CN113025777A - 30CrNi2MoVA large-size forged material and preparation method thereof - Google Patents

30CrNi2MoVA large-size forged material and preparation method thereof Download PDF

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Publication number
CN113025777A
CN113025777A CN202110229174.5A CN202110229174A CN113025777A CN 113025777 A CN113025777 A CN 113025777A CN 202110229174 A CN202110229174 A CN 202110229174A CN 113025777 A CN113025777 A CN 113025777A
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less
equal
forged material
forging
furnace
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易文
张宇
师宇
康禹
朱华
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Pangang Group Jiangyou Changcheng Special Steel Co Ltd
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Pangang Group Jiangyou Changcheng Special Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/52—Manufacture of steel in electric furnaces
    • 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
    • B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
    • B21J5/08—Upsetting
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/076—Use of slags or fluxes as treating agents
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • 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
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • 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
    • C22C38/18—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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention provides a preparation method of a 30CrNi2MoVA large-size forged material, which comprises the following steps: smelting the alloy raw materials by adopting electric furnace smelting, LF external refining and VD refining in sequence to obtain alloy liquid; pouring the alloy liquid to obtain a steel ingot; and forging the steel ingot and then tempering to obtain a forged material. By adopting the method provided by the invention, the standard 30CrNi2MoVA large-size forged material can be produced, and the internal structure, the performance and the inclusion of the forged material can meet the standard requirements. The invention also provides a 30CrNi2MoVA large-size forged material.

Description

30CrNi2MoVA large-size forged material and preparation method thereof
Technical Field
The invention belongs to the technical field of iron-based alloy structural steel, and particularly relates to a 30CrNi2MoVA large-size forged material and a preparation method thereof.
Background
The 30CrNi2MoVA steel has high yield strength and impact toughness after heat treatment, good hardenability and small deformation during quenching; the cutting processing performance is good, the comprehensive mechanical property is high, and the composite material is an important structural member mainly used for bearing large impact load and vibration. The performance requirements of the 30CrNi2MoVA large forged material are that the mechanical properties are as follows: rm is more than or equal to 855 MPa; r0.2 is more than or equal to 735 MPa; a% is more than or equal to 15; z% is more than or equal to 45; AKV8(-20 deg.C) is not less than 42. Ingot type segregation, wherein the general loose center porosity is less than or equal to 2.0; general point-like segregation and edge point-like segregation are not allowed. Flaw detection inspection: the ultrasonic flaw detection of the steel is carried out one by one according to the GB/T6402-2008 standard, and the defects of white spots, cracks, shrinkage cavities and the like are not allowed; the defect smaller than phi 2mm is ignored, the dense defect is not allowed to exist, the defect with the single dispersed equivalent diameter of phi 2-4 mm is allowed to exist, the distance between adjacent defects is 10 times larger than that of the larger defect and is 100cm2The equivalent diameter phi 2-4 mm in area is not more than 3 defects. The main performance indexes of the large-specification 30CrNi2MoVA forged material (not less than phi 500mm) are low-power, mechanical property and internal quality of flaw detection, and the standard requirement is not easy to meet due to large specification.
Disclosure of Invention
In view of the above, the invention aims to provide a 30CrNi2MoVA large-size forged material and a preparation method thereof, and the 30CrNi2MoVA large-size forged material prepared by the method provided by the invention has good quality and high yield.
The invention provides a preparation method of a 30CrNi2MoVA large-size forged material, which comprises the following steps:
smelting the alloy raw materials by adopting electric furnace smelting, LF external refining and VD refining in sequence to obtain alloy liquid;
pouring the alloy liquid to obtain a steel ingot;
and forging the steel ingot and then tempering to obtain a forged material.
Preferably, in the VD refining process, before vacuumizing, Al wires are fed according to 0.05-0.07% of the mass of the alloy liquid.
