CN111876685A - High-toughness pipeline steel with yield strength of 555MPa and production method thereof - Google Patents
High-toughness pipeline steel with yield strength of 555MPa and production method thereof Download PDFInfo
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
Abstract
The invention relates to a high-toughness pipeline steel with yield strength of 555MPa and a production method thereof, wherein the pipeline steel comprises the following chemical components in percentage by mass: c: 0.04-0.08%, Si: 0.05-0.15%, Mn: 1.0-1.2%, S: 0.001-0.003%, P: less than or equal to 0.008 percent, Als: 0.02-0.05%, Nb: 0.05-0.07%, Ti: 0.015-0.025%, and the balance of Fe and inevitable impurities. During preparation, after heating and heat preservation are carried out on steel billets with corresponding components, the initial rolling temperature and the total accumulated reduction are controlled, 3-pass rough rolling is carried out, after the rough rolling, the intermediate billet is rapidly cooled, 4-pass finish rolling is carried out, the initial rolling temperature, the final rolling temperature and the total accumulated reduction are controlled, a steel plate with the thickness of 7-15 mm is obtained, and the quick cooling and the air cooling are combined to prepare the 555MPa grade high-toughness pipeline steel with the yield strength. The high-toughness pipeline steel which has high strength, high and low temperature toughness, low yield ratio and easy forming and has impact absorption work reaching 380J at-40 ℃ is prepared by integrally blending the components and the process.
Description
Technical Field
The invention belongs to the field of low-carbon low-alloy steel, and particularly relates to high-toughness pipeline steel with yield strength of 555MPa and a production method thereof.
Background
The low-carbon microalloy pipeline steel is applied to a plurality of pipeline construction projects due to high strength, good toughness and extensibility. Currently, as oil and gas exploitation places expand towards extremely cold northwest areas, the operating environment of pipeline steel tends to be complicated, and high-strength high-low-temperature-toughness pipeline steel is urgently needed. In order to improve the low-temperature toughness while ensuring the strength, a large amount of micro alloy elements such as niobium (Nb), vanadium (V), titanium (Ti) and the like, even noble alloy elements such as molybdenum (Mo) and nickel (Ni) are added when the 555 MPa-grade pipeline steel with yield strength is traditionally produced, so that the alloy cost is greatly improved. The cost is increased by adding the alloy elements, and the improvement of the performance of the pipeline steel is limited, so that the invention saves the precious alloy elements of molybdenum (Mo) and nickel (Ni) when designing the components, reduces the content of manganese (Mn), and provides a production method for manufacturing the 555MPa grade high-toughness pipeline steel with yield strength by optimizing the deformation process, performing water cooling at the intermediate blank temperature waiting stage, and improving the low-temperature toughness while ensuring the high strength.
Before the invention, a patent CN110284077A discloses a manufacturing method of thin-specification high-toughness pipeline steel, 0.2-0.3% of Si is added in the component design, red iron scale is easy to generate, and after rough rolling is finished, the intermediate blank is subjected to air cooling for temperature waiting, so that the temperature waiting time is long, and the production process period is long; the patent CN103276315B discloses a 900 MPa-grade ultrahigh-strength high-toughness pipeline steel plate and a manufacturing method thereof, precious alloy elements of molybdenum (Mo) and nickel (Ni) are added in the component design, the alloy cost is increased, the Si content is higher, the steel plate is easy to generate red iron scale, the highest low-temperature impact toughness at-20 ℃ in the embodiment is 253J, and the improvement on the low-temperature toughness is limited while the strength is greatly improved; patent CN103276314B discloses a low yield ratio and high toughness X80 pipeline steel plate and a manufacturing method thereof, which adopts a controlled rolling and controlled cooling process and carries out quenching and tempering treatment on the steel plate, thereby not only increasing the production difficulty, but also having limited improvement on low temperature toughness.
Disclosure of Invention
Aiming at various problems in the prior art, the invention provides 555MPa grade high-toughness pipeline steel with yield strength and a production method thereof, and the high-toughness pipeline steel which has high strength, high and low temperature toughness, low yield ratio and easy forming and has impact absorption power of 380J at minus 40 ℃ is prepared by integrally blending components and processes.
