CN103469104B - A kind of boracic duplex stainless steel and boron alloyed smelting process thereof - Google Patents

A kind of boracic duplex stainless steel and boron alloyed smelting process thereof Download PDF

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CN103469104B
CN103469104B CN201310355277.1A CN201310355277A CN103469104B CN 103469104 B CN103469104 B CN 103469104B CN 201310355277 A CN201310355277 A CN 201310355277A CN 103469104 B CN103469104 B CN 103469104B
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molten steel
steel
slag
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ladle
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CN103469104A (en
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陈兴润
潘吉祥
王建新
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Gansu Jiu Steel Group Hongxing Iron and Steel Co Ltd
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Abstract

The invention discloses a kind of boracic duplex stainless steel and smelting process thereof, boracic duplex stainless steel, according to the chemical composition of mass percent be, C:0.018 ~ 0.025%, Si:0.48 ~ 0.54%, Mn:1.15 ~ 1.20%, P≤0.025%, S≤0.0005%, Cr:22.20 ~ 22.30%, Ni:5.20 ~ 5.25%, Mo:3.08 ~ 3.12%, N:0.174 ~ 0.184%, B:0.0028 ~ 0.0035%, other is Fe and relict element.The boron alloyed smelting process of described boracic duplex stainless steel, skims after comprising AOD refining, AOD tapping, LF refining and continuous casting, in LF refining process, add borax.This smelting process, adds borax under the prerequisite reducing entire oxygen content in the steel content, ensures the acid-soluble boron that stable acquisition is appropriate.The borax added is for containing acidic oxide B 2o 3slag former, borax wide material sources, low price.Production technique is simple and easy, and borax is except as the modification agent of slag, can also complete the alloying of boron.

Description

A kind of boracic duplex stainless steel and boron alloyed smelting process thereof
Technical field
The invention belongs to stainless steel smelting technical field, particularly relate to a kind of boracic duplex stainless steel and boron alloyed smelting process thereof.
Background technology
Boron is the interstitial atom that atomic radius is very little, and boron, in the segregation of duplex stainless steel crystal boundary, can improve the intensity of crystal boundary, improves hot workability.In addition, adding of boron can provide more nucleation site in molten steel solidification process, thus improves the equiaxial crystal ratio of two-phase stainless plate slab.But too much boron adds, easily form the precipitated phase of low melting point at crystal boundary, worsen hot workability.Therefore, in the process of producing duplex stainless steel, it is useful for adding the hot workability of appropriate B to steel.
When adopting AOD converter smelting → LF refinery practice to produce duplex stainless steel, conventional method in AOD tapping process or LF refining process, adds ferro-boron or boron line to complete the alloying of boron.
Patent " a kind of duplex stainless steel and manufacture method thereof " (patent No. ZL200810079771.9, publication number CN101403077, day for announcing 2009.04.08) disclose a kind of duplex stainless steel and manufacture method thereof, when AOD taps, molten steel is poured in baked ladle, when tap reaches 1/3 of total molten steel amount, disposablely in ladle, add ferro-boron 0.4 ~ 0.5kg/t.
Patent " a kind of duplex stainless steel and manufacture method thereof " (patent No. ZL200910046646.2, notification number CN101812647A, day for announcing 2010.08.25) disclose a kind of duplex stainless steel and manufacture method thereof, in ladle or crystallizer, the B of 0 ~ 0.003% is added in the mode of feeding silk.
The technique of existing boron alloyed smelting boracic duplex stainless steel, deficiency be ferro-boron and boron line cost higher, simultaneously complicated operation in the process that adds at ladle or crystallizer of ferro-boron line, easy broken string, in addition the total oxygen content in steel directly affects the rate of recovery of boron, the oxidation that oxygen causes [B], reduces the content of acid-soluble boron in molten steel.Therefore, the method for the boron alloyed smelting boracic duplex stainless steel that exploitation is a kind of easily, raw material sources is extensive, production cost is low, Boron contents is stable is necessary.
Summary of the invention
The object of the present invention is to provide a kind of boracic duplex stainless steel.
For achieving the above object, the technical scheme that the present invention takes is:
A kind of boracic duplex stainless steel, according to mass percent, chemical composition is, C:0.018 ~ 0.025%, Si:0.48 ~ 0.54%, Mn:1.15 ~ 1.20%, P≤0.025%, S≤0.0005%, Cr:22.20 ~ 22.30%, Ni:5.20 ~ 5.25%, Mo:3.08 ~ 3.12%, N:0.174 ~ 0.184%, B:0.0028 ~ 0.0035%, other is Fe and relict element.
According to mass percent, the chemical composition of described boracic duplex stainless steel is, C:0.018%, Si:0.48%, Mn:1.18%, P:0.025%, S:0.0003%, Cr:22.27%, Ni:5.25%, Mo:3.10%, N:0.184%, B:0.0035%, other is Fe and relict element.
According to mass percent, the chemical composition of described boracic duplex stainless steel is, C:0.025%, Si:0.50%, Mn:1.15%, P:0.022%, S:0.0005%, Cr:22.30%, Ni:5.20%, Mo:3.12%, N:0.178%, B:0.0028%, other is Fe and relict element.
