CN115418442A - Method for reducing titanium in LF (ladle furnace) smelting - Google Patents
Method for reducing titanium in LF (ladle furnace) smelting Download PDFInfo
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- CN115418442A CN115418442A CN202211050684.7A CN202211050684A CN115418442A CN 115418442 A CN115418442 A CN 115418442A CN 202211050684 A CN202211050684 A CN 202211050684A CN 115418442 A CN115418442 A CN 115418442A
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- 239000010936 titanium Substances 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000003723 Smelting Methods 0.000 title claims abstract description 22
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 title claims abstract description 11
- 229910052719 titanium Inorganic materials 0.000 title claims abstract description 11
- 238000009847 ladle furnace Methods 0.000 title abstract description 19
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 86
- 239000010959 steel Substances 0.000 claims abstract description 86
- 238000005096 rolling process Methods 0.000 claims abstract description 53
- 238000004519 manufacturing process Methods 0.000 claims abstract description 22
- 238000009749 continuous casting Methods 0.000 claims abstract description 19
- 239000002893 slag Substances 0.000 claims description 59
- 210000003128 head Anatomy 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 5
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 238000003780 insertion Methods 0.000 claims description 3
- 230000037431 insertion Effects 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 22
- 238000005507 spraying Methods 0.000 description 13
- 239000000047 product Substances 0.000 description 12
- 238000005266 casting Methods 0.000 description 10
- 238000001816 cooling Methods 0.000 description 10
- 229910052742 iron Inorganic materials 0.000 description 10
- 239000002253 acid Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 239000013078 crystal Substances 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 5
- 239000011572 manganese Substances 0.000 description 5
- 238000005554 pickling Methods 0.000 description 5
- 239000007921 spray Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005098 hot rolling Methods 0.000 description 4
- 238000005097 cold rolling Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000009628 steelmaking Methods 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000010583 slow cooling Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 230000035882 stress Effects 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- 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
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/076—Use of slags or fluxes as treating agents
-
- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
-
- 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
-
- 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
- Y02P10/25—Process efficiency
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Metal Rolling (AREA)
Abstract
The invention discloses a method for reducing titanium in LF (ladle furnace) smelting, belonging to the technical field of steel, wherein the LF smelting adopts early-stage slagging-off and slagging operation. Compared with the prior art, the molten steel obtained after the LF furnace is smelted meets the requirement that Ti is less than 0.0020 percent, and meets the requirement of producing the shallow stamping DC 01-grade steel in a hot-to-cold mode based on a continuous casting and rolling production line.
Description
Technical Field
The invention relates to a divisional application of a shallow stamping grade DC01 grade steel production method (application number CN 202111278462.6), relates to the technical field of steel and iron, and particularly relates to a titanium reduction method for LF furnace smelting.
Background
In recent years, a short-flow production line has the advantages of being green, environment-friendly and low in cost, and because the thin specification produced by the continuous casting and rolling production line has inherent advantages, various enterprises immediately go up to the production line. The low-carbon cold-formed steel is a mainstream product of a continuous casting and rolling production line, the yield strength of a finished product is 280MPa, the tensile strength is 390MPa, the elongation is about 36%, and the low-carbon cold-formed steel can be used as a product which is formed simply, such as a pipe, a bent piece, a cabinet body and the like. However, the low-carbon mild steel produced by a short-process production line has high limited dislocation density and poor anisotropy under a large compression ratio, and the strengthening effect of nano-scale precipitation is too large, so that the problems of high strength, low extension and incapability of stably manufacturing shallow stamping products are not solved well.
Disclosure of Invention
The technical task of the invention is to provide a production method of the shallow stamping grade DC01 steel aiming at the defects of the prior art, so as to overcome the defects that the thin product of the current continuous casting and rolling production line has high strength and can not meet the requirements of shallow stamping forming.