Preferably, the alloy liquid comprises the following components:
0.27 to 0.31 wt% of C;
0.85-0.95 wt% Mn;
0.20 to 0.35 wt% of Si;
1.80-1.90 wt% of Ni;
0.8-0.9 wt% Cr;
0.37 to 0.45 wt% of Mo;
0.05 to 0.15 wt% of V;
less than or equal to 0.0002 wt% of H;
o is less than or equal to 0.0015 weight percent;
p is less than or equal to 0.015wt percent;
less than or equal to 0.005 wt% of S;
cu of less than or equal to 0.20 wt%;
the balance being Fe.
Preferably, the forging process adopts a processing mode of three times of upsetting and drawing.
Preferably, the height of each upsetting in the three-upsetting process is less than or equal to 1/2H 0.
Preferably, the tapping temperature in the electric furnace smelting process is 1650-1690 ℃.
Preferably, the Al content is adjusted to 0.05-0.06 wt% before tapping in the LF external refining process.
Preferably, rare earth is added after the vacuum is broken in the VD refining process.
The invention provides a 30CrNi2MoVA large-size forged material prepared by the method in the technical scheme.
Preferably, the diameter of the 30CrNi2MoVA large-size forged material is more than or equal to 500 mm.
The method provided by the invention can produce the 30CrNi2MoVA large forged material meeting the requirements of users and protocols; before VD evacuation, feeding Al wires according to 0.05-0.07% to ensure good deoxidation and obtain the required total aluminum content in the steel, and then matching with a refining slag system to ensure that the steel obtains low gas content and inclusion level and ensures the internal quality of the steel; the forging material has good mechanical properties through reasonable internal component control; the forging of the invention adopts a processing mode of three times of upsetting and drawing, which can meet the requirements of low power and flaw detection standards; the invention can fully utilize the existing equipment, has simple process and strong practicability, and the produced steel has good quality and is approved by users.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other examples, which may be modified or appreciated by those of ordinary skill in the art based on the examples given herein, are intended to be within the scope of the present invention. It should be understood that the embodiments of the present invention are only for illustrating the technical effects of the present invention, and are not intended to limit the scope of the present invention. In the examples, the methods used were all conventional methods unless otherwise specified.
The invention provides a preparation method of a 30CrNi2MoVA large-size forged material, which comprises the following steps:
smelting the alloy raw materials by adopting electric furnace smelting, LF external refining and VD refining in sequence to obtain alloy liquid;
pouring the alloy liquid to obtain a steel ingot;
and forging the steel ingot and then tempering to obtain a forged material.
In the invention, lime is preferably padded at the bottom of the furnace before charging in the electric furnace smelting process, and the mass of the lime is preferably 700-900 kg, more preferably 750-850 kg, and most preferably 800 kg.
In the invention, in the electric furnace smelting process, the sampling is preferably carried out for full analysis (component analysis) when the temperature is more than or equal to 1540 ℃, more preferably 1540-1560 ℃, more preferably 1545-1555 ℃, and most preferably 1550 ℃.
In the invention, the tapping conditions in the electric furnace smelting process are preferably that the end point carbon content is more than or equal to 0.05 wt%, and the P content is less than or equal to 0.012 wt%; the end point carbon content is preferably 0.05-0.06%, and more preferably 0.055%; the content of P is preferably 0.001-0.012%, more preferably 0.005-0.010%, and most preferably 0.006-0.008%; the tapping temperature is preferably 1650-1690 ℃, more preferably 1660-1680 ℃ and most preferably 1670 ℃.
In the invention, the charging temperature in the LF external refining process is preferably not less than 1540 ℃, more preferably 1540-1560 ℃, more preferably 1545-1555 ℃, and most preferably 1550 ℃.
In the invention, Al wires are preferably fed and steel slag and C powder are preferably added in the LF external refining process; the addition amount of the Al wire is preferably 95-105 m/furnace, and more preferably 100 m/furnace; the addition amount of the steel slag is preferably 45-55 Kg/furnace, more preferably 48-52 Kg/furnace, and most preferably 50 Kg/furnace; the adding amount of the carbon powder is preferably 40-50 Kg/furnace, more preferably 42-48 Kg/furnace, and most preferably 44-46 Kg/furnace.
