High-pressure-resistant hydrogen pipeline steel as well as preparation method and application thereof

Abstract

The invention relates to the technical field of pipeline steel production, and provides high-pressure-resistant hydrogen pipeline steel as well as a preparation method and application thereof.The high-pressure-resistant hydrogen pipeline steel comprises the following chemical components in percentage by mass: 0.02%-0.05% of C, 0.15%-0.45% of Si, 1.0%-1.4% of Mn, 0.15%-0.4% of Ni, 0.1%-0.4% of Mo, 0.03%-0.06% of Nb, 0.01%-0.04% of Ti, 0.04%-0.15% of V, less than or equal to 0.015% of P, less than or equal to 0.005% of S and the balance of Fe and other inevitable impurities. The method comprises the following steps: smelting and casting into a blank; heating the casting blank; two-stage rolling; cooling is performed; performing heat preservation treatment. According to the patent technology, the yield strength ranges from 510 MPa to 530 MPa, the tensile strength ranges from 570 MPa to 630 MPa, the ductility under the 10 MPa hydrogen environment is larger than 20%, and the hydrogen embrittlement sensitivity is smaller than 17%.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline steel production, and in particular to a high-pressure hydrogen resistant pipeline steel, a preparation method and an application thereof. Background Art

[0002] As a zero-carbon clean energy, hydrogen energy has an increasingly prominent application value in the world's energy transformation. Countries and regions such as the United States, Japan, and the European Union have successively formulated hydrogen energy development strategies or plans to strongly support the development of the hydrogen energy industry. my country has made a full-scale layout in basic research, applied research, and demonstration applications, covering four links: hydrogen production, storage, transportation, and use.

[0003] The transportation of hydrogen is an important part of hydrogen energy utilization, and safe and efficient hydrogen transportation technology is the prerequisite for the large-scale commercial development of hydrogen energy. For large-scale centralized hydrogen production and long-distance hydrogen transportation, pipeline transportation is the most economical and efficient way. According to statistics, the total length of hydrogen pipelines worldwide is less than 4,600 kilometers, and the development and application of hydrogen transportation pipelines at home and abroad are still in their infancy.

[0004] At present, the steel used in existing hydrogen pipelines is mainly low-grade pipeline steel with low strength, such as X42 and X52 steel grades, and high-grade hydrogen pipeline steel of X70 and above has not yet been involved. This is because generally speaking, the higher the strength of pipeline steel, the higher the sensitivity to hydrogen-induced cracking, and the performance of pipeline steel will further deteriorate in a high-pressure hydrogen environment. However, the existing high-strength grade pipeline steel cannot meet the requirements of high-pressure hydrogen transmission. Therefore, it is urgent to develop pipeline steel that meets the requirements of high-pressure hydrogen pipeline transportation. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a high-pressure hydrogen pipeline steel, a preparation method and an application thereof, which has excellent resistance to high-pressure hydrogen embrittlement while ensuring high strength and toughness.

[0006] The present invention adopts the following technical solution:

[0007] In one aspect, the present invention provides a method for preparing high-pressure hydrogen pipeline steel, characterized in that the method comprises:

[0008] S1. Prepare, smelt and cast into billets according to the set element mass percentage; the elements include C, Si, Mn, Ni, Mo, Nb, Ti and V:

[0009] S2, heating the ingot to a first temperature and keeping the temperature for a certain period of time;

[0010] S3, performing thermomechanical controlled rolling on the ingot, performing a first stage rolling at a second temperature, controlling the rolling reduction; and then performing a second stage rolling at a third temperature, controlling the rolling reduction;

[0011] S4, cooling to the fourth temperature after hot rolling for heat preservation treatment, and then air cooling to room temperature to obtain high-pressure hydrogen pipeline steel;

[0012] The first temperature, the second temperature, the third temperature and the fourth temperature decrease in sequence.

[0013] Any possible implementation as described above, further provides an implementation, in step S1, the element mass ratio is: C: 0.02-0.05%, Si: 0.15-0.45%, Mn: 1.0-1.4%, Ni: 0.15-0.4%, Mo: 0.1-0.4%, Nb: 0.03-0.06%, Ti: 0.01-0.04%, V: 0.04-0.15%, P: ≤0.015%, S: ≤0.005%, and the remainder is Fe.

