CN113403524A - Preparation method of flange material for nuclear power - Google Patents

Preparation method of flange material for nuclear power Download PDF

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Publication number
CN113403524A
CN113403524A CN202110678717.1A CN202110678717A CN113403524A CN 113403524 A CN113403524 A CN 113403524A CN 202110678717 A CN202110678717 A CN 202110678717A CN 113403524 A CN113403524 A CN 113403524A
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refining
flange material
nuclear power
steel
equal
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赵中清
张军
涂露寒
尹凤先
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Chengdu Advanced Metal Materials Industry Technology Research Institute Co Ltd
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Chengdu Advanced Metal Materials Industry Technology Research Institute Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/002—Hybrid process, e.g. forging following casting
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Forging (AREA)

Abstract

The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a preparation method of a flange material for nuclear power. The invention aims to provide a method for preparing a nuclear power flange with more stable process and quality and lower cost. The method sequentially comprises the steps of electric furnace smelting, AOD refining, LF refining, VD refining, casting, forging and heat treatment, and then cooling to room temperature to obtain the flange material; the process conditions of the heat treatment are as follows: normalizing at 1030-1080 ℃ for 4-5 h, tempering at 730-780 ℃ for 2-3 h. The flange material prepared by the method has excellent comprehensive mechanical properties, excellent normal temperature performance, excellent lasting and creep properties below 650 ℃, low linear expansion coefficient and good manufacturability. The method has the advantages of stable process and quality, low cost and good benefit, and can be popularized and used in the field.

Description

Preparation method of flange material for nuclear power
Technical Field
The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a preparation method of a flange material for nuclear power.
Background
With the improvement of the design life and the safety requirement of the third-generation nuclear power station, the pressure vessel forging piece shows the trend of large-scale and integration. At present, the demand of domestic nuclear power is vigorous, and the general safety goal of nuclear power plants is to establish and maintain effective defense against radioactive hazardous substances. The sealing performance of the flanges on the respective devices, whether the container directly contains radioactive materials or serves as a containment vessel of the last barrier, is of no significance to the safety of the nuclear power plant. The bolt flange connection is a connection mode which is very commonly used in nuclear equipment and has very wide related surfaces, so the quality requirement on flange materials is very strict. However, the cost of the material for manufacturing the flange is high, the mechanical property and the manufacturability are poor, and the improvement is urgently needed.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the preparation method of the nuclear power flange is more stable in process and quality and lower in cost.
The technical scheme adopted by the invention is as follows: the preparation method of the flange material for nuclear power comprises the steps of electric furnace smelting, AOD refining, LF refining, VD refining, casting, forging and heat treatment in sequence, and then cooling to room temperature to obtain the flange material; the process conditions of the heat treatment are as follows: normalizing at 1030-1080 ℃ for 4-5 h, tempering at 730-780 ℃ for 2-3 h.
Further, the large-size flange material for nuclear power comprises the following chemical components in percentage by mass: 0.08-0.12% of C, 0.30-0.60% of Mn, 0.20-0.50% of Si, 8.0-9.5% of Cr, less than or equal to 0.40% of Ni, 0.85-1.05% of Mo, 0.06-0.10% of Nb0.06, less than or equal to 0.010% of S, less than or equal to 0.020% of P, 0.03-0.07% of N, 0.18-0.25% of V, less than or equal to 0.04% of Al, and the balance of inevitable impurities.
Further, the steelmaking raw materials used in the electric furnace smelting process comprise: chromium stainless steel returns, low-phosphorus ferromolybdenum, ferrochromium, ferrovanadium, ferroniobium and ferroboron;
wherein the chromium stainless steel return material contains 80-85% of Fe and 8-10% of Cr, the low-phosphorus ferromolybdenum contains 73-77% of Mo and 22-26% of Fe, the ferrochromium contains 63-67% of Cr and 28-32% of Fe, the ferrovanadium contains 48-52% of V and 43-47% of Fe, the ferroniobium contains 93-97% of Nb and 3-5% of Fe, and the ferroboron contains 28-32% of B and 63-67% of Fe.
