A corrosion-resistant steel plate for a vessel having a yield strength of 690mpa and a method of manufacturing the same

Abstract

The application provides a corrosion-resistant container steel plate with a yield strength of 690 MPa and a manufacturing method thereof, the steel plate comprises the following components in percentage by weight: C: 0.03%-0.08%, Si: 0.10%-0.30%, Mn: 1.00%-2.00%, P: ≤0.015%, S: ≤0.005%, Nb: 0.10%-0.50%, Cr: 1.00%-2.00%, Mo: 0.25%-0.65%, Ni: 0.80%-1.40%, Cu: 0.50%-1.00%, Al: 0.0025%-0.0045%, and the balance is Fe and inevitable impurities; the manufacturing method comprises smelting, continuous casting, heating, rolling, and heat treatment; the steel plate produced by the application has a thickness specification of 10-50 mm, a yield strength R eL ≥700 MPa, a tensile strength R m : 800-920 MPa, an elongation A ≥18%, and a -80°C KV2 ≥100 J. After simulating post-weld heat treatment, the performance of the steel plate has a yield strength R eL ≥700 MPa, a tensile strength R m : 800-920 MPa, an A ≥18%, and a -80°C KV2 ≥100 J.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metal materials, and particularly relates to a corrosion-resistant container steel plate with a yield strength of 690 MPa and a manufacturing method thereof. BACKGROUND

[0002] Metal pressure containers belong to the equipment manufacturing industry and are a kind of metal closed containers capable of bearing high strength and high pressure, used for storing compressed gas, liquefied gas and other liquid substances with certain pressure. They are mostly used for storing some high-temperature, high-pressure, high-density and high-corrosion liquid or gas, and are commonly used in many fields such as chemical industry, military field and the like. With the rapid development of the energy industry, the state has begun to pay attention to the development of this industry and has introduced various policies to help the metal pressure container industry to obtain better development in the more fierce market competition.

[0003] Corrosion of pressure containers is divided into internal corrosion and external corrosion. Internal corrosion is the destruction caused by the electrochemical reaction of the container to the internal material medium; external corrosion is caused by the change of external environment and weather. Corrosion damage is one of the most common forms of pressure container failure. The medium in the container is mostly corrosive and often accompanied by high temperature, high pressure, toxicity and wear, and is most prone to accidents. The occurrence of corrosion has the characteristics of being slow and silent, and many accidents are caused by the failure to discover the corrosion of the container in time. Therefore, higher demands are put forward for corrosion-resistant container steel plates.

[0004] Corrosion-resistant container steel plates are generally subjected to quenching and tempering heat treatment processes to make the steel plates have good-80℃ low-temperature impact toughness, high strength, good hydrogen resistance and excellent comprehensive mechanical properties, and after simulated post-weld heat treatment, the mechanical properties still meet the requirements.

[0005] For example, the patent document "N08825 composite steel plate for high corrosion-resistant container and preparation method thereof" (CN112721349A) has a base layer chemical composition of C≤0.20%, Si≤0.55%, Mn 0.5-1.7%, Nb≤0.050%, V≤0.050%, Ti≤0.030%, Alt≥0.020%, P≤0.025%, S≤0.010%, Cu+Ni+Cr+Mo≤0.70%, and the composite layer uses N08825. The disadvantages of this composite plate are low strength, long production cycle and poor corrosion resistance of the base layer carbon steel.

[0006] In the patent document "Super Austenitic Stainless Steel Composite Plate for High Corrosion Resistant Container and Preparation Method" (CN108723712A), a super austenitic stainless steel composite plate for high corrosion resistant container with good metallurgical bonding is prepared, effectively solving the problem of corrosion resistance of the super austenitic stainless steel in the composite plate online process, and reducing the drilling and vacuumizing procedures in the blank preparation process. However, the production cycle is relatively long, and the use of the corrosion resistance of the composite austenitic stainless steel improves the overall corrosion resistance of the container, resulting in high cost.

[0007] In the patent document "Corrosion Resistant Steel for Railway Tank Car and Production Method Thereof" (CN111748743A), the chemical composition is designed as follows: C 0.14-0.18%, Si 0.15-0.40%, Mn 1.25-1.65%, P≤0.020%, S≤0.005%, Cu 0.15-0.30%, Ni 0.20-0.40%, V 0.050-0.080%, Nb 0.010-0.020%, Ti 0.008-0.020%, Sb 0.05-0.15%, the balance of Fe and other elements. The disadvantage is that the P content in the steel plate is relatively high, which is easy to generate inclusions, the low temperature impact toughness is only guaranteed at-50℃, and the strength is low, which is difficult to overcome the use environment.