According to mass percent, the chemical composition of described boracic duplex stainless steel is, C:0.020%, Si:0.54%, Mn:1.20%, P:0.024%, S:0.0004%, Cr:22.20%, Ni:5.24%, Mo:3.08%, N:0.174%, B:0.0030%, other is Fe and relict element.
Another object of the present invention be to provide technique simple, be easy to operate and control, the boron alloyed smelting process of production cost is low, Boron contents is stable a kind of boracic duplex stainless steel.
For achieving the above object, the technical scheme that the present invention takes is:
The boron alloyed smelting process of described boracic duplex stainless steel, comprises the following steps:
Step one, AOD refining: at 1500 ~ 1540 DEG C, according to mass percent, by chemical composition be: C:1.70 ~ 2.20%, Si:0.10 ~ 0.26%, Mn:0.25 ~ 0.35%, P≤0.024%, S≤0.03%, Cr:17.80 ~ 18.20%, Ni:5.00 ~ 5.40%, B:0.0004 ~ 0.0006%, other molten iron for Fe and relict element is injected in AOD furnace, carries out decarburization, reduction, desulphurization reaction;
Step 2, skims after AOD tapping: pour baked ladle at 1650 DEG C ~ 1700 DEG C from AOD furnace by molten steel, ladle baking to 700 ~ 900 DEG C; Ladle is transported to station of skimming, carries out taking off Slag treatment, staying quantity of slag slag thick is 150 ~ 200mm;
Step 3, LF refining: ladle is transported to LF stove and carry out refining, inlet temperature is 1580 DEG C ~ 1600 DEG C; Carry out Argon operation after entering the station, argon flow amount controls at 300 ~ 500NL/min;
1. feed total oxygen content≤0.002% in aluminum steel adjustment molten steel, aluminum steel feed quantity is 1.0 ~ 1.5 meters/t molten steel;
2. slag material is added: aluminum shot, lime and fluorite, add borax simultaneously; Aluminum shot add-on is 0.2 ~ 0.3kg/t molten steel, and lime adding amount is 5.0 ~ 7.0kg/t molten steel, and fluorite add-on is 3.0 ~ 5.0kg/t molten steel, and borax add-on is 0.694kg ~ 0.844kg/t molten steel;
3. adopt the energization slag of Graphite Electrodes, after slag charge melts completely, use strong bottom blowing stirring 10 ~ 20 minutes, argon flow amount controls at 700 ~ 800NL/min; Under the effect that argon gas stirs, boron enters into molten steel by diffusion from slag, exists with the form of acid-soluble boron;
4. thermometric sampling, according to result of laboratory test, by adding molybdenum-iron, ferrosilicon, silicomanganese, ferrochrome and metallic nickel, Mo, Si, Mn, Cr, Ni composition in adjustment molten steel, adjustment liquid steel temperature is to 1520 ~ 1525 DEG C;
5. feed silicon-calcium wire and carry out Control and Inclusion Removal, silicon-calcium wire feed quantity is 7.0 ~ 8.0 meters/t molten steel; Adjustment argon flow amount, weakly blow 12 ~ 20 minutes, argon bottom-blowing flow is 100 ~ 200 NL/min; The chemical composition obtaining molten steel is, C:0.018 ~ 0.025%, Si:0.48 ~ 0.54%, Mn:1.15 ~ 1.20%, P≤0.025%, S≤0.0005%, Cr:22.20 ~ 22.30%, Ni:5.20 ~ 5.25%, Mo:3.08 ~ 3.12%, N:0.174 ~ 0.184%, B:0.0028 ~ 0.0035%, other is Fe and relict element;
Step 4, continuous casting: molten steel is transported to continuous casting platform and casts, obtains described boracic two-phase stainless product made from steel.
Adopt boracic duplex stainless steel provided by the invention and smelting process thereof, the borax of interpolation is for containing acidic oxide B 2o 3slag former, borax wide material sources, aboundresources, low price; Production technique is simple and easy, and borax, except as the modification agent of slag, can also complete the alloying of boron, can ensure stably to obtain appropriate acid-soluble boron, significantly can reduce fusing point and the viscosity of slag in the smelting of boracic duplex stainless steel.This smelting process, adds borax under the prerequisite reducing entire oxygen content in the steel content, ensures the acid-soluble boron that stable acquisition is appropriate.
Accompanying drawing explanation
Fig. 1 is process flow sheet of the present invention.
Fig. 2 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate that the embodiment of the present invention 1 is produced.
Fig. 3 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate adopting boron line to produce with embodiment 1 the same terms.
Fig. 4 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate that the embodiment of the present invention 2 is produced.
Fig. 5 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate adopting boron line to produce with embodiment 2 the same terms.
Fig. 6 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate that the embodiment of the present invention 3 is produced.
Fig. 7 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate adopting boron line to produce with embodiment 3 the same terms.
Embodiment
Below in conjunction with specific embodiment and accompanying drawing thereof, the present invention is described in further detail, but embodiments of the present invention are not limited thereto.
A kind of boracic duplex stainless steel provided by the invention, according to mass percent, chemical composition is, C:0.018 ~ 0.025%, Si:0.48 ~ 0.54%, Mn:1.15 ~ 1.20%, P≤0.025%, S≤0.0005%, Cr:22.20 ~ 22.30%, Ni:5.20 ~ 5.25%, Mo:3.08 ~ 3.12%, N:0.174 ~ 0.184%, B:0.0028 ~ 0.0035%, other is Fe and relict element.