Further, the electric furnace smelting process meets the following conditions: tapping when the temperature of molten steel is 1650-1660 ℃;
further, the AOD refining process satisfies: tapping after the temperature in the furnace reaches 1670-1680 ℃;
further, the LF refining process satisfies at least one of the following conditions:
adding aluminum with the mass of 0.02-0.04% of that of molten steel into the molten steel;
adding refining slag after the slag is melted, wherein the refining slag is 80 refining slag or 40 refining slag; the addition amount of the refining slag is 20-30 Kg/40 ton of molten steel;
adding carbon powder accounting for 0.01-0.02% of the total amount of the molten steel 30-60 min after the molten steel is put into the furnace;
further, the VD refining process is to blow argon into the steel slag obtained after LF refining; the argon blowing condition satisfies at least one of the following conditions:
the ultimate vacuum degree in the furnace is 65-67 Pa;
the argon blowing flow is 120-160L/min;
the retention time is 18-25 min.
Further, the casting is started when the temperature of the steel slag obtained by VD refining is 1560 +/-5 ℃. The casting conditions satisfy at least one of the following:
pouring the ingot body for 12-15 min;
feeding time of the cap opening is 8-11 min;
the mold shaking time exceeded 12 h.
Further, the forging process comprises twice upsetting and twice drawing, wherein the drawing adopts an FM method, and the forging specification is phi 500-700 mm.
Further, the specific flow of the forging process is as follows:
a. the first upsetting is carried out until the height H of the steel ingot is less than or equal to 1/2H0(H0The original height of the steel ingot); the rolling reduction is more than or equal to 80mm during the first drawing;
b. upsetting for the second time until the height H of the steel ingot is less than or equal to 1/2H0(H0The original height of the steel ingot); the rolling reduction during the second drawing is more than or equal to 100 mm.
Further, annealing is carried out after the forging process is finished, and the annealing conditions are as follows: keeping the temperature for 12-14 h in an annealing furnace at 760 +/-10 ℃, and cooling to 100-300 ℃ at the temperature of 20-50 ℃/h.
The invention has the beneficial effects that: the flange material prepared by the method has the following mechanical properties: the yield strength sigma 0.2 is more than or equal to 415 MPa; the tensile strength sigma b is more than or equal to 585 MPa; the elongation delta is more than or equal to 20 percent; the reduction of area psi is more than or equal to 40 percent; the longitudinal impact energy Akv is more than or equal to 68J; the transverse impact energy is more than or equal to 41J; the hardness is less than or equal to 248 HB. According to the GB/T6402-20083 level requirement, the flaw detection rate reaches more than 92 percent. Besides excellent comprehensive mechanical properties, the material also has excellent normal temperature performance, excellent lasting and creeping performance below 650 ℃, low linear expansion coefficient and good manufacturability. The method has the advantages of stable process and quality, low cost and good benefit, and can be popularized and used in the field.
Detailed Description
The invention provides a preparation method of a flange material for nuclear power, which sequentially comprises the steps of electric furnace smelting, AOD refining, LF refining, VD refining, casting, forging and heat treatment, and then cooling to room temperature to obtain the flange material; normalizing at 1030-1080 ℃ for 4-5 h, tempering at 730-780 ℃ for 2-3 h.
Further, the steelmaking raw materials used in the electric furnace smelting process comprise at least one of chromium stainless steel return (Fe 80-85%, Cr 8-10%), low-phosphorus ferromolybdenum (Mo 73-77%, Fe 22-26%), ferrochromium (Cr 63-67%, Fe 28-32%), ferrovanadium (V48-52%, Fe 43-47%), ferroniobium (Nb 93-97%, Fe 3-5%) or ferroboron (B28-32%, Fe 63-67%).
