CN108531807B - Thick-wall large-caliber X80M pipeline clean steel and smelting method - Google Patents
Thick-wall large-caliber X80M pipeline clean steel and smelting method Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- 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
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
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- 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
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
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- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/10—Handling in a vacuum
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- C22C33/04—Making ferrous alloys by melting
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- 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
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- 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
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- 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
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- 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
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
Abstract
The invention discloses thick-wall large-caliber X80M pipeline clean steel and a smelting method, which relate to the technical field of metallurgy and comprise the following chemical components in percentage by mass: c: 0.04-0.06%, Si: 0.10-0.30%, Mn: 1.70-1.80%, P is less than or equal to 0.013%, S: 0.0010%, Nb: 0.060% -0.070%, Ti: 0.006% -0.020%, Ni: 0.20-0.30%, Cr: 0.10-0.20%, Cu: 0.10% -0.30%, Mo: 0.10-0.20%, Al: 0.015% -0.050%, Ca: 0.0005 to 0.0040 percent, and the balance of Fe and impurities. The invention provides a production process for effectively improving the smelting of clean steel of large-wall-thickness pipeline steel by changing the form of inclusions and promoting the floating mechanism of the inclusions in the static stirring and calming processes, and the qualification rate of 1.5-grade inclusions is stably improved to more than 99%.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to thick-wall large-caliber X80M pipeline clean steel and a smelting method.
Background
The high-grade pipeline steel X80M used in the current Russian line and medium petrochemical new gas pipeline project in the petroleum has extremely strict requirements on the purity of molten steel, the inclusion requirement A, B, C, D is 1.5 grade, the product requirement wall thickness is more than 30.8mm, the plate width is more than 3700mm, the blank is more than 300mm and the width is more than 2500mm, and the inclusion qualification rate is only about 88% by adopting the existing production process.
Disclosure of Invention
Aiming at the technical problems, the invention overcomes the defects of the prior art, provides the method for smelting the clean steel of the X80M pipeline with thick wall and large caliber, and stably improves the qualification rate of 1.5-grade inclusion to more than 99 percent.
In order to solve the technical problems, the invention provides thick-wall large-caliber X80M pipeline clean steel which comprises the following chemical components in percentage by mass: c: 0.04-0.06%, Si: 0.10-0.30%, Mn: 1.70-1.80%, P is less than or equal to 0.013%, S: 0.0010%, Nb: 0.060% -0.070%, Ti: 0.006% -0.020%, Ni: 0.20-0.30%, Cr: 0.10-0.20%, Cu: 0.10% -0.30%, Mo: 0.10-0.20%, Al: 0.015% -0.050%, Ca: 0.0005 to 0.0040 percent, and the balance of Fe and impurities.
The invention also aims to provide a method for smelting the thick-wall large-caliber X80M pipeline clean steel, which comprises the following steps:
s1, performing composite desulfurization by adopting lime and magnesium powder in the desulfurization station, removing slag after desulfurization, wherein S in molten iron entering a furnace is less than or equal to 0.0020%, and S after converter is less than or equal to 0.0010%;
s2, adopting a BOF → LF furnace refining → RH refining → continuous casting process route for steel making; the tapping temperature of the converter is 1660-1680 ℃; converter tapping adopts premelted refining slag and active lime for slagging;
s3, heating and slagging are carried out after the molten steel reaches the LF furnace, and the bottom blowing argon flow is 300 Nl/min-500 Nl/min in the heating and slagging process; properly adding aluminum wires according to the condition of furnace slag to achieve white slag and performing desulfurization after arc burying, wherein the adding amount of lime is 1Kg/t, the adding amount of the aluminum wires is 0.1Kg/t, the flow of bottom-blown argon is 250 Nl/min-350 Nl/min, feeding aluminum wires to adjust the aluminum content of molten steel, and controlling the flow of argon to be 20 Nl/min-30 Nl/min in the aluminum wire feeding process; alloying according to the components of the target steel grade, heating for 6-8 min, sampling and analyzing, and continuously heating and desulfurizing the lower electrode; after LF alloying, the sulfur content is stabilized within 0.0010%;
s4, RH meets the vacuum circulation condition that the vacuum degree is less than or equal to 3mbar for 15min to 20min, calcium treatment is carried out after the vacuum treatment is finished, a seamless calcium line is adopted for the calcium treatment, the treatment capacity of the calcium line is 150m to 180m, the calcium content after the treatment is 0.0015 percent to 0.0025 percent, and static stirring is carried out for 20min after the calcium treatment is finished;
and S5, CCM casting adopts full-protection casting, the ladle closing and the ladle changing are carried out according to the ladle allowance below 5t, and the superheat degree of the tundish meets 35-40 ℃.