In the invention, the Al content is preferably adjusted to 0.05-0.06 wt%, and more preferably 0.055 wt% before tapping in the LF external refining process.
In the invention, the tapping condition in the LF external refining process is preferably that the content of S is less than or equal to 0.006 wt%, more preferably 0-0.006 wt%, more preferably 0.001-0.005 wt%, more preferably 0.002-0.004 wt%, and most preferably 0.003 wt%; the contents of other alloy elements meet the requirements of the pre-obtained alloy components.
In the invention, aluminum wires are preferably fed into the molten alloy in the VD refining process to ensure good deoxidation.
In the invention, the adding amount of the aluminum wire is preferably 0.05-0.07% of the mass of the alloy liquid, and more preferably 0.06%.
In the invention, the ultimate vacuum degree in the VD refining process is preferably less than or equal to 67Pa, more preferably 0-67 Pa, more preferably 10-60 Pa, more preferably 20-50 Pa, more preferably 30-40 Pa, and most preferably 35 Pa; the retention time of the ultimate vacuum degree in the VD refining process is preferably not less than 15min, more preferably 15-20 min, and most preferably 16-18 min.
In the invention, rare earth is preferably added and Ar is blown statically after the vacuum breaking in the VD refining process.
In the invention, the addition amount of the rare earth is preferably 0.04-0.06% of the mass of the alloy liquid, and more preferably 0.05%.
In the invention, the time for statically blowing Ar is preferably not less than 15min, more preferably 15-20 min, and most preferably 16-18 min.
In the invention, the optimal ultimate vacuum degree in the VD refining process is less than or equal to 67Pa, Ar is blown under the ultimate vacuum at a large flow rate, the holding time is more than or equal to 15min, H is determined after the vacuum breaking, and the H content is less than or equal to 0.0002 wt%; the flow rate of Ar blowing is preferably more than or equal to 120L/min, more preferably 120-150L/min, and most preferably 130-140L/min; the content of H is preferably 0 to 0.00020 wt%, more preferably 0.0001 wt%.
In the invention, the composition of the alloy liquid is preferably controlled in the smelting process, and the composition of the alloy liquid is preferably as follows:
0.27 to 0.31 wt% of C;
0.85-0.95 wt% Mn;
0.20 to 0.35 wt% of Si;
1.80-1.90 wt% of Ni;
0.8-0.9 wt% Cr;
0.37 to 0.45 wt% of Mo;
0.05 to 0.15 wt% of V;
less than or equal to 0.0002 wt% of H;
o is less than or equal to 0.0015 weight percent;
p is less than or equal to 0.015wt percent;
less than or equal to 0.005 wt% of S;
cu of less than or equal to 0.20 wt%;
the balance being Fe.
In the invention, the mass content of C is preferably 0.28-0.3%, more preferably 0.29%; the mass content of Mn is preferably 0.88-0.92%, and more preferably 0.90%; the mass content of Si is preferably 0.25-0.3%, more preferably 0.26-0.28%, and most preferably 0.27%; the mass content of the Ni is preferably 1.82-1.88%, more preferably 1.84-1.86%, and most preferably 1.85%; the mass content of Cr is preferably 0.82-0.88%, more preferably 0.84-0.86%, and most preferably 0.85%; the mass content of Mo is preferably 0.38-0.42%, more preferably 0.39-0.41%, and most preferably 0.40%; the mass content of V is preferably 0.08-0.12%, and more preferably 0.1%; the mass content of H is preferably 0.0001-0.0002%; the mass content of O is preferably 0.001-0.0015%, more preferably 0.0011-0.0014%, and most preferably 0.0012-0.0013%; the mass content of the P is preferably 0.01-0.015%, more preferably 0.011-0.014%, and most preferably 0.012-0.013%; the mass content of S is preferably 0.001-0.005%, more preferably 0.002-0.004%, and most preferably 0.003%; the mass content of Cu is preferably 0.1-0.15%.
The invention preferably controls the components of the alloy liquid to obtain a product with good mechanical property.
