A pressure vessel steel plate and a method of manufacturing the same

Abstract

A kind of pressure vessel steel plate and its preparation method, comprising the following steps: C 0.1-0.2%, Si 0.1-0.25%, Gd 0.1-0.2%, Er 0.1-0.2%, Sc 0.1-0.2%, Y 0.1-0.2%, K 0.2-0.4%, Mn 1.2-1.6%, other impurities≤0.2%, single impurity≤0.03%, the balance is Fe.The application can fully refine the crystal particles of pressure vessel steel plate and make them distribute uniformly by adding Gd, Er, Sc, Y, K and carrying out 10-15 rolling and the last solution treatment and normalizing treatment, and also can produce more austenite, so that the compressive strength of the pressure vessel steel plate reaches 550N / mm 2 Therefore, the compressive strength of the pressure vessel steel plate can be effectively improved, so as to reduce the incidence of accidents and ensure safe production.

Description

Technical Field

[0001] This invention belongs to the field of pressure vessel steel plate preparation, specifically a pressure vessel steel plate and its preparation method. Background Technology

[0002] Pressure vessels are common items in daily production and life, such as liquefied gas tanks, oxygen tanks, liquid nitrogen tanks, hydrogen tanks, and steam boilers. Because pressure vessels are often used to store high-pressure liquid gases or where large amounts of gas may be generated internally in a short period, their performance requirements are high to prevent accidents. Currently, there are many types of pressure vessel steel plates available. Since the primary function of a pressure vessel is to withstand pressure, the compressive strength of the pressure vessel steel plates is subject to strict requirements. Currently, the compressive strength of pressure vessel steel plates on the market generally reaches 400 N / mm². 2 The above-mentioned specially manufactured pressure vessel steel plates can achieve a compressive strength of 500 N / mm². 2 However, accidents involving pressure vessels still occur frequently. How to further improve the compressive strength of pressure vessel steel plates to reduce the incidence of accidents is an urgent problem to be solved. Summary of the Invention

[0003] This invention provides a pressure vessel steel plate and its preparation method to overcome the deficiencies in the prior art.

[0004] This invention is achieved through the following technical solution:

[0005] A pressure vessel steel plate, comprising: C 0.1-0.2%, Si 0.1-0.25%, Gd 0.1-0.2%, Er 0.1-0.2%, Sc 0.1-0.2%, Y 0.1-0.2%, K 0.2-0.4%, Mn 1.2-1.6%, other impurities ≤0.2%, single impurity ≤0.03%, and the balance being Fe.

[0006] A method for preparing a pressure vessel steel plate includes the following steps:

[0007] Step 1: Iron smelting. Iron ore and / or scrap iron from previous steelmaking are added to a melting furnace. The temperature is raised to 1600-1700℃, and limestone is added for slag conditioning. After the iron ore and / or scrap iron from previous steelmaking are completely melted, slag removal, desulfurization, and dephosphorization operations are performed. Before converter refining, the C content in the molten iron is 0.1-0.2%, the P content is ≤0.002%, and the S content is ≤0.003%.

[0008] Step 2: After desulfurization and dephosphorization, the molten iron is cooled to 1500-1600℃ and then operated in a converter. After the converter, the temperature is raised to 1550-1650℃, and Si, Gd, Er, Sc, Y, K, and Mn are added according to the values ​​measured before the converter. Argon gas is introduced and stirring is started to carry out metal smelting and deoxidation and dehydrogenation operations. The smelting operation lasts for 2-3 hours.

[0009] Step 3: After refining, remove slag again, then perform continuous casting and complete the quenching operation;

[0010] Step 4: After continuous casting and quenching, the steel billet is first heated and then rolled into a steel plate of a specified thickness according to requirements.

[0011] Step 5: The rolled steel plate undergoes solution treatment, and after the solution treatment is completed, it is normalized to obtain the pressure vessel steel plate.

