A production method for extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3

Abstract

The invention discloses a production method of an extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3, and relates to the technical field of 111. The invention discloses a production method for an extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3. The steel comprises the following weight percentages: C = 0.07% to 0.08%, Si = 0.25% to 0.35%, Mn = 1.60% to 1.70%, P ≤ 0.015%, S ≤ 0.003%, Al = 0.02% to 0.05%, Ti = 0.008% to 0.02%, Mo = 0.06% to 0.10%, Nb = 0.040% to 0.050%, Cr = 0.30% to 0.35%, and the remainder is Fe and unavoidable impurity elements. The steel plate is rolled using a 300mm continuous casting section, and has a thickness of 100 to 120mm (compression ratio ≤ 3). The key process steps include smelting, heating, temperature difference control between slab and intermediate slab, controlled rolling and controlled cooling, and pile cooling of the plate after rolling. By optimizing the composition and process, the present invention produces an extra-thick Q460GJDZ35 steel plate with a full-thickness microstructure dominated by bainite + ferrite to varying degrees. The plate has a yield strength ≥450MPa, a tensile strength ≥570MPa, an elongation ≥20%, a yield strength ratio <0.83, an impact energy at -20°C ≥120J, and a ZL ≥45%. The flaw detection standard meets the national standard level 1.

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 economic transformation toward high quality and the deepening of urbanization, large public buildings are developing in the direction of high-rise and long-span structures, and the use of steel for high-rise building structures is becoming increasingly widespread. 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 structural safety and reduce damage to components caused by impacts such as earthquakes. To meet the strength, yield strength ratio, toughness, and high ZL requirements for thicknesses over 100 mm, existing technologies typically use heat treatment processes such as tempering or normalizing, which are lengthy and costly. Examples include Chinese patents CN101613828A, CN115341139A, and CN101323929. Chinese patent CN110616377A proposes a method for producing Q460GJ steel plates with a low yield ratio and high toughness. However, this method is suitable for thicknesses ≤80mm. Furthermore, when producing plates with a thickness of 100mm or more, the strength at the quarter-meter position is too low to meet Q460GJ grade requirements. Furthermore, Z35 steel is unstable when thickly drawn. Chinese patent CN114480969A proposes a method for producing Q460GJ steel with a compression ratio ≤4, high toughness, and high Z-direction properties, suitable for thicknesses of 80-100mm. Its chemical composition is: 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, and the post-rolling cooling temperature is 530-550°C. This composition and process are not suitable for expanded production of thicknesses above 100mm. This is because as the thickness increases, the cooling rate must be further increased to improve the plate's strength. The carbon content is 0.1-0.13. If the cooling rate is further increased, the proportion of surface hard phases such as lath bainite and martensite will further increase, further deteriorating the surface toughness and causing an increase in the yield strength ratio. This will result in a large difference in properties along the through-thickness direction and fail to meet the steel grade requirements. Chinese patent CN105525209B proposes a low-yield ratio Q460GJ construction steel and its production method. This method is suitable for production of limited thickness (the upper limit thickness is 50mm in an example), uses a C content of 0.17-0.19% and a final cooling temperature of 660-680℃, and cannot produce Q460GJD above 100mm.

[0003] For Q460GJDZ35 steel in thicknesses of 100-120mm and above, the TMCP process is currently rarely used in China for large, stable deliveries. Furthermore, for extra-thick plate exceeding 100mm, the TMCP process must balance uniformity of reinforcement through the thickness, strength-to-yield ratio matching, strength-toughness matching, and ZL performance stabilization, presenting considerable technical challenges and making it difficult to achieve using conventional processes. In particular, due to compression ratio limitations, rolling of ingots with sections greater than 300mm is often required (typically using die-cast ingots), resulting in high production costs, inconsistent yield rates, and lengthy process flows. However, the ultra-high-rise steel industry continues to expand to even thicker thicknesses, currently exceeding 140mm. With increasing concern about lead times downstream in the supply chain, a production technology that can achieve this at a lower compression ratio (≤3) using conventional continuously cast ingot sections and TMCP rolling is urgently needed. 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 plates 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 an extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3, wherein the weight percentage composition 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 steel plate has a thickness of 120 mm, and the key process steps include:

