Preparation method of continuous casting slab for low compression ratio Q345R super-thick container steel

Abstract

The application discloses a preparation method of a continuous casting slab for a low-compression-ratio Q345R super-thick container steel, and relates to the technical field of steel smelting, wherein the pressing mode in the continuous casting process is composed of light pressing and convex roller heavy pressing. The method adopts light pressing and two-cooling electric stirring to improve center segregation and eliminate intermediate cracks, and the convex roller heavy pressing eliminates center loose defects; the internal quality of the low-compression-ratio ultrasonic detection qualified super-thick plate is effectively improved, and the ultrasonic detection qualified rate of the low-compression-ratio ultrasonic detection qualified super-thick plate is controlled to be above 96%. The super-thick plate produced by the method has good effects after implementation, and can meet the use requirements of low-cost, high-efficiency production of high-quality super-thick container steel.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of steel smelting, and particularly relates to a preparation method of a low-compression-ratio Q345R super-thick container steel continuous casting slab. BACKGROUND

[0002] With the rapid development of the petroleum and chemical industry in China, the design and manufacturing of pressure vessels are developing towards large thickness and high parameterization, which puts forward higher requirements for the safety of pressure vessels and more stringent requirements for the performance and specifications of steel plates for manufacturing pressure vessels. As a pressure vessel steel, Q345R is equivalent to SA516Gr70 in ASME A516 / SA516M-2017, and is widely used for manufacturing large equipment for serving in harsh environments such as petroleum and chemical industry due to its good low-temperature impact performance and process performance. At present, high-quality super-thick pressure vessel steels are generally produced by using die-casting ingots, forged blanks or even composite blanks, but the yield rate is low and the cost is high. Therefore, directly using 400mm or more continuous casting slabs for production is the best way to improve the yield rate and reduce the cost.

[0003] A low-compression-ratio super-thick container plate production process is disclosed in the related art, which adopts a 250mm*2300mm cross-section slab continuous casting machine for casting, adopts a light pressing-down process for the casting machine during the casting process, adopts a high-temperature low-speed large-pressing-down rolling process for rolling, and the final thickness of the steel plate is 100mm and the compression ratio is 2.5. The compression ratio of the application is low, but the thickness of the blank limits the final thickness of the steel plate. In addition, the high-temperature low-speed large-pressing-down rolling process has high requirements for the rolling capacity of the rolling mill, and it is difficult to realize stable batch rolling.

[0004] A large-thickness low-temperature pressure vessel steel plate and a manufacturing method thereof are also disclosed in the related art. In the continuous casting step, electromagnetic stirring and heavy pressing-down are used, the pressing-down amount of the heavy pressing-down is 15mm-25mm, the pulling speed is 0.4m / min-0.6m / min, the intermediate ladle steel water superheat degree is controlled to be ≤25℃, and finally a super-thick high-quality continuous casting slab with a thickness of more than 375mm is obtained; in the rolling step, the total compression ratio of rolling is ≥6.0. The thickness specification of the steel plate involved in the method is only 48mm-60mm.

[0005] A low-carbon high-toughness super-thick steel plate and a manufacturing method thereof are also disclosed in the related art. The thickness of the low-carbon high-toughness steel plate manufactured by using a continuous casting slab with a thickness of 370mm or more can reach 100mm-110mm. The total compression ratio of rolling required by the method is ≥3.

[0006] A production method of a super-thick steel plate is also disclosed in the related art. A high-performance 60mm-100mm thick Q345R steel plate is produced by using a continuous casting slab, the production cost is reduced, and the requirements of high-parameter pressure vessel manufacturing are met. The thickness specification of the steel plate involved in the method is only 60mm-100mm.

[0007] The related art also discloses a kind of excellent low temperature toughness super thick alloy steel plate and its preparation method, using annealed continuous casting billet as base billet to carry out three billets compound, compound billet thickness > 900mm, using vacuum electron beam welding, compound billet heating, rolling and quenching + tempering heat treatment, produce the alloy steel plate for thick pressure vessel with thickness 210mm.The manufacturing method has the advantages of short process, simple process, high yield, low cost, short production cycle and high efficiency;The mechanical properties of the steel plate meet: core transverse impact single value ≥200J, thickness direction section shrinkage rate ≥60%, and the ultrasonic flaw detection of the steel plate meets the highest level requirement of NB / T47013.3.The method uses compound billet rolling to produce alloy steel plate for thick pressure vessel, and the production cost is high.

