A low yield ratio x90 grade pipeline steel hot-rolled coil and a manufacturing method thereof

Abstract

The present application relates to a kind of low X90 grade pipeline steel hot-rolled coil of ratio of yield strength, chemical composition includes by weight percentage:C 0.05-0.07%, Si 0.20-0.40%, Mn 1.50-1.90%, Nb0.05-0.09%, Ti 0.01-0.02%, Cr 0.10-0.30%, Mo 0.10-0.20%, Ni 0.10-0.20%, 0≤P≤0.012%, 0≤S≤0.005%, Als 0.015-0.035%, the rest is Fe and inevitable impurities.The present application also relates to a kind of low X90 grade pipeline steel hot-rolled coil of ratio of yield strength manufacturing method.Through the technical scheme of the present application, the present application can effectively reduce the yield ratio in the production and application of X90 grade pipeline steel hot-rolled coil.

Description

Technical Field

[0001] This invention relates to the field of pressure processing of microalloyed steel sheets and strips, and more specifically, to a low yield strength ratio X90 grade pipeline steel hot-rolled coil and its manufacturing method. Background Technology

[0002] As the most economical and efficient mode of transportation for oil and natural gas, pipeline transportation has advantages such as being less affected by external environmental factors such as climate and geology, and having lower construction and operating costs. As oil and natural gas extraction gradually extends to remote areas such as polar regions and deserts, the transportation distances for oil and natural gas are constantly increasing. To improve transportation efficiency, pipelines are also developing towards higher strength, larger diameter, and higher transmission pressure. With the increase in pipeline steel grades, the yield strength ratio also increases, which leads to a decrease in the strain hardening index and a reduction in the failure safety margin, becoming a technical challenge restricting the application of high-grade pipeline steel. The industry has undertaken technical research to address this challenge and has achieved certain results.

[0003] Chinese patent publication CN103276314A, entitled "A Low Yield-to-Strength Ratio and High Toughness X80 Pipeline Steel Plate and Its Manufacturing Method," proposes a steel plate with the following composition: C: 0.036-0.060%, Si: 0.15-0.40%, Mn: 1.65-1.90%, P≤0.012%, S≤0.0015%, Ni: 0.15-0.40%, Mo: 0.10-0.30%, Cr: 0.30-0.50%, Cu: ≤0.30%, Nb: 0.035-0.055%, Ti: 0.005-0.030%, Al: 0.020-0.050%, N≤0.008%, with the remainder being Fe and unavoidable impurities. The process flow is smelting-continuous casting-slab heating-TMCP rolling-controlled cooling-straightening-quenching and tempering treatment, yielding R... t0.5 ≥555MPa, R m ≥625MPa, yield strength ratio ≤0.82, A 50 X80 pipeline steel plate with ≥30% KV2≥240J at -40℃ and DWTT SA≥85% at -30℃, and a strength difference of ≤30MPa between the same steel plate and the steel plate.

[0004] Chinese patent publication CN103667911A, entitled "Hot-rolled steel plate with low yield strength ratio X100 high-grade pipeline steel and its manufacturing method," proposes a hot-rolled steel plate with the following composition: C: 0.03-0.08%, Si: 0.10-0.50%, Mn: 1.50-2.00%, P≤0.010%, S≤0.005%, Nb: 0.040-0.060%, Ti: 0.015-0.040%, Ni: 0.15-0.40%, Mo: 0.15-0.40%, Alt: 0.01-0.05%, with the remainder being Fe and unavoidable impurities. The plate is prepared using a process of hot metal pretreatment, converter smelting, ladle refining, continuous casting, slab heating, descaling, rolling, cooling, and tempering. 0.5 ≥710MPa, R m ≥850MPa, yield strength ratio ≤0.85, elongation after fracture A 50 ≥30%, A at 0℃ kv X100 pipeline steel plate with DWTT SA≥85% at ≥220J and 0℃.

[0005] Both inventions are applicable to medium plate rolling and employ a TMCP rolling-controlled cooling-straightening-tempering process to obtain steel plates with properties meeting the requirements for relevant pipeline steel strength and achieving a low yield strength ratio. However, the process path involved in these inventions involves controlled rolling and cooling + ultra-fast cooling + offline quenching and tempering, which cannot be implemented in coil production. Furthermore, the scope of these inventions does not cover X90 steel grade, and the composition also differs.

