Steel plate for welded bridges and its manufacturing method

Abstract

The present invention discloses a high-efficiency welded bridge steel and a manufacturing method thereof, which belongs to the technical field of steel production. The chemical composition and mass% of the steel are as follows: C: 0.05%-0.08%, Si: 0.10%-0.30%, Mn: 1.10%-1.50%, P≦0.015%, S≦0.0050%, Nb: 0.020%-0.040%, V: 0.0 10%~0.040%, Ti:0.006%~0.020%, Cr≦0.05%, Ni:0.10%~0.30%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al:0.025%~0.050%, Mg:0.0010%~0.0030%, N≦0.0050%, no Ca added, the rest are Fe and impurities. Through metallurgical technology, finely dispersed inclusions with magnesium oxide, magnesium sulfide and magnesium aluminum spinel as nuclei are produced, and TMCP rolling process and normalizing treatment are used to obtain ferrite and a small amount of pearlite structure with magnesium point as nucleation condition, improving the welding performance of bridge steel.

Description

[Technical Field]

[0001] The present invention relates to the technical field of steel production, and in particular to a high-efficiency welded bridge steel and a manufacturing method thereof. [Background technology]

[0002] With the development of China's economy, national infrastructure construction is becoming more and more perfect, and the construction of large bridges is reaching the world's highest level, making the quality of steel used in bridges increasingly strict. In the bridge construction process, steel materials need to be welded between steel members, and the quality of the welds has a significant impact on the quality of the entire bridge. Therefore, improving the weldability of bridge steel is of great significance to promote the development of the industry.

[0003] In the product application process, the factors that have a major impact on welding are the purity of the molten steel and the grain size of the steel sheet. Large inclusions will form large inclusions as impurity particles during the welding process, causing the weld area to fail inspection, and large ferrite grains in the steel sheet will cause further grain growth during the welding process, reducing the strength of the weld and the weld area, and adversely affecting the mechanical properties of the product. Summary of the Invention [Means for solving the problem]

[0004] In order to solve the above technical problems and overcome the shortcomings of the prior art, the present invention provides a high-efficiency welded bridge steel, whose chemical composition and mass % are as follows: C: 0.05%~0.08%, Si: 0.10%~0.30%, Mn: 1.10%~1.50%, P≦0.015%, S≦0.0050%, Nb: 0.020%~0.040%, V: 0.010%~0.040%, Ti: 0.006%~0.020%, Cr≦0.05%, Ni: 0.10%~0.30%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.025%~0.050%, Mg: 0.0010%~0.0030%, N≦0.0050%, no Ca added, the remainder is Fe and impurities.

[0005] (Technical Effects) The present invention adopts a low-carbon, high-manganese design, and simultaneously adds niobium, vanadium, and titanium alloys, which can effectively refine the grain size, promote the formation of ferrite phase, improve the strength and toughness of the product, and effectively improve the welding performance of the product.

[0006] Further technical solutions of the present invention are as follows:

[0007] The chemical composition and mass percentage of the high-efficiency welded bridge steel are as follows: C: 0.05% to 0.07%, Si: 0.10% to 0.20%, Mn: 1.10% to 1.30%, P≦0.014%, S≦0.0030%, Nb: 0.020% to 0.030%, V: 0.010% to 0.030%, Ti: 0.006% to 0.020%, Cr≦0.05%, Ni: 0.10% to 0.20%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.025% to 0.035%, Mg: 0.0010% to 0.0020%, N≦0.0050%, no Ca added, and the remainder being Fe and impurities.

[0008] The chemical composition and mass percentage of the high-efficiency welded bridge steel are as follows: C: 0.055% to 0.075%, Si: 0.15% to 0.25%, Mn: 1.20% to 1.40%, P≦0.013%, S≦0.0030%, Nb: 0.025% to 0.035%, V: 0.020% to 0.030%, Ti: 0.008% to 0.018%, Cr≦0.03%, Ni: 0.15% to 0.25%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.030% to 0.050%, Mg: 0.0015% to 0.0025%, N≦0.0050%, no Ca added, and the remainder being Fe and impurities.

