CN116694996A - FAS3420RH gear steel and production method thereof - Google Patents

FAS3420RH gear steel and production method thereof Download PDF

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Publication number
CN116694996A
CN116694996A CN202310735001.XA CN202310735001A CN116694996A CN 116694996 A CN116694996 A CN 116694996A CN 202310735001 A CN202310735001 A CN 202310735001A CN 116694996 A CN116694996 A CN 116694996A
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steel
percent
equal
less
rolling
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李超群
赵千水
卢秉军
童家阁
曹羽
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Bengang Steel Plates Co Ltd
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Bengang Steel Plates 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
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
    • B21B45/08—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing hydraulically
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • 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
    • 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
    • C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
    • 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
    • C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • 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
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires 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
    • C22C33/06—Making ferrous alloys by melting using master 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
    • C22C38/04—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
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • 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
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • 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

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  • Physics & Mathematics (AREA)
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  • Crystallography & Structural Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The invention discloses FAS3420RH gear steel and a production method thereof, and belongs to the technical field of steel preparation. The FAS3420RH gear steel comprises the following chemical components in percentage by mass: 0.19 to 0.24 percent of C, 0.20 to 0.30 percent of Si, 0.80 to 0.88 percent of Mn, less than or equal to 0.025 percent of P, 0.020 to 0.035 percent of S, 0.58 to 0.63 percent of Cr, 0.58 to 0.62 percent of Ni, 0.15 to 0.25 percent of Mo, and Cu: 0.08% or less, alt 0.010-0.045%, V0.02%, ti 0.02%, sn 0.05%, nb 0.02%, B0.0008%, O0.0015%, and Fe and unavoidable impurities as the rest; the FAS3420RH gear steel produced by the method is obtained through smelting by an EBT electric furnace, refining by an LF furnace, refining by a VD furnace, continuous casting, heat preservation, heating, rolling, slow cooling and annealing, and the terminal hardenability meets the following conditions: j6 The isothermal annealing band-shaped structure is less than or equal to 2.5 grades, the good processing performance and the service life of the material are ensured, and the continuous casting furnace number can reach 15 furnaces.

Description

FAS3420RH gear steel and production method thereof
Technical Field
The invention belongs to the technical field of steel preparation, and particularly relates to steel for a heavy-duty car gear and a production method thereof.
Background
The gear is an important transmission part, and the material of the gear has a direct influence on the service life of the gear. The gear steel of the gear box has good toughness and wear resistance, bears impact, bending and contact stress, and also has the advantages of small deformation, high precision and low noise. FAS3420RH is a CrNiMo gear steel, is used for a heavy truck 12-gear gearbox gear, has higher hardenability, has good toughness and can well bear impact and bending fatigue stress.
The band structure is a structure in which a band mainly composed of proeutectoid ferrite and a band mainly composed of pearlite are stacked on each other, which are formed along the rolling direction of the steel material. The strip-shaped structure is a common structure defect formed in the casting blank hot rolling process, and the strip-shaped structure enables the mechanical property of the steel to be anisotropic, so that the transverse plasticity, the toughness and the area reduction rate of the steel are reduced. Meanwhile, due to the existence of the banded tissue, the gear can deform after heat treatment, and the dimensional accuracy and the fatigue life of the gear are seriously affected.
FAS3420RH has more strict requirements on the strip structure of the steel after isothermal annealing, and if the heat treatment process is not properly controlled, proeutectoid ferrite is fully separated out to form a wider ferrite strip, so that the strip structure is difficult to control.
Disclosure of Invention
In view of the above, the present invention aims to provide FAS3420RH gear steel and a method for producing the same, wherein the FAS3420RH gear steel produced by the method satisfies the following end hardenability: j6 =38-43 HRC, j9=30-35 HRC, j15=25-30 HRC. The surface quality is good, the processing performance is good, the isothermal annealing banded structure is less than or equal to 2.5 level, the good processing performance and the service life of the material are ensured, and the number of continuous casting furnaces can reach 15 furnaces.
The invention aims at realizing the following steps:
the invention provides FAS3420RH gear steel, which comprises the following chemical components in percentage by mass: 0.19 to 0.24 percent of C, 0.20 to 0.35 percent of Si, 0.75 to 0.88 percent of Mn, less than or equal to 0.025 percent of P, 0.020 to 0.035 percent of S, 0.55 to 0.63 percent of Cr, 0.58 to 0.62 percent of Ni, 0.15 to 0.25 percent of Mo, and Cu: 0.08% or less, alt 0.010-0.045%, V0.02%, ti 0.02%, sn 0.05%, nb 0.02%, B0.0008%, O0.0015%, and Fe and unavoidable impurities in balance.