The technical scheme of the invention is further defined as follows:
further, in step S3, the feeding amount of the aluminum wire is controlled by keeping the aluminum content in the molten steel in the smelting process within the range of 0.04-0.05%.
In the foregoing method for smelting clean steel for a thick-walled large-caliber X80M pipeline, in step S4, alloying of molten steel is strictly prohibited after vacuum treatment is started, and addition of a deoxidizer is strictly prohibited.
The thick-wall large-caliber X80M pipelineA clean steel smelting method comprises the following steps that in step S5, a tundish covering agent adopts a liquid covering agent, and the liquid covering agent comprises the following chemical components in percentage by mass: CaO: 20.0% -30.0%, MgO: 10.0-30.0% of Al2O3:15.0%～25.0%，SiO2:≤8.0%，CFixing device：≤1.0%，F：≤0.50%，R:4.0～6.0，H2O is less than or equal to 0.5 percent, and the balance is impurities.
The invention has the beneficial effects that:
(1) the invention provides a special component design and calcium treatment process, CaS-CaO solid inclusion is obtained after RH calcium treatment is finished, the contact angle and surface tension of the solid inclusion in molten steel are far larger than those of liquid inclusion, and the solid inclusion is more beneficial to aggregation, growth and floating in the molten steel;
(2) according to the invention, molten steel components with S less than or equal to 0.0010% are obtained after LF treatment, and molten steel with calcium content of 0.0015% -0.0025% is obtained after RH vacuum treatment, so that the modification of inclusions in the molten steel into CaS-CaO solid inclusions can be promoted;
(3) the method has the advantages that the obtained solid inclusions are a precondition, the aggregation, the growth and the floating of the inclusions need the molten steel to have good dynamic and thermodynamic conditions, the high-superheat-degree pouring effectively improves the thermodynamic conditions of the molten steel in the ladle in the processes of static stirring, transportation and pouring, the dynamic conditions are provided by argon blowing in the static stirring process and molten steel flowing in the pouring process, and the appropriate dynamic and thermodynamic conditions promote the solid inclusions in the molten steel to be effectively aggregated, grown and floated and removed;
(4) the superheat degree of the invention is in the range of 35-40 ℃, which is not only suitable for pouring molten steel, but also the thermodynamic condition of the molten steel completely satisfies the aggregation, growth, floating and removal of impurities, improves the purity of the molten steel, and improves the internal quality of the molten steel;
(5) in the invention, the addition of slag materials into the converter is beneficial to slag premelting, the time for making white slag by LF is shortened, and the LF desulfurization pressure is reduced;
(6) in the invention, the sulfur content after LF alloying is stabilized within 0.0010 percent, thus providing precondition for obtaining stable CaS-CaO solid inclusion after RH calcium treatment;
(7) in the invention, the allowance of the large ladle is set to be less than 5t, the large ladle is closed and the ladle is changed, so that the slag-free pouring of the medium ladle is ensured, the covering agent of the medium ladle adopts a liquid covering agent, the composition of the covering agent is closer to the composition of RH furnace slag, the adsorption effect on impurities is better, and the effective adsorption of the covering agent of the medium ladle on the impurities is ensured.