[0008] According to the above disclosed method, it can be found that the preparation method of the low compression ratio, high quality Q345R super thick container steel continuous casting billet has the following problems:

[0009] 1. Only rely on rolling, without playing the advantage of continuous casting;

[0010] 2. The continuous casting process parameters are not disclosed;

[0011] 3. Low yield, high cost, long production cycle and low production efficiency;

[0012] 4. Small product thickness, etc. SUMMARY

[0013] The purpose of the present application is to provide a preparation method of low compression ratio Q345R super thick container steel continuous casting billet, to solve at least one aspect of the problems and defects in the above background art.

[0014] Specifically, the present application provides a preparation method of low compression ratio Q345R super thick container steel continuous casting billet, comprising the following steps:

[0015] After continuous casting of molten steel, continuous casting billet is prepared;

[0016] The reduction mode in the continuous casting process is composed of light reduction and convex roller heavy reduction;

[0017] The light reduction interval starts from 23.5m to 25.5m away from the outlet of the crystallizer, and ends at 30m to 31m away from the outlet of the crystallizer, and the length of the light reduction interval is 4.5m to 7.5m;

[0018] The total reduction amount of light reduction is 12mm to 15mm;

[0019] The total reduction amount of light reduction is distributed according to the reduction rate of 2.0mm / m to 2.5mm / m;

[0020] The convex roller large reduction interval starts from 34m to 36m away from the crystallizer outlet and ends at 36m to 38m away from the crystallizer outlet, and the length of the convex roller large reduction interval is 2m to 4m;

[0021] The total reduction of the convex roller large reduction is 8mm to 10mm;

[0022] The convex roller large reduction is distributed according to a reduction rate of 3.5mm / m to 4.5mm / m;

[0023] The secondary cooling electric stirring is used in the continuous casting process.

[0024] According to the preparation method of the present application, at least the following beneficial effects are achieved:

[0025] The present application mainly uses the light reduction technology, the secondary cooling electric stirring technology and the convex large reduction technology to improve the center segregation of the high-quality thick slab for pressure vessels, eliminate the intermediate cracks and reduce the center porosity, thereby providing conditions for producing the low-compression-ratio ultrasonic inspection thick plate.

[0026] The method of the present application uses the light reduction technology, the secondary cooling electric stirring technology and the convex large reduction technology to improve the internal quality of the thick slab, improve the center segregation and the center porosity of the thick slab, and eliminate the intermediate cracks; under the target of producing the thick plate, the internal quality of the low-compression-ratio ultrasonic inspection thick plate is effectively improved, and the ultrasonic inspection qualified rate of the low-compression-ratio ultrasonic inspection thick plate is controlled to be above 96%.

[0027] The thick slab produced by the method has good effect after implementation, and can meet the use requirements of low-cost and high-efficiency production of high-quality thick steel for pressure vessels.

[0028] According to some embodiments of the present application, the preparation method is suitable for the preparation of a continuous casting slab for a thick container steel with a thickness of 100mm or more.

[0029] According to some embodiments of the present application, the preparation method is suitable for the preparation of a continuous casting slab for a thick container steel with a thickness of 150mm or more.

[0030] According to some embodiments of the present application, the secondary cooling electric stirring is composed of two pairs of two-section roller stirrers.

[0031] According to some embodiments of the present application, the superheat degree of the molten steel is 7℃ to 20℃.

[0032] According to some embodiments of the present application, the thickness of the continuous casting slab is 439mm to 441mm.

[0033] According to some embodiments of the present application, the rolling speed of the light rolling is 0.025 mm / s.

[0034] According to some embodiments of the present application, the rolling speed of the large rolling of the convex roller is 0.025 mm / s.

[0035] According to some embodiments of the present application, the drawing speed during the light rolling is 0.425 m / min to 0.475 m / min.

[0036] According to some embodiments of the present application, the drawing speed during the large rolling of the convex roller is 0.425 m / min to 0.475 m / min.