The gear steel of the invention has the main functions and design basis corresponding to each element in the chemical components:
c is the most basic element in steel and is also the most economical strengthening element. Among all elements, the carbon has the greatest capability of improving the strength of the steel, and the strengthening of the carbon on the quenched and tempered steel is about 9 times of chromium and 18 times of manganese, so that the carbon content of the steel is determined to be 0.19-0.24% in order to ensure that the gear has good toughness at the center after carburization and quenching and tempering.
Si can be used as a deoxidizing element and also is a basic solid solution strengthening element, hardenability is improved, meanwhile, si can cause oxidation in a cementite layer and influence the residual austenite amount during carburization of steel, and therefore the content of Si is determined to be 0.20-0.35%.
Mn has solid solution strengthening effect on steel and can strongly improve the hardenability of the steel, and the content range of Mn is determined to be 0.82-0.88%.
Cr has solid solution strengthening effect on steel, and improves the hardenability of the steel. The invention determines the range of Cr content to be 0.59-0.63%.
Ni strengthens ferrite and refines pearlite in steel, and the total effect is to improve strength without reducing plasticity and toughness of steel. The range of Ni content in the present invention is determined to be 0.58-0.62%.
Mo is carbide forming element, can improve the hardenability of steel, refine grains, improve toughness, improve carbide non-uniformity, and has stable carbide, and is difficult to transfer to solid solution at high temperature, thereby improving the heat resistance of steel. The heat treated alloy structural steel can reduce the tempering brittleness of the steel and improve the impact toughness. The present invention determines the Mo content to be 0.15-0.25%.
The addition of S can improve the cutting performance of the steel, but can generate hot brittleness of the steel and reduce the plasticity and toughness of the steel, so that the S content is determined to be 0.015-0.035%.
Al is added as deoxidizing element in steel, and forms fine aluminum nitride grains with fine dispersion with N to refine grains except for reducing dissolved oxygen in molten steel, but the Al content is too large, and Al is easy to form in the molten steel smelting process 2 O 3 Brittle inclusions are removed, and the purity of molten steel is reduced. The Al content of the present invention is determined to be 0.025 to 0.045%.
Based on the technical scheme, further, the FAS3420RH gear steel comprises the following chemical components in percentage by mass: 0.19 to 0.24 percent of C, 0.20 to 0.30 percent of Si, 0.80 to 0.88 percent of Mn, less than or equal to 0.025 percent of P, 0.020 to 0.035 percent of S, 0.58 to 0.63 percent of Cr, 0.58 to 0.62 percent of Ni, 0.15 to 0.25 percent of Mo, and Cu: 0.08% or less, alt 0.010-0.045%, V0.02%, ti 0.02%, sn 0.05%, nb 0.02%, B0.0008%, O0.0015%, and Fe and unavoidable impurities in balance.
The invention also provides a production method of the FAS3420RH gear steel, which comprises the following steps: smelting by an EBT electric furnace, LF refining, VD refining, continuous casting, heating, rolling and annealing.
Based on the technical scheme, further, the raw materials of the production method are high-quality molten iron and scrap steel, and the molten iron content is more than or equal to 60%.
Based on the technical scheme, further, the smelting process of the EBT electric furnace comprises the following steps: foam slag in the whole process, the temperature is 1640-1680 ℃, and C in molten steel is as follows: tapping when 0.05 to 0.10 percent and P is less than or equal to 0.013 percent, wherein steel and slag are required to be left in tapping, oxidizing slag is prevented from entering a ladle, and the tapping time of an electric furnace is 3 to 6 minutes.
Based on the technical scheme, 2.5-3.5 kg/t aluminum powder is added before tapping for pre-deoxidation, and ferroalloy and slag are added when tapping is carried out for 1/5-1/3.
Based on the technical scheme, further, the LF refining procedure: in the LF refining process, bottom argon blowing stirring is carried out in the whole process, active lime, coke powder carburant and fluorite are adopted for briquetting and slagging, after liquid slag is formed, alumina balls are added for diffusion deoxidation, the operation of white slag is maintained in the whole process, and the retention time of the white slag is more than or equal to 20min; the argon pressure is controlled to be 0.2-0.3 MPa in the whole process, so that secondary oxidation caused by the naked molten steel is prevented; the process of desulfurizing before adding sulfur is adopted, and sulfur is removed to less than or equal to 0.005% in the LF refining process.