Further, in the electric furnace smelting process, steel is tapped when the temperature of molten steel is more than 1650-1660 ℃. In the smelting process, steel is generally tapped at the temperature of 150-200 ℃ higher than the liquidus line of the smelting material, and the smelting material can be completely liquefied at the temperature of 1650-1660 ℃.
Further, in the AOD refining process, inert gas is blown into molten steel obtained by smelting in an electric furnace, wherein the inert gas is N2And Ar. Blowing N2And Ar at a pressure of 8-10 MPa, N2And the purity of Ar reaches 99.5-99.9%. Therefore, the content of N in a finished product of the material can be ensured to be 0.03-0.07%, the steel-making requirement is met, and in order to ensure the content of Cr in the decarburized steel, steel is tapped after the temperature in the furnace reaches 1670-1680 ℃.
Further, in the LF refining process, Al is added into the molten steel obtained after AOD refining, and the adding amount is that the mass of the Al accounts for 0.03 percent of the mass of the molten steel, so that impurities are removed through deoxidation. And after the slag is melted, adding LF refining slag in batches for reduction, adding 0.01-0.02% of carbon powder 30-60 min after the slag is placed into the furnace, keeping the reducing atmosphere, and adding 200 kg/furnace 80 refining slag or 350 kg/furnace 40 refining slag in batches according to the fluidity of the slag to obtain the steel slag.
Further, in the VD refining process, argon is blown into the steel slag obtained after LF refining. The argon blowing condition is as follows: the ultimate vacuum degree is lower than 67Pa, the argon blowing flow is 120-160 liters/minute, the holding time is longer than 18 minutes, and the argon blowing flow is reduced before breaking.
Further, the casting is started when the temperature of the steel slag obtained by the VD refining process is 1560 +/-5 ℃. The casting conditions are as follows: the ingot body pouring time is 12-15 minutes, the cap opening feeding time is 8-11 minutes, and the mold shaking time exceeds 12 hours.
Further, the forging process comprises twice upsetting and twice drawing, wherein the drawing adopts an FM method, and the forging specification is phi 500-700 mm.
Further, the specific flow of the forging process is as follows:
a. and quickly forging a steel ingot to a clamp handle, and chamfering and rounding. The forge piece is returned to 1240 +/-10 ℃ and is re-burnt for 45-90 min;
b. the first upsetting is carried out until the height H of the steel ingot is less than or equal to 1/2H0(H0The original height of the steel ingot); the upsetting adopts an upper arc tray and a lower arc tray. The width anvil of 500mm is adopted up and down during the first drawing, and the rolling reduction is more than or equal to 80 mm.
c. Upsetting for the second time until the height H of the steel ingot is less than or equal to 1/2H0(H0The original height of the steel ingot); the upsetting adopts an upper arc tray and a lower arc tray. Then forging into a large square, and compacting the center. And (4) returning the forge piece to 1230 +/-10 ℃, preserving the temperature for more than or equal to 2 hours, and then drawing out the forge piece to the specification of a finished product for the second time. Wherein, the second drawing length also adopts a 500mm wide anvil, and the rolling reduction is more than or equal to 100 mm.
In order to improve the plasticity, facilitate the processing deformation, improve the steel structure and improve the quality, the heating process strictly prevents the defects of overheating, overburning, uneven temperature, cracking and the like of the steel material. When the steel ingot is forged, the steel ingot is pressed down by a light hammer and is chamfered frequently to prevent forging crack. The annealing temperature is properly selected, and the heating and cooling speeds are not too high so as to prevent the forging from cracking due to stress concentration.
Further, annealing is carried out after the forging is finished, and the annealing conditions are as follows: keeping the temperature for 12-14 h in an annealing furnace at 760 +/-10 ℃, and cooling the annealing furnace to 100-300 ℃ at 20-50 ℃ for air cooling.