[0008] Therefore, in view of the above situation, a new type of high strength steel material is needed to be developed by improving the manufacturing method and new component design, and a corrosion resistant container steel plate with yield strength of 690MPa and its manufacturing method are developed. SUMMARY

[0009] The purpose of the present application is to overcome the above problems and deficiencies and provide a corrosion resistant container steel plate with yield strength of 690MPa and its manufacturing method, which eliminates the damage of blocky ferrite to the strength of the steel plate.

[0010] The purpose of the present application is achieved as follows:

[0011] A corrosion resistant container steel plate with yield strength of 690MPa, the composition of the steel plate is as follows in terms of weight percentage: C: 0.03% to 0.08%, Si: 0.10% to 0.30%, Mn: 1.00% to 2.00%, P: ≤0.015%, S: ≤0.005%, Nb: 0.10% to 0.50%, Cr: 1.00% to 2.00%, Mo: 0.25% to 0.65%, Ni: 0.80% to 1.40%, Cu: 0.50% to 1.00%, Al: 0.0025% to 0.0045%, the balance being Fe and unavoidable impurities.

[0012] The Nb / C in the steel plate is 4 to 11.

[0013] The microstructure of the steel plate is bainite tempering structure, and the size of carbide in the structure is 2-4 μm.

[0014] The thickness of the steel plate is 10-50 mm, ReL≥700 MPa, Rm: 800-920 MPa, A≥18%, -80 ℃ KV2≥100 J, CLR≤5%, CTR≤1.5%, and CSR≤0.5%.

[0015] The component design reasons of the present application are as follows:

[0016] C forms various types of carbides or forms solid solution in the steel to play a strengthening role, and is an element directly improving the strength of the steel plate. For the tempered steel plate, too high C content will result in poor toughness and plasticity of the steel, and affect the corrosion resistance of the steel plate. Therefore, in order to ensure that the steel plate has good low-temperature impact toughness, high strength and excellent corrosion resistance during use, and to ensure that the CEV is low enough, the C content is limited to 0.03%-0.08%.

[0017] Si has the effects of deoxidation and solid solution strengthening in the steel, improves the yield strength of the steel plate, and appropriate Si can improve the toughness and hardenability of the steel plate, reduce the ductile-brittle transition temperature, and also can improve the oxidation resistance and high-temperature corrosion resistance of the steel. Therefore, the Si content is limited to 0.10%-0.30%.

[0018] Mn improves the strength and toughness in the steel by replacement, grain refinement and increase of ferrite content, and is dissolved in the Fe matrix to improve the strength of the steel plate; with the increase of Mn content, the austenite structure in the steel can be stabilized, the critical cooling rate can be reduced, and the hardenability and tempering stability can be significantly improved. Therefore, Mn is limited to 1.00%-2.00%.

[0019] P is a harmful element in the steel, which is harmful to low-temperature impact toughness and is also an element prone to segregation. In the present application, P is controlled in a lower range, and therefore the content of P is controlled to be less than 0.015%.

[0020] S is also a harmful element in the steel, which is easy to form MnS in the steel and become a source of crack formation in subsequent processing, and has a great influence on the toughness and corrosion resistance of the steel. Therefore, S is controlled to be less than 0.005%.

[0021] Cr is a main element in the present application, which can improve the toughness and hardenability of the steel plate, and higher Cr content can make the steel plate have good corrosion resistance and oxidation resistance, and promote the generation of bainite, a low-temperature phase change product; in the quenching and tempering heat treatment process, the Cr-containing carbide precipitated can be dissolved in the matrix to refine the grain size. Therefore, the content of Cr in the present application is controlled to be between 1.00% and 2.00%.

[0022] Mo is the main element in this invention. It can improve the strength, toughness, and hardenability of steel. During the two-stage rolling process, it can shrink the austenite phase region, promote bainite transformation, and generate Mo-containing carbides that can inhibit ferrite formation. Through solid solution strengthening, it dissolves in austenite and ferrite to improve the yield strength of steel and enhance the tempering resistance of steel plates. After quenching and tempering heat treatment, Mo can form stable carbides, improving the corrosion resistance of steel and also improving the low-temperature toughness of steel. Therefore, the Mo content is between 0.25% and 0.65%.

