CN113046630A - Thick pipeline steel and preparation method thereof - Google Patents
Thick pipeline steel and preparation method thereof Download PDFInfo
- Publication number
- CN113046630A CN113046630A CN202110168076.5A CN202110168076A CN113046630A CN 113046630 A CN113046630 A CN 113046630A CN 202110168076 A CN202110168076 A CN 202110168076A CN 113046630 A CN113046630 A CN 113046630A
- Authority
- CN
- China
- Prior art keywords
- cooling
- pipeline steel
- temperature
- steel
- rare earth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0006—Adding metallic additives
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
-
- 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
- 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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following 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
- C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
-
- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention provides thick pipeline steel and a preparation method thereof, wherein the pipeline steel comprises the following chemical components in percentage by mass: c: 0.04-0.07%, Si: 0.15-0.30%, Mn: 1.65-1.85%, P is less than or equal to 0.01%, S is less than or equal to 0.0020%, Alt: 0.03-0.05%, Nb: 0.07-0.09%, T i: 0.010-0.020%, N i: 0.25-0.35%, Cr: 0.2-0.35%, RE: 0.005-0.020%, Mo: 0.15-0.30%, and the balance of Fe and inevitable impurity elements, wherein Re is a rare earth element. After the pipeline steel provided by the invention is welded, the impact toughness of a base material at the temperature of minus 20 ℃ is 358-doped 384J, the impact toughness of a fusion line at the temperature of minus 10 ℃ is 305-doped 348J, the impact toughness of a coarse crystal area at the temperature of minus 10 ℃ is 318-doped 342J, and the toughness of the fusion line and the coarse crystal area is good.
Description
Technical Field
The invention belongs to the technical field of pipeline steel, and particularly relates to thick pipeline steel and a preparation method thereof.
Background
The pipeline steel is a kind of steel with special requirements for pipelines for conveying petroleum, natural gas and the like, and can be produced by a hot continuous rolling unit, a steckel mill or a medium plate mill according to different thicknesses, subsequent formation and the like, and is formed into a large-caliber steel pipe through spiral welding or UOE straight seam welding. In the welding process, the highest temperature to which each point on the base material, which is away from the welding seam by different distances, is heated is different, and the structure and the performance of the base material are influenced. The two sides of the welding seam are affected by welding heating, and the base material part with changed structure and mechanical property is a welding Heat Affected Zone (HAZ). The weld heat affected zone is a zone where the heating temperature of the welding material is different, so that the weld heat affected zone comprises a coarse crystal zone with coarse grains and a fusion line, and the impact toughness of the weld heat affected zone is very poor, which limits the application of the pipeline steel.
Patent No. CN101705412A "smelting method of line pipe steel for high heat input welding", improving impact toughness of base metal by means of oxide metallurgy, but does not describe thickness specification and impact toughness value. Patent No. CN 103084754A "a high strength and high toughness submerged arc welding wire for thick pipeline steel", which improves the toughness of a base material by changing a welding wire.
In the past, the patent focuses on improving the impact toughness of the base metal of the pipeline steel, changing the welding process condition, or utilizing inclusions to induce acicular ferrite to refine grains and pinning the grain boundary function by the inclusions in an oxide metallurgy mode, so that a preparation method of easily-welded high-toughness thick X80 pipeline steel is urgently needed, the impact toughness of a coarse grain region and a fusion line is improved, and the safety of domestic pipeline construction is ensured.
Disclosure of Invention
The invention provides thick pipeline steel and a preparation method thereof, and aims to solve the problems that in the prior art, after pipeline steel is welded, a coarse crystal area and a fusion line are low in toughness and short in service life.
In one aspect, the invention provides thick-gauge pipeline steel, which consists of the following chemical components in percentage by mass:
c: 0.04-0.07%, Si: 0.15-0.30%, Mn: 1.65-1.85%, P is less than or equal to 0.01%, S is less than or equal to 0.0020%, Alt: 0.03-0.05%, Nb: 0.07-0.09%, Ti: 0.010-0.020%, Ni: 0.25-0.35%, Cr: 0.2-0.35%, RE: 0.005-0.020%, Mo: 0.15-0.30%, and the balance of Fe and inevitable impurity elements, wherein Re is a rare earth element.
Further, the Re is at least one of: la, Ce and Y.
Further, the thickness of the pipeline steel is 25-60 mm.
Further, the pipeline steel is any one of the following: x80 and X90.