Further, the final heat treatment process of the flange material steel is normalizing and high-temperature tempering.
Wherein the normalizing temperature is 1030-1080 ℃. Normalizing is to improve the toughness of steel, crystal grains of the steel can be refined through normalizing, not only can satisfactory strength be obtained, but also toughness (AKv value) can be obviously improved, the comprehensive mechanical property of the material can be greatly improved, and the cutting performance is also improved.
The structure obtained by normalizing is lath-shaped martensite, and the structure is tempered after normalizing and is transformed into tempered martensite through tempering, so that the performance of the structure is superior to that of the lath-shaped martensite. The tempering temperature is 730-780 ℃, belonging to high-temperature tempering. When the tempering temperature is lower, the tempering effect is not obvious, and the elongation and impact values are lower; the strength of the steel is rather reduced with increasing tempering temperature. When the tempering temperature is too high (exceeding the AC1 line), the steel can be austenitized again and then re-hardened in the subsequent cooling process, and the mechanical property requirements of the flange material are not met.
Tempering is the most critical step for enabling the forged piece to become a qualified nuclear power flange material, and residual stress generated by the forged piece is eliminated through tempering, so that deformation and cracking are prevented; meanwhile, the hardness, strength, plasticity and toughness of the forging are adjusted to meet the requirement of service performance; in the process, the structure and the size can be stabilized, the precision of the flange material is ensured, and the processing performance is improved.
The required mechanical properties can be obtained only by the matching of normalizing and tempering. Through normalizing and tempering the forging, the comprehensive mechanical properties with better strength, plasticity and toughness can be obtained.
Preferably, the tempering temperature is 760 ℃. By adopting 760 ℃ tempering, although the strength index is reduced, the toughness index is obviously improved, and at the moment, the flange material steel for nuclear power has the best matching of strength and plastic toughness.
And (3) tempering the obtained tempered sorbite, namely the flange material for nuclear power.
The invention is further illustrated and described by the following examples and comparative examples.
Example 1
Smelting: 37000Kg of scrap steel (80-85% of Fe and 8-10% of Cr) is selected; 550Kg of low-phosphorus ferromolybdenum (Mo 73-77%, Fe 22-26%), 450-480 Kg of ferrochromium (Cr 63-67%, Fe 28-32%), 100Kg of ferrovanadium (V48-52%, Fe 43-47%), 22Kg of ferroniobium (Nb 93-97%, Fe 3-5%) or 10Kg of ferroboron (B28-32%, Fe 63-67%). The tapping temperature was 1650 ℃.
AOD：N2The Ar gas blowing system: and blowing nitrogen in the oxidation period, and blowing argon in the reduction period. The target temperature was set to 1680 ℃.
LF: feeding Al to 0.03%, adding steel slag in batches for reduction after the slag is melted, adding a small amount of carbon powder in the front period of the LF furnace to maintain the reducing atmosphere, adding 200 kg/furnace 80 refined slag in batches according to the fluidity of the slag, and adjusting chemical components according to target values.
VD: the slag thickness is 60mm, the maintaining time of the argon blowing flow rate of 120L/min is 18 minutes under the condition of the ultimate vacuum degree of 65Pa, and the argon blowing flow rate is adjusted to be small before breaking empty. The static blowing time is 15 minutes, and the casting temperature is 1560 +/-5 ℃.
Pouring: 13 ton ingot type, the ingot body pouring time is 12 minutes, the cap mouth feeding time is 8 minutes, and the die moving time is 12 hours.
