High-strength steel plate for Q490RW oil storage tank

Abstract

The invention discloses a high-strength steel plate for a Q490RW oil storage tank. The high-strength steel plate comprises chemical components in percentage by weight as follows: 0.08%-0.10% of C, 0.22%-0.32% of Si, 1.40%-1.60% of Mn, smaller than or equal to 0.013% of P, smaller than or equal to 0.005% of S, 0.22%-0.32% of Ni, 0.05%-0.15% of Mo, 0.040%-0.052% of V, 0.010%-0.020% of Ti, 0.020%-0.035% of Als and the balance of Fe. The invention also discloses a manufacturing method thereof. The performance of the steel plate meets the requirements that the yield strength is larger than or equal to 490 MPa, the tensile strength is 610-730 MPa, the percentage elongation after fracture is larger than or equal to 17%, and the ballistic work at the temperature of-20 DEG C is larger than or equal to 200 J. The impact energy of a heat affected zone at-20 DEG C is still 47J or above when the welding heat input is 100kJ / cm, and the welding performance is good.

Description

Technical Field

[0001] The invention belongs to the technical field of production of steel for oil storage tanks, and in particular relates to a Q490RW high-strength steel plate for oil storage tanks. Background Art

[0002] The construction of large storage tanks is developing rapidly, and the status of steel plates for large storage tanks as an important component cannot be ignored.

[0003] Chinese patent CN 107177802 A discloses "Quenched and tempered high-strength steel for large storage tanks and production method", which uses steelmaking, heating, rolling, quenching + tempering process to produce 12MnNiVR steel plate, and the performance of the steel plate meets the standard requirements. The shortcomings are: first, the chemical composition contains copper, which is easy to crack. Second, rapid cooling is used after rolling, and the final cooling temperature is 550℃, which deteriorates the plate shape and makes it difficult to control the plate shape. Third, the quenching temperature is high, which increases energy consumption. Fourth, the specific thickness specifications of the steel plate are not given, and the applicability is poor.

[0004] Chinese patent CN 111041366 A discloses "a quenched and tempered high-strength steel plate 12MnNi VR for large oil storage tank pressure vessels and its production method" which uses clean steel smelting, water-cooled die casting, ingot heating, ingot blanking, intermediate blank cleaning, intermediate blank heating, intermediate blank rolling, steel plate stack cooling, quenching and tempering to produce a 12MnNiVR steel plate with a maximum thickness of 65mm. The disadvantage is that it is produced by die casting process and has poor applicability.

[0005] Chinese patent CN 112921239 A discloses "a low yield ratio 12MnNiVR steel plate and its production method", which is produced by the process of molten steel smelting - LF furnace refining - RH refining - continuous casting - billet heating - rolling - heat treatment. The properties of the obtained steel plate are yield strength 520-580MPa, tensile strength 620-670MPa, yield ratio 0.86-0.89, elongation greater than 22%; -20℃ transverse V-type impact average value ≥ 260J 12MnNiVR steel plate. The disadvantage is that the thickness of the steel plate is only 10-40mm, which does not meet the use requirements. Summary of the invention

[0006] The purpose of the present invention is to provide a Q490RW high-strength steel plate for oil storage tanks, the steel plate performance meets the following requirements: yield strength ≥490MPa, tensile strength 610-730MPa, elongation after fracture ≥17%, -20℃ impact energy ≥200J, and the impact energy of the heat-affected zone after 100KJ / cm high-line energy welding is above 47J.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The invention discloses a Q490RW high-strength steel plate for oil storage tanks. The chemical components of the steel plate are as follows by weight: C: 0.08-0.10%, Si: 0.22-0.32%, Mn: 1.40-1.60%, P: ≤0.013%, S: ≤0.005%, Ni: 0.22-0.32%, Mo: 0.05-0.15%, V: 0.040-0.052%, Ti: 0.010-0.020%, Als: 0.020-0.035%, and the balance is Fe and inevitable impurities.

[0009] Furthermore, the chemical composition of the steel plate is as follows by weight: C: 0.08%, Si: 0.24%, Mn: 1.48%, P: 0.013%, S: 0.002%, Ni: 0.25%, Mo: 0.07%, V: 0.045%, Ti: 0.015%, Als: 0.022%, and the remainder is Fe and unavoidable impurities.