[0023] Ni is the main element in this invention. As a key element for stabilizing austenite, it dissolves in austenite and ferrite, improving the strength of steel and refining the grain structure. Ni can significantly improve the low-temperature toughness of steel plates after quenching and tempering heat treatment, and also improve the strength and elongation of the steel. However, due to the high cost of Ni, it also makes it difficult to remove the iron oxide scale from the steel plate, further increasing costs. Therefore, the Ni content is limited to between 0.80% and 1.40%.

[0024] Nitrogen (Nb) is the main element in this invention. In steel, it can suppress austenite recrystallization during rolling, increase the dislocation density within the austenite body, promote grain refinement, and improve the strength and toughness of quenched and tempered steel plates. During controlled rolling, Nb can precipitate large amounts of Nb-containing carbonitrides at grain boundaries and dislocations, resulting in precipitation strengthening. Furthermore, increasing the Nb content can fix the carbon in alloy steel, generating stable carbides and mitigating the harmful effects of carbon on the corrosion resistance of the steel plate. Therefore, Nb is limited to 0.10%–0.50%. However, as the carbon content increases, more Nb-containing carbides precipitate in the steel, and the carbide size increases, weakening the dispersion strengthening effect and leading to a decrease in strength. Therefore, the Nb / C ratio is limited to 4–11.

[0025] As an element that expands the austenite region, Cu's solubility in ferrite decreases with decreasing temperature. Through appropriate heat treatment, it can undergo precipitation strengthening in the microstructure. Furthermore, Cu can help steel plates obtain good low-temperature toughness and improve the corrosion resistance of steel. Therefore, the Cu content is limited to 0.50% to 1.00%.

[0026] Al acts as a primary deoxidizer in steel, fixing nitrogen (N) elements, refining grains, and improving steel toughness. Appropriate Al content enhances the steel's oxidation resistance and resistance to high-temperature gases, while excessive Al content negatively impacts the steel's hot plasticity. Therefore, the Al content is limited to 0.0025%–0.0045%.

[0027] The second technical solution of the present invention is to provide a method for manufacturing a corrosion-resistant container steel plate with a yield strength of 690MPa, including smelting, continuous casting, heating, rolling and heat treatment;

[0028] Smelting: Hot metal pretreatment is adopted, with hot metal temperature of 1400~1450℃; during refining treatment, LF time is 40~55min, RH time is 40~55min, and vacuum degree is ≤5.0mbar.

[0029] Continuous casting: The tundish steel pouring temperature is 1350–1410℃, with a preferred light reduction technique, the reduction being controlled at 3–5 mm; the billet pulling speed is 0.55–0.75 m / min, the secondary cooling water flow rate is 4500–5000 L / min, the superheat is 15–25℃, and the straightening temperature is 980–1050℃. The light reduction technique involves slightly reducing the billet near the point of solidification to reduce center segregation.

[0030] Heating: The heating of the continuously cast billet is divided into a preheating section, a heating section, and a soaking section; the temperature range of the heating section is 1190-1250℃; the temperature range of the soaking section is 1170-1230℃; the total time in the furnace is 200-300 minutes. By heating the billet in three stages, the core temperature of the billet reaches 1170-1230℃, ensuring that the billet microstructure is fully austenitic.

[0031] Rolling: After the billet exits the furnace, a two-stage controlled rolling and cooling technology is adopted. In the roughing stage, the initial rolling temperature is 1100-1150℃, the roll speed is 0.4-0.6m / s, and the single-pass reduction rate is 15%-20%. In the finishing stage, the initial rolling temperature is 880-930℃, the final rolling temperature is 770-820℃, the roll speed is 0.5-0.6m / s, and the single-pass reduction rate is 10%-15%. In the cooling stage, the initial cooling temperature is 740-800℃, and the final cooling temperature is 400-450℃. After cooling, the steel plates are stacked and slowly cooled at 400-450℃ for 1000-1200min. Through two-stage rolling with high reduction and slow roll speed, the deformation storage energy in the microstructure is increased, the time for dynamic recrystallization is prolonged, and the grains are refined. By controlling the cooling, the ferrite transformation is suppressed, and the bainite transformation is promoted to be complete.

[0032] Ideally, the steel plate should be straightened after cooling, with the straightening speed controlled at 1.3-2.0 m / s. Straightening the steel plate eliminates residual stress generated inside the steel plate due to cooling, ensuring a good plate shape.