In order to achieve the purpose, the invention adopts the following technical scheme:
a high-toughness pipeline steel with yield strength of 555MPa comprises the following chemical components in percentage by mass: c: 0.04-0.08%, Si: 0.05-0.15%, Mn: 1.0-1.2%, S: 0.001-0.003%, P: less than or equal to 0.008 percent, Als: 0.02-0.05%, Nb: 0.05-0.07%, Ti: 0.015 to 0.025%, and the balance of Fe and inevitable impurities.
The high-toughness pipeline steel with the yield strength of 555MPa is fine acicular ferrite.
The high-toughness pipeline steel plate with the yield strength of 555MPa is 7-15 mm thick, and the main mechanical properties of the high-toughness pipeline steel plate meet the following requirements: the tensile strength is 670-710 MPa, the yield strength is 570-625 MPa, the yield ratio is 0.85-0.88, the elongation after fracture is 26.0-31.5%, and the impact absorption power at-40 ℃ is 320-380J.
The production method of the high-toughness pipeline steel with the yield strength of 555MPa comprises the following steps:
(1) heating a steel billet to 1200-1230 ℃, and preserving heat for 1.0-1.3 h, wherein the steel billet comprises the following chemical components in percentage by mass: c: 0.04-0.08%, Si: 0.05-0.15%, Mn: 1.0-1.2%, S: 0.001-0.003%, P: less than or equal to 0.008 percent, Als: 0.02-0.05%, Nb: 0.05-0.07%, Ti: 0.015-0.025%, and the balance of Fe and inevitable impurities;
(2) carrying out 3-pass rough rolling on the heated steel billet, wherein the initial rolling temperature is 1170-1200 ℃, and the total accumulated reduction rate is 60.5-64.5%, so as to obtain an intermediate billet;
(3) water cooling the intermediate billet to reduce the surface temperature of the billet to 940-965 ℃;
(4) carrying out 4-pass finish rolling on the intermediate blank, wherein the initial rolling temperature is 930-960 ℃, the total accumulated reduction rate is 62.0-80.3%, and the final rolling temperature is 810-850 ℃ to obtain a steel plate with the thickness of 7-15 mm;
(5) and (3) rapidly cooling the steel plate at a cooling speed of 100-130 ℃/s, wherein the final cooling temperature is 430-560 ℃, and then air-cooling to room temperature to obtain the high-toughness pipeline steel with the yield strength of 555 MPa.
In the step (1), the thickness of the steel billet is 100 mm.
In the step (2), 3 passes of rolling are carried out, and the 3 rd pass reduction rate is 45.1-47.8%.
In the step (3), the thickness of the intermediate blank is 35.5-39.5 mm, and the water cooling speed of the intermediate blank is 40-50 ℃/s.
In the step (5), the single-pass reduction rate is 16.7-38.0% after 4-pass rolling.
The invention carries out brand new design on the chemical components and the production process of the 555MPa grade high-toughness pipeline steel with yield strength, and has the following beneficial effects:
(1) in the component design, precious alloys of molybdenum (Mo) and nickel (Ni) are saved, the cost of adding 0.1 percent of molybdenum (Mo) alloy in the steel is about 200 yuan/ton, and the cost of adding 0.1 percent of nickel (Ni) alloy is about 100 yuan/ton, so that the production cost is greatly reduced compared with the traditional 555MPa grade pipeline steel production method;
(2) the design idea of low silicon (Si) components is adopted, so that the generation of red iron oxide scales on the surface of the steel plate is reduced, and the surface quality of the steel plate is good;
(3) compared with the traditional process for producing pipeline steel, the invention controls rolling, cools the steel plate by water when the intermediate billet is heated, increases cooling speed, reduces heating time, improves production efficiency and saves cost;
(4) the 555MPa grade high-toughness pipeline steel with yield strength has high strength, high and low temperature toughness and low yield ratio, is easy to form, and has impact absorption work reaching 380J at-40 ℃.
