A thermomechanical rolling method for improving the core performance of 80-100 mm super-thick high-strength and high-toughness anti-laminated tearing steel plate

Abstract

The application discloses a hot mechanical rolling method for improving the core performance of 80-100mm super-thick high-strength and high-toughness anti-laminated tearing steel plate, which lowers the surface temperature of the blank by rapidly water channeling of the blank in each rolling pass in the high-temperature recrystallization zone, promotes the increase of the surface rolling deformation resistance, and makes the deformation penetrate to the core; after repeated water channeling and large reduction rolling, more complete recrystallization occurs in the core; no water channeling between two rolling passes after rolling makes the surface complete recrystallization, and makes the austenite structure in the thickness direction uniform; and interval strong cooling and twice continuous medium cooling after rolling promote the uniform phase change of the super-thick steel plate, and excellent high-strength and high-toughness and anti-laminated tearing performance are obtained, and especially the core performance of the super-thick steel plate is remarkably improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of extra-thick high-toughness steel plate, and particularly relates to a thermomechanical rolling method for improving the core performance of 80-100mm extra-thick high-toughness and lamellar-tear-resistant steel plate. BACKGROUND

[0002] The steel structure of 80-100mm extra-thick high-toughness steel plate tends to be large and high-end, and the load and force transmission of the component are very complex. In order to meet the safety of use, many customers also put forward the requirement that the steel plate must ensure the core low-temperature toughness. However, due to the extra thickness of the steel plate, although the deformation austenite grains can be refined by large reduction in the recrystallization zone, the deformation is concentrated on the surface when the steel plate is rolled in the recrystallization zone, and the center temperature of the steel plate is high and difficult to deform, which will lead to coarse grains in the core and large difference in grain size between the core and the surface. The conventional two-stage rolling process of large reduction in the recrystallization zone and finish rolling in the unrecrystallization zone is difficult to meet the core performance requirements of the order.

[0003] Chinese patent CN104404214A discloses a manufacturing method of high-toughness and lamellar-tear-resistant steel plate with a thickness of 50-80mm, and specifically discloses that the continuous casting billet with the same composition of the steel plate is heated to 1210-1250℃, the heating time is controlled at 1.1-1.2min / mm, the billet discharge temperature is greater than or equal to 1150℃, the recrystallization zone rolling temperature is greater than or equal to 1050℃, 6-7 passes are rolled, the intermediate billet is kept warm, the unrecrystallization zone rolling temperature is controlled at 800-830℃, the finish rolling temperature is controlled at 800-830℃, 8-9 passes are rolled, and the steel plate is cooled after rolling at a cooling speed of 6.5-13℃ / S and 2.0-6.0℃ / S in the laminar cooling zone and the medium cooling zone respectively, and the roll speed of the ACC system is 0.6-0.8m / s, so that the grain size of the prepared steel plate is 10.5-12, and the comprehensive performance of the steel plate is that the yield strength is greater than or equal to 420MPa, the longitudinal impact energy at-40℃ is greater than or equal to 200J, and the Z-direction performance is that the reduction of area is greater than or equal to 65%. The patent mainly controls the cooling speed by reasonably opening the water groups of the strong cooling zone and the medium cooling zone, effectively refines the grains and the structure of the steel, and reduces the core defects. However, the method is only suitable for the high-toughness and lamellar-tear-resistant steel plate with a thickness of 50-80mm, and cannot effectively control the core defects of the extra-thick high-toughness and lamellar-tear-resistant steel plate with a thickness of more than 80mm. SUMMARY

[0004] To solve the above technical problems, the application provides a hot mechanical rolling method for improving the core performance of 80-100mm super-thick high-strength and high-toughness anti-laminated tearing steel plate.

[0005] The application also provides a 80-100mm super-thick high-strength and high-toughness anti-laminated tearing steel plate produced by the method, which has the following performances: yield strength ≥420MPa, tensile strength ≥520MPa, A ≥22.5%, longitudinal impact energy at-40℃ ≥140J, Z-direction performance ≥45%; core performance: yield strength ≥420MPa, tensile strength ≥520MPa, A ≥21%, longitudinal impact energy at-40℃ ≥130J, and the core has excellent low-temperature toughness.

