CN102127680B - Production method of hot rolled steel coil for shipbuilding - Google Patents
Production method of hot rolled steel coil for shipbuilding Download PDFInfo
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- CN102127680B CN102127680B CN2011100412968A CN201110041296A CN102127680B CN 102127680 B CN102127680 B CN 102127680B CN 2011100412968 A CN2011100412968 A CN 2011100412968A CN 201110041296 A CN201110041296 A CN 201110041296A CN 102127680 B CN102127680 B CN 102127680B
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Abstract
The invention relates to a production method of hot rolled steel coil for shipbuilding. The method comprises the following steps of: (1) designing contents, preprocessing molten iron, then, smelting in a converter, switching nitrogen and argon and tapping to obtain molten iron; (2) continuously casting the molten iron to obtain a plate blank, controlling the molten iron amount to be 8-15t and the liquid level to be 200-350 mm when stopping casting a continuous casting tundish and wholly protecting and casting while the insertion depth of a long water opening is 300-400 mm; (3) heating the plate blank; and (4) finally, rolling and coiling the heated plate blank. The invention adopts a RPC (Relaxation-Precipitation-phase Control) and TMCP (Thermomechnical Control Process) rolling process, decreases the C and Mn contents by utilizing niobium microalloying treatment and decreases production cost. The D32-level hot rolled steel coil for shipbuilding has excellent plasticity and toughness, the extensibility is improved by over 8 percent, the welding performance of the material is improved and the favorable surface quality of a continuous casting blank is ensured.
Description
Technical field
The invention belongs to the coils of hot-rolled steel preparation field, particularly a kind of production method of hot rolled steel coil for ship building.
Background technology
C is high in each steel mill's composition of now production yield strength 345MPa level series coil of strip, and slab surface crack is many, and the Strength surplus amount is large, and plasticity and toughness are low.The Strength surplus amount is large, affects cold-forming property; Casting billet surface has the crackle probability can not directly fill greatly, is unfavorable for energy-saving and emission-reduction; C content is high, and welding property is poor; Mn content is high in the steel, and production cost is high, the product market competition ability; Any rolling technology is adopted in steel rolling, and the performance inconsistency scope of product is large, is unfavorable for user's use.
The investigation of Q345 series coil of strip production performance actual achievement
Table 1 Q345 Series Steel thickness, performance range cartogram
As can be seen from Table 1:
Q345 produces main thickness below 16mm, and yield strength is at 290～540MPa, and tensile strength is at 450～665MPa, unit elongation 9.5～50%; The performance inconsistency scope is large aborning, the performance inconsistency lattice that have simultaneously.
Table 2 Q345 Series Steel thickness and performance index frequency table
As can be seen from Table 2:
The yield strength of Q345 mainly be in 370～490MPa, tensile strength mainly at 490～630MPa scope, unit elongation mainly 14～34%, to produce main thickness be 3-17mm;
Q345 series coil of strip produces a minute actual achievement investigation
625 stove Q345 are carried out C, Si, Mn element statistics.
Table 3 Q345 Series Steel C, Si, Mn content range cartogram
As can be seen from Table 3:
Q345 steel C average content is 0.16%, the Mn average content is 1.39%;
Table 4C, Si, the Mn composition frequency
As can be seen from Table 4:
Q345 Series Steel heat analysis C content is main 0.15～0.18%, Mn content is mainly 1.32～1.52%.
National standard (GB712) is to Q345 composition, performance requriements and the contrast of production actual achievement
Table 5 composition, performance requriements and production actual achievement
As can be seen from Table 5: the rich amount of coils of hot-rolled steel Q345 intensity is large, and unit elongation is low, and the material over-all properties is poor, and Mn is high in the composition.
Summary of the invention
Technical problem to be solved by this invention provides a kind of production method of hot rolled steel coil for ship building, the method has reduced C in the D32 composition of steel, Mn content, adopt suitable rolling technology and cooling control technology, improve the over-all properties of D32 steel, produce low-cost, high performance D32 coils of hot-rolled steel, in line with the theory realization energy-saving and emission-reduction of green iron and steel.