In another aspect, the present invention provides a method for preparing thick gauge pipeline steel, the method comprising,
smelting and continuously casting molten steel to obtain a plate blank; the slab comprises the following chemical components in percentage by mass: c: 0.03-0.05%, Si: 0.15-0.30%, Mn: 1.65-1.85%, P is less than or equal to 0.01%, S is less than or equal to 0.0020%, Alt: 0.03-0.05%, Nb: 0.07-0.09%, Ti: 0.010-0.020%, Ni: 0.25-0.35%, Cr: 0.2-0.35%, RE: 0.005-0.020%, Mo: 0.15-0.30%, and the balance of Fe and inevitable impurity elements, wherein Re is a rare earth element;
rolling and cooling the steel billet to obtain pipeline steel; the rolling comprises rough rolling and finish rolling, wherein the rough rolling starting temperature is 1080-1160 ℃, and the rough rolling finishing temperature is 980-1050 ℃; the finish rolling starting temperature is 840-870 ℃, and the finish rolling finishing temperature is 780-820 ℃.
Further, the cooling is two-stage cooling, wherein in the first-stage cooling, the start cooling temperature is 740-760 ℃, and the final cooling temperature is 530-540 ℃; in the second stage of cooling, the start cooling temperature is 520-530 ℃, and the final cooling temperature is 280-320 ℃.
Further, the cooling rate of the first-stage cooling is 25-30 ℃/s; the cooling rate of the second stage cooling is 15-20 ℃/s.
Further, the smelting comprises VD refining, and rare earth alloy is added 5-10min before the VD refining is finished, so that the mass fraction of the rare earth elements is 0.005-0.020%; in the rare earth alloy, the mass fraction of O is less than 0.015 percent, and the mass fraction of rare earth elements is more than 80 percent; in the VD refining process, the molten steel is circulated for more than or equal to 5min under the condition that the vacuum degree is less than or equal to 67Pa, the soft blowing is carried out for more than or equal to 10min after the vacuum breaking, and the flow rate of the soft blowing is 1-2 Nl/min/ton of steel.
Further, the smelting also comprises converter steelmaking, wherein the total mass fraction of FeO and MnO in the slag is controlled to be 0.5-2% in the converter steelmaking process, and the alkalinity of the slag is 3.5-6.0.
Furthermore, in the continuous casting process, protective casting is adopted, so that the change of the mass fraction of O in the molten steel before and after casting is less than 0.0002%.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
the invention provides thick pipeline steel and a preparation method thereof, which adopt Nb, V and Ti to match with rare earth elements, on one hand, the thick pipeline steel can form rare earth inclusions in molten steel, and the rare earth inclusions are distributed in a fine dispersion mode, so that the cleanliness of the molten steel is improved, and the impact toughness of the pipeline steel can be improved; on the other hand, in the high-temperature welding process, the rare earth inclusions in the heat affected zone can induce acicular ferrite in the crystal to refine crystal grains, and can also refine the sizes of precipitates of Nb, V and Ti, so that the impact toughness of a coarse crystal zone and a fusion line is improved. After the pipeline steel provided by the invention is welded, the impact toughness of a base material at the temperature of minus 20 ℃ is 358-doped 384J, the impact toughness of a fusion line at the temperature of minus 10 ℃ is 305-doped 348J, the impact toughness of a coarse crystal area at the temperature of minus 10 ℃ is 318-doped 342J, and the toughness of the fusion line and the coarse crystal area is good.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a structural diagram of a coarse grain region of thick pipeline steel after welding according to an embodiment of the present invention;
FIG. 2 is a structural diagram of a fusion line after welding thick pipeline steel according to an embodiment of the present invention.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
In order to solve the technical problems, the embodiment of the invention provides the following general ideas:
in one aspect, an embodiment of the present invention provides a thick gauge pipeline steel, where the pipeline steel is composed of the following chemical components by mass:
c: 0.04-0.07%, Si: 0.15-0.30%, Mn: 1.65-1.85%, P is less than or equal to 0.01%, S is less than or equal to 0.0020%, Alt: 0.03-0.05%, Nb: 0.07-0.09%, Ti: 0.010-0.020%, Ni: 0.25-0.35%, Cr: 0.2-0.35%, RE: 0.005-0.020%, Mo: 0.15-0.30%, and the balance of Fe and inevitable impurity elements, wherein Re is a rare earth element.
According to the invention, Nb, V and Ti are matched with rare earth elements, so that on one hand, rare earth inclusions can be formed in molten steel, and the rare earth inclusions are distributed in a fine and dispersed manner, thereby improving the cleanliness of the molten steel, and improving the impact toughness of pipeline steel; on the other hand, in the high-temperature welding process, the rare earth inclusions in the heat affected zone can induce acicular ferrite in the crystal to refine crystal grains, and can also refine the sizes of precipitates of Nb, V and Ti, so that the impact toughness of a coarse crystal zone and a fusion line is improved.
As an implementation of the embodiment of the present invention, the Re is at least one of: la, Ce and Y.