[0006] To achieve the above object, the application adopts the following technical scheme:

[0007] A hot mechanical rolling method for improving the core performance of 80-100mm super-thick high-strength and high-toughness anti-laminated tearing steel plate, which comprises the following steps: controlling rolling after heating the casting blank, and then controlling cooling;

[0008] In the controlling rolling step, first, rolling in the recrystallization zone, the opening rolling temperature ≥1070℃, water cooling is performed after each rolling pass, but water cooling is not performed between the last two rolling passes, and the final rolling temperature ≥1000℃; then, rolling in the non-recrystallization zone, the opening rolling temperature ≤850℃, and the final rolling temperature 810℃±10℃;

[0009] In the controlling cooling step, in order to ensure that the steel plate is gradually cooled in the thickness direction and phase change occurs in this stage, first, the interval water group is opened to rapidly cool to 610-630℃ at a cooling speed of 13.5-15.5℃ / s, and then the medium cooling is performed at a cooling speed of 6.5-8.5℃ / s, and the reheat temperature is controlled at 580±10℃. If the cooling speed during rapid cooling is lower than 13.5-15.5℃ / s, the required temperature for phase change cannot be reached, which will cause disordered structure; if the cooling speed during medium cooling is lower than 6.5-8.5℃ / s, the grain will grow and the performance of the steel plate will be deteriorated.

[0010] When rolling in the recrystallization zone, the roll speed during water leakage is 1.2-1.5m / s, the ratio of the water flow rate to the water leakage rate is 1.5-1.8, and the water leakage rate is 100-120m 3 / h.

[0011] In the recrystallization zone, the reduction of each pass is greater than or equal to 12%; in the non-recrystallization zone, the cumulative deformation rate below 850℃ is greater than or equal to 33%.

[0012] In the heating step, a walking beam furnace is used for heating; the heating temperature of the continuous casting billet is 1220-1270℃, the heating time is controlled at 1.1-1.2min / mm, and the billet discharge temperature is greater than or equal to 1150℃.

[0013] In the controlled cooling step, the first to sixth groups of headers are provided in the strong cooling zone, the water flow of the middle chamber of the upper header is 260-270m 3 / h, and the water flow of the lower header is 1.5 times that of the upper header; the seventh to twenty-fourth groups of headers are provided in the medium cooling zone, the water flow of the middle chamber of the upper header is 120-140m 3 / h, and the water flow of the lower header is 2.5 times that of the upper header.

[0014] In the controlled cooling step, the second, fourth and sixth groups of headers in the strong cooling zone are opened, and the steel plate experiences the strong cooling zone once; the seventh to twenty-fourth groups of headers in the medium cooling zone are opened, and the steel plate experiences the medium cooling zone twice.

[0015] The 80-100mm ultra-thick high-strength and high-toughness lamellar tearing resistant steel plate comprises the following chemical components by weight percentage: C: ≤0.12%, Si: 0.20-0.40%, Mn: 1.42-1.52%, P: ≤0.018%, S: ≤0.005%, Nb: 0.025-0.035%, V: 0.030-0.040%, Als: 0.015-0.045%, Ti: 0.007-0.020%, Pcm: ≤0.22%, and the balance is Fe and inevitable impurities.

[0016] The 80-100mm ultra-thick high-strength and high-toughness lamellar tearing resistant steel plate has a metallographic structure of ferrite + pearlite + bainite.

[0017] The 80-100mm ultra-thick high-strength and high-toughness lamellar tearing resistant steel plate has a yield strength of greater than or equal to 420MPa, a tensile strength of greater than or equal to 520MPa, an A of greater than or equal to 22.5%, a longitudinal impact energy at -40℃ of greater than or equal to 140J, and a Z-direction performance of greater than or equal to 45%; the core performance has a yield strength of greater than or equal to 420MPa, a tensile strength of greater than or equal to 520MPa, an A of greater than or equal to 21%, and a longitudinal impact energy at -40℃ of greater than or equal to 130J.

[0018] The technical principles of the present application are as follows:

[0019] TMCP delivery 80-100mm extra-thick high strength and toughness anti-lamellar tearing steel plate, generally through controlling rolling and post-rolling rapid cooling to obtain high-density dislocation fine-grain structure can meet high strength and toughness steel mechanical properties. But in actual production process, in order to achieve complete recrystallization in high temperature recrystallization zone, it is necessary to ensure recrystallization temperature above and sufficient deformation amount during rolling, the surface temperature of the extra-thick continuous casting blank is often lower than the core temperature, the metal deformation preferentially occurs on the surface during rolling, causing large recrystallization difference in the thickness direction of the steel plate, the grain size difference is large, after subsequent non-uniform cooling and phase transformation, the room temperature structure size is uneven, and the mixed crystal is serious, which seriously affects the comprehensive performance of the core of the steel plate.