The technical scheme for solving the technical problem is as follows: a method for reducing titanium in LF smelting is characterized by comprising the following steps: the LF furnace smelting adopts the operation of early-stage slagging-off and re-slagging, and the slagging-off step comprises the following steps:
(1) After the ladle is hoisted to the LF furnace treatment position, the ladle is moved in an inclined mode until the steel slag at the mouth of the ladle can be seen by naked eyes of an operator, and then the inclined movement is stopped;
(2) Then the steel ladle is moved backwards in an inclined way for 3-5 degrees and is used as the initial position for slagging off, so that the height between the liquid level of the molten steel and the edge of the steel ladle can be basically fixed to form a standard height;
(3) Adopting a slag skimmer to skim, moving the slag skimmer to the position opposite to the ladle opening of the ladle, and inserting the slag skimmer below the liquid level of the molten steel to an insertion depth of 50-100 mm;
(4) And moving the slag raking device, gathering the steel slag in the steel ladle into a pile, continuously moving the slag raking device, moving the gathered and piled steel slag to the opening of the steel ladle, standing for 1-2 seconds at the opening, slightly lifting the slag raking device by 100-150 mm, raking the steel slag out of the opening of the steel ladle, and moving the steel slag to a specified slag tank to finish slag raking.
Furthermore, the thickness of the slag removing head of the slag remover is 20-25 mm, and the radian of the slag removing head is 10-15 degrees.
The molten steel obtained after LF smelting meets the requirement that Ti is less than 0.0020 percent.
The method is used for producing the steel for the shallow stamping grade DC01 grade.
And further, the method is used for producing the DC 01-grade steel with the shallow stamping grade based on a continuous casting and rolling production line in a hot-to-cold-replacing mode.
Further, the steel grade comprises the following chemical components: c:0.005-0.050%, si:0.01-0.06%, mn:0.05-0.15%, S: less than or equal to 0.012 percent, P: less than or equal to 0.020%, alt less than or equal to 0.050%, ti less than 0.0020%, B:0.0010-0.0025%, gas N is controlled below 45ppm, and the balance is Fe.
Compared with the prior art, the invention has the following outstanding beneficial effects:
1. the invention reduces the content of residual strengthening elements, particularly Ti elements, by high-cleanliness smelting in steel making, properly adds B elements for promoting the coarseness of crystal grains, and realizes the production of shallow stamping DC01 grade by high-temperature final rolling and high-temperature coiling;
2. can effectively reduce the strength of the ultrathin cold-formed plate produced by the continuous casting and rolling production line, reduce the anisotropy, meet the market demand, replace the cold rolling DC01 product, realize the replacement of cold with heat, and reduce the cost of the whole process
3. Compared with the prior art, the yield strength is reduced to about 230MPa from 290MPa, the tensile strength is reduced to about 350MPa from 390MPa, the elongation is improved to more than 38 percent from 34 percent, the performance is obviously improved, and the cold rolling grade DC01 product can be replaced.
Detailed Description
The present invention will be further described with reference to the following embodiments. Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.
The invention relates to a method for producing a shallow stamping grade DC01 steel by a hot-to-cold mode based on a continuous casting and rolling production line.
The steel of the invention comprises the following chemical components: c:0.005-0.050%, si:0.01-0.06%, mn:0.05-0.15%, S: less than or equal to 0.012 percent, P: less than or equal to 0.020%, alt less than or equal to 0.050%, ti less than 0.0020%, B:0.0010-0.0025%, gas N is controlled below 45ppm, and the balance is Fe.
Wherein, C is an important element for improving the strength of the material and reducing the elongation, the C content is not too high from the viewpoints of avoiding a crystal covering region and reducing the strength, and the cost is considered, so the mass percent of C is controlled to be 0.005-0.050%.
Si has a good deoxidizing effect, but too high Si reduces the formability and weldability of the steel. Meanwhile, the iron sheet can be prevented from being pressed in at high temperature by proper Si content, and the Si content is properly added, so that the proportion of Si in the raw material is controlled to be 0.01-0.06%.
Mn can improve the strength of steel, weaken and eliminate the adverse effect of sulfur, but too high Mn can coarsen crystal grains and improve the strength, so that the proportion of Mn in the raw material is controlled to be 0.05-0.15%.
