CN102021488B - Steel for nuclear-island seamless steel tube and production method thereof - Google Patents

Steel for nuclear-island seamless steel tube and production method thereof Download PDF

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CN102021488B
CN102021488B CN 201010565800 CN201010565800A CN102021488B CN 102021488 B CN102021488 B CN 102021488B CN 201010565800 CN201010565800 CN 201010565800 CN 201010565800 A CN201010565800 A CN 201010565800A CN 102021488 B CN102021488 B CN 102021488B
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steel
refining
nuclear
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production
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CN102021488A (en
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胡茂会
杨文明
黄国玖
苏雄杰
贾宁波
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攀钢集团钢铁钒钛股份有限公司
攀钢集团成都钢钒有限公司
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Abstract

The invention belongs to the field of metallurgical technology, especially relating to steel for a nuclear-island seamless steel tube and a production method thereof. The steel in the invention comprises the following chemical components in percentage by weight: more than 0 and no more than 0.20 percent of C, no less than 0.10 and no more than 0.35 percent of Si, no less than 0.80 and no more than 1.60 percent of Mn, more than 0 and no more than 0.020 percent of P, more than 0 and no more than 0.015 percent of S, more than 0 and no more than 0.25 percent of Cr, more than 0 and no more than 0.50 percent of Ni, more than 0 and no more than 0.18 percent of Cu, more than 0 and no more than 0.10 percent of Mo, more than 0 and no more than 0.06 percent of V, no less than 0.020 and no more than 0.050 percent of Al, more than 0 and no more than 0.030 percent of Sn and the balance of Fe. The steel in the invention has the advantages of meeting the condition that the carbon equivalent is no more than 0.48 (Ceq = C + Mn/6 + (Cr + Mo + V)/5 + [(Ni +Cu)+ 15]<=0.48), controlling the contents of the main elements such as carbon and manganese in the steel, stabilizing the tensile property of the steel tube subjected to simulated destressing heat treatment, and simultaneously ensuring the tensile properties of the tube body and a sample subjected to the simulated destressing heat treatment to meet the technical standards. Because a residual element nickel as an alloy element is added, the low-temperature impact toughness of the steel in the invention is improved, and the impact toughness requirements for the steel at the temperatures of 0 DEG C and minus 20 DEG C are met.

Description

Steel for nuclear-island seamless steel tube and production method thereof
Technical field
The invention belongs to metallurgical technology field, particularly steel for nuclear-island seamless steel tube and production method thereof.
Background technology
Development along with China's Nuclear Power Industry, the construction of nuclear power station shows a rising trend, and the nuclear power ferrous materials of China's used in nuclear power station relies on import substantially, develops as early as possible the domestic steel that are fit to construction of nuclear power station requirement, has become the grand strategy step of China's Nuclear Power Industry development.Because nuclear island of nuclear power station weldless steel tube environment for use is abominable, require mechanical properties of tubular goods except satisfying the normal temperature service check, also regulation high-temperature behavior, (0 ℃ ,-20 ℃) low temperature impact properties, performance after the sample Analog heat-treating and tube body performance must satisfy the performance index requirement simultaneously, strictly carry out the lamination defect flaw detection by the RCC-M standard, so nuclear island of nuclear power station requires with weldless steel tube to quality product very high.Nuclear island belongs to core level pipe with weldless steel tube, and material is P280GH, and domestic to possess nuclear island steam system and core subsystem very few with the enterprise of core 2,3 grades of seamless steel tube production abilities.
Domestic Wuhan Heavy Industry Casting and Forge Co Ltd production nuclear island is electric furnace → LF refining → VD vacuum → static ingot explained hereafter with the production technique of P280GH steel.The starting material of selecting are high-quality steel scrap, forging stub bar, the pig iron, its ratio 5:3: 2, but the harmful element in the starting material steel scrap such as As, Sn, Pb, Sb content are higher, are difficult to remove in smelting process.Water the static ingot molten steel easily by in the refractory materials of column jecket and runner brick pollute, form large-scale nonmetal inclusion, and the cooling of steel ingot is cooling by air natural, solidifying of molten steel is to carry out gradually to inside from the steel ingot outside, according to molten steel choosing minute crystallization principle, the inclusion final set of low melting point, thus make non-metallic inclusion in steel be gathered in a large number the middle and upper part of steel ingot, greatly reduce the purity of steel.
