CN101792882A - Production method of boracic hot-rolled coil plates with low yield ratio - Google Patents
Production method of boracic hot-rolled coil plates with low yield ratio Download PDFInfo
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- CN101792882A CN101792882A CN 201010300113 CN201010300113A CN101792882A CN 101792882 A CN101792882 A CN 101792882A CN 201010300113 CN201010300113 CN 201010300113 CN 201010300113 A CN201010300113 A CN 201010300113A CN 101792882 A CN101792882 A CN 101792882A
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Abstract
The invention relates to a thin slab continuous casting and rolling process method in metallurgy, in particular to a production method of boracic hot-rolled coil plates with low yield ratio; the technical proposal is that: 1. smelting chemical compositions are as follows by weight percentage: 0.05-0.25wt% of C, less than or equal to 0.5wt% of Si, 0.5-1.5wt% of Mn, less than or equal to 0.03wt% of P, less than or equal to 0.03wt% of B, the remaining is Fe and unavoidable impurities; 2. continuous casting middle-thin slab is rolled through multiple passes within an austenite recrystallization temperature range after being heated to 1050-150 DEG C, and the finishing temperature is 800-900 DEG C; 3. in the cooling process, the coiling temperature is cooled in a cascading manner, the coiling temperature is 550-750 DEG C, so as to obtain the hot-rolled coil plates with 2.5-6.0mm of thickness and 900-1300mm of width; in the invention, C and Mn are adopted to improve the tensile strength of the steel, the yield strength of the steel is reduced by adopting boron; in the hot rolling process, high tensile strength and low yield strength are realized by combination of all elements at different temperatures, so as to ensure the intensity of the steel and improve the formation performance of the steel.
Description
Affiliated technical field:
The present invention relates to a kind of metallurgical production method of the low yield strength ratio hot-rolled coil of the processing method, particularly a kind of boracic of medium thin slab continuous casting and rolling already.
Background technology:
Boron (symbol of element B) element is as one of extremely active element in the steel, has extremely strong avidity with residual nitrogen, oxygen in the steel, be very easy to generate nitrogen, the oxide compound of boron, thereby residual nitrogen in the steel and oxygen solid solution, to alleviate the influence of residual gas to the steel yield strength.Because the unstable of boron, strong to the susceptibility of the performance of hot-rolled coil and tissue, if add-on and unreasonable with the hot rolling technology coupling is easy to occur product quality problem, cause production cost to improve, influence technical indicators such as tensile strength, yield tensile ratio; Therefore, how controlling the add-on of boron and how to mate with hot rolling technology, is the technical problem that this area needs to be resolved hurrily.
Summary of the invention:
The object of the invention provides a kind of production method of low yield strength ratio hot-rolled coil of boracic, and the hot-rolled steel sheet tensile strength height of being produced, yield strength is low, yield tensile ratio is low, and forming property is good, solves the problems referred to above that exist in the background technology.
Technical scheme of the present invention is:
A kind of production method of low yield strength ratio hot-rolled coil of boracic comprises smelting, continuous casting, hot rolling, refrigerating work procedure, and its special feature is:
1. the chemical ingredients of Ye Lianing is (weight percent) C:0.05～0.25wt%, Si≤0.5wt%, Mn:0.5～1.5wt%, P≤0.03wt%, S≤0.03wt%, B≤0.02wt%, and surplus is Fe and unavoidable impurities;
2. 1050-1150 ℃ of heating of continuous casting medium thin slab process is rolling through multi-pass in the austenite recrystallization temperature scope, finishing temperature 800-900 ℃;
3. in process of cooling, adopt segmentation to be cooled to coiling temperature, coiling temperature 550-750 ℃, obtaining thickness is that 2.5-6.0mm, width are the hot-rolled coil of 900-1300mm.
Medium thin slab thickness of the present invention is 135mm, and pulling rate 1.0-4.5m/min, strand enter furnace temp 600-950 ℃, 1000-1200 ℃ of roughing start rolling temperature, 800-900 ℃ of finish rolling finishing temperature carried out the laminar flow cooling afterwards or carried out air cooling, coiling temperature 550-700 ℃.
In order to reduce yield tensile ratio, smelting procedure comprises converter smelting, LF refining, adds boron in LF refining later stage process; In the course of hot rolling finishing temperature 850-900 ℃, coiling temperature 600-700 ℃.
Preferred implementation of the present invention:
1, the chemical ingredients of steel grade is C:0.05～0.20wt%, Si≤0.30wt%, Mn:0.5～1.3wt%, P≤0.03wt%, S≤0.03wt%, B≤0.01wt%, and surplus is Fe and unavoidable impurities.
2, carry out the LF refining behind the converter smelting.
3, thickness of strand is the medium thin slab of 130-160mm, and the hot rolling compression ratio is 22-54.
4, finishing temperature 800-900 ℃; Coiling temperature 550-750 ℃.
5, the segmentation cooling is to disperse thick cold-peace to disperse two sections of cold sperms or multi-stage type cooling, allows air cooling before the water-cooled and after the water-cooled.
6, water cooling speed≤40 ℃.
In the low yield strength ratio hot rolled plate making process of the present invention, its process choice is analyzed as follows:
1. rolling technology: adopt heat, high-temperature final rolling, high temperature coiling technique, help boron under the high temperature and combine, forms a large amount of boron nitride and boron oxide with oxygen, nitrogen, with residual nitrogen, oxygen solid solution in the steel, thus the reduction yield strength, the plasticity of raising steel.
2. process for cooling: adopt behind the first air cooling water-cooled air cooling process for cooling again, the leading portion air cooling reduces speed of cooling, and crystal grain has the sufficient time to grow up; Water-cooled section crystal grain thinning improves intensity; The back segment air cooling makes the temperature of steel strips after the water-cooled anti-red, helps homogeneous grain size, therefore, and process for cooling control structure of steel homogeneity and assurance advantages of higher tensile strength, thereby the comprehensive mechanical property and the forming property of assurance steel.
Details are as follows to chemical ingredients effect in the low yield strength ratio hot-rolled sheet below:
C: the most basic strengthening element in the steel, dispersible carbon is distributed in the ferrite crystal boundary to tension intensity effect highly significant in the present invention, but carbon content can not be too high, otherwise can cause the welding property of steel to descend, therefore, carbon content is controlled between the 0.05-0.15wt%.
Si: in steel, play the solution strengthening effect, help stoping separating out of carbide, but unfavorable to the coating adhesive property of steel, therefore, suitably control Si content less than 0.10wt%.
Mn: be that the solution strengthening element helps moving to right of C curve again, favourable to improving intensity, for taking into account intensity and moulding its content generally is controlled between the 0.20-0.50wt%.
P, S are the remaining impurities element, and be unfavorable to welding property, should reduce its content as far as possible.
B: strong with oxygen, bonding force in the steel, with residual oxygen and nitrogen form boron oxygen, change thing, the present invention utilizes boron fixed nitrogen, oxygen, alleviates the influence to the steel surrender of oxygen, nitrogen, thereby reduces the yield strength of steel, reduces yield tensile ratio.
Beneficial effect of the present invention and advantage: the present invention adopts carbon, manganese to improve the tensile strength of steel, adopt boron to reduce the yield strength of steel, the combination of each element of control under differing temps realizes advantages of higher tensile strength and lower yield strength in course of hot rolling, can guarantee that the intensity of steel improves the forming property of steel simultaneously again.From the composition design, alloying constituent is few, addition is low, helps saving alloying element, reduces environmental influence, has application promise in clinical practice; The present invention effectively reduces yield strength in proof strength, keep having solved the problem of higher-strength steel direct forming difficulty than low yield strength ratio.
Embodiment:
The invention will be further described by the following examples.
In an embodiment, the chemical ingredients of steel is: C:0.05～0.07wt%, Si≤0.03wt%, Mn:0.15～0.2wt%, P≤0.020wt%, S≤0.010wt%, B≤0.002wt%, surplus is Fe and unavoidable impurities.
Adopt converter that molten iron smelting is become molten steel, molten steel adds reductor and alloying element through refining, carries out deoxidation alloying.Molten steel is through continuous casting growth 13.5m, wide 1260mm, thick 135mm continuously cast bloom after the refining, enter walking beam furnace and be heated to 1100-1150 ℃, start rolling temperature 1030-1080 ℃, finishing temperature 870-890 ℃, coiling temperature 660-680 ℃, the laminar flow cooling adopts back segment to disperse the type of cooling.
Detect through material tensile test, present embodiment is produced hot-rolled coil good mechanical properties, tensile strength 335MPa, yield strength 220MPa, yield tensile ratio 0.66, unit elongation 47%.
The metallographic structure of steel that present embodiment is produced is viewed as, and sulfide-basedly is mingled with 0.5 grade, and the spherical oxide class is mingled with 0.5 grade.Be organized as ferrite+minority and divide the disperse perlite, 2.5 grades of free cementites.
Claims (9)
1. the production method of the low yield strength ratio hot-rolled coil of a boracic is characterized in that comprising smelting, continuous casting, hot rolling, refrigerating work procedure, it is characterized in that:
1. the chemical ingredients of Ye Lianing is (weight percent) C:0.05～0.25wt%, Si≤0.5wt%, Mn:0.5～1.5wt%, P≤0.03wt%, S≤0.03wt%, B≤0.02wt%, and surplus is Fe and unavoidable impurities;
2. 1050-1150 ℃ of heating of continuous casting medium thin slab process is rolling through multi-pass in the austenite recrystallization temperature scope, finishing temperature 800-900 ℃;
3. in process of cooling, adopt segmentation to be cooled to coiling temperature, coiling temperature 550-750 ℃, obtaining thickness is that 2.5-6.0mm, width are the hot-rolled coil of 900-1300mm.
2. according to the production method of the low yield strength ratio hot-rolled coil of the described boracic of claim 1, it is characterized in that medium thin slab thickness is 135mm, pulling rate 1.0-4.5m/min, strand enters furnace temp 600-950 ℃, 1000-1200 ℃ of roughing start rolling temperature, 800-900 ℃ of finish rolling finishing temperature carried out the laminar flow cooling afterwards or carried out air cooling, coiling temperature 550-700 ℃.
3. according to the production method of the low yield strength ratio hot-rolled coil of claim 1 or 2 described boracics, it is characterized in that smelting procedure comprises converter smelting, LF refining, adds boron in LF refining later stage process; In the course of hot rolling finishing temperature 850-900 ℃, coiling temperature 600-700 ℃.
4. according to the production method of the low yield strength ratio hot-rolled coil of the described boracic of claim 3, the chemical ingredients that it is characterized in that steel grade is C:0.05～0.20wt%, Si≤0.30wt%, Mn:0.5～1.3wt%, P≤0.03wt%, S≤0.03wt%, B≤0.01wt%, and surplus is Fe and unavoidable impurities.
5. according to the production method of the low yield strength ratio hot-rolled coil of the described boracic of claim 3, it is characterized in that carrying out the LF refining behind the converter smelting.
6. according to the production method of the low yield strength ratio hot-rolled coil of the described boracic of claim 3, it is characterized in that thickness of strand is the medium thin slab of 130-160mm, the hot rolling compression ratio is 2254.
7. according to the production method of the low yield strength ratio hot-rolled coil of the described boracic of claim 3, it is characterized in that finishing temperature 800-900 ℃; Coiling temperature 550-750 ℃.
8. according to the production method of the low yield strength ratio hot-rolled coil of the described boracic of claim 3, it is characterized in that the segmentation cooling is to disperse thick cold-peace to disperse two sections of cold sperms or multi-stage type cooling, allows air cooling before the water-cooled and after the water-cooled.
9. according to the production method of the low yield strength ratio hot-rolled coil of the described boracic of claim 3, it is characterized in that water cooling speed≤40 ℃.
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| CN 201010300113 CN101792882A (en) | 2010-01-08 | 2010-01-08 | Production method of boracic hot-rolled coil plates with low yield ratio |
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| CN 201010300113 CN101792882A (en) | 2010-01-08 | 2010-01-08 | Production method of boracic hot-rolled coil plates with low yield ratio |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102433507A (en) * | 2012-01-16 | 2012-05-02 | 江苏省沙钢钢铁研究院有限公司 | Low yield ratio and high strength weldable steel plate and preparation technology thereof |
| CN103469056A (en) * | 2013-08-15 | 2013-12-25 | 甘肃酒钢集团宏兴钢铁股份有限公司 | High-tensile-to-yield-ratio common hot rolled steel plate and making method thereof |
| CN103952623A (en) * | 2014-04-28 | 2014-07-30 | 武汉钢铁(集团)公司 | Steel for boron-containing piston rod and production method thereof |
| CN111286673A (en) * | 2020-03-27 | 2020-06-16 | 武汉钢铁有限公司 | High-formability boron-containing steel with tensile strength of more than or equal to 320MPa and production method thereof |
-
2010
- 2010-01-08 CN CN 201010300113 patent/CN101792882A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102433507A (en) * | 2012-01-16 | 2012-05-02 | 江苏省沙钢钢铁研究院有限公司 | Low yield ratio and high strength weldable steel plate and preparation technology thereof |
| CN102433507B (en) * | 2012-01-16 | 2013-12-25 | 江苏省沙钢钢铁研究院有限公司 | Low yield ratio and high strength weldable steel plate and preparation technology thereof |
| CN103469056A (en) * | 2013-08-15 | 2013-12-25 | 甘肃酒钢集团宏兴钢铁股份有限公司 | High-tensile-to-yield-ratio common hot rolled steel plate and making method thereof |
| CN103469056B (en) * | 2013-08-15 | 2016-04-13 | 甘肃酒钢集团宏兴钢铁股份有限公司 | High yield ratio ordinary hot rolled steel plate and manufacture method thereof |
| CN103952623A (en) * | 2014-04-28 | 2014-07-30 | 武汉钢铁(集团)公司 | Steel for boron-containing piston rod and production method thereof |
| CN103952623B (en) * | 2014-04-28 | 2015-10-28 | 武汉钢铁(集团)公司 | A kind of boracic piston rod steel and production method thereof |
| CN111286673A (en) * | 2020-03-27 | 2020-06-16 | 武汉钢铁有限公司 | High-formability boron-containing steel with tensile strength of more than or equal to 320MPa and production method thereof |
| CN111286673B (en) * | 2020-03-27 | 2021-05-25 | 武汉钢铁有限公司 | High-formability boron-containing steel with tensile strength of more than or equal to 320MPa and production method thereof |
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Open date: 20100804 |