CN103361460B - Production method for effectively controlling gas content in beam blank - Google Patents
Production method for effectively controlling gas content in beam blank Download PDFInfo
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- CN103361460B CN103361460B CN201310320273.XA CN201310320273A CN103361460B CN 103361460 B CN103361460 B CN 103361460B CN 201310320273 A CN201310320273 A CN 201310320273A CN 103361460 B CN103361460 B CN 103361460B
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Abstract
The invention relates to a production method for effectively controlling gas content in beam blank. The production method comprises processes of raw material pre-treating, converter smelting, deoxidation alloying, and refining, wherein the materials maintain dry, the process of adding slag charge is moved forward to avoid adding material operation 3 minutes before the terminal point; the process of modifying converter slag is moved backward, synthesis slag is added on top of the steel slag after the converter furnace has been stocked with steels other than going into the converter furnace with the steel water, synthesis slag is subjected to a ultra-high-temperature baking by utilizing the steel slag to maximumly reduce the water in the synthesis slag and the crystal water contained by the synthesis slag; electrode powder replaces carbon powder to match with carbon in the refining process to reduce the effect of carbon matching on molten steel hydrogenation. The production method can effectively control hydrogen addition in production process, reduces the hydrogen content in molten steel, makes the hydrogen content in the steel stay in a range of 1 to 3 ppm, reduces casting blank pinhole defects, and improves casting blank yield rate.
Description
Technical field
The invention belongs to converter steeling technology field, particularly relate to the production method of gas content in a kind of effective control Hot Metal in Beam Blank.
Background technology
In steelmaking process, due to the residual quality and performance having a strong impact on steel of hydrogen.In steel, the existence of hydrogen can cause the defect such as white point, laminated fructure, very bad impact is produced on the mechanical characteristic of iron and steel, particularly it can form hole, makes crack more responsive, seriously reduces the mechanical properties such as the intensity of steel, plasticity, fatigue lifetime and impelling strength.Show according to relevant research, as long as hydrogen richness is lower than 2.0 × 10 in steel
-6just do not occur white point, but along with the sharply reduction of sulphur content in steel, the susceptibility that steel produce white point sharply raises.Avoid and control each production process increasing the important means that hydrogen is raising steel product quality.In prior art, the vacuum-treat of general employing ladle comes Dehydrogenation of Molten Steel, see people such as C.II. Jin Qinke, adopts the state of arts of ladle vacuum processing of liquid steel device dehydrogenation, heavy steel technology, the 50th volume the 2nd phase in 2007.
CN1030793A provides a kind of dehydrogenation method of molten steel and blowing device thereof.The Dehydroepiandrosterone derivative of molten steel adopts the mixture of tetracol phenixin and argon gas, and this mixture adopts the blowing device be made up of the capstan, mixing duct etc. of pressurized tank, buffer tank and connection two tanks to be blown among molten steel, there is dehydrogenation effective, the features such as the temperature head before and after molten steel process is little, the treatment time is short, the present invention is to deoxidation all right while dehydrogenating molten steel.CN102465193A(CN201010545511.3) method of a kind of low carbon stainless steel dehydrogenation in refining furnace, comprise carbon deoxidation under vacuo and strong mixing dehydrogenation under vacuo after reducing, its steps characteristic: the first step, molten steel process early stage, under condition of high vacuum degree, utilize high-carbon deoxidation boiling dehydrogenation molten steel to be not more than 6ppm at VOD refining furnace initial hydrogen content, carbon content is 0.25-0.35%, under vacuum tightness is not more than 3 × 102Pa condition, carbon deoxidation boiling time 15-20min; Under condition of high vacuum degree, utilize steel ladle bottom argon blowing strong mixing dehydrogenation after reducing material all adds 2min after second step, reduction, under vacuum tightness is not more than 3 × 102Pa condition, steel ladle bottom argon blowing gas agitating, argon gas intensity is not less than 12L/min.t, stirs dehydrogenation 16-20min.The present invention makes hydrogen richness in stainless steel all take off 1.5ppm-0.5ppm by initial 2-6ppm, reaches the requirement of low carbon stainless steel to hydrogen richness.