As shown in Figure 1, be the production scheme of this boracic duplex stainless steel.
Embodiment 1
Steel grade 2205 duplex stainless steel, according to mass percent, its chemical composition is, C:0.018%, Si:0.48%, Mn:1.18%, P:0.025%, S:0.0003%, Cr:22.27%, Ni:5.25%, Mo:3.10%, N:0.184%, B:0.0035%, other is Fe and relict element.
The boron alloyed smelting process of this boracic duplex stainless steel, comprises the following steps:
1.AOD refining: at 1530 DEG C, according to mass percent, by chemical composition be: C:1.70%, Si:0.15%, Mn:0.25%, P:0.024%, S:0.03%, Cr:17.95%, Ni:5.40%, B:0.0005%, other is that the molten iron 92.4 tons of Fe and relict element is injected in AOD furnace, carries out decarburization, reduction, desulphurization reaction.
1. decarburization: top and bottom complex blowing oxygen carries out decarburization, for adding fast response, bottom blowing nitrogen stirs.The lime of 70kg/t molten steel and the high carbon ferro-chrome of 110.2kg/t molten steel is added in carbon rejection process.Add lime 70 × 106.6=7462kg altogether, high carbon ferro-chrome 110.2 × 106.6=11750kg.
When carbon content is less than 0.01%, carry out reducing, the operation of desulfurization.
2. reduce: in AOD furnace, add the ferro-silicon of 16.0kg/t molten steel, the silicomanganese of 16.0kg/t molten steel and the aluminium block of 6.5kg/t molten steel, Cr oxidized in reduced blast furnace 2o 3.At utmost deslagging after this stage terminates.
Add ferro-silicon 16 × 106.6=1705.6kg altogether, silicomanganese 16 × 106.6=1705.6kg, aluminium block 6.5 × 106.6=692.9kg.
Ferrosilicon composition range is, Si:72 ~ 80%, S≤0.030%, P≤0.040%.Silicomanganese composition range is, Si:20 ~ 25%, Mn:60 ~ 65%, P≤0.040%, S≤0.030%.The composition of aluminium block is: 99.5%Al, 0.4%Fe.
3. desulfurization: the lime adding 10.0kg/t molten steel, makes the basicity of slag in AOD converter be 2.3, makes AOD tapping sulphur content be less than 0.001%; Add lime 10 × 106.6=1066Kg altogether.
Skim after 2.AOD tapping: 106.6t molten steel is poured in baked ladle at 1650 DEG C from AOD furnace, ladle baking to 800 DEG C; Ladle is transported to station of skimming, carries out taking off Slag treatment, staying quantity of slag slag thick is 200mm;
3. LF refining: ladle is transported to LF stove and carry out refining, inlet temperature is 1580 DEG C.Carry out Argon operation after entering the station, argon flow amount controls at 500NL/min.
1. feed total oxygen content to 0.0020% in aluminum steel adjustment molten steel, aluminum steel feed quantity is 1.0 meters/t molten steel; 1.0 × 106.6=106.6 rice; Aluminum steel weight is 0.3kg/ rice, and chemical composition is: 98%Al, 0.4%Fe.
2. add slag material: aluminum shot, lime and fluorite, add borax simultaneously, borax is as steel slag modification agent.
Aluminum shot chemical composition is: 98%Al, 0.4%Fe.
Calcification studies and is divided into: CaO >=88.0%, P≤0.01%, S≤0.045%, and C is solid≤and 0.7%, SiO2≤3.0%, activity degree >=350ml, raw burning≤7.0%, granularity: 10 ~ 100mm >=90%.
The chemical composition of fluorite is: CaF 2>=75.0%, SiO 2>=9.0%, P≤0.01%, S≤0.045%, C gu≤ 0.3%, granularity: 10 ~ 100mm>=90%.
Borax (Na 2b 40 710H 2o) as the boron alloyed raw material of molten steel, chemical constitution is the sodium tetraborate containing 10 water moleculess, 320 DEG C lose whole crystal water, proportion 1.73, containing acidic oxide B in melt 2o 3.The borax added is for containing acidic oxide B 2o 3slag former, significantly can reduce fusing point and the viscosity of slag, be conducive to the floating of inclusion.
Aluminum shot add-on is 0.3kg/t molten steel, and lime adding amount is 7.0kg/t molten steel, and fluorite add-on is 4.0kg/t molten steel, and borax add-on is 0.844kg/t molten steel.
Add aluminum shot 0.3 × 106.6=31.98kg altogether, lime 7.0 × 106.6=746.2kg, fluorite 4.0 × 106.6=426.4kg, borax 0.844 × 106.6=90kg.
3. adopt the energization slag of Graphite Electrodes, after slag charge melts completely, use strong bottom blowing stirring 20 minutes, argon flow amount controls at 800NL/min.Under the effect that argon gas stirs, boron enters into molten steel by diffusion from slag, exists with the form of acid-soluble boron.
4. thermometric sampling, according to result of laboratory test, by adding molybdenum-iron, ferrosilicon, silicomanganese, ferrochrome and metallic nickel, Mo, Si, Mn, Cr, Ni composition in adjustment molten steel, adjustment liquid steel temperature is to 1525 DEG C.
