RU2793945C1 - Pipeline steel with both hic resistance and high deformation resistance and method for its manufacturing - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: pipeline steel used for the transportation of oil and natural gas. Pipeline steel has the following composition: C: 0.015–0.039%, Si: 0.15–0.35%, Mn: 1.6–1.9%, S: ≤ 0.002%, P: ≤ 0.012%, Al: 0.02–0.045%, Cr: 0.15–0.35%, 0.05≤ Nb + V + Ti≤ 0.1%, Nb, V and Ti are not equal to 0, Ni: 0.15–0.50%, Cu: 0.01–0.25%, Ca: ≤ 0.002%, N: ≤ 0.0046%, Mo: 0.01–0.20%, the rest is Fe and unavoidable impurities. The transverse yield strength is Rt0.5 490-550 MPa, the transverse tensile strength Rm ≥ 710 MPa, transverse ratio of yield strength to tensile strength Rt0.5/Rm ≤ 0.78, Charpy impact strength at -20°C greater than or equal to 350 J, drop shear area at -20°C is SA% ≥ 90%, longitudinal yield strength 460-530 MPa, longitudinal tensile strength greater than or equal to 690 MPa, longitudinal uniform elongation Uel ≥ 11%, the longitudinal ratio of yield strength to tensile strength is less than or equal to 0.77, and the longitudinal stress ratio is Rt1.5/Rt0.5≥1.18, Rt2.0/Rt1.0≥1.

EFFECT: high resistance of pipeline steel to hydrogen cracking and deformation resistance.

4 cl, 2 dwg, 1 tbl

Description

Technical field

The present invention relates to the field of iron-based alloys, in particular to pipeline steel.

Prerequisites for the creation of the invention

Pipeline transport is the most economical and reasonable way to transport oil and natural gas. The long transfer pipeline not only needs to pass through zones of varying temperatures, but also needs to pass through zones of formation movement caused by natural disasters such as tundra earthquakes, mudflows and landslides. Therefore, in addition to meeting the requirements of high strength and high toughness, the pipeline also needs to have a relatively high deformation resistance in order to adapt to the geological conditions during pumping.

Large deformation resistant pipeline steel is one of the most difficult areas of research in the field of pipeline steel development, in which pipeline steel is required to have a higher resistance to compression and tension. A large number of studies have shown that in addition to the main performance parameters of strength and ductility, such as yield strength, tensile strength and elongation at break, the main indicators that can measure its resistance to large deformation are "elongation at uniform plastic strain Ue ≥ 10%, yield strength ratio Rt0.5 / Rm ≤ 0.80”, etc.

For the requirement of "large deformation resistance", pipeline steels described in patent documents such as CN2009100760066.8, CN201210327206, and CN2009100760066.8 propose to obtain a ferrite + bainite two-phase structure by weakening and other methods, which have good characteristics of large deformation resistance. However, since the structure is a two-phase structure, see FIG. 2. In addition, the two-phase structure has an obvious stripe along the rolling direction, so the HIC resistance is not ideal. The two-phase structure easily accumulates hydrogen on the surface, and the banded structure can also cause hydrogen accumulation. For pipeline steel with a two-phase ferrite + bainite structure, HIC resistance is tested in accordance with the relevant NACE standards. The steel sheet has many HIC cracks in different thickness directions, and the HIC resistance is not ideal.

Detailed description of the invention

In view of the aforementioned technical field, the present invention provides a pipeline steel having both HIC resistance and high deformation resistance, and a production method thereof, which can adapt to product development of X80 grade pipeline steel and below. Pipeline steel not only has the characteristics of large deformation resistance such as low yield strength to tensile strength ratio, high uniform elongation and high stress ratio, but also has good HIC resistance.

The technical scheme used in the present invention to solve the above problems is as follows: a pipeline steel having both HIC resistance and high deformation resistance, which is characterized in that the alloy composition used is C: 0.015 - 0.039%, Si: 0 .15 - 0.35%, Mn: 1.6 - 1.9%, S: ≤ 0.002%, P: ≤ 0.012%, Al: 0.02 - 0.045%, Cr: 0.15 - 0.35% , 0.05 ≤ Nb + V + Ti ≤ 0.1%, Nb, V and Ti are not equal to 0, Ni: 0.15 - 0.50%, Cu: 0.01 - 0.25%, Ca: ≤ 0.002%, N: ≤ 0.0046%, Mo: 0.01 - 0.20%, and the balance is Fe and unavoidable impurity elements.