In sum, the nuclear island main steam pipe material requires very high to purity of steel and stability, and present domestic material does not reach such standard, therefore can not be widely used in the nuclear island of nuclear power station field.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of steel for nuclear-island seamless steel tube, and its chemical composition is by weight percentage: 0<C≤0.20%, 0.10%≤Si≤0.35%, 0.80%≤Mn≤1.60%, 0<P≤0.020%, 0<S≤0.015%, 0<Cr≤0.25%, 0<Ni≤0.50%, 0<Cu≤0.18%, 0<Mo≤0.10%, 0<V≤0.06%, 0.020%≤A1≤0.050%, 0<Sn≤0.030%, Fe are surplus.
Preferably, the steel for nuclear-island seamless steel tube chemical composition is by weight percentage: 0.13%≤C≤0.18%, 0.15%≤Si≤0.30%, 1.10%≤Mn≤1.30%, 0<P≤0.010%, 0<S≤0.008%, 0.16%≤Cr≤0.24%, 0.12%≤Ni≤0.25%, 0<Cu≤0.10%, 0<Mo≤0.05%, 0<V≤0.04%, 0.025%≤Al≤0.045%, 0<Sn≤0.010%, Fe are surplus.
Steel for nuclear-island seamless steel tube of the present invention is when designing chemical composition, satisfy under the condition of carbon equivalent (Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Ni+Cu)/15)≤0.48, control principal element carbon (C), manganese (Mn) content of steel, the stabilized steel pipe die tensile property after thermal treatment of intending eliminating stress guarantees that body and the simulation heat treatment sample tensile property that eliminates stress satisfies the technological standard requirement simultaneously.Residual element nickel (Ni) is added as alloying element, improved the steel for nuclear-island seamless steel tube low-temperature impact toughness, satisfy its 0 ℃ ,-20 ℃ impelling strength requirements.
Second technical problem to be solved by this invention is to provide the production method of above-mentioned steel for nuclear-island seamless steel tube, comprises the following steps:
Water is just made steel in a, electric arc furnace smelting production
The electric furnace feed stock for blast furnace is steel scrap and molten iron, and the molten iron consumption is 25~35% of steel scrap weight, and the oxygen supply by lance flow is 1500~2100Nm 3/ h, oxygen pressure are 1.2~1.8MPa; Tapping process adds iron alloy ferromanganese 10~13Kg/t steel, reductor aluminium ball 2.5~3.5Kg/t steel; 1630~1660 ℃ of tapping temperatures.
B, the refining of LF refining furnace
Just steel-making water is after refining furnace, and the ladle bottom blowing argon gas is made the foaming white slag with special-purpose refining slag, special-purpose refining slag composition CaO:72~78%, Al 2O 3: 15~20%, CaF 2: 7~10%, S:0~0.05%, 1590~1610 ℃ of tapping temperatures, during tapping, the molten aluminium of acid is 0.055~0.075%.
C, arc round billet continuous casting
The molten steel of refining is delivered to the casting of round billet continuous casting machine, and continuous casting ladle, tundish and crystallizer whole process add protective casing, and ladle and protective casing junction employing argon gas add the gasket protection; Use Mg matter tundish paint.
D, continuously cast bloom surface sand-blasting: its surperficial ferric oxide is removed in the casting billet surface sandblast.
E, electroslag remelting steel ingot
The continuously cast bloom that sprayed sand is made the consumable electrode blank and is carried out esr, the binary slag Al of use 2O 330~40%, CaF 260~70%; Melting current 11200~15500A, voltage 75~84V.
F, remelting ingot slow cool
Cooling 40~the 90min of electroslag melt steel spindle band mould hung in the sandpit Slow cooling 50~90 hours after the steel ingot demoulding.
Further, steel scrap chemical composition C:0.08~0.50%, Si:0.10~0.50%, Mn:0.35~0.70%, P:0.004~0.025%, S:0.003~0.025% in step a electric furnace feed stock for blast furnace, Fe is surplus; Molten iron chemical composition C:4.0~4.5%, Si:0~0.35%, P:0~0.09%, S:0.010~0.040%, Fe are surplus.The molten steel composition that just refining of electric furnace obtains: C:0.05~0.08%, P:0.0010~0.0040%, S:0.010~0.040%, Fe are surplus.
Step a utilizes the electric energy melting waste steel, lime slag making dephosphorization, the decarburization of RCB oxygen gun blowing.Electric furnace steel tapping adopts slag free tapping.
