High-strength container Q490RW steel plate for high heat input welding and manufacturing method of high-strength container Q490RW steel plate

Abstract

The invention relates to a high-strength container Q490RW steel plate for high heat input welding and a manufacturing method of the high-strength container Q490RW steel plate. The Q490RW steel plate is formed by smelting the following components in percentage by weight: less than or equal to 0.12% of C, 0.15%-0.40% of Si, 1.20%-1.60% of Mn, less than or equal to 0.012% of P, less than or equal to 0.005% of S, 0.15%-0.40% of Ni, 0.02%-0.06% of V, 0.002%-0.03% of Ti and the balance of Fe and inevitable impurities. The maximum thickness of the steel plate is 50 mm, and when the welding heat input is larger than 100 KJ / CM to 200 KJ / CM, the mechanical properties of a welding heat affected zone meet the conditions that the yield strength is larger than or equal to 490 MPa, the tensile strength is larger than or equal to 610 MPa, and the-20 DEG C low-temperature impact absorption energy KV2 is larger than or equal to 80 J. The production method of the steel plate comprises the steps of smelting, LF / RH refining, continuous casting, heating, rolling, rapid cooling, steel plate quenching, steel plate tempering and finished product steel plate obtaining. The Q490RW steel plate produced by the method disclosed by the invention has the characteristics of high purity, high strength, high toughness, good high heat input welding performance and the like, can be widely applied to the field of petrochemical industry, and has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of special steel smelting, and in particular relates to a high-strength Q490RW steel plate for large-line energy welding and a manufacturing method thereof. Background Art

[0002] In recent years, with the substantial increase in my country's oil consumption and the development of the petrochemical industry, the manufacturing of large-scale storage tanks for storing crude oil has also developed rapidly. Therefore, there is an urgent demand for high-strength and high-toughness Q490RW steel plates that can be welded with high line energy in a -20°C environment for the manufacture of such equipment. Traditionally, the steel grades used for such equipment are imported SPV490Q or domestic grades 12MnNiVR. However, due to the high price and long cycle of the imported product SPV490Q, it is greatly restricted. The maximum welding line energy that can be used for the domestic grade 12MnNiVR is only ≤100KJ / CM. The construction cycle of equipment such as crude oil storage tanks is long and the efficiency is low. Therefore, with the construction of more and more large crude oil storage tanks, there is an urgent need to develop domestically produced steel plates that can use high line energy welding technology. According to the design requirements, there is an urgent need for a steel grade that can meet the requirements of welding line energy > 100KJ / CM ~ 200KJ / CM, and the mechanical properties of the welding heat-affected zone are: -20℃ impact absorption energy KV2 ≥ 80J, while yield strength ≥ 490MPa and tensile strength ≥ 610MPa, for manufacturing crude oil storage tanks with a capacity of ≥ 100,000 cubic meters.

[0003] The technical quality difficulties of Q490RW steel plate, a high-strength container steel plate for high-energy input welding, are mainly manifested in: 1. Under the premise of lower carbon content and lower alloy content requirements, it is difficult to ensure that the mechanical properties of steel in the delivery state: yield strength ≥490Mpa and tensile strength ≥610MPa, -20℃ low-temperature impact absorption energy KV2 ≥80J meet the technical requirements; 2. When the welding line energy of the steel plate is greater than 100KJ / CM~200KJ / CM, the mechanical properties of the welding heat-affected zone are: -20℃ low-temperature impact absorption energy KV2 ≥ 80J, yield strength ≥ 490Mpa, and tensile strength ≥ 610MPa. It is difficult to meet the technical requirements. 3. All mechanical properties of the steel plate (including tensile properties and low-temperature impact absorption energy) meet the requirements, that is, the steel has a good match between strength and toughness, and it is difficult to meet the technical requirements. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a -20°C low-temperature steel Q490RW steel plate with a relatively simple production process, relatively low precious alloy content and high strength in response to the above-mentioned existing technology, and also relates to a production method of the steel plate.

