CN109082592B - Corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance and production process thereof - Google Patents

Corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance and production process thereof Download PDF

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CN109082592B
CN109082592B CN201810981390.3A CN201810981390A CN109082592B CN 109082592 B CN109082592 B CN 109082592B CN 201810981390 A CN201810981390 A CN 201810981390A CN 109082592 B CN109082592 B CN 109082592B
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陈红卫
刘泳
赵江
李绍杰
郭子强
刘毅
郝志超
张立良
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HBIS Co Ltd
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    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
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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
    • 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
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    • 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
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    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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    • 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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Abstract

The invention discloses a corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance and a production process thereof, wherein the hot-rolled wire rod comprises the following chemical components in percentage by mass: c: 0.40-0.70%, Si: 1.4-1.9%, Mn: 0.5-0.8%, P is less than or equal to 0.025%, S: 0.002-0.020%, Cr: 0.80-1.50%, Ni: 0.20 to 0.50%, Cu: 0.20 to 0.50%, Nb: 0.004-0.020%, Al: 0.003-0.010% of Fe and inevitable impurities in balance; the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rolling. The corrosion-resistant spring steel hot-rolled wire rod is made into the elastic strip through the heat treatment of customers, the corrosion resistance, particularly the pitting voltage of the elastic strip is improved by more than 0.185V, and the elastic strip has certain popularization value.

