CN114107816A - X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness and preparation method thereof - Google Patents

X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness and preparation method thereof Download PDF

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Publication number
CN114107816A
CN114107816A CN202111396784.0A CN202111396784A CN114107816A CN 114107816 A CN114107816 A CN 114107816A CN 202111396784 A CN202111396784 A CN 202111396784A CN 114107816 A CN114107816 A CN 114107816A
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equal
less
toughness
pipeline steel
strength
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郭朝海
夏继年
李国宝
汤化胜
孙风晓
杨贵玲
贾崇雪
王南辉
杨西亚
黄诚
于爽
雷凯
高龙永
王克柱
李贺
文雄
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SD Steel Rizhao Co Ltd
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SD Steel Rizhao Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite

Abstract

The invention relates to the technical field of pipeline steel metallurgy, in particular to an X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness and a preparation method thereof. Comprises the following components in percentage by weight: c: 0.030 to 0.060%, Si: 0.10-0.30%, Mn: 0.90-1.20%, P is less than or equal to 0.013%, S is less than or equal to 0.0020%, Nb: 0.025 to 0.055 percent, Ti: 0.010-0.030%, Cr: 0.15-0.30%, 0.0010-0.0040% of Ca, Als: 0.020-0.050%, less than or equal to 0.0030% of O, less than or equal to 0.0050% of N, less than or equal to 0.0002% of H, and the balance of Fe and inevitable impurities; wherein, O + N + H is less than or equal to 0.0080 percent. The invention reduces the production cost and has high toughness, acid resistance and corrosion resistance.

Description

X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness and preparation method thereof
Technical Field
The invention relates to the technical field of pipeline steel metallurgy, in particular to an X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness and a preparation method thereof.
Background
Pipeline transportation is one of the most efficient, economic, safe and environment-friendly modes for long-distance oil and gas transportation at present. The pipeline steel is widely applied to pipeline transportation engineering of petroleum, natural gas and the like. The method improves the grade of pipeline steel, and is an effective way for improving the oil and gas transmission efficiency and saving the pipeline construction cost. Meanwhile, with the continuous deepening of exploration and development of petroleum and natural gas, the environment for oil and gas exploitation is more and more severe. Therefore, higher requirements are provided for the properties of the pipeline steel such as strength, toughness, corrosion resistance and the like, particularly, the high-grade pipeline steel used in an acid environment is the variety with the most strict performance and quality requirements in the pipeline steel series, and due to the particularity of the use environment, extremely high requirements are provided for the component design of the steel, the purity of molten steel, the segregation control of a casting blank, the controlled rolling and controlled cooling process and the water average of metallurgical equipment. H2Corrosion damage by S is one of the main forms of pipeline corrosion damage. For transport containing H2The petroleum and natural gas medium of S requires that the pipeline steel has HIC (hydrogen induced cracking) resistance and SSC (sulfide stress cracking) resistance so as to ensure the safety of the pipeline steel product serving in an acidic environment.
Acid-fast pipeline steel application grades are mainly X52MS, X60MS, while the advanced mainstream steel grade is X65 MS. In the prior art, the high toughness requirement of high acidity grade pipeline steel is met and the high acidity corrosion resistance property is achieved mainly by adopting low C and low Mn, adopting Nb, V and Ti microalloying and adding alloy elements such as Cr, Cu, Ni and Mo. The expensive alloy elements such as Ni, Cu, Mo and the like cause the production cost of the pipeline steel to be greatly increased due to high price, and the popularization and application of the high-grade acid-resistant pipeline steel are seriously limited.
Patent application with publication number CN102021476A discloses "a low-cost acid-resistant pipeline steel hot-rolled coil and a manufacturing method thereof", which comprises the following chemical components and main processes: c: 0.04-0.10%, Si:0.05 to 0.50%, Mn: 1.00-1.70%, P is less than or equal to 0.015%, S is less than or equal to 0.002%, Nb is less than or equal to 0.08%, Ti: 0.005-0.030%, Als: 0.010-0.050%, Ca: 0.0010-0.0040 percent, less than or equal to 0.0060 percent of N, less than or equal to 0.0002 percent of H, less than or equal to 0.0010 percent of O, no addition of noble alloy elements such as Cu, Ni and Mo, the final cooling temperature is 550-700 ℃, the specification Rt0.5 of 6.25 and 7.0mm of finished steel coils is less than or equal to 350MPa, and the Rm is less than or equal to 450MPa, and the steel belongs to low-strength level acid-resistant pipeline steel.
Patent publication No. CN100359035C discloses "X65 pipeline steel for acidic environment and manufacturing method thereof", which comprises the chemical components of C:0.02 to 0.05%, Si: 0.10 to 0.50%, Mn: 1.20-1.50%, P: 0.004-0.012%, less than or equal to 0.0020% of S, 0.05-0.07% of Nb, 0.005-0.025% of Ti, 0.050-0.195% of Mo, less than or equal to 0.35% of Cu, less than or equal to 0.35% of Ni, less than or equal to 0.0080% of N, 0.0015-0.0045% of Ca and more than or equal to 2.0% of Ca/S. In the embodiment, noble alloy elements such as Cu, Ni and Mo are added, and the content of Nb is 0.05-0.07%, so that the cost is high.
The patent publication No. CN104099522B discloses a method for manufacturing copper-nickel-free acid-resistant pipeline steel X52MS and a hot rolled plate coil thereof, which mainly comprises 0.02-0.06% of C, 0.05-0.35% of Si, 1.0-1.4% of Mn, less than or equal to 0.018% of P, less than or equal to 0.003% of S, 0.10-0.50% of Cr, 0.005-0.10% of Ti, 0.005-0.10% of Nb and 0-0.05% of V. The controlled cooling step adopts slow cooling measures such as sparse cooling or air cooling, the coiling temperature of the finished steel coil in the embodiment is 577 ℃ at the lowest, the final microstructure is polygonal ferrite and pearlite, and the brittle pearlite is easy to induce anti-HIC cracking and has potential adverse effects on anti-acidity.
The invention patent with publication number CN102851590A discloses acid-resistant low-manganese X70 pipeline steel and a production method thereof, and the chemical components of the steel are C: 0.05 to 0.07%, Si: 0.10 to 0.25%, Mn: 1.05-1.25%, P: 0-0.019%, S: 0 to 0.006%, Nb: 0.06-0.09%, Ti: 0.010-0.020%, Mo: 0.20 to 0.30%, Ni: 0.05 to 0.30%, Cu: 0.05-0.30%, Als: 0.015-0.040%, wherein the Nb content is more than or equal to 0.07%, the addition amounts of Cu, Ni and Mo are all more than or equal to 0.20%, the content is high, and the cost is high.
The invention patent of publication No. CN108893678A discloses an acid-resistant pipeline steel and a rolling method, and the chemical components are C: 0.014% -0.024%, Si: 0.10% -0.35%, Mn: 0.60% -0.80%, Nb: 0.030 to 0.070%, Ti: 0.006-0.020%, Cr: 1.00-1.10%, Ni: 0.10% -0.30%, Mo: 0.15-0.20%, Cu: 0.10% -0.30%, V: 0.010%, Al: 0.015-0.050%, and the balance of Fe and impurities. The content of C in the alloy is too low, the smelting production difficulty is great, Cu, Ni, Mo and the like are precious alloys and have large addition amount, the alloy cost is too high, and the production control difficulty is great by adopting a low-temperature (350-.
The invention patent application of publication No. CN111607739A discloses a low-cost HIC (hydrogen induced cracking) and SSC (sulfide stress cracking) resistant excellent pipeline steel and a manufacturing method thereof, wherein the chemical components and the mass percentage are as follows: 0.03% -0.06%, Si: 0.10-0.35%, Mn: 0.60% -0.95%, Nb: 0.025 to 0.060 percent of Ti: 0.006% -0.030%, Cr: 0.15% -0.45%, Al: 0.020-0.060 percent, less than or equal to 0.015 percent of P, less than or equal to 0.0020 percent of S, less than or equal to 0.0030 percent of O, less than or equal to 0.0002 percent of H and the balance of Fe and impurities, the final cooling temperature is controlled to be 450-500 ℃, the performance requirement of X52-grade low-strength pipeline steel under the low-temperature acidic working condition of 5.0-16 mm-20 ℃ is met, and the strength grade is not high.
The invention patent application of publication No. CN111235489A discloses a method for manufacturing X65MS acid-resistant pipeline steel, which comprises the following chemical components in percentage by mass: 0.03-0.05 Wt%, Si less than or equal to 0.15 Wt%, Mn: 1.25-1.35 Wt%, P is less than or equal to 0.015 Wt%, S is less than or equal to 0.0015 Wt%, Alt: 0.020-0.040 Wt%, Ti: 0.010-0.020 Wt%, Nb: 0.040% -0.050 Wt%, Cr: 0.20-0.25 Wt%, Ni: 0.10-0.20 Wt%, O is less than or equal to 0.0020 Wt%, N is less than or equal to 0.0040 Wt%, and the Ca/S ratio is more than or equal to 1.5; the balance of Fe and inevitable trace elements, the coiling temperature is controlled at 440-480 ℃, the production control difficulty is high, meanwhile, the high manganese content is added, the noble alloy Ni is added, and the alloy cost is relatively high.
In summary, in the prior art, in order to meet the requirements of high strength, high toughness and excellent HIC and SSC resistance of high-grade acid-resistant pipeline steel, precious alloy elements such as Cu, Ni and Mo need to be added, which seriously affects the market competitiveness and popularization and application of acid-resistant pipeline steel products of enterprises.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness and the preparation method thereof, which can meet the requirement of oil and gas pipelines on high-toughness pipeline steel in harsh application environments on the basis of obviously reducing the production cost.
In a first aspect, the invention provides a low-cost and high-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil which comprises the following components in percentage by weight: c: 0.030 to 0.060%, Si: 0.10-0.30%, Mn: 0.90-1.20%, P is less than or equal to 0.013%, S is less than or equal to 0.0020%, Nb: 0.025 to 0.055 percent, Ti: 0.010-0.030%, Cr: 0.15-0.30%, 0.0010-0.0040% of Ca, Als: 0.020-0.050%, less than or equal to 0.0030% of O, less than or equal to 0.0050% of N, less than or equal to 0.0002% of H, and the balance of Fe and inevitable impurities; wherein, O + N + H is less than or equal to 0.0080 percent
Furthermore, the X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness has the yield strength of 450-600 MPa, the tensile strength of 535-760 MPa, the yield ratio of not more than 0.93, the Charpy impact energy at the low temperature of minus 39 ℃ of not less than 300J, the drop hammer shear area of not less than 85 percent at the temperature of minus 30 ℃ and the thickness of 8-16 mm.
The content of C in the invention is 0.03-0.06%, and the toughness and welding performance of the steel can be improved by adopting lower content of C, and the HIC and SSC resistance of the pipeline steel can be improved; if the carbon content is lower than 0.03%, not only can the strength loss be too large, but also the smelting difficulty is increased; the content of C is more than 0.06 percent, which can aggravate the segregation of Mn and P elements in the steel, easily cause the formation of inclusions and banded structures, increase the probability of crack initiation and further reduce the HIC and SSC resistance.
In the invention, the content of Si is 0.10-0.30%, Si is a solid solution strengthening element and has a deoxidation effect, but the content of Si exceeds 0.30%, which can adversely affect the toughness of the pipeline steel-plastic.
In the invention, the content of Mn is 0.90-1.20%, Mn is a solid solution strengthening element and is also an easily segregated element, the content of Mn is properly reduced, the occurrence of a banded structure is avoided, segregation is reduced, and the HIC and SSC resistance of the pipeline steel is improved.
In the invention, the content of P is less than or equal to 0.013 percent, and the P element is a harmful element which causes zonal tissue and center segregation and reduces the HIC resistance and toughness of the material, and the content of P is reduced as much as possible.
The S content is less than or equal to 0.0020 percent, and sulfur is also a harmful element, so that the steel generates hot brittleness, and the toughness of the steel is reduced. In addition, S combines with Mn to form strip-shaped MnS inclusions which become the origin of hydrogen induced cracking, so that the S content should be controlled as much as possible.
In the invention, the content of Nb is 0.025-0.055%, Nb is a strong carbonitride forming element, and the combination of a niobium microalloying technology and a controlled rolling and controlled cooling process is adopted, so that the effects of fine grain strengthening and precipitation strengthening are fully exerted, the formation of an acicular ferrite structure is promoted, and the strength and the toughness of the steel are obviously improved.
The Ti content is 0.010-0.030%, the micro Ti treatment technology is adopted, the TiN is used for inhibiting the growth of high-temperature austenite grains, the austenite grains are refined, and the impact toughness of a welding heat affected zone is improved.
The Cr content is 0.15-0.30%, and proper amount of Cr element is added, so that the strength and toughness can be improved, a passive film can be formed, hydrogen is prevented from invading into a steel matrix, and the acid and corrosion resistance is improved.
The Ca content of the invention is 0.0010-0.0040%, and the calcium is used for carrying out the modification treatment of the inclusion, so that the inclusion is spheroidized, and the performance of the steel is improved.
In the invention, the content of Als is 0.020-0.050%, Al is an important deoxidizing element and a refined grain element, and the content of O and the refined grain size can be effectively reduced.
In the invention, the content of N is less than or equal to 0.0050 percent, the content of O is less than or equal to 0.0030 percent, the content of H is less than or equal to 0.0002 percent, N, O, H is a gas impurity element, which can reduce the purity of steel and form inclusions, and is not good for the toughness and the acid resistance of the steel, and the content should be controlled to be as low as possible.
The invention does not add noble alloy elements such as Cu, Ni, Mo and the like, obviously reduces the content of Nb element and obviously reduces the production cost.
According to the preparation method of the X65 MS-grade acid-resistant pipeline steel hot-rolled coil plate with low cost and high strength and toughness, the components are taken as raw materials, and the coil plate is obtained through converter smelting, LF + RH refining, continuous casting, casting blank heating, controlled rolling, ultra-fast cooling and laminar cooling.
Furthermore, S in molten iron fed into the converter during smelting is controlled to be less than or equal to 0.005%, and bottom blowing argon is adopted during the whole smelting process.
Further, the LF + RH refining process comprises the following steps: the LF treatment period is more than or equal to 15min, the vacuum pure degassing time is more than or equal to 8min, the soft blowing time is more than or equal to 12min, the O + N + H is controlled to be less than or equal to 0.0080%, and impurities in the steel are effectively removed or spheroidized by combining Ca modification treatment.
Further, the continuous casting process comprises the following steps: the continuous casting process is carried out in a whole protective pouring mode, secondary oxidation of molten steel is avoided, the superheat degree of a tundish is controlled at 15-25 ℃, a constant drawing speed is adopted for controlling, the drawing speed of a casting blank is 1.0-1.4 m/min, the fluctuation range of the liquid level of molten steel of a crystallizer is controlled within +/-3 mm, the low-power quality of the casting blank meets the requirement that the class C is less than or equal to 1.0, the center porosity is less than or equal to 0.5, and no intermediate cracks and surface defects exist; after continuous casting, the casting blank is slowly cooled for more than or equal to 48 hours, so that hydrogen gas fully overflows from the interior of the casting blank, the occurrence probability of hydrogen-induced cracks is reduced, the thickness of the casting blank is more than 200mm, and the condition that the subsequent rolling has a larger compression ratio is ensured.
Furthermore, the heating temperature of the casting blank is 1200-1240 ℃, and the heating time in the furnace is 180-260 min, so that the effect of the microalloy elements can be fully exerted.
Further, the controlled rolling adopts rough rolling and finish rolling; the rough rolling process comprises the following steps: in the rough rolling process, the recrystallization zone is controlled to roll to refine austenite grains, the outlet temperature of the rough rolling is controlled to be 1020-1060 ℃, the thickness of the intermediate blank after the rough rolling is more than 3 times that of the finished product of the steel coil, and the total compression ratio in the rough rolling stage is more than or equal to 70 percent; the finish rolling process comprises the following steps: in the finish rolling process, the combination of niobium microalloying and controlled rolling processes is adopted to carry out controlled rolling in a non-recrystallization area, the temperature of a finish rolling inlet is controlled to be 960-1000 ℃, the finish rolling temperature is 810-850 ℃, the rolling speed is 4-8 m/s, the total rolling reduction ratio of finish rolling is more than or equal to 70%, the cumulative reduction rate of 3 passes after finish rolling is more than or equal to 30%, so that the flattening of austenite grains along the rolling direction is ensured, the austenite grains are refined, the accumulation of austenite deformation zones is realized, and favorable conditions are created for the subsequent refining of ferrite tissues and precipitation of precipitated phases.
Further, the ultra-fast cooling and laminar cooling speed is 20-30 ℃/s, the steel is cooled to 500-560 ℃ for coiling, the formation of pearlite is inhibited, and the structure form which is favorable for acid resistance and mainly comprises acicular ferrite is obtained.
The invention has the beneficial effects that:
(1) the invention remarkably reduces the alloy cost by low-carbon, low-manganese, niobium-titanium composite microalloying and low-cost component design of properly adding chromium, obtains a high-quality casting blank by combining a clean steel smelting continuous casting process, obtains a tissue form mainly comprising acicular ferrite by matching with a unique controlled rolling and ultra-fast cooling process, and has uniform and fine tissue grain size, and the produced hot-rolled coil realizes excellent acid-resistant and corrosion-resistant properties on the basis of meeting the requirements of high strength and high toughness. The economical high-strength and high-toughness acid-resistant pipeline steel produced by controlling the components and the process meets the requirement of an oil-gas pipeline on high-performance pipeline steel in a severe application environment, has wide popularization and application prospect, and can generate remarkable economic and social benefits;
(2) the invention realizes the production and manufacture of the high-strength and high-toughness acid-resistant pipeline steel X65MS hot-rolled coil plate under a low-cost component system, the metallographic structure of the acid-resistant pipeline steel hot-rolled coil plate prepared by the invention is uniform and fine acicular ferrite and a small amount of polygonal ferrite, the average grain size is 12-13 grades, the strip structure is not existed, four types of nonmetallic inclusions are not more than 1, the strength performance meets the standard requirement of X65-grade pipeline steel, the yield strength Rt 0.5450-600 MPa, the tensile strength Rm 535-760 MPa, the yield ratio Rt0.5/Rm is not more than 0.93, the product can meet the high-toughness requirement that the-39 ℃ low-temperature summer ratio impact energy is not less than 300J and the-30 ℃ drop hammer shear area is not less than 85%, and simultaneously has excellent HIC (hydrogen induced cracking) and SSC (sulfide stress cracking) resistance, and meets the use requirements under the harsh service conditions of high pressure, low temperature, acidity and the like.
Drawings
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a microstructure diagram of a hot rolled coil produced in example 1 of an embodiment of the present invention.
FIG. 2 is a microstructure diagram of a hot rolled coil produced in example 1 of the embodiment of the present invention.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness, which is described in the embodiment, comprises the following components in percentage by weight: c: 0.052%, Si: 0.21%, Mn: 0.95%, P: 0.008%, S: 0.0014%, Als: 0.031%, Nb: 0.025%, Ti 0.018%, Cr: 0.21%, O: 0.0026%, N: 0.0032%, H: 0.0002% and the balance of Fe and inevitable impurities.
The preparation method of the X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness, which is described in the embodiment, comprises the following steps:
(1) smelting: smelting molten iron in a blast furnace and smelting the molten iron in a converter by using the components as raw materials, wherein S in the molten iron fed into the converter is controlled to be 0.003 percent, and argon is blown from the bottom in the whole smelting process;
(2) LF + RH refining: the LF treatment period is 24min, the vacuum pure degassing time is 9min, the soft blowing time is 12min, and impurities in the steel are effectively removed or spheroidized by combining with Ca modification treatment;
(3) continuous casting: the continuous casting process is carried out in a whole protective pouring way, secondary oxidation of molten steel is avoided, the superheat degree of a tundish is controlled at 21 ℃, the casting blank is produced at a constant casting speed, the casting blank casting speed is 1.2m/min, the low-power quality of the casting blank meets class C0.5, and the continuous casting process is free of center porosity, intermediate cracks and surface defects; slowly cooling the casting blank for 48h at the lower line, wherein the thickness of the casting blank is 230 mm;
(4) heating: the heating temperature of the casting blank is 1218-;
(5) controlling rolling: rolling in a recrystallization zone in a rough rolling stage, controlling the temperature of a rough rolling outlet to 1050 ℃, controlling the thickness of an intermediate blank to be 45mm, and controlling the total compression ratio in the rough rolling stage to be 80%; rolling in a non-recrystallization area in a finish rolling stage, controlling the temperature of a finish rolling inlet to 990 ℃, controlling the temperature of a finish rolling to 840 ℃, rapidly rolling into a finished steel strip with the thickness of 8.02mm through 6 stands at the rolling speed of 7m/s, wherein the total rolling reduction ratio in the finish rolling stage is 82%, and the accumulated reduction ratio in 3 passes after the finish rolling stage is 35%;
(6) cooling and coiling: and after rolling, rapidly cooling the steel strip to 550 ℃ by adopting a front-mounted ultra-fast cooling and laminar cooling mode, coiling at a cooling speed of 25 ℃/s, and air-cooling the coiled steel strip to room temperature.
The thickness of the X65 MS-grade acid-resistant pipeline steel hot-rolled coil prepared in the embodiment is 8.02mm, and the product of the embodiment is subjected to coil-by-coil inspection, so that the yield strength Rt0.5 is 496-523 MPa, the tensile strength Rm is 562-583 MPa, the yield ratio Rt0.5/Rm 0.87-0.89 and the elongation A5035-38 percent completely meet the requirement of X65MS on tensile property. The impact energy (half size) at minus 39 ℃ is 128-145J, the fracture area of the impact fiber is 100%, and the drop hammer shear area at minus 30 ℃ is 100%, so that the high-strength low-temperature-resistant high-tenacity composite material has excellent low-temperature crack-arresting toughness. The microstructure of the steel coil is mainly acicular ferrite and a small part of polygonal ferrite, the grains are uniform and fine, the average grain size is 12.5 grade, the steel coil has no banded structure, and the detection of nonmetallic inclusions is 0.
Performing HIC performance inspection according to NACE TM0284 standard, taking 3 longitudinal samples at the positions of rolling plate widths 1/4 and 1/2, wherein the test solution is NACE TM0284-A solution, the test time is 96 hours, as shown in figure 1, no crack is observed on the section of the sample under a microscope of 100 times, no hydrogen bubbling occurs on the surface of the sample, the HIC resistance performance inspection data of the inspection sample is shown in table 1, the Crack Length Rate (CLR), the Crack Sensitivity Rate (CSR) and the Crack Thickness Rate (CTR) in the table 1 are all 0, the HIC resistance performance of the inspected sample meets the performance requirements that the CLR is less than or equal to 15 percent, the CSR is less than or equal to 2 percent, the CTR is less than or equal to 5 percent, the crack length of any section is not more than 5mm, and the bubble area is not more than 1 percent of the exposed area of the two broad surfaces.
TABLE 1 test sample HIC resistance test data of example 1
Figure BDA0003370189870000091
Sulfide stress corrosion cracking (SSC) testing was performed according to ASTM G39-99(2016) standard 4-point bend method and NACE TM0177-2016 standard, taking three longitudinal test specimens of 115X 5X 15mm each at a web width of 1/2. NACE TM0177-A solution was used for the test with a test time of 720 hours and a sample loading stress of 80% of the specified minimum yield strength. After the test sample is taken out of the test medium, the tensile surface of the test sample is observed under an X10 low power microscope, and all the test samples have no cracks, which indicates that the test sample is insensitive to sulfide stress corrosion cracking and is qualified in the test.
Example 2
The X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness, which is described in the embodiment, comprises the following components in percentage by weight: c: 0.045%, Si: 0.19%, Mn: 1.11%, P: 0.0010%, S: 0.0010%, Als: 0.031%, Nb: 0.035%, Ti 0.018%, Cr: 0.20%, O: 0.0024%, N: 0.0037%, H: 0.0001%, and the balance of Fe and inevitable impurities.
The preparation method of the X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness, which is described in the embodiment, comprises the following steps:
(1) smelting: smelting molten iron in a blast furnace by using the components as raw materials, smelting the molten iron in a converter, controlling S to be 0.004% in the molten iron fed into the converter, and adopting bottom blowing argon in the whole smelting process;
(2) LF + RH refining: the LF treatment period is 22min, the vacuum pure degassing time is 10min, the soft blowing time is 14min, and impurities in the steel are effectively removed or spheroidized by combining with Ca modification treatment;
(3) continuous casting: the continuous casting process is carried out in a whole protective pouring way, secondary oxidation of molten steel is avoided, the superheat degree of a tundish is controlled at 25 ℃, the casting blank is produced at a constant casting speed, the casting blank casting speed is 1.3m/min, the low-power quality of the casting blank meets class C0.5, and the continuous casting process is free of center porosity, intermediate cracks and surface defects; the casting blank is subjected to offline slow cooling for 60 hours, and the thickness of the casting blank is 230 mm;
(4) heating: the heating temperature of the casting blank is 1202-;
(5) controlling rolling: the coarse rolling stage is used for rolling in a recrystallization zone, the temperature of a coarse rolling outlet is controlled to be 1030 ℃, the thickness of an intermediate blank is 60.1mm, and the total compression ratio in the coarse rolling stage is 73%; rolling in a non-recrystallization area in a finish rolling stage, controlling the temperature of a finish rolling inlet to be 975 ℃ and the temperature of a finish rolling to be 820 ℃, rapidly rolling the steel strip into a finished steel strip with the thickness of 15.7mm through a 5-rack at the rolling speed of 4m/s, wherein the total rolling reduction ratio of the finish rolling stage is 74 percent, and the accumulated reduction ratio of 3 passes after the finish rolling stage is 30 percent;
(6) cooling and coiling: and after rolling, rapidly cooling the steel strip to 515 ℃ by adopting a front-mounted ultra-fast cooling and laminar cooling mode, coiling at a cooling speed of 25 ℃/s, and air-cooling the coiled steel strip to room temperature.
The thickness of the X65 MS-grade acid-resistant pipeline steel hot-rolled coil prepared in the embodiment is 15.7mm, and the product of the embodiment is subjected to coil-by-coil inspection, so that the yield strength Rt0.5 is 486-501 MPa, the tensile strength Rm is 554-573 MPa, the yield ratio Rt0.5/Rm 0.86-0.88 and the elongation A5035-38 percent completely meet the requirement of X65MS on tensile property. The impact energy (full size) at minus 39 ℃ is 316-347J, the section rate of the impact fiber is 100%, the drop weight performance is good, the drop weight shear area at minus 30 ℃ is more than 95%, and the low-temperature crack arrest toughness is excellent. The microstructure of the steel coil is mainly acicular ferrite and partial polygonal ferrite, the grains are uniform and fine, the average grain size is 12 grades, the steel coil has no banded structure, and the detection of nonmetallic inclusions is 0.
Performing HIC performance inspection according to NACE TM0284-2016 standard, taking 3 longitudinal samples at the positions of rolling plate widths 1/4 and 1/2, wherein the test solution is NACE TM0284-A solution, the test time is 96 hours, as shown in figure 2, no crack is observed on the section of the sample under a 100-time microscope, no hydrogen bubble appears on the surface of the sample, the HIC resistance performance inspection data of the inspection sample is shown in table 2, the Crack Length Rate (CLR), the Crack Sensitivity Rate (CSR) and the Crack Thickness Rate (CTR) are all 0, the HIC resistance performance of the inspected sample meets the performance requirements that the CLR is less than or equal to 15 percent, the CSR is less than or equal to 2 percent and the CTR is less than or equal to 5 percent, the crack length of any section is not more than 5mm, and the bubble area is not more than 1 percent of the exposed area of two broad surfaces.
Table 2 test sample HIC resistance test data of example 2
Figure BDA0003370189870000111
Sulfide Stress Cracking (SSC) testing was performed according to ASTM G39-99(2016) standard 4-point bend method and NACE TM0177-2016 standard, taking three longitudinal test specimens each measuring 115X 5X 15mm across the width 1/2 of the coil. NACE TM0177-A solution was used for the test with a test time of 720 hours and a sample loading stress of 80% of the specified minimum yield strength. After the test sample is taken out of the test medium, the tensile surface of the test sample is observed under an X10 low power microscope, and all the test samples have no cracks, which indicates that the test sample is insensitive to sulfide stress corrosion cracking and is qualified in the test.
From the above examples, it can be seen that the pipeline steel X65MS produced according to the components and processes of the invention has the advantages of high strength, high toughness, acid and corrosion resistance, and excellent comprehensive properties while the production cost is significantly reduced.
Although the present invention has been described in detail by referring to the drawings in connection with the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention.

Claims (9)

1. A low-cost high-strength-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil is characterized by comprising the following components in percentage by weight: c: 0.030 to 0.060%, Si: 0.10-0.30%, Mn: 0.90-1.20%, P is less than or equal to 0.013%, S is less than or equal to 0.0020%, Nb: 0.025 to 0.055 percent, Ti: 0.010-0.030%, Cr: 0.15-0.30%, 0.0010-0.0040% of Ca, Als: 0.020-0.050%, less than or equal to 0.0030% of O, less than or equal to 0.0050% of N, less than or equal to 0.0002% of H, and the balance of Fe and inevitable impurities; wherein, O + N + H is less than or equal to 0.0080 percent.
2. The low-cost high-strength-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil as claimed in claim 1, wherein the yield strength of the hot-rolled coil is 450-600 MPa, the tensile strength is 535-760 MPa, the yield ratio is less than or equal to 0.93, the Charpy impact energy at-39 ℃ is more than or equal to 300J, the drop-hammer shear area at-30 ℃ is more than or equal to 85%, and the thickness is 8-16 mm.
3. The preparation method of the low-cost and high-strength-and-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil plate according to claim 1 is characterized in that the coil plate is prepared by taking the components according to claim 1 as raw materials, and performing converter smelting, LF + RH refining, continuous casting, billet heating, controlled rolling, ultra-fast cooling and laminar cooling and coiling.
4. The method for preparing the low-cost and high-strength-and-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil as claimed in claim 3, wherein S is controlled to be less than or equal to 0.005% in molten iron entering a converter during smelting, and argon is blown from the bottom during the whole smelting process.
5. The method for preparing the low-cost and high-strength-and-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil plate as claimed in claim 3, wherein the LF + RH refining process comprises the following steps: the LF treatment period is more than or equal to 15min, the vacuum pure degassing time is more than or equal to 8min, the soft blowing time is more than or equal to 12min, the O + N + H is controlled to be less than or equal to 0.0080%, and impurities are removed by combining Ca modification treatment.
6. The method for preparing the low-cost and high-strength-and-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil plate as claimed in claim 3, wherein the continuous casting process comprises the following steps: the continuous casting process is carried out in a protective pouring mode in the whole process, the superheat degree of a tundish is controlled to be 15-25 ℃, and the casting blank drawing speed is 1.0-1.4 m/min; and (4) slowly cooling the casting blank after continuous casting, wherein the slow cooling time is more than or equal to 48 hours.
7. The method for preparing the low-cost and high-strength-and-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil plate as claimed in claim 3, wherein the casting blank heating temperature is 1200-1240 ℃, and the heating time in the furnace is 180-260 min.
8. The method for preparing the low-cost high-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil plate as claimed in claim 3, wherein the controlled rolling adopts rough rolling and finish rolling; the rough rolling process comprises the following steps: the outlet temperature of the rough rolling is controlled to be 1020-1060 ℃, the thickness of the intermediate blank after the rough rolling is more than 3 times of the thickness of the finished product of the steel coil, and the total compression ratio in the rough rolling stage is more than or equal to 70 percent; the finish rolling process comprises the following steps: the inlet temperature of finish rolling is controlled to be 960-1000 ℃, the finishing temperature is 810-850 ℃, the rolling speed is 4-8 m/s, the total reduction ratio of finish rolling is more than or equal to 70%, and the cumulative reduction ratio of 3 passes after finish rolling is more than or equal to 30%.
9. The method for preparing the low-cost and high-strength-and-toughness X65 MS-grade acid-resistant pipeline steel hot-rolled coil plate as claimed in claim 3, wherein the ultra-fast cooling and laminar cooling speed is 20-30 ℃/s, and the coil plate is cooled to 500-560 ℃ for coiling.
CN202111396784.0A 2021-11-23 2021-11-23 X65 MS-grade acid-resistant pipeline steel hot-rolled coil with low cost and high strength and toughness and preparation method thereof Pending CN114107816A (en)

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