[0014] The basic functions of the main elements in the scheme of the present invention are as follows:

[0015] C: C mainly exists in the form of solid solution and precipitated carbides, which plays a strengthening role. However, too high C content will affect weldability and toughness. Therefore, the C content is controlled to 0.02-0.05%.

[0016] Si: Si improves the strength of pipeline steel in the form of solid solution strengthening, but a high Si content will reduce toughness. Therefore, the Si content is controlled to 0.15-0.45%;

[0017] Mn: Mn improves the strength of pipeline steel through solid solution strengthening, compensating for the strength loss caused by the reduction of C content. However, excessive Mn content may cause a MnS segregation zone in the center of the steel plate, which has an adverse effect on the mechanical properties and hydrogen embrittlement resistance of the steel. Therefore, the Mn content is controlled to 1.0-1.4%;

[0018] Ni: Ni improves the toughness of pipeline steel on the one hand, and on the other hand, can improve hardenability, so the Ni content is controlled to be 0.15-0.4%;

[0019] Mo: Mo can improve the hardenability of pipeline steel, and the proper amount of Mo segregation at the grain boundary can play a role in strengthening the grain boundary. Therefore, the Mo content is controlled to be 0.1-0.4%;

[0020] Nb: Nb plays a role in refining grains during high temperature rolling through solid solution drag to improve the strength and toughness of pipeline steel. Therefore, the Nb content is controlled to be 0.03-0.06%;

[0021] Ti: Ti is added mainly to fix the N element in the steel, so the Ti content is controlled to be 0.01-0.04%;

[0022] V: V has a high precipitation strengthening effect. When kept at 550-670℃ for a certain period of time, a large amount of VC precipitation phase can be formed, which can not only provide strength increment, but also VC, as an excellent irreversible hydrogen trap, can greatly improve the hydrogen embrittlement resistance. Therefore, the V content is controlled to be 0.04-0.15%;

[0023] P and S are inevitable impurity elements in pipeline steel. They are easy to segregate and form inclusions, which have an adverse effect on the mechanical properties of the steel plate. Their content should be reduced as much as possible. Therefore, the P content should be controlled to ≤0.015% and the S content should be controlled to ≤0.005%.

[0024] The present invention adopts ultra-low C content to ensure the weldability and high toughness of pipeline steel.

[0025] The V element in the present invention plays a key role in strengthening and resisting high-pressure hydrogen embrittlement of the pipeline steel. Its content is 0.04-0.15%. When V exceeds 0.04% in the steel, a large amount of nano-VC precipitation phase can be generated. However, if the V content is too high, more C content is required.

[0026] Any possible implementation as described above further provides an implementation, in step S2, the first temperature is 1200-1250° C., and the insulation time is 1-2 hours.

[0027] Any possible implementation as described above further provides an implementation, in which, in step S3, the second temperature is 1150-1000°C, and the controlled rolling reduction of the first stage rolling is not less than 60%; the third temperature is 900-800°C, and the controlled rolling reduction of the second stage rolling is not less than 50%.

[0028] Any possible implementation as described above further provides an implementation, in which in step S4, the fourth temperature is 550-670° C., and the insulation time is 0.5-1 hour.

[0029] Any possible implementation as described above further provides an implementation, in step S4, the cooling rate after hot rolling is controlled to be 10-50°C / s. If the cooling rate is too fast, hard phase structures such as Mao Island will be generated, while if the cooling rate is too slow, a large amount of pearlite will be generated.

[0030] On the other hand, the present invention also provides a high-pressure hydrogen pipeline steel, which is produced using the above method.

[0031] Any possible implementation as described above, further provides an implementation, in which the element compositions used are, by mass percentage, C: 0.02-0.04%, Si: 0.15-0.25%, Mn: 1.0-1.3%, Ni: 0.15-0.25%, Mo: 0.1-0.2%, Nb: 0.03-0.06%, Ti: 0.01-0.02%, V: 0.06-0.1%, P: ≤0.015%, S: ≤0.005%, and the remainder is Fe and other inevitable impurities.