Step b refining process adds ferrosilicon, ferromanganese, ferrochrome, nickel plate, aluminium etc. to carry out alloying, adjusts the molten steel chemical composition according to producing each constituent content of required the finished product; Refining finishes to feed CaSi line 0.4~0.8Kg/t steel, guarantees the quiet blowing argon gas time of 8~10 minutes.In continuous casting casting and esr process, easily the scaling loss of oxidation element aluminum is larger, satisfies 0.020~0.050% requirement for guaranteeing product A l, and during tapping, the molten aluminium of acid is 0.055~0.075%.
Step c continuous casting specification φ 220mm~φ 350mm; Being distributed as one section and accounting for 14~20%, two sections and account for 16~22%, three sections and account for 10~16%, four sections and account for 26~34%, five sections and account for 18~23% of continuous casting secondary cooling water, specific water 0.25~0.55L/Kg prevents that strand from producing internal fissure; Molten steel overheat is controlled at 15~35 ℃, and permanent pulling rate casting obtains the circle continuously cast bloom; Different size round billet continuous casting machine pulling rate is preferably φ 220mm:1.2~1.7m/min, φ 280mm:0.7~1.0m/min, φ 350mm:0.45~0.65m/min.
The Ingot Type of step e esr is φ 350mm~φ 600mm.
The refusion and smelting step added the Al powder one time in every 6~8 minutes, and the consumption of aluminium powder is specially: begin to add the Al powder after burning normally, and in front 35 minutes, each add-on 23~30g/t steel; Melted between 25min later on each add-on 35~50g/t steel in 35 minutes after exchanging second consumable electrode; Second comsumable melt 25min is later on to electroslag ingot remelting end, add-on 50~63g/t steel at every turn.
The chemical composition (weight percent) of the steel that the employing aforesaid method makes is: 0<C≤0.20%, 0.10%≤Si≤0.35%, 0.80%≤Mn≤1.60%, 0<P≤0.020%, 0<S≤0.015%, 0<Cr≤0.25%, 0<Ni≤0.50%, 0<Cu≤0.18%, 0<Mo≤0.10%, 0<V≤0.06%, 0.020%≤Al≤0.050%, 0<Sn≤0.030%, Fe are surplus.
The beneficial effect of the inventive method is:
1, control rationally that the casting machine secondary cooling water distributes and the secondary cooling water specific water, guarantee secondary cooling evenly, prevent that strand from producing internal fissure and surface crack.
2, the casting process ladle adopts whole process to add the protective casing protective casting to tundish, tundish to crystallizer; ladle and protective casing junction employing argon shield; prevent secondary oxidation of steel; adopt Mg matter tundish paint to alleviate the molten steel inclusion content increase that the etch of tundish refractory materials brings, guarantee the purity of molten steel.
When 3, adopting esr, the molten steel drop passes the wash heat process that slag blanket enters the molten bath, further removes the inclusion in molten steel, improves purity of steel; The characteristics of utilizing esr to solidify while melting, the solidified structure of change steel ingot, the density of raising steel ingot makes steel tube performance stable.
Embodiment
The technological process of production of the present invention: electric arc furnace smelting → LF refining → round billet continuous casting → cold bed → check → sandblast → electroslag remelting steel ingot → ingot slow cool.Specifically comprise the following steps:
1, electric arc furnace smelting
The electric arc furnace feed stock for blast furnace is steel scrap and molten iron, steel scrap chemical composition C:0.08~0.50%, Si:0.10~0.50%, Mn:0.35~0.70%, P:0.004~0.025%, S:0.003~0.025%, Fe is surplus, and molten iron chemical composition C:4.0~4.5%, Si:0~0.35%, P:0~0.09%, S:0.01~0.04%, Fe are surplus.The molten iron consumption is 25~35% of steel scrap weight, utilizes the electric energy melting waste steel, lime slag making dephosphorization, oxygen gun blowing decarburization; It is surplus that electric furnace is just made steel water constituent: C:0.05~0.08%, P:0.0010~0.0040%, S:0.010~0.040%, Fe; Tapping process adds iron alloy ferromanganese 10~13Kg/t steel, reductor aluminium ball 2.5~3.5Kg/t steel; Electric furnace steel tapping adopts slag free tapping.