Al reduces the strength of the strip steel while inhibiting the aging of the low-carbon steel, so the proportion of Alt in the raw materials is properly controlled to be 0.025-0.035%.
B and N form coarse BN particles, limited precipitation in high-temperature austenite obviously inhibits fine AlN precipitation, weakens the pinning effect of the AlN particles in grain boundaries, inhibits ferrite nucleation, coarsens crystal grains and reduces strength. Meanwhile, the casting stability of the thin slab caster is considered, and the content of B is properly added, so that the content of B is controlled to be 0.0010-0.0025%.
Ti is a strong carbide forming element, the temperature of a non-recrystallization area is increased, and crystal grains are refined. When the steel grade is produced, the steel-making process ensures the purity, thereby controlling and reducing the Ti content to the maximum extent, wherein the Ti content is less than 0.0020 percent,
the solid solution strengthening strength can be reduced by controlling the free N content, and the N content is controlled to be below 45ppm by combining the B content and the Al content.
The process comprises the following steps: smelting → continuous casting → rough rolling → IH furnace heating → finish rolling → cooling → coiling to obtain hot rolled material.
S1, smelting
Smelting in a converter, an RH furnace and an LF furnace according to the chemical component proportion of the steel grade.
Wherein, the LF furnace smelting adopts the operation of early-stage slag skimming and re-slagging:
(1) After the steel ladle is hoisted to the LF furnace treatment position, the steel ladle is moved in an inclined mode until the steel slag at the mouth of the steel ladle can be seen by naked eyes of an operator, and then the inclined movement is stopped;
(2) Then the steel ladle is moved back to incline 3-5 degrees and is used as the initial position for slag skimming, so that the height of the liquid level of the molten steel and the edge of the steel ladle can be basically fixed to form a standard height;
(3) Removing slag by adopting a quick slag remover, moving the slag remover to the position opposite to the ladle opening of the ladle, and inserting the slag remover below the liquid level of molten steel to an insertion depth of 50-100 mm; wherein the slag remover is made of a Q355B steel plate, the thickness of the slag remover head is 20-25 mm, and the radian of the slag remover head is 10-15 degrees;
(4) And moving the slag raking device, gathering the steel slag in the steel ladle into a pile, continuously moving the slag raking device, moving the gathered and piled steel slag to the opening of the steel ladle, standing for 1-2 seconds at the opening, slightly lifting the slag raking device by 100-150 mm, raking the steel slag out of the opening of the steel ladle, and moving the steel slag to a specified slag tank to finish slag raking.
The sources of Ti in the DC01 grade steel are mainly residual Ti in steel and Ti brought by converter slag. When the residual Ti in the steel is low, the refining mainly reduces and increases Ti in the slag, when the residual Ti is high, the residual Ti in the molten steel is increased mainly, the whole refining process is a process that the Ti among the steel slag gradually reaches reaction balance, and the LF early-stage slag skimming and slagging operation is adopted, so that the content of Ti in the slag can be reduced, the Ti in the steel flows into the slag, the content of Ti in the steel is reduced, and the requirement that the Ti is less than 0.0020 percent is met.
S2, continuous casting
Continuously casting the molten steel treated by the LF furnace, wherein the thickness of a casting blank at the outlet of a continuous casting machine is 70-110mm,
s3, hot rolling
(1) Rough rolling:
the rough rolling inlet temperature is 960-1010 ℃, and the rough rolling outlet temperature is 950-1010 ℃.
The thickness of the intermediate blank is 7.5-18 mm, and different intermediate blank thicknesses are set according to different thicknesses of finished products: the specification of 0.6-1.2mm, the thickness of the intermediate blank is 9-12 times of the target specification, the specification of 1.2-4mm, and the thickness of the intermediate blank is 4-8 times of the target specification. The setting of the thickness of the intermediate blank can reduce the dislocation strength of the finished product, reduce the mixed crystal tendency and reduce the anisotropy.