[0032] As described above in any possible implementation, an implementation is further provided, wherein the matrix structure of the high-pressure hydrogen pipeline steel is a single-phase ferrite structure, or a mixed structure of ferrite and a small amount of pearlite.

[0033] On the other hand, the present invention also provides an application of the above-mentioned high-pressure resistant hydrogen pipeline steel, wherein the high-pressure resistant hydrogen pipeline steel is used as steel for transporting pipelines of high-pressure hydrogen.

[0034] The beneficial effects of the present invention are:

[0035] 1. The present invention generates nano-VC precipitation phase through post-rolling aging heat treatment to obtain single-phase ferrite or a mixed structure of ferrite and a small amount of pearlite. The strength and toughness of the new pipeline steel reach those of traditional X70 grade pipeline steel.

[0036] 2. The pipeline steel of the present invention has excellent resistance to high-pressure hydrogen embrittlement. After a slow tensile test in 10 MPa hydrogen, the elongation is greater than 20%, and the sensitivity to high-pressure hydrogen embrittlement is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Shown is the metallographic structure diagram of the high-pressure hydrogen pipeline steel in Example 1.

[0038] Figure 2 Shown is the metallographic structure diagram of the high-pressure hydrogen pipeline steel in Example 2.

[0039] Figure 3 Shown is the metallographic structure diagram of the high-pressure hydrogen pipeline steel in Example 3.

[0040] Figure 4 Shown is a schematic flow chart of a method for preparing high-pressure hydrogen pipeline steel according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The specific embodiments of the present invention will be described in detail below in conjunction with specific drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects.

[0042] The present invention provides a method for preparing a high pressure resistant hydrogen pipeline steel, such as Figure 4 As shown, including:

[0043] S1. Prepare, smelt and cast into billets according to the set element mass percentage; the elements include C, Si, Mn, Ni, Mo, Nb, Ti and V:

[0044] S2, heating the ingot to a first temperature and keeping the temperature for a certain period of time;

[0045] S3, performing thermomechanical controlled rolling on the ingot, performing a first stage rolling at a second temperature, controlling the rolling reduction; and then performing a second stage rolling at a third temperature, controlling the rolling reduction;

[0046] S4, cooling to the fourth temperature after hot rolling for heat preservation treatment, and then air cooling to room temperature to obtain high-pressure hydrogen pipeline steel;

[0047] The first temperature, the second temperature, the third temperature and the fourth temperature decrease in sequence.

[0048] In a specific embodiment, in step S1, the mass ratio of elements is: C: 0.02-0.05%, Si: 0.15-0.45%, Mn: 1.0-1.4%, Ni: 0.15-0.4%, Mo: 0.1-0.4%, Nb: 0.03-0.06%, Ti: 0.01-0.04%, V: 0.04-0.15%, P: ≤0.015%, S: ≤0.005%, and the balance is Fe.

[0049] In a specific embodiment, in step S2, the first temperature is 1200-1250° C., and the insulation time is 1-2 hours.

[0050] In a specific embodiment, in step S3, the second temperature is 1150-1000°C, and the controlled rolling reduction of the first rolling stage is not less than 60%; the third temperature is 900-800°C, and the controlled rolling reduction of the second rolling stage is not less than 50%.

[0051] In a specific embodiment, in step S4, the fourth temperature is 550-670° C., and the insulation time is 0.5-1 hour.

[0052] In a specific embodiment, in step S4, the cooling rate after hot rolling is controlled to be 10-50° C. / s.

[0053] The embodiment of the present invention provides a high-pressure hydrogen pipeline steel, which is prepared by using the above method.

[0054] In a specific embodiment, the element compositions used are C: 0.02-0.05%, Si: 0.15-0.45%, Mn: 1.0-1.4%, Ni: 0.15-0.4%, Mo: 0.1-0.4%, Nb: 0.03-0.06%, Ti: 0.01-0.04%, V: 0.04-0.15%, P: ≤0.015%, S: ≤0.005%, and the remainder is Fe and other inevitable impurities.

[0055] The matrix structure of the high-pressure hydrogen pipeline steel is a single-phase ferrite structure, or a mixed structure of ferrite and a small amount of pearlite.