5. feed silicon-calcium wire and carry out Control and Inclusion Removal, silicon-calcium wire feed quantity is 8.0 meters/t molten steel; Silicon-calcium wire weight is 0.25kg/ rice, and chemical composition is, Si:55 ~ 60%, Ca >=28%, P≤0.04%, S≤0.04%; Feeding 8.0 × 106.6=852.8 rice silicon-calcium wire altogether.
Adjustment argon flow amount, weakly blow 20 minutes, argon bottom-blowing flow is 100NL/min; Obtain the satisfactory molten steel of chemical composition.
Get molten steel sample preparation, adopt direct reading spectrometry detection method, according to mass percent, detect that the chemical composition of sample is: C:0.018%, Si:0.48%, Mn:1.18%, P:0.025%, S:0.0003%, Cr:22.27%, Ni:5.25%, Mo:3.10%, N:0.184%, B:0.0035%, other is Fe and relict element.
4. continuous casting: molten steel is transported to continuous casting platform and casts, obtains boracic two-phase stainless product made from steel.
As can be seen from the detection data of direct-reading spectrometer, in product, boron meets target boron content requirement, illustrates that employing borax can reach boron level in the product adopting ferro-boron or boron line to produce.
Fig. 2 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate that the embodiment of the present invention 1 is produced.
Fig. 3 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate adopting boron line to produce with embodiment 1 the same terms.
Comparison diagram 2 and Fig. 3, can find out: in the stainless steel NO.1 sheet metal phase constitution produced with borax and boron line, there is not crackle.
Embodiment 2
Steel grade 2205 duplex stainless steel, according to mass percent, its chemical composition is, C:0.025%, Si:0.50%, Mn:1.15%, P:0.022%, S:0.0005%, Cr:22.30%, Ni:5.20%, Mo:3.12%, N:0.178%, B:0.0028%, other is Fe and relict element.
The boron alloyed smelting process of boracic duplex stainless steel, comprises the following steps:
1. AOD refining: at 1540 DEG C, according to mass percent, by chemical composition be: C:2.20%, Si:0.26%, Mn:0.35%, P:0.018%, S:0.013%, Cr:17.80%, Ni:5.00%, B:0.0004%, other is that 93.5 tons of molten iron of Fe and relict element are injected in AOD furnace, carries out decarburization, reduction, desulphurization reaction.
1. decarburization: top and bottom complex blowing oxygen carries out decarburization, for adding fast response, bottom blowing nitrogen stirs.The lime of 70kg/t molten steel and the high carbon ferro-chrome of 116.6kg/t molten steel is added in carbon rejection process.Add lime 75 × 108.0=8100Kg altogether, high carbon ferro-chrome 116.6 × 108.0=11592.8kg.
When carbon content is less than 0.01%, carry out reducing, the operation of desulfurization.
2. reduce: in AOD furnace, add the ferro-silicon of 13.1kg/t molten steel, the silicomanganese of 14.3kg/t molten steel and the aluminium block of 7.1kg/t molten steel, Cr oxidized in reduced blast furnace 2o 3.At utmost deslagging after this stage terminates.
Add ferro-silicon 13.1 × 108.0=1414.8kg altogether, silicomanganese 14.3 × 108.0=1544.4kg, aluminium block 7.1 × 108.0=766.8kg.
Ferrosilicon composition range is, Si:72 ~ 80%, S≤0.030%, P≤0.040%.Silicomanganese composition range is, Si:20 ~ 25%, Mn:60 ~ 65%, P≤0.040% S≤0.030%.The composition of aluminium block is: 99.5%Al, 0.4%Fe.
3. desulfurization: the lime adding 10.5kg/t molten steel, makes the basicity of slag in AOD converter be 2.3, makes AOD tapping sulphur content be less than 0.001%; Add lime 10.5 × 108.0=1134kg altogether.
Skim after 2.AOD tapping: 108.0t molten steel is poured in baked ladle at 1700 DEG C from AOD furnace, ladle baking to 700 DEG C; Ladle is transported to station of skimming, carries out taking off Slag treatment, staying quantity of slag slag thick is 150mm.
3. LF refining: ladle is transported to LF stove and carry out refining, inlet temperature is 1600 DEG C; Carry out Argon operation after entering the station, argon flow amount controls at 400NL/min.
1. feed aluminum steel adjustment entire oxygen content in the steel content to 0.0015%, aluminum steel feed quantity is 1.5 meters/t molten steel; 1.5 × 108.0=162.0 rice; Aluminum steel weight is 0.3kg/ rice, and chemical composition is: 98%Al, 0.4%Fe.
2. add slag material: aluminum shot, lime and fluorite, add borax simultaneously, borax is as steel slag modification agent.
Aluminum shot chemical composition is: 98%Al, 0.4%Fe.
Calcification studies and is divided into: CaO >=88.0%, P≤0.01%, S≤0.045%, and C is solid≤and 0.7%, SiO2≤3.0%, activity degree >=350ml, raw burning≤7.0%, granularity: 10 ~ 100mm >=90%.
The chemical composition of fluorite is: CaF 2>=75.0%, SiO 2>=9.0%, P≤0.01%, S≤0.045%, C gu≤ 0.3%, granularity: 10 ~ 100mm>=90%.