The production method of a kind of hot rolled steel coil for ship building of the present invention comprises:
1) Composition Design good after, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, the molten steel of tapping to get; Re-blow≤1 time tapping time 4.5～8.0min before the tapping; Add alloy before the tapping 4/5; The two pushing off the slag of tapping, the slag that arrives at a station is thick≤80mm; The omnidistance time 17～30min of Argon is processed at the argon station;
2) molten steel after the above-mentioned tapping is carried out continuous casting and gets slab, wherein connect water unwrap when watering in the first stove in the water yield 25～30t of Baogang, liquid level 550～580mm; Baogang's water yield 15～20t in during middle bag quick change, liquid level 350～400mm; Normally water the water yield 42～50t of Baogang in time cast maintenance, liquid level 950～1000mm; Change the large Bao Shizhong water yield 35～40t of Baogang, liquid level 800～850mm; Baogang's water yield is controlled at 8～15t, liquid level 200～350mm in when bag stops watering in the continuous casting; The whole process protection cast, long nozzle depth of penetration 300～400mm;
3) with above-mentioned heating of plate blank, 3mm≤slab thickness≤16mm, tapping temperature is controlled at 1230 ± 30 ℃, time inside furnace 160～200min, soaking time 22～30min;
4) with the slab rolling after the above-mentioned heating, the curling coils of hot-rolled steel that namely gets; 3mm≤slab thickness≤16mm, finish rolling temperature in are controlled at 1050 ± 30 ℃, and finishing temperature is controlled at 850 ± 30 ℃, and curling temperature is controlled to be 580 ± 30 ℃, and cooling strategy is back segment.
Above-mentioned steps 1) in, blows Ar time 5～8min, its bright circle≤200mm a little less than the ladle before steel treatment finishes in the converter smelting; Reinforced adjusting component and temperature in the converter smelting, ladle blows Ar time 5～8min, its bright circle≤200mm; The Argon processing finishes to unwrap the time of watering 10～13min to continuous casting steel.
Above-mentioned steps 1) weight percent of each composition of molten steel of tapping is as shown in table 6 in:
Table 6 ingredient standard
Above-mentioned steps 2) in, liquidus temperature is controlled to be 1526 ℃ during continuous casting, and the bag temperature is controlled to be 1551 ± 7 ℃ in the target, and crystallizer protecting residue adopts low-carbon steel protecting slag.
Above-mentioned steps 4) in, the gained coils of hot-rolled steel is D32 level hot rolled steel coil for ship building.
D32 level coils of hot-rolled steel of the present invention utilizes little niobium to process, and the content of decrease C, Mn is aided with suitable rolling technology and guarantees that coil of strip has good plasticity and toughness, and its unit elongation improves more than 8%, and-20 ℃ of ballistic works are enhanced about more than once; Low-carbon (LC) Composition Design (C≤0.08%) has improved the material welding property, guarantees surface quality of continuously cast slab good (in inferior peritectoid scope, casting billet surface produces a large amount of crackles with composition of steel in traditional D32 level shipbuilding), realizes simultaneously straight dress, energy-saving and emission-reduction; Low Mn design reduces the alloy consumption, reduces production costs.
Rolling technology adopts TMCP+RPC technique, will roll first rear relaxation-control phase transformation technique (RPC) technology and be applied to the production of (P+F) steel, and low finishing temperature and curling temperature guarantee coil of strip fine microstructures, even; Coil of strip has kept the microstructure characteristic of P+F, and coil of strip performance anisotropy is little; The D32 level steel of low C, low Mn composition has good combination of strength and toughness.This Composition Design and rolling technology will be that China is low-cost, a kind of new production method of high-performance low-alloy coils of hot-rolled steel.
Beneficial effect
1, the inventive method is simple, adopts the TMCP+RPC rolling technology, utilizes little niobium to process to reduce the content of C, Mn on the Composition Design, reduces the consumption of alloy, reduces production costs.
2, D32 level hot rolled steel coil for ship building of the present invention has good plasticity and toughness, has improved cold-forming property, avoids the cracking during bending problem of gross distortion in the use of D32 level coil of strip, reduces quality objection; Improve the material welding property, guaranteed that simultaneously surface quality of continuously cast slab is good, realized directly dress, energy-saving and emission-reduction.
Description of drawings
Fig. 1 is metallographic structure (500 times of amplifications) behind the D32 level steel rolling of sample number into spectrum 1, and grain fineness number is 11 grades.
Fig. 2 is metallographic structure (500 times of amplifications) behind the D32 level steel rolling of sample number into spectrum 2, and grain fineness number is 10 grades.
Fig. 3 is metallographic structure (500 times of amplifications) behind the D32 level steel rolling of sample number into spectrum 3, and grain fineness number is 10 grades.
Embodiment
Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiment only to be used for explanation the present invention and be not used in and limit the scope of the invention.Should be understood that in addition those skilled in the art can make various changes or modifications the present invention after the content of having read the present invention's instruction, these equivalent form of values fall within the application's appended claims limited range equally.
