Production method of extra-thick Q460GJDZ35 steel plate with compression ratio smaller than or equal to 3

Abstract

The invention discloses a production method of an extra-thick Q460GJDZ35 steel plate with the compression ratio smaller than or equal to 3, and relates to the technical field of 111. According to the production method of the extra-thick Q460GJDZ35 steel plate with the compression ratio smaller than or equal to 3, steel comprises, by weight, 0.07%-0.08% of C, 0.25%-0.35% of Si, 1.60%-1.70% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.003% of S, 0.02%-0.05% of Al, 0.008%-0.02% of Ti, 0.06%-0.10% of Mo, 0.040%-0.050% of Nb, 0.30%-0.35% of Cr and the balance Fe and inevitable impurity elements. A 300mm continuous casting section is used for rolling, the thickness of the steel plate is 100-120mm (the compression ratio is less than or equal to 3), and the method comprises the key process steps of smelting, heating, differential temperature control of a plate blank and an intermediate blank, controlled rolling and controlled cooling, and pile cooling of the rolled plate. Through component and process optimization, the extra-thick Q460GJDZ35 steel plate with the structure in the full thickness direction mainly comprising bainite and ferrite of different degrees is produced, the yield strength of the steel plate is larger than or equal to 450 MPa, the tensile strength is larger than or equal to 570 MPa, the ductility is larger than or equal to 20%, the yield ratio is smaller than 0.83, the-20 DEG C impact energy is larger than or equal to 120 J, the ZL is larger than or equal to 45%, and the flaw detection standard reaches the first grade of the national standard.

Description

Technical Field

[0001] The invention relates to the technical field of wide and thick plate metallurgy, and in particular to a production method of an extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3. Background Art

[0002] With the further transformation of the economy to high quality and the deepening of urbanization, large public buildings are developing towards high-rise and long-span directions, and the use of high-rise building structural steel is becoming more and more extensive. High-rise building structural steel with thick walls, high strength, good toughness, low yield strength ratio, and excellent resistance to lamellar tearing can significantly improve the safety of the structure and reduce the damage to components caused by the impact of factors such as earthquakes. In order to meet the requirements of strength, yield strength ratio, toughness and high ZL for thicknesses above 100mm, the existing technology usually adopts heat treatment processes such as quenching and tempering or normalizing, which have long process flows and high process costs, such as Chinese patents CN101613828A, CN115341139A, CN101323929, etc. Chinese patent CN110616377A proposes a Q460GJ production steel plate with low yield ratio and high toughness, but the applicable thickness of the steel plate is ≤80mm, and the process will have a low strength at the 1 / 4 position when producing a thickness of more than 100mm, which cannot meet the Q460GJ steel grade requirements, and there is also an unstable situation of thick drawing Z35. Chinese patent CN114480969A proposes a production method for Q460GJ, a super thick steel with high toughness and high Z-direction performance and a compression ratio of ≤4, which is applicable to a production thickness of 80-100mm. Its chemical composition: C: 0.1-0.13, Si: 0.1-0.3, Mn: 1.1-1.3, P≤0.012, S≤0.003, Cr: 0.3-0.5, Ti: 0.01-0.02, Nb: 0.01-0.02, Ni: 0.1-0.3, V: 0.06-0.07, Als: 0.025-0.035, etc. and the post-rolling cooling temperature is 530-550℃. This composition and process are not suitable for expanding the production of thickness above 100mm. Because with the increase of thickness, the cooling rate must be further increased to improve the strength in the plate, and its carbon content is 0.1-0.13. Under the condition of further increasing the cooling rate, the further increase in the proportion of surface hard phase lath bainite, martensite and other organizations will further deteriorate the surface toughness and cause the yield strength ratio to rise, resulting in a large difference in performance in the full thickness direction, which cannot meet the steel grade requirements. Chinese patent CN105525209B proposes a low yield ratio Q460GJ construction steel and a production method thereof. The method is suitable for production of limited thickness (the upper limit thickness is 50mm in the example), using a C content of 0.17-0.19% and a final cooling temperature of 660-680°C. It is impossible to produce Q460GJD above 100mm.