[0037] According to some embodiments of the present application, the low compression ratio is 2.9 to 3.1.

[0038] According to some embodiments of the present application, the two pairs of two-section roller mixers are respectively installed at the inlet and outlet of the fourth sector.

[0039] According to some embodiments of the present application, the two pairs of two-section roller mixers are respectively installed at the inlet and outlet of the fourth sector.

[0040] According to some embodiments of the present application, the two pairs of two-section roller mixers are respectively installed at the inlet and outlet of the fourth sector.

[0041] According to some embodiments of the present application, the two pairs of two-section roller mixers are respectively installed at the inlet and outlet of the fourth sector.

[0042] According to some embodiments of the present application, the two pairs of two-section roller mixers are respectively installed at the inlet and outlet of the fourth sector.

[0043] According to some embodiments of the present application, the two pairs of two-section roller mixers are respectively installed at the inlet and outlet of the fourth sector. DETAILED DESCRIPTION

[0044] The concept and the technical effects of the present application will be described below in combination with embodiments, so as to fully understand the purposes, features and effects of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0045] In the description of the application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in one or more embodiments or examples.

[0046] Unless otherwise specified, the specific conditions in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are conventional products that can be obtained by commercial purchase, unless otherwise specified.

[0047] The preparation method of the continuous casting slab of the low-compression-ratio Q345R thick pressure vessel steel in the embodiment of the application is as follows:

[0048] (1) In the continuous casting process, a 473 mm x 2600 mm cross-section straight mold continuous bending continuous straightening arc continuous casting machine is used for production, the arc radius is 12 m, and the control casting speed is 0.425 m / min to 0.475 m / min.

[0049] (2) The light pressing down technology is used:

[0050] The total amount of the basic roll gap shrinkage of the arc section (fan sections 1-7) and the straightening section (fan sections 8-9) in the light pressing down process is 2.75 mm; the light pressing down interval starts from 23.5 m to 25.5 m away from the outlet of the mold, and ends at 30 m to 31 m away from the outlet of the mold, the pressing down rate is 0.025 mm / s, the light pressing down interval length is 4.5 m to 7.5 m, the light pressing down rate is distributed according to 2.0 mm / m to 2.5 mm / m, and the total light pressing down amount is 12 mm to 15 mm.

[0051] (3) The convex roller large pressing down technology is used:

[0052] The convex roller large pressing down interval starts from 34 m to 36 m away from the outlet of the mold, and ends at 36 m to 38 m away from the outlet of the mold, the convex roller large pressing down interval length is 2 m to 4 m, the pressing down rate is 0.025 mm / s, the casting speed is 0.425 m / min to 0.475 m / min during pressing down, the total pressing down amount is 8 mm to 10 mm, and the pressing down rate is distributed according to 3.5 mm / m to 4.5 mm / m.

[0053] (4) The two-cooling electric stirring technology is used:

[0054] The secondary cooling electric stirring is composed of two pairs of two-section roller stirrers, which are respectively installed at the inlet and outlet of the fourth segment; the alternating stirring mode is adopted, forward 15s-25s, stop 1s-5s, reverse 15-25s; the current intensity is 500-650A at the inlet and 500-650A at the outlet; and the electric stirring frequency is 4Hz-6Hz.

[0055] The mass fraction of each element in the slab in the embodiment of the application is as follows:

[0056] C=0.14-0.15, Si=0.20-0.30, Mn=1.52-1.58, P≤0.012, S≤0.003, Alt=0.02-0.050, Nb=0.035-0.040, Ti=0.012-0.020, Cr=0.20-0.25, Ni=0.15-0.20, Cu=0.15-0.20, and the rest is Fe and residual elements.

[0057] Example 1

[0058] The embodiment is a preparation method of a continuous casting slab for a low compression ratio high-quality Q345R special thick pressure container steel, the compression ratio is 2.91, and the specific process is as follows:

[0059] The slab for the Q345R container steel is produced by continuous casting, the cross-sectional size of the slab is 2500mm*440mm, the casting speed of the continuous casting machine is 0.45m / min, the casting speed is kept stable and unchanged, the superheat degree of the molten steel in the tundish is 7-15℃, the light pressing-down technology and the convex roller large pressing-down technology are adopted for control, and the pressing-down speed is 0.025mm / s.