[0009] The chemical composition and mass percentage of the high-efficiency welded bridge steel are as follows: C: 0.06% to 0.08%, Si: 0.20% to 0.30%, Mn: 1.30% to 1.50%, P≦0.012%, S≦0.0020%, Nb: 0.030% to 0.040%, V: 0.030% to 0.040%, Ti: 0.012% to 0.020%, Cr≦0.05%, Ni: 0.20% to 0.30%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.030% to 0.050%, Mg: 0.0015% to 0.0030%, N≦0.0050%, no Ca added, and the remainder being Fe and impurities.

[0010] Another object of the present invention is to provide a method for manufacturing high-efficiency welded bridge steel, S1. A rotary furnace or an electric furnace is used for smelting molten steel, and the steel is completely deoxidized during tapping, and the aluminum content at the rear of the furnace is 0.020%-0.050%; S2. LF is used for desulfurization and slag production, and alloying is performed based on the composition design, without magnesium alloying treatment; S3. Use RH or VD for vacuum treatment, and supply magnesium aluminum wire after vacuum treatment, with a magnesium content of 0.0020% to 0.0040%. After magnesium treatment, leave it to stir for 15 minutes; S4. To ensure smooth casting, a purge upper nozzle is used in continuous casting, the superheat is set to 15-35°C, and electromagnetic stirring and dynamic soft reduction processes are used; S5. After the billet surface inspection is passed, the billet is heated in a heating furnace. The austenitizing temperature is set to 1120±10°C, the heating time is 8-11 min / cm according to the billet thickness, and the soaking time is ≥ 30 min. S6. Rolling using a single-stand reversing rolling mill, with a second start rolling temperature of 800-980°C, a rolling finish temperature of 760-900°C, a soaking temperature of 750-850°C, and a self-tempering temperature of 600-700°C, and shearing the steel sheet after cooling to detect defects; S7. The steel plate is subjected to normalizing treatment, the normalizing temperature is 900 to 950 ° C, the heat retention time is 20 to 30 minutes, and the steel plate is air-cooled to room temperature after normalizing; S8. The method includes a step of inspecting the steel plate performance, inspecting the surface, and marking the steel plate, and then processing the steel plate for shipping.

[0011] In the manufacturing method of the high-efficiency welded steel for bridges, the steel plate structure is a ferrite structure with a small amount of pearlite.

[0012] The manufacturing method of the high-efficiency welded bridge steel is as follows: S1. Using a rotary furnace or electric furnace for smelting molten steel, the steel is completely deoxidized during tapping, and the aluminum content at the rear of the furnace is 0.033%-0.041%; S2. LF is used for desulfurization and slag production, and alloying is performed based on the composition design, without magnesium alloying treatment; S3. Use RH or VD for vacuum treatment, and supply magnesium aluminum wire after vacuum treatment, with a magnesium content of 0.0025% to 0.0033%. After magnesium treatment, leave it to stir for 15 minutes; S4. To ensure smooth casting, a purge upper nozzle is used in continuous casting, the superheat temperature is kept between 15 and 26°C, and electromagnetic stirring and dynamic soft reduction processes are used. S5. After the billet surface inspection is passed, the billet is heated in a heating furnace. The austenitizing temperature is set to 1120±10°C, the heating time is 8-11 min / cm according to the billet thickness, and the soaking time is ≥ 30 min. S6. Using a single-stand reversing rolling mill, the second start rolling temperature is 845-900°C, the rolling end temperature is 816-868°C, the soaking temperature is 798-826°C, and the self-tempering temperature is 636-682°C. After cooling the steel plate, the steel plate is sheared to detect defects. S7. Normalizing the steel plate, setting the normalizing temperature to 920-947°C, setting the heat retention time to 20-30 minutes, and air-cooling to room temperature after normalizing; S8. The method includes a step of inspecting the steel plate performance, inspecting the surface, and marking the steel plate, and then processing the steel plate for shipping. [Effects of the Invention]