[0006] Therefore, existing technologies need to be improved. Summary of the Invention

[0007] To address the problem of excessively high yield strength ratio in the current production and application of high-grade X90 pipeline steel hot-rolled coils, this invention provides a manufacturing process for X90 pipeline steel hot-rolled coils with a low yield strength ratio. This process achieves a yield strength ratio of no more than 0.90 at the X90 steel grade strength while maintaining good low-temperature toughness. This invention provides a low yield strength ratio X90 pipeline steel hot-rolled coil and its manufacturing method. Through a smelting-continuous casting-controlled rolling and cooling-slow cooling process after coiling, a pipeline steel hot-rolled coil with a tensile strength of ≥695MPa, a yield strength of 625-775MPa, a yield strength ratio of no more than 0.85, an elongation of ≥20%, an impact energy of ≥190J (single value) and ≥250J (average value) at -20℃, and a shear area of ​​≥70% (single value) and ≥85% (average value) in a drop hammer test at -15℃ is obtained.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] According to one aspect of the present invention, a hot-rolled coil of X90 grade pipeline steel with a low yield strength ratio is provided, the chemical composition of which, by weight percentage, comprises: C 0.05-0.07%, Si 0.20-0.40%, Mn 1.50-1.90%, Nb 0.05-0.09%, Ti 0.01-0.02%, Cr 0.10-0.30%, Mo 0.10-0.20%, Ni 0.10-0.20%, 0 < P ≤ 0.012%, 0 < S ≤ 0.005%, Als 0.015-0.035%, with the remainder being Fe and unavoidable impurities.

[0010] In one embodiment of the present invention, the cold crack sensitivity index Pcm ≤ 0.194%.

[0011] In one embodiment of the present invention, the microstructure of the hot-rolled pipeline steel coil is a multiphase microstructure composed of lath bainite, granular bainite, quasi-polygonal ferrite and M / A islands.

[0012] In one embodiment of the present invention, the hot-rolled pipeline steel coil has a tensile strength ≥695MPa, a yield strength of 625-775MPa, a yield strength ratio ≤0.85, an elongation ≥20%, an impact energy of -20℃ with a single value ≥190J and an average impact energy ≥250J, and a drop hammer test shear area of ​​-15℃ with a single value ≥70% and an average value ≥85%.

[0013] According to another aspect of the present invention, a method for manufacturing a hot-rolled pipeline steel coil with a low yield strength ratio X90 grade as described above is provided, comprising the following steps:

[0014] 1) Slabs are obtained by using a process of hot metal pretreatment - converter smelting - ladle refining - vacuum smelting - calcium treatment - continuous casting;

[0015] 2) The slab is fed into the heating furnace for heating. The furnace entry temperature is <400℃ and the furnace exit temperature is 1180-1220℃.

[0016] 3) After the heated slab is descaled under high pressure, it is fed into a roughing mill for roughing. The final rolling temperature of the roughing mill is ≥980℃ to obtain an intermediate slab.

[0017] 4) The intermediate billet is fed into the cooling system to reduce the temperature of the intermediate billet to below 960℃, with a cooling rate of 10-15℃ / s;

[0018] 5) The cooled intermediate billet is fed into the finishing mill for rolling. The initial rolling temperature of the finishing mill is ≤950℃, and the final rolling temperature is 830-870℃.

[0019] 6) The finished slab is fed into the laminar flow cooling section for accelerated cooling at a rate of 20-30℃ / s and a final cooling temperature of 350-400℃, and then coiled.

[0020] 7) Place the coiled plate in a heat preservation device for a period of time, then take it out and air cool it to room temperature to obtain pipeline steel hot-rolled coil.

[0021] In one embodiment of the present invention, in step 1), the thickness of the obtained slab is 200-230 mm.

[0022] In one embodiment of the present invention, in step 2), the furnace time is 180-250 min.

[0023] In one embodiment of the present invention, in step 3), the rough rolling is performed in 5 passes, and the relative deformation per pass is controlled between 20% and 30%. The thickness of the intermediate billet obtained after rough rolling is 52-60 mm.

[0024] In one embodiment of the present invention, in step 5), the finishing rolling is performed in 5-7 passes, and the cumulative deformation of the finishing rolling is not less than 80%.

[0025] In one embodiment of the present invention, in step 7), the surface temperature of the outer ring of the coil is maintained at 400±20℃ and the heat preservation time is 30-50min.