[0060] The light pressing-down interval (carried out in the horizontal section) starts from 24.0m away from the outlet of the crystallizer and ends at 31.0m away from the outlet of the crystallizer, the pressing-down speed is 0.025mm / s, the length of the light pressing-down interval is 7.0m, the light pressing-down amount is distributed according to the pressing-down rate 2.14mm / m, and the total light pressing-down amount is 15mm.

[0061] The convex roller large pressing-down interval starts from 34m away from the outlet of the crystallizer and ends at 36m away from the outlet of the crystallizer, the length of the convex roller large pressing-down interval is 2m, the pressing-down speed is 0.025mm / s, the total pressing-down amount is 9mm, and the total pressing-down amount is distributed according to the pressing-down rate 4.5mm / m.

[0062] The secondary cooling electric stirring technology is adopted: the secondary cooling electric stirring is composed of two pairs of two-section roller stirrers, which are respectively installed at the inlet and outlet of the fourth segment; the alternating stirring mode is adopted, forward 18s, stop 3s, reverse 18s; the current intensity is 550A at the inlet and 550A at the outlet; and the electric stirring frequency is 6Hz.

[0063] After casting, the internal quality of the Q345R container steel casting blank was subjected to macroscopic inspection (People's Republic of China Black Metallurgy Industry Standard “Macrostructure Defect Rating Chart for Continuous Casting Steel Slab” YB / T 4003-2016), and the inspection results showed that the incidence of transverse macroscopic intermediate cracks of the casting blank was reduced from 80% to 0% (relative to Comparative Example 1), the proportion of center porosity defects rated as 1.0 level was increased from 65% to 100%, and the proportion of center segregation ≤C1.0 level was increased from 50% to 100%.

[0064] Example 2

[0065] The present example is a preparation method of a continuous casting slab of a low compression ratio, high-quality Q345R steel for extra-thick pressure vessels, and the compression ratio is 2.94, and the specific process is as follows:

[0066] The Q345R container steel slab with a cross-sectional size of 2070mm x 444mm was produced by continuous casting, the casting speed of the continuous casting machine was 0.45m / min, and the casting speed was kept stable and unchanged, and the superheat of the molten steel in the tundish was 10℃-15℃;

[0067] Light pressing down technology and convex roller large pressing down technology were adopted, and the pressing down rate was 0.025mm / s; the light pressing down interval started from 23.5m away from the outlet of the crystallizer and ended at 28.5m away from the outlet of the crystallizer, the pressing down rate was 0.025mm / s, the length of the light pressing down interval was 5m, and the light pressing down amount was distributed according to the pressing down rate of 2.4mm / m, and the total light pressing down amount was 12mm;

[0068] The convex roller large pressing down interval started from 36m away from the outlet of the crystallizer and ended at 38m away from the outlet of the crystallizer, the length of the convex roller large pressing down interval was 2m, the pressing down rate was 0.025mm / s, the total pressing down amount was 8mm, and the pressing down amount was distributed according to the pressing down rate of 4mm / m.

[0069] Two-cooling electric stirring technology was adopted: the two-cooling electric stirring was composed of two pairs of two-section roller stirrers, which were installed at the inlet and outlet of the 4th segment, respectively; an alternating stirring mode was adopted, forward for 20s, stop for 2s, and reverse for 20s; the current intensity was 600A at the inlet and 650A at the outlet; and the electric stirring frequency was 5Hz.

[0070] After casting, the internal quality of the Q345R container steel casting blank was subjected to macroscopic inspection (People's Republic of China Black Metallurgy Industry Standard “Macrostructure Defect Rating Chart for Continuous Casting Steel Slab” YB / T 4003-2016), and the inspection results showed that the incidence of transverse macroscopic intermediate cracks of the casting blank was reduced from 80% to 0% (relative to Comparative Example 1), the proportion of center porosity defects rated as 1.0 level was increased from 65% to 100%, and the proportion of center segregation ≤C1.0 level was increased from 50% to 100%.

[0071] Example 3

[0072] The embodiment is a preparation method of a continuous casting slab for a low compression ratio high-quality Q345R special thick pressure container steel, the compression ratio is 2.92, and the specific process is as follows:

[0073] The slab for the Q345R container steel is produced by continuous casting, the casting speed of the continuous casting machine is 0.45 m / min, the casting speed is kept stable and unchanged, and the superheat of the molten steel in the tundish is 10℃-18℃.

[0074] The light pressing down technology and the convex roller large pressing down technology are adopted, the pressing down speed is 0.025 mm / s; the light pressing down interval starts from the position 24.5 m away from the outlet of the crystallizer and ends at the position 31.3 m away from the outlet of the crystallizer, the pressing down speed is 0.025 mm / s, the length of the light pressing down interval is 6.8 m, the light pressing down amount is distributed according to the pressing down rate 2.2 mm / m, and the total light pressing down amount is 15 mm.

[0075] The convex roller large pressing down interval starts from the position 36 m away from the outlet of the crystallizer and ends at the position 38 m away from the outlet of the crystallizer, the length of the convex roller large pressing down interval is 2 m, the pressing down speed is 0.025 mm / s, the total pressing down amount is 8 mm, and the total pressing down amount is distributed according to the pressing down rate 4 mm / m.

[0076] The two-cooling electric stirring technology is adopted: the two-cooling electric stirring is composed of two pairs of two-section roller stirrers, which are respectively installed at the inlet and outlet of the fourth segment fan-shaped segment; the alternating stirring mode is adopted, the forward direction is 20 s, the stop is 2 s, and the reverse direction is 20 s; the current intensity is 500 A at the inlet and 550 A at the outlet; and the electric stirring frequency is 5 Hz.

[0077] After the casting is completed, the internal quality of the Q345R container steel cast slab is subjected to macro examination (the People's Republic of China Black Metallurgy Industry Standard “Macrostructure Defect Rating Chart for Continuous Casting Slabs” YB / T 4003-2016), and the inspection result shows that the incidence of transverse macro cracks in the slab is reduced from 80% to 0% (relative to the comparative example 1), the proportion of the center porosity defect rating is increased from 65% to 100%, and the proportion of the center segregation ≤C1.0 level is increased from 50% to 100%.

[0078] Comparative example 1

[0079] The comparative example is a preparation method of a continuous casting slab for a Q345R special thick pressure container steel, the compression ratio is 3.12, and the specific process is as follows:

[0080] The slab for Q345R vessel steel with a cross-sectional size of 2270 mm x 440 mm is produced by continuous casting at a casting speed of 0.45 m / min, and the casting speed is kept unchanged, and the molten steel overheat degree in the tundish is 8-15 DEG C; the large reduction at the solidification end is adopted for control, and the reduction rate is 0.025 mm / s;

[0081] The reduction interval starts from 24.5 m away from the mold outlet to 35.7 m away from the mold outlet, the reduction rate is 0.025 mm / s, the length of the reduction interval is 11.2 m, the single reduction amount of the 13th section is 10 mm, the reduction rate of the 13th section is 5 mm / m, and the total large reduction amount is 24 mm.

[0082] After casting, the internal quality of the Q345R vessel steel slab is inspected by macro examination (YB / T 4003-2016, "Macrostructure Defect Rating Chart for Continuous Casting Slab", the black metallurgical industry standard of the People's Republic of China), and the inspection results show that the occurrence rate of transverse macro intermediate cracks of the slab is 80%, the proportion of the center porosity defect rating of 1.0 level is 65%, and the proportion of the center segregation of ≤C1.0 level is 50%.

[0083] Comparative Example 2

[0084] The present comparative example is a preparation method of a continuous casting slab for a Q345R thick pressure vessel steel, and the compression ratio is 3.2, and the specific process is as follows:

[0085] The slab for Q345R vessel steel with a cross-sectional size of 2070 mm x 452 mm is produced by continuous casting at a casting speed of 0.45 m / min, and the casting speed is kept unchanged, and the molten steel overheat degree in the tundish is 9-14 DEG C; the light reduction is adopted for control, and the reduction rate is 0.025 mm / s;

[0086] The reduction interval starts from 24.5 m away from the mold outlet to 31.3 m away from the mold outlet, the reduction rate is 0.025 mm / s, the length of the reduction interval is 6.8 m, the single reduction amount of the 12th section is 5 mm, the reduction rate of the 12th section is 2.5 mm / m, and the total light reduction amount is 12 mm.

[0087] After casting, the internal quality of the Q345R vessel steel slab is inspected by macro examination (YB / T 4003-2016, "Macrostructure Defect Rating Chart for Continuous Casting Slab", the black metallurgical industry standard of the People's Republic of China), and the inspection results show that the occurrence rate of transverse macro intermediate cracks of the slab is 50%, the proportion of the center porosity defect rating of 1.0 level is 45%, and the proportion of the center segregation of ≤C1.0 level is 55%.

[0088] In summary, the present application is mainly through the thick slab continuous casting light pressing technology, the second cold electric stirring technology, the convex large pressing technology and other technical measures to improve the center segregation of high quality thick pressure vessel steel continuous casting slab, eliminate the intermediate crack, reduce the center porosity and other defects, provide conditions for the production of low compression ratio NDT thick plate. The method of the present application uses light pressing technology, second cold electric stirring technology, convex large pressing technology to improve the internal quality of thick slab, improve the center segregation and center porosity defects of thick slab, and eliminate the intermediate crack; under the target of producing thick plate, effectively improve the internal quality of low compression ratio NDT thick plate, and control the flaw detection qualified rate of low compression ratio NDT thick plate to be more than 96%. The thick slab produced by the method has good effect after implementation, which can meet the use requirements of low-cost and high-efficiency production of high-quality thick pressure vessel steel.

[0089] The above specific embodiments further illustrate the purpose, technical solutions and advantages of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for producing a continuously cast slab for a low compression ratio Q345R super-thick vessel steel, characterized in that, It comprises the following steps: After continuous casting of the molten steel, a continuous casting slab is prepared; The press-down mode in the continuous casting process is composed of light press-down and convex roll heavy press-down; The light press-down interval starts from 23.5m to 25.5m away from the outlet of the crystallizer and ends at 30m to 31m away from the outlet of the crystallizer, with a length of 4.5m to 7.5m; The total light press-down amount is 12mm to 15mm; The total light press-down amount is distributed according to a press-down rate of 2.0mm / m to 2.5mm / m; The convex roll heavy press-down interval starts from 34m to 36m away from the outlet of the crystallizer and ends at 36m to 38m away from the outlet of the crystallizer, with a length of 2m to 4m; The total convex roll heavy press-down amount is 8mm to 10mm; The convex roll heavy press-down is distributed according to a press-down rate of 3.5mm / m to 4.5mm / m; The two-cool electric stirring is used in the continuous casting process; The pulling speed during the light press-down is 0.425m / min to 0.475m / min; The pulling speed during the convex roll heavy press-down is 0.425m / min to 0.475m / min.

2. The method for manufacturing a continuously cast slab for a low compression ratio Q345R super-thick vessel steel according to claim 1, characterized in that, The superheat of the molten steel is 7℃ to 20℃.

3. The method for manufacturing a continuously cast slab for a low compression ratio Q345R super-thick vessel steel according to claim 1, characterized in that, The thickness of the continuous casting slab is 439mm to 441mm.

4. The method for producing a continuously cast slab for a low compression ratio Q345R super thick vessel steel according to claim 1, characterized in that, The low compression ratio is 2.9 to 3.

1.

5. The method of producing a continuously cast slab for a low compression ratio Q345R super thick vessel steel according to claim 1, characterized in that, The two-cool electric stirring uses an alternating stirring mode, with a forward direction of 15s to 25s, a stop of 1s to 5s, and a reverse direction of 15s to 25s.

6. The method of producing a continuously cast slab for a low compression ratio Q345R super thick vessel steel according to claim 1, characterized in that, The inlet current intensity of the two-cool electric stirring is 500A to 650A, and the outlet current intensity is 500A to 650A.

7. The method of producing a continuously cast slab for a low compression ratio Q345R super thick vessel steel according to claim 1, characterized in that, The frequency of the two-cool electric stirring is 4Hz to 6Hz.