As an implementation mode of the embodiment of the invention, the thickness of the pipeline steel is 25-60mm, and the pipeline steel belongs to a medium plate.
As an implementation of an embodiment of the present invention, the pipeline steel includes, but is not limited to, the following designations: x80, X90.
In another aspect, the embodiment of the invention also provides a preparation method of the thick-gauge pipeline steel, which comprises the following steps,
smelting and continuously casting molten steel to obtain a plate blank; the slab comprises the following chemical components in percentage by mass: c: 0.04-0.07%, Si: 0.15-0.30%, Mn: 1.65-1.85%, P is less than or equal to 0.01%, S is less than or equal to 0.0020%, Alt: 0.03-0.05%, Nb: 0.07-0.09%, Ti: 0.010-0.020%, Ni: 0.25-0.35%, Cr: 0.2-0.35%, RE: 0.005-0.020%, Mo: 0.15-0.30%, and the balance of Fe and inevitable impurity elements, wherein Re is a rare earth element;
heating, rolling and cooling the billet to obtain pipeline steel; the rolling comprises rough rolling and finish rolling, wherein the rough rolling starting temperature is 1080-1160 ℃, and the rough rolling finishing temperature is 980-1050 ℃; the finish rolling starting temperature is 840-870 ℃, and the finish rolling finishing temperature is 780-820 ℃.
The purpose of controlling the rough rolling and finish rolling temperatures is to control the grain refinement in the recrystallized region and the dislocation and precipitation hardening in the non-recrystallized region.
As an implementation manner of the embodiment of the invention, the cooling is two-stage cooling, in the first-stage cooling, the start-cooling temperature is 740-760 ℃, the final-cooling temperature is 530-540 ℃, and the cooling rate is 25-30 ℃/s; in the second stage of cooling, the start cooling temperature is 520-530 ℃, the final cooling temperature is 280-320 ℃, and the cooling rate is 15-20 ℃/s.
The purpose of the two-stage cooling is to keep the hot zone from forming hot tissue and the non-hot zone to reduce stress. In the first stage of cooling, the starting cooling temperature is too high, the cooling rate is too low, a high-temperature structure is easily generated, and the toughness of the steel plate is influenced. The start-cooling temperature is too low, the cooling rate is too high, and the problems of large stress and plate shape are easily caused. In the second stage of cooling, the stress generated in the pipeline steel is large due to the overlarge cooling rate, and the toughness of the pipeline steel is reduced due to the overlarge cooling rate.
As an implementation mode of the embodiment of the invention, the smelting comprises VD refining, and rare earth alloy is added 5-10min before the VD refining is finished, so that the mass fraction of the rare earth elements is 0.005-0.020%; in the rare earth alloy, the mass fraction of O is less than 0.015 percent, and the mass fraction of rare earth elements is more than 80 percent; in the VD refining process, the molten steel is circulated for more than or equal to 5min under the condition that the vacuum degree is less than or equal to 67Pa, and the molten steel is blown softly for more than or equal to 10min after being broken.
As an implementation mode of the embodiment of the invention, the smelting further comprises converter steelmaking, the sum of the mass fractions of FeO and MnO in the slag is controlled to be 0.5-2% in the converter steelmaking process, and the alkalinity of the slag is 3.5-6.0.
The slag alkalinity in the invention refers to the mass fraction of CaO in the slag and SiO in the slag2The ratio of the mass fraction of (c). The effects of controlling the sum of the mass fractions of FeO and MnO in the slag and controlling the basicity of the slag are to control the O content and S content in the steel on the one hand and to control the inclusion components on the other hand. If the sum of the mass fractions of FeO and MnO is too high, the cleanliness of molten steel is deteriorated, large-size inclusions appear, and if the sum of the mass fractions of FeO and MnO is too low, the cost is increased; if the basicity of the slag is too high, the fluidity of the slag is deteriorated, and if the basicity of the slag is too low, the desulfurization effect is deteriorated.
As an implementation mode of the embodiment of the invention, in the continuous casting process, protective casting is adopted, so that the change of the mass fraction of O in molten steel before and after casting is less than 0.0002%.
Hereinafter, a thick gauge pipeline steel and a method for manufacturing the same according to the present invention will be described in detail with reference to examples, comparative examples and experimental data.
Example 1
The thickness specification of the X80 pipeline steel is 25mm, the smelting process is converter smelting → LF furnace refining → VD refining → continuous casting, the steel grade is produced, and the X80 pipeline steel comprises the following components:
the chemical components of the steel comprise the following components in percentage by mass: c: 0.05%, Si: 0.20%, Mn: 1.65%, P: 0.008%, S: 0.0012%, Alt: 0.035%, Nb: 0.075%, Ti: 0.015%, Ni: 0.25%, Cr: 0.25%, RE: 0.008%, Mo: 0.17% of rare earth elements including La and Ce, and the ratio of La to Ce is 1:2, as shown in tables 1 and 2.