[0026] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0027] This invention can effectively reduce the yield strength ratio of hot-rolled coils of X90 grade pipeline steel. Attached Figure Description

[0028] Figure 1 The diagram shows the microstructure of X90 pipeline steel with low yield strength ratio in Example 1 provided by the present invention, showing that the microstructure is a multiphase structure composed of lath bainite, granular bainite, quasi-polygonal ferrite and M / A islands;

[0029] Figure 2 The diagram shows the microstructure of X90 pipeline steel with low yield strength ratio in Example 2 of the present invention, which shows a multiphase microstructure consisting of lath bainite, granular bainite, quasi-polygonal ferrite and M / A islands. Detailed Implementation

[0030] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0031] This invention provides a hot-rolled coil of X90 grade pipeline steel with a low yield strength ratio. The chemical composition, by weight percentage, includes: C 0.05-0.07%, Si 0.20-0.40%, Mn 1.50-1.90%, Nb 0.05-0.09%, Ti 0.01-0.02%, Cr 0.10-0.30%, Mo 0.10-0.20%, Ni 0.10-0.20%, 0 < P ≤ 0.012%, 0 < S ≤ 0.005%, Als 0.015-0.035%, with the remainder being Fe and unavoidable impurities.

[0032] In the aforementioned low yield strength ratio X90 grade pipeline steel hot-rolled coils, the cold cracking sensitivity index Pcm ≤ 0.194%; the microstructure of the pipeline steel hot-rolled coils is a multiphase microstructure composed of lath bainite, granular bainite, quasi-polygonal ferrite, and M / A islands; the tensile strength of the pipeline steel hot-rolled coils is ≥ 695 MPa, the yield strength is 625-775 MPa; the yield strength ratio is ≤ 0.85; the elongation is ≥ 20%; the single impact energy at -20℃ is ≥ 190 J, and the average impact energy is ≥ 250 J; the single shear area in the drop hammer test at -15℃ is ≥ 70%, and the average is ≥ 85%.

[0033] Furthermore, the present invention provides a method for manufacturing the low yield strength ratio X90 grade pipeline steel hot-rolled coil as described above, comprising the following steps:

[0034] (1) A slab is obtained by using a process of hot metal pretreatment-converter smelting-ladle refining-vacuum smelting-calcium treatment-continuous casting;

[0035] (2) The slab is sent into the heating furnace for heating. The furnace temperature is <400℃ and the furnace temperature is 1180-1220℃.

[0036] (3) After the heated slab is descaled under high pressure, it is sent to the roughing mill for roughing. The final rolling temperature of the roughing mill is ≥980℃ to obtain the intermediate slab.

[0037] (4) The intermediate billet is fed into the cooling system to reduce the temperature of the intermediate billet to below 960°C, and the cooling rate is 10-15°C / s.

[0038] (5) The cooled intermediate billet is fed into the finishing mill for rolling. The starting rolling temperature of the finishing mill is ≤950℃ and the finishing rolling temperature is 830-870℃.

[0039] (6) The finished slab is sent to the laminar flow cooling section for accelerated cooling at a rate of 20-30℃ / s and a final cooling temperature of 350-400℃, and then coiled.

[0040] (7) The coiled plate is placed in a heat preservation device for a period of time, and then taken out and air-cooled to room temperature to obtain pipeline steel hot-rolled coil.

[0041] In the above manufacturing method, in step (1), the thickness of the obtained slab is 200-230 mm; in step (2), the furnace time is 180-250 min; in step (3), the rough rolling adopts 5 passes, the relative deformation of a single pass is controlled between 20% and 30%, and the thickness of the intermediate slab obtained after rough rolling is 52-60 mm; in step (5), the finish rolling adopts 5-7 passes, and the cumulative deformation of the finish rolling is not less than 80%; in step (7), the surface temperature of the outer ring of the coil is guaranteed to be 400±20℃, and the heat preservation time is 30-50 min.

[0042] The technical solutions of the present invention will be described in detail below through specific embodiments.

[0043] The purpose of this invention is to provide a hot-rolled pipeline steel coil with a low yield strength ratio of X90 grade and its manufacturing method. The hot-rolled pipeline steel coil has a tensile strength of 695 MPa or higher, a yield strength of 625-775 MPa, a yield strength ratio of not more than 0.85, an elongation of 20% or higher, an impact energy of 190 J or higher at -20℃ and an average impact energy of 250 J or higher, and a shear area of ​​not less than 70% and not less than 85% in a drop hammer test at -15℃.