[0003] For Q460GJDZ35 steel with thickness specifications of 100-120mm and above, there are few cases of large-scale and stable delivery using the TMCP process in China. At the same time, for extra-thick plates with a thickness greater than 100mm, the TMCP process must take into account the uniformity of strengthening, strength and yield strength ratio matching, strength and toughness matching, and ZL performance stabilization in the thickness direction, which is quite technically difficult and difficult to achieve with ordinary processes. In particular, due to the limitation of the compression ratio, it is often necessary to roll the ingot with a section greater than 300mm (usually using mold casting ingots), which has high production costs, unstable pass rates, and long process flows. However, the ultra-high-rise building steel industry continues to develop towards greater thicknesses, and has now expanded to more than 140mm. The downstream of the industrial chain is also paying more and more attention to the delivery cycle, and there is an urgent need for a production technology that can be achieved by using a common continuous casting ingot section and a TMCP rolling process at a relatively small compression ratio (compression ratio ≤3). Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a production method for extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3, which can solve the problems of long process flow and high process cost.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for producing a super thick Q460GJDZ35 steel plate with a compression ratio of ≤3, wherein the weight percentage of the steel is C=0.07%, Si=0.2%, Mn=1.55%, P=0.014%, S=0.0028%, Al=0.034%, Ti=0.012%, Nb=0.042%, Cr=0.28%, Mo=0.09%, and the balance is Fe and unavoidable impurity elements; the thickness of the steel plate is 120 mm, and the key process steps include:

[0006] S1 smelting: the molten steel is refined by LF, vacuum treated by VD, and then protected and cast into 300mm thick continuous casting billet;

[0007] S2 heating: During the heating process, the maximum furnace temperature is 1200°C, the soaking temperature is 1180°C, and the soaking time is 80 minutes;

[0008] S3 controlled rolling and controlled cooling: two-stage controlled rolling is adopted. The maximum pass reduction rate in the rough rolling process with a rolling temperature ≥ 1140°C is 19.7% (reduction amount 37mm), and this pass is also the last pass. The rough rolling final rolling temperature is 1170°C, the surface temperature of the finishing rolling is 817°C, the final rolling temperature is 828°C, and the maximum pass reduction rate of the finishing rolling is 6.2%; then it is rapidly cooled to 410-440°C at a cooling rate of about 6.6°C / s, and then put on the cooling bed;

[0009] S4 post-rolling pile cooling: air cooling on the cooling bed to 300-350 degrees and then into the insulation pit for pile cooling.

[0010] Preferably, the ingot has a low magnification of national standard C class 1.5.

[0011] Preferably, during the S2 heating, the core temperature of the slab at steel tapping is 1176°C.

[0012] Preferably, in the S3 controlled rolling and controlled cooling, the intermediate billet is 160 mm, and the upper and lower surfaces of the intermediate billet are water-cooled for 100 seconds.

[0013] Preferably, the stack cooling time is 64 hours, and the surface temperature is 69°C for destacking.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The production method of the extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3 adopts a low-carbon component design and a controlled rolling and controlled cooling (TMCP) process. It does not require complex heat treatment processes such as quenching and tempering / normalizing / tempering, which can greatly simplify the production process path, reduce costs and shorten delivery cycles.

[0016] 2. The production method of the extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3. When the compression ratio is ≥2.5, the 300mm section continuous casting billet that mainstream steel mills have can replace the large-section casting billet / mold casting ingot to roll the maximum thickness of 120mm extra-thick plate, thereby avoiding additional equipment investment, achieving cost reduction, efficiency improvement, and quality improvement, and is more in line with the future development direction of steel under the "dual carbon strategy".

[0017] 3. The production method of the extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3. The controlled rolling and controlled cooling (TMCP) process adopted by the present invention has a relatively complicated control process, but can be achieved using existing production line equipment. It can stably produce extra-thick Q460GJDZ35 steel plates with a maximum thickness of 120 mm, and the yield strength of the steel plates is ≥450MPa, the tensile strength is ≥570MPa, the yield strength ratio is <0.83, the -20℃ impact energy is ≥120J, and the ZL is ≥45%, which fully meets the national standard requirements.