[0013] The present invention has the following beneficial effects. (1) The present invention sets the composition of active elements such as magnesium, aluminum, and calcium, and effectively modifies the magnesium element inclusions, generating fine solid inclusions with magnesium oxide, magnesium sulfide, and magnesium aluminum spinel as nuclei. The fine inclusions act as austenitizing nuclei to generate particles, and after welding heat fusion, the fine particles hinder the growth of crystal grains, thereby avoiding strength loss due to welding. (2) The present invention adopts low-temperature austenitizing technology, which effectively reduces the original grain size, improves the uniformity and fineness of the steel plate grains after rolling, and greatly improves the strength and toughness of the product. (3) The present invention adopts a rolling cooling process, fully utilizes the structural phase change energy, and promotes the formation of a large amount of bainite through rapid cooling after rolling, eliminating the adverse effects of core bands in steel plates and playing a positive role in steel plate welding. (4) The present invention adopts a normalizing process to eliminate internal stress in the steel plate, improve the uniformity of the structure, and ensure the stability of internal stress after welding. The strength of the steel plate after welding is uniform, which effectively improves the product performance. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a metallographic structure diagram of a steel sheet according to Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Example 1 This example provides a high-efficiency welded bridge steel, whose chemical composition and mass percentage are as follows: C: 0.06%, Si: 0.130%, Mn: 1.15%, P: 0.011%, S: 0.0020%, Nb: 0.026%, V: 0.016%, Ti: 0.017%, Cr: 0.02%, Ni: 0.19%, Mo: 0.01%, Cu: 0.03%, B: 0.0002%, Al: 0.029%, Mg: 0.0023%, N: 0.00350%, no Ca added, and the remainder being Fe and impurities.

[0016] The manufacturing method is S1. A rotary furnace or an electric furnace is used for smelting molten steel, and the steel is completely deoxidized during tapping, and the aluminum content at the rear of the furnace is 0.041%; S2. LF is used for desulfurization and slag production, and alloying is performed based on the composition design, without magnesium alloying treatment; S3. Use RH or VD for vacuum treatment, and supply magnesium aluminum wire after vacuum treatment, and the magnesium content is 0.0033%. After magnesium treatment, the wire is left to stand and stirred for 15 minutes; S4. To ensure smooth casting, the continuous casting employs a purge upper nozzle, the superheat temperature is kept at 26°C, and electromagnetic stirring and dynamic soft reduction are used. S5. After the billet surface inspection is passed, the billet is heated in a step heating furnace, and the austenitizing temperature is set to 1129°C, the heating time is set to 10 min / cm according to the billet thickness, and the soaking time is set to 36 min; S6. Using a single-stand reversing rolling mill, the second start rolling temperature is 900°C, the rolling finish temperature is 868°C, the soaking temperature is 826°C, and the self-tempering temperature is 636°C. After cooling the steel plate, the steel plate is sheared to detect defects. S7. The steel plate is subjected to normalizing treatment, the normalizing temperature is 920°C, the heat retention time is 23 minutes, and the steel plate is air-cooled to room temperature after normalizing; S8. The method includes a step of inspecting the steel plate performance, inspecting the surface, and marking the steel plate, and then processing the steel plate for shipping.

[0017] Example 2 This example provides a high-efficiency welded bridge steel, which differs from Example 1 in the following respects: its chemical composition and mass % are as follows: C: 0.068%, Si: 0.23%, Mn: 1.35%, P: 0.011%, S: 0.00150%, Nb: 0.033%, V: 0.026%, Ti: 0.016%, Cr: 0.02%, Ni: 0.22%, Mo: 0.03%, Cu: 0.02%, B: 0.0001%, Al: 0.041%, Mg: 0.0021%, N: 0.0043%, no Ca added, and the remainder is Fe and impurities.

[0018] Example 3 This example provides a high-efficiency welded bridge steel, which differs from Example 1 in the following respects: its chemical composition and mass % are as follows: C: 0.073%, Si: 0.23%, Mn: 1.44%, P: 0.010%, S: 0.0010%, Nb: 0.036%, V: 0.033%, Ti: 0.016%, Cr: 0.02%, Ni: 0.27%, Mo: 0.02%, Cu: 0.02%, B: 0.0001%, Al: 0.039%, Mg: 0.0013%, N: 0.0029%, no Ca added, and the remainder is Fe and impurities.

[0019] According to the requirements of GB T 714-2008 structural steel standard for bridges, the physical and chemical tests of the materials were carried out, and the test results of the mechanical properties of the steel plates of Examples 1, 2 and 3 are shown in the table below.