The preparation method of the X80 pipeline steel comprises the procedures of steelmaking, rolling and cooling. Wherein the steel making is as follows: controlling the total content of FeO and MnO in percentage by weight in the slag to be 0.6% and the alkalinity of the slag to be 4.5; adding rare earth alloy 10min before VD refining, wherein the content of O in the rare earth alloy is 0.012 wt%, meanwhile, the proportion of rare earth elements in the alloy is 95%, and the balance is mainly Fe; under the condition that the VD vacuum degree is less than or equal to 67Pa, the vacuum circulation is carried out for 10min, and the soft blowing time is 12min after the air is broken; and protective pouring is carried out during ladle casting, secondary oxidation is reduced, and the O content before and after casting is changed to 0.0001%.
The rolling process sequentially comprises a first rolling and a second rolling, wherein in the first rolling, the initial rolling temperature is 1120 ℃, and the final rolling temperature is 1050 ℃. In the second rolling, the initial rolling temperature is 850 ℃, and the final rolling temperature is 780 ℃;
in the cooling process, the cooling process sequentially comprises two stages of cooling, wherein in the first stage of cooling, the start cooling temperature is 740 ℃, the end cooling temperature is 530 ℃, and the cooling rate is 25 ℃/s. In the second stage of cooling, the start cooling temperature is 520 ℃, the end cooling temperature is 300 ℃, and the cooling rate is 15 ℃/s.
Example 2
The thickness specification of the X80 pipeline steel is 60mm, the smelting process is converter smelting → LF furnace refining → VD refining → continuous casting, the steel grade is produced, and the X80 pipeline steel comprises the following components:
the chemical components of the steel comprise the following components in percentage by mass: c: 0.07%, Si: 0.25%, Mn: 1.70%, P: 0.007%, S: 0.0008%, Alt: 0.032%, Nb: 0.08%, Ti: 0.018%, Ni: 0.35%, Cr: 0.30%, RE: 0.02%, Mo: 0.30% of rare earth elements including La and Ce, and the ratio of La to Ce is 1:2, as shown in tables 1 and 2.
The preparation method of the X80 pipeline steel comprises the procedures of steelmaking, rolling and cooling. Wherein the steel making is as follows: controlling the total content of FeO and MnO in percentage by weight in the slag to be 2% and the alkalinity of the slag to be 6; adding rare earth alloy 10min before VD refining, wherein the content of O in the rare earth alloy is 0.015%, the proportion of rare earth elements in the alloy is 95%, and the balance is mainly Fe; under the condition that the VD vacuum degree is less than or equal to 67Pa, the vacuum circulation is carried out for 10min, and the soft blowing time is 15min after the air is broken; and protective pouring is carried out during ladle casting, secondary oxidation is reduced, and the O content before and after casting is changed to 0.0001%.
The rolling process sequentially comprises a first rolling and a second rolling, wherein in the first rolling, the initial rolling temperature is 1080 ℃, and the final rolling temperature is 980 ℃. In the second rolling, the initial rolling temperature is 840 ℃, and the final rolling temperature is 780 ℃;
in the cooling process, the cooling process comprises two-stage cooling, wherein in the first-stage cooling, the start-cooling temperature is 760 ℃, the end-cooling temperature is 540 ℃, and the cooling rate is 30 ℃/s. In the second stage of cooling, the start cooling temperature is 530 ℃, the end cooling temperature is 320 ℃, and the cooling rate is 20 ℃/s.
Example 3
The thickness specification of the X90 pipeline steel is 28mm, the smelting process is converter smelting → LF furnace refining → VD refining → continuous casting, the steel grade is produced, and the X90 pipeline steel comprises the following components:
the chemical components of the steel comprise the following components in percentage by mass: c: 0.06%, Si: 0.25%, Mn: 1.80%, P: 0.007%, S: 0.0008%, Alt: 0.032%, Nb: 0.06%, Ti: 0.018%, Ni: 0.2%, Cr: 0.30%, RE: 0.005%, Mo: 0.10% of rare earth elements including La and Ce, and the ratio of La to Ce is 1:2, as shown in tables 1 and 2.
The preparation method of the X90 pipeline steel comprises the procedures of steelmaking, rolling and cooling. Wherein the steel making is as follows: controlling the total content of FeO and MnO in percentage by weight in the slag to be 0.9%, and controlling the slag alkalinity to be 5.8; adding rare earth alloy 10min before VD refining, wherein the content of O in the rare earth alloy is 0.012 wt%, meanwhile, the proportion of rare earth elements in the alloy is 97%, and the balance is mainly Fe; under the condition that the VD vacuum degree is less than or equal to 67Pa, the vacuum circulation is carried out for 10min, and the soft blowing time is 12min after the air is broken; and protective pouring is carried out during ladle casting, secondary oxidation is reduced, and the O content before and after casting is changed to 0.0001%.