Forging: 30 minutes before starting forging, the heating temperature is increased to 1250 ℃, round steel with the specification of phi 550mm is forged, and the round steel is formed by adopting a two-heading two-drawing (+ FM method): and quickly forging a steel ingot to a clamp handle, and chamfering and rounding. The reburning time is 90min at 1240 +/-10 ℃, and the upsetting height is from H02200mm upset to 1200 mm; the upsetting adopts an upper arc tray and a lower arc tray. The anvil with the width of 500mm is adopted up and down during the first drawing, and the rolling reduction is 80 mm. Then upsetting the height from 2000mm to 1200 mm; the upsetting adopts an upper arc tray and a lower arc tray. The secondary drawing also adopts a 500mm wide anvil, and the rolling reduction is 100 mm. Then forging into a large square, and compacting the center. Drawing and returning to the furnace at 1230 +/-10 ℃ for 2h, and then drawing to the specification of a finished product. Annealing: keeping the temperature for 14h in an annealing furnace at 760 +/-10 ℃, and cooling the annealing furnace by cooling the annealing furnace to 300 ℃ at 50 ℃.
And (3) heat treatment: the normalizing temperature is generally 1080 ℃, the tempering temperature is 760 ℃, and the tempering time is 2 h.
The non-metallic inclusions of the obtained forged steel part meet the following requirements:
class A is less than or equal to 1.5, class B is less than or equal to 1.5, class C is less than or equal to 1.0, class D is less than or equal to 1.0, and the sum of class A, class B and class C, D (calculated respectively in thickness) is less than or equal to 4.0.
And (3) appearance inspection: the forged steel piece has no visible defects such as cracks, folds and the like.
Ultrasonic flaw detection: according to the GB/T6402-20083 level requirement, the content of the compound reaches more than 92 percent.
Mechanical properties: after the flange material is subjected to normalizing at 1050 ℃ and high-temperature tempering at 760 ℃, test pieces are cut at the end heads, and the mechanical properties are tested as follows:
yield strength σ 0.2: 570 MPa; tensile strength σ b: 690 MPa; elongation δ: 24 percent; reduction of area ψ: 58 percent; longitudinal impact power Akv: 88J; lateral impact work Akv: 66J; hardness: 218 HB. And the relevant requirements are met.
Example 2
Smelting: 37000Kg of scrap steel (80-85% of Fe and 8-10% of Cr) is selected; 520Kg of low-phosphorus ferromolybdenum (73-77% Mo and 22-26% Fe), 480Kg of ferrochromium (63-67% Cr and 28-32% Fe), 100Kg of ferrovanadium (48-52% V and 43-47% Fe), 40Kg of ferroniobium (93-97% Nb and 3-5% Fe) or 10Kg of ferroboron (28-32% B and 63-67% Fe). The tapping temperature was 1650 ℃.
AOD：N2The Ar gas blowing system: and blowing nitrogen in the oxidation period, and blowing argon in the reduction period. The target temperature was set to 1670 ℃.
LF: feeding Al to 0.03%, adding steel slag in batches for reduction after the slag is melted, adding a small amount of carbon powder in the front period of the LF furnace to maintain the reducing atmosphere, adding 200 kg/furnace 80 refined slag in batches according to the fluidity of the slag, and adjusting chemical components according to target values.
VD: the slag thickness is 100mm, the argon blowing flow is kept for 22 minutes at 140 liters/minute under the condition of 70Pa of ultimate vacuum degree, and the argon blowing flow is adjusted to be small before breaking empty. The static blowing time is 15 minutes, and the casting temperature is 1560 +/-5 ℃.
Pouring: 13 ton ingot type, 15 minutes for casting ingot body, 11 minutes for feeding cap opening and 12 hours for moving die.
