-0.020%, Ti: 0.015%-0.023%, Ca: 0.0010-0.0030%, Al: 0.020-0.045%, and the balance is Fe and unavoidable impurities.

[0007] Furthermore, the chemical composition and mass percentage of the heavy-walled energy steel plate include: C: 0.11-0.13%, Si: 0.20-0.30%, Mn: 1.61-1.70%, P≤0.015%, S≤0.003%, Nb: 0.011-0.020%, V: 0.020-0.030%, Ti: 0.016%-0.025%, Ca: 0.0015-0.0040%, Al: 0.021-0.050%, and the balance is Fe and unavoidable impurities.

[0008] Furthermore, the chemical composition and mass percentage of the heavy-walled energy steel plate include: C: 0.10-0.12%, Si: 0.15-0.25%, Mn: 1.60-1.70%, P≤0.013%, S≤0.002%, Nb: 0.010-0.020%, V: 0.015-0.025%, Ti: 0.015%-0.025%, Ca: 0.0015-0.0035%, Al: 0.020-0.050%, N≤0.0060, H≤0.00020; the balance is Fe and unavoidable impurities.

[0009] In order to further achieve the purpose of the present invention, a method for manufacturing a thick steel plate for energy use is also provided, comprising the following steps: (1) Smelting: Desulfurized molten iron is smelted in a converter or electric furnace, and then sent to refining for treatment. The high vacuum degassing time is not less than 20 minutes, and the molten steel is purified by calcium treatment; (2) Casting: Use 320mm~460mm cross section for casting, apply alternating electromagnetic stirring technology, electromagnetic stirring current 380A, frequency 6.0; casting speed 0.50~0.70m / min, superheat 10~20℃, and pile cooling of billet for 48h after casting; (3) Rolling: adopt two-stage rolling process, the second rolling temperature is 800-900℃, the rolling speed is 2.0m / s, the initial rolling reduction rate is not less than 20%; the cooling roller speed is 0.2-0.3±5m / s, the acceleration is 0.001-0.003m / s², the red-return temperature is 550-750℃, and the steel plate is directly put into the pile cooling pit for pile cooling, and the pile cooling time is 20-30h; (4) Heat treatment: After the steel plate is shot blasted after stack cooling, it is subjected to normalizing heat treatment. The normalizing temperature is 900-920℃ and the holding time is 3Hmin / mm, where H is the thickness of the steel plate in mm. After normalizing, the steel plate is water-cooled to 550-600℃ and then air-cooled. (5) Warehousing: Sampling, marking, flaw detection and warehousing of heat-treated steel plates.

[0010] Furthermore, the steel grade of the steel plate is Q235~Q420Mpa, and the steel plate performance meets the requirements of transverse tensile performance, -20℃ longitudinal impact performance, 180℃ 3a cold bending and Z-direction tensile performance.

[0011] Furthermore, the thickness of the steel plate is 100-300 mm, and the width is 1500-4500 mm.

[0012] Compared with the prior art, the advantages of the technical solution of the present invention are: (1) The present invention meets the demand for easy welding of products through the design of low carbon, high manganese and micro niobium, and the appropriate addition of trace elements, thereby improving the welding performance of thick wall energy; (2) The present invention improves the core quality of the ingot and increases the flaw detection qualification rate of the product through high vacuum, low hydrogen and low nitrogen design and process control methods, combined with low over-degree control and casting speed control during the smelting process; (3) The present invention adopts a second-pass temperature of no more than 900°C, which increases the final reduction rate, high red-return and stack cooling time. By means of high-temperature and large-reduction methods, the core quality of energy steel is improved, and the level of flaw detection qualification rate is further improved; (4) The present invention adopts the normalizing process, which effectively refines the grain size of the structure, improves the stability of the mechanical properties and impact properties of the product, and at the same time greatly improves the performance uniformity of the steel plate; (5) The process route of the present invention has a large industrial production process window and can achieve large-scale stable production, thereby improving the production efficiency of thick-walled energy-using steel plates and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the metallographic structure diagram of the steel plate in Example 1 of the present invention. DETAILED DESCRIPTION Example 1

[0014] To make the present invention more clear, a thick steel plate for energy use and a manufacturing method thereof of the present invention are further described below. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0015] In this embodiment, a thick-walled energy steel plate has a thickness of 120 mm, and its chemical composition and mass percentage include: C: 0.10%, Si: 0.13%, Mn: 1.63%, P: 0.013%, S: 0.002%, Nb: 0.016%, V: 0.013%, Ti: 0.019%, Ca: 0.0021%, Al: 0.035%, and the balance is Fe and unavoidable impurities.