[0044] To achieve the above objectives, the present invention provides the chemical composition of the aforementioned low yield strength ratio X90 pipeline steel, comprising, by weight percentage: C 0.05-0.07%, Si 0.20-0.40%, Mn 1.50-1.90%, Nb 0.05-0.09%, Ti 0.01-0.02%, Cr 0.10-0.30%, Mo 0.10-0.20%, Ni 0.10-0.20%, 0 < P ≤ 0.012%, 0 < S ≤ 0.005%, Als 0.015-0.035%, with the remainder being Fe and unavoidable impurities.

[0045] Based on the upper limit of the alloy composition of the steel plate, the cold cracking sensitivity index P was calculated. cm =0.194%, the calculation formula is: P cm =C+Si / 30+(Mn+Cu+Cr) / 20+Ni / 60+Mo / 15+V / 10+5B, where: each element symbol in the formula represents its weight percentage in the steel plate.

[0046] Regarding the chemical composition of the hot-rolled coils described above in this invention:

[0047] Carbon (C): The main function of carbon is to form carbides with microalloying elements such as niobium, molybdenum, and titanium, preventing abnormal grain growth and providing a certain precipitation strengthening effect during various stages of slab heating and rolling. Excessive carbon content will reduce the toughness and plasticity of steel and affect the performance of the weld zone. The carbon content in high-grade pipeline steel is usually below 0.10%. This invention controls the C content at 0.05-0.07%.

[0048] Silicon (Si): Silicon acts as a reducing agent and deoxidizer in the smelting of pipeline steel, while also providing solid solution strengthening effect. Its content is usually 0.20-0.40%. Excessive silicon content will reduce the plasticity, toughness and weldability of steel. Therefore, the Si content is generally not more than 0.40%.

[0049] Manganese (Mn): The main function of manganese is substitution solid solution strengthening, used to compensate for the strength decrease caused by the reduction in carbon content. Simultaneously, manganese can lower the austenitic transformation temperature, stabilize the austenitic phase, promote bainitic transformation, refine the transformation microstructure, and lower the ductile-brittle transition temperature. Excessive manganese content can easily cause center segregation, reducing the impact toughness of the steel and inducing anisotropy in mechanical properties. This invention controls the Mn content at 1.50%-1.90%.

[0050] Niobium (Nb) and Titanium (Ti): Niobium and titanium are the main microalloying elements. During different stages of slab heating and hot rolling, the precipitation of carbonitrides refines the grains and strengthens the steel. Niobium refines austenite grains and increases the austenite recrystallization temperature, while titanium precipitates carbonitrides at higher temperatures, pinning grain boundaries and refining weld grains. This invention controls the Nb content to 0.05-0.09% and the Ti content to 0.01-0.02%; to increase the effective titanium content, the nitrogen content should be limited to below 0.005%.

[0051] Chromium (Cr): During the controlled cooling stage, chromium can promote the formation of acicular ferrite or bainite and improve the corrosion resistance of pipeline steel to a certain extent.

[0052] Molybdenum (Mo): The main functions of molybdenum are to improve the hardenability of steel, enhance the uniformity of the surface and core microstructure in thick steel, inhibit the transformation of proeutectoid ferrite, promote the transformation of acicular ferrite or low-carbon bainite, increase the dislocation density in the microstructure, improve the impact energy of steel, and enhance its crack resistance. Simultaneously, molybdenum also promotes the fine dispersion of the second phase of titanium, thereby improving the strength and toughness of the steel.

[0053] Nickel (Ni): The main function of nickel is to improve the hardenability of steel, resulting in a uniform bainitic structure across thick steel plates of varying thicknesses. Additionally, its combination with chromium can promote the formation of the martensite (M / A) components.

[0054] In addition, the present invention also provides a method for manufacturing the above-mentioned low yield strength ratio X90 pipeline steel hot-rolled coil, including a smelting process and a rolling process.

[0055] The smelting process includes: hot metal pretreatment → converter smelting → ladle refining → vacuum smelting → calcium treatment → continuous casting, through which slabs with a thickness of 200-230mm are obtained.

[0056] The rolling process includes: slab reheating → descaling → rough rolling → finish rolling → accelerated cooling → coiling → heat holding and cooling, and is detailed as follows:

[0057] The above-mentioned continuously cast slabs are fed into a heating furnace with an inlet temperature of <400℃, an outlet temperature of 1180-1220℃, and a furnace time of 180-250 min.