[0033] Heat treatment: After slow cooling in stacks, the steel plates undergo quenching and tempering heat treatment. The quenching temperature is 930–960℃, and the holding time is 40–70 min; the tempering temperature is 680–720℃, and the holding time is 100–250 min. After being removed from the furnace, the plates are air-cooled to room temperature to ensure that the steel plate microstructure fully transforms into a bainitic tempered microstructure. Through quenching and tempering heat treatment, the steel plate microstructure becomes uniform, resulting in a bainitic tempered microstructure. This heat treatment improves the mechanical properties of the steel plate.

[0034] The beneficial effects of this invention are as follows:

[0035] 1. In terms of chemical composition, the hardenability of steel plates is increased by adding sufficient amounts of Cr and Ni elements to the traditional C-Mn low alloy steel. The higher Cr content enables the steel plate to have good corrosion resistance and oxidation resistance, while promoting the formation of bainite, a low-temperature phase transformation product. Ni is the main element for stabilizing austenite and can exist in austenite and ferrite in solid solution with Fe, which improves the strength of steel, refines grains, and can improve the low-temperature toughness of offline quenched and tempered steel plates, as well as improve the strength and elongation of quenched and tempered steel plates. Mo can improve the strength, toughness, hardenability and tempering resistance of steel, promote bainite transformation during two-stage rolling, and the formation of Mo-containing carbides can inhibit the formation of ferrite. In addition, the corrosion resistance of steel plates is improved by adding Cu elements.

[0036] 2. The manufacturing method of this invention is reasonable. By adopting two-stage rolling and controlled cooling, combined with tempering heat treatment, it is ensured that the finished product has a bainitic tempered structure with carbide size between 2-4μm and uniform distribution. This eliminates the damage of ferrite to the strength of the steel plate, so that the steel plate has excellent strength and toughness. Even after simulated welding heat treatment, it still has excellent strength and toughness.

[0037] 3. The steel plate of this invention has a thickness of 10-50mm and a yield strength R. eL ≥700MPa, tensile strength R m 800~920MPa, elongation A≥18%, KV2≥100J at -80℃. Simulated post-weld heat treatment properties of steel plate yield strength R. eL ≥700MPa, tensile strength R m :800~920MPa, A≥18%, -80℃KV2≥100J.

[0038] 4. In this invention, the sample is immersed in solution A (5% NaCl + 0.5% glacial acetic acid solution), nitrogen is introduced for 60-80 minutes, the immersion time is 96-98 hours, the immersion solution temperature is 25±3℃, CLR≤5%, CTR≤1.5%, and CSR≤0.5%. Detailed Implementation

[0039] The present invention will be further illustrated below through examples.

[0040] (1) Heating: The heating of the continuously cast billet is divided into a preheating section, a heating section and a soaking section; the temperature range of the heating section is 1190~1250℃; the temperature range of the soaking section is 1170~1230℃; the total time in the furnace is 200~300min;

[0041] (2) Rolling: After the billet exits the furnace, a two-stage controlled rolling and cooling technology is adopted. In the roughing stage, the initial rolling temperature is 1100-1150℃, the roll speed is 0.4-0.6m / s, and the single-pass reduction rate is 15%-20%; in the finishing stage, the initial rolling temperature is 880-930℃, the final rolling temperature is 770-820℃, the roll speed is 0.5-0.6m / s, and the single-pass reduction rate is 10%-15%; in the cooling stage, the initial cooling temperature is 740-800℃, and the final cooling temperature is 400-450℃; after cooling, the steel plates are stacked and slowly cooled at a temperature of 400-450℃ for 1000-1200min.

[0042] (3) Heat treatment: After stacking and slow cooling, the steel plates are subjected to quenching and tempering heat treatment, wherein the quenching temperature is 930~960℃ and the holding time is 40~70min; the tempering temperature is 680~720℃ and the holding time is 100-250min. After being taken out of the furnace, they are air-cooled to room temperature.

[0043] Further; Smelting: Iron pretreatment is adopted, with iron temperature of 1400~1450℃; during refining treatment, LF time is 40-55min, RH time is 40-55min, and vacuum degree is ≤5.0mbar.

[0044] Further; Continuous casting: tundish steel pouring temperature 1350~1410℃, billet pulling speed 0.55~0.75m / min, secondary cooling water 4500~5000L / min, superheat 15~25℃, straightening temperature 980~1050℃.