Based on the technical scheme, further, the VD refining process comprises the following steps: feeding a Ca-Si wire before vacuum at the VD temperature of 1664-1679 ℃, starting timing when the vacuum degree reaches 100Pa, and keeping the time at 15min or more; finally deoxidizing after vacuum breaking, feeding an Al wire, feeding the S wire according to the S content in steel, and statically blowing argon after vacuum breaking, wherein the pressure is 0.1-0.3 MPa, and the time of statically blowing argon is more than or equal to 30min; after the static argon blowing is finished, a heat preservation agent is uniformly added to carbonize rice hulls, so that the uniform coverage of the rice hulls is ensured, and the tapping temperature is 1570-1600 ℃.
Based on the technical scheme, further, the continuous casting process comprises the following steps: argon protection pouring, wherein the stirring adopts a crystallizer (M-EMS) and a solidification end (F-EMS) to be combined and stirred, and the water flow of the crystallizer is 160-170M 3 And/h, the specific water quantity of the secondary cooling water is 0.2-0.40L/g, the pulling speed is 0.9m/min when the superheat degree is less than or equal to 25 ℃, and the pulling speed is 0.85m/min when the superheat degree is 25-30 ℃, so that steady casting is realized.
Based on the above technical scheme, further, the heating process: the preheating section 860+/-20 ℃, the heating section 1180+/-20 ℃, the soaking section 1190+/-20 ℃, the tapping temperature 1170-1190 ℃ and the total heating time not less than 180min.
Based on the technical scheme, further, the rolling process comprises the following steps: high-pressure water descaling before rolling, wherein the descaling pressure is 28-30 MPa, the two-roller reversible cogging mill with phi 1150mm and the pushing bed with a turning steel hook are used for 5-pass steel rolling, and the turning steel before 1-pass and 3-pass steel rolling is matched with descaling, and the rolling reduction is 38mm, 5mm, 49mm, 3mm and 2mm respectively; the initial rolling temperature is 1100-1200 ℃, the final rolling temperature is 850-1000 ℃, the steel is immediately put into a pit for heat preservation or stacked cooling after being put into a cooling bed, the steel with the specification of phi 85mm or more is preserved, the pit-out temperature is 300 ℃ or less, and the heat preservation time is 24 hours or more; steel products with the specification of less than phi 85mm are cooled in a stacking way.
Based on the above technical scheme, further, the annealing process: heating at 920-940 deg.c, maintaining for 25-35 min, air cooling for 2-5 min, isothermal cooling at 670-690 deg.c for 80-100 min, and air cooling.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides FAS3420RH gear steel and a production method thereof, the sulfur content of the produced FAS3420RH gear steel is 0.020-0.035%, the number of continuous casting furnaces can reach 15 furnaces, and the hardenability of steel ends meets the following conditions: j6 =38-43 HRC, j9=30-35 HRC, j15=25-30 HRC; the isothermal annealing band structure is less than or equal to 2.5 grades. The surface quality is good.
2. The scale on the surface of the Ni-containing steel is difficult to remove after heating, is adhered to the surface of a steel billet, has poor surface quality after rolling, and is easy to form pit defects.
Drawings
In order to more clearly illustrate the embodiments of the present invention, the drawings to which the embodiments relate will be briefly described.
FIG. 1 is a graph of an isothermal annealing process for a strip tissue sample;
FIG. 2 is a rolled strip-like structure of example 1 at level 1.0;
FIG. 3 is a 1.0 grade isothermal annealed strip of example 1.
Detailed Description
The following detailed description of the invention is provided in connection with examples, but the implementation of the invention is not limited thereto, and it is obvious that the examples described below are only some examples of the invention, and that it is within the scope of protection of the invention to those skilled in the art to obtain other similar examples without inventive faculty.
Examples 1 to 5
Examples 1-5 provide a production method of FAS3420RH gear steel, and the main chemical compositions and mass percentage contents of the FAS3420RH gear steel are shown in table 1; the method comprises the following steps:
smelting by an EBT electric furnace: the waste steel 17t (active lime is filled on the bottom of the furnace before the charging to lighten the impact on the bottom of the furnace, a molten pool is formed in advance, electric arc is stabilized and dephosphorization is carried out early), molten iron is added after 20 minutes of power transmission, the temperature of the molten iron ranges from 1250 ℃ to 1350 ℃, the weight of the molten iron ranges from 35.8t, oxygen is oxidized and boiled vigorously, the oxidizing temperature is 1680 ℃, high alkalinity, large slag quantity and low-temperature slag are formed in the early stage of oxidation to strengthen dephosphorization effect, when the furnace burden is melted by more than 70%, an electric furnace foaming agent is blown into the slag, and after the steel is melted, the steel is sampled and analyzed for C, mn, P, S and residual elements. C is 0.05 percent, P is 0.010 percent, and the tapping temperature is 1680 ℃ during tapping; 3kg/t aluminum powder is added before tapping to carry out pre-deoxidation. Iron alloy (121 kg of aluminum iron, 301kg of medium manganese and 202kg of low chromium) and slag (400 kg of lime and 100kg of alumina powder) are added when the electric furnace is tapped for 1/4 of the time, the tapping needs to pay attention to steel and slag, the oxidizing slag is prevented from entering a ladle, and the tapping time of the electric furnace is 3-6 min.