2, LF refining furnace refining
Just steel-making water is after refining furnace, and the ladle bottom blowing argon gas is made the foaminess white slag with special-purpose refining slag, special-purpose refining slag composition CaO:72~78%, Al 2O 3: 15~20%, CaF 2: 7~10%, S:0~0.05%; Refining process adds ferrosilicon, ferromanganese, ferrochrome, nickel plate, aluminium etc. to carry out alloying, adjusts the molten steel chemical composition according to producing each constituent content of required the finished product; Refining finishes to feed CaSi line 0.4~0.8Kg/t steel, guarantee the quiet blowing argon gas time of 8~10 minutes, 1590~1610 ℃ of tapping temperatures, in continuous casting casting and esr process, easily the scaling loss of oxidation element aluminum is larger, for guaranteeing that product A l satisfies 0.020~0.050% requirement, during tapping, the molten aluminium of acid is 0.055~0.075%.
3, arc round billet continuous casting
The molten steel of refining is delivered to the casting of round billet continuous casting machine, and continuous casting ladle, tundish and crystallizer whole process add protective casing, and ladle and protective casing junction employing argon gas add the gasket protection; Use Mg matter tundish paint.
Continuous casting specification φ 220mm~φ 350mm; Being distributed as one section and accounting for 14~20%, two sections and account for 16~22%, three sections and account for 10~16%, four sections and account for 26~34%, five sections and account for 18~23% of continuous casting secondary cooling water, specific water 0.25~0.55L/Kg prevents that strand from producing internal fissure; Molten steel overheat is controlled at 15~35 ℃, and permanent pulling rate casting obtains the circle continuously cast bloom; Different size round billet continuous casting machine pulling rate is preferably φ 220mm:1.2~1.7m/min, φ 280mm:0.7~1.0m/min, φ 350mm:0.45~0.65m/min.
4, continuously cast bloom surface sand-blasting: its surperficial ferric oxide is removed in the casting billet surface sandblast.
5, electroslag remelting steel ingot
The continuously cast bloom that sprayed sand is made the consumable electrode blank and is carried out esr, the binary slag Al that esr uses 2O 330~40%, CaF 260~70%; Melting current 11200~15500A, voltage 75~84V.
The Ingot Type of esr is φ 350mm~φ 600mm, and the refusion and smelting step added the Al powder one time in every 6~8 minutes, and the consumption of aluminium powder is specially: begin to add the Al powder after burning normally, and in front 35 minutes, each add-on 23~30g/t steel; Melted between 25min later on each add-on 35~50g/t steel in 35 minutes after exchanging second consumable electrode; Second comsumable melt 25min is later on to electroslag ingot remelting end, add-on 50~63g/t steel at every turn.
6, remelting ingot slow cool
Cooling 40~the 90min of electroslag melt steel spindle band mould hung in the sandpit Slow cooling 50~90 hours after the steel ingot demoulding.
Because nuclear island core level pipe is strict to purity of steel, therefore refining furnace need be controlled deoxidation of molten steel, desulfurization, alloying and slagging process well: the water of just making steel is strengthened deoxidation fast, adopt special-purpose refining slag to make fast white slag, the white slag hold-time was greater than 20 minutes, make fast white slag and guarantee that the not oxidized and refining white slag of alloying element to the absorption of foreign substance in molten steel, improves Molten Steel Cleanliness; The Argon process avoids molten steel to turn over greatly, effectively deviates from gas and inclusion in steel; Feed CaSi line 0.40~0.80Kg/t steel after refining finishes, inclusion is carried out deformation process, improve fluidity molten steel; After refining finishes, guarantee the quiet blowing argon gas time of 8~10 minutes, make in steel chemical composition and temperature even, inclusion is further removed.
The arc round billet continuous casting needs rationally to control the casting machine secondary cooling water and distributes and the secondary cooling water specific water, guarantees that secondary is cooling evenly; The continuous casting ladle adopts whole process to add the protective casing protective casting to tundish, tundish to crystallizer, and ladle and protective casing junction employing argon shield, prevent secondary oxidation of steel simultaneously, guarantees purity of steel; Use Mg matter tundish paint, alleviate the molten steel inclusion content increase that the etch of tundish refractory materials brings.
The invention will be further elaborated below in conjunction with embodiment.Embodiment only is used for explanation the present invention, rather than limits by any way the present invention.