[0045] Furthermore, a light reduction technique is adopted during the continuous casting process, with the reduction amount controlled at 3-5 mm.

[0046] Furthermore, after rolling and before slow cooling in the stack, straightening is also included, with the straightening speed controlled at 1.3-2.0 m / s.

[0047] According to the component ratio of the technical solution, the present invention involves smelting, continuous casting, heating, rolling, and heat treatment. The composition of the steel in the present invention is shown in Table 1. The main process parameters for smelting and casting of the steel in the present invention are shown in Table 2. The main process parameters for heating and rolling of the steel in the present invention are shown in Table 3. The process parameters for cooling, slow cooling, and heat treatment of the steel in the present invention are shown in Table 4. The properties of the steel in the present invention are shown in Table 5. The mechanical properties of the steel after post-weld heat treatment are shown in Table 6.

[0048] Table 1. Composition (wt%) of steel in embodiments of the present invention

[0049] Examples C Si Mn P S Nb Cr Mo Ni Cu Al Nb / C 1 0.03 0.10 1.00 0.001 0.001 0.10 1.00 0.28 0.80 0.50 0.0027 3.3 2 0.06 0.20 1.37 0.014 0.004 0.45 1.92 0.62 1.40 0.92 0.0043 7.5 3 0.07 0.28 1.87 0.015 0.004 0.38 1.36 0.58 1.34 0.92 0.0044 5.4 4 0.04 0.23 1.55 0.004 0.002 0.42 1.74 0.56 1.28 0.52 0.0027 10.5 5 0.03 0.25 1.86 0.003 0.001 0.29 1.69 0.51 1.13 0.94 0.0044 9.7 6 0.05 0.15 1.07 0.015 0.005 0.35 1.72 0.48 1.03 0.78 0.0029 7.0 7 0.06 0.16 1.18 0.006 0.002 0.28 1.66 0.40 1.02 0.71 0.0028 4.7 8 0.03 0.18 1.19 0.012 0.003 0.21 1.25 0.53 1.26 0.81 0.0033 7.0 9 0.05 0.16 1.13 0.012 0.003 0.29 1.18 0.39 0.81 1.00 0.0045 5.8 10 0.07 0.25 1.79 0.005 0.002 0.37 1.47 0.52 1.16 0.62 0.0028 5.3 11 0.08 0.30 2.00 0.007 0.002 0.46 1.89 0.4 0.82 0.91 0.0038 5.8 12 0.03 0.23 1.61 0.005 0.002 0.17 1.56 0.49 1.03 0.77 0.0029 5.7 13 0.04 0.19 1.31 0.011 0.003 0.29 1.94 0.38 0.81 0.73 0.0028 7.3 14 0.05 0.24 1.71 0.004 0.001 0.39 2.00 0.42 1.02 0.90 0.0036 7.8 15 0.06 0.28 1.95 0.012 0.004 0.46 1.85 0.65 1.40 0.86 0.0035 7.7

[0050] Table 2 Main process parameters for steel smelting and casting in the embodiments of the present invention.

[0051]

[0052] Table 3 Main process parameters for steel heating and rolling in the embodiments of the present invention.

[0053]

[0054] Table 4. Process parameters for steel cooling, slow cooling, and heat treatment in embodiments of the present invention.

[0055]

[0056] Table 5 Properties of the steel in the embodiments of the present invention

[0057]

[0058] Note: The sample was immersed in solution A, with nitrogen gas introduced for 60–80 min, for a total immersion time of 96–98 h, at a solution temperature of 25 ± 3 °C. Solution A was a mixture of 5% NaCl and 0.5% glacial acetic acid.

[0059] Table 6 Mechanical properties of steel after post-weld heat treatment in embodiments of the present invention

[0060]

[0061] Note: The heat treatment temperature for mold welding is 550-650℃, and the holding time is 120-480min.

[0062] The steel plate produced using this invention has a bainitic tempered microstructure. The steel plate has a thickness of 10–50 mm and a yield strength R0. eL ≥700MPa, tensile strength R m 800~920MPa, elongation A≥18%, KV2≥100J at -80℃. Simulated mechanical properties of steel plate after post-weld heat treatment: yield strength R. eL ≥700MPa, tensile strength R m 800~920MPa, elongation A≥18%, KV2≥100J at -90℃.