The Nb content is determined according to the content of C and niobium carbide, and the Ti content is determined according to the Ti/N stoichiometric ratio of 3.42.

In addition, the product is a bainite single-phase structure, and the grain size of bainite belongs to grades 11.5 to 12.

Transverse yield strength of the product according to the present invention Rt0.5: 490 - 550 MPa, transverse tensile strength Rm: ≥ 710 MPa, transverse yield strength to tensile strength ratio Rt0.5 / Rm ≤ 0.78, at -20 ℃ impact strength Charpy ≥ 350J, at -20℃ drop shear area SA% ≥ 90%; longitudinal yield strength 460 - 530 MPa; longitudinal tensile strength greater than or equal to 690 MPa, longitudinal uniform elongation Uel ≥ 11%, longitudinal ratio of yield strength to tensile strength less than or equal to 0.77; longitudinal stress factor Rt1.5/Rt0.5≥1.18, Rt2.0/Rt1.0≥1.1; and HIC resistance of the product: after soaking in NACE TM0284-2004 A solution for 96 hours, Crack Length %: 0, Crack Width %: 0, and Crack Sensitivity %: 0.

The structural basis for the chemical composition of the pipeline steel according to the present invention is as follows:

C: It is the most economical and basic reinforcing element in steel. The strength of steel can be greatly increased by solid solution and precipitates, but this will have a negative effect on the toughness, ductility and welding characteristics of the steel. Thus, the development trend of pipeline steel is to constantly reduce the content of C. Considering the characteristics of steel structure resistant to large deformations, in order to ensure that a specific bainitic structure is obtained, it is necessary to control C within an appropriate range. In the present invention, the C content is controlled at ≤ 0.039%, preferably 0.015-0.039%.

Si: is a deoxidizing element in steel, which enhances the strength of steel in the form of solid solution hardening and contributes to the corrosion resistance of steel. When the Si content is low, the deoxidation effect is weak, and when the Si content is high, the toughness will be lowered. The content of Si in accordance with the present invention is controlled at the level of 0.15 - 0.35%.

Mn: Strengthening of steel by solid solution hardening is the most important element in pipeline steel to compensate for the loss of strength caused by the reduction of C content. Mn is also an element for expanding the γ phase zone, reducing the γ→α phase transformation temperature of steel. Mn is useful for producing fine phase transformation products, increasing the toughness of the steel, and lowering the brittle-ductile transition temperature. Mn is also an element to improve the hardenability of steel. The content of Mn in the present invention is designed to be in the range of 1.6-1.9%.

Al: mainly for nitrogen fixation and deoxidation. AlN formed by combining Al and N can effectively fine grain, but too high content will damage the toughness of the steel and deteriorate the hot workability. Therefore, in the present invention, its content (Alt) is controlled in the range of 0.02 - 0.045%.

Cr: This is a ferrite forming element. At the same time, Cr can also improve the hardenability of steel. In the present invention, Cr is controlled at the level of 0.15 - 0.35%.

Nb: This is an element with a clear effect on grain refinement. The γ→α phase transformation of steel can be slowed down due to the resistance of the Nb solution. During the hot rolling process, Nb(C, n) precipitation caused by deformation can prevent the recovery and recrystallization of austenite. After rapid cooling, the deformed austenite rolled in the non-recrystallized zone forms fine phase transformation products during the phase transformation to improve the strength and toughness of the steel. In the present invention, the content of Nb is determined through the content of C, and the content of Nb and C is determined in accordance with the ratio of 1:1.

V: It has high dispersion strengthening and low grain refinement. When Nb, V and Ti are used in combination, V mainly plays a role in precipitation strengthening.

Ti: This is a strong solid N-element. The stoichiometric ratio Ti/N is 3.42. Using approximately 0.02% Ti can fix N in the steel below 60 ppm, and TiN precipitates can form during continuous casting of the billet. These fine precipitates can effectively prevent the growth of austenite grains during the heating of the billet and improve the solid state solubility of Nb in austenite. At the same time, it can improve the toughness of the welding heat-affected zone, which is an indispensable element in pipeline steel.

Mo: It can suppress the formation of ferrite during the γ→α phase transformation. It plays an important role in controlling phase transformation and improving the hardenability of the steel. In the present invention, Mo is controlled in the range of 0.01 - 0.20%.