[0020] The present application adopts rapid water diversion of the blank in each rolling pass in the high temperature recrystallization zone to reduce the surface temperature of the blank, promotes the increase of the surface rolling deformation resistance, and the deformation penetrates to the core, after repeated water diversion and large reduction rolling in multiple passes, more complete recrystallization occurs in the core, no water diversion between the last two rolling passes causes complete recrystallization on the surface, resulting in uniform austenite structure in the thickness direction, and interval strong cooling and twice continuous intermediate cooling after rolling, which is beneficial to the uniform phase transformation of the extra-thick steel plate, and excellent high strength and toughness and anti-lamellar tearing performance are obtained, and in particular, the core performance of the extra-thick steel plate is significantly improved.

[0021] Compared with the prior art, the present application has the following advantages: under the existing domestic controlled rolling and controlled cooling device conditions, the present application realizes the production of 80-100mm extra-thick plate with greater difficulty through water diversion and large reduction in each recrystallization zone and segmented controlled cooling technology after rolling, the TMCP delivery steel plate produced has yield strength≥420MPa, tensile strength≥520MPa, A≥22.5%, longitudinal impact energy at-40℃≥140J, and Z-direction performance≥45%; the core performance has yield strength≥420MPa, tensile strength≥520MPa, A≥21%, and longitudinal impact energy at-40℃≥130J. The steel plate can be applied to key load-bearing parts such as weldable bridges, ships, high-rise buildings, etc., fully embodying the superiority of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Figure 1 is the metallographic structure diagram of the 100mm thick steel plate at the thickness 1 / 4 in Example 1;

[0023] Figure 2 Figure 2 is the metallographic structure diagram of the 100mm thick steel plate at the thickness 1 / 2 in Example 1;

[0024] Figure 3 Figure 3 is the metallographic structure diagram of the 100mm thick steel plate at the thickness 1 / 4 in Comparative Example 1;

[0025] Figure 4 Figure 4 is the metallographic structure diagram of the 100mm thick steel plate at the thickness 1 / 2 in Comparative Example 1. DETAILED DESCRIPTION

[0026] The 80-100mm super-thick high-toughness anti-laminated tearing steel plate with excellent core performance provided by the present application comprises the following chemical components by weight percentage: C: ≤0.12%, Si: 0.20-0.40%, Mn: 1.42-1.52%, P: ≤0.018%, S ≤0.005%, Nb: 0.025-0.035%, V: 0.030-0.040%, Als: 0.015-0.045%, Ti: 0.007-0.020%, Pcm: ≤0.22%, and the balance of Fe and inevitable impurities.

[0027] The thermomechanical rolling method for improving the core performance of the 80-100mm super-thick high-toughness anti-laminated tearing steel plate provided by the present application comprises the following steps: heating the casting blank with a walking beam furnace; the heating temperature of the continuous casting blank is 1220-1270℃, the heating time is controlled at 1.1-1.2min / mm, and the casting blank discharge temperature is ≥1150℃; then, controlled rolling is performed, and finally, controlled cooling is performed.

[0028] In the controlled rolling step, first, rolling in the recrystallization zone is performed, the rolling temperature is ≥1070℃, water cooling is performed after each pass, but water cooling is not performed between the last two passes, and the finish rolling temperature is ≥1000℃; then, rolling in the unrecrystallization zone is performed, the rolling temperature is ≤850℃, and the finish rolling temperature is 810℃±10℃.

[0029] In the controlled cooling step, first, the interval water group is opened to rapidly cool to 610-630℃ at a cooling speed of 13.5-15.5℃ / s, then, intermediate cooling is performed at a cooling speed of 6.5-8.5℃ / s, and the re-red temperature is controlled at 580±10℃.

[0030] When rolling in the recrystallization zone, the reduction rate of the last three passes is ≥12%; when rolling in the unrecrystallization zone, the cumulative deformation rate below 850℃ is ≥33%.