In the invention, the casting powder is preferably added in the casting process; the addition amount of the covering slag is preferably 2-3 Kg/t of alloy liquid, and more preferably 2.5Kg/t of alloy liquid; the casting powder is preferably large steel ingot casting powder, such as XBDD-6 casting powder; the mold flux preferably includes:
8-15 wt% of C solids;
10-20 wt% of CaO;
15 to 45 wt% of SiO2；
9-15 wt% of Al2O3。
In the invention, the mass content of the C solid is preferably 9-14%, more preferably 10-13%, and most preferably 11-12%; the mass content of CaO is preferably 12-18%, more preferably 14-16%, and most preferably 15%; the SiO2The mass content of (b) is preferably 20 to 40%, more preferably 25 to 35%, most preferably 30%; the Al is2O3The content of (b) is preferably 10 to 14% by mass, more preferably 11 to 13% by mass, most preferably 12% by mass.
In the invention, a heat generating agent is preferably added in the casting process; the addition amount of the heat generating agent is preferably 2-4 Kg/t of alloy liquid, more preferably 2.5-3.5 Kg/t of alloy liquid, and most preferably 3Kg/t of alloy liquid; the preferred heating agent is a large steel ingot heating agent (XBBFRJ-20) MAL which is more than or equal to 20 percent.
In the invention, Ar gas protection pouring is preferably adopted in the pouring process.
In the invention, the casting time in the casting process is preferably 10-13 min, and more preferably 11-12 min; the filling time of the molten metal in the pouring process is preferably not less than 8min, and more preferably 9-10 min.
In the present invention, the mass of the steel ingot is preferably 8 to 13 tons, more preferably 9 to 12 tons, and most preferably 10 to 11 tons.
In the invention, the ingot is preferably subjected to red conveying before forging, and the temperature of the red conveying is preferably equal to or more than 500 ℃, more preferably 600-700 ℃, more preferably 630-670 ℃, and most preferably 650 ℃.
In the present invention, the method of red sending preferably comprises:
and sequentially carrying out steel ingot pouring, loading, transporting, cap removing, demoulding and furnace loading.
In the invention, the loading time is preferably less than or equal to 35min, more preferably 20-35 min, and most preferably 25-30 min. In the invention, the transportation time is preferably less than or equal to 80min, more preferably 60-80 min, more preferably 65-75 min, and most preferably 70 min. In the invention, the charging time is preferably less than or equal to 60min, more preferably 45-60 min, and more preferably 50-55 min.
In the invention, the forging preferably adopts a three-time upsetting-drawing mode to forge the steel ingot into a material by using a press so as to meet the requirements of low power and flaw detection standards.
In the invention, the three upsetting-drawing refers to the fact that three upsetting and three drawing-out are required to be completed in the forging process; the height of each upsetting is preferably not more than 1/2H0(H0 is the original height of the steel ingot), more preferably 0.1-0.5H 0, more preferably 0.2-0.4H 0, and most preferably 0.3H 0.
In the invention, the elongation is preferably elongated by adopting an FM forging mode; drawing to the desired size is preferably performed using a press forming with a V-anvil or a ram.
In the present invention, the press is preferably a 4500KN press.
In the invention, the temperature in the forging process is preferably 1150-1250 ℃, more preferably 1180-1220 ℃, and most preferably 1200 ℃ or 1205 ℃; the heat preservation time in the forging process is preferably not less than 5 hours, more preferably 5-7 hours, and most preferably 6 hours.
In the invention, the forging temperature in the forging process is preferably not less than 1050 ℃, more preferably 1050-1150 ℃, more preferably 1080-1130 ℃, and most preferably 1100-1120 ℃; the finish forging temperature is preferably not less than 850 ℃, more preferably 850-900 ℃, and most preferably 860-880 ℃.
In the present invention, the forging preferably further comprises:
and slowly cooling the forged product and then tempering.
In the present invention, the slow cooling method preferably includes:
and (4) furnace cooling the forged product until the temperature is less than or equal to 200 ℃, and then tempering.