S.P: It is an unavoidable impurity element in pipeline steel, which easily forms segregation, inclusions and other defects, which will adversely affect the toughness and hot workability of the steel sheet, and its content should be reduced as much as possible. The addition of an appropriate amount of Ca can convert the long-band sulphide inclusion in pipeline steel into a spherical CaS inclusion and significantly reduce the segregation of sulfur at the grain boundary. Ca is very useful for reducing the brittleness of the pipeline steel and improving the resistance of the pipeline steel to hot cracking during casting, but adding too much calcium will increase the inclusions in the pipeline steel, which will adversely affect the improvement of toughness. In the present invention, P ≤ 0.012%, S ≤ 0.002%, and Ca ≤ 0.002% are controlled so that the pipeline steel can obtain better toughness.

Cu, Ni：Steel strength can be improved by solid solution strengthening. On the one hand, the addition of Ni can improve the toughness of the steel and improve the heat brittleness easily caused by Cu in the steel. On the other hand, adding Ni can improve hardenability. In the present invention, Cu is controlled at the level of 0.01 - 0.25%; Ni is controlled at the level of 0.15 - 0.50%.

N: It is an impurity element harmful to toughness. To obtain excellent low-temperature toughness in the present invention, its content in steel is controlled to be ≤ 0.0046%.

The process for producing pipeline steel having both HIC resistance and high deformation resistance in the present application is as follows: first, molten steel is smelted according to the chemical composition plan; casting a continuous casting blank with a chemical composition corresponding to the chemical composition of the completed steel sheet; heating the continuous casting billet to 1120 - 1160 ℃ for 3 - 4 hours; and then unloaded from the furnace; after descaling with high pressure water, two-stage rolling is performed: the first stage is rolling in the recrystallization zone, and the initial rolling temperature is 1110 - 1150℃. After multi-pass rolling, the final temperature of rolling is kept at 1030 - 1080 ℃, and the deformation rate during rolling of two passes of rough rolling is controlled at ≥ 19%; the second rolling step is performed outside the recrystallization zone. The initial rolling temperature is 830-900℃, the final rolling temperature is controlled at 750-840℃, and the accumulated strain rate of the second stage rolling is ≥ 70%; after rolling, in accordance with the change in the austenitic microstructure, the steel sheet is sent to the cooling system through a roller table 45 m–95 m long with a transfer speed v = a * h, where H is the thickness of the steel sheet in mm, a = 0.05–0, 08 m/(s*mm).

In the cooling system, the workpiece is directly quenched, after direct quenching, air-cooled to Ar ₃ temperature, and then rapidly cooled. The cooling end temperature is controlled below 280℃, temperature straightening is performed, and finally air-cooled to room temperature, so as to obtain an X80 pipeline steel sheet having both HIC resistance and high deformation resistance.

The transfer rate of the roller table blank after rolling must take into account the movement of dislocations of the microstructure of the steel sheet after the austenite is sufficiently deformed to obtain a microstructure with a different dislocation density at different grain positions to provide growth conditions for obtaining a very fine bainitic structure.

Compared with the prior art, the present invention has the advantage that, according to the principle of HIC resistance and hydrogen trap theory, it is preferable to have a relatively uniform and uniform structure in order to achieve good HIC resistance performance. Although, according to the principle of high deformation resistance, the structure must have excellent co-deformability when deformed in order to have excellent large deformation resistance ability. This is confirmed by research, some low-carbon bainites have the ability to combine these two properties. According to the principle of deformation, the bainite must be very small, so as to have a good effect of joint deformation between grains in the deformation process, in order to obtain excellent large deformation resistance. In order to obtain this very fine bainite, it is necessary to develop a composition and process. The pipeline steel developed in accordance with the present invention has a uniform microstructure of very fine bainite, and the grain size of the microstructure reaches more than 11.5. Compared with the two-phase structure, H is not easy to aggregate, so it has good HIC resistance.

Description of attached graphics

In FIG. 1 is an organizational chart of an X80 pipe steel sheet with HIC and high deformation resistance in an embodiment of the invention;

In FIG. 2 shows the near-surface microstructure of an X80 pipeline steel produced by conventional relaxation air cooling.

Detailed description of embodiments

The present invention is described in more detail below in conjunction with the embodiments shown in the accompanying drawings. The embodiments described below with reference to the appended embodiments are illustrative and are intended to illustrate the present invention and should not be construed as limiting the present invention.

In the following embodiments, X80 steel grade pipeline steel is used as an example. The productivity and production complexity of steel grades lower than X80 steel grade, such as X70 and X60, is lower than that of X80, so they are not listed separately in this application.