[0031] In the heating step, the walking beam furnace is used for heating; the heating temperature of the continuous casting blank is 1220-1270℃, the heating time is controlled at 1.1-1.2min / mm, and the casting blank discharge temperature is ≥1150℃.

[0032] In the controlled cooling step, the first-6th groups of headers are arranged in the rapid cooling zone, the water quantity of the middle cavity of the upper header is 260-270m 3 / h, and the water quantity of the lower header / the water quantity of the upper header is 1.5 / 1; the seventh-24th groups of headers are arranged in the intermediate cooling zone, the water quantity of the middle cavity of the upper header is 120-140m 3 / h, and the water quantity of the lower header / the water quantity of the upper header is 2.5 / 1.

[0033] In the control cooling step, the first, third, fifth, seventh, ninth, eleventh, thirteenth, fifteenth, seventeenth, nineteenth, twenty-first, twenty-third and twenty-fifth groups of headers are opened in the strong cooling zone, and the steel plate experiences the strong cooling zone once; the second, fourth, sixth, eighth, tenth, twelfth, fourteenth, sixteenth, eighteenth, twentieth, twenty-second and twenty-fourth groups of headers are opened in the medium cooling zone, and the steel plate experiences the medium cooling zone twice.

[0034] The application will be described in detail below with reference to the embodiments.

[0035] Embodiment 1 and Embodiment 2

[0036] The chemical components and weight percentages of the super-thick high-strength and high-toughness layered tear-resistant steel plate in Embodiment 1 and Embodiment 2 are shown in Table 1.

[0037] Table 1 (wt%)

[0038]

[0039]

[0040] The manufacturing method of the super-thick high-strength and high-toughness layered tear-resistant steel plate in Embodiment 1 and Embodiment 2 comprises the following steps: a casting blank containing the above chemical components is produced through a heating, controlled rolling and controlled cooling process, in the heating step, a walking beam furnace is used for heating; the continuous casting blank heating temperature is 1220-1270℃, the heating time is controlled at 1.1-1.2min / mm, and the blank discharge temperature is ≥1150℃; in the controlled rolling step, (1) recrystallization zone rolling: the rolling temperature is ≥1070℃, the blank is watered after each rolling, but no water cooling is performed between the last two passes, the rolling speed is 1.2-1.5m / s when watering, the ratio of the down-water amount to the up-water amount is 1.5-1.8, the up-water amount is 100-120m 3 / h, the reduction rate of the last three passes is ≥12%, and the finish rolling temperature is ≥1000℃;

[0041] (2) non-recrystallization zone rolling: the rolling temperature is ≤850℃, the cumulative deformation rate below 850℃ is required to be ≥33%, and the finish rolling temperature is 810℃±10℃.

[0042] The controlled cooling method is: the water groups in the strong cooling zone are opened at intervals, the steel plate experiences the strong cooling zone once, the cooling speed is 13.5-15.5℃ / s, and the strong cooling is performed to 610-630℃; the water groups in the medium cooling zone are continuously opened, the steel plate experiences the medium cooling zone twice, the cooling speed is 6.5-8.5℃ / s, and the re-red temperature is controlled at 580±10℃.

[0043] The specific heating and rolling process parameters of the super-thick high-strength and high-toughness layered tear-resistant steel plate in Embodiment 1 and Embodiment 2 are shown in Table 2.

[0044] Table 2

[0045]

[0046]

[0047] The specific controlled cooling process parameters of the extra-thick high strength and toughness anti-lamellar tearing steel plate in Example 1 and Example 2 are shown in Table 3 and Table 4.

[0048] Table 3 Rolling and controlled cooling process parameters of the steel plate in Example 1

[0049]

[0050] Table 4 Rolling and controlled cooling process parameters of the steel plate in Example 2

[0051]

[0052] The properties of the extra-thick high strength and toughness anti-lamellar tearing steel plate in Example 1 and Example 2 produced by the above process are shown in Table 5.

[0053] Table 5 Physical properties of the steel plate

[0054]

[0055] Note: The -40℃ longitudinal impact energy data in the table is the data obtained by testing three groups of samples produced by the same process.

[0056] Comparative Example 1 and Comparative Example 2

[0057] The chemical composition and weight percentage of the extra-thick high strength and toughness anti-lamellar tearing steel plate in Comparative Example 1 and Comparative Example 2 are shown in Table 6.