Borax (Na 2b 40 710H 2o) as the boron alloyed raw material of molten steel, chemical constitution is the sodium tetraborate containing 10 water moleculess, 320 DEG C lose whole crystal water, proportion 1.73, containing acidic oxide B in melt 2o 3.The borax added is for containing acidic oxide B 2o 3slag former, significantly can reduce fusing point and the viscosity of slag, be conducive to the floating of inclusion.
Aluminum shot add-on is 0.2kg/t molten steel, and lime adding amount is 5.0kg/t molten steel, and fluorite add-on is 5.0kg/t molten steel, and borax add-on is 0.694kg/t molten steel.
Add 0.2 × 108.0=21.6kg aluminum shot altogether, 5.0 × 108.0=540.0kg lime, 5.0 × 108.0=540.0kg fluorite and 0.694 × 108.0=75kg borax.
3. adopt the energization slag of Graphite Electrodes, after slag charge melts completely, use strong bottom blowing stirring 10 minutes, argon flow amount controls at 700NL/min.Under the effect that argon gas stirs, boron enters into molten steel by diffusion from slag, exists with the form of acid-soluble boron.
4. thermometric sampling, according to result of laboratory test, adjusts Mo, Si, Mn, Cr, Ni composition in molten steel by adding molybdenum-iron, ferrosilicon, silicomanganese, ferrochrome and metallic nickel, and adjustment liquid steel temperature is to 1520 DEG C.
5. feed silicon-calcium wire and carry out Control and Inclusion Removal, silicon-calcium wire feed quantity is 7.0 meters/t molten steel; Silicon-calcium wire weight is 0.25kg/ rice, and chemical composition is, Si:55 ~ 60%, Ca >=28%, P≤0.04%, S≤0.04%; Feeding 7.0 × 108.0=756.0 rice silicon-calcium wire altogether.
Adjustment argon flow amount, weakly blow 15 minutes, argon bottom-blowing flow is 150NL/min; Obtain the satisfactory molten steel of chemical composition.
Get molten steel sample preparation, adopt direct reading spectrometry detection method, according to mass percent, detect that the chemical composition of sample is: C:0.025%, Si:0.50%, Mn:1.15%, P:0.022%, S:0.0005%, Cr:22.30%, Ni:5.20%, Mo:3.12%, N:0.178%, B:0.0028%, other is Fe and relict element.
4. continuous casting: molten steel is transported to continuous casting platform and casts, obtains described boracic two-phase stainless product made from steel.
As can be seen from the detection data of direct-reading spectrometer, in product, boron meets target boron content requirement, illustrates that employing borax can reach boron level in the product adopting ferro-boron or boron line to produce.
Fig. 4 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate that the embodiment of the present invention 2 is produced.
Fig. 5 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate adopting boron line to produce with embodiment 2 the same terms.
Comparison diagram 4 and Fig. 5, can find out: in the stainless steel NO.1 sheet metal phase constitution produced with borax and boron line, there is not crackle.
Embodiment 3
Steel grade 2205 duplex stainless steel, according to mass percent, its chemical composition is, C:0.020%, Si:0.54%, Mn:1.20%, P:0.024%, S:0.0004%, Cr:22.20%, Ni:5.24%, Mo:3.08%, N:0.174%, B:0.0030%, other is Fe and relict element.
The boron alloyed smelting process of boracic duplex stainless steel, comprises the following steps:
1. AOD refining: at 1500 DEG C, according to mass percent, by chemical composition be: C:1.93%, Si:0.10%, Mn:0.31%, P:0.021%, S:0.020%, Cr:18.20%, Ni:5.20%, B:0.0006%, other is that the molten iron 92.5 tons of Fe and relict element is injected in AOD furnace, carries out decarburization, reduction, desulphurization reaction.
1. decarburization: top and bottom complex blowing oxygen carries out decarburization, for adding fast response, bottom blowing nitrogen stirs.The lime of 70kg/t molten steel and the high carbon ferro-chrome of 110.8kg/t molten steel is added in carbon rejection process.Add lime 80 × 105.8=8464kg altogether, high carbon ferro-chrome 110.8 × 105.8=11722.6kg.
When carbon content is less than 0.01%, carry out reducing, the operation of desulfurization.
2. reduce: in AOD furnace, add the ferro-silicon of 13.4kg/t molten steel, the silicomanganese of 15.1kg/t molten steel and the aluminium block of 5.7kg/t molten steel, Cr oxidized in reduced blast furnace 2o 3.At utmost deslagging after this stage terminates.
Add ferro-silicon 13.4 × 105.8=1417.7kg altogether, silicomanganese 15.1 × 105.8=1597.6kg, aluminium block 5.7 × 105.8=603.1kg.
Ferrosilicon composition range is, Si:72 ~ 80%, S≤0.030%, P≤0.040%.Silicomanganese composition range is, Si:20 ~ 25%, Mn:60 ~ 65%, P≤0.040%, S≤0.030%.The composition of aluminium block is: 99.5%Al, 0.4%Fe.
3. desulfurization: the lime adding 10.2kg/t molten steel, makes the basicity of slag in AOD converter be 2.3, makes AOD tapping sulphur content be less than 0.001%; Add lime 10.2 × 105.8=1079.2kg altogether.
Skim after 2.AOD tapping: 105.8t molten steel is poured in baked ladle at 1665 DEG C from AOD furnace, ladle baking to 900 DEG C; Ladle is transported to station of skimming, carries out taking off Slag treatment, staying quantity of slag slag thick is 170mm.