[0016] The method for manufacturing the above-mentioned thick steel plate for energy use comprises the following steps, which are characterized in that: (1) Smelting: Desulfurized molten iron is smelted in a converter or electric furnace, and then sent to refining for treatment. The high vacuum degassing time is 23 minutes, and the molten steel is purified by calcium treatment; (2) Casting: 320mm cross section was used for casting, and alternating electromagnetic stirring technology was applied. The electromagnetic stirring current was 380A and the frequency was 6.0. The casting speed was 0.63m / min and the superheat was 12℃. After casting, the blank was pile-cooled for 48h. (3) Rolling: A two-stage rolling process was adopted, with a second rolling temperature of 893°C, a rolling speed of 2.0 m / s, a final reduction rate of 26% in the initial rolling process, a cooling roll speed of 0.2 m / s, an acceleration of 0.002 m / s², a red-return temperature of 630°C, and the steel plate was directly placed in the cooling pit for cooling, with a cooling time of 26 h. (4) Heat treatment: After the pile cooling, the steel plate is shot blasted and then subjected to normalizing heat treatment. The normalizing temperature is 909 ° C and the holding time is 360 min. After normalizing, the steel plate is water-cooled to 580 ° C and then air-cooled. (5) Warehousing: Sampling, marking, flaw detection and warehousing of heat-treated steel plates.

[0017] The metallographic structure of the steel plate prepared by the method of this embodiment is as follows: Figure 1 shown. Example 2

[0018] In this embodiment, a thick-walled energy steel plate has a thickness of 260 mm, and its chemical composition and mass percentage include: C: 0.12%, Si: 0.27%, Mn: 1.68%, P: 0.014%, S: 0.001%, Nb: 0.017%, V: 0.027%, Ti: 0.022%, Ca: 0.0030%, Al: 0.041%, and the remainder is Fe and unavoidable impurities.

[0019] The method for manufacturing the above-mentioned thick steel plate for energy use comprises the following steps, which are characterized in that: (1) Smelting: Desulfurized molten iron is smelted in a converter or electric furnace, and then sent to refining for treatment. The high vacuum degassing time is 24 minutes, and the molten steel is purified by calcium treatment; (2) Casting: 460mm cross section was used for casting, and alternating electromagnetic stirring technology was applied. The electromagnetic stirring current was 380A and the frequency was 6.0. The casting speed was 0.50m / min and the superheat was 16℃. After casting, the blank was piled and cooled for 48h. (3) Rolling: A two-stage rolling process was adopted, with a second rolling temperature of 820°C, a rolling speed of 2.0 m / s, a final reduction rate of 29% in the initial rolling process, a cooling roll speed of 0.25 m / s, an acceleration of 0.001 m / s², a red-return temperature of 570°C, and the steel plate was directly placed in the cooling pit for cooling, with a cooling time of 29 h. (4) Heat treatment: After the pile cooling, the steel plate is shot blasted and then subjected to normalizing heat treatment. The normalizing temperature is 917 ° C and the holding time is 780 min / mm. After normalizing, the steel plate is water-cooled to 560 ° C and then air-cooled. (5) Warehousing: Sampling, marking, flaw detection and warehousing of heat-treated steel plates. Example 3

[0020] In this embodiment, a thick-walled energy steel plate has a thickness of 220 mm, and its chemical composition and mass percentage include: C: 0.11%, Si: 0.16%, Mn: 1.63%, P: 0.011%, S: 0.002%, Nb: 0.019%, V: 0.017%, Ti: 0.019%, Ca: 0.0031%, Al: 0.042%, N: 0.0030, H: 0.00010; the remainder is Fe and unavoidable impurities.

[0021] The method for manufacturing the above-mentioned thick steel plate for energy use comprises the following steps, which are characterized in that: (1) Smelting: Desulfurized molten iron is smelted in a converter or electric furnace, and then sent to refining for treatment. The high vacuum degassing time is 26 minutes, and the molten steel is purified by calcium treatment; (2) Casting: 460mm cross section was used for casting, and alternating electromagnetic stirring technology was applied. The electromagnetic stirring current was 380A and the frequency was 6.0. The casting speed was 0.50m / min and the superheat was 15℃. After casting, the blank was piled and cooled for 48h. (3) Rolling: A two-stage rolling process was adopted, with a second rolling temperature of 830°C, a rolling speed of 2.0 m / s, a final reduction rate of 27% in the initial rolling process, a cooling roll speed of 0.2 m / s, an acceleration of 0.001 m / s², a red-return temperature of 580°C, and the steel plate was directly placed in the cooling pit for cooling, with a cooling time of 29 h. (4) Heat treatment: After the pile cooling, the steel plate is shot blasted and then subjected to normalizing heat treatment. The normalizing temperature is 913 ° C and the holding time is 660 min / mm. After normalizing, the steel plate is water-cooled to 590 ° C and then air-cooled. (5) Warehousing: Sampling, marking, flaw detection and warehousing of heat-treated steel plates.