Embodiment 1

A continuous casting billet with a thickness of not more than 370 mm is produced by continuous casting of molten steel corresponding to the chemical composition of the prepared pipeline steel sheet through a continuous casting machine. The chemical composition of the obtained continuous casting billet is: C: 0.015%, Si: 0.28%, Mn: 1.6%, S ≤ 0.002%, P ≤ 0.012%, Al: 0.03%, Cr: 0.35% , Nb + V + Ti: 0.06%, Ni: 0.50%, Cu: 0.15%, Ca: ≤ 0.002%, N: ≤ 0.0046%, Mo: 0.13%. The rest is Fe and unavoidable impurity elements.

The continuous casting billet is heated to 1150℃ for 3.5 hours, discharged from the furnace, descaled with 20MPa high pressure water, and then rolled in two stages: The first stage is recrystallization zone rolling, the initial rolling temperature is 1150℃ , and rolling is carried out in seven passes, in which the strain rate of two passes is ≥ 19%. The end temperature of rolling is 1050℃, and the thickness of the intermediate workpiece obtained after rolling in the recrystallization zone is 90mm; the second rolling step is performed outside the recrystallization zone. The starting temperature of rolling is 850℃, the end temperature of rolling is 810℃, the total deformation rate of rolling outside the recrystallization zone is ≥ 70%, and the thickness of the finished pipeline steel sheet is 22mm; after rolling, the steel sheet is sent to the cooling system through a 60 m long roller table with a transfer speed of 1.1 m/s. First, it is directly quenched in water, then air-cooled to Ar ₃ temperature after water discharge, then quickly cooled by ACC, the cooling end temperature is 250℃, and finally air-cooled to room temperature. The microstructure of the obtained pipeline steel is a very fine bainite with a grain size of 11.5. The morphology of the microstructure in the thickness direction is shown in FIG. 1. Compared with X80 pipeline steel, in the ferrite + bainite two-phase structure obtained by conventional relaxation air cooling, as shown in FIG. 2, the microstructure is more uniform and the bainite grain is finer. After testing, the strength and ductility indicators are as follows: transverse yield strength Rt0.5: 540 MPa; tensile strength Rm: 740 MPa, cross ratio of yield strength to tensile strength Rt0.5/Rm=0.76; longitudinal yield strength 510MPa, at -20℃ Charpy impact strength = 450J, SA% (-20℃) = 90%; longitudinal tensile strength Rm: 730 MPa, longitudinal uniform elongation Uel = 11%; the longitudinal ratio of yield strength to tensile strength is 0.70; longitudinal Rt1.5/Rt0.5 = 1.25, Rt2.0/Rt1.0 = 1.16. The HIC resistance test results are shown in Table 1.

Embodiment 2

A continuous casting billet with a thickness of not more than 370 mm is produced by continuous casting of molten steel corresponding to the chemical composition of the prepared pipeline steel sheet through a continuous casting machine. The chemical composition of the obtained continuous casting billet is: C: 0.03%, Si: 0.30%, Mn: 1.6%, S≤ 0.002%, P ≤ 0.012%, Al: 0.03%, Cr: 0, 25%, Nb + V + Ti: 0.06%, Ni: 0.25%, Cu: 0.15%, Ca: ≤ 0.002%, N: ≤ 0.0046%, Mo: 0.13%. The rest is Fe and unavoidable impurity elements.

The continuous casting billet is heated to 1150°C for 3.5 hours, unloaded from the furnace, descaled with water at a high pressure of 20 MPa, and then rolled in two stages: The first stage is rolling in the recrystallization zone, the initial rolling temperature is 1150 °C, and rolling is carried out in seven passes, in which the strain rate of two passes is ≥ 19%. The final rolling temperature is 1050 °C, and the thickness of the intermediate billet obtained after rolling in the recrystallization zone is 90 mm; the second rolling step is performed outside the recrystallization zone. The starting temperature of rolling is 850°C, the end temperature of rolling is 810°C, the total deformation rate of rolling outside the recrystallization zone is ≥ 70%, and the thickness of the finished pipeline steel sheet is 22mm; after rolling, the steel sheet is sent to the cooling system through a 60 m long roller table with a transfer speed of 1.1 m/s. First, it is directly quenched in water, then air-cooled to the Ar ₃ temperature after water discharge, then rapidly cooled by ACC, the final cooling temperature is 250 °C, and finally air-cooled to room temperature. The microstructure of the obtained pipeline steel is a very fine bainite with a grain size of 11.5. The morphology of the microstructure in the thickness direction is shown in FIG. 1. Compared with X80 pipeline steel, in the ferrite + bainite two-phase structure obtained by conventional relaxation air cooling, as shown in FIG. 2, the microstructure is more uniform and the bainite grain is finer. After testing, the strength and ductility indicators are as follows: transverse yield strength Rt0.5: 535 MPa; tensile strength Rm: 735 MPa, cross ratio of yield strength to tensile strength Rt0.5/Rm=0.76; longitudinal yield strength 500 MPa, at -20 °C Charpy impact strength = 450 J, SA% (-20 °C) = 90%; longitudinal tensile strength Rm: 730 MPa, longitudinal uniform elongation Uel = 12%; the longitudinal ratio of yield strength to tensile strength is 0.68; longitudinal Rt1.5/Rt0.5 = 1.27, Rt2.0/Rt1.0 = 1.17, HIC test results are shown in Table 1.