3.LF refining: ladle is transported to LF stove and carry out refining, inlet temperature is 1590 DEG C; Carry out Argon operation after entering the station, argon flow amount controls at 450NL/min.
1. feed aluminum steel adjustment entire oxygen content in the steel content to 0.0018%, aluminum steel feed quantity is 1.2 meters/t molten steel; 1.2 × 105.8=126.96 rice; Aluminum steel weight is 0.3kg/ rice, and chemical composition is: 98%Al, 0.4%Fe.
2. add slag material: aluminum shot, lime and fluorite, add borax simultaneously, borax as steel slag modification agent,
Aluminum shot chemical composition is: 98%Al, 0.4%Fe.
Calcification studies and is divided into: CaO >=88.0%, P≤0.01%, S≤0.045%, and C is solid≤and 0.7%, SiO2≤3.0%, activity degree >=350ml, raw burning≤7.0%, granularity: 10 ~ 100mm >=90%.
The chemical composition of fluorite is: CaF 2>=75.0%, SiO 2>=9.0%, P≤0.01%, S≤0.045%, C gu≤ 0.3%, granularity: 10 ~ 100mm>=90%.
Borax (Na 2b 40 710H 2o) as the boron alloyed raw material of molten steel, chemical constitution is the sodium tetraborate containing 10 water moleculess, 320 DEG C lose whole crystal water, proportion 1.73, containing acidic oxide B in melt 2o 3.The borax added is for containing acidic oxide B 2o 3slag former, significantly can reduce fusing point and the viscosity of slag, be conducive to the floating of inclusion.
Aluminum shot add-on is 0.25kg/t molten steel, and lime adding amount is 6.0kg/t molten steel, and fluorite add-on is 3.0kg/t molten steel, and borax add-on is 0.709kg/t molten steel.
Add 0.25 × 105.8=26.45kg aluminum shot altogether, 6.0 × 105.8=634.8kg lime, 3.0 × 105.8=317.4kg fluorite, 0.709 × 105.8=75kg borax.
3. adopt the energization slag of Graphite Electrodes, after slag charge melts completely, use strong bottom blowing stirring 15 minutes, argon flow amount controls at 750NL/min.Under the effect that argon gas stirs, boron enters into molten steel by diffusion from slag, exists with the form of acid-soluble boron.
4. thermometric sampling, according to result of laboratory test, by adding molybdenum-iron, ferrosilicon, silicomanganese, ferrochrome and metallic nickel, Mo, Si, Mn, Cr, Ni composition in adjustment molten steel, adjustment liquid steel temperature is to 1523 DEG C.
5. feed silicon-calcium wire and carry out Control and Inclusion Removal, silicon-calcium wire feed quantity is 7.5 meters/t molten steel; Silicon-calcium wire weight is 0.25kg/ rice, and chemical composition is, Si:55 ~ 60%, Ca >=28%, P≤0.04%, S≤0.04%; Feeding 7.5 × 105.8=793.5 rice silicon-calcium wire altogether.
Adjustment argon flow amount, weakly blow 12 minutes, argon bottom-blowing flow is 200 NL/min; Obtain the satisfactory molten steel of chemical composition.
Get molten steel sample preparation, adopt direct reading spectrometry detection method, according to mass percent, detect that the chemical composition of sample is: C:0.020%, Si:0.54%, Mn:1.20%, P:0.024%, S:0.0004%, Cr:22.20%, Ni:5.24%, Mo:3.08%, N:0.174%, B:0.0030%, other is Fe and relict element.
4. continuous casting: molten steel is transported to continuous casting platform and casts, obtains described boracic two-phase stainless product made from steel.
As can be seen from the detection data of direct-reading spectrometer, in product, boron meets target boron content requirement, illustrates that employing borax can reach boron level in the product adopting ferro-boron or boron line to produce.
Fig. 6 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate that the embodiment of the present invention 3 is produced.
Fig. 7 is the metallographic structure photo of the steel grade 2205 duplex stainless steel NO.1 plate adopting boron line to produce with embodiment 3 the same terms.
Comparison diagram 6 and Fig. 7, can find out: in the stainless steel NO.1 sheet metal phase constitution produced with borax and boron line, there is not crackle.