[0010] Furthermore, the chemical composition of the steel plate is as follows by weight: C: 0.08%, Si: 0.25%, Mn: 1.45%, P: 0.012%, S: 0.002%, Ni: 0.26%, Mo: 0.08%, V: 0.046%, Ti: 0.014%, Als: 0.025%, and the remainder is Fe and unavoidable impurities.

[0011] Furthermore, the chemical composition of the steel plate is as follows by weight: C: 0.09%, Si: 0.26%, Mn: 1.49%, P: 0.012%, S: 0.002%, Ni: 0.25%, Mo: 0.08%, V: 0.046%, Ti: 0.013%, Als: 0.023%, and the remainder is Fe and unavoidable impurities.

[0012] Furthermore, the chemical composition of the steel plate is as follows by weight: C: 0.09%, Si: 0.24%, Mn: 1.46%, P: 0.012%, S: 0.003%, Ni: 0.27%, Mo: 0.08%, V: 0.047%, Ti: 0.014%, Als: 0.023%, and the remainder is Fe and unavoidable impurities.

[0013] Furthermore, the chemical composition of the steel plate is as follows by weight: C: 0.09%, Si: 0.25%, Mn: 1.47%, P: 0.011%, S: 0.002%, Ni: 0.26%, Mo: 0.09%, V: 0.047%, Ti: 0.013%, Als: 0.024%, and the remainder is Fe and unavoidable impurities.

[0014] A method for manufacturing Q490RW high-strength steel plate for oil storage tanks, the main steps and process parameters are as follows:

[0015] S1 Hot metal pretreatment: Hot metal is desulfurized and dephosphorized by KR stirring method, S≤0.005%, P≤0.015% in hot metal;

[0016] S2 converter smelting: the temperature of molten iron entering the furnace is greater than 1260℃, ensuring that the P content of the molten steel discharged from the furnace is ≤0.010% and the S content is ≤0.004%;

[0017] S3 LF refining: LF stage accurately controls the composition of molten steel, deoxidation and alloying, S≤0.004%;

[0018] S4 RH vacuum treatment: In this treatment mode, the vacuum time is maintained for more than 20 minutes, the pure degassing time is greater than 15 minutes, and the soft blowing time is greater than 15 minutes, ensuring that the hydrogen content of the molten steel is ≤1.6ppm, the oxygen content is ≤30ppm, and the nitrogen content is ≤50ppm;

[0019] S5 slab continuous casting: dynamic soft pressure, electromagnetic stirring, protective pouring, constant casting speed process is adopted to finally produce 250mm thick continuous casting slab, the low center segregation of the slab is controlled below Class C 3.0, and the slab is pile-cooled or pit-cooled for more than 36 hours after it comes off the line;

[0020] S6 Heating: The slab is heated in a walking beam heating furnace. The atmosphere in the furnace is strictly controlled to ensure the heating temperature and heating time of the slab. The heating temperature is 1210℃~1240℃. The total time in the furnace is greater than 270min, of which the heating section time is greater than 120min and the soaking section time is greater than 30min, to ensure that the alloy elements are fully dissolved and the slab temperature is uniform.

[0021] S7 rolling and cooling: Rough rolling is carried out on a 3800mm rough rolling mill, with a start rolling temperature of more than 1170°C, and the relative reduction rate of a single pass is controlled at more than 15% for at least two passes; the start rolling thickness of the finishing rolling is 2-4 times the thickness of the finished product, the start rolling temperature of the finishing rolling is 950°C, the final rolling temperature is <810°C, and the steel plate is cooled by controlled cooling after rolling, with a final cooling temperature of 650-670°C;

[0022] S8 quenching and tempering heat treatment: the steel plate is quenched after shot blasting, the quenching heating temperature is 910℃, and the time in the furnace is 20min+t×1.4min / mm; the tempering temperature is 600℃~660℃, the tempering temperature varies with the thickness of the steel plate, and the time in the furnace is 30min+t×3.2min / mm, where t is the thickness of the steel plate, in mm.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] (1) The present invention adopts a quenching and tempering process to produce a 10-45mm thick Q490RW high-strength steel plate for oil storage tanks and a production method. The mechanical properties of the steel plate meet the following requirements: yield strength ≥490MPa, tensile strength 610-730MPa, elongation after fracture ≥17%, and impact energy at -20°C ≥200J. The actual performance is even better.