[0018] 4. The production method of the ultra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3. The thick plate produced by the present invention has excellent strength and toughness and anti-laminar tearing performance in the full thickness direction. The production method can be expanded to use 350mm cross-section continuous casting billets to roll and produce 120-140mm thick TMCP type Q460GJD steel, and can also serve as a reference for the production of other Q500-Q550 level low yield ratio, high Z-direction performance ultra-thick plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0020] Figure 1 This is a schematic diagram of the metallographic structure of the steel plate at 1 / 4 thickness of Example 1 of the present invention; DETAILED DESCRIPTION

[0021] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0022] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0023] In the description of the present invention, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0024] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0025] See also Figure 1

[0026] The present invention provides a technical solution: Embodiment 1

[0027] A method for producing extra-thick Q460GJDZ35 steel with a compression ratio of ≤3, wherein the weight percentage of the steel is C=0.07%, Si=0.2%, Mn=1.55%, P=0.014%, S=0.0028%, Al=0.034%, Ti=0.012%, Nb=0.042%, Cr=0.28%, Mo=0.09%, and the balance is Fe and unavoidable impurity elements; the thickness of the steel plate is 120 mm, and the key process steps include:

[0028] S1 smelting: the molten steel is refined by LF, vacuum treated by VD, and then protected and cast into 300mm thick continuous casting billet, the low multiple of the billet is national standard C class 1.5;

[0029] S2 heating: During the heating process, the highest furnace temperature is 1200℃, the soaking temperature is 1180℃, the soaking time is 80min, and the slab core temperature is 1176℃;

[0030] S3 controlled rolling and controlled cooling: two-stage controlled rolling is adopted. The maximum pass reduction rate in the rough rolling process with a rolling temperature ≥1140℃ is 19.7% (reduction amount 37mm), and this pass is also the last pass. The rough rolling final rolling temperature is 1170℃; the intermediate billet is 160mm, and the upper and lower surfaces of the intermediate billet are water-cooled for 100s. The surface temperature of the finishing rolling is 817℃, the final rolling temperature is 828℃, and the maximum pass reduction rate of the finishing rolling is 6.2%; then it is rapidly cooled to 410-440℃ at a cooling rate of about 6.6℃ / s, and placed on a cooling bed after cooling;

[0031] S4 post-rolling stack cooling: air cooling on the cooling bed to 300-350 degrees, then stack cooling in the insulation pit, stack cooling time 64 hours, surface temperature 69 degrees Celsius, stack removal;

[0032] Figure 1 This is the metallographic structure at 1 / 4 thickness of the steel plate of Example 1 of the present invention. It can be seen that the microstructure is mainly composed of refined bainite laths and acicular ferrite, and the grain size is level 9. The sample at 1 / 4 thickness of the steel plate of Example 1 was taken for tensile and Charpy V-type impact tests and full-thickness ZL tests: the yield strength is 499 MPa, the tensile strength is 644 MPa, the elongation is 21.5%, the yield strength ratio is 0.77, the -20°C impact energy is 172 / 260 / 184 J, and the ZL is 56% / 53% / 63%.

[0033] Example 2

[0034] A method for producing extra-thick Q460GJDZ35 steel with a compression ratio of ≤3, wherein the weight percentage of the steel is C=0.07%, Si=0.18%, Mn=1.51%, P=0.013%, S=0.0016%, Al=0.032%, Ti=0.012%, Nb=0.040%, Cr=0.26%, Mo=0.08%, and the balance is Fe and unavoidable impurity elements; the thickness of the steel plate is 110 mm, and the key process steps include:

[0035] S1 smelting: the molten steel is refined by LF, vacuum treated by RH, and then protected and cast into 300mm thick continuous casting billet, the billet low multiple national standard C class 1.0;