[0056] Example 1

[0057] The chemical composition of the high-pressure hydrogen pipeline steel is as follows by mass percentage: C: 0.03, Si: 0.2%, Mn: 1.3%, Ni: 0.2%, Mo: 0.1%, Nb: 0.04%, Ti: 0.015%, V: 0.08%, P: ≤0.015%, S: ≤0.005%, and the balance is Fe and other inevitable impurities.

[0058] The preparation method of embodiment 1:

[0059] 1) Smelting and casting into billets according to the mass percentage of the elements;

[0060] 2) Heat the ingot to 1200°C and keep it at this temperature for 2 hours;

[0061] 3) The ingot is subjected to thermomechanical controlled rolling, the first stage of rolling is carried out in the temperature range of 1100-1000° C., the rolling reduction is controlled to be 60%, and then the second stage of rolling is carried out in the temperature range of 900-850° C., the rolling reduction is controlled to be 50%;

[0062] 4) After hot rolling, the cooling rate is controlled at 50°C / s, the steel is water-cooled to 620°C, the holding time is 0.5 hours, and then air-cooled to complete the preparation of X70 grade pipeline steel resistant to high pressure hydrogen.

[0063] Conventional and 10 MPa hydrogen environment slow tensile tests were performed on Example 1, and the measured mechanical property data are shown in Table 1. Figure 1 This is the metallographic structure of the pipeline steel in Example 1, which is a single-phase ferrite structure.

[0064] Table 1 shows the mechanical properties of slow stretching in different environments of Example 1

[0065]

[0066] * Impact specimen is half size: 5mm×10mm×55mm

[0067] Example 2

[0068] The chemical composition of the high-pressure hydrogen resistant X70 grade pipeline steel is as follows by mass percentage: C: 0.02, Si: 0.3%, Mn: 1.4%, Ni: 0.25%, Mo: 0.2%, Nb: 0.04%, Ti: 0.02%, V: 0.06%, P: ≤0.015%, S: ≤0.005%, and the balance is Fe and other inevitable impurities.

[0069] The preparation method of embodiment 2:

[0070] 1) Smelting and casting into billets according to the mass percentage of the elements;

[0071] 2) Heat the ingot to 1200°C and keep it at this temperature for 2 hours;

[0072] 3) The ingot is subjected to thermomechanical controlled rolling, the first stage of rolling is carried out in the temperature range of 1150-1050° C., the rolling reduction is controlled to be 60%, and then the second stage of rolling is carried out in the temperature range of 900-800° C., the rolling reduction is controlled to be 50%;

[0073] 4) After hot rolling, the cooling rate is controlled at 25°C / s, the steel is water-cooled to 550°C, the holding time is 1 hour, and then air-cooled to complete the preparation of X70 grade pipeline steel resistant to high pressure hydrogen.

[0074] Conventional and 10 MPa hydrogen environment slow tensile tests were performed on Example 2, and the measured mechanical property data are shown in Table 2. Figure 2 This is the metallographic structure of the pipeline steel of Example 2, which is ferrite and a very small amount of pearlite.

[0075] Table 2 shows the mechanical properties of slow stretching in different environments in Example 2

[0076]

[0077]

[0078] * Impact specimen is half size: 5mm×10mm×55mm

[0079] Example 3

[0080] The chemical composition of the high-pressure hydrogen pipeline steel is as follows by mass percentage: C: 0.05, Si: 0.15%, Mn: 1.2%, Ni: 0.2%, Mo: 0.2%, Nb: 0.06%, Ti: 0.02%, V: 0.15%, P: ≤0.015%, S: ≤0.005%, and the balance is Fe and other inevitable impurities.

[0081] The preparation method of embodiment 3:

[0082] 1) Smelting and casting into billets according to the mass percentage of the elements;

[0083] 2) Heat the ingot to 1200°C and keep it at this temperature for 2 hours;

[0084] 3) The ingot is subjected to thermomechanical controlled rolling, the first stage of rolling is carried out in the temperature range of 1100-1000° C., the rolling reduction is controlled to be 60%, and then the second stage of rolling is carried out in the temperature range of 900-800° C., the rolling reduction is controlled to be 50%;

[0085] 4) After hot rolling, the cooling rate is controlled at 15°C / s, the steel is water-cooled to 670°C, the holding time is 1 hour, and then air-cooled to complete the preparation of X70 grade pipeline steel resistant to high pressure hydrogen.