The rolling process sequentially comprises a first rolling and a second rolling, wherein in the first rolling, the initial rolling temperature is 1120 ℃, and the final rolling temperature is 1030 ℃. In the second rolling, the initial rolling temperature is 860 ℃, and the final rolling temperature is 810 ℃;
in the cooling process, the cooling process comprises two stages of cooling, wherein in the first stage of cooling, the start cooling temperature is 750 ℃, the end cooling temperature is 540 ℃, and the cooling rate is 28 ℃/s. In the second stage cooling, the start cooling temperature is 520 ℃, the end cooling temperature is 300 ℃ and the cooling rate is 17 ℃/s.
Example 4
The thickness specification of the X90 pipeline steel is 35mm, the smelting process is converter smelting → LF furnace refining → VD refining → continuous casting, the steel grade is produced, and the X90 pipeline steel comprises the following components:
the chemical components of the steel comprise the following components in percentage by mass: c: 0.06%, Si: 0.25%, Mn: 1.80%, P: 0.007%, S: 0.0008%, Alt: 0.032%, Nb: 0.06%, Ti: 0.018%, Ni: 0.2%, Cr: 0.30%, RE: 0.015%, Mo: 0.10% where RE is a rare earth element, including Y, as shown in tables 1 and 2.
The preparation method of the X90 pipeline steel comprises the procedures of steelmaking, rolling and cooling. Wherein the steel making is as follows: controlling the total content of FeO and MnO in percentage by weight in the slag to be 1.2% and the alkalinity of the slag to be 5.4; adding rare earth alloy 10min before VD refining, wherein the content of O in the rare earth alloy is 0.013 wt%, meanwhile, the proportion of rare earth elements in the alloy is 98%, and the balance is mainly Fe; under the condition that the VD vacuum degree is less than or equal to 67Pa, the vacuum circulation is carried out for 10min, and the soft blowing time is 12min after the air is broken; and protective pouring is carried out during ladle casting, secondary oxidation is reduced, and the O content before and after casting is changed to 0.0001 wt%.
The rolling process sequentially comprises a first rolling and a second rolling, wherein in the first rolling, the initial rolling temperature is 1130 ℃, and the final rolling temperature is 1010 ℃. In the second rolling, the initial rolling temperature is 850 ℃, and the final rolling temperature is 785 ℃;
in the cooling process, the cooling process comprises two-stage cooling, wherein in the first-stage cooling, the start cooling temperature is 745 ℃, the end cooling temperature is 535 ℃, and the cooling rate is 27 ℃/s. In the second stage cooling, the start cooling temperature is 525 ℃, the end cooling temperature is 290 ℃, and the cooling rate is 16 ℃/s.
Comparative example 1
Comparative example 1 provides a pipeline steel whose chemical composition is shown in tables 1 and 2, and the balance being Fe and inevitable impurities.
TABLE 1
| Numbering | C/％ | Si/％ | Mn/％ | P/％ | S/％ | Alt/％ | Nb/％ | Ti/％ |
| Example 1 | 0.05 | 0.20 | 1.65 | 0.008 | 0.0012 | 0.035 | 0.075 | 0.015 |
| Example 2 | 0.07 | 0.25 | 1.70 | 0.007 | 0.0008 | 0.032 | 0.08 | 0.018 |
| Example 3 | 0.06 | 0.25 | 1.80 | 0.007 | 0.0008 | 0.032 | 0.06 | 0.018 |
| Example 4 | 0.06 | 0.25 | 1.80 | 0.007 | 0.0008 | 0.032 | 0.06 | 0.018 |
| Comparative example 1 | 0.06 | 0.25 | 1.80 | 0.007 | 0.0008 | 0.032 | / | / |
TABLE 2
| Numbering | Ni/％ | Cr/％ | (La+Ce)/％ | Y/％ | Mo/％ |
| Example 1 | 0.25 | 0.25 | 0.008 | / | 0.17 |
| Example 2 | 0.35 | 0.30 | 0.02 | / | 0.30 |
| Example 3 | 0.20 | 0.30 | 0.005 | / | 0.10 |
| Example 4 | 0.20 | 0.30 | / | 0.015 | 0.10 |
| Comparative example 1 | 0.20 | 0.30 | / | / | / |
TABLE 3
TABLE 4
TABLE 5
The line steels prepared in examples 1 to 4 and comparative example 1 were subjected to impact toughness tests by preparing line steels, and the impact toughness at-20 c is shown in table 5. After the pipeline steels prepared in examples 1-4 and comparative example 1 were submerged arc welded, the weld joint was tested for impact toughness and flaw detection in the macrocrystalline region and the weld line region, as shown in table 5. Meanwhile, the coarse crystal region and the weld line region of the welded joint are subjected to microstructure observation under an optical microscope, and the microstructure is observed under a scanning electron microscope, as shown in fig. 1-2.