[0025] (2) The steel plate of the present invention has the characteristics of large line energy welding. It adopts the gas-electric vertical welding method. When the welding heat input is 100 kJ / cm, the impact energy of the heat-affected zone at -20°C is still above 47 J. It has good welding performance and is suitable for manufacturing key equipment components such as large storage tanks. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 This is the optical metallographic structure diagram of the steel plate near the surface in Example 2 of the present invention;

[0028] Figure 2 This is the low-magnification morphology of the impact fracture of the heat-affected zone of the 103KJ / cm welding steel plate in Example 2 of the present invention;

[0029] Figure 3 The optical metallographic structure of the heat-affected zone of the steel plate 103KJ / cm in Example 2 of the present invention;

[0030] Figure 4 This is the TEM structure of the 103KJ / cm welding heat affected zone of the steel plate in Example 2 of the present invention. DETAILED DESCRIPTION

[0031] The present invention is described in more detail below with reference to the accompanying drawings using examples. These examples are merely descriptions of the best mode of carrying out the present invention and do not impose any limitation on the scope of the present invention.

[0032] The chemical composition of the steel plate of the present invention is C: 0.08-0.10%, Si: 0.22-0.32%, Mn: 1.40-1.60%, P: ≤0.013%, S: ≤0.005%, Ni: 0.22-0.32%, Mo: 0.05-0.15, V: 0.040-0.052%, Ti: 0.010-0.020%, Als: 0.020-0.035%, and the balance is Fe and unavoidable impurities. In addition, the present invention also provides a method for manufacturing the steel plate.

[0033] The main steps and process parameters are as follows:

[0034] S1 Hot metal pretreatment: Hot metal is desulfurized and dephosphorized by KR stirring method, S≤0.005%, P≤0.015% in hot metal;

[0035] S2 converter smelting: the temperature of molten iron entering the furnace is greater than 1260℃, ensuring that the P of the molten steel out of the furnace is ≤0.010%, and S is ≤0.004%.

[0036] S3 LF refining: LF stage accurately controls the composition of molten steel, deoxidation and alloying, S≤0.004%.

[0037] S4 RH vacuum treatment: using this treatment mode, the vacuum time is maintained for more than 20 minutes, the pure degassing time is greater than 15 minutes, and the soft blowing time is greater than 15 minutes, ensuring that the hydrogen content of the de-situ molten steel is ≤1.6ppm, the oxygen content is ≤30ppm, and the nitrogen content is ≤50ppm.

[0038] S5 slab continuous casting: dynamic light pressure, electromagnetic stirring, protective pouring, constant casting speed process is adopted to finally produce 250mm thick continuous casting slabs. The low-multiple center segregation of the slabs is controlled below Class C 3.0. The slabs are pile-cooled or pit-cooled for more than 36 hours after leaving the production line.

[0039] S6 Heating: The slab is heated in a walking beam heating furnace, and the atmosphere in the furnace is strictly controlled to ensure the heating temperature and heating time of the slab, which is 1210℃~1240℃. The total time in the furnace is greater than 270min, of which the heating section time is greater than 120min and the soaking section time is greater than 30min, to ensure that the alloy elements are fully dissolved and the slab temperature is uniform.

[0040] S7 rolling and cooling: rolling adopts two-stage controlled rolling, usually called rough rolling stage and finishing rolling stage. Rough rolling is carried out in 3800mm rough rolling mill, the start rolling temperature is above 1170℃, and the relative reduction rate of single pass is controlled at more than 15% for at least two passes. The start rolling thickness of finishing rolling is 2-4 times the thickness of finished product, the start rolling temperature of finishing rolling is 950℃, the final rolling temperature is <810℃, and the steel plate is cooled by controlled cooling after rolling, and the final cooling temperature is 650-670℃.

[0041] S8 quenching and tempering heat treatment: After shot blasting, the steel plate is quenched, the quenching heating temperature is 910℃, and the time in the furnace is 20min+t×1.4min / mm. The tempering temperature is 600℃~660℃, and the tempering temperature varies with the thickness of the steel plate. The time in the furnace is 30min+t×3.2min / mm, where t is the thickness of the steel plate, in mm.