[0012] In the method for preparing pressure vessel steel plates as described above, the amount of limestone added in step one is determined based on the analysis of the composition of iron ore and / or scrap iron generated from previous steelmaking, to ensure the efficiency of impurity removal.

[0013] In the method for preparing a pressure vessel steel plate as described above, the Si, Gd, Er, Sc, Y, and Mn elements in step two are added in the form of oxides, and the K element is added in the form of hydroxides.

[0014] In the method for preparing a pressure vessel steel plate as described above, the stirring method in step two is electromagnetic stirring.

[0015] In the method for preparing a pressure vessel steel plate as described above, the continuous casting method in step three is cladding continuous casting, the continuous casting speed is 2-3 m / min, and the cladding continuous casting operation is carried out under argon protection.

[0016] In the method for preparing a pressure vessel steel plate as described above, in step four, the steel billet after casting and quenching is first heated to 1100-1200℃ at a heating rate of 13-15℃ / min.

[0017] In the method for preparing a pressure vessel steel plate as described above, the specific rolling operation in step four is as follows: the temperature of the first rolling pass is controlled at 1050-1150℃, the temperature of the last rolling pass is controlled at 850-880℃, 10-15 rolling passes are performed according to the required thickness of the product, and the spacing between the rolling rolls for each rolling pass is adjusted according to the required thickness to ensure the accuracy of the rolling operation.

[0018] In the preparation method of pressure vessel steel plate as described above, the specific operation of solution treatment in step five is as follows: the rolled steel plate is first heated to 1000-1050℃ and held for 6-8 minutes, then heated to 1200-1250℃ and held for 1-2 hours. After the solution treatment is completed, it is air-cooled to room temperature.

[0019] In the method for preparing a pressure vessel steel plate as described above, the specific operation of the normalizing treatment in step five is as follows: the normalizing temperature is 960-1000℃, the normalizing operation time is 40-60min, and after the normalizing operation is completed, water cooling is used to cool down. When the temperature drops to 600℃, the cooling rate is controlled at 30-40℃ / s. When the temperature drops to below 600℃ but not to 300℃, the cooling rate is controlled at 60-80℃ / s. When the temperature drops to below 300℃, the maximum cooling rate is used to cool down to room temperature.

[0020] The advantages of this invention are:

[0021] 1. This invention, by adding four rare earth elements—Gd, Er, Sc, and Y—can refine the crystal particles of pressure vessel steel plates, thereby making the crystal particle distribution of pressure vessel steel plates more uniform and also facilitating the subsequent synthesis of austenite, effectively improving the pressure resistance of pressure vessel steel plates.

[0022] 2. The addition of alkali metal K in this invention can also refine the crystal particles of the pressure vessel steel plate, making the crystal particle distribution of the pressure vessel steel plate more uniform.

[0023] 3. In the production process, the present invention requires 10-15 rolling passes to further refine the crystal particles of the pressure vessel steel plate, making the crystal particle distribution of the pressure vessel steel plate more uniform. At the same time, the reduction amount of each rolling pass is small, thereby avoiding the situation where the single reduction amount affects the performance of the pressure vessel steel plate.

[0024] 4. The method of solution treatment followed by normalizing in this invention results in a more uniform distribution of crystal particles in the pressure vessel steel plate and promotes the formation of austenite, thereby improving the performance of the pressure vessel steel plate.

[0025] 5. This invention, through the addition of Gd, Er, Sc, Y, K, and Na, along with 10-15 rolling passes and a final solution treatment followed by normalizing, can fully refine and uniformly distribute the crystal particles in pressure vessel steel plates, while also generating a large amount of austenite, thereby achieving a compressive strength of 550 N / mm². 2 The above measures effectively improve the compressive strength of pressure vessel steel plates, thereby reducing the incidence of accidents and ensuring safe production. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the actual production of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] The alloy compositions of Examples 1-3 are as follows:

[0030] Example 1 0.12 0.15 0.12 0.11 0.12 0.13 0.24 1.28 0.08 Example 2 0.18 0.23 0.19 0.18 0.19 0.17 0.38 1.58 0.12 Example 3 0.16 0.18 0.16 0.15 0.17 0.16 0.31 1.39 0.06

[0031] Table 1

[0032] Example 1

[0033] The alloy composition of the obtained steel billets, excluding iron, is shown in Table 1;

[0034] Step 1: Heat the steel billet to 1100℃ at a rate of 13℃ / min;

[0035] Step 2: After heating is completed, 10 rolling passes are performed. The temperature of the first rolling pass is controlled at 1050℃, and the temperature of the last rolling pass is controlled at 850℃, finally obtaining a 10mm thick steel plate.

[0036] Step 3: The obtained steel plate is first heated to 1000℃ and held for 8 minutes, then heated to 1200℃ and held for 2 hours. After the solution treatment is completed, it is air-cooled to room temperature to complete the solution treatment.

[0037] Step 4: After solution treatment, the steel plate is held at 960℃ for 60 minutes, and then cooled by water. The cooling rate is controlled at 30-40℃ / s when the temperature drops to 600℃, and at 60-80℃ / s when the temperature drops below 300℃. When the temperature drops below 300℃, it is cooled to room temperature at the maximum cooling rate to obtain the pressure vessel steel plate.

[0038] Example 2

[0039] The alloy composition of the obtained steel billets, excluding iron, is shown in Table 1;

[0040] Step 1: Heat the steel billet to 1200℃ at a rate of 15℃ / min;

[0041] Step 2: After heating is completed, 15 rolling passes are performed. The temperature of the first rolling pass is controlled at 1150℃, and the temperature of the last rolling pass is controlled at 880℃, finally obtaining a 10mm thick steel plate.

[0042] Step 3: The obtained steel plate is first heated to 1050℃ and held for 6 minutes, then heated to 1250℃ and held for 1 hour. After the solution treatment is completed, it is air-cooled to room temperature to complete the solution treatment.

[0043] Step 4: After solution treatment, the steel plate is held at 1000℃ for 40 minutes, and then cooled by water. The cooling rate is controlled at 30-40℃ / s when the temperature drops to 600℃, and at 60-80℃ / s when the temperature drops below 300℃. When the temperature drops below 300℃, it is cooled to room temperature at the maximum cooling rate to obtain the pressure vessel steel plate.

[0044] Example 3

[0045] The alloy composition of the obtained steel billets, excluding iron, is shown in Table 1;

[0046] Step 1: Heat the steel billet to 1150℃ at a rate of 14℃ / min;

[0047] Step 2: After heating is completed, 13 rolling passes are performed. The temperature of the first rolling pass is controlled at 1100℃, and the temperature of the last rolling pass is controlled at 865℃, finally obtaining a 10mm thick steel plate.

[0048] Step 3: The obtained steel plate is first heated to 1025℃ and held for 7 minutes, then heated to 1225℃ and held for 1.5 hours. After the solution treatment is completed, it is air-cooled to room temperature to complete the solution treatment.

[0049] Step 4: After solution treatment, the steel plate is held at 980℃ for 50 minutes, and then cooled by water. The cooling rate is controlled at 30-40℃ / s when the temperature drops to 600℃, and at 60-80℃ / s when the temperature drops below 300℃. When the temperature drops below 300℃, it is cooled to room temperature at the maximum cooling rate to obtain the pressure vessel steel plate.

[0050] The performance of the pressure vessel steel plates prepared in Examples 1-3 was tested, and the results are shown in Table 2.

[0051] Example 1 556 561 683 Example 2 553 570 679 Example 3 571 588 703

[0052] Table 2

[0053] As shown in Table 2, the pressure vessel steel plates prepared in Examples 1-3 of this invention have high compressive strength, as well as good yield strength and tensile strength, which can increase the performance of the pressure vessel steel plates in actual use and reduce the probability of accidents in the pressure vessel.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pressure vessel steel plate, characterized in that: C 0.1-0.2%, Si 0.1-0.25%, Gd 0.1-0.2%, Er 0.1-0.2%, Sc 0.1-0.2%, Y 0.1-0.2%, K 0.2-0.4%, Mn 1.2-1.6%, other impurities ≤0.2%, single impurity ≤0.03%, balance Fe.