Drawings
FIG. 1 is a photograph of a metallographic structure of a steel plate for a pipeline having a thickness of 7.0mm and a yield strength of 555MPa grade prepared in example 1 of the present invention;
FIG. 2 is a scanning photograph of the impact fracture of a 7.0mm thick 555MPa grade yield strength pipeline steel plate prepared in example 1 of the present invention;
FIG. 3 is a scanning photograph of the impact fracture of a 9.0mm thick 555MPa grade yield strength pipeline steel plate prepared in example 2 of the present invention.
Detailed Description
The present invention is further illustrated by the following examples, but the scope of the present invention is not limited to the following examples.
Example 1
The high-toughness pipeline steel with the yield strength of 555MPa grade provided by the embodiment comprises the following chemical components in percentage by mass: c: 0.04%, Si: 0.05%, Mn: 1.0%, S: 0.003%, P: 0.008%, Als: 0.02%, Nb: 0.05%, Ti: 0.015% and the balance Fe and inevitable impurities.
A preparation method of a high-toughness pipeline steel with yield strength of 555MPa and thickness of 7.0mm comprises the following process steps:
(1) heating a steel billet with the thickness of 100mm to 1230 ℃, and preserving heat for 1.0h, wherein the steel billet comprises the following chemical components in percentage by mass: c: 0.04%, Si: 0.05%, Mn: 1.0%, S: 0.003%, P: 0.008%, Als: 0.02%, Nb: 0.05%, Ti: 0.015% and the balance of Fe and inevitable impurities;
(2) carrying out 3-pass rough rolling on the heated billet, wherein the initial rolling temperature is 1200 ℃, the reduction pass distribution is 100mm → 80mm → 68mm → 35.5mm, the total cumulative reduction rate is 64.5%, and the 3 rd-pass reduction rate is 47.8%, so as to obtain an intermediate billet with the thickness of 35.5 mm;
(3) cooling the intermediate blank to 965 ℃ in a water cooling mode at a cooling speed of 40 ℃/s;
(4) performing 4-pass finish rolling on the intermediate blank, wherein the initial rolling temperature is 960 ℃, the reduction pass distribution is 35.5mm → 22mm → 16mm → 10mm → 7mm, the total cumulative reduction rate is 80.3%, and the final rolling temperature is 850 ℃ to obtain a steel plate with the thickness of 7.0mm
(5) And rapidly cooling the steel plate to 480 ℃ at the speed of 130 ℃/s, and then air-cooling to room temperature to obtain the high-toughness pipeline steel with the yield strength of 555 MPa.
The metallographic structure photograph of the quarter position of the thickness section of the prepared pipeline steel plate with the thickness of 7.0mm and the yield strength of 555MPa grade is shown in figure 1, the steel structure is fine acicular ferrite, after the steel plate is subjected to an impact test, the scanning photograph of the impact fracture of the pipeline steel plate is shown in figure 2, and the visible fracture mode is dimple fracture; the tensile strength is 710MPa, the yield strength is 610MPa, the yield ratio is 0.86, the elongation after fracture is 31.5 percent, and the impact absorption work at minus 40 ℃ is 380J.
Example 2
The high-toughness pipeline steel with the yield strength of 555MPa grade provided by the embodiment comprises the following chemical components in percentage by mass: c: 0.05%, Si: 0.055%, Mn: 1.05%, S: 0.002%, P: 0.007%, Als: 0.021%, Nb: 0.055%, Ti: 0.015% and the balance Fe and inevitable impurities.
A preparation method of high-toughness pipeline steel with the yield strength of 555MPa and the thickness of 9.0mm comprises the following process steps:
(1) heating a steel billet with the thickness of 100mm to 1220 ℃, and preserving heat for 1.1h, wherein the steel billet comprises the following chemical components in percentage by mass: c: 0.05%, Si: 0.055%, Mn: 1.05%, S: 0.002%, P: 0.007%, Als: 0.021%, Nb: 0.055%, Ti: 0.015% and the balance of Fe and inevitable impurities;
(2) carrying out 3-pass rough rolling on the heated billet, wherein the initial rolling temperature is 1190 ℃, the reduction pass distribution is 100mm → 81mm → 68mm → 36mm, the total cumulative reduction rate is 64.0%, and the 3 rd-pass reduction rate is 47.1%, so as to obtain an intermediate billet with the thickness of 36 mm;
(3) cooling the intermediate blank to 965 ℃ in a water cooling mode at a cooling speed of 42 ℃/s;
(4) performing 4-pass finish rolling on the intermediate blank, wherein the initial rolling temperature is 960 ℃, the reduction pass distribution is 36mm → 25mm → 18.5mm → 12mm → 9mm, the total cumulative reduction rate is 75.0%, and the final rolling temperature is 840 ℃ to obtain a steel plate with the thickness of 9.0 mm;
(5) and rapidly cooling the steel plate to 530 ℃ at the speed of 115 ℃/s, and then air-cooling to room temperature to obtain the high-toughness pipeline steel with the yield strength of 555 MPa.