For the production of Hot Metal in Beam Blank, require more strict to hydrogen richness in molten steel during smelting.When rainy season set, small pore is easily had to occur below Hot Metal in Beam Blank casting billet surface or surface, i.e. so-called subcutaneous pin hole.Research shows that existing Hot Metal in Beam Blank controlling of production process is stablized by analysis, and this type of defect does not all appear in other seasons, therefore can determine that the raw material moisture height caused rainy season is the major cause causing subcutaneous pin hole.Under usual state, summer rainwater increases, and atmospheric moisture increases, and part raw material transport and storage cycle longer, raw material moisture is generally higher, causes molten steel hydrogen content higher, is up to 12ppm.In molten steel casting process, in steel, hydrogen atom can be combined into hydrogen molecule and discharges from molten steel, if can not be discharged by gas in steel in time in casting cycle, strand will produce needle pore defect.There is the continuously cast bloom of needle pore defect on surface due to easily oxidized in the operation of rolling, forms surface crack.After the quality of special-shaped billet continuous casting machine and other slab caster strands being contrasted, find that slab caster slab quality is stablized under identical process regulation, finds no hypodermic needle hole defect, but special-shaped billet continuous casting machine slab quality is difficult to control.Not yet find that the production method effectively controlling gas content in Hot Metal in Beam Blank is openly reported at present.
Summary of the invention
For the deficiencies in the prior art, the invention provides the production method of gas content in a kind of effective control Hot Metal in Beam Blank.Method of the present invention while gas content, can also effectively reduce the foreign impurity amount of bringing into, improve Molten Steel Cleanliness in effective control Hot Metal in Beam Blank.
Term illustrates:
Blowing: be point to the molten metal of melting to be blown into oxygen, the impurity oxygen formation gas in molten metal is overflowed, or the oxidizing semlting process becoming that oxide compound slag making carries out.
Rifle position in converter steelmaking process refers to the distance of oxygen rifle head from liquid level.Its mid-early stage rifle position, process rifle position, terminal rifle position correspond to the slagformation period (I phase) of smelting process respectively, carbon period (II phase), decarburizing reaction proceed the stage (III phase), see Fig. 1.
Technical scheme of the present invention is as follows:
In effective control Hot Metal in Beam Blank, a production method for gas content, comprises raw materials pretreatment, converter smelting, deoxidation alloying, refining procedure, and its step is as follows:
(1) production raw material keeps dry materials, and method is as follows:
1) alloy raw material enters roasting kiln and carries out high bake before entering bakery, and storing temperature reaches 300-400 DEG C;
2) for lime moisture-sensitive characteristic, take circulation material-uploading style, avoid long storage time in feed bin, resting period is less than 24 hours;
3) enter stove steel scrap and take feed postition in advance, utilize in-furnace temperature to toast steel scrap, baking time 2 ~ 5 minutes;
4) rest materials, comprises coverter pig synthetic slag, carburelant, refining rice husk, carburelant, protective slag for continuous casting, and use after all entering bakery baking, bakery temperature is 50 ~ 70 DEG C.
(2) converter steelmaking process controls
1) slag charge controls: adopt slag charge to add reach, head criticize that lime adding amount is whole amount of lime 70 ~ 80%, rhombspar full dose adds, and Sinter Ore Control is built in 2.0-3.0t/ stove; Before 3 ~ 4 minutes, slag charge was all added before converter smelting endpoint;
2) rifle position controls: early stage, 1.80-1.90m was brought up to by 1.70-1.80m in rifle position, on average improved 100-200mm; Process rifle position keeps 1.55m, and terminal rifle position keeps 1.1m, and ensure that scorification is saturating in earlier stage, finishing slagization is good, and process evenly heats up, terminal uniform composition;
3) oxygen pressure-controlled: early stage and process oxygen pressure bring up to 0.85MPa by the 0.83MPa of existing technique, and terminal oxygen pressure brings up to 0.88MPa by the 0.85MPa of existing technique.
According to the present invention, converter smelting adds steel scrap in first 2 minutes, and baking time was blended into molten iron after 2 ~ 5 minutes, normally smelted.
According to the present invention, within before converter smelting endpoint 3 ~ 4 minutes, do not allow to add any slag material and slag and temperature are adjusted.
According to the present invention, preferably, during described (2) converter steelmaking process controls, average every stove steel duration of blast be 16 points 30 seconds, the last batch of slag charge joining day advances to blowing 10 ~ 12 timesharing.
Deoxidation alloying operation after converter smelting is by prior art.Step (3) deoxidation alloying operation, preferably, alloy molten steel go out to 1/4 time start to add, add when 3/4, evenly add.Described alloy is Si-Ca-Ba, silicomanganese and/or high manganese.