2. The method for preparing a pressure vessel steel plate as described in claim 1, characterized in that: Includes the following steps: Step 1: Iron smelting. Iron ore and / or scrap iron from previous steelmaking are added to a melting furnace. The temperature is raised to 1600-1700℃, and limestone is added for slag conditioning. After the iron ore and / or scrap iron from previous steelmaking are completely melted, slag removal, desulfurization, and dephosphorization operations are performed. Before converter refining, the C content in the molten iron is 0.1-0.2%, the P content is ≤0.002%, and the S content is ≤0.003%. Step 2: After desulfurization and dephosphorization, the molten iron is cooled to 1500-1600℃ and then operated in a converter. After the converter, the temperature is raised to 1550-1650℃, and Si, Gd, Er, Sc, Y, K, and Mn are added according to the values ​​measured before the converter. Argon gas is introduced and stirring is started to carry out metal smelting and deoxidation and dehydrogenation operations. The smelting operation lasts for 2-3 hours. Step 3: After refining, remove slag again, then perform continuous casting and complete the quenching operation; Step 4: After continuous casting and quenching, the steel billet is first heated and then rolled into a steel plate of a specified thickness according to requirements. Step 5: The rolled steel plate undergoes solution treatment, and after the solution treatment is completed, it is normalized to obtain the pressure vessel steel plate.

3. The method for preparing a pressure vessel steel plate according to claim 2, characterized in that: The amount of limestone added in step one is determined based on the analysis of the composition of iron ore and / or scrap iron generated from previous steelmaking, to ensure the efficiency of impurity removal.

4. The method for preparing a pressure vessel steel plate according to claim 2, characterized in that: In step two, the Si, Gd, Er, Sc, Y, and Mn elements are added in the form of oxides, and the K element is added in the form of hydroxides.

5. The method for preparing a pressure vessel steel plate according to claim 2, characterized in that: The stirring method in step two is electromagnetic stirring.

6. The method for preparing a pressure vessel steel plate according to claim 2, characterized in that: The continuous casting method in step three is cladding continuous casting, with a casting speed of 2-3 m / min. The cladding continuous casting operation is carried out under argon protection.

7. The method for preparing a pressure vessel steel plate according to claim 2, characterized in that: In step four, the steel billet after casting and quenching is first heated to 1100-1200℃ at a rate of 13-15℃ / min.

8. The method for preparing a pressure vessel steel plate according to claim 2, characterized in that: The specific rolling operation in step four is as follows: the temperature of the first rolling pass is controlled at 1050-1150℃, the temperature of the last rolling pass is controlled at 850-880℃, and 10-15 rolling passes are performed according to the required thickness of the product. The gap between the rolling rolls for each rolling pass is adjusted according to the required thickness to ensure the accuracy of the rolling operation.

9. The method for preparing a pressure vessel steel plate according to claim 2, characterized in that: The specific operation of the solution treatment in step five is as follows: the rolled steel plate is first heated to 1000-1050℃ and held for 6-8 minutes, then heated to 1200-1250℃ and held for 1-2 hours. After the solution treatment is completed, it is air-cooled to room temperature.

10. The method for preparing a pressure vessel steel plate according to claim 2, characterized in that: The specific operation of the normalizing treatment in step five is as follows: the normalizing temperature is 960-1000℃, the normalizing operation time is 40-60min, and after the normalizing operation is completed, water cooling is used. When the temperature drops to 600℃, the cooling rate is controlled at 30-40℃ / s. When the temperature drops to below 600℃ but not to 300℃, the cooling rate is controlled at 60-80℃ / s. When the temperature drops to below 300℃, the maximum cooling rate is used to cool down to room temperature.

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