[0086] Conventional and 10 MPa hydrogen environment slow tensile tests were performed on Example 3, and the measured mechanical property data are shown in Table 3. Figure 3 This is the metallographic structure of the pipeline steel in Example 3, which is ferrite and a small amount of pearlite.

[0087] Table 3 shows the mechanical properties of slow stretching in different environments of Example 3

[0088]

[0089] * Impact specimen is half size: 5mm×10mm×55mm

[0090] From the performance comparison of Example 1, Example 2 and Example 3 under different test environments, it can be seen that according to the composition and preparation method provided by the present invention, the new pipeline steel meets the mechanical property requirements of X70 grade pipeline steel and has lower high-pressure hydrogen embrittlement sensitivity.

[0091] Although several embodiments of the present invention have been given herein, those skilled in the art should understand that the embodiments of the present invention may be modified without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as a limitation on the scope of the present invention.

Claims

1. A method for preparing high-pressure hydrogen pipeline steel, characterized in that: The method comprises: S1. Prepare, smelt and cast into billets according to the set element mass percentage; the elements include C, Si, Mn, Ni, Mo, Nb, Ti and V: S2, heating the ingot to a first temperature and keeping it at that temperature for a certain period of time; S3, performing thermomechanical controlled rolling on the ingot, performing a first stage rolling at a second temperature, controlling the rolling reduction; and then performing a second stage rolling at a third temperature, controlling the rolling reduction; S4, cooling to the fourth temperature after hot rolling for heat preservation treatment, and then air cooling to room temperature to obtain high-pressure hydrogen pipeline steel; The first temperature, the second temperature, the third temperature and the fourth temperature decrease in sequence.

2. The method for preparing high-pressure hydrogen pipeline steel according to claim 1, characterized in that: In step S1, the mass ratio of elements is: C: 0.02-0.05%, Si: 0.15-0.45%, Mn: 1.0-1.4%, Ni: 0.15-0.4%, Mo: 0.1-0.4%, Nb: 0.03-0.06%, Ti: 0.01-0.04%, V: 0.04-0.15%, P: ≤0.015%, S: ≤0.005%, and the balance is Fe.

3. The method for preparing high pressure hydrogen pipeline steel according to claim 1, characterized in that: In step S2, the first temperature is 1200-1250°C, and the insulation time is 1-2 hours.

4. The method for preparing high-pressure hydrogen pipeline steel according to claim 1, characterized in that: In step S3, the second temperature is 1150-1000°C, and the controlled rolling reduction of the first stage rolling is not less than 60%; the third temperature is 900-800°C, and the controlled rolling reduction of the second stage rolling is not less than 50%.

5. The method for preparing high-pressure hydrogen pipeline steel according to claim 1, characterized in that: In step S4, the fourth temperature is 550-670° C., and the insulation time is 0.5-1 hour.

6. The method for preparing high-pressure hydrogen pipeline steel according to claim 1, characterized in that: In step S4, the cooling rate after hot rolling is controlled to be 10 to 50°C / s.

7. A high-pressure hydrogen pipeline steel, characterized in that: Prepared by the method according to any one of claims 1 to 6.

8. The high pressure resistant hydrogen pipeline steel according to claim 7, characterized in that: The element compositions used are C: 0.02-0.05%, Si: 0.15-0.45%, Mn: 1.0-1.4%, Ni: 0.15-≤0.4%, Mo: 0.1-0.4%, Nb: 0.03-0.06%, Ti: 0.01-0.04%, V: 0.04-0.15%, P: ≤0.015%, S: ≤0.005%, and the remainder is Fe and other inevitable impurities.

9. The high pressure resistant hydrogen pipeline steel according to claim 7 or 8, characterized in that: The matrix structure of the high-pressure hydrogen pipeline steel is a single-phase ferrite structure, or a mixed structure of ferrite and a small amount of pearlite.

10. Use of the high pressure resistant hydrogen pipeline steel according to any one of claims 7 to 9, characterized in that: The high-pressure resistant hydrogen pipeline steel is used as steel for transporting pipelines of high-pressure hydrogen.

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