CN104263876B - A kind of nitrogen pick-up increasing manganese method of producing for high-strength steel - Google Patents
A kind of nitrogen pick-up increasing manganese method of producing for high-strength steel Download PDFInfo
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Abstract
The present invention relates to a kind of nitrogen pick-up increasing manganese method of producing for high-strength steel.Employing feeds nitrogenized manganese cored-wire at LF stove refining procedure and carries out nitrogen pick-up, increases manganese, described nitrogenized manganese cored-wire diameter 12 ~ 14mm, the core grain weight 450 ~ 500g/m of nitrogenized manganese cored-wire in molten steel, and tare weight 125 ~ 175g/m mass ratio forms; Described nitrogenized manganese cored-wire, by molten steel feeding per ton 280 ~ 300 meters of nitrogenized manganese cored-wires, realizes complete nitrogen pick-up, and molten steel nitrogen pick-up stability contorting is at 50-60ppm, and complete part while realizing complete nitrogen pick-up and increase manganese, increasing manganese amount is 0.09 ~ 0.10%.Do not need nitrogen blowing in each operation of the present invention, realize nitrogen increased amount one step controlled, molten steel nitrogen pick-up can be completed while refining section increases manganese, improve molten steel nitrogen recovery rate.
Description
Technical field
The present invention relates to a kind of nitrogen pick-up increasing manganese method of producing for high-strength steel, belong to ferrous metallurgy steelmaking technical field.
Background technology
Ti, V, Nb micro-alloying technology, worldwide be widely used with its significant economic technique superiority, and nitrogen can improve intensity and the plasticity of steel, expand austenitic area, crystal grain thinning, improve its processing characteristics, therefore, adopt V-n Microalloying Technology, high strength is obtained under low content of vanadium, the obvious consumption saving vanadium, reduces the cost of steel, especially embodies obviously in high-strength steel.CN102732686A discloses a kind of method adopting two step vacuum methodes to produce v n micro alloying high-strength steel, vacuum-treat operation is increased in the smelting procedure of v n micro alloying high-strength steel, dehydrogenation nitrogen pick-up is carried out to the molten steel after the adjustment of vanadium nitrogen content, described vacuum-treat operation takes omnidistance ladle bottom blowing nitrogen process, described vacuum-treat operation adopts the function of two step vacuum metling factures to vacuum metling process effectively to decompose, to reach the effect that nitrogen is protected in dehydrogenation.Adopt method of the present invention, in the steel smelted, not only hydrogen richness can reach below 1.5ppm, nitrogen content can be controlled in 120 ~ 220ppm, total oxygen can be controlled in below 20ppm, and can more than 98% be reached in rolling reduction thickness specification less than normal in the thick steel plates extension property qualification rate of more than 40mm, improve the over-all properties of VN alloy steel grade, reduce VN alloy consumption, improve yield of steel plate, reduce cost.CN103952511A discloses a kind of high-strength steel nitrogen content of molten steel control method, molten steel nitrogen pick-up technique in smelting high-strength steel process is carried out converter smelting process, the optimization of refining furnace smelting technology and continuous casting protective casting technique three phases, by deoxidation slag making, the improvement of alloying order, control three stages nitrogen pick-up node, after realizing converter tapping, nitrogen content of molten steel controls within 0.0030%, LF+RH process molten steel nitrogen pick-up stability contorting is within 0.0010%, continuous casting working procedure molten steel nitrogen pick-up stability contorting is within 0.0005%, finally realize Control of Nitrogen Content in high alloy high-strength steel continuously cast bloom within 0.0045%, the method substantially increases strand inside and surface quality.
Result of study shows, V-n Microalloying Technology mainly by the impact on the Precipitation Kinetics of vanadium after nitrogen pick-up in steel, optimizes the precipitation state of vanadium, adds the precipitation strength effect of vanadium, and the effect such as the refined crystalline strengthening effect brought thus, thus improve the performance of steel.In steel, VN alloy method is commonly used in nitrogen pick-up, but there is nitrogen increased amount not enough defect, therefore application nitrogenized manganese cored-wire nitrogen pick-up technique, solves problems.
Summary of the invention
For the deficiencies in the prior art, the invention provides a kind of nitrogen pick-up increasing manganese method of producing for high-strength steel, be mainly applied to nitrogen pick-up technique when combined blown converter and LF refining smelting high-strength steel.The nitrogen pick-up of producing especially for S450J0, Q550D, Q690D high-strength steel increases manganese method.
Term illustrates:
1, high-strength steel, refers to the class steel grade that the ranks such as yield strength in mechanical property, tensile strength, ballistic work are higher, the steel grades such as such as Q550D, Q690D, S450j0, and composition of steel designs by required standard according to steel grade.The present invention does not limit composition of steel.Wherein, the Fe content scope of different steel grade is also slightly different, and such as certain high-strength steel manganese component requirements is at 1.30-1.50%, then its lower limit is about 1.30-1.32%, and middle limit is about 1.40%, and those skilled in the art can determine according to prior art.