[0006] S1 smelting: The molten steel is refined by LF, vacuum treated by VD, and then cast into 300mm thick continuous casting billets under protection;

[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: adopts two-stage controlled rolling. The maximum pass reduction rate in the rough rolling process with a rolling temperature of ≥1140℃ is 19.7%. This pass is also the last pass. The rough rolling finish temperature is 1170℃, the finishing rolling surface temperature is 817℃, and the finishing temperature is 828℃. The maximum pass reduction rate in the finishing rolling is 6.2%. Then it is rapidly cooled to 410~440℃ at a cooling rate of 6.6℃ / s and placed on a cooling bed after cooling.

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

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

[0011] Preferably, during the S2 heating, the core temperature of the slab during 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 before destacking.

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

[0015] The production method of the ultra-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] The production method of the extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3, under the condition of a compression ratio of ≥2.5, can realize the replacement of large-section cast billets / mold-cast ingots with 300mm cross-section continuous casting billets, which are available in mainstream steel mills, to roll extra-thick plates with a maximum thickness of 120mm, thereby avoiding additional equipment investment, achieving cost reduction, efficiency improvement, and quality improvement, and being more in line with the future development direction of steel under the "dual carbon strategy".

[0017] The method for producing extra-thick Q460GJDZ35 steel plates with a compression ratio of ≤3 adopts a controlled rolling and controlled cooling (TMCP) process. Although the control process is relatively complex, it can be implemented using existing production line equipment. Extra-thick Q460GJDZ35 steel plates with a maximum thickness of 120 mm can be stably produced. The yield strength of the steel plates is ≥450 MPa, the tensile strength is ≥570 MPa, the yield strength ratio is <0.83, the impact energy at -20°C is ≥120 J, and the ZL is ≥45%, which fully meets the requirements of national standards.

[0018] The invention discloses a method for producing an extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3. The thick plate produced by the invention has excellent strength and toughness and resistance to lamellar tearing 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 grade extra-thick plates with low yield ratio and high Z-direction performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0020] Figure 1Schematic diagram of the metallographic structure of the steel plate at 1 / 4 thickness according to 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 should not 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., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They 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. Therefore, they cannot be understood as limitations on the present invention.

[0023] In the description of this invention, terms such as "greater than," "less than," and "exceed" are understood to exclude the number itself, while terms such as "above," "below," and "within" are understood to include the number itself. The use of terms such as "first" and "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0024] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting 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 based on the specific content of the technical solution.

[0025] See also Figure 1

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

[0027] A method for producing extra-thick Q460GJDZ35 steel with a compression ratio of ≤3, wherein the steel comprises, by weight, 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 remainder is Fe and unavoidable impurity elements; the steel plate has a thickness of 120 mm, and the key process steps include:

[0028] S1 smelting: The molten steel is refined by LF and vacuum treated by VD, and then cast into 300mm thick continuous casting billets under protection. The billet low magnification is 1.5 of national standard C class;

[0029] S2 heating: During the heating process, the maximum furnace temperature is 1200°C, the soaking temperature is 1180°C, the soaking time is 80 minutes, and the slab core temperature at tapping is 1176°C.

[0030] S3 controlled rolling and controlled cooling: adopts two-stage controlled rolling. The maximum pass reduction rate in the rough rolling process with a rolling temperature of ≥1140℃ is 19.7%. This pass is also the last pass. The rough rolling final rolling temperature is 1170℃. The intermediate billet is 160mm. The upper and lower surfaces of the intermediate billet are water-cooled for 100s. The surface temperature of the finishing rolling is 817℃ at the start and 828℃ at the finish rolling. 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 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 put into the insulation pit for stack cooling. The stack cooling time is 64 hours, and the surface temperature is 69 degrees Celsius for destacking.

