CN102127684B - Method for producing hot rolled steel coils - Google Patents
Method for producing hot rolled steel coils Download PDFInfo
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- CN102127684B CN102127684B CN2011100413138A CN201110041313A CN102127684B CN 102127684 B CN102127684 B CN 102127684B CN 2011100413138 A CN2011100413138 A CN 2011100413138A CN 201110041313 A CN201110041313 A CN 201110041313A CN 102127684 B CN102127684 B CN 102127684B
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Abstract
The invention relates to a method for producing hot rolled steel coils. The method comprises the following steps: 1) designing the components, pretreating molten iron, then carrying out converter smelting, carrying out nitrogen/argon changing over and carrying out tapping to obtain molten steel; 2) continuously casting the molten steel to obtain slabs, controlling the weight of the molten steel in the tundish to be 8-15t when casting of the continuous casting tundish is stopped, ensuring the liquid level to be 200-350mm; carrying out protective casting in the whole course and ensuring the insertion depth of the long nozzle to be 300-400mm; 3) heating the slabs; and 4) finally rolling and curling the heated slabs, thus obtaining the hot rolled steel coils. The method has the following beneficial effects: the contents of C and Mn in the Q235B steel components are reduced, proper rolling and cooling control processes are adopted, the comprehensive properties of the Q235B steel are improved and the produced Q235B hot rolled steel coils have low cost and high properties.
Description
Technical field
The invention belongs to the coil of strip preparation field, particularly a kind of working method of coils of hot-rolled steel.
Background technology
Existing ys 235MPa level Series Steel of producing is rolled into C height in the branch, and slab surface crack is many, and the intensity surplus capacity is big, and plasticity and toughness are low.The intensity surplus capacity is big, influences cold-forming property; Casting billet surface has the crackle probability can not directly adorn greatly, is unfavorable for energy-saving and emission-reduction; C content is high, and welding property is poor.
The investigation of Q235B coil of strip production performance actual achievement
Table 1 Q235B thickness, performance range cartogram
Can find out from table 1:
Q235 produces thickness below 7.5mm, and ys is at 275～475MPa, and tensile strength is at 405～595MPa, unit elongation 26～45.5%;
Q235 produces thickness more than 7.5mm, and ys is at 245～395MPa, and tensile strength is at 370～520MPa, unit elongation 23～40.5%;
Table 2 Q235B is less than 7.5mm thickness and performance index frequency table
Table 3 Q235B is greater than 7.5mm thickness and performance index frequency table
Can find out from table 2, table 3: the ys of Q235B (less than 7.5mm) mainly be in 310～430MPa, tensile strength mainly at 440～520MPa scope, unit elongation mainly 30～38%, to produce main thickness be 6-3mm;
The ys of Q235B (greater than 7.5mm) mainly be in 300～360MPa, tensile strength mainly at 450～490MPa scope, unit elongation mainly 29～37%, to produce main thickness be 7.5-14mm;
The Q235B coil of strip is produced the investigation of composition actual achievement, and 662 stove Q235B are carried out C, Si, Mn element statistics.
Table 4 Q235B steel C, Si, Mn scope cartogram
Can find out from table 4:
Q235 steel C average content is 0.15%, the Mn average content is 0.40%;
Table 5C, Si, the Mn composition frequency
Can find out from table 5: Q235B steel heat analysis C content is main 0.13～0.18%, Mn content is mainly 0.36～0.46%.
National standard (GB700) is to Q235B composition, performance requriements and the contrast of production actual achievement, and is as shown in table 6:
Table 6 composition, performance requriements and production actual achievement
Can find out from table 6: the rich amount of coils of hot-rolled steel Q235B intensity is big, and toughness is low.
Summary of the invention
Technical problem to be solved by this invention provides a kind of working method of coils of hot-rolled steel; This method has reduced C in the Q235B composition of steel, Mn content; Adopt suitable rolling technology and cooling control technology; Improve the over-all properties of Q235B steel, produce low cost, high performance Q235B coils of hot-rolled steel, in line with the theory realization energy-saving and emission-reduction of green iron and steel.
The working method of a kind of coils of hot-rolled steel of the present invention comprises:
1) after composition designs, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, tap molten steel; 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 handled 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 first stove in the water yield 25～30t of Baogang, liquid level 550～580mm; In bag during quick change in the water yield 15～20t of Baogang, liquid level 350～400mm; Normally water time cast keep in the water yield 42～50t of Baogang, liquid level 950～1000mm changes the big Bao Shizhong water yield 35～40t of Baogang, liquid level 800～850mm, when bag stops watering in the continuous casting in Baogang's water yield be controlled at 8～15t, liquid level 200～350mm; The whole process protection cast, long nozzle depth of penetration 300～400mm;
3) with above-mentioned slab heating, slab thickness 1.20mm～16mm, tapping temperature is controlled at 1170～1260 ℃, time inside furnace 150～200min, soaking time 22～30min;
4) with the slab rolling after the above-mentioned heating, curling at last promptly gets coils of hot-rolled steel; When slab thickness 1.20mm～16mm, the finish rolling temperature in is controlled at 990～1080 ℃, and finishing temperature is controlled at 830～900 ℃, and curling temperature is controlled to be 600 ± 30 ℃, and cooling strategy is a leading portion.
Above-mentioned steps 1) in, the weight percent of said each composition of molten steel is as shown in table 7:
Table 7 ingredient standard
Above-mentioned steps 1) in, blows Ar time 5～8min, its bright circle≤200mm a little less than the ladle before the molten steel processing finishes in the converter smelting; Reinforced adjustment composition 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 2) in, liquidus temperature is controlled to be 1527 ℃ during continuous casting, and the bag temperature is controlled to be 1552 ± 7 ℃ in the target, and crystallizer protecting residue adopts low-carbon steel protecting slag.
Above-mentioned steps 3) in, when slab was heated, the heating process parameter was seen table 8.
Table 8 heating process parameter
Above-mentioned steps 4) in, during with slab rolling, rolling technological parameter is seen table 9.
Table 9 rolling technological parameter
Above-mentioned steps 4) in, the gained coils of hot-rolled steel is the Q235B coils of hot-rolled steel.
The low C composition design of Q235B guarantees that coil of strip has good plasticity and toughness, and its unit elongation improves more than 13%; The normal temperature ballistic work is enhanced about more than once, and good plasticity and toughness have improved cold-forming property; Avoid the bending cracking problem of gross distortion in the use of Q235B coil of strip, reduce quality objection; Low carbon component design guarantees surface quality of continuously cast slab good (traditional Q235B composition is in inferior peritectoid scope, and casting billet surface produces a large amount of crackles), realizes straight dress simultaneously, energy-saving and emission-reduction; Low carbon component design has improved the material welding property; Low Mn design reduces the alloy consumption, reduces production costs.
Adopt the TMCP rolling technology, the low finishing temperature and the temperature of curling guarantee that coil of strip organizes tiny, even; Coil of strip has kept the microstructure characteristic of P+F, and coil of strip performance anisotropy is little; The Q235B steel of low C, low Mn composition has good combination of strength and toughness.
Beneficial effect
1, the inventive method is simple, adopts the TMCP rolling technology, and low Mn design reduces the alloy consumption, reduces production costs.
2, gained Q235B coils of hot-rolled steel of the present invention, low carbon component design guarantees that coil of strip has good plasticity and toughness, has improved the material welding property, guarantees that simultaneously surface quality of continuously cast slab is good, realizes directly dress, energy-saving and emission-reduction.
Description of drawings
Fig. 1 is metallographic structure (500 times of amplifications) behind the Q235B 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 Q235B 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 Q235B 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 to the present invention is described and be not used in the restriction scope of the present invention.Should be understood that in addition those skilled in the art can do various changes or modification to 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 institute restricted portion equally.
Embodiment 1
1) after composition designs, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, tap molten steel; 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 handled at the argon station;
2) weight percent of each composition of molten steel after the above-mentioned tapping is followed successively by: C 0.05%, and Si 0.12%, and Mn 0.20%, P0.020%, and S 0.010%, and Als 0.034%, and all the other are iron and unavoidable impurities; Said molten steel is carried out continuous casting gets slab, wherein connect water unwrap when watering in first stove in the water yield 25t of Baogang, liquid level 550mm; In bag during quick change in the water yield 15t of Baogang, liquid level 350mm; Normally water time cast keep in the water yield 42t of Baogang, liquid level 950mm changes the big 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 slab heating, time inside furnace 150min, soaking time 22min, during slab thickness 2.55mm, tapping temperature is controlled at 1240 ℃;
4) with the slab rolling after the above-mentioned heating, the finish rolling temperature in is controlled at 1060 ℃, and finishing temperature is controlled at 880 ℃; Curling temperature is controlled to be 630 ℃, and cooling strategy is a leading portion, and curling at last, promptly to get sample number into spectrum be 1 Q235B coils of hot-rolled steel.Accompanying drawing 1 is seen in its metallographic structure, and the tensile property assay is seen table 10.
Embodiment 2
1) after composition designs, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, tap molten steel; 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 handled 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 0.17%, and Mn 0.30%, P0.010%, and S 0.005%, and Als 0.020%, and all the other are iron and unavoidable impurities; Said molten steel is carried out continuous casting gets slab, wherein connect water unwrap when watering in first stove in the water yield 30t of Baogang, liquid level 560mm; In bag during quick change in the water yield 18t of Baogang, liquid level 380mm; Normally water time cast keep in the water yield 45t of Baogang, liquid level 980mm changes the big 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 slab heating, time inside furnace 180min, soaking time 25min, during slab thickness 7.05mm, tapping temperature is controlled at 1180 ℃;
4) with the slab rolling after the above-mentioned heating, the finish rolling temperature in is controlled at 1000 ℃, and finishing temperature is controlled at 830 ℃; Curling temperature is controlled to be 600 ℃, and cooling strategy is a leading portion, and curling at last, promptly to get sample number into spectrum be 2 Q235B coils of hot-rolled steel.Accompanying drawing 2 is seen in its metallographic structure, and the tensile property assay is seen table 10, impacts assay and sees table 11.
Embodiment 3
1) after composition designs, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, tap molten steel; 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 handled at the argon station;
2) weight percent of each composition of molten steel after the above-mentioned tapping is followed successively by: C 0.09%, and Si 0.25%, and Mn 0.35%, P0.025%, and S 0.020%, and Als 0.015%, and all the other are iron and unavoidable impurities; Said molten steel is carried out continuous casting gets slab, wherein connect water unwrap when watering in first stove in the water yield 28t of Baogang, liquid level 580mm; In bag during quick change in the water yield 20t of Baogang, liquid level 400mm; Normally water time cast keep in the water yield 50t of Baogang, liquid level 1000mm changes the big 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 slab heating, time inside furnace 200min, soaking time 30min, during slab thickness 10.55mm, tapping temperature is controlled at 1170 ℃;
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 890 ℃; Curling temperature is controlled to be 570 ℃, and cooling strategy is a leading portion, and curling at last, promptly to get sample number into spectrum be 3 Q235B coils of hot-rolled steel.Accompanying drawing 3 is seen in its metallographic structure, and the tensile property assay is seen table 10, impacts assay and sees table 11.
Tensile property assay of the present invention is seen table 10, table 11 respectively with the impact assay.
Table 10 tensile property assay
Table 11 impacts assay
Claims (4)
1. the working method of a coils of hot-rolled steel comprises:
1) after composition designs, molten iron is carried out pre-treatment, converter smelting then, the nitrogen argon switches, tap molten steel, 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 handled at the argon station; The weight percent of wherein said each composition of molten steel is: C 0.05～0.09%, and Si 0.12～0.25%, and Mn 0.20～0.35%, P≤0.025%, and S≤0.020%, Als＜0.035%, all the other are iron and unavoidable impurities;
2) molten steel after the above-mentioned tapping is carried out continuous casting and gets slab, wherein connect water unwrap when watering in first stove in the water yield 25～30t of Baogang, liquid level 550～580mm; In bag during quick change in the water yield 15～20t of Baogang, liquid level 350～400mm; Normally water the water yield 42～50t of Baogang in time cast maintenance, liquid level 950～1000mm; Change the big 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 slab heating, slab thickness 1.20mm～16mm, tapping temperature is controlled at 1170～1260 ℃, time inside furnace 150～200min, soaking time 22～30min;
4) with the slab rolling after the above-mentioned heating, curling at last promptly gets coils of hot-rolled steel; When slab thickness 1.20mm～16mm, the finish rolling temperature in is controlled at 990～1080 ℃, and finishing temperature is controlled at 830～900 ℃, and curling temperature is controlled to be 600 ± 30 ℃, and cooling strategy is a leading portion;
Blow Ar time 5～8min, its bright circle≤200mm a little less than the ladle before the molten steel processing finishes in the converter smelting in the said step 1); Reinforced adjustment composition 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;
Said step 2) in, liquidus temperature is controlled to be 1527 ℃ during continuous casting, and middle bag temperature is controlled to be 1552 ± 7 ℃, and crystallizer protecting residue adopts low-carbon steel protecting slag.
2. the working method of a kind of coils of hot-rolled steel according to claim 1; It is characterized in that: the weight percent of each composition of tapping gained molten steel is followed successively by in the said step 1): C 0.07%, and Si 0.17%, and Mn 0.30%; P≤0.020%; S≤0.015%, Als≤0.020%, all the other are iron and unavoidable impurities.
3. the working method of a kind of coils of hot-rolled steel according to claim 1 is characterized in that: when in the said step 3) slab being heated, when 1.20mm≤slab thickness＜2.75mm, tapping temperature is controlled at 1230 ± 30 ℃;
When 2.75mm≤slab thickness＜3.50mm, tapping temperature is controlled at 1220 ± 30 ℃;
When 3.50mm≤slab thickness＜7.55mm, tapping temperature is controlled at 1200 ± 30 ℃;
When 7.55mm≤slab thickness≤16mm, tapping temperature is controlled at 1200 ± 30 ℃.
4. the working method of a kind of coils of hot-rolled steel according to claim 1; It is characterized in that: in the said step 4) during slab rolling; When 1.20mm≤slab thickness＜2.75mm, the finish rolling temperature in is controlled at 1050 ± 30 ℃, and finishing temperature is controlled at 870 ± 30 ℃;
When 2.75mm≤slab thickness＜3.50mm, the finish rolling temperature in is controlled at 1030 ± 30 ℃, and finishing temperature is controlled at 860 ± 30 ℃;
When 3.50mm≤slab thickness＜7.55mm, the finish rolling temperature in is controlled at 1020 ± 30 ℃, and finishing temperature is controlled at 860 ± 30 ℃;
When 7.55mm≤slab thickness≤16mm, the finish rolling temperature in is controlled at 1020 ± 30 ℃, and finishing temperature is controlled at 860 ± 30 ℃.
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| CN2011100413138A CN102127684B (en) | 2011-02-21 | 2011-02-21 | Method for producing hot rolled steel coils |
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| CN2011100413138A CN102127684B (en) | 2011-02-21 | 2011-02-21 | Method for producing hot rolled steel coils |
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| CN102127684B true CN102127684B (en) | 2012-11-28 |
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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—连铸生产技术会议文集》.2010,第332-337页. * |
| 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,第514-518页. * |
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