Description

Corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance and production process thereof
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance and a production process thereof.
Background
With the approach of 2025 manufacturing step in China, the mechanical industry in China is developed at a high speed, and the use amount of high-temperature springs, disc springs and wave springs is larger and larger. The service environment of the springs is complex and may be influenced by alternating impact, high temperature, chemical corrosion and the like. The potential difference formed by segregation and inclusion in the spring steel can cause electrochemical corrosion, because the metallographic structure of the spring steel is F + P at room temperature, sulfur-phosphorus impurities and non-metallic inclusions in the steel, cementite and impurities in pearlite and the electronic potential of inclusions are higher than that of iron, microcell reaction can occur in conductive humid air, the iron loses electrons, the impurities obtain electrons, and electron transfer phenomenon occurs, if the environmental temperature is high, the electrochemical reaction is accelerated, so that the service life of the spring is greatly shortened, and the spring fails in early stage. Since the spring has very high requirements for fatigue life and reliability, the quality requirements for inclusion, segregation, and the like of the spring steel wire rod are also very strict.
Most domestic iron and steel enterprises adopt the process flow as follows: the aluminum (a small amount) deoxidation, LF + VD (RH) degassing, continuous casting and hot rolling are carried out on the steel discharged from a converter (an electric furnace), namely the aluminum is strongly deoxidized, and CaO-Al is adopted for refining synthetic slag2O3Controlling the slag system to be high-alkalinity and low-oxidability, and feeding SiCa wire to Al2O3And (3) performing denaturation treatment on the impurities, floating and discharging formed large-particle impurities, and leaving the large-particle impurities in the steel as fine and dispersed spherical impurities. However, due to unreasonable other process factors (refining time, argon blowing system and the like), even if the oxygen content is controlled, the brittle and non-deformable impurities cannot be sufficiently deformed or float upwards and are retained in the molten steel. Deoxidation with silicon/manganese is another smelting process but also has disadvantages.
An aluminum-free deoxidation process is adopted, and for example, an invention patent (grant CN 105907919A; application publication No. 2016.08.31) discloses a refining process adopting aluminum-free deoxidation and low-alkalinity slag. The process flow comprises the following steps: electric furnace-LF-VD-continuous casting. However, the electric arc furnace steelmaking process is adopted in the patent, the residual elements of molten steel are high, and the white slag time is insufficient due to the double-slag operation (high-alkalinity slag in the early stage and alkalinity reduction in the later stage) in the LF refining period; the molten steel is easy to be slag-rolled due to improper VD vacuum refining operation; the continuous casting adopts a small square billet rolled wire with the thickness of 150mm by 150mm, and the center segregation is not easy to control.
A method for controlling nonmetallic inclusions by using a low-alkalinity slag system, for example, Chinese invention patent (publication No. CN040567871B, published by No. 2016.03.09) discloses a spring steel wire production process for controlling inclusions, wherein the inclusions in steel in the low-alkalinity slag system are denatured into low-melting-point silicate inclusions, but the process easily causes the silicate inclusions to exceed the standard, and the patent does not relate to the whole process flow from raw material molten iron to wires.
A method for controlling nonmetallic inclusions by using a high-alkalinity slag system is disclosed in the patent of invention (publication No. CN102162068B1, publication No. 2013.07.31), for example, a spring steel and a manufacturing and heat treatment method thereof, wherein the production process comprises the following steps: electric furnace-LF-VD-continuous casting-rolling-heat treatment. The alkalinity of refining slag in LF is controlled to be 2.5-3.0, the required strength can be obtained through a heat treatment process, however, the B-type inclusion in steel is difficult to remove easily due to a high-alkalinity refining slag system with the alkalinity of 2.5-3.0, and the fatigue performance of spring steel is affected.
A BOF + LF + VD + CC process route is adopted, and for example, the invention patent (application publication No. CN 106947921A, application publication No. 2017.07.14) discloses corrosion-resistant spring steel for high-speed railway elastic bars and a production method thereof. C: 0.50-0.60%, Si: 1.4-2.2%, Mn: 0.7-1.0%, P: 0.015-0.030%, S is less than or equal to 0.015%, Cr: 0.36-0.5%, Ni: 0.36-0.60%, Cu: 0.26-0.50%, and the balance of Fe and inevitable impurities. The invention adopts the conventional process, adopts one-step heating to form the material and produce the straight long material, and improves the corrosion resistance of the steel body by reasonably adjusting elements.
Aiming at the technical problems of producing the corrosion-resistant spring steel wire rod by aluminum and silicomanganese deoxidation and low-alkalinity slag system smelting and rolling, the corrosion resistance of the wire rod is further improved on the premise that the composition design meets the performance of the spring steel, and the production process which belongs to the process for producing clean steel by aluminum-free deoxidation and obtains the whole process flow with excellent wire rod internal quality and surface decarburization has important economic benefits and social benefits.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance; meanwhile, the invention also provides a production process of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance. Aiming at the technical problems of aluminum and silicomanganese deoxidation and low-alkalinity slag system smelting and rolling production of corrosion-resistant spring steel wire rods, the invention provides a process for producing clean steel by aluminum-free deoxidation in order to further improve the self corrosion resistance on the premise that the composition design meets the performance of the spring steel; the gas content and the size and the property of generated impurities are comprehensively considered, the continuous casting large rectangular billet adopts the process route of cogging and rolling to form a material by primary rolling, the segregation grade of the center of a disc is improved, the cogging of the primary rolling billet and the rolling of a wire rod adopt unique heating modes, and the production process of the whole process flow with excellent wire rod internal quality and surface decarburization is obtained by the primary rolling billet polishing and controlled cooling process control.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: the corrosion-resistant hot-rolled spring steel wire rod with good comprehensive performance comprises the following chemical components in percentage by mass: c: 0.40-0.70%, Si: 1.4-1.9%, Mn: 0.5-0.8%, P is less than or equal to 0.025%, S: 0.002-0.020%, Cr: 0.80-1.50%, Ni: 0.20 to 0.50%, Cu: 0.20 to 0.50%, Nb: 0.004-0.020%, Al: 0.003-0.010% and the balance of Fe and inevitable impurities.