[0005] The technical solution adopted by the present invention to solve the above problems is: a high-strength Q490RW steel plate for high-line energy welding containers, the chemical composition of the steel plate is as follows by mass percentage: C: ≤0.12%, Si: 0.15%~0.40%, Mn: 1.20%~1.60%, P≤0.012%, S≤0.005%, Ni: 0.15%~0.40%, V: 0.02%~0.06%, Ti: 0.002%~0.03%, and the balance is Fe and unavoidable impurities.

[0006] The maximum thickness of the steel plate is 50 mm.

[0007] The steel plate of the present invention adopts a chemical composition design, wherein appropriate amounts of C and Mn are solid solution strengthened; a small amount of V is added to refine the grains, and its carbonitride plays a dispersion strengthening role; titanium forms titanium oxide in the steel, which plays a role in pinning grain boundaries during high-heat welding and preventing grain growth in the heat-affected zone; Ca spheroidizes and modifies oxygen inclusions in the steel, making the casting process easier and reducing the damage caused by inclusions to the steel; and Ni improves the low-temperature toughness of the steel plate.

[0008] The roles of the components and contents in the steel plate in the present invention are: C: 0.06%~0.12%. Carbon has a significant effect on the yield strength, tensile strength and welding performance of steel. An appropriate amount of carbon content can improve the hardenability of the steel plate. It is the most direct and economical element to improve the strength of the steel plate, thereby eliminating the use of precious alloying elements Cr and Mo. However, too high a carbon content will affect the welding performance and toughness of the steel. Therefore, the carbon content range of 0.06%~0.12% is determined based on comprehensive considerations to ensure excellent mechanical properties and production economy.

[0009] Ti: 0.002% to 0.03%. Ti can increase the critical point of steel, form stable TiC particles with C, refine austenite grains, and form fine titanium oxide particles with oxygen during the deoxidation process. During high-energy-input welding, it pins the grain boundaries in the heat-affected zone to avoid coarsening of grains and improve the low-temperature impact energy of the heat-affected zone. Ti plays a key role in the high-energy-input welding performance of steel.

[0010] Si: 0.15%~0.40%, acts as a reducing agent and deoxidizer in the steelmaking process. At the same time, Si can also play a role in solid solution strengthening. However, when the content is too high, it will cause the toughness of the steel to decrease and reduce the welding performance of the steel.

[0011] Mn: 1.20%~1.60%. Manganese is low in cost and can increase the toughness, strength and hardness of steel, improve the hardenability of steel, and improve the hot working performance of steel; however, too high a manganese content can easily cause central segregation in thick steel plates.

[0012] P≤0.012%, S≤0.005%: In general, phosphorus and sulfur are harmful elements in steel, increasing the brittleness of the steel; phosphorus makes the welding performance worse, reduces the plasticity, and makes the cold bending performance worse; sulfur reduces the ductility and toughness of the steel, causing cracks during forging and rolling; therefore, the content of phosphorus and sulfur in the steel should be reduced as much as possible.

[0013] Al: 0.020~0.060%, AL is a strong deoxidizing element, after Si deoxidization, AL is used for final deoxidization, reducing the oxygen and oxide inclusion content in the steel, and improving the comprehensive performance of the steel; the total AL content of 0.020% or more is a symbol of fine-grained steel.

[0014] V: 0.02%~0.06%, the addition of vanadium is to promote the grain refinement of the rolling microstructure of the steel, which can improve the strength and toughness at the same time; vanadium can effectively refine the microstructure by inhibiting austenite recrystallization during controlled rolling, and strengthen the matrix through precipitation; it can reduce the overheating sensitivity and temper brittleness of the steel; during the welding process, the aggregation and precipitation of vanadium atoms can hinder the coarsening of austenite grains during heating, and ensure that a relatively fine heat-affected zone structure is obtained after welding, thereby improving the welding performance.

[0015] Ni: 0.15%~0.40%, nickel can improve the hardenability of the steel plate, especially in improving the toughness of the steel plate at low temperature, which can significantly lower the ductile-brittle transition temperature. Ni only forms a solid solution in the steel, and the solid solution strengthening is not obvious, mainly improving the toughness of the material during plastic deformation.