(2) Heating in an IH furnace:
the induction heating temperature is 1100-1150 ℃ to ensure the finish rolling temperature;
(3) Finish rolling:
the finish rolling temperature is 850-890 ℃, and the hot rolled strip steel with different thicknesses of 0.6-4.0mm is produced by finish rolling;
(4) Cooling, coiling and slow cooling
After the strip steel is cooled to 700-720 ℃, coiling and warehousing for slow cooling, and fully releasing the internal stress of the steel coil;
and cooling the finished product off line for 5 days, and then cooling the finished product to below 45 ℃.
(5) Acid pickling for flattening
And (3) slowly cooling the obtained steel coil to enter an acid leveling line, wherein the total elongation of the acid pickling process is 1.0-2.0%.
Due to the characteristics of low carbon, low silicon and low manganese in the molten steel, the yield strength and the tensile strength can be reduced, the elongation is improved, and the production of the shallow stamping grade DC01 grade steel is realized. However, as the deformation resistance of the strip steel is low, the scale is easy to press in, and the pickling failure rate is increased.
Therefore, in order to better realize the control of the iron scale, the hot rolling process of the invention is optimized and improved as follows:
(1) Primary temperature control adjustment
And (3) carrying out temperature reduction at the outlet of the continuous casting machine in a spraying mode, and controlling the temperature of the casting blank in a roughing mill to be 950-1000 ℃.
The specific hardware settings may be: a group of spraying devices are added at the outlet of the continuous casting machine, the spraying devices are arranged in an upper row and a lower row, the number of water nozzles is 11-21, and the spraying pressure is 10-25bar.
(2) Rough rolling
The temperature is reduced between R1/R2 and R2/R3 of the roughing mill, and the finishing temperature of the roughing mill is controlled to be 960-1000 ℃.
The specific hardware settings may be: a group of spray devices are respectively arranged between R1/R2 and R2/R3 of the roughing mill, the upper row and the lower row are provided, the number of water nozzles is 11-21, the spray pressure is 10-25bar, an operator can set the water quantity, the rough rolling outlet temperature is guaranteed to hit, the rolling temperature rise and the casting blank core return temperature are mainly inhibited, and the final rolling temperature of the roughing mill is reduced to 960-1000 ℃.
The spray device of the rough rolling area aims at controlling the rolling temperature entering each frame rolling mill of rough rolling, the outlet temperature of the rough rolling mill is not suitable to be too high so as to inhibit the generation of hard iron scales, reduce the generation and the press-in amount of the iron scales and control the press-in of the iron scales generated in the continuous casting machine.
(3) Secondary temperature control regulation
And carrying out multi-point temperature reduction at the outlet of the roughing mill and the drum shear, and controlling the temperature of the IH inlet to be 880-930 ℃.
The specific hardware settings may be: two rows of spraying devices are respectively added at the outlet of the roughing mill and the strand shearing position, the number of water nozzles is 11-21, the spraying pressure is 10-25bar, an operator can set the water quantity, the temperature of the IH inlet is adjusted in a small range, and the generation of iron oxide scales between the roughing mill and the IH furnace is mainly inhibited.
Because the casting blank core of the continuous rolling and continuous casting production line contains heat, the difference between the surface temperature and the core temperature of the casting blank is large, the core temperature is high, and the continuous rolling and continuous casting production line is different from the traditional hot continuous rolling and has a core temperature returning process, so that spray devices are added at an R3 outlet and a rotary drum shear to cool. Moreover, the water pressure is low (10-20 bar), and the traditional descaling (more than 100-250 bar) is not realized. The present invention aims to suppress the generation of scale, rather than to remove the scale with high pressure.
(4) IH furnace heating
The IH furnace heats to compensate for heat loss. Heating IH for 10 + -2 s from the temperature of 850-920 deg.C at IH inlet to 1060-1120 deg.C at IH outlet
(5) Single pass descaling
The pressure of the descaling system is controlled to be 340-380 bar.
(6) And three times of temperature control regulation
And carrying out multi-point temperature reduction at the inlet of the finishing mill, and controlling the finishing rolling start temperature to be 960-1030 ℃.