[0020] [Table 1]

[0021] Based on the product design, this invention uses magnesium metallurgy technology to smelt pure steel, obtaining finely dispersed inclusions nucleated by magnesium oxide, magnesium sulfide, and magnesium aluminum spinel. These fine inclusions act as austenite nuclei in the steel to generate particles, refining the original austenite grain boundaries. Through the rolling process, a uniform and fine microstructure is obtained, as shown in Figure 1. This solves the problem of softening of the welded area and heat-affected zone due to high temperatures during the welding process, improves the toughness of the product, significantly improves the welding performance of the product, and ensures the use performance of the steel for bridges.

[0022] In addition to the above embodiments, the present invention may have other embodiments, and the technical solutions formed by equivalent substitution or equivalent modification shall all fall within the protection scope of the present invention.

[0023] (Addendum) (Appendix 1) The chemical composition and mass percentages are as follows: C: 0.05% to 0.08%, Si: 0.10% to 0.30%, Mn: 1.10% to 1.50%, P≦0.015%, S≦0.0050%, Nb: 0.020% to 0.040%, V: 0.010% to 0.040%, Ti: 0.006% to 0.020%, Cr≦0.05%, Ni: 0.10% to 0.30%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.025% to 0.050%, Mg: 0.0010% to 0.0030%, N≦0.0050%, no Ca added, the remainder being Fe and impurities. High-efficiency welded bridge steel characterized by:

[0024] (Appendix 2) The chemical composition and mass percentages are as follows: C: 0.05% to 0.07%, Si: 0.10% to 0.20%, Mn: 1.10% to 1.30%, P≦0.014%, S≦0.0030%, Nb: 0.020% to 0.030%, V: 0.010% to 0.030%, Ti: 0.006% to 0.020%, Cr≦0.05%, Ni: 0.10% to 0.20%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.025% to 0.035%, Mg: 0.0010% to 0.0020%, N≦0.0050%, no Ca added, the remainder being Fe and impurities. 2. High-efficiency welded steel for bridges according to claim 1, characterized in that

[0025] (Appendix 3) The chemical composition and mass percentages are as follows: C: 0.055% to 0.075%, Si: 0.15% to 0.25%, Mn: 1.20% to 1.40%, P≦0.013%, S≦0.0030%, Nb: 0.025% to 0.035%, V: 0.020% to 0.030%, Ti: 0.008% to 0.018%, Cr≦0.03%, Ni: 0.15% to 0.25%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.030% to 0.050%, Mg: 0.0015% to 0.0025%, N≦0.0050%, no Ca added, the remainder being Fe and impurities. 2. High-efficiency welded steel for bridges according to claim 1, characterized in that

[0026] (Appendix 4) The chemical composition and mass percentages are as follows: C: 0.06% to 0.08%, Si: 0.20% to 0.30%, Mn: 1.30% to 1.50%, P≦0.012%, S≦0.0020%, Nb: 0.030% to 0.040%, V: 0.030% to 0.040%, Ti: 0.012% to 0.020%, Cr≦0.05%, Ni: 0.20% to 0.30%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.030% to 0.050%, Mg: 0.0015% to 0.0030%, N≦0.0050%, no Ca added, the remainder being Fe and impurities. 2. High-efficiency welded steel for bridges according to claim 1, characterized in that

[0027] (Appendix 5) Applies to any one of Appendices 1 to 4, S1. A rotary furnace or an electric furnace is used for smelting molten steel, and the steel is completely deoxidized during tapping, and the aluminum content at the rear of the furnace is 0.020%-0.050%; S2. LF is used for desulfurization and slag production, and alloying is performed based on the composition design, without magnesium alloying treatment; S3. Use RH or VD for vacuum treatment, and supply magnesium aluminum wire after vacuum treatment, with a magnesium content of 0.0020% to 0.0040%. After magnesium treatment, leave it to stir for 15 minutes; S4. To ensure smooth casting, a purge upper nozzle is used in continuous casting, the superheat temperature is kept between 15 and 35°C, and electromagnetic stirring and dynamic soft reduction are used. S5. After the billet surface inspection is passed, the billet is heated in a heating furnace. The austenitizing temperature is set to 1120±10°C, the heating time is set to 8-11 min / cm according to the billet thickness, and the soaking time is ≥ 30 min. S6. Rolling using a single-stand reversing rolling mill, with a second start rolling temperature of 800-980°C, a rolling finish temperature of 760-900°C, a soaking temperature of 750-850°C, and a self-tempering temperature of 600-700°C, and shearing the steel sheet after cooling to detect defects; S7. The steel plate is subjected to normalizing treatment, the normalizing temperature is 900 to 950 ° C, the heat retention time is 20 to 30 minutes, and the steel plate is air-cooled to room temperature after normalizing; S8. Steel plate performance inspection, surface inspection, marking and shipping processing step. A method for manufacturing highly efficient welded bridge steel.

[0028] (Appendix 6) The steel sheet structure is ferrite and a small amount of pearlite. 6. A method for producing a highly efficient welded steel for bridges according to claim 5.

[0029] (Appendix 7) S1. Using a rotary furnace or electric furnace for smelting molten steel, the steel is completely deoxidized during tapping, and the aluminum content at the rear of the furnace is 0.033%-0.041%; S2. LF is used for desulfurization and slag production, and alloying is performed based on the composition design, without magnesium alloying treatment; S3. Use RH or VD for vacuum treatment, and supply magnesium aluminum wire after vacuum treatment, with a magnesium content of 0.0025% to 0.0033%. After magnesium treatment, leave it to stir for 15 minutes; S4. To ensure smooth casting, a purge upper nozzle is used in continuous casting, the superheat temperature is kept between 15 and 26°C, and electromagnetic stirring and dynamic soft reduction processes are used. S5. After the billet surface inspection is passed, the billet is heated in a heating furnace. The austenitizing temperature is set to 1120±10°C, the heating time is 8-11 min / cm according to the billet thickness, and the soaking time is ≥ 30 min. S6. Using a single-stand reversing rolling mill, the second start rolling temperature is 845-900°C, the rolling end temperature is 816-868°C, the soaking temperature is 798-826°C, and the self-tempering temperature is 636-682°C. After cooling the steel plate, the steel plate is sheared to detect defects. S7. Normalizing the steel plate, setting the normalizing temperature to 920-947°C, setting the heat retention time to 20-30 minutes, and air-cooling to room temperature after normalizing; S8. Steel plate performance inspection, surface inspection, marking and shipping processing step. 6. A method for producing a highly efficient welded steel for bridges according to claim 5.

Claims

1. The chemical composition and mass % are as follows: C: 0.05% to 0.08%, Si: 0.10% to 0.30%, Mn: 1.10% to 1.50%, P≦0.015%, S≦0.0050%, Nb: 0.020% to 0.040%, V: 0.010% to 0.040%, Ti: 0.006% to 0.020%, Cr≦0.05%, Ni: 0.10% to 0.30%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.025% to 0.050%, Mg: 0.0010% to 0.0030%, N≦0.0050%, no Ca was added, and the remainder was Fe and impurities. having inclusions cored with magnesium oxide, magnesium sulfide and magnesium aluminum spinel; A steel plate for welded bridges characterized by:

2. The chemical composition and mass % are as follows: C: 0.05% to 0.07%, Si: 0.10% to 0.20%, Mn: 1.10% to 1.30%, P≦0.014%, S≦0.0030%, Nb: 0.020% to 0.030%, V: 0.010% to 0.030%, Ti: 0.006% to 0.020%, Cr≦0.05%, Ni: 0.10% to 0.20%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.025% to 0.035%, Mg: 0.0010% to 0.0020%, N≦0.0050%, no Ca was added, and the remainder was Fe and impurities. The steel plate for welded bridges according to claim 1.

3. The chemical composition and mass percentages are as follows: C: 0.055% to 0.075%, Si: 0.15% to 0.25%, Mn: 1.20% to 1.40%, P≦0.013%, S≦0.0030%, Nb: 0.025% to 0.035%, V: 0.020% to 0.030%, Ti: 0.008% to 0.018%, Cr≦0.03%, Ni: 0.15% to 0.25%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.030% to 0.050%, Mg: 0.0015% to 0.0025%, N≦0.0050%, no Ca was added, and the remainder was Fe and impurities. The steel plate for welded bridges according to claim 1.