The scanning picture of the impact fracture of the prepared 9.0mm thick pipeline steel plate with the yield strength of 555MPa grade is shown in figure 3, and the steel structure is fine acicular ferrite; the tensile strength is 690MPa, the yield strength is 595MPa, the yield ratio is 0.86, the elongation after fracture is 30.0 percent, and the impact absorption work at minus 40 ℃ is 360J.
Example 3
The high-toughness pipeline steel with the yield strength of 555MPa grade provided by the embodiment comprises the following chemical components in percentage by mass: c: 0.06%, Si: 0.08%, Mn: 1.1%, S: 0.002%, P: 0.007%, Als: 0.028%, Nb: 0.06%, Ti: 0.018%, and the balance of Fe and inevitable impurities.
A preparation method of thick-gauge high-toughness X80 pipeline steel with the thickness of 12.0mm comprises the following process steps:
(1) heating a steel billet with the thickness of 100mm to 1220 ℃, and preserving heat for 1.2h, wherein the steel billet comprises the following chemical components in percentage by mass: c: 0.06%, Si: 0.08%, Mn: 1.1%, S: 0.002%, P: 0.007%, Als: 0.028%, Nb: 0.06%, Ti: 0.018%, the balance being Fe and unavoidable impurities;
(2) carrying out 3-pass rough rolling on the heated billet, wherein the initial rolling temperature is 1195 ℃, the reduction pass distribution is 100mm → 82.5mm → 69mm → 37mm, the total cumulative reduction rate is 63.0%, and the 3 rd-pass reduction rate is 46.4%, so as to obtain an intermediate billet with the thickness of 37 mm;
(3) cooling the intermediate blank to 950 ℃ in a water cooling mode at a cooling speed of 45 ℃/s;
(4) carrying out 4-pass finish rolling on the intermediate blank, wherein the initial rolling temperature is 940 ℃, the reduction pass distribution is 37mm → 26mm → 19mm → 15mm → 12mm, the total accumulated reduction rate is 67.6%, and the final rolling temperature is 830 ℃, so as to obtain a steel plate with the thickness of 12.0 mm;
(5) and rapidly cooling the steel plate to 480 ℃ at the speed of 120 ℃/s, and then air-cooling to room temperature to obtain the high-toughness pipeline steel with the yield strength of 555 MPa.
The 555MPa grade high-toughness pipeline steel with the yield strength of 12.0mm has a fine acicular ferrite structure, the fracture morphology of a scanned impact sample of the steel plate is visible after an impact test, and the fracture mode is dimple fracture; the tensile strength is 697MPa, the yield strength is 590MPa, the yield ratio is 0.85, the elongation after fracture is 28.3%, and the impact absorption work at-40 ℃ is 335J.
Example 4
The high-toughness pipeline steel with the yield strength of 555MPa grade provided by the embodiment comprises the following chemical components in percentage by mass: c: 0.06%, Si: 0.09%, Mn: 1.15%, S: 0.001%, P: 0.007%, Als: 0.035%, Nb: 0.063%, Ti: 0.02%, and the balance of Fe and inevitable impurities.