[0032] Figure 1 The metallographic structure at 1 / 4 thickness of the steel plate of Example 1 of the present invention shows that the microstructure is mainly composed of refined bainite laths and acicular ferrite, and the grain size is level 9; a sample at 1 / 4 thickness of the steel plate of Example 1 is taken for tensile and Charpy V-type impact tests, and full-thickness ZL test: 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 impact energy at -20°C is 172 / 260 / 184 J, and the ZL is 56% / 53% / 63%.

[0033] Example: A method for producing extra-thick Q460GJDZ35 steel with a compression ratio of ≤3, wherein the steel has a weight percentage composition of 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 steel plate has a thickness of 110 mm, and the key process steps include:

[0034] S1 smelting: The molten steel is refined by LF and vacuum treated by RH, and then cast into 300mm thick continuous casting billets under protection. The billets are of low magnification national standard C class 1.0;

[0035] S2 heating: During the heating process, the maximum furnace temperature is 1200°C, the soaking temperature is 1180°C, the soaking time is 67 minutes, and the slab core temperature at tapping is 1175°C.

[0036] S3 controlled rolling and controlled cooling: adopts two-stage controlled rolling. The maximum pass reduction rate in the rough rolling process with a rolling temperature of ≥1140℃ is 18.5% (reduction amount 34mm). This pass is also the last pass. The rough rolling final rolling temperature is 1180℃. The intermediate billet is 150mm. The upper and lower surfaces of the intermediate billet are water-cooled for 100s. The surface temperature of the finishing rolling is 819℃ at the start and 816℃ at the finish rolling. 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 6.1℃ / s. After cooling, it is placed on a cooling bed.

[0037] 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 destacking.

[0038] A sample at 1 / 4 thickness of the steel plate of Example 2 was taken for tensile and Charpy V-type impact tests, and a 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%.

[0039] Example: A method for producing extra-thick Q460GJDZ35 steel with a compression ratio of ≤3, wherein the weight percentage composition 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 steel plate has a thickness of 100 mm, and the key process steps include:

[0040] S1 smelting: The molten steel is refined by LF and vacuum treated by RH, and then cast into 300mm thick continuous casting billets under protection. The billet low magnification is 1.5 of national standard C class;

[0041] S2 heating: During the heating process, the maximum furnace temperature is 1200°C, the soaking temperature is 1180°C, the soaking time is 65 minutes, and the slab tapping core temperature is 1168°C.

[0042] S3 controlled rolling and controlled cooling: adopts two-stage controlled rolling. The maximum pass reduction rate in the rough rolling process with a rolling temperature of ≥1140℃ is 22.2% (reduction amount 40mm). This pass is also the last pass. The rough rolling final rolling temperature is 1152℃. The intermediate billet is 140mm. The upper and lower surfaces of the intermediate billet are water-cooled for 90s. The surface temperature of the finishing rolling is 825℃ at the start and 811℃ at the finish rolling temperature. 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 6.1℃ / s and placed on a cooling bed after cooling.

[0043] 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 destacking.

[0044] A sample at 1 / 4 thickness of the steel plate of Example 3 was taken for tensile and Charpy V-type impact tests, and a 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%.

[0045] 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 at a compression ratio of ≤3. The structure of the steel plate in the full thickness direction is mainly bainite + ferrite to varying degrees, with yield strength ≥450MPa, tensile strength ≥570MPa, elongation ≥20%, yield strength ratio <0.83, -20℃ impact energy ≥120J, ZL ≥45%, and the flaw detection standard meets the national standard level 1.