Refining in an LF furnace: firstly, switching on argon gas to blow off a slag surface for measuring temperature when the steel ladle is in a receiving position, taking a primary sample for analyzing all components, and carrying out coarse adjustment on the components according to the analysis result and the lower limit of the requirement; in the LF refining process, the whole process is subjected to bottom argon blowing stirring, 500kg of active lime, 10kg of coke powder carburant, 50kg of fluorite briquetting for slagging, 200kg of alumina balls are added for diffusion deoxidation after liquid slag is formed, slag white is obtained, and the temperature meets the requirement for secondary sample analysis of the whole components; continuously regulating slag by using a diffusion deoxidizer after taking out the secondary sample, keeping proper slag alkalinity and good fluidity, keeping white slag operation in the whole process, reporting back the secondary sample result, and carrying out component fine adjustment according to target control components, wherein the white slag keeping time is more than or equal to 20min; the argon pressure is controlled to be 0.2-0.3 MPa in the whole process, so that secondary oxidation caused by the naked molten steel is prevented; the temperature of the ladle is 1679 ℃, and sulfur is removed to be less than or equal to 0.005% in the LF refining process.
And (3) VD refining: the VD temperature is 1664 ℃, ca-Si wire is fed for 120m before vacuum, and the argon pressure is controlled to be 0.1-0.3 MPa before the vacuum pump is started, so that the slag surface micro-motion molten steel is not exposed; starting timing when the vacuum degree reaches 100Pa, and keeping for 15min; and finally deoxidizing after vacuum breaking, feeding Al wires, and feeding S wires according to the S content in the steel and the middle and upper limits of the specification. And after vacuum breaking, argon is statically blown, wherein the pressure is 0.1-0.3 MPa, and the time of static argon blowing is more than 30min. After the static argon blowing is finished, 80 kg/furnace of carbonized rice husk serving as a heat preservation agent is uniformly added, the heat preservation agent is added when the liquid level of steel still fluctuates at the end of the static argon blowing of each furnace, the uniform coverage is ensured, and the ladle hanging temperature is 1583 ℃.
Continuous casting: in the continuous casting, a billet is cast by a 3-machine 3-flow arc continuous casting machine, a 235 multiplied by 265mm continuous casting blank is cast under the protection of argon at the temperature of 1578 ℃ in a continuous casting ladle; baking the middle ladle for 4 hours; the stirring adopts the combined stirring of a crystallizer (M-EMS) and a solidification end (F-EMS), the electric stirring current is 360A, the pulling speed is 0.85M/min, the superheat degree is 26 ℃, and the water flow of the crystallizer is 160M 3 And/h, the specific water quantity of the secondary cooling water is 0.30L/g, so that steady casting is realized.
Heating: in the heating stage, the preheating section 860+/-20 ℃, the heating section 1180+/-20 ℃, the soaking section 1190+/-20 ℃, the tapping temperature 1170-1190 ℃ and the total heating time of 360min.
Rolling: in the rolling stage, high-pressure water is used for descaling before rolling, the descaling pressure is 28-30 MPa, the phi 1150mm two-roller reversible cogging mill and the pushing bed with the turning steel hook are used for 5-pass steel rolling, the steel is turned before 1-pass and 3-pass steel turning, and the descaling is matched, and the rolling reduction is 38mm, 5mm, 49mm, 3mm and 2mm respectively. The initial rolling temperature is 1150 ℃, the final rolling temperature is 910 ℃, the rolling specification phi is 85mm, the steel is put into a pit for heat preservation immediately after being put into a cooling bed, the pit outlet temperature is less than or equal to 300 ℃, and the heat preservation time is more than or equal to 24 hours.