2, increasing manganese amount, is massfraction, is after converter is normally tapped in molten steel based on Fe content, then increases the content of manganese.Such as after tapping, molten steel Fe content is 0.12%, and when feeding cored-wire increases manganese amount 0.09 ~ 0.10%, then after feeding cored-wire, molten steel Fe content adds up to 0.21-0.32%.
Technical scheme of the present invention is as follows:
A kind of nitrogen pick-up increasing manganese method of producing for high-strength steel, the technique that high-strength steel is produced comprises hot metal pretreatment, top and bottom combined blown converter smelting, the refining of LF stove, continuous casting working procedure, it is characterized in that, employing feeds nitrogenized manganese cored-wire at LF stove refining procedure and carries out nitrogen pick-up, increases manganese, described nitrogenized manganese cored-wire diameter 12 ~ 14mm, the core grain weight 450 ~ 500g/m of nitrogenized manganese cored-wire in molten steel, tare weight 125 ~ 175g/m mass ratio forms, and foreskin is pure iron skin material; In the core powder of nitrogenized manganese cored-wire, mass percentage content is composed as follows:
Mn >=80%, N >=7%, C≤0.1%, P≤0.03%, Si≤1.0%, S≤0.02%; Each composition sum is 100%;
In the top and bottom combined blown converter of 120 tons, described nitrogenized manganese cored-wire is by 280 ~ 300 meters/stove feeding nitrogenized manganese cored-wire, and realize complete nitrogen pick-up, molten steel nitrogen pick-up stability contorting is at 50-60ppm, complete part while realizing complete nitrogen pick-up and increase manganese, increasing manganese amount is 0.09 ~ 0.10%.Nitrogen blowing is not needed in each operation.
If use the top and bottom combined blown converter of other tonnages instead, can converse the consumption of the nitrogenized manganese cored-wire of every stove molten steel in proportion, those skilled in the art's use change of variable on this basis, all in protection scope of the present invention.
According to method of the present invention, preferably, the mode that described refining procedure feeds nitrogenized manganese cored-wire in molten steel is: first Argon slag after ladle enters the station, then disposable feeding nitrogenized manganese cored-wire.
According to method of the present invention, preferably, in the core powder of nitrogenized manganese cored-wire, mass percentage content is composed as follows: Mn:80-82.5%, N:7-7.5%, C≤0.1%, P≤0.03%, Si≤1.0%, S≤0.02%; Each composition sum is 100%.
According to method of the present invention, preferably, before converter tapping, calculate according to refining procedure nitrogenized manganese cored-wire feed quantity and increase manganese amount, during alloying, molten steel Fe content is controlled at composition lower limit.
According to method of the present invention, preferably, refining procedure, according to molten steel just sample ingredient, also needs, with addition of a certain amount of mid-carbon fe-mn, molten steel Fe content to be assigned to middle limit, completes and increases manganese operation.Mid-carbon fe-mn is a kind of steel-making alloy, and effect is adjustment molten steel manganese element content.Refining procedure, except feeding nitrogenized manganese cored-wire, if manganese element is still inadequate, needs to add mid-carbon fe-mn; Particularly nitrogen manganese line feed quantity has strict restriction, disposablely can not add too much, otherwise can affect steel quality.
According to method of the present invention, preferably, described nitrogenized manganese cored-wire feeds in molten steel by feeding wire machine, wire-feeding velocity 2.8-3.5 meter per second.Then the excessive velocities of feeding cored-wire can make molten steel liquefy has strong reaction, and nitrogen recovery just greatly reduces; And speed is crossed the pressure that slowly cored-wire can be made to can not meet molten steel and made it to occur residue, alloy recovery can decline equally, and the speed that therefore must control cored-wire feeding just can be guaranteed to improve nitrogen recovery in certain limit.
According to the present invention, a kind of preferred scheme is, a kind of nitrogen pick-up increasing manganese method of producing for high-strength steel, comprises step as follows:
(1), in top and bottom combined blown converter smelting operation, before converter tapping, calculate according to refining procedure nitrogenized manganese cored-wire feed quantity and increase manganese amount, during alloying, molten steel Fe content is controlled at composition lower limit; This lower limit is determined according to concrete steel grade of producing.
(2) according to high strength steel grade composition of steel, in molten steel, feed 280 ~ 300 meters of nitrogenized manganese cored-wires at refining procedure to carry out nitrogen pick-up, increase manganese, increase manganese amount by 0.09 ~ 0.10%, part completes nitrogen pick-up operation while increasing manganese, molten steel nitrogen pick-up stability contorting is at 50-60ppm;
(3) after feeding nitrogenized manganese cored-wire in refining procedure, according to molten steel, just sample ingredient is quantitative with addition of mid-carbon fe-mn again, is assigned in composition by molten steel Fe content and limits, and completes and increases manganese operation.