Embodiment 1
One, electrosmelting is just made steel water
Electric furnace enters 56 tons of stove high-quality steel scraps, 30 tons of molten iron, molten iron main chemical compositions C:4.0%, Si:0.35%, P:0.09%, S:0.010%, Fe are surplus, and high-quality steel scrap main chemical compositions C:0.50%, Si:0.50%, Mn:0.70%, P:0.025%, S:0.003%, Fe are surplus.Lime slag making dephosphorization, lime consumption 51kg/t steel is used the oxygen gun blowing decarburization, oxygen depletion 41Nm 3/ t steel.Tapping process adds iron alloy ferromanganese 13Kg/t steel, reductor aluminium ball 3.5Kg/t steel; Electric furnace adopts slag free tapping.It is surplus that electric furnace is just made steel water constituent C:0.08%, P:0.004%, S:0.024%, Fe.
Two, LF refining furnace refining
The first steel-making water of electrosmelting carries out refining at the LF refining furnace, and the refining slag composition that uses is CaO:77%, Al 2O 3: 15%, CaF 2: 7%, S:0.05%, surplus is ash; Refining process adds low carbon ferrochromium 150Kg, nickel plate 80Kg, aluminium 80Kg, low manganese 300Kg to carry out alloying, adjusts alloy element component; Feed CaSi line 0.4Kg/t steel after refining finishes, inclusion content in melting steel is carried out denaturing treatment; 1610 ℃ of refining furnace tapping temperatures; The sour molten aluminium of tapping is 0.075%.After refining finishes, the quiet blowing argon gas of power failure is 8 minutes, has blown the argon gas tapping, hangs continuous casting working procedure and justifies the base casting.
Three, arc round billet continuous casting
Continuous casting casting specification φ 350mm, being distributed as a section and accounting for 15%, two section and account for 22%, three section and account for 16%, four section and account for 26%, five section and account for 21%, specific water 0.25L/Kg of continuous caster secondary cooling water; The continuous casting ladle adopts whole process to add the protective casing protective casting to tundish, tundish to crystallizer, and ladle and protective casing junction employing argon gas add the gasket protection simultaneously; Tundish paint is Mg matter, 35 ℃ of molten steel overheats, pulling rate 0.45m/min.
After strand cutting, cooling on turn over cooling bed, deliver to the sandblast station after slab cooling.
Four, sandblast
Sandblasting is carried out on the continuously cast bloom surface, removes oxidized iron sheets on surface of casting blank, and the strand power transmission slag hearth after sandblast carries out esr.
Five, electroslag remelting steel ingot
Adopt the continuously cast bloom of φ 350mm to make consumable electrode remelting φ 600mm, the round ingot of 5.5 tons, slag system is by Al 2O 3, CaF 2Form, its proportioning is: Al 2O 335%, CaF 265%, consumption 28kg/t props up steel; The refusion and smelting power supply system is: voltage 84V, electric current 15500A.Al powder add-on: begin to add the Al powder after burning normally, added once in front 35 minutes every 7 minutes, each add-on 30g/t steel; Melted between 25 minutes after exchanging second electrode later in 35 minutes, and added once each add-on 50g/t steel in every 7 minutes; Second electrode melting finished to esr after 25 minutes, added once each add-on 63g/t steel in every 7 minutes.
Six, ingot slow cool
The cooling 90min of electroslag melt steel spindle band mould hangs in the sandpit Slow cooling and namely got product in 90 hours after the steel ingot demoulding.
The P280GH steel finished product that makes contains C:0.13%, Si:0.30%, Mn:1.30%, P:0.008%, S:0.003%, Cr:0.16%, Ni:0.25%, Cu:0.08%, Mo:0.02%, V:0.01%, Al:0.029%, Sn0.006%, Fe are surplus.
Electroslag ingot consolidated structure that esr makes is fine and close, and purity of steel is high, and surface quality is good, and the specification of quality of nuclear island core level tube material is satisfied in stable performance.
Table 1 product nonmetal inclusion grading/level
Classification Category-A Category-B The C class The D class The Ds class
The product grading 0.5 0.5 0.5 0.5 0.5
The technical standard requirement ≤ 2.0 ≤ 2.0 ≤ 2.0 ≤ 2.0 ≤ 2.0
Table 2 product normal tensile property, low temperature impact properties
Normal tensile property, low temperature impact properties after the thermal treatment of table 3 product simulation
Can find out that from table 1~table 3 the product purity of steel that makes is high, after normal tensile property, low temperature impact properties and product simulation thermal treatment, normal tensile property, low temperature impact properties index are stablized, and satisfy the specification of quality of nuclear island core level tube material.