[0036] S2 heating: During the heating process, the highest furnace temperature is 1200℃, the soaking temperature is 1180℃, the soaking time is 67min, and the slab core temperature is 1175℃;

[0037] S3 controlled rolling and controlled cooling: two-stage controlled rolling is adopted. The maximum pass reduction rate in the rough rolling process with a rolling temperature ≥1140℃ is 18.5% (reduction amount 34mm), and this pass is also the last pass. The rough rolling final rolling temperature is 1180℃; the intermediate billet is 150mm, and the upper and lower surfaces of the intermediate billet are water-cooled for 100s. The surface temperature of the finishing rolling is 819℃, the final rolling temperature is 816℃, and the maximum pass reduction rate of the finishing rolling is 5.3%; then it is rapidly cooled to 420-450℃ at a cooling rate of about 6.1℃ / s, and placed on a cooling bed after cooling;

[0038] S4 post-rolling stack cooling: air cooling on the cooling bed to 300-350℃, then put into the insulation pit for stack cooling, the stack cooling time is 74 hours, and the surface temperature is 53℃ for stacking;

[0039] The sample at 1 / 4 thickness of the steel plate in Example 2 was taken for tensile and Charpy V-type impact test, and full-thickness ZL test: the yield strength was 495 MPa, the tensile strength was 640 MPa, the elongation was 22.5%, the yield strength ratio was 0.77, the impact energy at -20°C was 165 / 200 / 180 J, and the ZL was 59% / 54% / 65%.

[0040] Example 3

[0041] A method for producing extra-thick Q460GJDZ35 steel with a compression ratio of ≤3, wherein the weight percentage of the steel is C=0.07%, Si=0.29%, Mn=1.64%, P=0.013%, S=0.0015%, Al=0.03%, Ti=0.012%, Nb=0.042%, Cr=0.31%, Mo=0.08%, and the balance is Fe and unavoidable impurity elements; the thickness of the steel plate is 100 mm, and the key process steps include:

[0042] S1 smelting: the molten steel is refined by LF, vacuum treated by RH, and then protected and cast into 300mm thick continuous casting billet, the billet low multiple national standard C class 1.5;

[0043] S2 heating: During the heating process, the highest furnace temperature is 1200℃, the soaking temperature is 1180℃, the soaking time is 65min, and the slab core temperature is 1168℃;

[0044] S3 controlled rolling and controlled cooling: two-stage controlled rolling is adopted. The maximum pass reduction rate in the rough rolling process with a rolling temperature ≥1140℃ is 22.2% (reduction amount 40mm), and this pass is also the last pass. The rough rolling final rolling temperature is 1152℃; the intermediate billet is 140mm, and the upper and lower surfaces of the intermediate billet are water-cooled for 90s. The surface temperature of the finishing rolling is 825℃, the final rolling temperature is 811℃, and the maximum pass reduction rate of the finishing rolling is 8.57%; then it is rapidly cooled to 420-450℃ at a cooling rate of about 6.1℃ / s, and then put on the cooling bed;

[0045] S4 post-rolling stack cooling: air cooling on the cooling bed to 300-350℃, then put into the insulation pit for stack cooling, the stack cooling time is 63 hours, and the surface temperature is 47℃ for stacking;

[0046] The sample at 1 / 4 thickness of the steel plate in Example 3 was taken for tensile and Charpy V-type impact test, and full-thickness ZL test: the yield strength was 486 MPa, the tensile strength was 620 MPa, the elongation was 24%, the yield strength ratio was 0.78, the impact energy at -20°C was 273 / 242 / 226 J, and the ZL was 67% / 58% / 63%.

[0047] Furthermore, the present invention adopts 300mm continuous casting billet cross-section rolling, and the thickness of the finished steel plate can reach 100-120mm (compression ratio ≤3). The composition is designed with low C, low P, low S, and added Nb and a small amount of Mo. Through slab temperature-limited heating + rough rolling and large reduction + intermediate billet water cooling (differential temperature control) + controlled rolling and controlled cooling + post-rolling stack cooling, without any post-rolling heat treatment, the continuous casting billet can be used to produce 100-120mm ultra-thick Q460GJDZ35 steel plates with excellent performance under the condition of compression ratio ≤3. The microstructure of the steel plate in the full thickness direction is mainly bainite + ferrite to varying degrees, the yield strength is ≥450MPa, the tensile strength is ≥570MPa, the elongation is ≥20%, the yield strength ratio is <0.83, the -20℃ impact energy is ≥120J, and the ZL is ≥45%. The flaw detection standard reaches the national standard level 1.