[0016] Ca: 0.001%~0.030%, calcium not only has good deoxidizing and desulfurizing ability, but also can change the long strip high-melting-point oxides and high-melting-point sulfides in the steel into spherical low-melting-point calcium salt complex inclusions with sharp angles, which can easily form crack sources at the sharp corners under low-temperature use conditions, causing the steel to crack and fail; adding an appropriate amount of calcium can improve the low-temperature toughness of the steel plate, but excessive calcium can form excess oxides in the steel, which can damage the performance of the steel, so the content of calcium must be strictly controlled.

[0017] The purpose of the present application is also to provide a production method of high-strength container steel plate Q490RW for large heat input welding, so as to improve the strength and impact toughness level of the heat-affected zone of the steel plate under the low-temperature use environment of-20 DEG C after large heat input welding.

[0018] The technical scheme of the manufacturing method of the high-strength container steel plate Q490RW for large heat input welding of the present application comprises the following steps: (1) Smelting: the molten steel is first smelted by an electric furnace or a converter, and then sent to an LF refining furnace for refining; after the molten steel is deoxidized, desulfurized, and the alloy composition meets the requirements, it is transferred to an RH furnace for vacuum degassing treatment; after the vacuum degassing treatment, Ca wire and Ti wire are added, and soft blowing is performed to make the composition of the molten steel uniform, and then the ladle is lifted and poured.

[0019] (2) Casting: produced by slab continuous casting machine, the continuous casting soft reduction is 10-18 mm.

[0020] (3) Rolling: rolled by adopting two-stage rolling process of recrystallization zone + non-recrystallization zone, the intermediate air cooling thickness is 1.5 times to 4 times of the thickness of the finished plate, the first stage rolling temperature is 930-1150 DEG C; the second stage rolling temperature is 800-950 DEG C, to obtain the steel plate. (4) Steel plate post-rolling water cooling: after the steel plate is rolled, it is rapidly water cooled, set as ACC mode, the water quantity is automatically controlled, the steel plate water inlet temperature is 650-800 DEG C, and the steel plate water outlet red return temperature is 450-650 DEG C.

[0021] (5) Steel plate heat treatment: the steel plate is subjected to quenching + tempering heat treatment, the quenching temperature is 880-930 DEG C, the holding time is 1.5 min / mm-3.0 min / mm, the steel plate is water cooled to room temperature after being discharged from the furnace; then the steel plate is subjected to tempering heat treatment, the tempering temperature is 620-680 DEG C, the holding time is 3.5 min / mm-5.0 min / mm, the steel plate is air cooled to room temperature after being discharged from the furnace, to obtain the steel plate finished product.

[0022] The primary purpose of step (1) is to obtain the specified chemical composition, and the specified contents of C, Mn, Si, P, S, Ni, V, Ti, Al and Ca jointly ensure that the steel plate can still maintain high impact toughness at -20 DEG C and yield strength and tensile strength after welding with a large linear energy of >100 KJ / CM-200 KJ / CM. Meanwhile, through step 1, the contents of P, S, N, H, O and inclusions in the steel are controlled at a very low level, which is also beneficial to the improvement of low temperature impact toughness at -20 DEG C.

[0023] The casting temperature in step (2) is 1535-1565 DEG C, and the slab is cast.

[0024] The intermediate air cooling thickness in step (3) is 1.5 times to 4 times of the thickness of the finished plate, and two-stage rolling is adopted.

[0025] The steel plate post-rolling water cooling in step (4) is set as ACC mode (rapid cooling mode), the cooling speed is 10-20 DEG C / s, the steel plate water inlet temperature is 650-800 DEG C, and the steel plate water outlet red return temperature is 450-650 DEG C.

[0026] In step (5), the steel plate is subjected to quenching and tempering heat treatment at a quenching temperature of 880°C to 930°C and a holding time of 1.5 min / mm to 3.0 min / mm. The steel plate is then water-cooled to room temperature after being removed from the furnace. The steel plate is then subjected to tempering heat treatment at a tempering temperature of 620°C to 680°C and a holding time of 3.5 min / mm to 5.0 min / mm. The steel plate is then air-cooled to room temperature after being removed from the furnace to obtain a finished steel plate. Formulating the optimal heat treatment process for the steel plate can achieve the optimal microstructure type and proportion distribution of the steel plate, and further refine the grain size, thereby facilitating high strength and excellent -20°C low-temperature toughness.

[0027] The chemical composition design of the steel plate of the present invention adopts the technology of chemically reacting titanium and oxygen in molten steel to form titanium oxide, the appropriate C content is combined with reasonable matching of Mn, Ni and V, and the Ca element is used to perform spheroidization and modification treatment on inclusions. At the same time, a controlled rolling and controlled cooling process and a quenching + tempering heat treatment process are adopted. This can ensure that the mechanical properties of the steel plate are good under the condition of relatively low usage of precious alloys, so that the steel plate has good organization, comprehensive properties and welding properties, thereby achieving excellent low-temperature toughness while taking into account the economic efficiency of production and enhancing market competitiveness.

[0028] The production method of the steel plate of the present invention adopts a controlled rolling and controlled cooling process, which solves the problem of coarse and uneven grains of the steel plate and has excellent comprehensive performance; it can also ensure that the low-temperature impact absorption energy KV2 of the steel plate in the heat-affected zone of -20°C after high-line energy welding is ≥80J, and can be used for the manufacture of various pressure vessels and storage tanks that require high-line energy welding, and has broad application prospects; the production method of the steel plate of the present invention adopts a controlled rolling and controlled cooling process and simultaneously undergoes quenching + tempering treatment to obtain a low-carbon bainite structure, and the steel plate structure is uniform and fine.

[0029] Compared with the prior art, the advantages of the present invention are: The present invention adopts a low-carbon and low-carbon equivalent design, adds approximately C: ≤0.12%, Si: 0.15%-0.40%, Mn: 1.20%-1.60%, P≤0.012%, S≤0.005%, Ni: 0.15%-0.40%, V: 0.02%-0.06%, and Ti: 0.002%-0.03%, and uses fine titanium oxide particles to pin grain boundaries to prevent grain boundary migration in the welding heat-affected zone and to feed Ca to spheroidize inclusions. A controlled rolling and controlled cooling process is used to refine the metallographic structure. A suitable quenching and tempering process is used to further refine the metallographic structure and obtain a reasonable low-carbon bainite structure, thereby ensuring that high strength and excellent low-temperature toughness match. The low-carbon bainite structure of the steel is used to ensure the high strength of the steel, and the fine titanium oxide particles in the steel are used to pin grain boundaries to prevent grain boundary migration during recrystallization after high-input welding, thereby avoiding coarsening of grains in the welding heat-affected zone and improving the low-temperature toughness of the welding heat-affected zone. The low-temperature steel Q490RW steel plate developed according to this process has a maximum thickness of 50mm and can meet the following mechanical properties of the welding heat-affected zone when the welding line energy is greater than 100KJ / CM~200KJ / CM: -20℃ low-temperature impact absorption energy KV2≥80J, yield strength≥490Mpa, and tensile strength≥610MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the metallographic structure of the Q490RW steel plate base material of Example 1 of the present invention, X100.

[0031] Figure 2 This is the metallographic structure of the Q490RW steel plate base material of Example 2 of the present invention, X500.

[0032] Figure 3 This is the metallographic structure of the Q490RW steel plate base material of Example 3 of the present invention, X500. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described in more detail with reference to the preferred embodiments of the present invention. However, these embodiments are merely descriptions of preferred implementations of the present invention and do not limit the scope of the present invention in any way. Example 1

[0034] The high-strength, low-temperature pressure vessel quenched and tempered steel plate Q490RW in this embodiment has a thickness of 12 mm. The steel is smelted from the following components in mass percentage: C: 0.06%, Si: 0.25%, Mn: 1.32%, P: 0.011%, S: 0.003%, Ni: 0.18%, V: 0.025%, Al: 0.025%, Ti: 0.010%, Ca: 0.0012%, and the balance is Fe and unavoidable impurities.

[0035] The steps of the method for producing Q490RW steel for cryogenic pressure vessels of this embodiment are as follows: (1) Smelting: The molten steel is first smelted in a converter and then sent to a LF refining furnace for refining. After deoxidation, desulfurization and alloying, it is transferred to an RH furnace for vacuum degassing. Degassing and inclusion removal are completed in the RH furnace. After vacuum degassing, Ca wire and Ti wire are added. Soft blowing is performed to make the molten steel composition uniform, and then ladle pouring is performed. (2) Continuous casting: slab continuous casting machine is used for production, and the thickness of continuous casting slab is 150mm; (3) Heating: The maximum heating temperature of the continuous casting billet is 1223℃, the soaking temperature is 1205℃, and the holding time is 3.5 hours; (4) Rolling: The steel plate was rolled using a two-stage rolling process of recrystallization + non-recrystallization. The steel thickness was 60 mm. The first stage rolling temperature was 1055°C and the final rolling temperature was 970°C. The second stage rolling temperature was 942°C and the final rolling temperature was 825°C. (5) Water cooling of steel plates after rolling: After rolling, the steel plates are rapidly water-cooled and set to ACC mode with a cooling rate of 16.5°C / second and automatic water volume control. The steel plate inlet temperature is 795°C and the steel plate outlet temperature is 586°C.

[0036] (6) Steel plate heat treatment: The steel plate is subjected to quenching and tempering heat treatment, with a quenching temperature of 890°C and a holding time of 3.0 min / mm. The steel plate is water-cooled to room temperature after being taken out of the furnace; then the steel plate is subjected to tempering heat treatment, with a tempering temperature of 675°C and a holding time of 4.0 min / mm. The steel plate is air-cooled to room temperature after being taken out of the furnace to obtain the finished steel plate.

[0037] The mechanical properties and metallographic structure of the 12mm steel plate in this example are: ⑴ Mechanical properties of steel plates The steel plate welding line energy is 126KJ / CM, and the mechanical properties of the welding heat affected zone are: yield strength 595MPa, tensile strength 665MPa, and the average transverse impact absorption energy KV2 at -20℃ is 172J.

[0038] ⑵ Metallographic structure Q490RW steel plate for low temperature pressure vessel has uniform and fine structure, and its metallographic structure is low carbon bainite with grain size of 9.0. The metallographic photos of heat affected zone of 12mm thick steel plate are shown in Figure 1 . Example 2

[0039] The low-temperature pressure vessel of this embodiment uses Q490RW steel plate with a thickness of 32 mm. The steel is melted from the following components in percentage by mass: C: 0.07%, Si: 0.28%, Mn: 1.45%, P: 0.008%, S: 0.002%, Ni: 0.25%, V: 0.035%, Ti: 0.015%, Al: 0.029%, Ca: 0.002%, and the balance is Fe and unavoidable impurities.

[0040] The steps of the method for producing Q490RW steel plate for low-temperature pressure vessels of this embodiment are as follows: (1) Smelting: The molten steel is first smelted in a converter and then sent to a LF refining furnace for refining. After deoxidation, desulfurization and alloying, it is transferred to a RH furnace for vacuum degassing. Degassing and inclusion removal are completed in the RH furnace. After vacuum degassing, Ca wire and Ti wire are added. Soft blowing is performed to make the steel liquid composition uniform, and then ladle pouring is performed.

[0041] (2) Continuous casting: The slab continuous casting machine is used for production, and the thickness of the continuous casting slab is 370mm.

[0042] (3) Heating: The maximum heating temperature of the continuous casting billet is 1242℃, the soaking temperature is 1220℃, and the holding time is 3.5 hours; (4) Rolling: The steel plate was rolled using a two-stage rolling process of recrystallization + non-recrystallization. The steel thickness was 80 mm. The first stage rolling temperature was 1065 °C and the final rolling temperature was 971 °C. The second stage rolling temperature was 844 °C and the final rolling temperature was 822 °C to obtain the steel plate. (5) Water cooling of steel plates after rolling: After rolling, the steel plates are rapidly water-cooled and set to ACC mode with a cooling rate of 14.5°C / second and automatic water volume control. The steel plate inlet water temperature is 811°C and the steel plate outlet water return temperature is 605°C.

[0043] (6) Steel plate heat treatment: The steel plate is subjected to quenching and tempering heat treatment, with a quenching temperature of 900°C and a holding time of 2.0 min / mm. The steel plate is water-cooled to room temperature after being taken out of the furnace; then the steel plate is subjected to tempering heat treatment, with a tempering temperature of 655°C and a holding time of 4.5 min / mm. The steel plate is air-cooled to room temperature after being taken out of the furnace to obtain the finished steel plate.

[0044] The mechanical properties and metallographic structure of the 32mm steel plate in this example are: (1) Mechanical properties of the heat-affected zone of steel plate welding The steel plate welding line energy is 152KJ / CM, and the mechanical properties of the welding heat affected zone are: yield strength 595MPa, tensile strength 665MPa, and the average transverse impact absorption energy KV2 at -20℃ is 164J.

[0045] (2) Metallographic structure of the heat-affected zone of steel plate welding The low-temperature pressure vessel Q490RW steel plate has uniform and fine microstructure in the welding heat affected zone, and the microstructure is low-carbon bainite with a grain size of 8.5. The microstructure of the welding heat affected zone of the 32mm-thick steel plate is shown in Figure 2 . Example 3

[0046] The low-temperature pressure vessel Q490RW steel plate of this example has a thickness of 50mm, and the steel is smelted from the following components by mass percentage: C: 0.09%, Si: 0.35%, Mn: 1.52%, P: 0.007%, S: 0.001%, Ni: 0.28%, V: 0.042%, Al: 0.035%, Ti: 0.026%, Ca: 0.002%, and the balance is Fe and unavoidable impurities.

[0047] The steps of the production method of the low-temperature pressure vessel Q490RW steel plate of this example are as follows: (1) Smelting: The molten steel is first smelted in a converter, then sent to an LF refining furnace for refining, and after completing the tasks of deoxidation, desulfurization, and alloying, transferred to an RH furnace for vacuum degassing treatment. After completing degassing and removing inclusions in the RH furnace, Ca wire and Ti wire are added, and soft blowing is performed to make the composition of the molten steel uniform, and then ladle pouring is performed.

[0048] (2) Continuous casting: The slab continuous casting machine is used for production, and the thickness specification of the continuous casting blank is 370mm.

[0049] (3) Rolling: The two-stage rolling process of recrystallization + non-recrystallization is used for rolling, and the air-cooled steel thickness is 110mm. The first-stage rolling temperature is 1030℃, and the second-stage rolling temperature is 835℃, to obtain the steel plate rough product. (4) Water cooling after steel plate rolling: After the steel plate is rolled, rapid water cooling is performed, and the ACC mode is set, with a cooling speed of 14.5℃ / s, automatic water quantity control, steel plate water inlet temperature of 791℃, and steel plate water outlet red return temperature of 562℃.

[0050] (5) Steel plate heat treatment: Quenching + tempering heat treatment is performed on the steel plate, the quenching temperature is 910℃, the holding time is 2.5min / mm, and the steel plate is water cooled to room temperature after discharging; then the steel plate is subjected to tempering heat treatment, the tempering temperature is 635℃, the holding time is 4.5min / mm, and the steel plate is air cooled to room temperature after discharging, to obtain the steel plate finished product.

[0051] The mechanical properties and microstructure of the 50mm steel plate of this example are as follows: (1) Mechanical properties of the steel plate welding heat affected zone The steel plate welding line energy is 198KJ / CM, and the mechanical properties of the steel plate welding heat affected zone are: yield strength 575MPa, tensile strength 641MPa, and average impact energy KV2 at -20℃ transverse direction 153J.

[0052] (2) Metallographic structure of the heat-affected zone of steel plate welding The heat affected zone of Q490RW steel plate for low temperature pressure vessel is uniform and fine, with a metallographic structure of low carbon bainite and a grain size of 8.5. The metallographic photo of the heat affected zone of 50mm thick steel plate is shown in Figure 3 .

[0053] Although the preferred embodiments of the present invention have been described in detail above, it should be clearly understood that various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A high strength container Q490RW steel plate for high heat input welding, characterized in that The steel plate is smelted from the following components in mass percentage: C: ≤0.12%, Si: 0.15%-0.40%, Mn: 1.20%-1.60%, P≤0.012%, S≤0.005%, Ni: 0.15%-0.40%, V: 0.02%-0.06%, Ti: 0.002%-0.03%, and the balance is Fe and unavoidable impurities.

2. The high-strength Q490RW steel plate for high-heat input welding of containers according to claim 1, characterized in that: The maximum thickness specification of the steel plate is 50mm. When the welding line energy is greater than 100KJ / CM~200KJ / CM, the mechanical properties of the welding heat affected zone are: yield strength ≥490Mpa, tensile strength ≥610MPa, and low-temperature impact absorption energy KV2 ≥80J at -20℃.

3. A method for manufacturing the high-strength Q490RW steel plate for high-heat input welding of containers according to claim 1, characterized in that: The method mainly includes: (1) Smelting: The molten steel is first smelted in an electric furnace or a converter, and then sent to the LF refining furnace for refining. After the molten steel is deoxidized, desulfurized, and the alloy composition meets the requirements, it is transferred to the RH furnace for vacuum degassing. After vacuum degassing, Ca wire and Ti wire are added, and soft blowing is performed to make the molten steel composition uniform, and then ladle pouring is performed; (2) Continuous casting: slab continuous casting machine is used for production, with a light reduction of 10 to 18 mm and a casting temperature of 1535°C to 1565°C; (3) Rolling: A two-stage rolling process of recrystallization zone + non-recrystallization zone is adopted for rolling. The rolling temperature of the first stage is 930℃~1150℃; the rolling temperature of the second stage is 800℃~950℃ to obtain a steel plate; (4) Water cooling of steel plates after rolling: After rolling, the steel plates are rapidly water-cooled and set to ACC mode with automatic water volume control. The steel plate inlet water temperature is 650℃~800℃ and the steel plate outlet water return temperature is 450℃~650℃; (5) Steel plate heat treatment: The steel plate is subjected to quenching + tempering heat treatment, the quenching temperature is 880℃~930℃, the holding time is 1.5min / mm~3.0min / mm, and the steel plate is water-cooled to room temperature after being taken out of the furnace; then the steel plate is subjected to tempering heat treatment, the tempering temperature is 620℃~680℃, the holding time is 3.5 min / mm~5.0min / mm, and the steel plate is air-cooled to room temperature after being taken out of the furnace to obtain the finished steel plate.

4. The method for manufacturing a high-strength Q490RW steel plate for high-heat input welding of a container according to claim 3, characterized in that: In step (1), phosphorus in the molten steel is removed to the maximum extent in the early stage of primary refining of the molten steel. After the temperature of the molten steel reaches above 1600°C, the primary refining is completed and the steel is tapped. The primary task of LF refining is deoxidation and desulfurization. A proper amount of aluminum wire is fed into the LF refining furnace after the ladle. During the LF refining process, the [Al] content of the molten steel is above 0.015%. Diffusion deoxidation and precipitation deoxidation are carried out in combination, and slag is quickly transformed. After good deoxidation, appropriate composition and appropriate temperature, the ladle enters RH vacuum refining. The vacuum treatment time is 10 minutes to 30 minutes. After the vacuum degassing treatment, Ca wire is added for Ca treatment, Ti wire is added, and soft blowing is used to make the molten steel composition uniform, thereby ensuring the vacuum degassing effect of the molten steel and promoting the floating removal of inclusions.

5. The method for manufacturing a high-strength Q490RW steel plate for high-heat input welding of a container according to claim 3, characterized in that: In step (2), the superheat is controlled within the range of ≤50°C, the continuous casting billet drawing speed is controlled within the range of 0.45m / min to 1.35m / min, and a dynamic light reduction process for the continuous casting billet is adopted, the reduction amount is controlled within the range of 10mm to 18mm, and the billet is cast into a slab with a center segregation of Class C below 0.5 level and a center porosity below 0.5 level.

6. The method for manufacturing a high-strength Q490RW steel plate for high-heat input welding of a container according to claim 3, characterized in that: The thickness of the steel in the intermediate drying step (3) is 1.5 to 4 times the thickness of the finished plate, and the final rolling temperature is 800°C to 860°C.

7. The method for manufacturing a high-strength Q490RW steel plate for high-heat input welding of a container according to claim 3, characterized in that: In step (4), the cooling rate of the steel plate is 10°C / second to 20°C / second.

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