A preparation method of high-toughness pipeline steel with yield strength of 555MPa and thickness of 14.0mm comprises the following process steps:
(1) heating a steel billet with the thickness of 100mm to 1210 ℃, and preserving heat for 1.2h, wherein the steel billet comprises the following chemical components in percentage by mass: c: 0.06%, Si: 0.09%, Mn: 1.15%, S: 0.001%, P: 0.007%, Als: 0.035%, Nb: 0.063%, Ti: 0.02%, the balance being Fe and unavoidable impurities;
(2) carrying out 3-pass rough rolling on the heated billet, wherein the initial rolling temperature is 1180 ℃, the reduction pass distribution is 100mm → 79mm → 70mm → 38mm, the total cumulative reduction rate is 62.0%, and the 3 rd-pass reduction rate is 45.7%, so as to obtain an intermediate billet with the thickness of 38 mm;
(3) cooling the intermediate blank to 945 ℃ in a water cooling mode at a cooling speed of 48 ℃/s;
(4) carrying out 4-pass finish rolling on the intermediate blank, wherein the initial rolling temperature is 940 ℃, the reduction pass distribution is 38mm → 27.5mm → 21mm → 17mm → 14mm, the total cumulative reduction rate is 63.2%, and the final rolling temperature is 820 ℃ to obtain a steel plate with the thickness of 14.0 mm;
(5) and rapidly cooling the steel plate to 430 ℃ at the speed of 125 ℃/s, and then air-cooling to room temperature to obtain the high-toughness pipeline steel with the yield strength of 555 MPa.
The 555MPa grade high-toughness pipeline steel with the yield strength of 14.0mm has a fine acicular ferrite structure, the fracture morphology of a scanned impact sample of the steel plate is visible after an impact test, and the fracture mode is dimple fracture; the tensile strength is 707MPa, the yield strength is 625MPa, the yield ratio is 0.88, the elongation after fracture is 26.0 percent, and the impact absorption work at-40 ℃ is 320J.
Example 5
The high-toughness pipeline steel with the yield strength of 555MPa grade provided by the embodiment comprises the following chemical components in percentage by mass: c: 0.08%, Si: 0.15%, Mn: 1.2%, S: 0.003%, P: 0.008%, Als: 0.05%, Nb: 0.07%, Ti: 0.025%, and the balance of Fe and inevitable impurities.
A preparation method of thick-gauge high-toughness X80 pipeline steel with the thickness of 15.0mm comprises the following process steps:
(1) heating a steel billet with the thickness of 100mm to 1200 ℃, and preserving heat for 1.3h, wherein the steel billet comprises the following chemical components in percentage by mass: c: 0.08%, Si: 0.15%, Mn: 1.2%, S: 0.003%, P: 0.008%, Als: 0.05%, Nb: 0.07%, Ti: 0.025%, and the balance of Fe and inevitable impurities;
(2) carrying out 3-pass rough rolling on the heated billet, wherein the initial rolling temperature is 1170 ℃, the reduction pass distribution is 100mm → 83mm → 72mm → 39.5mm, the total cumulative reduction rate is 60.5%, the 3 rd-pass reduction rate is 45.1%, and an intermediate billet with the thickness of 39.5mm is obtained;
(3) cooling the intermediate blank to 940 ℃ in a water cooling mode, wherein the cooling speed is 50 ℃/s;
(4) carrying out 4-pass finish rolling on the intermediate blank, wherein the initial rolling temperature is 930 ℃, the reduction pass distribution is 39.5mm → 28mm → 22mm → 18mm → 15mm, the total cumulative reduction rate is 62.0%, and the final rolling temperature is 810 ℃ to obtain a steel plate with the thickness of 15.0 mm;
(5) and rapidly cooling the steel plate to 560 ℃ at the speed of 100 ℃/s, and then air-cooling to room temperature to obtain the high-toughness pipeline steel with the yield strength of 555 MPa.
The yield strength 555MPa grade high-toughness pipeline steel with the thickness of 15.0mm is fine acicular ferrite; the tensile strength is 670MPa, the yield strength is 570MPa, the yield ratio is 0.85, the elongation after fracture is 27.3 percent, and the impact absorption work at minus 40 ℃ is 325J.
Claims (8)
1. A high-toughness pipeline steel with yield strength of 555MPa grade is characterized by comprising the following chemical components in percentage by mass: c: 0.04-0.08%, Si: 0.05-0.15%, Mn: 1.0-1.2%, S: 0.001-0.003%, P: less than or equal to 0.008 percent, Als: 0.02-0.05%, Nb: 0.05-0.07%, Ti: 0.015 to 0.025%, and the balance of Fe and inevitable impurities.