Claims (4)

1. a boron alloyed smelting process for boracic duplex stainless steel, is characterized in that, comprise the following steps:
Step one, AOD refining: at 1500 ~ 1540 DEG C, according to mass percent, by chemical composition be: C:1.70 ~ 2.20%, Si:0.10 ~ 0.26%, Mn:0.25 ~ 0.35%, P≤0.024%, S≤0.03%, Cr:17.80 ~ 18.20%, Ni:5. 00 ~ 5.40%, B:0.0004 ~ 0.0006%, other molten iron for Fe and relict element is injected in AOD furnace, carries out decarburization, reduction, desulphurization reaction;
Step 2, skims after AOD tapping: pour baked ladle at 1650 DEG C ~ 1700 DEG C from AOD furnace by molten steel, ladle baking to 700 ~ 900 DEG C; Ladle is transported to station of skimming, carries out taking off Slag treatment, staying quantity of slag slag thick is 150 ~ 200mm;
Step 3, LF refining: ladle is transported to LF stove and carry out refining, inlet temperature is 1580 DEG C ~ 1600 DEG C; Carry out Argon operation after entering the station, argon flow amount controls at 300 ~ 500NL/min;
1. feed total oxygen content≤0.002% in aluminum steel adjustment molten steel, aluminum steel feed quantity is 1.0 ~ 1.5 meters/t molten steel;
2. slag material is added: aluminum shot, lime and fluorite, add borax simultaneously; Aluminum shot add-on is 0.2 ~ 0.3kg/t molten steel, and lime adding amount is 5.0 ~ 7.0kg/t molten steel, and fluorite add-on is 3.0 ~ 5.0kg/t molten steel, and borax add-on is 0.694kg ~ 0.844 kg/t molten steel;
3. adopt the energization slag of Graphite Electrodes, after slag charge melts completely, use strong bottom blowing stirring 10 ~ 20 minutes, argon flow amount controls at 700 ~ 800NL/min; Under the effect that argon gas stirs, boron enters into molten steel by diffusion from slag, exists with the form of acid-soluble boron;
4. thermometric sampling, according to result of laboratory test, by adding molybdenum-iron, ferrosilicon, silicomanganese, ferrochrome and metallic nickel, Mo, Si, Mn, Cr, Ni composition in adjustment molten steel, adjustment liquid steel temperature is to 1520 ~ 1525 DEG C;
5. feed silicon-calcium wire and carry out Control and Inclusion Removal, silicon-calcium wire feed quantity is 7.0 ~ 8.0 meters/t molten steel; Adjustment argon flow amount, weakly blow 12 ~ 20 minutes, argon bottom-blowing flow is 100 ~ 200 NL/min; The chemical composition obtaining molten steel is, C:0.018 ~ 0.025%, Si:0.48 ~ 0.54%, Mn:1.15 ~ 1.20%, P≤0.025%, S≤0.0005%, Cr:22.20 ~ 22.30%, Ni:5.20 ~ 5.25%, Mo:3.08 ~ 3.12%, N:0.174 ~ 0.184%, B:0.0028 ~ 0.0035%, other is Fe and relict element;
Step 4, continuous casting: molten steel is transported to continuous casting platform and casts, obtains described boracic two-phase stainless product made from steel.
2. the boracic duplex stainless steel prepared of method according to claim 1, is characterized in that,
Step one, AOD refining: at 1530 DEG C, according to mass percent, by chemical composition be: C:1.70%, Si:0.15%, Mn:0.25%, P:0.024%, S:0.03%, Cr:17.95%, Ni:5.40%, B:0.0005%, other molten iron for Fe and relict element is injected in AOD furnace, carries out decarburization, reduction, desulphurization reaction;
Step 2, skims after AOD tapping: pour baked ladle at 1650 DEG C from AOD furnace by molten steel, ladle baking to 800 DEG C; Ladle is transported to station of skimming, carries out taking off Slag treatment, staying quantity of slag slag thick is 200mm;
Step 3, LF refining: ladle is transported to LF stove and carry out refining, inlet temperature is 1580 DEG C; Carry out Argon operation after entering the station, argon flow amount controls at 500NL/min;
1. feed total oxygen content≤0.002% in aluminum steel adjustment molten steel, aluminum steel feed quantity is 1.0 meters/t molten steel;
2. slag material is added: aluminum shot, lime and fluorite, add borax simultaneously; Aluminum shot add-on is 0.3kg/t molten steel, and lime adding amount is 7.0kg/t molten steel, and fluorite add-on is 4.0kg/t molten steel, and borax add-on is 0.844 kg/t molten steel;
3. adopt the energization slag of Graphite Electrodes, after slag charge melts completely, use strong bottom blowing stirring 20 minutes, argon flow amount controls at 800NL/min; Under the effect that argon gas stirs, boron enters into molten steel by diffusion from slag, exists with the form of acid-soluble boron;
4. thermometric sampling, according to result of laboratory test, by adding molybdenum-iron, ferrosilicon, silicomanganese, ferrochrome and metallic nickel, Mo, Si, Mn, Cr, Ni composition in adjustment molten steel, adjustment liquid steel temperature is to 1525 DEG C;
5. feed silicon-calcium wire and carry out Control and Inclusion Removal, silicon-calcium wire feed quantity is 8.0 meters/t molten steel; Adjustment argon flow amount, weakly blow 20 minutes, argon bottom-blowing flow is 100NL/min; The chemical composition obtaining molten steel is, C:0.018%, Si:0.48%, Mn:1.18%, P:0.025%, S:0.0003%, Cr:22.27%, Ni:5.25%, Mo:3.10%, N:0.184%, B:0.0035%, and other is Fe and relict element;
Step 4, continuous casting: molten steel is transported to continuous casting platform and casts, obtaining chemical composition is, C:0.018%, Si:0.48%, Mn:1.18%, P:0.025%, S:0.0003%, Cr:22.27%, Ni:5.25%, Mo:3.10%, N:0.184%, B:0.0035%, other is the boracic two-phase stainless product made from steel of Fe and relict element.