[0058] After reheating, the slab is descaled under high pressure and then fed into a roughing mill, where it is rolled in 5 passes with a relative deformation of 20%-30% per pass. The inlet temperature of the final pass in the roughing mill is ≥980℃. The thickness of the intermediate slab obtained after roughing is 52-60mm.

[0059] The intermediate billet cooling system is put into operation with a cooling rate of 10-15℃ / s, reducing the temperature of the intermediate billet to below 960℃.

[0060] The above intermediate billets are rolled in a finishing mill in 5-7 passes. The cumulative deformation of the finishing mill is not less than 80%. The starting temperature of the finishing mill is ≤950℃ and the finishing temperature is 830-870℃.

[0061] After finishing, the steel plate enters the laminar flow cooling section, with a cooling rate of 20-30℃ / s and a final cooling temperature of 350-400℃, and is then coiled.

[0062] After being wound, the steel coil is placed in a heat preservation device to ensure that the surface temperature of the outer ring of the steel coil is 400±20℃ and the heat preservation time is 30-50 minutes. Then it is taken out and air-cooled to room temperature.

[0063] Regarding the manufacturing process of the hot-rolled coil of this invention:

[0064] Reheating of the slab: Its main function is to dissolve and homogenize the alloying elements. If the slab heating temperature is too low, the microalloying elements niobium and titanium will not dissolve effectively, thus affecting their subsequent precipitation and preventing effective grain refinement. If the slab heating temperature is too high, it may result in coarse grains, reducing the strength and toughness of the material. Therefore, this invention sets the heating temperature at 1180-1220℃.

[0065] Rough rolling: Its main function is to refine austenite grains by controlling the dynamic recrystallization of austenite. The deformation amount of a single pass in rough rolling must be greater than the critical deformation amount; otherwise, it is easy to lead to insufficient deformation at the thickness center. Therefore, the deformation amount of a single pass in rough rolling is controlled at ≥20%. This invention uses a larger austenite recrystallization deformation to promote the refinement of austenite recrystallization grains.

[0066] Finish rolling: Its main function is to provide nucleation energy and nucleation sites for ferrite phase transformation by controlling the deformation of unrecrystallized austenite grains. The ferrite nucleation rate is related to the cumulative deformation of finish rolling. The greater the cumulative deformation of finish rolling, the more dislocations and other substructures can be formed in the austenite grains. At the same time, the deformation energy storage can also provide energy fluctuations for ferrite nucleation. In this invention, the cumulative deformation of finish rolling is designed to be above 80% to ensure uniform and sufficient deformation throughout the thickness direction.

[0067] The finishing rolling temperature should be below the completely non-recrystallized austenite region to ensure that the internal substructure of the grains does not undergo significant recovery; the final rolling temperature should be set above the complete austenitizing temperature to ensure that ferrite does not undergo mixed crystal formation. Therefore, the initial finishing rolling temperature should not exceed 950℃, and the final rolling temperature should be in the range of 830-870℃.

[0068] To ensure the strength and toughness of the strip steel, it is necessary to form fine acicular structures in the thickness direction. Therefore, the strip steel needs to be cooled at a relatively high temperature at a cooling rate of 20-30℃ / s to avoid the formation of equiaxed ferrite and pearlite structures. The coiling temperature is 350-400℃ to refine the grains after phase transformation, increase the proportion of lath bainite and fine dispersed M / A islands, and avoid the formation of bulk martensite structures.

[0069] This invention also specifically requires that the steel coil be kept at a target temperature of 400±20℃ after winding, and the holding time be more than 30 minutes, in order to eliminate residual stress and generate a small amount of recovery, reduce microscale stress concentration, reduce yield strength ratio and improve plasticity.

[0070] This invention lists some key parameters used in the processes of Examples 1-4. The specific parameters are shown in Tables 1-2 below. Table 1 shows the chemical composition of the steel plates used in Examples 1-4 of this invention, and Table 2 shows the key parameters of the hot rolling process in Examples 1-4 of this invention.