Method of the present invention also comprises step (4) converter slag upgrading operation, preferred according to the present invention, move after converter slag upgrading: synthetic slag adds at the top of the slag after putting steel, and uniform fold is on slag surface, slag is utilized to carry out high bake to synthetic slag, to reduce moisture and contained crystal water in synthetic slag.By existing technique synthetic slag be put in steel process add change into put steel after add at the top of the slag.
According to method of the present invention, in step (5) refining procedure, preferably, the electrode powder carburetting adopting carbon content >=98.0% is joined in carbon in refining.The carburelant carbon dust of joining in carbon operation by existing refining changes electrode powder into, and the moisture in steel stream brought into by minimizing carburelant.
Technical characterstic of the present invention and excellent results as follows:
Raw material of the present invention keeps dry and refers to that production process raw material used all keeps dry, and lime transport must adopt sealing vehicle, recycles, avoids long storage time; After steel is put in converter, slag modification synthetic slag has to pass through baking and can use; Alloy and reductor etc. also have to pass through baking and can use.From raw material, effective control process increases hydrogen amount.
First the present invention is optimized the rifle position in converter steelmaking process, oxygen pressure and slag charge joining day and pattern, optimizes converter feed pattern, slag charge is added reach, adds 60% of whole amount of lime bring up to 80% by conventional art head batch of material; Avoid terminal first 3 minutes feeding operation; Early stage, 1.80-1.90m was brought up to by 1.70-1.80m in rifle position; Process oxygen pressure brings up to 0.85MPa by the 0.83MPa of existing technique; Last batch of material joining day advanceed to before 12 points.
The present invention moves optimization after carrying out converter slag upgrading, and namely converter adds synthetic slag at the top of the slag after putting steel, utilizes slag to carry out ultrahigh-temperature baking to synthetic slag, and maximum limitation reduces moisture and contained crystal water in synthetic slag.And the original slag modification technique employing of converter adds synthetic slag mode with steel stream, object strengthens synthetic slag fusing, shortcoming is: synthetic slag easily made moist in rainy season, and contained crystal water cannot be undertaken discharging (conventional bakery temperature is generally 50-70 DEG C) by typical baking temperatures, steel quality is vulnerable to moisture effects in synthetic slag.
The present invention joins carbon process optimization to refining, changes electrode powder into by original carburelant carbon dust.Refining routine is joined carbon and is all adopted packed carbon dust to add with steel stream, it is not enough, and place is when carbon dust moisture content is higher, it is more to add carbon dust, molten steel hydrogen richness is just relatively higher, and adopt electrode powder to join carbon, when add-on is identical, electrode powder water content wants relative much less, and difference of them is mainly that carbon content is different, carbon dust carbon content >=90.31%, electrode powder carbon content >=98.0%.
The present invention effectively avoids and control process molten steel hydrogenation from each production process.Under the prerequisite keeping raw material drying, by optimizing converter smelting, refining production technique, avoid molten steel hydrogenation in production process, reduce molten steel H content, make hydrogen richness in steel be stabilized between 1-3ppm, decrease strand needle pore defect, improve strand lumber recovery.The inventive method also increases substantially Hot Metal in Beam Blank cleanliness factor, avoids the potential impact that it produces Hot Metal in Beam Blank surface crack, improves slab quality qualification rate.
Accompanying drawing explanation
Fig. 1 is decarbonization rate and duration of blast graph of a relation.Its mid-early stage (first stage) mainly slagformation period.Because to enter stove molten iron temperature lower, silicone content is higher, is oxidized to master with silicon, and decarburizing reaction is suppressed.Silicon oxidation speed is slack-off soon again, and decarbonization rate is by by accelerating slowly, finally reaches maximum value.Mid-term (second stage) mainly carbon period.Along with liquid steel temperature rises, the carbon in molten steel transfers to seed region with very big speed, and the oxygen of supply almost 100% is consumed in decarburization, and therefore decarbonization rate remains highest level, is almost definite value.Later stage (third stage) decarburizing reaction proceeds, but the concentration of carbon in molten steel is very low, and decarbonization rate constantly declines along with the minimizing of carbon content in steel.Early stage rifle position, process rifle position, terminal rifle position be corresponding with 3 periods of blowing in Fig. 1 respectively.
Embodiment
Below in conjunction with embodiment, the present invention will be further described, but be not limited thereto.
In effective control Hot Metal in Beam Blank, a production method for gas content, comprises the operations such as raw materials pretreatment, converter smelting, deoxidation alloying, refining.Do not limit in detail all by prior art.Wherein converter tonnage is 120 tons.