Detailed Description
Example 1
The method for smelting the thick-wall large-caliber X80M pipeline clean steel provided by the embodiment comprises the following steps:
s1, performing composite desulfurization by adopting lime and magnesium powder in the desulfurization station, removing slag after desulfurization, wherein S in molten iron entering a furnace is less than or equal to 0.0020%, and S after converter is less than or equal to 0.0010%;
s2, adopting a BOF → LF furnace refining → RH refining → continuous casting process route for steel making; the tapping temperature of the converter is 1660-1680 ℃; converter tapping adopts premelted refining slag and active lime for slagging;
s3, heating and slagging are carried out after the molten steel reaches the LF furnace, and the bottom blowing argon flow is 300 Nl/min-500 Nl/min in the heating and slagging process; properly adding aluminum wires according to the condition of furnace slag to achieve white slag and performing desulfurization operation after arc burying, wherein the adding amount of lime is 1Kg/t, the aluminum wires are 0.1Kg/t, the flow of bottom-blown argon is 250 Nl/min-350 Nl/min, feeding aluminum wires to adjust the aluminum content of molten steel, the feeding amount of the aluminum wires is controlled by keeping the aluminum content in the molten steel in the smelting process within the range of 0.04% -0.05%, and the flow of argon is controlled within the range of 20 Nl/min-30 Nl/min in the aluminum wire feeding process; alloying according to the components of the target steel grade, heating for 6-8 min, sampling and analyzing, and continuously heating and desulfurizing the lower electrode; after LF alloying, the sulfur content is stabilized within 0.0010%;
s4, RH meets the requirement that the vacuum circulation is carried out for 15 min-20 min under the vacuum degree of less than or equal to 3mbar, the alloying operation of the molten steel is strictly forbidden after the vacuum treatment is started, and the addition of a deoxidizer is strictly forbidden; after the vacuum treatment is finished, performing calcium treatment, wherein a seamless calcium line is adopted for the calcium treatment, the treatment capacity of the calcium line is 150-180 m, the calcium content after the treatment is 0.0015-0.0025%, and the calcium treatment is statically stirred for 20 min;
s5, CCM casting adopts full protection casting, the ladle is closed and the ladle is changed according to the ladle allowance below 5t, the tundish covering agent adopts liquid covering agent, and the liquid covering agent is chemicalThe components and the mass percentage are as follows: CaO: 20.0% -30.0%, MgO: 10.0-30.0% of Al2O3:15.0%～25.0%，SiO2:≤8.0%，CFixing device：≤1.0%，F：≤0.50%，R:4.0～6.0，H2O is less than or equal to 0.5 percent, and the balance is impurities; the degree of superheat of the tundish meets 35-40 ℃.
Examples 2 to 6
The thick-wall large-caliber X80M pipeline clean steel provided by the embodiments 2 to 6 is produced by the production method described in the embodiment 1, the chemical components and the mass percentage are shown in the table 1, the parameter control is shown in the table 2, and the test detection results are shown in the table 3:
TABLE 1
TABLE 2
TABLE 3
The invention designs a process route which is used for obtaining molten steel with the sulfur content of not more than 0.0010% after the LF furnace treatment is finished and the calcium content of 0.0015% -0.0025% after the RH vacuum treatment, and the steel making adopts BOF → LF furnace refining → RH refining → continuous casting; adding an aluminum deoxidizer to perform deoxidation alloying in the processes of converter tapping and LF refining, and sending molten steel to RH for vacuum treatment to remove gas and impurities; the method comprises the steps of obtaining uniform and fine CaS-CaO solid oxides through unique component design, adopting high-superheat-degree pouring in the continuous casting process to achieve the purposes of molten steel sedation and inclusion full floating, effectively improving molten steel cleanliness, and obtaining cleaner X80M-grade pipeline steel through changing inclusion forms and promoting the floating mechanism of the inclusions in the static stirring and sedation processes.
The method is simple and easy to operate, has obvious effect, is beneficial to large-scale industrial production, stably improves the qualification rate of the 1.5-grade inclusion to more than 99 percent, meets the requirement of the production of the wide and thick casting blank clean steel, and meets the product requirements of high-grade steel pipelines such as China's middle and Russian east lines, new gas pipelines and the like.
In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.