[0071] Table 1. Chemical composition (wt% by mass) of the steel plates used in Examples 1-4

[0072] element C Si Mn P S Nb Ti Cr Mo Ni Als Example 1 0.052 0.37 1.87 0.010 0.003 0.064 0.015 0.12 0.14 0.15 0.032 Example 2 0.067 0.24 1.61 0.009 0.002 0.071 0.013 0.25 0.13 0.12 0.021 Example 3 0.068 0.31 1.55 0.009 0.003 0.056 0.019 0.24 0.17 0.11 0.018 Example 4 0.061 0.25 1.72 0.012 0.004 0.088 0.018 0.22 0.12 0.17 0.025

[0073] Table 2 Key parameters of hot rolling process in Examples 1-4

[0074]

[0075] The properties of the low yield strength ratio X90 grade pipeline steel hot-rolled coils prepared by the present invention through the above Examples 1-4 are shown in Table 3 below.

[0076] Table 3. Properties of hot-rolled pipeline steel coils prepared in Examples 1-4

[0077]

[0078] As can be seen from Table 3, the tensile strength R of the X90 grade pipeline steel hot-rolled coil with low yield strength ratio obtained by this invention is... m Above 695MPa, yield strength R t0.5 Pipeline steel hot-rolled coils with a strength of 625-775 MPa, a yield strength ratio not exceeding 0.85, an elongation of over 20%, an impact energy of over 190 J per unit and over 250 J per unit at -20℃, and a drop hammer test shear area of ​​over 70% per unit and over 85% per unit at -15℃. Therefore, this invention can effectively reduce the yield strength ratio of X90 pipeline steel hot-rolled coils.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Any modifications or equivalent substitutions made to the present invention without departing from the spirit and scope thereof should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for manufacturing a hot-rolled coil of X90 grade pipeline steel with a low yield strength ratio, characterized in that, Includes the following steps: 1) The slab is obtained by using a process of hot metal pretreatment - converter smelting - ladle refining - vacuum smelting - calcium treatment - continuous casting; 2) The slab is fed into the heating furnace for heating. The furnace entry temperature is <400℃ and the furnace exit temperature is 1180-1220℃. 3) After the heated slab is descaled under high pressure, it is sent to the roughing mill for rough rolling. The final rolling temperature of the roughing mill is ≥980℃ to obtain the intermediate slab. 4) The intermediate billet is fed into the cooling system to reduce the temperature of the intermediate billet to below 960℃, with a cooling rate of 10-15℃ / s; 5) The cooled intermediate billet is fed into the finishing mill for rolling. The initial rolling temperature of the finishing mill is ≤950℃, and the final rolling temperature is 830-870℃. 6) The finished slab is fed into the laminar flow cooling section for accelerated cooling at a rate of 20-30℃ / s and a final cooling temperature of 350-400℃, and then coiled. 7) Place the coiled plate in a heat preservation device and keep it warm for 30-50 minutes to ensure that the surface temperature of the outer ring of the coil plate is 400±20℃. Then take it out and air cool it to room temperature to obtain pipeline steel hot-rolled coil plate. The chemical composition of the low yield strength ratio X90 grade pipeline steel hot-rolled coil, by weight percentage, includes: C 0.05-0.07%, Si 0.20-0.40%, Mn 1.50-1.90%, Nb 0.05-0.09%, Ti 0.01-0.02%, Cr 0.10-0.30%, Mo 0.10-0.20%, Ni 0.10-0.20%, 0 < P ≤ 0.012%, 0 < S ≤ 0.005%, Al 0.015-0.035%, with the remainder being Fe and unavoidable impurities; the cold cracking sensitivity index Pcm of the hot-rolled pipeline steel coil is ≤0.194%; the microstructure of the hot-rolled pipeline steel coil is a multiphase microstructure composed of lath bainite, granular bainite, quasi-polygonal ferrite, and M / A islands; the tensile strength of the hot-rolled pipeline steel coil is ≥695MPa, the yield strength is 625-775 MPa; the yield ratio is ≤0.85; the elongation is ≥20%; the single impact energy at -20℃ is ≥190J, and the average impact energy is ≥250J; the single shear area at -15℃ drop hammer test is ≥70%, and the average shear area is ≥85%.

2. The manufacturing method according to claim 1, characterized in that, In step 1), the thickness of the obtained slab is 200-230 mm.

3. The manufacturing method according to claim 1, characterized in that, In step 2), the furnace time is 180-250 min.

4. The manufacturing method according to claim 1, characterized in that, In step 3), the rough rolling is performed in 5 passes, with the relative deformation per pass controlled between 20% and 30%, and the thickness of the intermediate billet obtained after rough rolling is 52-60 mm.

5. The manufacturing method according to claim 1, characterized in that, In step 5), the finishing rolling is carried out in 5-7 passes, and the cumulative deformation of the finishing rolling is not less than 80%.

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