[0042] The present invention is described in detail below in conjunction with practical embodiments.

[0043] Table 1 lists the chemical composition of the examples, Table 2 lists the rolling process parameters of the examples, and Table 3 lists the heat treatment process parameters of the examples.

[0044] Table 1 Chemical composition of the present invention (wt%)

[0045] Example C Si Mn P S Ni V Ti Mo Als 1 0.08 0.24 1.48 0.013 0.002 0.25 0.045 0.015 0.07 0.022 2 0.08 0.25 1.45 0.012 0.002 0.26 0.046 0.014 0.08 0.025 3 0.09 0.26 1.49 0.012 0.002 0.25 0.046 0.013 0.08 0.023 4 0.09 0.24 1.46 0.012 0.003 0.27 0.047 0.014 0.08 0.023 5 0.09 0.25 1.47 0.011 0.002 0.26 0.047 0.013 0.09 0.024

[0046] Table 2 Rolling parameters of the embodiment of the present invention

[0047]

[0048] Table 3 Heat treatment process parameters of the embodiment of the present invention

[0049]

[0050] The mechanical properties, low temperature impact properties, and cold bending properties of the steel plate of the embodiment of the present invention were tested, and the results are shown in Table 4.

[0051] Table 4 Mechanical properties of steel plates according to the present invention

[0052]

[0053] The thickness of the test steel plate is 21mm, and single-pass forming welding is adopted. The actual linear energy of the steel plate welding reaches 103kJ / cm.

[0054] Table 5 Process parameters for high heat input welding of steel plates in Example 2

[0055]

[0056]

[0057] Table 6 Impact properties of heat affected zone of steel plate welded in Example 2

[0058]

[0059] The softening and embrittlement of the heat affected zone of the weld joint is the main problem of the weldability heat affected zone. As can be seen from the above table, after the steel plate is subjected to high-energy line gas-electrode vertical welding, the strength and low-temperature impact toughness of the weld joint still remain at a high level, indicating that the steel plate has good high-energy line weldability.

[0060] From the attached Figure 3 From the perspective of optical metallographic structure, after the steel plate is welded with a high input energy of 103kJ / cm, the grains in the coarse-grained area of ​​the welding heat affected zone are not seriously coarsened, and the structure is mainly bainite. The lath bundles of these relatively fine bainite structures are arranged regularly and the bundles are staggered. This structure has good crack arrest properties; this is also the reason why the heat affected zone of the steel plate maintains good toughness after high input energy welding.

[0061] From the attached Figure 4From the TEM structure, the grain boundaries in the coarse-grained zone are clear, the lath bainite extends from the grain boundary to the grain, and has a high dislocation density; in the fine-grained zone, there are a large number of dislocations in the ferrite grains and on the grain boundaries, and there are dispersed particles precipitated, and the dislocations and precipitated particles are intertwined.

[0062] In summary, the present invention adopts a quenching and tempering process to produce a 10-45mm thick Q490RW high-strength steel plate for oil storage tanks and a production method, the steel plate has a yield strength of ≥490MPa, a tensile strength of 610-730MPa, an elongation after fracture of ≥17%, and an impact energy of -20°C of ≥200J. The gas-electric vertical welding method is adopted, and the impact energy of the heat-affected zone at -20°C is still above 47J under a welding heat input of 100kJ / cm, and the steel plate has good welding performance and is suitable for manufacturing key equipment components such as large storage tanks.

[0063] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A Q490RW high-strength steel plate for petroleum storage tanks, characterized in that: The chemical composition of the steel plate is as follows by weight percentage: C: 0.08-0.10%, Si: 0.22-0.32%, Mn: 1.40-1.60%, P: ≤0.013%, S: ≤0.005%, Ni: 0.22-0.32%, Mo: 0.05-0.15%, V: 0.040-0.052%, Ti: 0.010-0.020%, Als: 0.020-0.035%, and the balance is Fe and unavoidable impurities.

2. The Q490RW high-strength steel plate for petroleum storage tanks according to claim 1, characterized in that: The chemical composition of the steel plate is as follows by weight: C: 0.08%, Si: 0.24%, Mn: 1.48%, P: 0.013%, S: 0.002%, Ni: 0.25%, Mo: 0.07%, V: 0.045%, Ti: 0.015%, Als: 0.022%, and the remainder is Fe and unavoidable impurities.