[0048] Furthermore, the low C in the composition design adopted by the present invention is to improve the toughness of the steel, and the organizational design of low-carbon bainite + ferrite can also ensure sufficient cooling time for the thick plate in a wider cooling rate range, achieve sufficient cooling in the thickness direction, and avoid the deterioration of toughness and elongation caused by martensiticization of the surface hard phase organization of medium and high carbon components; smelting and slag removal, controlling the S content in the steel to be less than 0.003%, can effectively reduce the formation of brittle inclusions such as MnS in the core of the steel plate, and improve the flaw detection quality and lamellar fracture resistance of the core of the thick plate; adding Cr is to improve the strength of the steel and improve the segregation of manganese; adding micro-alloying elements such as Nb and Ti plays an important role in refining the austenite grain size during heating and rolling. At the same time, the precise control of the Ti content (about 0.012%) effectively utilizes the strong affinity between Ti and S to control the morphology and distribution of (MnTi)S and Ti4Ca2S2. Improve the lamellar fracture toughness of extra-thick steel plates. The Mo element has a significant solid solution strengthening effect. At the same time, the Mo element can suppress the decomposition of austenite while reducing the austenite phase area, reduce the phase transition temperature, and increase the hardenability of the steel plate. It can improve the strength of the full thickness of the steel plate and reduce the strength difference between the core and the surface of the extra-thick plate. The addition of no more than 0.1% Mo content can control the Pcm value of the steel plate within 0.19 and give full play to the beneficial effect of the Mo element. It should be noted that the addition of excessive Mo will sharply deteriorate the toughness and welding performance of the steel plate, and will significantly increase the alloy cost. The low magnification requirement is within 1.5 for Class C because it is difficult for the TMCP process to close the severe shrinkage cavities and segregation in the core area of ​​large ingots due to the compression ratio. The original low magnification quality of the ingot must be improved through fine control of continuous casting to ensure that the final finished steel plate ZL achieves a high lamellar tear resistance of more than 45%;

[0049] Furthermore, the main purpose of the furnace temperature limit ≤1200℃ heating adopted in the present invention is to control the original austenite grain size, and the long-term soaking is to ensure the alloy solid solution effect, so as to provide conditions for the subsequent TMCP process to control the number and morphology of bainite transformation and obtain fine bainite. The present invention fully utilizes the high-load characteristics of the rolling line equipment, and the rough rolling adopts the "high temperature and large reduction" mode, requiring a large pass reduction in the rough rolling stage (at least one pass ≥18%; the final rough rolling pass ≥16%), in order to improve the austenite refinement effect of recrystallization zone rolling under limited compression ratio conditions, and improve the core deformation amount at the same time. The present invention adopts differential temperature rolling measures, including descaling in each pass in the rough rolling stage, cooling the surface of the intermediate billet by intermediate water cooling, and low rolling temperature before the surface of the finishing rolling is fully returned to red, etc., because the differential Warm rolling can introduce greater plastic deformation and stress in the core of the steel plate, which can effectively promote the closure of point defects such as pores, cracks, and looseness. At the same time, it can also weaken the organizational stratification caused by the segregation of the ingot and the ingot through sufficient recrystallization, thereby significantly improving the ultra-thick anti-laminar tearing ability (Z-direction performance) and the qualified rate of steel plate flaw detection. For steel plates with a thickness of 100-120mm and above, the traditional temperature equalization process can only produce grade 3 steel plates, while differential temperature rolling can produce grade 2 and grade 1 flaw detection steel plates, and the ZL performance achieves an average of more than 45%, with obvious effects. The cumulative reduction in the finishing rolling (non-recrystallization zone) stage is greater than 40mm, and the low-temperature rolling is to increase the density of defects such as dislocations, substructures and deformation bands, and provide sufficient forming positions for ferrite during cooling after rolling, so as to better achieve grain refinement and improve strength and toughness.