[0022] The present invention appropriately adds trace elements to improve the welding performance of thick-walled energy steel plates. At the same time, through high vacuum, low hydrogen and low nitrogen design and high temperature and large pressure reduction means, the core quality of energy steel is improved and the flaw detection pass rate is increased; the grain size of the structure is effectively refined, and the mechanical properties and impact performance stability of the product are improved. The method of the present invention can achieve large-scale stable production, thereby improving the production efficiency of thick-walled energy steel plates and reducing energy consumption.

[0023] In addition to the above embodiments, the present invention may also have other implementations. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A thick steel plate for energy use, characterized by: The chemical composition and mass percentage of the steel plate include: C: 0.09-0.13%, Si: 0.10-0.30%, Mn: 1.60-1.70%, P≤0.020%, S≤0.005%, Nb: 0.010-0.020%, V: 0.010-0.030%, Ti: 0.015%-0.025%, Ca: 0.0010-0.0040%, Al: 0.020-0.050%, and the balance is Fe and unavoidable impurities.

2. The thick steel plate for energy use according to claim 1, characterized in that: The chemical composition and mass percentage of the heavy-walled energy steel plate include: C: 0.09-0.11%, Si: 0.10-0.20%, Mn: 1.60-1.69%, P≤0.018%, S≤0.003%, Nb: 0.010-0.019%, V: 0.010-0.020%, Ti: 0.015%-0.023%, Ca: 0.0010-0.0030%, Al: 0.020-0.045%, and the balance is Fe and unavoidable impurities.

3. The thick steel plate for energy use according to claim 1, characterized in that: The chemical composition and mass percentage of the heavy-walled energy steel plate include: C: 0.11-0.13%, Si: 0.20-0.30%, Mn: 1.61-1.70%, P≤0.015%, S≤0.003%, Nb: 0.011-0.020%, V: 0.020-0.030%, Ti: 0.016%-0.025%, Ca: 0.0015-0.0040%, Al: 0.021-0.050%, and the remainder is Fe and unavoidable impurities.

4. The heavy-walled steel plate for energy use according to claim 1, characterized in that: The chemical composition and mass percentage of the heavy-walled energy steel plate include: C: 0.10-0.12%, Si: 0.15-0.25%, Mn: 1.60-1.70%, P≤0.013%, S≤0.002%, Nb: 0.010-0.020%, V: 0.015-0.025%, Ti: 0.015%-0.025%, Ca: 0.0015-0.0035%, Al: 0.020-0.050%, N≤0.0060, H≤0.00020; the balance is Fe and unavoidable impurities.

5. A method for manufacturing a thick steel plate for energy use according to claim 1, comprising the following steps, characterized in that: (1) Smelting: Desulfurized molten iron is smelted in a converter or electric furnace, and then sent to refining for treatment. The high vacuum degassing time is not less than 20 minutes, and the molten steel is purified by calcium treatment; (2) Casting: Use 320mm~460mm cross section for casting, apply alternating electromagnetic stirring technology, electromagnetic stirring current 380A, frequency 6.0; casting speed 0.50~0.70m / min, superheat 10~20℃, and pile cooling of billet for 48h after casting; (3) Rolling: adopt two-stage rolling process, the second rolling temperature is 800-900℃, the rolling speed is 2.0m / s, the initial rolling reduction rate is not less than 20%; the cooling roller speed is 0.2-0.3±5m / s, the acceleration is 0.001-0.003m / s², the red-return temperature is 550-750℃, and the steel plate is directly put into the pile cooling pit for pile cooling, and the pile cooling time is 20-30h; (4) Heat treatment: After the steel plate is shot blasted after stack cooling, it is subjected to normalizing heat treatment. The normalizing temperature is 900-920℃ and the holding time is 3Hmin / mm, where H is the thickness of the steel plate in mm. After normalizing, the steel plate is water-cooled to 550-600℃ and then air-cooled. (5) Warehousing: Sampling, marking, flaw detection and warehousing of heat-treated steel plates.

6. The method for manufacturing a thick steel plate for energy use according to claim 5, characterized in that: The steel grade of the steel plate is Q235~Q420Mpa.

7. The method for manufacturing a thick steel plate for energy use according to claim 6, wherein: The thickness specification of the steel plate is 100-300 mm, and the width specification is 1500-4500 mm.