Embodiment 1
1) Composition Design good after, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, the molten steel of tapping to get; Re-blow tapping time 4.5min before the tapping 1 time; Add alloy before the tapping 4/5; The two pushing off the slag of tapping, the thick 80mm of the slag that arrives at a station; The omnidistance time 17min of Argon is processed at the argon station;
2) weight percent of each composition of molten steel after the above-mentioned tapping is followed successively by: C 0.06%, and Si 0.20%, and Mn 0.90%, P0.010%, and S 0.005%, and Nb+Ti+V 0.040%, and Als 0.020%, and all the other are iron and inevitable impurity; Described molten steel is carried out continuous casting gets slab, wherein connect water unwrap when watering in the first stove in the water yield 25t of Baogang, liquid level 550mm; Baogang's water yield 15t in during middle bag quick change, liquid level 350mm; Normally water time cast keep in the water yield 42t of Baogang, liquid level 950mm changes the large Bao Shizhong water yield 35t of Baogang, liquid level 800mm, when bag stops watering in the continuous casting in Baogang's water yield be controlled at 8t, liquid level 200mm; The whole process protection cast, long nozzle depth of penetration 300mm;
3) with above-mentioned heating of plate blank, time inside furnace 160min, soaking time 22min, slab thickness 3.55mm, tapping temperature is controlled at 1260 ℃;
4) with the slab rolling after the above-mentioned heating, the finish rolling temperature in is controlled at 1080 ℃, and finishing temperature is controlled at 880 ℃; Curling temperature is controlled to be 610 ℃, and cooling strategy is back segment, and the last curling sample number into spectrum that namely gets is 1 D32 level hot rolled steel coil for ship building.Accompanying drawing 1 is seen in its metallographic structure, and the tensile property assay sees Table 7, impacts assay and sees Table 8.
Embodiment 2
1) Composition Design good after, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, the molten steel of tapping to get; Re-blow tapping time 6.0min before the tapping 0 time; Add alloy before the tapping 4/5; The two pushing off the slag of tapping, the thick 60mm of the slag that arrives at a station; The omnidistance time 25min of Argon is processed at the argon station;
2) weight percent of each composition of molten steel after the above-mentioned tapping is followed successively by: C 0.07%, and Si 0.25%, and Mn 1.0%, P0.015%, and S 0.010%, and Nb+Ti+V 0.050%, and Als 0.025%, and all the other are iron and inevitable impurity; Described molten steel is carried out continuous casting gets slab, wherein connect water unwrap when watering in the first stove in the water yield 30t of Baogang, liquid level 560mm; Baogang's water yield 18t in during middle bag quick change, liquid level 380mm; Normally water time cast keep in the water yield 45t of Baogang, liquid level 980mm changes the large Bao Shizhong water yield 38t of Baogang, liquid level 830mm, when bag stops watering in the continuous casting in Baogang's water yield be controlled at 10t, liquid level 270mm; The whole process protection cast, long nozzle depth of penetration 350mm;
3) with above-mentioned heating of plate blank, time inside furnace 180min, soaking time 25min, slab thickness 7.05mm, tapping temperature is controlled at 1230 ℃;
4) with the slab rolling after the above-mentioned heating, the finish rolling temperature in is controlled at 1050 ℃, and finishing temperature is controlled at 850 ℃; Curling temperature is controlled to be 580 ℃, and cooling strategy is back segment, and the last curling sample number into spectrum that namely gets is 2 D32 level hot rolled steel coil for ship building.Accompanying drawing 2 is seen in its metallographic structure, and the tensile property assay sees Table 7, impacts assay and sees Table 8.
Embodiment 3
1) Composition Design good after, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, the molten steel of tapping to get; Re-blow tapping time 8.0min before the tapping 1 time; Add alloy before the tapping 4/5; The two pushing off the slag of tapping, the thick 30mm of the slag that arrives at a station; The omnidistance time 30min of Argon is processed at the argon station;
2) weight percent of each composition of molten steel after the above-mentioned tapping is followed successively by: C 0.08%, and Si 0.30%, and Mn 1.10%, P0.020%, and S 0.015%, and Nb+Ti+V 0.062%, and Als 0.030%, and all the other are iron and inevitable impurity; Described molten steel is carried out continuous casting gets slab, wherein connect water unwrap when watering in the first stove in the water yield 28t of Baogang, liquid level 580mm; Baogang's water yield 20t in during middle bag quick change, liquid level 400mm; Normally water time cast keep in the water yield 50t of Baogang, liquid level 1000mm changes the large Bao Shizhong water yield 40t of Baogang, liquid level 850mm, when bag stops watering in the continuous casting in Baogang's water yield be controlled at 15t, liquid level 350mm; The whole process protection cast, long nozzle depth of penetration 400mm;
3) with above-mentioned heating of plate blank, time inside furnace 200min, soaking time 30min, during slab thickness 10.55mm, tapping temperature is controlled at 1200 ℃;
4) with the slab rolling after the above-mentioned heating, the finish rolling temperature in is controlled at 1020 ℃, and finishing temperature is controlled at 820 ℃; Curling temperature is controlled to be 550 ℃, and cooling strategy is back segment, and the last curling sample number into spectrum that namely gets is 3 D32 level hot rolled steel coil for ship building.Accompanying drawing 3 is seen in its metallographic structure, and the tensile property assay sees Table 7, impacts assay and sees Table 8.