[0050] Furthermore, the rolling cooling system adopted in the present invention requires the water temperature of the cold water to be 770-810°C, the final cooling to be 400-450°C and the cooling rate to be ≥5°C / s (cooling time 50-60s). In order to ensure that the steel plate undergoes transformation in the bainite interval and realizes the structure dominated by bainite + ferrite in the full thickness direction, and at the same time, due to the large thickness of the steel plate, there is a relatively slow gradient process for the surface cooling of the steel plate and the heat exchange in the core, and sufficient cooling time needs to be ensured. The MULPIC cooling system has a high pressure (10-15s) and low pressure (40-45s) intervals with a total cooling time of 50-60S, which can ensure sufficient red heat exchange in the thickness direction, improve the cooling rate and hardenability of the core, and realize that there is still sufficient bainite hard phase structure from the 1 / 4 position to the 3 / 8 position of the thickness, supporting the strength of Q460 level;

[0051] Furthermore, the post-rolling stack cooling system of the present invention requires that the steel plate entry temperature be 300-350°C, the stack cooling time be ≥60H and the surface temperature of the steel plate after stack cooling be <90°C, in order to ensure the slow cooling hydrogen evolution effect, so that the hydrogen in the steel can be fully overflowed, and hydrogen-induced cracks in the steel can be avoided, resulting in ZL deterioration and even failure of steel plate flaw detection.

[0052] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present invention.

Claims

1. A method for producing a super thick Q460GJDZ35 steel plate with a compression ratio of ≤3, characterized in that: The weight percentage of the steel is C=0.07%, Si=0.2%, Mn=1.55%, P=0.014%, S=0.0028%, Al=0.034%, Ti=0.012%, Nb=0.042%, Cr=0.28%, Mo=0.09%, and the balance is Fe and unavoidable impurity elements; The thickness of the steel plate is 120 mm, and the key process steps include: S1 smelting: the molten steel is refined by LF, vacuum treated by VD, and then protected and cast into 300mm thick continuous casting billet; S2 heating: During the heating process, the maximum furnace temperature is 1200°C, the soaking temperature is 1180°C, and the soaking time is 80 minutes; S3 controlled rolling and controlled cooling: two-stage controlled rolling is adopted. The maximum pass reduction rate in the rough rolling process with a rolling temperature ≥ 1140°C is 19.7% (reduction amount 37mm), and this pass is also the last pass. The rough rolling final rolling temperature is 1170°C, the surface temperature of the finishing rolling is 817°C, the final rolling temperature is 828°C, and the maximum pass reduction rate of the finishing rolling is 6.2%; then it is rapidly cooled to 410-440°C at a cooling rate of about 6.6°C / s, and then put on the cooling bed; S4 post-rolling pile cooling: air cooling on the cooling bed to 300-350 degrees and then put into the insulation pit for pile cooling.

2. The method for producing a super thick Q460GJDZ35 steel plate with a compression ratio of ≤3 according to claim 1, characterized in that: The low magnification of the ingot is 1.5 according to the national standard C category.

3. The method for producing a super thick Q460GJDZ35 steel plate with a compression ratio of ≤3 according to claim 1, characterized in that: During the S2 heating, the core temperature of the slab is 1176°C.

4. The method for producing a super thick Q460GJDZ35 steel plate with a compression ratio of ≤3 according to claim 1, characterized in that: The S3 controlled rolling and controlled cooling, the intermediate billet is 160mm, and the upper and lower surfaces of the intermediate billet are water-cooled for 100s.

5. The method for producing a super thick Q460GJDZ35 steel plate with a compression ratio of ≤3 according to claim 1, characterized in that: The stack cooling time is 64 hours, and the surface temperature is 69°C when the stack is removed.

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