CN103695600B - Low-cost production method of boracic low-alloy-structured steel sheet billet - Google Patents
Low-cost production method of boracic low-alloy-structured steel sheet billet Download PDFInfo
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Abstract
The invention provides a low-cost production method of a boracic low-alloy-structured steel sheet billet. The method comprises the following steps: (1) pretreating molten iron to ensure that the content of S (sulfur) in the molten iron is less than or equal to 0.005% and the bright surface with slag removal after desulfuration is greater than or equal to 85%; (2) performing tapping on steel with the roughing slag amount less than 4kg/t; (3) throwing 30kg of carbon powder for preliminary dexidation after the steel ladle bottom of the molten steel appears; adding 3.5kg/t of silicon iron of the steel when the steel tapping quantity reaches 1/3; immediately throwing a carburant after the addition of the silicon iron, wherein the adding amount of the carburant is based on the C (carbon) at a final point and the C increasing amount in alloy, namely, 35kg of carburant is added when 0.01% of carbon is increased in each time; and immediately adding 7kg/t of silicon manganese after the addition of the carburant; and (4) feeding different aluminum wires into the steel ladle according to the different oxygen contents of the molten steel after the steel ladle enters an alloy trimming station, wherein generally, the feeding quantity of the aluminum wires is less than 0.15kg/t of steel; and adding less than 0.15kg/t of ferroboron of the steel after the feeding of the aluminum wires, wherein performing intense agitation by adopting a top gun in a bottom argon blowing mode and then performing weak agitation during the alloying and processes under the condition that the total agitation time is greater than 10 minutes.
Description
Technical field
The invention belongs to field of iron and steel smelting, particularly the Low-cost production method of kind of boron-containing low alloy structure iron slab
Background technology
A small amount of boron just effectively can improve the performance of steel, and it is widely used in the production of Q235 level, Q345 level hot-rolled sheet coil and other steel.But in smelting and casting process, mainly there is following problem in boron-containing steel.
One is that Boron contents is unstable.Boron content in steel is lower, and generally at 10 ~ 50ppm, chemical property is comparatively active in addition, has very strong affinity with oxygen, nitrogen, and the rate of recovery stability controlling boron when producing boron-containing steel becomes crucial.Boron-containing steel all adopts LF or vacuum furnace outer refining process to reduce terminal oxygen activity and nitrogen content to improve the recovery rate of boron mostly.The Chinese patent of application number 03134895.5 discloses and a kind ofly to adopt, and " desulfurizing iron is skimmed → top and bottom combined blown converter smelting → ladle deoxidation alloying → steel ladle bottom argon blowing refining, refining terminal target oxygen activity 25 × 10
-6~ 45 × 10
-6→ feed Al, Si-Ca line, boron line → continuous casting " explained hereafter boron steel, the scope 0.005% ~ 0.012% of Boron contents in steel, the recovery rate 40 ~ 50% of boron." steel research " magazine (the 4th phase in 2004, P18-22) reports Shoudu Iron and Steel Co and adopts 80tLD converter → LF stove liquid steel refining, controls the refining oxygen activity that arrives at a station and is less than 20 × 10
-6, (FeO+MnO)≤3.0% in slag → add Al, Ti, boron alloyed → billet continuous casting explained hereafter boron-containing steel, the average recovery rate 60% of B.Application number be 200710049005.3 Chinese patent disclose and a kind of to adopt the method for the explained hereafter boron steel of " converter smelting → ladle pre-deoxidation and refining, ladle final deoxygenation → LF stove refining, deep deoxidation, alloying → continuous casting ", LF refining terminal oxygen activity≤10 × 10
-6, the recovery rate of boron is 69.4 ~ 91.8%.China Patent No. 200810015497 discloses " a kind of vacuum metling boron-containing steel improves and stablizes the method for the boron rate of recovery ", adopts the rate of recovery of this method boron to reach more than 90%.
Two is that boron-containing steel slab easily cracks.In sheet billet continuous casting process, cracking due to the precipitation of boride in steel, needing to clear up strand for eliminating crackle.