Embodiment 2
One, electrosmelting is just made steel water
Electric furnace enters 64 tons of stove high-quality steel scraps, 22 tons of molten iron, molten iron main chemical compositions C:4.5%, Si:0.10%, P:0.020%, S:0.040%, Fe are surplus, and high-quality steel scrap main chemical compositions C:0.20%, Si:0.25%, P:0.020%, S:0.018%, Fe are surplus.Lime slag making dephosphorization, lime consumption 42kg/t steel is used the oxygen gun blowing decarburization, oxygen depletion 44Nm 3/ t steel.Tapping process adds iron alloy ferromanganese 10Kg/t steel, reductor aluminium ball 3.5Kg/t steel; Electric furnace adopts slag free tapping.It is surplus that electric furnace is just made steel water constituent C:0.05%, P:0.0010%, S:0.024%, Fe.
Two, LF refining furnace refining
The first steel-making water of electrosmelting carries out refining at the LF refining furnace, and the refining slag composition that uses is CaO:72%, Al 2O 3: 15%, CaF 2: 10%, S:0.01%, surplus is ash; Refining process adds low carbon ferrochromium 165Kg, nickel plate 91Kg, aluminium 75Kg, low manganese 510Kg to carry out alloying, adjusts alloy element component; Feed CaSi line 0.8Kg/t steel after refining finishes, inclusion content in melting steel is carried out denaturing treatment; 1590 ℃ of refining furnace tapping temperatures; The sour molten aluminium of tapping is 0.055%.After refining finishes, the quiet blowing argon gas of power failure is 10 minutes, has blown the argon gas tapping, hangs continuous casting working procedure and justifies the base casting.
Three, arc round billet continuous casting
Continuous casting casting specification φ 220mm, being distributed as a section and accounting for 20%, two section and account for 16%, three section and account for 12%, four section and account for 34%, five section and account for 18%, specific water 0.55L/Kg of continuous caster secondary cooling water; The continuous casting ladle adopts whole process to add the protective casing protective casting to tundish, tundish to crystallizer, and ladle and protective casing junction employing argon gas add the gasket protection simultaneously; Tundish paint is Mg matter, 15 ℃ of molten steel overheats, pulling rate 1.70m/min.
After strand cutting, cooling on turn over cooling bed, deliver to the sandblast station after slab cooling.
Four, sandblast
Sandblasting is carried out on the continuously cast bloom surface, removes oxidized iron sheets on surface of casting blank, and the strand power transmission slag hearth after sandblast carries out esr.
Five, electroslag remelting steel ingot
Adopt the continuously cast bloom of φ 220mm to make consumable electrode remelting φ 350mm, the round ingot of 1.80 tons, slag system is by Al 2O 3, CaF 2Form, its proportioning is: Al 2O 335%, CaF 265%, consumption 25kg/t steel.The refusion and smelting power supply system is: voltage 75V, electric current 11200A.Al powder add-on: begin to add the Al powder after burning normally, added once in every 7 minutes in front 35min, each add-on 23g/t steel; To the esr end, added once each add-on 35g/t steel after 35min in every 7 minutes.
Six, ingot slow cool
The cooling 40min of electroslag melt steel spindle band mould hangs in the sandpit Slow cooling and namely got product in 50 hours after the steel ingot demoulding.
The P280GH steel finished product that makes contains C:0.18%, Si:0.15%, and Mn:1.10%, P:0.005%, S:0.002%, Cr:0.24%, Ni:0.12%, Cu:0.10%, Mo:0.01%, V:0.02%, Al:0.028%, Fe are surplus.
Electroslag ingot consolidated structure that esr makes is fine and close, and purity of steel is high, and surface quality is good, and the specification of quality of nuclear island core level tube material is satisfied in stable performance.
Table 4 product nonmetal inclusion grading/level
Classification Category-A Category-B The C class The D class The Ds class
The product grading 0.5 0.5 0.5 0.5 0.5
The technical standard requirement ≤ 2.0 ≤ 2.0 ≤ 2.0 ≤ 2.0 ≤ 2.0
Table 5 product normal tensile property, low temperature impact properties
Normal tensile property, low temperature impact properties after the thermal treatment of table 6 product simulation
Can find out that from table 4~table 6 the product purity of steel that makes is high, after normal tensile property, low temperature impact properties and product simulation thermal treatment, normal tensile property, low temperature impact properties index are stablized, and satisfy the specification of quality of nuclear island core level tube material.