The flaw detection qualification rate is that an ultrasonic flaw detector is adopted to carry out full-coverage scanning on a steel plate along the length direction, the minimum resolution of a probe is more than or equal to 2mm, at present, when the wavelength is more than or equal to 5mm, the welded joint is considered to be unqualified, and the qualification rate is obtained by dividing the number of the unqualified welded joints by the total detection number.
As can be seen from Table 5, the impact toughness of the base steel material for pipeline steel prepared in examples 1-4 at-20 ℃ is 358-384J, the impact toughness of the fusion line at-10 ℃ is 305-348J, and the impact toughness of the coarse crystal region at-10 ℃ is 318-342J. Comparative example 1 provides a base material of a steel for a pipeline having an impact toughness of 183J at-20 ℃, a weld line having an impact toughness of 103J at-10 ℃ and a coarse grain region having an impact toughness of 97J at-10 ℃ which are lower than those of examples 1 to 4 of the present invention.
The invention provides thick pipeline steel and a preparation method thereof, which adopt Nb, V and Ti to match with rare earth elements, on one hand, the thick pipeline steel can form rare earth inclusions in molten steel, and the rare earth inclusions are distributed in a fine dispersion mode, so that the cleanliness of the molten steel is improved, and the impact toughness of the pipeline steel can be improved; on the other hand, in the high-temperature welding process, the rare earth inclusions in the heat affected zone can induce acicular ferrite in the crystal to refine crystal grains, and can also refine the sizes of precipitates of Nb, V and Ti, so that the impact toughness of a coarse crystal zone and a fusion line is improved. After the pipeline steel provided by the invention is welded, the impact toughness of a base material at the temperature of minus 20 ℃ is 358-doped 384J, the impact toughness of a fusion line at the temperature of minus 10 ℃ is 305-doped 348J, the impact toughness of a coarse crystal area at the temperature of minus 10 ℃ is 318-doped 342J, and the toughness of the fusion line and the coarse crystal area is good.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. The thick-gauge pipeline steel is characterized by comprising the following chemical components in percentage by mass:
c: 0.04-0.07%, Si: 0.15-0.30%, Mn: 1.65-1.85%, P is less than or equal to 0.01%, S is less than or equal to 0.0020%, Alt: 0.03-0.05%, Nb: 0.07-0.09%, Ti: 0.010-0.020%, Ni: 0.25-0.35%, Cr: 0.2-0.35%, RE: 0.005-0.020%, Mo: 0.15-0.30%, and the balance of Fe and inevitable impurity elements, wherein Re is a rare earth element.
2. A thick gauge pipeline steel as claimed in claim 1, wherein Re is at least one of: la, Ce and Y.
3. A thick gauge pipeline steel as claimed in claim 1, wherein the pipeline steel has a thickness of 25-60 mm.
4. A thick gauge pipeline steel as claimed in claim 1, wherein the pipeline steel is any one of: x80 and X90.
5. A method of producing a thick gauge pipeline steel as claimed in any one of claims 1 to 4, which comprises,
smelting and continuously casting molten steel to obtain a plate blank; the slab comprises the following chemical components in percentage by mass: c: 0.03-0.05%, Si: 0.15-0.30%, Mn: 1.65-1.85%, P is less than or equal to 0.01%, S is less than or equal to 0.0020%, Alt: 0.03-0.05%, Nb: 0.07-0.09%, Ti: 0.010-0.020%, Ni: 0.25-0.35%, Cr: 0.2-0.35%, RE: 0.005-0.020%, Mo: 0.15-0.30%, and the balance of Fe and inevitable impurity elements, wherein Re is a rare earth element;
rolling and cooling the steel billet to obtain pipeline steel; the rolling comprises rough rolling and finish rolling, wherein the rough rolling starting temperature is 1080-1160 ℃, and the rough rolling finishing temperature is 980-1050 ℃; the finish rolling starting temperature is 840-870 ℃, and the finish rolling finishing temperature is 780-820 ℃.
6. The method for preparing thick gauge pipeline steel according to claim 5, wherein the cooling is two-stage cooling, and in the first stage cooling, the start cooling temperature is 740-760 ℃, and the end cooling temperature is 530-540 ℃; in the second stage of cooling, the start cooling temperature is 520-530 ℃, and the final cooling temperature is 280-320 ℃.