Embodiment 1: smelt Q235B steel
(1) raw material workshop strength imparting material management and control, ensures that factory supplies must keep dry.Its major measure is as follows: 1) alloy material needs advanced roasting kiln to carry out high bake before entering bakery, storing temperature 300-400 DEG C; 2) lime moisture-sensitive, takes circulation material-uploading style, and in feed bin, resting period is less than 24 hours; 3) enter stove steel scrap and take feed postition in advance, utilize in-furnace temperature to toast steel scrap, baking time 4 minutes; 4) rest materials, comprises coverter pig synthetic slag, carburelant, refining rice husk, carburelant, protective slag for continuous casting etc., all needs to use into after bakery baking, and bakery temperature reaches 55-65 DEG C.(2) converter smelting adds steel scrap in first 2 minutes, is blended into molten iron afterwards, normally smelts, in earlier stage rifle position 1.80-1.90m, process rifle position 1.55m, terminal rifle position 1.10m, head batch lime adds 80% of whole amount of lime, whole rhombspar, 2.5t agglomerate, average every stove steel duration of blast be 16 points 30 seconds, last batch of material joining day is when being blowing 11 points and 30 seconds, early stage, oxygen pressed 0.85MPa, process oxygen pressure 0.85MPa, terminal oxygen pressure 0.88MPa; (3) when putting steel to 1/4, start evenly add 380Kg Si-Ca-Ba, 300Kg silicomanganese, 350Kg high manganese, to 3/4 time add; (4) enter LF refining, Argon stirs 2-3 minute, rear thermometric 1575 DEG C, determine oxygen 38ppm, determine hydrogen 1.8ppm, sampling analysis C:0.13%, Si:0.18%, Mn:0.50%, P:0.019%, S:0.008%, C comparatively prescribed value is low by 0.02%, and with addition of the electrode powder 32Kg of carbon content 98.5%, other operation processes routinely, comprise energising to heat up, residue adjustment etc., thermometric 1580 DEG C before departures, determines oxygen 2ppm, determine hydrogen 2.2ppm, sampling analysis C:0.16%, Si:0.18%, Mn:0.51%, P:0.020%, S:0.006%.
Embodiment 2: smelt steel grade Q235B
Adopt the same processing method of embodiment 1, difference is: in step (4), refining is entered the station hydrogen 2.0ppm, departures hydrogen 2.4ppm.
Embodiment 3:
Smelt steel grade Q235B and processing method with embodiment 1, difference is: refining is entered the station hydrogen 2.0ppm, departures hydrogen 2.3ppm.
Below the example smelting Q235B steel by existing traditional technology, for comparative example.
Comparative example 1:
When smelting Q235B by traditional technology, a) raw material keeps dry materials; B) add steel scrap before converter smelting, be blended into molten iron afterwards, normally smelt, in earlier stage rifle position 1.70-1.80m, process rifle position 1.55m, terminal rifle position 1.10m, head criticize that lime adds whole amount of lime 80%, whole rhombspar, 2.0t agglomerate, last batch of material joining day be 14 points 40 seconds, early stage oxygen pressure 0.83MPa, process oxygen pressure 0.83MPa, terminal oxygen pressure 0.85MPa; When c) putting steel to 1/4, start evenly add 380Kg Si-Ca-Ba, 280Kg silicomanganese, 350Kg high manganese, to 3/4 time add; D) enter LF refining, Argon stirs 2-3 minute, and rear thermometric 1570 DEG C, determines oxygen 40ppm, determine hydrogen 3.0ppm, sampling analysis C:0.12%, Si:0.17%, Mn:0.47%, P:0.020%, S:0.008%, C comparatively prescribed value are low by 0.03%, with addition of carbon dust 48Kg, other operation processes routinely, comprises energising and heats up, residue adjustment etc., thermometric 1578 DEG C before departures, determine oxygen 4ppm, determine hydrogen 3.5ppm, sampling analysis C:0.16%, Si:0.17%, Mn:0.48%, P:0.021%, S:0.006%.
Comparative example 2:
As comparative example 1, difference is: refining is entered the station hydrogen 3.6ppm, departures hydrogen 4.5ppm.
Comparative example 3:
As comparative example 1, difference is: refining is entered the station hydrogen 3.8ppm, departures hydrogen 4.6ppm.