In the invention, the temperature of the furnace cooling is preferably 0-200 ℃, more preferably 50-150 ℃, more preferably 80-120 ℃, and most preferably 100 ℃.
In the present invention, the tempering method preferably includes:
heating the product cooled in the furnace, preserving heat and cooling.
In the invention, the heating temperature is preferably 650-750 ℃, and more preferably 680-720 ℃; the heat preservation time is preferably 20-30 hours, more preferably 22-28 hours, and most preferably 24-26 hours.
In the present invention, the method of cooling preferably comprises:
and cooling the heat-preserved product in the furnace, and then discharging the product from the furnace for air cooling.
In the invention, the speed of cooling in the furnace is preferably 25-35 ℃/h, more preferably 28-32 ℃/h, and most preferably 30 ℃/h; the cooling in the furnace is preferably carried out to 320-380 ℃, more preferably 330-370 ℃, more preferably 340-360 ℃ and most preferably 350 ℃.
In the present invention, the tempering preferably further comprises:
and straightening, polishing, detecting a flaw and coping the tempered product to obtain the forged material.
In the present invention, the straightening process preferably includes:
the blank is flatly laid on a feeding rack, the feeding rack automatically sends the blanks to a material conveying rotary roller way one by one in sequence, the material conveying rotary roller way automatically sends the blanks to a straightening machine for straightening, and the material conveying rotary roller way automatically sends the blanks to a discharging rack.
In the invention, the bending degree of the finished product material in the correcting process is preferably not more than 3mm per meter, and more preferably not more than 1-3 mm per meter.
The invention provides a 30CrNi2MoVA large-size forged material prepared by the method in the technical scheme.
In the invention, the components of the 30CrNi2MoVA large-size forging material are consistent with those of the alloy liquid in the technical scheme, and are not described again.
In the invention, the diameter of the 30CrNi2MoVA large-size forged material is preferably not less than 500mm, more preferably 500-600 mm, and most preferably 550 mm.
The method provided by the invention can produce the 30CrNi2MoVA large forged material meeting the requirements of users and protocols; before VD evacuation, feeding Al wires according to 0.05-0.07% to ensure good deoxidation and obtain the required total aluminum content in the steel, and then matching with a refining slag system to ensure that the steel obtains low gas content and inclusion level and ensures the internal quality of the steel; the forging material has good mechanical properties through reasonable internal component control; the forging of the invention adopts a processing mode of three times of upsetting and drawing, which can meet the requirements of low power and flaw detection standards; the invention can fully utilize the existing equipment, has simple process and strong practicability, and the produced steel has good quality and is approved by users.
Example 1
Smelting the alloy raw materials by adopting electric furnace smelting, LF external refining and VD refining in sequence to obtain alloy liquid;
pouring the alloy liquid to obtain a steel ingot;
forging the steel ingot and then tempering to obtain a forged material;
before charging in the electric furnace smelting process, lime is padded at the bottom of the furnace, and the mass of the lime is 800 kg; sampling at 1550 ℃ for full analysis (component analysis), wherein the end point carbon content in tapping is 0.055 wt%, and the P content is 0.005 wt%; the tapping temperature is 1670 ℃;
feeding Al wires and adding steel slag and C powder at the tank-feeding temperature of 1560 ℃ in the LF external refining process; the adding amount of the Al wire is 100 m/furnace; the adding amount of the steel slag is 50 Kg/furnace; the adding amount of the carbon powder is 45 Kg/furnace; adjusting the Al content to 0.06 wt% before tapping;
in the invention, the content of S in tapping in the LF external refining process is 0.003 wt%; the content of other alloy elements meets the component requirements of the pre-obtained alloy;
the ultimate vacuum degree in the VD refining process is 25Pa, Ar is blown under the ultimate vacuum at a large flow rate, the flow rate of the blown Ar is 120L/min, and the retention time of the ultimate vacuum degree is 16 min; after the vacuum is broken in the VD refining process, adding rare earth and statically blowing Ar, wherein the adding amount of the rare earth is 0.05 percent of the mass of the alloy liquid, and the time for statically blowing Ar is 15 min; h is determined after the air is broken, and the content of H is 0.0001 weight percent; the components of the alloy liquid are controlled in the smelting process as follows: 0.27 to 0.31 wt% of C; 0.85-0.95 wt% Mn; 0.20 to 0.35 wt% of Si; 1.80-1.90 wt% of Ni; 0.8-0.9 wt% Cr; 0.37 to 0.45 wt% of Mo; 0.05 to 0.15 wt% of V; less than or equal to 0.0002 wt% of H; o is less than or equal to 0.0015 weight percent; p is less than or equal to 0.015wt percent; less than or equal to 0.005 wt% of S; the balance being Fe;
adding large steel ingot casting powder (XBDD-6) in the casting process; the addition amount of the covering slag is 2.5Kg/t of alloy liquid; adding a large steel ingot heating agent (XBBFRJ-20) in the casting process; the adding amount of the heating agent is 3Kg/t of alloy liquid; ar gas is adopted for protection pouring in the pouring process; and the pouring time in the pouring process is 11min, and the metal liquid filling time is 9min, so that 13t of octagonal ingots are obtained.