The specific hardware settings may be: two rows of spraying devices are arranged at the inlet of the finishing mill, and the two rows of spraying devices are opened by 60-100% at the inlet of the finishing mill during normal production.
(7) And finish rolling
And (3) performing finish rolling by five frames, performing multipoint temperature reduction between F1/F2 and F2/F3, and controlling the finish rolling temperature to be 850-890 ℃.
The specific hardware settings may be: two rows of spraying devices are arranged between the F1 and the F2, one row of spraying devices is arranged on the lower surface between the F2 and the F3, and the spraying pressure is 10-25bar. During normal production, 10-50% of two rows of spraying devices between F1/F2 are opened, 10-30% of one row of spraying devices on the lower surface between F2/F3 are opened, and the specific set water amount is reasonably used according to the condition of the finish rolling temperature.
The inlet temperature is controlled to be lower than that of the traditional hot continuous rolling through each stage of finish rolling spray device, and the temperature drop in the finish rolling process is small, so that the generation and the press-in amount of the iron scale are reduced, and the press-in of the iron scale generated in finish rolling can be controlled.
To better compare the formulations of the present application with the prior art, comparative tests were performed.
The chemical compositions (in weight%) of examples 1 to 4 and comparative examples 1 to 2 are shown in the following table, with gas N controlled to 45ppm or less, with the balance being iron and unavoidable impurities.
| Item | C | Si | Mn | P | S | Alt | Ti | B |
| Example 1 | 0.006 | 0.029 | 0.21 | 0.012 | 0.003 | 0.025 | 0.0011 | 0.0011 |
| Example 2 | 0.012 | 0.035 | 0.12 | 0.016 | 0.002 | 0.026 | 0.0019 | 0.0015 |
| Example 3 | 0.025 | 0.045 | 0.20 | 0.010 | 0.004 | 0.023 | 0.0014 | 0.0024 |
| Example 4 | 0.046 | 0.043 | 0.096 | 0.015 | 0.002 | 0.035 | 0.0018 | 0.0018 |
| Comparative example | 0.034 | 0.046 | 0.18 | 0.011 | 0.0015 | 0.034 | 0.0048 | 0 |
According to the requirements of the material component design, smelting by adopting a converter, an LF furnace and an RH furnace to obtain molten steel with required components; and continuously casting the molten steel under the protection of Ar blowing in the whole process to obtain a continuous casting slab with the thickness of 70-110 mm. And heating the casting blank, then sending the casting blank to a hot continuous rolling mill for rolling, controlling the rolling by a rough rolling and finish rolling continuous rolling mill set, cooling by laminar flow, then coiling, cooling by adopting a front section by adopting laminar flow, and producing a hot-rolled raw coil with the thickness of 0.6-4.0 mm.
The process flow routes of the examples 1 to 4 and the comparative example are as follows: steel making → continuous casting → rough rolling → finish rolling → laminar cooling → coiling, and obtaining the final product by acid cleaning and leveling in the later stage. All the steps are single-pass descaling before finish rolling, and the descaling pressure is 340bar respectively.
The hot rolling process of the embodiment 1-3 is an optimized scheme, and the rolling temperature of each rolling area is controlled through multi-point temperature reduction to inhibit the generation of surface scale. Example 4 is the basic scheme and the comparative example is the prior art scheme.
The main process control parameters for each hot rolling group are shown in the following table.
The scale indentation defect judgment ratio of each example and the comparative example is shown in the following table.
| Item | Thickness specification (mm) | Yield strength (MPa) | Tensile strength (MPa) | Elongation (%) | Acid pickling judging rate (%) |
| Example 1 | 0.6 | 248 | 362 | 38 | 0.14 |
| Example 2 | 0.8 | 243 | 352 | 38 | 0.12 |
| Example 3 | 1.2 | 236 | 349 | 39 | 0.09 |
| Example 4 | 1.5 | 228 | 342 | 41 | 0.69 |
| Comparative example | 1.5 | 293 | 396 | 34 | 0.32 |
From the data in the above table, the steel for the shallow stamping level DC01 obtained by using the component system and the process technology in the embodiments 1 to 4 can effectively reduce the strength of the ultrathin cold-formed plate produced by the continuous casting and rolling production line, the yield strength is reduced from 293MPa to 228-248 MPa, the tensile strength is reduced from 396MPa to 342-362 MPa, the elongation is increased from 34% to over 38%, the anisotropy is reduced, the market demand is met, the steel replaces the DC01 product in the cold rolling level, the hot cooling is used for replacing the cold cooling, and the cost of the whole process is reduced.