Forging: 30 minutes before starting forging, the heating temperature is increased to 1250 ℃, round steel with the specification of phi 550mm is forged, and the round steel is formed by adopting a two-heading two-drawing (+ FM method): and quickly forging a steel ingot to a clamp handle, and chamfering and rounding. The reburning time is 90min at 1240 +/-10 ℃, and the upsetting height is from H02200mm upset to 1200; the upsetting adopts an upper arc tray and a lower arc tray. The anvil with the width of 500mm is adopted up and down during the first drawing, and the rolling reduction is 80 mm. Then re-upset the height from H0Heading 2000mm to 1300; the upsetting adopts an upper arc tray and a lower arc tray. The secondary drawing also adopts a 500mm wide anvilThe rolling reduction was 100 mm. Then forging into a large square, and compacting the center. Drawing and returning to the furnace at 1230 +/-10 ℃ for 3h, and then drawing to the specification of a finished product. Annealing: keeping the temperature for 14h in an annealing furnace at 760 +/-10 ℃, and cooling the annealing furnace to 200 ℃ at the temperature of 20-50 ℃ for air cooling.
And (3) heat treatment: the normalizing temperature is generally 1080 ℃, the tempering temperature is 760 ℃, and the tempering time is 2 h.
The non-metallic inclusions meet the following requirements:
class A is less than or equal to 1.5, class B is less than or equal to 1.5, class C is less than or equal to 1.0, class D is less than or equal to 1.0, and the sum of class A, class B, class C and class D (calculated by the thickness respectively) is less than or equal to 4.0.
And (3) appearance inspection: the forged steel piece has no visible defects such as cracks, folds and the like.
Ultrasonic flaw detection: reaches more than 94 percent according to the GB/T6402-20083 level requirement.
Mechanical properties: after the flange material is subjected to normalizing at 1050 ℃ and high-temperature tempering at 760 ℃, test pieces are cut at the end heads, and the mechanical properties are tested as follows:
σ 0.2: 578 MPa; σ b: 696 MPa; elongation δ: 24.5 percent; reduction of area ψ: 57 percent; longitudinal impact power Akv: 86J; lateral impact work Akv: 64J; hardness: 220 HB. And the relevant requirements are met.

Claims (10)

1. The preparation method of the flange material for nuclear power is characterized by sequentially comprising the steps of electric furnace smelting, AOD refining, LF refining, VD refining, casting, forging and heat treatment, and then cooling to room temperature to obtain the flange material; wherein the process conditions of the heat treatment are as follows: normalizing at 1030-1080 ℃ for 4-5 h, tempering at 730-780 ℃ for 2-3 h.
2. The preparation method of the nuclear power flange material according to claim 1, wherein the nuclear power flange material comprises the following chemical components in percentage by mass: 0.08-0.12% of C, 0.30-0.60% of Mn, 0.20-0.50% of Si, 8.0-9.5% of Cr, less than or equal to 0.40% of Ni, 0.85-1.05% of Mo, 0.06-0.10% of Nb, less than or equal to 0.010% of S, less than or equal to 0.020% of P, 0.03-0.07% of N, 0.18-0.25% of V, less than or equal to 0.04% of Al, and the balance of inevitable impurities.
3. The method for preparing the flange material for nuclear power as claimed in any one of claims 1 or 2, wherein the steelmaking raw materials used in the electric furnace smelting process comprise: at least one of a chromium stainless steel return, low-phosphorus ferromolybdenum, ferrochromium, ferrovanadium, ferroniobium, or ferroboron; in the steelmaking raw materials, the chromium stainless steel return material contains 80-85% of Fe and 8-10% of Cr, the low-phosphorus ferromolybdenum contains 73-77% of Mo and 22-26% of Fe, the ferrochromium contains 63-67% of Cr and 28-32% of Fe, the ferrovanadium contains 48-52% of V and 43-47% of Fe, the ferroniobium contains 93-97% of Nb and 3-5% of Fe, and the ferroboron contains 28-32% of B and 63-67% of Fe.
4. The preparation method of the nuclear power flange material according to any one of claims 1 to 3, wherein the electric furnace smelting process meets the following conditions: tapping when the temperature of molten steel is 1650-1660 ℃;
the AOD refining process meets the following conditions: tapping when the temperature in the furnace reaches 1670-1680 ℃.