2. The high-toughness pipeline steel with yield strength of 555MPa according to claim 1, wherein the high-toughness pipeline steel with yield strength of 555MPa is acicular ferrite.
3. The high-toughness pipeline steel with the yield strength of 555MPa as claimed in claim 1, wherein the thickness of the high-toughness pipeline steel plate with the yield strength of 555MPa is 7-15 mm, and the main mechanical properties of the high-toughness pipeline steel plate meet the following requirements: the tensile strength is 670-710 MPa, the yield strength is 570-625 MPa, the yield ratio is 0.85-0.88, the elongation after fracture is 26.0-31.5%, and the impact absorption power at-40 ℃ is 320-380J.
4. The production method of the high-toughness pipeline steel with the yield strength of 555MPa grade as recited in claim 1, is characterized by comprising the following steps:
(1) heating a steel billet to 1200-1230 ℃, and preserving heat for 1.0-1.3 h, wherein the steel billet comprises the following chemical components in percentage by mass: c: 0.04-0.08%, Si: 0.05-0.15%, Mn: 1.0-1.2%, S: 0.001-0.003%, P: less than or equal to 0.008 percent, Als: 0.02-0.05%, Nb: 0.05-0.07%, Ti: 0.015-0.025%, and the balance of Fe and inevitable impurities;
(2) carrying out 3-pass rough rolling on the heated steel billet, wherein the initial rolling temperature is 1170-1200 ℃, and the total accumulated reduction rate is 60.5-64.5%, so as to obtain an intermediate billet;
(3) water cooling the intermediate billet to reduce the surface temperature of the billet to 940-965 ℃;
(4) carrying out 4-pass finish rolling on the intermediate blank, wherein the initial rolling temperature is 930-960 ℃, the total accumulated reduction rate is 62.0-80.3%, and the final rolling temperature is 810-850 ℃ to obtain a steel plate with the thickness of 7-15 mm;
(5) and (3) rapidly cooling the steel plate at a cooling speed of 100-130 ℃/s, wherein the final cooling temperature is 430-560 ℃, and then air-cooling to room temperature to obtain the high-toughness pipeline steel with the yield strength of 555 MPa.
5. The method for producing the high-toughness pipeline steel with the yield strength of 555MPa according to claim 4, wherein in the step (1), the thickness of the steel billet is 100 mm.
6. The production method of the high-toughness pipeline steel with the yield strength of 555MPa according to claim 4, wherein in the step (2), after 3-pass rolling, the reduction rate of the 3 rd pass is 45.1-47.8%.
7. The production method of the high-toughness pipeline steel with the yield strength of 555MPa according to claim 4, wherein in the step (3), the thickness of the intermediate blank is 35.5-39.5 mm, and the water cooling speed of the intermediate blank is 40-50 ℃/s.
8. The production method of the high-toughness pipeline steel with the yield strength of 555MPa according to claim 4, wherein in the step (5), after 4-pass rolling, the single-pass reduction rate is 16.7-38.0%.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101845596A (en) * | 2009-03-24 | 2010-09-29 | 宝山钢铁股份有限公司 | Wide thick plate for X80 pipe line steel and manufacturing method thereof |
| CN102230128A (en) * | 2011-06-02 | 2011-11-02 | 首钢总公司 | Low-cost X70 pipeline steel plate and preparation method thereof |
| WO2019219031A1 (en) * | 2018-05-16 | 2019-11-21 | 宝山钢铁股份有限公司 | High-strength double-sided stainless steel composite board and manufacturing method therefor |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101845596A (en) * | 2009-03-24 | 2010-09-29 | 宝山钢铁股份有限公司 | Wide thick plate for X80 pipe line steel and manufacturing method thereof |
| CN102230128A (en) * | 2011-06-02 | 2011-11-02 | 首钢总公司 | Low-cost X70 pipeline steel plate and preparation method thereof |
| WO2019219031A1 (en) * | 2018-05-16 | 2019-11-21 | 宝山钢铁股份有限公司 | High-strength double-sided stainless steel composite board and manufacturing method therefor |
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