Tensile property assay of the present invention and impact that assay sees Table respectively 7, table 8.
Table 7 tensile property assay
Table 8 impacts assay
Claims (2)
1. the production method of a hot rolled steel coil for ship building comprises:
1) Composition Design good after, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, the molten steel of tapping to get; Re-blow≤1 time tapping time 4.5～8.0min before the tapping; Add alloy before the tapping 4/5; The two pushing off the slag of tapping, the slag that arrives at a station is thick≤80mm; The omnidistance time 17～30min of Argon is processed at the argon station; Wherein the weight percent of each composition of gained molten steel is followed successively by: C0.06～0.08%, and Si 0.20～0.30%, and Mn 0.90～1.10%, P≤0.020%, S≤0.015%, Nb+Ti+V≤0.062%, Als 0.020～0.030%, and all the other are iron and inevitable impurity;
2) molten steel after the above-mentioned tapping is carried out continuous casting and gets slab, wherein connect water unwrap when watering in the first stove in the water yield 25～30t of Baogang, liquid level 550～580mm; Baogang's water yield 15～20t in during middle bag quick change, liquid level 350～400mm; Normally water the water yield 42～50t of Baogang in time cast maintenance, liquid level 950～1000mm; Change the large Bao Shizhong water yield 35～40t of Baogang, liquid level 800～850mm; Baogang's water yield is controlled at 8～15t, liquid level 200～350mm in when bag stops watering in the continuous casting; The whole process protection cast, long nozzle depth of penetration 300～400mm;
3) with above-mentioned heating of plate blank, 3mm≤slab thickness≤16mm, tapping temperature is controlled at 1230 ± 30 ℃, time inside furnace 160～200min, soaking time 22～30min;
4) with the slab rolling after the above-mentioned heating, the curling coils of hot-rolled steel that namely gets; 3mm≤slab thickness≤16mm, finish rolling temperature in are controlled at 1050 ± 30 ℃, and finishing temperature is controlled at 850 ± 30 ℃, and curling temperature is controlled to be 580 ± 30 ℃, and cooling strategy is back segment;
Blow Ar time 5～8min, its bright circle≤200mm a little less than the ladle before steel treatment finishes in the described step 1) converter smelting; Reinforced adjusting component and temperature in the converter smelting, ladle blows Ar time 5～8min, its bright circle≤200mm; The Argon processing finishes to unwrap the time of watering 10～13min to continuous casting steel;
Described step 2) in, liquidus temperature is controlled to be 1526 ℃ during continuous casting, and middle bag temperature is controlled to be 1551 ± 7 ℃, and crystallizer protecting residue adopts low-carbon steel protecting slag.
2. the production method of a kind of hot rolled steel coil for ship building according to claim 1, it is characterized in that: the weight percent of each composition of molten steel of tapping in the described step 1) is followed successively by: C 0.07%, Si 0.25%, Mn 1.0%, P≤0.015%, S≤0.010%, Nb+Ti+V≤0.062%, Als 0.025%, and all the other are iron and inevitable impurity.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101254527A (en) * | 2008-02-01 | 2008-09-03 | 湖南华菱涟源钢铁有限公司 | Method for producing low-carbon bainite high-strength steel based on thin slab continuous casting and rolling process |
| CN101549364A (en) * | 2009-05-15 | 2009-10-07 | 首钢总公司 | Method of using hot tandem rolling broad strip mill to produce steel plate for ship hull structure use |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101254527A (en) * | 2008-02-01 | 2008-09-03 | 湖南华菱涟源钢铁有限公司 | Method for producing low-carbon bainite high-strength steel based on thin slab continuous casting and rolling process |
| CN101549364A (en) * | 2009-05-15 | 2009-10-07 | 首钢总公司 | Method of using hot tandem rolling broad strip mill to produce steel plate for ship hull structure use |
Non-Patent Citations (2)
| Title |
|---|
| 乔世奇.B级船体结构用热轧钢带的生产实践.《2010年全国炼钢-连铸生产技术会议论文集》.2010,332-337. * |
| 张本亮等.宁钢生产集装箱用钢B480GNQR 工艺技术研究.《第十六届全国炼钢学术会议论文集》.2010,514-518. * |
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