Learnt by refining procedure dynamic monitoring molten steel hydrogen richness: adopt traditional technology, molten steel enters the station hydrogen richness average control at more than 3.5ppm, departures hydrogen average control is in more than 4.5ppm (as comparative example 1 ~ 3); Adopt present invention process, molten steel enters the station hydrogen richness average control at about 2.0ppm, sets off hydrogen average control within 2.5ppm, as the embodiment of the present invention 1 ~ 3.
Claims (1)
1. control a production method for gas content in Hot Metal in Beam Blank, comprise raw materials pretreatment, converter smelting, deoxidation alloying, refining procedure, step is as follows:
(1) production raw material keeps dry materials, and method is as follows:
1) alloy raw material enters roasting kiln and carries out high bake before entering bakery, and storing temperature reaches 300-400 DEG C;
2) for lime moisture-sensitive characteristic, take circulation material-uploading style, avoid long storage time in feed bin, resting period is less than 24 hours;
3) enter stove steel scrap and take feed postition in advance, utilize in-furnace temperature to toast steel scrap, baking time 2 ~ 5 minutes;
4) rest materials, comprises coverter pig synthetic slag, carburelant, refining rice husk, protective slag for continuous casting, and use after all entering bakery baking, bakery temperature is 50 ~ 70 DEG C;
(2) converter steelmaking process controls
1) slag charge controls: adopt slag charge to add reach, head criticize that lime adding amount is whole amount of lime 70 ~ 80%, rhombspar full dose adds, and Sinter Ore Control is built in 2.0-3.0t/ stove; Before 3 ~ 4 minutes, slag charge was all added before converter smelting endpoint;
2) rifle position controls: early stage, 1.80-1.90m was brought up to by prior art 1.70-1.80m in rifle position, on average improved 100-200mm, and process rifle position keeps 1.55m, terminal rifle position keeps 1.1m, and ensure that scorification is saturating in earlier stage, finishing slagization is good, process evenly heats up, terminal uniform composition;
3) oxygen pressure-controlled: early stage and process oxygen pressure bring up to 0.85MPa by prior art 0.83MPa, and terminal oxygen pressure brings up to 0.88 MPa by prior art 0.85 MPa;
(3) move after converter slag upgrading: synthetic slag adds at the top of the slag after putting steel, and uniform fold is on slag surface, utilizes slag to carry out high bake to synthetic slag, to reduce moisture and contained crystal water in synthetic slag;
(4), in refining procedure, the electrode powder carburetting of carbon content >=98.0% is adopted.
2. the production method controlling gas content in Hot Metal in Beam Blank as claimed in claim 1, it is characterized in that, converter smelting adds steel scrap in first 2 minutes, and baking time was blended into molten iron after 2 ~ 5 minutes, normally smelted.
3. the as claimed in claim 1 production method controlling gas content in Hot Metal in Beam Blank, is characterized in that, alloy molten steel go out to 1/4 time start to add, add when 3/4, evenly add.
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| CN103741007B (en) * | 2013-12-23 | 2015-08-19 | 武钢集团昆明钢铁股份有限公司 | A kind of production method reducing gas content in carbon aluminium-killed steel |
| CN105441636A (en) * | 2015-11-16 | 2016-03-30 | 山东钢铁股份有限公司 | Method for controlling added hydrogen in steelmaking process |
| CN105969932B (en) * | 2016-06-30 | 2018-04-06 | 山东钢铁股份有限公司 | A kind of method for making steel control hydrogen |
| CN113435114B (en) * | 2021-06-23 | 2022-11-22 | 马鞍山钢铁股份有限公司 | Method for accurately controlling nitrogen content of steel grade of CV-RH-CC process route |
| CN115283633A (en) * | 2022-08-04 | 2022-11-04 | 广西钢铁集团有限公司 | Method for preventing Q235B slab from generating bubbles |
| CN117305536B (en) * | 2023-09-28 | 2024-06-07 | 河北普阳钢铁有限公司 | Method for producing ultralow hydrogen content steel under non-vacuum condition |
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| US3635696A (en) * | 1968-05-21 | 1972-01-18 | Finkl & Sons Co | Treatment of molten metal using arc heat and vacuum |
| US8097065B2 (en) * | 2006-10-04 | 2012-01-17 | Nu-Iron Technology, Llc | System and method for producing metallic iron |
| CN102329913A (en) * | 2011-07-08 | 2012-01-25 | 南阳汉冶特钢有限公司 | Method for reducing micro cracks on surface of steel plate |
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