Three is that smelting cost is higher.For ensureing the stable of Boron contents, operation adopting LF or vacuum refinement usually, which increases process cost; Deoxidization technique carrys out deoxidation with the reductor such as aluminium, calcium that price is high for master usually, which increases process costs; Slab quality aspect is eliminate the impact of strand crackle, usually will clear up strand, then add the loss of disposal costs and metal charge.
Summary of the invention
For overcoming the technical problem that prior art exists, the invention provides a kind of Low-cost production method of boron-containing low alloy structure iron slab, the method can reduce the crackle of strand, the stability improving Boron contents in steel, reduction production cost, simplify production technique.
For solving the problems of the technologies described above, the present invention is for a kind of Low-cost production method of boron-containing low alloy structure iron slab, comprise hot metal pretreatment, converter smelting, tapping process alloying, alloy fine setting station process, continuous casting working procedure, it is characterized in that, described hot metal pre process procedures is: skim before and after hot metal pretreatment, [S]≤0.005% after control desulfurizing iron, skims bright >=85% after desulfurization; Described converter smelting operation is: converter smelting adopts conventional smelting process, and tapping process strengthens Converter Skimming operation, and the lower quantity of slag is less than 4kg/t steel; Described tapping process alloying step is: molten steel is shown in that bag end defensive position throws carbon dust 30kg pre-deoxidation, tap adds the ferrosilicon of 3.5kg/t steel when reaching 1/3, throwing carburelant is connected immediately after ferrosilicon adds, add-on increases [C] amount according to terminal [C] and alloy, often increase by 0.01% carbon, add carburelant 35Kg, after carburelant adds, add the silicomanganese of 7Kg/t immediately; Described alloy fine setting station treatment process is: after ladle enters alloy fine setting station, the aluminum steel different according to the oxygen level difference feeding of molten steel, common aluminum steel feeding is less than 0.15kg/t steel, feed after aluminum steel terminates and add the ferro-boron being less than 0.15kg/t steel, top rifle and argon bottom-blowing pattern strong stirring is adopted in alloying and process, then weakly stir, total churning time is greater than 10min.
The present invention adopts alloy fine setting station to carry out deoxidation, the alloying of molten steel, be main reductor and alloying element with silicon, manganese, be auxiliary reductor with aluminium deoxidation, without the need to carrying out LF refining or vacuum refinement, reducing the nitrogen content of LF refining process molten steel, reduce, alleviating the slab corner crack that the precipitation because of boron and aluminium causes, without the need to clearing up strand, the hot charging of strand can be realized or directly fill rolling, thus reducing production cost.
Embodiment
Present invention process flow process is hot metal pretreatment → converter → tapping process alloying → alloy fine setting station → continuous casting, elaborates the present invention below for the production method of Q235 level hot-rolled sheet coil boron-containing steel slab.
Q235 level hot-rolled sheet coil boron-containing steel slab of the present invention comprises the chemical composition of following mass percent: C:0.10 ~ 0.25, Si:0.10 ~ 0.40, Mn:0.50 ~ 0.90, P≤0.020, S≤0.015, Als≤0.009, B:0.0008 ~ 0.0030, other is Fe and relict element.
Concrete production method is described as follows:
(1) skim before and after hot metal pretreatment, [S]≤0.005% after control desulfurizing iron, skims bright >=85% after desulfurization.
(2) converter smelting adopts conventional smelting process.
(3) tapping process strengthens Converter Skimming operation, and the lower quantity of slag is less than 4kg/t steel.
(4) tapping process alloying: molten steel is shown in that bag end defensive position throws carbon dust 30kg pre-deoxidation; Tap adds the ferrosilicon of 3.5kg/t steel when reaching 1/3, connect throwing carburelant immediately after ferrosilicon adds, and add-on increases [C] amount according to terminal [C] and alloy: often increase by 0.01% carbon, add carburelant 35Kg; The silicomanganese of 7Kg/t is added immediately after carburelant adds.