Carrying out red sending on the octagonal ingot, and then forging, wherein the temperature of the red sending is 650 ℃, and the red sending comprises the following steps: sequentially carrying out steel ingot pouring, loading, transporting, cap removing, demoulding and furnace loading; the loading time is 33min, the transportation time is 78min, and the charging time is 58 min.
Forging the steel ingot into a material by using a press in a three-time upsetting-drawing mode, wherein three-time upsetting and three-time drawing are required to be completed in the forging process; the upsetting height is 0.4H0 each time, and the length is drawn out by adopting an FM forging mode; adopting a 4500KN press; forging at 1200 ℃ for 6h, wherein the forging temperature is 1080 ℃ and the finish forging temperature is 880 ℃.
After forging, furnace cooling is carried out on the forged product, the furnace cooling is carried out until the temperature is 180 ℃, and then tempering is carried out, wherein the tempering comprises the following steps: heating the product cooled in the furnace, preserving heat, and cooling, wherein the heating temperature is 680 ℃, the heat preservation time is 24 hours, and the cooling method comprises the following steps: and cooling the heat-preserved product in a furnace to 350 ℃, then discharging the product from the furnace for air cooling, wherein the cooling speed in the furnace is 30 ℃/h.
Straightening, polishing, detecting a flaw and coping a product discharged from the furnace and subjected to air cooling to obtain a forged material; the straightening comprises the following steps: the method comprises the following steps of (1) flatly paving blanks on a feeding rack, wherein the feeding rack automatically sends the blanks to a material conveying rotary roller way one by one in sequence, the material conveying rotary roller way automatically sends the blanks to a straightening machine for straightening, and the material conveying rotary roller way automatically sends the blanks to a blanking rack; and the bending degree of the finished product material in the correcting process is not more than 3mm per meter.
The components of the forging material prepared in the embodiment 1 of the invention are detected according to GB/T223 chemical analysis method of steel and alloy, and the detection result is as follows: 0.29 wt% of C, 0.90 wt% of Mn, 0.25 wt% of Si, 0.006 wt% of P, 0.003 wt% of S, 0.86 wt% of Cr, 0.41 wt% of Mo, 1.82 wt% of Ni, 0.10 wt% of Cu, 0.09 wt% of V, 0.0013 wt% of O, 0.0001 wt% of H and the balance of Fe.
The performance of the forged material prepared in the embodiment 1 of the invention is detected according to GB/T226-2015 'macrostructure and defect acid etching inspection method for steel', and the detection result is as follows: segregation is 0.5, general looseness is 0.5, and central looseness is less than or equal to 1.0; generally point-like segregation and edge point-like segregation of 0 order.
The performance of the forged material prepared in the embodiment 1 of the invention is detected according to GB/T228-2002 metal material room temperature tensile test method and GB/T229-1994 metal Charpy notched impact test method, and the detection result is as follows: rm 1012 MPa; R0.2926MPa; 20.5 percent of A; z% 64%; AKV8(-20 ℃ C.) 848487J.