Compared between the groups of the embodiments, the embodiment 1-3 groups of the optimized technology have good iron scale control capability, the acid pickling judgment rate can be controlled within 0.15 percent even under the condition of high drawing speed of 4.5-5.2m/min of the steel feeding drawing speed of a rolling mill, the requirements of users are met, the thin-gauge rolling is stable, the temperature difference of the cross section is controlled within 30 ℃, and the deviation of a central line is +/-8 mm. In the group of example 4, spindle-shaped or dispersed Hu Jiaoyan scale pressing-in performance exists locally, no landscape-shaped scale pressing-in condition exists, and the acid washing rate is higher than that of the groups of examples 1 to 3.
While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes in the invention can be made therein without departing from the spirit and scope thereof.
Claims (6)
1. A method for reducing titanium in LF smelting is characterized by comprising the following steps: the LF furnace smelting adopts early-stage slagging-off and slagging-off operation, and the slagging-off step comprises the following steps:
(1) After the steel ladle is hoisted to the LF furnace treatment position, the steel ladle is moved in an inclined mode until the steel slag at the mouth of the steel ladle can be seen by naked eyes of an operator, and then the inclined movement is stopped;
(2) Then the steel ladle is moved back to incline 3-5 degrees and is used as the initial position for slag skimming, so that the height of the liquid level of the molten steel and the edge of the steel ladle can be basically fixed to form a standard height;
(3) Removing slag by using a slag remover, moving the slag remover to the position opposite to the ladle opening of the ladle, and inserting the slag remover below the liquid level of molten steel to an insertion depth of 50-100 mm;
(4) And moving the slag raking device, gathering the steel slag in the steel ladle into a pile, continuously moving the slag raking device, moving the gathered and piled steel slag to the opening of the steel ladle, standing for 1-2 seconds at the opening, slightly lifting the slag raking device by 100-150 mm, raking the steel slag out of the opening of the steel ladle, and moving the steel slag to a specified slag tank to finish slag raking.
2. The LF furnace smelting titanium reduction method according to claim 1, characterized by comprising the following steps: the thickness of the slag raking head of the slag raking device is 20-25 mm, and the radian of the slag raking head is 10-15 degrees.
3. The LF furnace smelting titanium reduction method according to claim 1, characterized by comprising the following steps: the molten steel obtained after LF smelting meets the requirement that Ti is less than 0.0020 percent.
4. The LF furnace smelting titanium reduction method according to claim 1, characterized by comprising the following steps: the method is used for producing the steel for the shallow stamping grade DC 01.
5. The LF furnace smelting titanium reduction method according to claim 4, characterized by comprising the following steps: and producing the shallow stamping grade DC01 grade steel based on a continuous casting and rolling production line in a hot-to-cold replacing mode.
6. The LF furnace smelting titanium reduction method according to claim 5, characterized by comprising the following steps: the steel grade comprises the following chemical components: c:0.005-0.050%, si:0.01-0.06%, mn:0.05-0.15%, S: less than or equal to 0.012 percent, P: less than or equal to 0.020%, alt less than or equal to 0.050%, ti less than 0.0020%, B:0.0010-0.0025%, gas N is controlled below 45ppm, and the balance is Fe.
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Denomination of invention: A method for reducing titanium in LF furnace smelting Effective date of registration: 20231215 Granted publication date: 20230609 Pledgee: Rizhao Bank Co.,Ltd. Pledgor: RIZHAO BAOHUA NEW MATERIAL CO.,LTD. Registration number: Y2023980072207 |
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