7. The method for preparing thick-gauge pipeline steel according to claim 5, wherein the cooling rate of the first-stage cooling is 25-30 ℃/s; the cooling rate of the second stage cooling is 15-20 ℃/s.
8. The method for preparing thick-gauge pipeline steel according to claim 5, wherein the smelting comprises VD refining, and rare earth alloy is added 5-10min before the VD refining is finished, so that the mass fraction of the rare earth elements is 0.005-0.020%; in the rare earth alloy, the mass fraction of O is less than 0.015 percent, and the mass fraction of rare earth elements is more than 80 percent; in the VD refining process, the molten steel is circulated for more than or equal to 5min under the condition that the vacuum degree is less than or equal to 67Pa, the soft blowing is carried out for more than or equal to 10min after the vacuum breaking, and the flow rate of the soft blowing is 1-2 Nl/min/ton of steel.
9. The method for preparing thick gauge pipeline steel according to claim 5, wherein the smelting further comprises converter steelmaking, the sum of the mass fractions of FeO and MnO in the slag is controlled to be 0.5-2%, and the alkalinity of the slag is 3.5-6.0.
10. The method for preparing thick pipeline steel according to claim 5, wherein in the continuous casting process, protective casting is adopted, so that the change of the mass fraction of O in the molten steel before and after casting is less than 0.0002%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110168076.5A CN113046630B (en) | 2021-02-07 | 2021-02-07 | Thick pipeline steel and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110168076.5A CN113046630B (en) | 2021-02-07 | 2021-02-07 | Thick pipeline steel and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113046630A true CN113046630A (en) | 2021-06-29 |
| CN113046630B CN113046630B (en) | 2022-05-17 |
Family
ID=76508683
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110168076.5A Active CN113046630B (en) | 2021-02-07 | 2021-02-07 | Thick pipeline steel and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113046630B (en) |
Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003328080A (en) * | 2002-05-16 | 2003-11-19 | Nippon Steel Corp | High-strength steel pipe superior in low-temperature toughness and deformability, and method for manufacturing steel plate for steel pipe |
| CN101343715A (en) * | 2008-09-03 | 2009-01-14 | 天津钢管集团股份有限公司 | High-strength high-ductility X70 thick-wall seamless pipeline steel and manufacturing method |
| CN101376947A (en) * | 2007-08-28 | 2009-03-04 | 宝山钢铁股份有限公司 | High strength X90 pipeline steel and production method thereof |
| CN101845596A (en) * | 2009-03-24 | 2010-09-29 | 宝山钢铁股份有限公司 | Wide thick plate for X80 pipe line steel and manufacturing method thereof |
| CN101962733A (en) * | 2010-10-29 | 2011-02-02 | 北京科技大学 | Low-cost and high-toughness X80 pipe steel with high deformation resistance and manufacture method thereof |
| CN103233163A (en) * | 2013-05-02 | 2013-08-07 | 内蒙古科技大学 | X80 RE (rare-earth) pipeline steel containing RE Ce and manufacturing method thereof |
| CN103243278A (en) * | 2013-05-10 | 2013-08-14 | 武汉钢铁(集团)公司 | X90 pipeline steel and production method thereof |
| KR20140130325A (en) * | 2013-04-30 | 2014-11-10 | 현대제철 주식회사 | Hot-rolled steel sheet and method of manufacturing the same |
| CN104513932A (en) * | 2013-09-27 | 2015-04-15 | 无锡华冶钢铁有限公司 | High-strength pipeline steel plate and preparation method thereof |
| CN104805375A (en) * | 2015-04-02 | 2015-07-29 | 江阴兴澄特种钢铁有限公司 | Steel plate for super-thick high-tenacity X80 pipeline and manufacturing method of steel plate |
| CN109439846A (en) * | 2018-11-08 | 2019-03-08 | 包头钢铁（集团）有限责任公司 | A kind of low temperature resistant X80M pipe line steel of rare earth treatment and preparation method thereof |
| CN112126849A (en) * | 2020-08-21 | 2020-12-25 | 中国科学院金属研究所 | X90 pipeline steel with high strength and toughness and containing rare earth La and Ce elements and rolling method thereof |
-
2021
- 2021-02-07 CN CN202110168076.5A patent/CN113046630B/en active Active
Patent Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003328080A (en) * | 2002-05-16 | 2003-11-19 | Nippon Steel Corp | High-strength steel pipe superior in low-temperature toughness and deformability, and method for manufacturing steel plate for steel pipe |
| CN101376947A (en) * | 2007-08-28 | 2009-03-04 | 宝山钢铁股份有限公司 | High strength X90 pipeline steel and production method thereof |
| CN101343715A (en) * | 2008-09-03 | 2009-01-14 | 天津钢管集团股份有限公司 | High-strength high-ductility X70 thick-wall seamless pipeline steel and manufacturing method |