Annealing: the isothermal annealing process of the strip-shaped tissue sample comprises the following steps: heating at 930 ℃, preserving heat for 30min, air-cooling for 3min, isothermal for 90min at 680 ℃, and air-cooling.
The steels prepared in the five examples were tested for physical properties and the results are shown in Table 2.
TABLE 1 major chemical Components and mass fractions of FAS3420RH Gear Steel in examples 1-5
TABLE 2 physical Properties of FAS3420RH Gear Steel in example 1
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims (10)

1. The FAS3420RH gear steel is characterized by comprising the following chemical components in percentage by mass: 0.19 to 0.24 percent of C, 0.20 to 0.35 percent of Si, 0.75 to 0.88 percent of Mn, less than or equal to 0.025 percent of P, 0.020 to 0.035 percent of S, 0.55 to 0.63 percent of Cr, 0.58 to 0.62 percent of Ni, 0.15 to 0.25 percent of Mo, and Cu: 0.08% or less, alt 0.010-0.045%, V0.02%, ti 0.02%, sn 0.05%, nb 0.02%, B0.0008%, O0.0015%, and Fe and unavoidable impurities in balance.
2. The production method of FAS3420RH gear steel according to claim 1, wherein the process flow of the production method comprises: smelting by an EBT electric furnace, LF refining, VD refining, continuous casting, heating, rolling and isothermal annealing of a strip-shaped tissue sample.
3. The method according to claim 2, wherein the strip-like tissue sample annealing step: heating at 920-940 deg.c, maintaining for 25-35 min, air cooling for 2-5 min, isothermal cooling at 670-690 deg.c for 80-100 min, and air cooling.
4. The production method according to claim 2, wherein the raw materials of the production method are molten iron and scrap steel, and the molten iron content is more than or equal to 60%.
5. The production method according to claim 2, wherein the EBT electric furnace smelting process: foam slag in the whole process, the temperature is 1640-1680 ℃, and C in molten steel is as follows: tapping when 0.05 to 0.10 percent and P is less than or equal to 0.013 percent, wherein steel and slag are required to be left in tapping, and the tapping time of an electric furnace is 3 to 6 minutes.
6. The production method according to claim 2, wherein the LF refining process: in the LF refining process, bottom argon blowing stirring is carried out in the whole process, the operation of white slag is kept in the whole process, and the white slag keeping time is more than or equal to 20min; the argon pressure is controlled to be 0.2-0.3 MPa in the whole process; the process of desulfurizing before adding sulfur is adopted, and sulfur is removed to less than or equal to 0.005% in the LF refining process.
7. The production method according to claim 2, wherein the VD refining process: when the vacuum degree reaches 100Pa, starting timing, and keeping the time for more than or equal to 15min; finally deoxidizing after vacuum breaking, feeding an Al wire, feeding the S wire according to the S content in steel, and statically blowing argon after vacuum breaking, wherein the pressure is 0.1-0.3 MPa, and the time of statically blowing argon is more than or equal to 30min; the tapping temperature is 1570-1600 ℃.
8. The production method according to claim 2, wherein the continuous casting process: argon protection pouring, stirring adopts a crystallizer and a solidification end to jointly stir, and the water flow of the crystallizer is 160-170m 3 And/h, the specific water quantity of the secondary cooling water is 0.2-0.40L/g, the pulling speed is 0.9m/min when the superheat degree is less than or equal to 25 ℃, and the pulling speed is 0.85m/min when the superheat degree is 25-30 ℃.
9. The method according to claim 2, wherein the heating step: the preheating section 860+/-20 ℃, the heating section 1180+/-20 ℃, the soaking section 1190+/-20 ℃, the tapping temperature 1170-1190 ℃ and the total heating time not less than 180min.
10. The method according to claim 2, wherein the rolling process comprises: in the rolling stage, high-pressure water descaling is carried out before rolling, the descaling pressure is 28-30 MPa, a phi 1150mm two-roller reversible cogging mill and a pushing bed with a turning steel hook are adopted, 5-pass steel rolling is carried out, 1-pass turning steel is carried out before 3-pass steel turning, and descaling is matched; the initial rolling temperature is 1150 ℃, the final rolling temperature is 910 ℃,
the rolling specification is more than or equal to phi 85mm, the steel is immediately put into a pit for heat preservation after being put into a cooling bed, the pit outlet temperature is less than or equal to 300 ℃, and the heat preservation time is more than or equal to 24 hours;
steel products with the specification of less than phi 85mm are cooled in a stacking way.
CN202310735001.XA 2023-06-20 2023-06-20 FAS3420RH gear steel and production method thereof Pending CN116694996A (en)

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