8. The method for manufacturing a thick steel plate for energy use according to claim 7, wherein: The thickness of the steel plate is 120 mm, and its chemical composition and mass percentage include: C: 0.10%, Si: 0.13%, Mn: 1.63%, P: 0.013%, S: 0.002%, Nb: 0.016%, V: 0.013%, Ti: 0.019%, Ca: 0.0021%, Al: 0.035%, and the balance is Fe and unavoidable impurities. The manufacturing method thereof comprises the following steps: (1) Smelting: Desulfurized molten iron is smelted in a converter or electric furnace, and then sent to refining for treatment. The high vacuum degassing time is 23 minutes, and the molten steel is purified by calcium treatment; (2) Casting: 320mm cross section was used for casting, and alternating electromagnetic stirring technology was applied. The electromagnetic stirring current was 380A and the frequency was 6.

0. The casting speed was 0.63m / min and the superheat was 12℃. After casting, the blank was pile-cooled for 48h. (3) Rolling: A two-stage rolling process was adopted, with a second rolling temperature of 893°C, a rolling speed of 2.0 m / s, a final reduction rate of 26% in the initial rolling process, a cooling roll speed of 0.2 m / s, an acceleration of 0.002 m / s², a red-return temperature of 630°C, and the steel plate was directly placed in the cooling pit for cooling, with a cooling time of 26 h. (4) Heat treatment: After the pile cooling, the steel plate is shot blasted and then subjected to normalizing heat treatment. The normalizing temperature is 909 ° C and the holding time is 360 min. After normalizing, the steel plate is water-cooled to 580 ° C and then air-cooled. (5) Warehousing: Sampling, marking, flaw detection and warehousing of heat-treated steel plates.

9. The method for manufacturing a thick steel plate for energy use according to claim 7, wherein: The steel plate has a thickness of 260 mm and its chemical composition and mass percentages include: C: 0.12%, Si: 0.27%, Mn: 1.68%, P: 0.014%, S: 0.001%, Nb: 0.017%, V: 0.027%, Ti: 0.022%, Ca: 0.0030%, Al: 0.041%, and the balance is Fe and unavoidable impurities. The manufacturing method thereof comprises the following steps: (1) Smelting: Desulfurized molten iron is smelted in a converter or electric furnace, and then sent to refining for treatment. The high vacuum degassing time is 24 minutes, and the molten steel is purified by calcium treatment; (2) Casting: 460mm cross section was used for casting, and alternating electromagnetic stirring technology was applied. The electromagnetic stirring current was 380A and the frequency was 6.

0. The casting speed was 0.50m / min and the superheat was 16℃. After casting, the blank was piled and cooled for 48h. (3) Rolling: A two-stage rolling process was adopted, with a second rolling temperature of 820°C, a rolling speed of 2.0 m / s, a final reduction rate of 29% in the initial rolling process, a cooling roll speed of 0.25 m / s, an acceleration of 0.001 m / s², a red-return temperature of 570°C, and the steel plate was directly placed in the cooling pit for cooling, with a cooling time of 29 h. (4) Heat treatment: After the pile cooling, the steel plate is shot blasted and then subjected to normalizing heat treatment. The normalizing temperature is 917 ° C and the holding time is 780 min / mm. After normalizing, the steel plate is water-cooled to 560 ° C and then air-cooled. (5) Warehousing: Sampling, marking, flaw detection and warehousing of heat-treated steel plates.

10. The method for manufacturing a thick steel plate for energy use according to claim 7, wherein: The thickness of the steel plate is 220 mm, and its chemical composition and mass percentage include: C: 0.11%, Si: 0.16%, Mn: 1.63%, P: 0.011%, S: 0.002%, Nb: 0.019%, V: 0.017%, Ti: 0.019%, Ca: 0.0031%, Al: 0.042%, N: 0.0030%, H: 0.00010; the balance is Fe and unavoidable impurities, and the manufacturing method thereof comprises the following steps: (1) Smelting: Desulfurized molten iron is smelted in a converter or electric furnace, and then sent to refining for treatment. The high vacuum degassing time is 26 minutes, and the molten steel is purified by calcium treatment; (2) Casting: 460mm cross section was used for casting, and alternating electromagnetic stirring technology was applied. The electromagnetic stirring current was 380A and the frequency was 6.

0. The casting speed was 0.50m / min and the superheat was 15℃. After casting, the blank was piled and cooled for 48h. (3) Rolling: A two-stage rolling process was adopted, with a second rolling temperature of 830°C, a rolling speed of 2.0 m / s, a final reduction rate of 27% in the initial rolling process, a cooling roll speed of 0.2 m / s, an acceleration of 0.001 m / s², a red-return temperature of 580°C, and the steel plate was directly placed in the cooling pit for cooling, with a cooling time of 29 h. (4) Heat treatment: After the pile cooling, the steel plate is shot blasted and then subjected to normalizing heat treatment. The normalizing temperature is 913 ° C and the holding time is 660 min / mm. After normalizing, the steel plate is water-cooled to 590 ° C and then air-cooled. (5) Warehousing: Sampling, marking, flaw detection and warehousing of heat-treated steel plates.

Images