4. The chemical composition and mass percentages are as follows: C: 0.06% to 0.08%, Si: 0.20% to 0.30%, Mn: 1.30% to 1.50%, P≦0.012%, S≦0.0020%, Nb: 0.030% to 0.040%, V: 0.030% to 0.040%, Ti: 0.012% to 0.020%, Cr≦0.05%, Ni: 0.20% to 0.30%, Mo≦0.05%, Cu≦0.05%, B≦0.0005%, Al: 0.030% to 0.050%, Mg: 0.0015% to 0.0030%, N≦0.0050%, no Ca was added, and the remainder was Fe and impurities. The steel plate for welded bridges according to claim 1.

5. Applicable to any one of claims 1 to 4, S1. Using a rotary furnace or electric furnace for smelting molten steel, the steel is completely deoxidized during steel tapping, and the aluminum content at the rear of the furnace is 0.020%-0.050%; S2. Using LF for desulfurization and slag production, alloying based on composition design, and not performing magnesium alloying treatment; S3. RH or VD is used for the vacuum treatment, and after the vacuum treatment is completed, a magnesium aluminum wire is supplied, and the magnesium content is 0.0020% to 0.0040%, and after the magnesium treatment is completed, the wire is left to stand and stirred for 15 minutes; S4. To ensure smooth casting, the continuous casting employs a purge upper nozzle, the superheat degree is 15-35°C, and electromagnetic stirring and dynamic soft reduction process are used; S5. After the billet surface inspection is passed, the billet is heated in a heating furnace, the austenitizing temperature is set to 1120±10°C, the heating time is set to 8-11 min / cm according to the billet thickness, and the soaking time is ≥ 30 min; S6. Rolling using a single stand reversing rolling mill, with a second start rolling temperature of 800-980°C, a rolling finish temperature of 760-900°C, a water soaking temperature for cooling of 750-850°C, and a self-tempering temperature of 600-700°C, and shearing the steel sheet after cooling to detect flaws; S7. Normalizing the steel sheet, setting the normalizing temperature to 900 to 950°C, setting the temperature retention time to 20 to 30 minutes, and air-cooling to room temperature after normalizing; S8. A step of inspecting the steel plate performance, inspecting the surface, and marking the steel plate and then shipping the steel plate, Steps S1 to S8 are performed in numerical order. A method for manufacturing a steel plate for welded bridges, characterized by the above.

6. S1. Using a rotary furnace or electric furnace for smelting molten steel, the steel is completely deoxidized during steel tapping, and the aluminum content at the rear of the furnace is 0.033%-0.041%; S2. Using LF for desulfurization and slag production, alloying based on composition design, and not performing magnesium alloying treatment; S3. RH or VD is used for the vacuum treatment, and after the vacuum treatment is completed, a magnesium aluminum wire is supplied, and the magnesium content is 0.0025% to 0.0033%, and after the magnesium treatment is completed, the wire is left to stand and stirred for 15 minutes; S4. To ensure smooth casting, the continuous casting employs a purge upper nozzle, the superheat degree is 15-26°C, and electromagnetic stirring and dynamic soft reduction process are used; S5. After the billet surface inspection is passed, the billet is heated in a heating furnace, the austenitizing temperature is set to 1120±10°C, the heating time is set to 8-11 min / cm according to the billet thickness, and the soaking time is ≥ 30 min; S6. Rolling using a single stand reversing rolling mill, with a second start rolling temperature of 845-900°C, a rolling finish temperature of 816-868°C, a water soaking temperature of 798-826°C, and a self-tempering temperature of 636-682°C, and shearing the steel sheet after cooling to detect defects; S7. A step of normalizing the steel sheet, setting the normalizing temperature to 920 to 947°C, setting the heat retention time to 20 to 30 minutes, and air-cooling to room temperature after normalizing; S8. A step of inspecting the steel plate performance, inspecting the surface, and marking the steel plate and then shipping the steel plate. The method for manufacturing a steel plate for a welded bridge according to claim 5.

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