(5) alloy fine setting station: after ladle enters alloy fine setting station, the aluminum steel different according to the oxygen level difference feeding of molten steel, common aluminum steel feeding is less than 0.15kg/t steel, feed after aluminum steel terminates and add the ferro-boron being less than 0.15kg/t steel, top rifle and argon bottom-blowing pattern strong stirring is adopted in alloying and process, then weakly stir, total churning time is greater than 10min.
(6) the conventional plate blank continuous casting process of Q235 level steel grade is adopted.
。。。。The recovery rate of boron of the strand adopting aforesaid method to produce is 78.2%, slab flawless defect, can hot-loading and hot-conveying to steel rolling process.
Claims (1)
1. the Low-cost production method of a boron-containing low alloy structure iron slab, comprise hot metal pretreatment, converter smelting, tapping process alloying, alloy fine setting station process, continuous casting working procedure, it is characterized in that, described hot metal pre process procedures is: skim before and after hot metal pretreatment, [S]≤0.005% after control desulfurizing iron, skims bright >=85% after desulfurization; Described converter smelting operation is: converter smelting adopts conventional smelting process, and tapping process strengthens Converter Skimming operation, and the lower quantity of slag is less than 4kg/t steel; Described tapping process alloying step is: molten steel is shown in that bag end defensive position throws carbon dust 30kg pre-deoxidation, tap adds the ferrosilicon of 3.5kg/t steel when reaching 1/3, throwing carburelant is connected immediately after ferrosilicon adds, add-on increases [C] amount according to terminal [C] and alloy, often increase by 0.01% carbon, add carburelant 35Kg, after carburelant adds, add the silicomanganese of 7kg/t steel immediately; Described alloy fine setting station treatment process is: after ladle enters alloy fine setting station, according to the aluminum steel of the oxygen level difference feeding Different Weight of molten steel, aluminum steel feeding is less than 0.15kg/t steel, feed after aluminum steel terminates and add the ferro-boron being less than 0.15kg/t steel, top rifle and argon bottom-blowing pattern strong stirring is adopted in alloying process, then weakly stir, total churning time is greater than 10min.
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| CN105316558B (en) * | 2014-07-01 | 2017-05-03 | 本钢板材股份有限公司 | Preparation method of boron-containing steel preventing casting blank corner cracking |
| CN105803310B (en) * | 2016-03-24 | 2017-10-24 | 攀钢集团攀枝花钢铁研究院有限公司 | A kind of cold rolling light-wall pipe hot rolled strip and its smelting process |
| CN109128074B (en) * | 2018-09-25 | 2020-09-04 | 湖南华菱湘潭钢铁有限公司 | Production method of microalloy steel capable of being hot-fed and hot-charged |
| CN111778448A (en) * | 2020-06-15 | 2020-10-16 | 南京钢铁股份有限公司 | Production method of extremely-low-cost boron-containing thin-specification outlet alloy steel |
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| DE3416952A1 (en) * | 1984-05-08 | 1985-11-14 | Elektroschmelzwerk Kempten GmbH, 8000 München | METHOD FOR PRODUCING STEEL ALLOYED WITH BOR |
| JPH01255644A (en) * | 1988-04-05 | 1989-10-12 | Nkk Corp | Manufacture of iron-boron-silicon alloy |
| CN1309856C (en) * | 2003-09-27 | 2007-04-11 | 首钢总公司 | Method for manufacturing continuous casting low carbon steel containing boron in small square billets |
| CN100519769C (en) * | 2007-04-29 | 2009-07-29 | 攀钢集团攀枝花钢铁研究院 | Boron steel producing converter smelting process |
| CN100500916C (en) * | 2007-10-17 | 2009-06-17 | 莱芜钢铁集团有限公司 | Boron-containing steel and preparation method thereof |
| CN101503746A (en) * | 2009-03-19 | 2009-08-12 | 新余钢铁股份有限公司 | Method for producing boron steel by converter |
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