Embodiment 3
One, electrosmelting is just made steel water
Electric furnace enters 60 tons of stove high-quality steel scraps, 26 tons of molten iron, molten iron main chemical compositions C:4.2%, Si:0.20%, P:0.045%, S:0.020%, Fe are surplus, and high-quality steel scrap main chemical compositions C:0.35%, Si:0.28%, P:0.015%, S:0.010%, Fe are surplus.Lime slag making dephosphorization, lime consumption 46kg/t steel is used the oxygen gun blowing decarburization, oxygen depletion 43Nm 3/ t steel.Tapping process adds iron alloy ferromanganese 12Kg/t steel, reductor aluminium ball 3.0Kg/t steel; Electric furnace adopts slag free tapping.It is surplus that electric furnace is just made steel water constituent C:0.06%, P:0.003%, S:0.024%, Fe.
Two, LF refining furnace refining
The first steel-making water of electrosmelting carries out refining at the LF refining furnace, and the refining slag composition that uses is CaO:74%, Al 2O 3: 14%, CaF 2: 10%, S:0.03%, surplus is ash; Refining process adds low carbon ferrochromium 150Kg, nickel plate 80Kg, aluminium 80Kg, low manganese 370Kg to carry out alloying, adjusts alloy element component; Feed CaSi line 0.6Kg/t steel after refining finishes, inclusion content in melting steel is carried out denaturing treatment; 1600 ℃ of refining furnace tapping temperatures; The sour molten aluminium of tapping is 0.060%.After refining finishes, the quiet blowing argon gas of power failure is 9 minutes, has blown the argon gas tapping, hangs continuous casting working procedure and justifies the base casting.
Three, arc round billet continuous casting
Continuous casting casting specification φ 280mm, being distributed as a section and accounting for 18%, two section and account for 19%, three section and account for 15%, four section and account for 30%, five section and account for 18%, specific water 0.36L/Kg of continuous caster secondary cooling water; The continuous casting ladle adopts whole process to add the protective casing protective casting to tundish, tundish to crystallizer, and ladle and protective casing junction employing argon gas add the gasket protection simultaneously; Tundish paint is Mg matter, 25 ℃ of molten steel overheats, pulling rate 0.80m/min.
After strand cutting, cooling on turn over cooling bed, deliver to the sandblast station after slab cooling.
Four, sandblast
Sandblasting is carried out on the continuously cast bloom surface, removes oxidized iron sheets on surface of casting blank, and the strand power transmission slag hearth after sandblast carries out esr.
Five, electroslag remelting steel ingot
Adopt the continuously cast bloom of φ 280mm to make consumable electrode remelting φ 450mm, the round ingot of 2.1 tons, slag system is by Al 2O 3, CaF 2Form, its proportioning is: Al 2O 335%, CaF 265%, consumption 34kg/t steel; The refusion and smelting power supply system is: voltage 79V, electric current 12800A.Al powder add-on: begin to add the Al powder after burning normally, added once in every 7 minutes in front 35 minutes, each add-on 30g/t steel; Melted between 25 minutes after exchanging second electrode later in 35 minutes, and added once each add-on 42g/t steel in every 7 minutes; Second electrode melting finished to esr after 25 minutes, added once each add-on 50g/t steel in every 7 minutes.
Six, ingot slow cool
The cooling 65min of electroslag melt steel spindle band mould hangs in the sandpit Slow cooling and namely got product in 60 hours after the steel ingot demoulding.
The P280GH steel finished product that makes contains C:0.16%, Si:0.26%, and Mn:1.20%, P:0.007%, S:0.004%, Cr:0.20%, Ni:0.18%, Cu:0.11%, Mo:0.02%, V:0.01%, Al:0.038%, Fe are surplus.
Electroslag ingot consolidated structure that esr makes is fine and close, and purity of steel is high, and surface quality is good, and the specification of quality of nuclear island core level tube material is satisfied in stable performance.
Table 7 product nonmetal inclusion grading/level
Classification Category-A Category-B The C class The D class The Ds class
The product grading 0.5 0.5 0.5 0.5 0.5
The technical standard requirement ≤ 2.0 ≤ 2.0 ≤ 2.0 ≤ 2.0 ≤ 2.0
Table 8 product normal tensile property, low temperature impact properties
Normal tensile property, low temperature impact properties after the thermal treatment of table 9 product simulation
Can find out that from table 7~table 9 the product purity of steel that makes is high, after normal tensile property, low temperature impact properties and product simulation thermal treatment, normal tensile property, low temperature impact properties index are stablized, and satisfy the specification of quality of nuclear island core level tube material.