5. The preparation method of the nuclear power flange material according to any one of claims 1 to 4, wherein the LF refining process satisfies at least one of the following conditions:
adding aluminum accounting for 0.02-0.04 percent of the mass of the molten steel into the molten steel;
adding refining slag after the slag is melted, wherein the refining slag is 80 refining slag or 40 refining slag; the addition amount of the refining slag is 20-30 Kg/40 ton of molten steel;
adding carbon powder accounting for 0.01-0.02% of the mass of the molten steel 30-60 min after the molten steel is put into the furnace.
6. The preparation method of the nuclear power flange material according to any one of claims 1 to 5, wherein the VD refining process is to blow argon into the steel slag obtained after LF refining; the argon blowing condition satisfies at least one of the following conditions:
the ultimate vacuum degree is lower than 67 Pa;
the argon blowing flow is 120-160L/min;
the holding time is more than 18 min.
7. The preparation method of the nuclear power flange material according to any one of claims 1 to 6, characterized in that casting is started when the temperature of the steel slag obtained by VD refining is 1560 +/-5 ℃; the casting conditions satisfy at least one of the following:
pouring the ingot body for 12-15 min;
feeding time of the cap opening is 8-11 min;
the mold shaking time exceeded 12 h.
8. The preparation method of the nuclear power flange material according to claims 1 to 7, characterized in that the forging process comprises twice upsetting and twice drawing, the drawing adopts FM method, and the forging specification is phi 500-700 mm; the forging process comprises the following specific steps:
a. the first upsetting is carried out until the height H of the steel ingot is less than or equal to 1/2H0，H0The original height of the steel ingot; the rolling reduction is more than or equal to 80mm during the first drawing;
b. upsetting for the second time until the height H of the steel ingot is less than or equal to 1/2H0，H0The original height of the steel ingot; the rolling reduction during the second drawing is more than or equal to 100 mm.
9. The preparation method of the nuclear power flange material according to any one of claims 1 to 8, characterized by annealing after the forging process is finished, wherein the annealing conditions are as follows: keeping the temperature for 12-14 h in an annealing furnace at 760 +/-10 ℃, and cooling the annealing furnace to 100-300 ℃ at 20-50 ℃ for air cooling.
10. The flange material obtained by the preparation method of the nuclear power flange material as claimed in any one of claims 1 to 9.
CN202110678717.1A 2021-06-18 2021-06-18 Preparation method of flange material for nuclear power Pending CN113403524A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114959456A (en) * 2022-04-29 2022-08-30 江油市长祥特殊钢制造有限公司 Nuclear power SA182F91 valve body and preparation method thereof
CN117051333A (en) * 2023-10-12 2023-11-14 山西同航特钢有限公司 Forged steel supporting roller and preparation method thereof

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109112408A (en) * 2018-09-25 2019-01-01 成都先进金属材料产业技术研究院有限公司 The manufacturing method of the heat-resisting steel forgings of big specification P92
CN110218955A (en) * 2019-04-18 2019-09-10 江油市长祥特殊钢制造有限公司 The preparation method that SA182F92 prevents delta ferrite from generating

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109112408A (en) * 2018-09-25 2019-01-01 成都先进金属材料产业技术研究院有限公司 The manufacturing method of the heat-resisting steel forgings of big specification P92
CN110218955A (en) * 2019-04-18 2019-09-10 江油市长祥特殊钢制造有限公司 The preparation method that SA182F92 prevents delta ferrite from generating

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114959456A (en) * 2022-04-29 2022-08-30 江油市长祥特殊钢制造有限公司 Nuclear power SA182F91 valve body and preparation method thereof
CN117051333A (en) * 2023-10-12 2023-11-14 山西同航特钢有限公司 Forged steel supporting roller and preparation method thereof
CN117051333B (en) * 2023-10-12 2024-01-23 山西同航特钢有限公司 Forged steel supporting roller and preparation method thereof

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Application publication date: 20210917