[0058] Table 6 (wt%)

[0059]

[0060]

[0061] The manufacturing method of the extra-thick high strength and toughness anti-lamellar tearing steel plate in Comparative Example 1 and Comparative Example 2 includes the following steps: producing a casting blank containing the above chemical composition by a heating and controlled rolling and controlled cooling process, in the heating step, using a walking beam furnace for heating; the continuous casting blank heating temperature is 1220-1270℃, the heating time is controlled at 1.1-1.2min / mm, and the casting blank discharge temperature is ≥1150℃; in the controlled rolling step, (1) recrystallization zone rolling: the opening rolling temperature is ≥1070℃, the final rolling temperature is ≥1000℃, and no water cooling is performed after each pass during the rolling process;

[0062] (2) non-recrystallization zone rolling: the opening rolling temperature is ≤850℃, the cumulative deformation rate below 850℃ is required to be ≥33%, and the final rolling temperature is 800-840℃.

[0063] The controlled cooling method is that the cooling device automatically waters according to the red temperature setting, automatically opens the water group, the cooling rate is 7-10 ℃ / s, and the red temperature is controlled at 590-610 ℃.

[0064] The heating, rolling and controlled cooling processes of the extra-thick high-toughness anti-lamellar tearing steel plate in Comparative Example 1 and Comparative Example 2 are shown in Table 7.

[0065] Table 7

[0066]

[0067] The properties of the extra-thick high-toughness anti-lamellar tearing steel plate in Comparative Example 1 and Comparative Example 2 are shown in Table 8.

[0068] Table 8 Steel plate actual performance

[0069]

[0070] Note: The -40 ℃ longitudinal impact energy data in the table is obtained by testing three groups of samples produced by the same process.

[0071] Comparative Example 3 and Comparative Example 4

[0072] The steel plate composition, specification, heating and controlled rolling process in Comparative Example 3 are the same as those in Comparative Example 1, and the steel plate composition, specification, heating and controlled rolling process in Comparative Example 4 are the same as those in Comparative Example 2. The controlled cooling method is that 2-5 groups of water are opened at intervals in the strong cooling zone, the cooling rate is 6.5-13 ℃ / s, the steel plate is red at 680-760 ℃ before entering the medium cooling zone, 7-10 groups of water are continuously opened in the medium cooling zone, the cooling rate is 2-6 ℃ / s, and the red temperature is 640-700 ℃. The specific process parameters are shown in Table 9.

[0073] Table 9

[0074]

[0075] The properties of the extra-thick high-toughness anti-lamellar tearing steel plate in Comparative Example 3 and Comparative Example 4 are shown in Table 10. The steel plate is thick, and it is difficult to homogenize the thickness direction structure by the conventional controlled rolling method. The cooling capacity of the interval cooling in the strong cooling zone and the continuous cooling in the medium cooling zone is insufficient, resulting in poor comprehensive performance of the steel plate.

[0076] Table 10 Steel plate actual performance

[0077]

[0078]

[0079] From the comparison of the above examples and comparative examples, it can be seen that, compared with the comparative examples, the uniform fine-grained ferrite, pearlite and bainite structure in the thickness direction is obtained in the examples by adjusting the blank recrystallization control rolling and the post-rolling segmented control cooling process, especially the fine-grained structure obtained in the core, and the banded defects are obviously reduced, as shown in Figure 1 、 Figure 2 , thus the comprehensive performance is excellent, and it is especially suitable for the use performance of high-grade bridge plates, ship plates and high-rise building steel for welding; while the grain structure in the comparative examples is not uniform, a large amount of bainite structure is produced in the surface layer due to post-rolling rapid cooling. The core deformation is difficult and the grain is coarse, and a large amount of bainite structure exists, as shown in Figure 3 、 Figure 4 . Thus the strength of the surface layer in the comparative examples is high, the toughness is poor, and the Z-direction performance is not ideal; especially the banded structure in the core is serious, and the strength and toughness cannot completely satisfy the use performance of the steel plate. The above detailed description of the hot mechanical rolling method for improving the core performance of the 80-100 mm super-thick high-strength and high-toughness anti-lamellar tearing steel plate in the reference examples is illustrative but not limiting, and a number of examples can be listed according to the limited range, thus the changes and modifications without departing from the overall concept of the present application shall fall within the protection scope of the present application.