Do not add in this specification sheets and in detail to limit, all by state of the art.
According to the traditional representation mode of this area, nitrogen manganese cored-wire physical and chemical index of the present invention sees the following form 1:
Table 1
Beneficial effect of the present invention:
1, the present invention adopts nitrogenized manganese cored-wire to compare nitrogen pick-up in prior art high-pressure bottom nitrogen flushing method steel, and in alloy, the recovery rate of nitrogen is high and stable.Do not need nitrogen blowing in each operation of the present invention, realize nitrogen increased amount one step controlled.On the other hand, comparatively VN alloy is cheap for nitrogenized manganese cored-wire.
2, nitrogen pick-up of the present invention, the design of increasing preparation of manganese can complete molten steel nitrogen pick-up while refining section increases manganese, improve molten steel nitrogen recovery rate.The average recovery rate of nitrogen improves about 90%; The low multiple quality producing steel billet is good; The indices of the mechanical property of steel not only meets the requirement of steel grade, and its intensity, impact value improve all relatively.
3, the present invention adopts nitrogenized manganese cored-wire due to available feeding wire machine line feeding, relatively prior art nitrogen silicomanganese instead of and manually adds bulk alloy, thus reduce labor strength reduction, operating environment also improves, adopt wire injection procedure simultaneously, nitrogen, manganese scaling loss in molten steel reduces, and element recovery rate is improved.
4, the present invention adopts feeding nitrogenized manganese cored-wire to carry out nitrogen pick-up, increase manganese, promote that V separates out crystal grain thinning simultaneously by nitrogen pick-up, with precipitation strength and refined crystalline strengthening for mainly to strengthen means, can obtain that yield strength is greater than 500MPa, tensile strength is greater than 750MPa, plasticity and the excellent high-strength vehicle structural steel of cold-bending property that breaking elongation of having no progeny is greater than 20%.
The present invention can meet the molten steel nitrogen pick-up requirement when refining procedure produces high-strength steel.This kind of process for making achieves molten steel nitrogen pick-up to improve the object of steel strength.
Embodiment
Below in conjunction with embodiment, the present invention will be further described, but be not limited thereto.Percentage composition in embodiment is massfraction, except special instruction.The nitrogenized manganese Determining Composition of Cored Wire used in embodiment is as following table 2:
Table 2
Embodiment 1:S450J0 steel grade, 120 tons of combined blown converters
Adopt hot metal pretreatment → top and bottom combined blown converter smelting → LF stove refining → continuous casting process to produce S450J0 steel, wherein adopt method of the present invention to carry out nitrogen pick-up, increase manganese, other operations are all by prior art.Comprise the steps:
A. adopt pretreated molten iron, various alloy should toast drying before using;
B. converter terminal control objectives: [C] >=0.08%, [P]≤0.025%, T >=1650 DEG C; Adopt slag-stopping tapping, adopt silicomanganese, ferrosilicon and VN alloy, controlled by molten steel Fe content during alloying at composition lower limit (S450J0 steel manganese composition lower limit 1.30%), Si-Ca-Ba final deoxygenation, add-on 2.0kg/t steel, adds lime block 600kg.
C. after ladle enters the station, (before getting first composition sample) is first carried out nitrogen pick-up by every stove feeding 290 ± 5 meters of nitrogenized manganese cored-wires, is increased manganese in molten steel, increases manganese amount by 0.09 ~ 0.10%.Wire-feeding velocity 3.0 meter per second.Refining white slag operates, and adopt Si-Ca-Ba deoxidation slag making, add-on is determined according to actual slag situation, and latter stage is fed calcium iron wire 200 meters, wire-feeding velocity 3.0 meter per second in refining.After line feeding, soft argon blowing time is not less than 10 minutes.
Complete in refining procedure after feeding nitrogenized manganese cored-wire, according to molten steel, just sample ingredient is quantitative with addition of mid-carbon fe-mn again, is assigned to by molten steel Fe content in composition and limits (limitting 1.40% in S450J0), completes and increases manganese operation.
D. continuous casting steel superheating temperature is less than 30 DEG C, and casting speed control is at 0.8-0.9m/min.
By above-mentioned embodiment, produce S450J0 steel under can making molten iron pre-desulfurization-top and bottom combined blown converter-LF refining-continuous casting process condition, the mass percent of nitrogen in steel can reach (50 ~ 70) × 10
-6.Gained S450J0 Steel Bar yield strength 500MPa, tensile strength 760MPa, breaking elongation 22% of having no progeny.