3. The Q490RW high-strength steel plate for petroleum storage tanks according to claim 1, characterized in that: The chemical composition of the steel plate is as follows by weight: C: 0.08%, Si: 0.25%, Mn: 1.45%, P: 0.012%, S: 0.002%, Ni: 0.26%, Mo: 0.08%, V: 0.046%, Ti: 0.014%, Als: 0.025%, and the remainder is Fe and unavoidable impurities.

4. The Q490RW high-strength steel plate for petroleum storage tanks according to claim 1, characterized in that: The chemical composition of the steel plate is as follows by weight: C: 0.09%, Si: 0.26%, Mn: 1.49%, P: 0.012%, S: 0.002%, Ni: 0.25%, Mo: 0.08%, V: 0.046%, Ti: 0.013%, Als: 0.023%, and the remainder is Fe and unavoidable impurities.

5. The Q490RW high-strength steel plate for petroleum storage tanks according to claim 1, characterized in that: The chemical composition of the steel plate is as follows by weight: C: 0.09%, Si: 0.24%, Mn: 1.46%, P: 0.012%, S: 0.003%, Ni: 0.27%, Mo: 0.08%, V: 0.047%, Ti: 0.014%, Als: 0.023%, and the remainder is Fe and unavoidable impurities.

6. The Q490RW high-strength steel plate for petroleum storage tanks according to claim 1, characterized in that: The chemical composition of the steel plate is as follows by weight: C: 0.09%, Si: 0.25%, Mn: 1.47%, P: 0.011%, S: 0.002%, Ni: 0.26%, Mo: 0.09%, V: 0.047%, Ti: 0.013%, Als: 0.024%, and the remainder is Fe and unavoidable impurities.

7. The method for manufacturing the Q490RW high-strength steel plate for petroleum storage tanks according to any one of claims 1 to 6, characterized in that: The main steps and process parameters are as follows: S1 Hot metal pretreatment: Hot metal is desulfurized and dephosphorized by KR stirring method, S≤0.005%, P≤0.015% in hot metal; S2 converter smelting: the temperature of molten iron entering the furnace is greater than 1260℃, ensuring that the P content of the molten steel discharged from the furnace is ≤0.010% and the S content is ≤0.004%; S3 LF refining: LF stage accurately controls the composition of molten steel, deoxidation and alloying, S≤0.004%; S4 RH vacuum treatment: In this treatment mode, the vacuum time is maintained for more than 20 minutes, the pure degassing time is greater than 15 minutes, and the soft blowing time is greater than 15 minutes, ensuring that the hydrogen content of the molten steel is ≤1.6ppm, the oxygen content is ≤30ppm, and the nitrogen content is ≤50ppm; S5 slab continuous casting: dynamic soft pressure, electromagnetic stirring, protective pouring, constant casting speed process is adopted to finally produce 250mm thick continuous casting slab, the low center segregation of the slab is controlled below Class C 3.0, and the slab is pile-cooled or pit-cooled for more than 36 hours after it comes off the line; S6 Heating: The slab is heated in a walking beam heating furnace. The atmosphere in the furnace is strictly controlled to ensure the heating temperature and heating time of the slab. The heating temperature is 1210℃~1240℃. The total time in the furnace is greater than 270min, of which the heating section time is greater than 120min and the soaking section time is greater than 30min, to ensure that the alloy elements are fully dissolved and the slab temperature is uniform. S7 rolling and cooling: Rough rolling is carried out on a 3800mm rough rolling mill, with a start rolling temperature of more than 1170°C, and the relative reduction rate of a single pass is controlled at more than 15% for at least two passes; the start rolling thickness of the finishing rolling is 2-4 times the thickness of the finished product, the start rolling temperature of the finishing rolling is 950°C, the final rolling temperature is <810°C, and the steel plate is cooled by controlled cooling after rolling, with a final cooling temperature of 650-670°C; S8 quenching and tempering heat treatment: the steel plate is quenched after shot blasting, the quenching heating temperature is 910℃, and the time in the furnace is 20min+t×1.4min / mm; the tempering temperature is 600℃~660℃, the tempering temperature varies with the thickness of the steel plate, and the time in the furnace is 30min+t×3.2min / mm, where t is the thickness of the steel plate, in mm.

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