Claims

1. A thermomechanical rolling method for improving the core properties of 80-100 mm super-thick high-toughness and lamellar-tear-resistance steel plate, characterized by, The method comprises the following steps: controlling rolling after heating the casting blank, and then controlling cooling; In the heating step, a walking beam heating furnace is used for heating; the heating temperature of the continuous casting blank is 1220-1270 DEG C, the heating time is controlled according to 1.1-1.2 min / mm, and the casting blank discharge temperature is greater than or equal to 1150 DEG C; In the controlling rolling step, first, recrystallization zone rolling is carried out, the opening rolling temperature is greater than or equal to 1070 DEG C, water cooling is carried out after each pass rolling, but water cooling is not carried out between the last two passes, and the finish rolling temperature is greater than or equal to 1000 DEG C; then, non-recrystallization zone rolling is carried out, the opening rolling temperature is less than or equal to 850 DEG C, and the finish rolling temperature is 810 DEG C plus or minus 10 DEG C; In the recrystallization zone, the water flow rate is 1.2-1.5 m / s, the ratio of the water flow rate to the upper water flow rate is 1.5-1.8, and the upper water flow rate is 100-120 m 3 / h; the reduction rate of each pass in the last three passes is greater than or equal to 12%; in the non-recrystallization zone, the cumulative deformation rate below 850°C is greater than or equal to 33%. In the controlling cooling step, first, the interval water group is opened to rapidly cool to 610-630 DEG C at a cooling speed of 13.5-15.5 DEG C / s, and then middle cooling is carried out at a cooling speed of 6.5-8.5 DEG C / s, and the re-red temperature is controlled to be 580 DEG C plus or minus 10 DEG C; In the control cooling step, the first to sixth groups of headers are arranged in the intensive cooling zone, the water quantity of the middle cavity of the upper header is 260-270 m 3 / h, the water quantity of the lower header / the water quantity of the upper header is 1.5 / 1; the seventh to twenty-fourth groups of headers are arranged in the middle cooling zone, the water quantity of the middle cavity of the upper header is 120-140 m 3 / h, the water quantity of the lower header / the water quantity of the upper header is 2.5 / 1; the second, fourth and sixth groups of headers in the intensive cooling zone are opened, the steel plate passes through the intensive cooling zone once; the seventh to twenty-fourth groups of headers in the middle cooling zone are opened, the steel plate passes through the middle cooling zone twice.

2. The thermomechanical rolling method for improving the core property of 80-100 mm super-thick high strength and toughness lamellar tearing resistant steel plate according to claim 1, characterized in that, The 80-100 mm super-thick high-strength and high-toughness anti-lamellar tearing steel plate comprises the following chemical components in percentage by weight: C: less than or equal to 0.12%, Si: 0.20-0.40%, Mn: 1.42-1.52%, P: less than or equal to 0.018%, S: less than or equal to 0.005%, Nb: 0.025-0.035%, V: 0.030-0.040%, Als: 0.015-0.045%, Ti: 0.007-0.020%, Pcm: less than or equal to 0.22%, and the balance is Fe and inevitable impurities.

3. The thermomechanical rolling method for improving the core property of 80-100 mm super-thick high strength and toughness steel plate against lamellar tearing according to claim 1, characterized in that, The 80-100 mm super-thick high-strength and high-toughness anti-lamellar tearing steel plate has a metallographic structure of ferrite + pearlite + bainite.

4. The thermomechanical rolling method for improving the core property of 80-100 mm super-thick high-strength and high-toughness lamellar tearing resistant steel plate according to claim 1, characterized in that, The 80-100 mm super-thick high-strength and high-toughness anti-lamellar tearing steel plate has a yield strength greater than or equal to 420 MPa, a tensile strength greater than or equal to 520 MPa, A greater than or equal to 22.5%, a longitudinal impact energy at-40 DEG C greater than or equal to 140 J, and Z-direction performance greater than or equal to 45%. Core Performance: yield strength greater than or equal to 420 MPa, tensile strength greater than or equal to 520 MPa, A greater than or equal to 21%, and longitudinal impact energy at-40 DEG C greater than or equal to 130 J.

5. An 80-100 mm super thick high strength and toughness lamellar tearing resistant steel plate, characterized by, Obtained by the method of any one of claims 1-4.

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