Embodiment 2:Q550D, 120 tons of combined blown converters
The Q550D steel adopting hot metal pretreatment → top and bottom combined blown converter smelting → LF stove refining → continuous casting process to produce, wherein adopt method of the present invention to carry out nitrogen pick-up, increase manganese, other operations are all by prior art.Carry out as follows:
A. adopt pretreated molten iron, various alloy should toast drying before using;
B. converter terminal control objectives: [C] >=0.06%, [P]≤0.020%, T >=1640 DEG C; Adopt slag-stopping tapping, adopt silicomanganese, ferro-niobium, ferrochrome, aluminium ferromanganese final deoxygenation, add-on 3.5kg/t steel, adds lime block 600kg.During alloying, molten steel Fe content is controlled composition lower limit (the manganese lower limit of Q550D is 1.20%).
C. after ladle enters the station, (before getting first composition sample) is first carried out nitrogen pick-up by every stove feeding 295 ± 5 meters of nitrogenized manganese cored-wires, is increased manganese in molten steel, increases manganese amount by 0.09 ~ 0.10%.Wire-feeding velocity 3.1 meter per second.Refining white slag operates, and adopt aluminum shot deoxidation slag making, add-on is determined according to actual slag situation, and latter stage is fed calcium iron wire 350 meters, wire-feeding velocity 3.1 meter per second in refining.After line feeding, soft argon blowing time is not less than 10 minutes.Complete in refining procedure after feeding nitrogenized manganese cored-wire, according to molten steel, just sample ingredient is quantitative with addition of mid-carbon fe-mn again, is assigned to by molten steel Fe content in composition and limits (limitting 1.30% in Q550D), completes and increases manganese operation.
D. continuous casting steel superheating temperature is less than 30 DEG C, and casting speed control is at 1.3-1.4m/min.
Produce Q550D steel by aforesaid method, the mass percent of nitrogen in steel can reach (60 ~ 80) × 10-6.Gained Q550D steel board yield strength 600MPa, tensile strength 820MPa, breaking elongation 21% of having no progeny.
Claims (5)
1. a nitrogen pick-up increasing manganese method of producing for high-strength steel, the technique that high-strength steel is produced comprises hot metal pretreatment, top and bottom combined blown converter smelting, the refining of LF stove, continuous casting working procedure, it is characterized in that, employing feeds nitrogenized manganese cored-wire at LF stove refining procedure and carries out nitrogen pick-up, increases manganese, described nitrogenized manganese cored-wire diameter 12 ~ 14mm, the core grain weight 450 ~ 500g/m of nitrogenized manganese cored-wire in molten steel, tare weight 125 ~ 175g/m, foreskin is pure iron skin material; In the core powder of nitrogenized manganese cored-wire, mass percentage content is composed as follows:
Mn >=80%, N >=7%, C≤0.1%, P≤0.03%, Si≤1.0%, S≤0.02%; Each composition sum is 100%;
In the top and bottom combined blown converter of 120 tons, by 280 ~ 300 meters/stove feeding nitrogenized manganese cored-wire, realize complete nitrogen pick-up, molten steel nitrogen pick-up stability contorting is at 50-60ppm, and complete part while realizing complete nitrogen pick-up and increase manganese, increasing manganese amount is 0.09 ~ 0.10%.
2. nitrogen pick-up according to claim 1 increases manganese method, it is characterized in that the mode that described refining procedure feeds nitrogenized manganese cored-wire in molten steel is: first Argon slag after ladle enters the station, then disposable feeding nitrogenized manganese cored-wire.
3. nitrogen pick-up according to claim 1 increases manganese method, before it is characterized in that converter tapping, calculates and increases manganese amount, during alloying control molten steel Fe content at composition lower limit according to refining procedure nitrogenized manganese cored-wire feed quantity.
4. nitrogen pick-up according to claim 1 increases manganese method, it is characterized in that refining procedure is according to molten steel just sample ingredient, also needs, with addition of a certain amount of mid-carbon fe-mn, molten steel Fe content to be assigned to middle limit, completes and increase manganese operation.
5. nitrogen pick-up according to claim 1 increases manganese method, it is characterized in that described nitrogenized manganese cored-wire is by feeding wire machine feeding molten steel, wire-feeding velocity 2.8-3.5 meter per second.
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| CN107747047A (en) * | 2017-11-30 | 2018-03-02 | 攀钢集团攀枝花钢铁研究院有限公司 | Steel Bar and its production method are built containing Nb, Cr microalloy |
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| CN110438292A (en) * | 2019-08-05 | 2019-11-12 | 凌源钢铁股份有限公司 | A kind of method of molten steel nitrogen pick-up in process for making |
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| US3356493A (en) * | 1964-01-22 | 1967-12-05 | Electro Chimie Metal | Alloys for nitriding steel and method of nitriding steel |
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