[0046] Furthermore, the low C content in the composition design adopted in the present invention is to improve the toughness of the steel, and the low-carbon bainite + ferrite structure design 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 martensite formation of the surface hard phase structure of medium and high carbon components; S is removed during slag smelting and the S content in the steel is controlled to be less than 0.003%, which can effectively reduce the formation of brittle inclusions such as MnS in the core of the steel plate, improve the flaw detection quality and lamellar fracture resistance of the core of the thick plate; Cr is added to improve the strength of the steel and improve the segregation of manganese; the addition of microalloying 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 (MnTi) The morphology and distribution of S and Ti4Ca2S2 improve the lamellar fracture toughness of ultra-thick steel plates. The solid solution strengthening effect of Mo element is significant. At the same time, Mo element inhibits the decomposition of austenite while reducing the austenite phase area, reduces the phase transformation temperature, and increases 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 surface of the ultra-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 effects of Mo element. It should be noted that excessive Mo addition 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 C category 1.5 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 limitation. The original low magnification quality of the ingot must be improved through refined control of continuous casting to ensure that the final finished steel plate ZL achieves a high lamellar tearing resistance of more than 45%;

[0047] 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 longer time of equalization is to ensure the alloy solid solution effect, to provide conditions for the subsequent TMCP process to control the number and morphology of bainite transformation, and to 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 at the same time improve the core deformation amount. The present invention adopts differential temperature rolling measures, including descaling in each pass in the rough rolling stage, cooling the intermediate billet surface by intermediate water cooling, and low starting rolling temperature before the finishing surface 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, effectively promoting the closure of point defects such as pores, cracks, and porosity. At the same time, it can also weaken the structural stratification caused by segregation of the ingot and slab through sufficient recrystallization, thereby significantly improving the ultra-thick lamellar tearing resistance (Z-direction performance) and the steel plate flaw detection pass rate. For steel plates with a thickness of 100-120mm and above, the traditional uniform temperature 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 value of more than 45%, which is a significant effect. The cumulative reduction in the finishing rolling (non-recrystallization zone) is greater than 40mm, and the rolling is started at a low temperature. This 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, thereby better achieving grain refinement and improving strength and toughness.

[0048] Furthermore, the rolling cooling system adopted by the present invention requires a cold water entry temperature of 770-810°C, a final cooling of 400-450°C, and a cooling rate of ≥5°C / s (cooling time 50-60s). In order to ensure that the steel plate undergoes transformation in the bainite range and realizes a 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 between the surface cooling and the core heat exchange of the steel plate, which requires sufficient cooling time. The MULPIC cooling system uses a high-pressure (10-15s) and low-pressure (40-45s) cooling time of 50-60s in two sections to ensure sufficient red-hot heat exchange in the thickness direction, improve the cooling rate and hardenability of the core, and achieve sufficient bainite hard phase structure from 1 / 4 to 3 / 8 of the thickness, supporting the strength of Q460 level.

[0049] 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 ≥60 hours, and the surface temperature of the steel plate after stack cooling be <90°C. This is to ensure the slow cooling hydrogen evolution effect, so that hydrogen in the steel can be fully overflowed, thereby avoiding hydrogen-induced cracks in the steel, resulting in ZL deterioration and even failure of steel plate flaw detection.

[0050] 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 scope of knowledge possessed by ordinary technicians in the technical field without departing from the spirit of the present invention.

Claims

1. A method for producing extra-thick Q460GJDZ35 steel plate with a compression ratio of ≤3, characterized by: The weight percentage composition of 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 cast into 300mm thick continuous casting billets under protection; 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: adopts two-stage controlled rolling. The maximum pass reduction rate in the rough rolling process with a rolling temperature of ≥1140℃ is 19.7%. This pass is also the last pass. The rough rolling finish temperature is 1170℃, the finishing rolling surface temperature is 817℃, and the finishing temperature is 828℃. The maximum pass reduction rate in the finishing rolling is 6.2%. Then it is rapidly cooled to 410~440℃ at a cooling rate of 6.6℃ / s and placed on a cooling bed after cooling. S4 post-rolling pile cooling: air cooling on the cooling bed to 300-350 degrees Celsius and then pile cooling in the insulation pit.

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 process has an intermediate billet of 160 mm and the upper and lower surfaces of the intermediate billet are cooled with water for 100 seconds.

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 before destacking.

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