Example 2
Smelting the alloy raw materials by adopting electric furnace smelting, LF external refining and VD refining in sequence to obtain alloy liquid;
pouring the alloy liquid to obtain a steel ingot;
forging the steel ingot and then tempering to obtain a forged material;
before charging in the electric furnace smelting process, lime is padded at the bottom of the furnace, and the mass of the lime is 800 kg; sampling at 1560 deg.C, and performing total analysis (component analysis), wherein the final carbon content is 0.05 wt% and P content is 0.005 wt% during tapping; the tapping temperature is 1660 ℃;
feeding Al wires and adding steel slag and C powder at the temperature of 1555 ℃ in the LF external refining process; the adding amount of the Al wire is 102 m/furnace; the adding amount of the steel slag is 52Kg per furnace; the adding amount of the carbon powder is 45 Kg/furnace; adjusting the Al content to 0.065 wt% before tapping;
in the invention, the content of S in tapping in the LF external refining process is 0.003 wt%; the content of other alloy elements meets the component requirements of the pre-obtained alloy;
the ultimate vacuum degree in the VD refining process is 30Pa, Ar is blown under the ultimate vacuum at a large flow rate, the flow rate of the blown Ar is 125L/min, and the retention time of the ultimate vacuum degree is 17 min; after the vacuum is broken in the VD refining process, adding rare earth and statically blowing Ar, wherein the adding amount of the rare earth is 0.05 percent of the mass of the alloy liquid, and the time for statically blowing Ar is 16 min; determining H after the air is broken, wherein the content of H is 0.00005 wt%; the components of the alloy liquid are controlled in the smelting process as follows: 0.27 to 0.31 wt% of C; 0.85-0.95 wt% Mn; 0.20 to 0.35 wt% of Si; 1.80-1.90 wt% of Ni; 0.8-0.9 wt% Cr; 0.37 to 0.45 wt% of Mo; 0.05 to 0.15 wt% of V; less than or equal to 0.0002 wt% of H; o is less than or equal to 0.0015 weight percent; p is less than or equal to 0.015wt percent; less than or equal to 0.005 wt% of S; the balance being Fe;
adding large steel ingot casting powder (XBDD-6) in the casting process; the addition amount of the covering slag is 2.5Kg/t of alloy liquid; adding a large steel ingot heating agent (XBBFRJ-20) in the casting process; the adding amount of the heating agent is 3Kg/t of alloy liquid; ar gas is adopted for protection pouring in the pouring process; and the pouring time in the pouring process is 12min, and the metal liquid filling time is 9min, so that 13t of octagonal ingots are obtained.
Carrying out red sending on the octagonal ingot, and then forging, wherein the temperature of the red sending is 650 ℃, and the red sending comprises the following steps: sequentially carrying out steel ingot pouring, loading, transporting, cap removing, demoulding and furnace loading; the loading time is 34min, the transportation time is 76min, and the furnace charging time is 57 min.
Forging the steel ingot into a material by using a press in a three-time upsetting-drawing mode, wherein three-time upsetting and three-time drawing are required to be completed in the forging process; the upsetting height is 0.5H0 each time, and the length is drawn out by adopting an FM forging mode; adopting a 4500KN press; the forging is carried out at the temperature of 1205 ℃ for 6.5h, the open forging temperature is 1085 ℃, and the finish forging temperature is 870 ℃.
After forging, furnace cooling is carried out on the forged product, the furnace cooling is carried out until the temperature is 160 ℃, and then tempering is carried out, wherein the tempering comprises the following steps: heating the product cooled in the furnace, preserving heat, and cooling, wherein the heating temperature is 680 ℃, the heat preservation time is 24 hours, and the cooling method comprises the following steps: and cooling the heat-preserved product in a furnace to 350 ℃, then discharging the product from the furnace for air cooling, wherein the cooling speed in the furnace is 30 ℃/h.