Claims (3)
1. A method for smelting thick-wall large-caliber X80M pipeline clean steel is characterized by comprising the following steps:
the chemical components and the mass percentage are as follows: c: 0.04-0.06%, Si: 0.10-0.30%, Mn: 1.70-1.80%, P is less than or equal to 0.013%, S: 0.0010%, Nb: 0.060% -0.070%, Ti: 0.006% -0.020%, Ni: 0.20-0.30%, Cr: 0.10-0.20%, Cu: 0.10% -0.30%, Mo: 0.10-0.20%, Al: 0.015% -0.050%, Ca: 0.0005 to 0.0040 percent of the total weight of the alloy, and the balance of Fe and impurities;
the method comprises the following steps:
s1, performing composite desulfurization by adopting lime and magnesium powder in the desulfurization station, removing slag after desulfurization, wherein S in molten iron entering a furnace is less than or equal to 0.0020%, and S after converter is less than or equal to 0.0010%;
s2, adopting a BOF → LF furnace refining → RH refining → continuous casting process route for steel making; the tapping temperature of the converter is 1660-1680 ℃; converter tapping adopts premelted refining slag and active lime for slagging;
s3, heating and slagging are carried out after the molten steel reaches the LF furnace, and the bottom blowing argon flow is 300 Nl/min-500 Nl/min in the heating and slagging process; properly adding aluminum wires according to the condition of furnace slag to achieve white slag and performing desulfurization after arc burying, wherein the adding amount of lime is 1Kg/t, the adding amount of the aluminum wires is 0.1Kg/t, the flow of bottom-blown argon is 250 Nl/min-350 Nl/min, feeding aluminum wires to adjust the aluminum content of molten steel, and controlling the flow of argon to be 20 Nl/min-30 Nl/min in the aluminum wire feeding process; alloying according to the components of the target steel grade, heating for 6-8 min, sampling and analyzing, and continuously heating and desulfurizing the lower electrode; after LF alloying, the sulfur content is stabilized within 0.0010%;
s4, RH meets the vacuum circulation condition that the vacuum degree is less than or equal to 3mbar for 15min to 20min, calcium treatment is carried out after the vacuum treatment is finished, a seamless calcium line is adopted for the calcium treatment, the treatment capacity of the calcium line is 150m to 180m, the calcium content after the treatment is 0.0015 percent to 0.0025 percent, and static stirring is carried out for 20min after the calcium treatment is finished;
s5, CCM casting adopts full-protection casting, the ladle closing and the ladle changing are carried out according to the ladle allowance below 5t, and the superheat degree of the tundish meets 35-40 ℃;
in step S5, the tundish covering agent is a liquid covering agent, and the liquid covering agent comprises the following chemical components in percentage by mass: CaO: 20.0% -30.0%, MgO: 10.0-30.0% of Al2O3:15.0%～25.0%，SiO2:≤8.0%，CFixing device：≤1.0%，F：≤0.50%，R:4.0～6.0，H2O is less than or equal to 0.5 percent, and the balance is impurities.
2. The method for smelting the thick-wall large-caliber X80M pipeline clean steel according to claim 1, wherein the method comprises the following steps: in the step S3, the feeding amount of the aluminum wire is controlled by keeping the aluminum content in the molten steel in the smelting process within the range of 0.04-0.05%.
3. The method for smelting the thick-wall large-caliber X80M pipeline clean steel according to claim 1, wherein the method comprises the following steps: in step S4, the alloying operation of the molten steel is strictly prohibited after the vacuum treatment is started, and the addition of a deoxidizer is strictly prohibited.
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| CN109234622B (en) * | 2018-09-29 | 2020-08-18 | 南京钢铁股份有限公司 | X80M deep-sea strain-resistant pipeline steel and smelting process |
| CN109321850A (en) * | 2018-11-07 | 2019-02-12 | 南京钢铁股份有限公司 | A kind of low grade of steel pipeline clean steel and smelting process |
| CN110016604A (en) * | 2019-05-07 | 2019-07-16 | 南京钢铁股份有限公司 | A kind of smelting process improving plate surface quality |
| CN113046655B (en) * | 2021-02-01 | 2022-06-17 | 南京钢铁股份有限公司 | Wide and thick pipeline steel with excellent low-temperature toughness and manufacturing method thereof |
| CN113278877A (en) * | 2021-02-01 | 2021-08-20 | 南京钢铁股份有限公司 | High-cleanliness pipeline steel and smelting method thereof |
| CN113046628B (en) * | 2021-02-01 | 2022-06-17 | 南京钢铁股份有限公司 | N800CF steel for pumped storage pressure steel pipe and smelting method |
| CN112981242B (en) * | 2021-02-01 | 2022-06-17 | 南京钢铁股份有限公司 | N800CF steel for pumped storage pressure steel pipe and manufacturing method thereof |
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