| CN101845596A (en) * | 2009-03-24 | 2010-09-29 | 宝山钢铁股份有限公司 | Wide thick plate for X80 pipe line steel and manufacturing method thereof |
| CN101962733A (en) * | 2010-10-29 | 2011-02-02 | 北京科技大学 | Low-cost and high-toughness X80 pipe steel with high deformation resistance and manufacture method thereof |
| KR20140130325A (en) * | 2013-04-30 | 2014-11-10 | 현대제철 주식회사 | Hot-rolled steel sheet and method of manufacturing the same |
| CN103233163A (en) * | 2013-05-02 | 2013-08-07 | 内蒙古科技大学 | X80 RE (rare-earth) pipeline steel containing RE Ce and manufacturing method thereof |
| CN103243278A (en) * | 2013-05-10 | 2013-08-14 | 武汉钢铁(集团)公司 | X90 pipeline steel and production method thereof |
| CN104513932A (en) * | 2013-09-27 | 2015-04-15 | 无锡华冶钢铁有限公司 | High-strength pipeline steel plate and preparation method thereof |
| CN104805375A (en) * | 2015-04-02 | 2015-07-29 | 江阴兴澄特种钢铁有限公司 | Steel plate for super-thick high-tenacity X80 pipeline and manufacturing method of steel plate |
| CN109439846A (en) * | 2018-11-08 | 2019-03-08 | 包头钢铁（集团）有限责任公司 | A kind of low temperature resistant X80M pipe line steel of rare earth treatment and preparation method thereof |
| CN112126849A (en) * | 2020-08-21 | 2020-12-25 | 中国科学院金属研究所 | X90 pipeline steel with high strength and toughness and containing rare earth La and Ce elements and rolling method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113046630B (en) | 2022-05-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5776860B1 (en) | Steel plates and line pipes for thick-walled high-strength line pipes with excellent sour resistance, crush resistance and low temperature toughness | |
| JP5292784B2 (en) | Welded steel pipe for high-strength line pipe excellent in low temperature toughness and method for producing the same | |
| JP5098235B2 (en) | High-strength steel pipe for line pipe excellent in low-temperature toughness, high-strength steel sheet for line pipe, and production method thereof | |
| JP5251092B2 (en) | Welded steel pipe for high-strength line pipe excellent in low temperature toughness and method for producing the same | |
| JP5251089B2 (en) | Welded steel pipe for high-strength thick-walled line pipe excellent in low-temperature toughness and manufacturing method | |
| JP6872616B2 (en) | Steel materials for pressure vessels with excellent hydrogen-induced cracking resistance and their manufacturing methods | |
| KR100868423B1 (en) | High strength api-x80 grade steels for spiral pipes with less strength changes and method for manufacturing the same | |
| JP7219882B6 (en) | Steel material for pressure vessel and its manufacturing method | |
| EP2799567A1 (en) | High strength steel pipe having excellent ductility and low temperature toughness, high strength steel sheet, and method for producing steel sheet | |
| WO2010052926A1 (en) | Method for manufacturing steel plate and steel pipe for ultrahigh-strength line pipe | |
| US10081042B2 (en) | Electric resistance welded steel pipe excellent in weld zone and method of production of same | |
| JP6763141B2 (en) | Manufacturing method of steel plate for LPG tank | |
| CN108359900A (en) | A kind of low production method for being mingled with pipe line steel of high intensity | |
| WO2010052927A1 (en) | Method for manufacturing steel plate and steel pipe for ultrahigh-strength line pipe | |
| KR20110098929A (en) | Method of manufacturing sheet steel for thick-walled sour-resistant line pipe of excellent toughness | |
| JPH07173536A (en) | Production of steel sheet for high strength line pipe excellent in sour resistance | |
| CN108559907A (en) | A kind of low field trash pipe line steel production method | |
| EP2093302B1 (en) | Weld steel pipe with excellent low-temperature toughness for high-strength line pipe and process for producing the same | |
| JP2019534382A (en) | Cold-rolled steel sheet for flux-cored wire and manufacturing method thereof | |
| JP7155703B2 (en) | Thick steel plate for line pipe and manufacturing method thereof | |
| JP2004099930A (en) | High-strength welded steel pipe having excellent toughness of weld zone, and method for manufacturing the same | |
| JP2019056145A (en) | High tensile strength thick steel plate and method of producing the same | |
| CN113046630B (en) | Thick pipeline steel and preparation method thereof | |
| JP6421638B2 (en) | Low-temperature H-section steel and its manufacturing method | |
| JP4116817B2 (en) | Manufacturing method of high strength steel pipes and steel sheets for steel pipes with excellent low temperature toughness and deformability |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |