CN100525953C - Technique for preventing surface crack of continuous casting steel billet for petroleum casing - Google Patents
Technique for preventing surface crack of continuous casting steel billet for petroleum casing Download PDFInfo
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- CN100525953C CN100525953C CNB2005101336307A CN200510133630A CN100525953C CN 100525953 C CN100525953 C CN 100525953C CN B2005101336307 A CNB2005101336307 A CN B2005101336307A CN 200510133630 A CN200510133630 A CN 200510133630A CN 100525953 C CN100525953 C CN 100525953C
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Abstract
The invention provides a art method for prevent oil annular tube continuous casting billet surface crack, said billet is used for oil annular tube, its steps include : (1) electric arc furnace (EAF) smelt station, (2) ladle refining furnace (LF) process station, (3) vacuum refining furnace (VD) process station, (4) continuous casting (CCM) process station. The effect of the invention is: using said technology, changing and improving constantly under the condition of using 150t super high-capacity arc furnace, 150t ladle refining furnace, 150t vacuum refining furnace, and round billet continuous casting machine with 6 flows in one machine, it prevents the oil annular tube continuous casting billet surface crack through the production of two steel types of 39Mn2V and 39Mn2V/l, improves the quality of the steel species and reduces waste by 60%.
Description
Technical field
The present invention relates to be used in a kind of API standard produce the production technology of N80-1 class petroleum casing pipe with continuous casting billet, particularly a kind of process that prevents surface crack of continuous casting steel billet for petroleum casing.
Background technology
In STEELMAKING PRODUCTION, rolling 39Mn2V, 39Mn2V/1 are two steel grades that are applicable to N80-1 class petroleum casing pipe in the production " sleeve pipe and oil pipe standard " (API SPEC 5CT standard), have been widely used in Shengli Oil Field at present, told the main oil plays in the whole nation such as breathing out oil field, Qinghai Oil Field, Liaohe Oil Field.The main production technology of this kind of current domestic production is electric arc furnaces (EAF), ladle refining furnace (LF), vacuum refining furnace (VD), continuous casting (CCM), but aborning, these two steel grades quality stability in the operation of rolling is relatively poor, occur in a large number rolling over outside the body after rolling through being everlasting, defective such as crackle, and then cause a large amount of waste products to produce.Cause the main cause of this type of defective to exceed standard with non-metallic inclusion and the strand cooling procedure in internal stress excessive, strand low temperature aligning when producing is relevant, this and production technology have very big relation, main cause is:
At first, in the steelmaking process, because general production technology mostly uses aluminium, silicomanganese, Antaciron to carry out deoxidation, therefore if, the silicate that easy hard, indeformable tiny solid alumina inclusion of generation and silicate and metal oxide chemical combination form in molten steel is mingled with, adequate time come-up that the two do not have, can accumulate in the steel, destroy the basic continuity of steel, cause the tissue odds of steel even, influence the various performances of steel.
In addition, when continuous casting, because the manganese content of these two steel grades is all in 1.0～2.0% scopes, and in general carbon steel, manganese content is only below 0.70%, and is little to the performance impact of steel, because manganese content is increased at 1.0%～2.0% o'clock, intensity raising, plasticity are reduced, easily make grain coarsening, internal stress is bigger.And steel has a brittleness temperature scope in the time of 700～900 ℃, in this temperature range, easily cracks as the effect that is subjected to stress when aligning.Therefore,, must adopt adjust the distribution of secondary cooling water, make the surface temperature of continuous casting billet when aligning avoid the pressure of this temperature range and suitable adjustment straightening machine for fear of this phenomenon.
Summary of the invention
At above-mentioned situation, the objective of the invention is under the prerequisite that does not change conventional process flow, improving the molten steel cleanliness factor by conventional method, when reducing non-metallic inclusion, provide a kind of process that prevents surface crack of continuous casting steel billet for petroleum casing.
For achieving the above object, the technical solution used in the present invention provides a kind of process that prevents surface crack of continuous casting steel billet for petroleum casing, and its concrete steps are as follows:
(1) electric arc furnaces (EAF) is smelted station
During electric furnace smelting, for remedying the deficiency of carbon content in the steel scrap, the mixed carbon comtent by reasonably ensureing furnace charge with addition of molten iron and the pig iron guarantees to have made as early as possible Pao Droplets slag in 1.0 ~ 1.5% scopes, finished the dephosphorization decarburization in 25～35 minutes; For avoiding five-harmful elements in the operation of rolling (Pb, Sn, As, Sb, Bi) poly-partially at the crystal boundary place, avoid the higher steel scrap of disposable a large amount of use five-harmful elements (Pb, Sn, As, Sb, Bi) content during batching, when smelting, pass through to add molten iron and sponge iron simultaneously in order to the five-harmful elements in the dilution molten steel; Adopt eccentric furnace bottom slag free tapping, prevent that oxidizing slag from entering in the ladle, utilize and stay the method for steel in stove, to stay part molten steel (near 20t), guarantee certain electric furnace steel tapping temperature; Steel coolant-temperature gage ≧ 1520 ℃ in half an hour after tapping, guarantee molten steel in vacuum refining furnace, have the enough high vacuum time for ≧ 8Min and calm time;
(2) ladle refining furnace (LF) is handled station
Stir a little less than refining finishes afterwards by argon gas and guarantee that molten steel temperature in casting process is even and the suitable degree of superheat is arranged, last casting temperature is controlled at following scope:
Open and water furnace temperature: T
L+ 80+ (0 ~ 5) ℃
Connect and water furnace temperature: T
L+ 55+ (0 ~ 5) ℃
In the formula: T
L--the liquidus temperature of-----steel grade
The field trash of having given birth to is fully floated, will avoid new field trash to generate simultaneously;
(3) vacuum refining furnace (VD) is handled station
Vacuum refining furnace promotes inclusion floating by the vacuum BOTTOM ARGON BLOWING, improves the molten steel degree of purity; Prolong high vacuum time Wei ≧ 8Min and calm time then, utilization Ca treatment technology makes string bunch shape Al
2O
3Become the spherical low melting point CaO-Al that is easy to discharge
2O
3Be field trash, and guarantee that hello Al silk and CaSi silk time are Jian Ge ≧ 10Min; The control vacuum refining furnace concluding time, when the big Baogang of continuous casting water remained 40～50t, next Baogang's water will possess last continuous-casting conditions; When remaining 30～40t, next Baogang's water rises and hangs on continuous casting;
(4) continuous casting (CCM) station
The long nozzle of the big bag of continuous casting adopts sealing ring, to the omnidistance Argon of big canning tube, middle bag liquid level 〉=30t, use corresponding water meter, assurance secondary cooling water spraying, and shower waters selection tandem in 1,2 districts when producing, 3 district's shower waters are controlled at 30L/Min, 4 district's shower waters are closed, and 3 districts, 4 district's shower water control modes are become manual mode by the tandem mode; First the hot base pressure of straightening machine is set to zero, has avoided 700～900 ℃ in fragility sensitive temperature zone; After cast big bag of later stage waters steel and finishes, pulling rate is progressively reduced to the starting pulling rate, residue molten steel height 〉=200mm in the tundish is involved in the strand to reduce field trash.
Effect of the present invention is by adopting above technology, continuous modification under appointed conditions such as use 150t ultra high electric arc furnace, 150t ladle refining furnace, 150t vacuum refining furnace, 1 machine, 6 stream curved circular billet continuous casting machines and perfect, finally determined the new production technology of 39Mn2V, 39,Mn2,V/1 two steel grades, prevented the appearance of surface crack of continuous casting steel billet for petroleum casing, improved the quality of steel grade, and rejection number has been reduced by 60%.
The specific embodiment
Be that φ 270mm, φ 310mm strand are embodiment with 39Mn2V, 39Mn2V/1 section below, a kind of process of surface crack of continuous casting steel billet for petroleum casing that prevents of the present invention is illustrated.
Because internal stress is very big in 39Mn2V, the 39Mn2V/1 strand cooling procedure, strand is low excessively as if temperature before entering the straightening machine, will behind aligning, produce the aligning crackle, therefore, we adjust the intensity of secondary cooling when producing these two steel grades, weakened the water yield in He Si districts, three districts, two cold-zones, the cooling water inflow in Jiang San district is reduced to 30L/min, and Jiang Si district water is closed, in order to improve the strand straightening temperature, avoid 700～900 ℃ brittleness temperature scope.Also adjust simultaneously the pressure of first straightening machine, the hot base pressure of first straightening machine has been reduced to 0MPa, reduced the possibility that causes the core crackle because of when the strand internal stress is excessive, aligning.
A kind of process that prevents surface crack of continuous casting steel billet for petroleum casing of the present invention mainly is under the prerequisite that is not changing existing total production procedure, and is as follows to the process procedure concrete operations of each flow process:
1, electric arc furnaces (EAF) is smelted station
During electric furnace smelting, for remedying the deficiency of carbon content in the steel scrap, by reasonably ensureing that with addition of the molten iron and the pig iron mixed carbon comtent of furnace charge is in 1.0～1.5% scopes, guarantee to have made as early as possible Pao Droplets slag, in 25～35 minutes, finish the task of dephosphorization decarburization, prevent the phenomenon of long Molten Steel over-oxidation that causes of smelting cycle and then increase oxide inclusions.For avoiding five-harmful elements (Pb, Sn, As, Sb, Bi) poly-partially at the crystal boundary place, reduce the elevated temperature strength and the plasticity of steel, folding or crackle outside in the operation of rolling, producing, by rational proportion scheme, the higher steel scrap of disposable a large amount of use five-harmful elements content when avoiding preparing burden passes through to add molten iron and sponge iron simultaneously in order to the five-harmful elements in the dilution molten steel when smelting.Adopt eccentric furnace bottom slag free tapping, prevent that oxidizing slag from entering in the ladle, utilize and stay the method for steel in stove, to stay part molten steel (about 20t).Guarantee suitable electric furnace steel tapping temperature, this is not only the key that guarantees the molten steel quality, and is to guarantee to produce the key of carrying out smoothly, and its computing formula is:
Add the temperature drop that alloy and slag making material cause during the liquidus temperature of tapping temperature=steel (1530 ℃)+(40～50 ℃)+tapping
Calculate back interior steel coolant-temperature gage half an hour of guaranteeing to tap ≧ 1520 ℃ in strict accordance with above-mentioned formula.To reduce refining station heat time heating time, guarantee that molten steel has enough high vacuum time (≧ 8Min) and calm time at vacuum refining furnace.
2, ladle refining furnace (LF) is handled station
Refining treatment is a control field trash important link, not only will allow the field trash of having given birth to fully float, but also will avoid new field trash to generate.Therefore require it in deployed each composition, refining finish the back stir a little less than by argon gas guarantee molten steel in casting process temperature evenly and the suitable degree of superheat is arranged, last casting temperature is controlled at following scope:
Open and water furnace temperature: T
L+ 80+ (0～5) ℃
Connect and water furnace temperature: T
L+ 55+ (0～5) ℃
In the formula: T
L--the liquidus temperature of-----steel grade
Prevent because of casting strand inner inclusion and the aligning crackle that the higher secondary oxidation that causes of temperature causes.
3, vacuum refining furnace (VD) is handled station
The VD stove reaches the purpose to molten steel dehydrogenation, denitrogenation, deoxidation and desulfurization by the vacuum BOTTOM ARGON BLOWING, promotes inclusion floating, improves the molten steel degree of purity.When accomplishing these, prolong high vacuum time (≧ 8Min) and calm time, control well feed Al silk and CaSi silk time to improve the calcium treatment effect, require to feed Al silk and CaSi silk Shi Jian Jian Ge ≧ 10Min, handle by Ca, can be fully with the residual Al in the steel
2O
3Be converted into low-melting combination product, discharge molten steel easily, the category-B that is beneficial to fully remove in the molten steel is mingled with (Al
2O
3).Reach inclusion modification and cleaning molten steel effect, control the VD concluding time well, when the surplus 40～50t of the big Baogang of continuous casting water, next Baogang's water will possess last continuous-casting conditions; When remaining 30～40t, next Baogang's water rises and hangs on continuous casting.So just guaranteed that molten steel has the enough calm time before cast, fully float field trash.
4, continuous casting (CCM) station
The big bag long nozzle of continuous casting adopts sealing ring, guarantees that the omnidistance Argon of big canning tube guarantees that middle bag liquid level 〉=30t, two steel grades still use each self-corresponding water meter in the operation card, guarantees that the secondary cooling water spraying is good.As shown in the table, 1,2 district's shower waters are selected tandem during production, and 3 district's shower waters are controlled at 30L/Min, and 4 district's shower waters are closed, and control mode becomes manual mode by original tandem mode; First the hot base pressure of straightening machine is set to zero, has avoided fragility sensitive temperature zone.After cast big bag of later stage waters steel and finishes, pulling rate progressively must be reduced to the starting pulling rate, residue molten steel height 〉=200mm is above in the tundish is involved in the strand to reduce field trash.
1. the adjustment of secondary cooling water intensity
| Φ 270mm specification | 1 district water yield L/min | Control mode | 2 district water yield L/min | Control mode | 3 district water yield L/min | Control mode | 4 district water yield L/min | Control mode | Amount to L/min |
| Before the adjustment | 29.7 | Tandem | 56.5 | Tandem | 33.0 | Tandem | 33.0 | Tandem | 152.3 |
| After the adjustment | 29.7 | Tandem | 56.5 | Tandem | 30 | Manually | 0 | Manually | 116.2 |
| Φ 310mm specification | 1 district water yield L/min | Control mode | 2 district water yield L/min | Control mode | 3 district water yield L/min | Control mode | 4 district water yield L/min | Control mode | Amount to L/min |
| Before the adjustment | 49.9 | Tandem | 60.2 | Tandem | 31.0 | Tandem | 31.0 | Tandem | 172.1 |
| After the adjustment | 49.9 | Tandem | 60.2 | Tandem | 30 | Manually | 0 | Manually | 140.1 |
2. to the adjustment of the pressure of first straightening machine
Claims (1)
1, a kind of process that prevents surface crack of continuous casting steel billet for petroleum casing, its concrete steps are as follows:
(1) electric arc furnaces (EAF) is smelted station
During electric furnace smelting, for remedying the deficiency of carbon content in the steel scrap, the mixed carbon comtent by reasonably ensureing furnace charge with addition of molten iron and the pig iron guarantees to have made as early as possible foamed slag in 1.0～1.5% scopes, finished the dephosphorization decarburization in 25～35 minutes; For avoiding five-harmful elements in the operation of rolling, its five-harmful elements is Pb, Sn, As, Sb, Bi, poly-partially at the crystal boundary place, avoid the higher steel scrap of the above-mentioned five-harmful elements content of disposable a large amount of use during batching, when smelting, pass through to add molten iron and sponge iron simultaneously in order to the five-harmful elements in the dilution molten steel; Adopt eccentric furnace bottom slag free tapping, prevent that oxidizing slag from entering in the ladle, utilize and stay the method for steel to stay the part molten steel in stove, molten steel guarantees certain electric furnace steel tapping temperature near 20t; Steel coolant-temperature gage ≧ 1520 ℃ in half an hour after tapping, guarantee molten steel in vacuum refining furnace, have the enough high vacuum time for ≧ 8Min and calm time;
(2) ladle refining furnace (LF) is handled station
Stir a little less than refining finishes afterwards by argon gas and guarantee that molten steel temperature in casting process is even and the suitable degree of superheat is arranged, last casting temperature is controlled at following scope:
Open and water furnace temperature: T
L+ 80+ (0～5) ℃
Connect and water furnace temperature: T
L+ 55+ (0～5) ℃
In the formula: T
L--the liquidus temperature of-----steel grade
The field trash of having given birth to is fully floated, will avoid new field trash to generate simultaneously;
(3) vacuum refining furnace (VD) is handled station
Vacuum refining furnace promotes inclusion floating by the vacuum BOTTOM ARGON BLOWING, improves the molten steel degree of purity; Prolong high vacuum time Wei ≧ 8Min and calm time then, utilization Ca treatment technology makes string bunch shape Al
2O
3Become the spherical low melting point CaO-Al that is easy to discharge
2O
3Be field trash, and guarantee that hello Al silk and CaSi silk time are Jian Ge ≧ 10Min; The control vacuum refining furnace concluding time, when the big Baogang of continuous casting water remained 40～50t, next Baogang's water will possess last continuous-casting conditions; When remaining 30～40t, next Baogang's water rises and hangs on continuous casting;
(4) continuous casting (CCM) station
The long nozzle of the big bag of continuous casting adopts sealing ring, to the omnidistance Argon of big canning tube, middle bag liquid level 〉=30t, use corresponding water meter, assurance secondary cooling water spraying, and shower waters selection tandem in 1,2 districts when producing, 3 district's shower waters are controlled at 30L/Min, 4 district's shower waters are closed, and 3 districts, 4 district's shower water control modes are become manual mode by the tandem mode; First the hot base pressure of straightening machine is set to 0MPa, has avoided 700～900 ℃ in fragility sensitive temperature zone; After cast big bag of later stage waters steel and finishes, pulling rate is progressively reduced to the starting pulling rate, residue molten steel height 〉=200mm in the tundish is involved in the strand to reduce field trash.
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| CN100542715C (en) * | 2007-10-19 | 2009-09-23 | 攀钢集团攀枝花钢铁研究院 | Continuous casting method of 450mm 360mm medium carbon manganese steel bloom |
| CN101565771B (en) * | 2009-04-29 | 2011-01-19 | 天津钢管集团股份有限公司 | Calcium treatment method for molten steel in steel making |
| CN101792843B (en) * | 2010-01-19 | 2011-09-21 | 南京钢铁股份有限公司 | Production process of Nb-containing mill coil for automobile |
| CN101850409B (en) * | 2010-06-08 | 2012-02-29 | 攀钢集团钢铁钒钛股份有限公司 | Continuous casting method |
| CN102059331A (en) * | 2010-11-26 | 2011-05-18 | 首钢总公司 | Continuous casting blank hot charging and hot conveying process for preventing surface crack of steel plate |
| CN105458205B (en) * | 2015-12-03 | 2017-12-19 | 攀钢集团成都钢钒有限公司 | The production method of high nickel steel Gr.8 continuous cast round billets |
| CN115627409A (en) * | 2022-10-24 | 2023-01-20 | 石钢京诚装备技术有限公司 | Production method for reducing surface crack rate of medium-carbon boron-containing round steel |
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| US4494999A (en) * | 1982-07-09 | 1985-01-22 | Mannesmann Aktiengesellschaft | Process for making fine-grain weldable steel sheet for large-diameter pipes |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4494999A (en) * | 1982-07-09 | 1985-01-22 | Mannesmann Aktiengesellschaft | Process for making fine-grain weldable steel sheet for large-diameter pipes |
Non-Patent Citations (4)
| Title |
|---|
| P110石油管坯水平连铸工艺改进和质量控制. 钟春生，彭自胜.特殊钢，第24卷第1期. 2003 |
| P110石油管坯水平连铸工艺改进和质量控制. 钟春生，彭自胜.特殊钢，第24卷第1期. 2003 * |
| 电炉钢连铸坯表面裂纹攻关. 谭俊敏，周国平，姚家华，于平.特殊钢，第21卷第2期. 2000 |
| 电炉钢连铸坯表面裂纹攻关. 谭俊敏，周国平，姚家华，于平.特殊钢，第21卷第2期. 2000 * |
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Effective date of registration: 20190624 Address after: No. 396 Jintang Highway, Dongli District, Tianjin 300301 Patentee after: Tianjin Steel Tube Manufacturing Co., Ltd. Address before: 300301 Jintang Road, Dongli District, Tianjin Patentee before: Tianjin Steel Pipe Group Co., Ltd. |