Embodiment 3

A continuous casting billet with a thickness of not more than 370 mm is produced by continuous casting of molten steel corresponding to the chemical composition of the prepared pipeline steel sheet through a continuous casting machine. The chemical composition of the obtained continuous casting billet is: C: 0.033%, Si: 0.25%, Mn: 1.8%, S≤0.002%, P≤0.012%, Al: 0.03%, Cr: 0.25% , Nb+V+Ti: 0.08%, Ni: 0.3%, Cu: 0.12%, Ca: ≤0.002%, N: ≤0.0046%, Mo: 0.20%. The rest is Fe and unavoidable impurity elements.

The continuous casting billet is heated to 1150℃ for 3.0 hours, unloaded from the furnace, descaled with 20MPa high pressure water, and then rolled in two stages: The first stage is recrystallization zone rolling, the rolling start temperature is 1150° C, and rolling is carried out in five passes, in which the deformation rate of two passes is ≥ 17%. The final rolling temperature is 1030 °C, and the thickness of the intermediate billet obtained after rolling in the recrystallization zone is 95 mm; the second stage of rolling is carried out outside the recrystallization zone. The initial rolling temperature is 850°C, the final rolling temperature is 830°C, the total deformation rate of rolling outside the recrystallization zone is ≥ 60%, and the thickness of the finished pipeline steel sheet is 26.4mm; after rolling, the steel sheet is sent to the cooling system through a 60 m long roller table with a transfer speed of 1.55 m/s. First, it is directly quenched in water, then air-cooled to the Ar ₃ temperature after water discharge, then quickly cooled by ACC, the final cooling temperature is 270 °C, and finally air-cooled to room temperature. The microstructure of the resulting pipeline steel is a very fine bainite. After testing, the strength and ductility values are as follows: Transverse yield strength Rt0.5: 510 MPa; tensile strength RM: 705 MPa, transverse ratio of yield strength to tensile strength Rt0.5/Rm=0.72; longitudinal yield strength 505 MPa, at -20 °C Charpy impact strength = 380 J, SA% (-20 °C) = 96%; longitudinal tensile strength Rm: 700 MPa, longitudinal uniform elongation Uel = 12.5%; the longitudinal ratio of yield strength to tensile strength is 0.72; longitudinal Rt1.5/Rt0.5=1.22, Rt2.0/Rt1.0=1.18, HIC test results are shown in Table 1.

Embodiment 4

A continuous casting billet with a thickness of not more than 370 mm is produced by continuous casting of molten steel corresponding to the chemical composition of the prepared pipeline steel sheet through a continuous casting machine. The chemical composition of the obtained continuous casting billet is: C: 0.039%, Si: 0.25%, Mn: 1.85%, S ≤ 0.002%, P ≤ 0.012%, Al: 0.03%, Cr: 0.25% , Nb + V + Ti: 0.10%, Ni: 0.45%, Cu: 0.25%, Ca: ≤ 0.002%, N: ≤ 0.0046%, Mo: 0.20%. The rest is Fe and unavoidable impurity elements.

The continuous casting billet is heated to 1160°C for 4.0 hours, unloaded from the furnace, descaled with 20 MPa high pressure water, and then rolled in two stages: The first stage is rolling in the recrystallization zone, the initial rolling temperature is 1140 °C, and rolling is carried out in five passes, in which the deformation rate of two passes is ≥ 17%. The final rolling temperature is 1050°C, and the thickness of the intermediate billet obtained after rolling in the recrystallization zone is 110 mm; the second rolling step is performed outside the recrystallization zone. The initial rolling temperature is 870°C, the final rolling temperature is 840°C, the total deformation rate of rolling outside the recrystallization zone is ≥ 60%, and the thickness of the finished pipeline steel sheet is 33mm; after rolling, the steel sheet is sent to the cooling system through a roller table 85 m long with a transfer speed of 2.0 m/s. First, it is directly quenched in water, then air-cooled to Ar ₃ temperature after water discharge, then quickly cooled by ACC, the final cooling temperature is 280 °C, and finally air-cooled to room temperature. The microstructure of the resulting pipeline steel is a very fine bainite. After the test, the strength and ductility values are as follows: transverse yield strength Rt0.5: 485 MPa; tensile strength Rm: 710 MPa, cross ratio of yield strength to tensile strength Rt0.5/Rm=0.68; longitudinal yield strength 475 MPa, at -20 °C Charpy impact strength = 420 J, SA% (-20 °C) = 85%; longitudinal tensile strength Rm: 695 MPa, longitudinal uniform elongation Uel = 12.5%; the longitudinal ratio of yield strength to tensile strength is 0.68; longitudinal Rt1.5/ Rt0.5 = 1.23, Rt2.0/Rt1.0 = 1.17, HIC test results are shown in Table 1.

Table 1 HIC Resistance of X80 Pipe Steel in Each Embodiment

Embodiment HIC test standard: soak in NACE tm0284-2004 a solution for 96 hours Crack length index % Crack Width Index % Crack sensitivity % 1 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 4 0 0 0 0 0 0 0 0 0

Claims (6)

1. Pipeline steel having both HIC resistance and deformation resistance, characterized in that the applied alloy composition is C: 0.015% to 0.039%, Si: 0.15% to 0.35%, Mn: 1.6% to 1 .9%, S: ≤ 0.002%, P: ≤ 0.012%, Al: 0.02-0.045%, Cr: 0.15-0.35%, 0.05 ≤ Nb + V + Ti ≤ 0.1% , Nb, V and Ti are not equal to 0, Ni: 0.15-0.50%, Cu: 0.01-0.25%, Ca: ≤ 0.002%, N: ≤ 0.0046%, Mo: 0, 01–0.20%, and the balance is Fe and unavoidable impurity elements, while the transverse yield strength of the product is Rt0.5 490–550 MPa, the transverse tensile strength Rm ≥ 710 MPa, the transverse ratio of yield strength to ultimate strength Rt0. 5/Rm ≤ 0.78, at -20°C Charpy impact strength greater than or equal to 350 J, at -20°C drop shear area SA% ≥ 90%; longitudinal yield strength 460–530 MPa; longitudinal tensile strength greater than or equal to 690 MPa, longitudinal uniform elongation Uel ≥ 11%, longitudinal ratio of yield strength to tensile strength less than or equal to 0.77; longitudinal stress factor Rt1.5/Rt0.5≥1.18, Rt2.0/Rt1.0≥1. 2. Pipeline steel according to claim 1, characterized in that the product is a bainite single-phase structure, and the grain size of bainite refers to points from 11.5 to 12. 3. A method for producing a pipeline steel having both HIC resistance and deformation resistance according to claim 1 or 2, characterized in that the continuous casting billet is heated to 1120–1160°C for 3–4 hours, unloaded from the furnace, scale is removed with water at a pressure of 20 MPa, and then rolled in two stages: the first stage is a multi-pass rolling in the recrystallization zone, while the initial rolling temperature is 1110-1150°C, the final rolling temperature is 1030-1080°C, and the two-pass deformation rate is 19% or more; the second rolling step is performed outside the recrystallization zone; the initial rolling temperature is 830-900°C, the final rolling temperature is 750-840°C, the cumulative deformation rate of rolling outside the recrystallization zone is 70% or more, after rolling, the steel sheet is sent to the cooling system through a 45-95m long roller table with a gear speed V=a*H, where H is the steel thickness in mm, a=0.05–0.08 m/(s*mm); first, direct water quenching is performed, then air-cooling to Ar ₃ temperature after water is drained, then rapid cooling is performed; the final cooling temperature is 280° C., straightening is performed while the steel sheet is still warm, and finally air-cooled to room temperature to obtain a pipeline steel having both HIC resistance and high deformation resistance. 4. The method according to claim 3, characterized in that ACC water cooling is used for rapid cooling in the cooling system.

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