Claims (7)

1. the production method of steel for nuclear-island seamless steel tube is characterized in that: comprise the following steps:
Water is just made steel in a, electric arc furnace smelting production
The electric furnace feed stock for blast furnace is steel scrap and molten iron, and the molten iron consumption is 25~35% of steel scrap weight, and the oxygen supply by lance flow is 1500~2100Nm 3/ h, oxygen pressure are 1.2~1.8MPa; Tapping process adds iron alloy ferromanganese 10~13Kg/t steel, reductor aluminium ball 2.5~3.5Kg/t steel; 1630~1660 ℃ of tapping temperatures; Steel scrap chemical composition C:0.08~0.50%, Si:0.10~0.50%, Mn:0.35~0.70%, P:0.004~0.025%, S:0.003~0.025% in the electric furnace feed stock for blast furnace, Fe is surplus; Molten iron chemical composition C:4.0~4.5%, Si:0~0.35%, P:0~0.09%, S:0.010~0.040%, Fe are surplus;
B, the refining of LF refining furnace
Just steel-making water is after refining furnace, and the ladle bottom blowing argon gas is made the foaming white slag with special-purpose refining slag, special-purpose refining slag composition CaO:72~78%, Al 2O 3: 15~20%, CaF 2: 7~10%, S:0~0.05%, 1590~1610 ℃ of tapping temperatures, during tapping, the molten aluminium of acid is 0.055~0.075%;
C, arc round billet continuous casting
The molten steel of refining is delivered to the casting of round billet continuous casting machine, and continuous casting ladle, tundish and crystallizer whole process add protective casing, and ladle and protective casing junction employing argon gas add the gasket protection; Use Mg matter tundish paint;
Continuous casting specification φ 220mm~φ 350mm; Being distributed as one section and accounting for 14~20%, two sections and account for 16~22%, three sections and account for 10~16%, four sections and account for 26~34%, five sections and account for 18~23% of continuous casting secondary cooling water, specific water 0.25~0.55L/Kg prevents that strand from producing internal fissure; Molten steel overheat is controlled at 15~35 ℃, and permanent pulling rate casting obtains the circle continuously cast bloom;
D, continuously cast bloom surface sand-blasting
Its surperficial ferric oxide is removed in the casting billet surface sandblast;
E, electroslag remelting steel ingot
The continuously cast bloom that sprayed sand is made the consumable electrode blank and is carried out esr, the binary slag Al of use 2O 330~40%, CaF 260~70%; Melting current 11200~15500A, voltage 75~84V;
F, remelting ingot slow cool
Cooling 40~the 90min of electroslag melt steel spindle band mould hung in the sandpit Slow cooling 50~90 hours after the steel ingot demoulding.
2. the production method of steel for nuclear-island seamless steel tube according to claim 1, is characterized in that: step a lime slag making dephosphorization, the decarburization of RCB oxygen gun blowing.
3. the production method of steel for nuclear-island seamless steel tube according to claim 1, is characterized in that: step a electric furnace steel tapping employing slag free tapping.
4. the production method of steel for nuclear-island seamless steel tube according to claim 1 is characterized in that: step b refining finishes to feed CaSi line 0.4~0.8Kg/t steel, guarantees the quiet blowing argon gas time of 8~10 minutes; During tapping, the molten aluminium of acid is 0.055~0.075%.
5. the production method of steel for nuclear-island seamless steel tube according to claim 1, it is characterized in that: different size round billet continuous casting machine pulling rate is φ 220mm:1.2~1.7m/min, φ 280mm:0.7~1.0m/min or φ 350mm:0.45~0.65m/min.
6. the production method of steel for nuclear-island seamless steel tube according to claim 1, it is characterized in that: the Ingot Type of step e esr is φ 350mm~φ 600mm.
7. the production method of steel for nuclear-island seamless steel tube according to claim 6, it is characterized in that: the refusion and smelting step added one time the Al powder in every 6~8 minutes, the consumption of aluminium powder is specially: begin to add the Al powder after burning normally, and in front 35 minutes, each add-on 23~30g/t steel; Melted between 25min later on each add-on 35~50g/t steel in 35 minutes after exchanging second consumable electrode; Second comsumable melt 25min is later on to electroslag ingot remelting end, add-on 50~63g/t steel at every turn.
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