Straightening, polishing, detecting a flaw and coping a product discharged from the furnace and subjected to air cooling to obtain a forged material; the straightening comprises the following steps: the method comprises the following steps of (1) flatly paving blanks on a feeding rack, wherein the feeding rack automatically sends the blanks to a material conveying rotary roller way one by one in sequence, the material conveying rotary roller way automatically sends the blanks to a straightening machine for straightening, and the material conveying rotary roller way automatically sends the blanks to a blanking rack; and the bending degree of the finished product material in the correcting process is not more than 3mm per meter.
The forged material prepared in example 2 of the present invention was subjected to composition measurement according to the method of example 1, and the measurement results were: 0.28 wt% of C, 0.87 wt% of Mn, 0.26 wt% of Si, 0.006 wt% of P, 0.003 wt% of S, 0.83 wt% of Cr, 0.41 wt% of Mo, 1.84 wt% of Ni, 0.09 wt% of Cu, 0.09 wt% of V, 0.0014 wt% of O, 0.00005 wt% of H and the balance of Fe.
According to the method of the embodiment 1, the forged material prepared in the embodiment 2 of the invention is subjected to performance detection, and the detection result is as follows: segregation is 0.5, general looseness is 1.0, and central looseness is less than or equal to 1.0; general point segregation and edge point segregation of grade 0; rm 993 MPa; R0.2902MPa; a% is 23%; z% 62%; AKV8(-20 ℃ C.) 828592J.
The method provided by the invention can produce the 30CrNi2MoVA large forged material meeting the requirements of users and protocols; before VD evacuation, feeding Al wires according to 0.05-0.07% to ensure good deoxidation and obtain the required total aluminum content in the steel, and then matching with a refining slag system to ensure that the steel obtains low gas content and inclusion level and ensures the internal quality of the steel; the forging material has good mechanical properties through reasonable internal component control; the forging of the invention adopts a processing mode of three times of upsetting and drawing, which can meet the requirements of low power and flaw detection standards; the invention can fully utilize the existing equipment, has simple process and strong practicability, and the produced steel has good quality and is approved by users.
While only the preferred embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims (10)

1. A preparation method of a 30CrNi2MoVA large-size forged material comprises the following steps:
smelting the alloy raw materials by adopting electric furnace smelting, LF external refining and VD refining in sequence to obtain alloy liquid;
pouring the alloy liquid to obtain a steel ingot;
and forging the steel ingot and then tempering to obtain a forged material.
2. The method according to claim 1, wherein during the VD refining process, Al wires are fed according to 0.05-0.07 percent of the mass of the molten alloy before vacuumizing.
3. The method according to claim 1, wherein the alloy liquid has a composition of:
0.27 to 0.31 wt% of C;
0.85-0.95 wt% Mn;
0.20 to 0.35 wt% of Si;
1.80-1.90 wt% of Ni;
0.8-0.9 wt% Cr;
0.37 to 0.45 wt% of Mo;
0.05 to 0.15 wt% of V;
less than or equal to 0.0002 wt% of H;
o is less than or equal to 0.0015 weight percent;
p is less than or equal to 0.015wt percent;
less than or equal to 0.005 wt% of S;
cu of less than or equal to 0.20 wt%;
the balance being Fe.
4. The method of claim 1, wherein three upsetting operations are used in the forging process.
5. The method of claim 4, wherein each upset during said three upsets is 1/2H0 height ≦ for each upset.
6. The method according to claim 1, wherein the tapping temperature during the electric furnace smelting is 1650-1690 ℃.
7. The method as claimed in claim 1, wherein the Al content is adjusted to 0.05-0.06 wt% before tapping in the LF external refining process.
8. The method according to claim 1, wherein rare earth is added after the space is broken in the VD refining process.
9. A 30CrNi2MoVA large gauge wrought product prepared by the method of claim 1.
10. The 30CrNi2MoVA large-size forged material of claim 9, wherein the diameter of the 30CrNi2MoVA large-size forged material is not less than 500 mm.
CN202110229174.5A 2021-03-02 2021-03-02 30CrNi2MoVA large-size forged material and preparation method thereof Pending CN113025777A (en)

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Application publication date: 20210625