3. the boracic duplex stainless steel prepared of method according to claim 1, is characterized in that,
Step one, AOD refining: at 1540 DEG C, according to mass percent, by chemical composition be: C:2.20%, Si:0.26%, Mn:0.35%, P:0.018%, S:0.013%, Cr:17.80%, Ni:5.00%, B:0.0004%, other molten iron for Fe and relict element is injected in AOD furnace, carries out decarburization, reduction, desulphurization reaction;
Step 2, skims after AOD tapping: pour baked ladle at 1700 DEG C from AOD furnace by molten steel, ladle baking to 700 DEG C; Ladle is transported to station of skimming, carries out taking off Slag treatment, staying quantity of slag slag thick is 150mm;
Step 3, LF refining: ladle is transported to LF stove and carry out refining, inlet temperature is 1600 DEG C; Carry out Argon operation after entering the station, argon flow amount controls at 400NL/min;
1. feed total oxygen content≤0.002% in aluminum steel adjustment molten steel, aluminum steel feed quantity is 1.5 meters/t molten steel;
2. slag material is added: aluminum shot, lime and fluorite, add borax simultaneously; Aluminum shot add-on is 0.2kg/t molten steel, and lime adding amount is 5.0kg/t molten steel, and fluorite add-on is 5.0kg/t molten steel, and borax add-on is 0.694 kg/t molten steel;
3. adopt the energization slag of Graphite Electrodes, after slag charge melts completely, use strong bottom blowing stirring 10 minutes, argon flow amount controls at 700NL/min; Under the effect that argon gas stirs, boron enters into molten steel by diffusion from slag, exists with the form of acid-soluble boron;
4. thermometric sampling, according to result of laboratory test, by adding molybdenum-iron, ferrosilicon, silicomanganese, ferrochrome and metallic nickel, Mo, Si, Mn, Cr, Ni composition in adjustment molten steel, adjustment liquid steel temperature is to 1520 DEG C;
5. feed silicon-calcium wire and carry out Control and Inclusion Removal, silicon-calcium wire feed quantity is 7.0 meters/t molten steel; Adjustment argon flow amount, weakly blow 15 minutes, argon bottom-blowing flow is 150NL/min; The chemical composition obtaining molten steel is, C:0.025%, Si:0.50%, Mn:1.15%, P:0.022%, S:0.0005%, Cr:22.30%, Ni:5.20%, Mo:3.12%, N:0.178%, B:0.0028%, and other is Fe and relict element;
Step 4, continuous casting: molten steel is transported to continuous casting platform and casts, obtaining chemical composition is, C:0.025%, Si:0.50%, Mn:1.15%, P:0.022%, S:0.0005%, Cr:22.30%, Ni:5.20%, Mo:3.12%, N:0.178%, B:0.0028%, other is the boracic two-phase stainless product made from steel of Fe and relict element.
4. the boracic duplex stainless steel prepared of method according to claim 1, is characterized in that,
Step one, AOD refining: at 1500 DEG C, according to mass percent, by chemical composition be: C:1.93%, Si:0.10%, Mn:0.31%, P:0.021%, S:0.020%, Cr:18.20%, Ni:5.20%, B:0.0006%, other molten iron for Fe and relict element is injected in AOD furnace, carries out decarburization, reduction, desulphurization reaction;
Step 2, skims after AOD tapping: pour baked ladle at 1665 DEG C from AOD furnace by molten steel, ladle baking to 900 DEG C; Ladle is transported to station of skimming, carries out taking off Slag treatment, staying quantity of slag slag thick is 170mm;
Step 3, LF refining: ladle is transported to LF stove and carry out refining, inlet temperature is 1590 DEG C; Carry out Argon operation after entering the station, argon flow amount controls at 450NL/min;
1. feed total oxygen content≤0.002% in aluminum steel adjustment molten steel, aluminum steel feed quantity is 1.2 meters/t molten steel;
2. slag material is added: aluminum shot, lime and fluorite, add borax simultaneously; Aluminum shot add-on is 0.25kg/t molten steel, and lime adding amount is 6.0kg/t molten steel, and fluorite add-on is 3.0kg/t molten steel, and borax add-on is 0.709 kg/t molten steel;
3. adopt the energization slag of Graphite Electrodes, after slag charge melts completely, use strong bottom blowing stirring 15 minutes, argon flow amount controls at 750NL/min; Under the effect that argon gas stirs, boron enters into molten steel by diffusion from slag, exists with the form of acid-soluble boron;
4. thermometric sampling, according to result of laboratory test, by adding molybdenum-iron, ferrosilicon, silicomanganese, ferrochrome and metallic nickel, Mo, Si, Mn, Cr, Ni composition in adjustment molten steel, adjustment liquid steel temperature is to 1523 DEG C;
5. feed silicon-calcium wire and carry out Control and Inclusion Removal, silicon-calcium wire feed quantity is 7.5 meters/t molten steel; Adjustment argon flow amount, weakly blow 12 minutes, argon bottom-blowing flow is 200NL/min; The chemical composition obtaining molten steel is, C:0.020%, Si:0.54%, Mn:1.20%, P:0.024%, S:0.0004%, Cr:22.20%, Ni:5.24%, Mo:3.08%, N:0.174%, B:0.0030%, and other is Fe and relict element;
Step 4, continuous casting: molten steel is transported to continuous casting platform and casts, obtaining chemical composition is, C:0.020%, Si:0.54%, Mn:1.20%, P:0.024%, S:0.0004%, Cr:22.20%, Ni:5.24%, Mo:3.08%, N:0.174%, B:0.0030%, other is the boracic two-phase stainless product made from steel of Fe and relict element.
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