[0063] To illustrate the present invention, the present invention has been appropriately and sufficiently described above through embodiments. The above embodiments are only for illustrating the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Any modifications, equivalent substitutions, improvements, etc., should be included within the protection scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A corrosion-resistant steel plate for containers with a yield strength of 690 MPa, characterized in that, The steel plate has the following composition by weight percentage: C: 0.03%–0.08%, Si: 0.10%–0.30%, Mn: 1.00%–2.00%, P: ≤0.015%, S: ≤0.005%, Nb: 0.10%–0.50%, Cr: 1.00%–2.00%, Mo: 0.25%–0.65%, Ni: 0.80%–1.40%, Cu: 0.50%–1.00%, Al: 0.0025%–0.0045%, with the balance being Fe and unavoidable impurities; the steel plate has a thickness of 10–50 mm, a yield strength ReL ≥ 700 MPa, a tensile strength Rm: 800–920 MPa, an elongation A ≥ 18%, and a KV2 ≥ 100 J at -80℃.

2. The corrosion-resistant container steel plate with a yield strength of 690 MPa according to claim 1, characterized in that, The Nb / C ratio in this steel plate is 4 to 11.

3. The corrosion-resistant container steel plate with a yield strength of 690 MPa according to claim 1, characterized in that, The microstructure of the steel plate is bainitic tempered structure, with carbide size of 2-4 μm.

4. The corrosion-resistant container steel plate with a yield strength of 690 MPa according to claim 1, characterized in that, The steel plate was immersed in solution A, which consisted of 5% NaCl and 0.5% glacial acetic acid, with nitrogen gas introduced for 60-80 minutes and the immersion time for 96-98 hours. The immersion solution temperature was 25±3℃, and the following parameters were specified: CLR≤5%, CTR≤1.5%, and CSR≤0.5%.

5. A method for manufacturing a corrosion-resistant container steel plate with a yield strength of 690 MPa as described in any one of claims 1-4, comprising smelting, continuous casting, heating, rolling, and heat treatment; characterized in that: (1) Heating: The heating of the continuously cast billet is divided into a preheating section, a heating section and a soaking section; the temperature range of the heating section is 1190~1250℃; the temperature range of the soaking section is 1170~1230℃; the total time in the furnace is 200~300min; (2) Rolling: After the billet exits the furnace, a two-stage controlled rolling and cooling technology is adopted; the roughing stage starts at a rolling temperature of 1100-1150℃, roll speed is 0.4-0.6m / s, and single-pass reduction is 15%-20%; the finishing stage starts at a rolling temperature of 880-930℃, finishes at a rolling temperature of 770-820℃, roll speed is 0.5-0.6m / s, and single-pass reduction is 10%-15%; the cooling stage starts at a cooling temperature of 740-800℃, and finishes at a cooling temperature of 400-450℃; after cooling, the steel plates are stacked and slowly cooled at a temperature of 400-450℃ for 1000-1200min. (3) Heat treatment: After stacking and slow cooling, the steel plates are subjected to quenching and tempering heat treatment, wherein the quenching temperature is 930~960℃ and the holding time is 40~70min; the tempering temperature is 680~720℃ and the holding time is 100~250min; after being taken out of the furnace, they are air-cooled to room temperature.

6. The method for manufacturing a corrosion-resistant container steel plate with a yield strength of 690 MPa according to claim 5, characterized in that: Smelting: Hot metal pretreatment is adopted, with hot metal temperature of 1400~1450℃; during refining treatment, LF time is 40~55min, RH time is 40~55min, and vacuum degree is ≤5.0mbar.

7. The method for manufacturing a corrosion-resistant container steel plate with a yield strength of 690 MPa according to claim 5, characterized in that: Continuous casting: The tundish steel pouring temperature is 1350~1410℃, light reduction technology is adopted, the billet pulling speed is 0.55~0.75m / min, the secondary cooling water is 4500~5000L / min, the superheat is 15~25℃, and the straightening temperature is 980~1050℃.

8. The method for manufacturing a corrosion-resistant container steel plate with a yield strength of 690 MPa according to claim 7, characterized in that: The continuous casting process employs a light reduction technique, with the reduction amount controlled between 3 and 5 mm.

9. The method for manufacturing a corrosion-resistant container steel plate with a yield strength of 690 MPa according to claim 5, characterized in that: After rolling and before slow cooling in the stack, straightening is also included, with the straightening speed controlled at 1.3 to 2.0 m / s.

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