The spring steel hot-rolled wire rod has the performance that the tensile strength is more than or equal to 1779 MPa, the yield strength is more than or equal to 1591MPa, the reduction of area is more than or equal to 36 percent, and the elongation after fracture is more than or equal to 6.5 percent.
The pitting voltage of the spring steel hot-rolled wire rod is more than or equal to-0.501V, and the corrosion weight loss is less than or equal to 0.552 g.
The invention also provides a production process of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance, which comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling; in the cogging and blooming process, cogging and rolling a 280mm × 380mm rectangular billet into a 150mm × 150mm square billet, wherein the heating time is 4-5 h, the temperature of a heating section is 1120-1250 ℃, and the temperature of a soaking section is 1120-1260 ℃; in the wire rolling process, the temperature of a heating section is 900-1100 ℃, the temperature of a soaking section is 1050-1100 ℃, the finish rolling temperature is controlled to be 870-910 ℃ in the wire rolling process, and the spinning temperature is controlled to be 810-830 ℃.
In the smelting process, the proportion of smelting raw material scrap steel (GB 4223 scrap steel and iron) in the raw materials of the smelting furnace is controlled to be 15-20%, and molten iron is pretreated before smelting and is desulfurized to S: 0.015-0.030%; smelting by adopting a combined blowing converter, wherein the steelmaking end point C is more than or equal to 0.08 percent, discharging slag by adopting double-blocking and tight control of an infrared sliding plate and a slag-stopping cone during tapping, precipitating and deoxidizing by adopting 15-25 kg/t of steel ferrosilicon, and adding 2.5-3.5 kg/t of steel synthetic refining slag along the steel flow during tapping 1/2.
In the LF refining process, aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 4.0-6.0 kg/t steel and silicon carbide 0.5-1.5 kg/t steel are added for diffusion deoxidation, fluorite 0-2.5 kg/t steel (the dosage is adjusted according to the slag thickness) and wollastonite 2.5-3.5 kg/t steel are added for slagging, and the final slag alkalinity is as follows: 1.5 to 2.0, Al2O3Less than 10.0 percent, the carburant is used for carburant, the white slag keeping time is more than or equal to 20min, and the power transmission time is more than or equal to 30 min.
According to the RH vacuum treatment process, the degree of vacuum of RH vacuum treatment is less than or equal to 30Pa, the vacuum maintaining time is 10-15 min, argon is blown during vacuum treatment to ensure that the liquid level of molten steel is not exposed, the soft blowing time is more than or equal to 15min, then an argon flow valve is closed, and the RH vacuum treatment process is fully kept still until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts 0.5-1.0 kg/t steel special ferrosilicon.
In the continuous casting process, a 280mm multiplied by 380mm rectangular blank is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high carbon steel mode is adopted under the tail end soft reduction; and (3) carrying out argon protection in the whole process, detecting slag in a ladle, controlling the superheat degree to be 15-30 ℃ and the target superheat degree: the delta T =20 ℃, the drawing speed is controlled to be 0.60-0.70 m/min, and the target drawing speed is: 0.65 m/min.
In the grinding process, a grinder is used for grinding a primary rolling blank of 150mm multiplied by 150mm, the grinding amount of a single side is 1.0-2.0 mm, a decarburized layer and surface defects are removed, corners of the ground primary rolling blank are chamfered, the chamfer angle is 35-55 degrees, and the chamfer angle width is more than or equal to 5 mm.
According to the wire rolling process, a 150mm square billet is fed into a furnace, steel is loaded in a blank step by step, the heating time is controlled to be 1.0-1.5 h, the residual oxygen in the furnace is less than or equal to 1.5%, the roller speed is controlled to adopt an inlet speed of 24m/s, and the roller speed is gradually increased step by step and the amplitude is increased by 1.8 m/s.
The design idea of the chemical components of the invention is as follows:
the content of C is controlled to be C: 0.40-0.70%, and by reducing the carbon content, the corrosion resistance of the steel is improved while the strength of the spring is met, and the adverse effect of later-stage corrosion rate of the spring workpiece in use is improved to a certain extent. The content of C is preferably 0.51-0.60%.
The content of Si is controlled to be Si: 1.4-1.9%, and Si is one of the main elements of spring steel for improving the elasticity and reducing force. The method plays a main role in qualified residual deformation of the spring. Too high a content promotes precipitation of graphitic carbon in the steel. The excessively low content of the carbon-based composite material improves the elasticity reducing force and the solid solution strengthening effect is not obvious. The corrosion resistance of the steel can be improved by combining with certain elements of Cu, P and Cr. The invention preferably selects 1.45-1.65% of silicon.
The Mn content is controlled to be 0.5-0.8%, certain hardenability of steel is kept, but considering that the influence of the addition amount of Cr of the steel on the structure is large when the steel is cooled, the Mn is too high and is easy to generate positive segregation, and reports of Mn elements on the improvement of corrosion resistance are less, the Mn: 0.5 to 0.6 percent.
The content of Cr is controlled to be 0.80-1.50%, Cr is an element capable of improving hardenability, and meanwhile, Cr can form a compact oxide film on the surface of steel, so that the passivation capability of the steel is improved. The effect of adding Cr and Cu at the same time is better, but the elasticity reducing resistance of the steel is reduced by excessively high Cr. The invention preferably selects Cr: 0.90 to 1.0 percent.
The content of Nb is controlled to be 0.004-0.02%, Nb element exists in the form of carbon and nitride in steel, and tiny carbon and nitride can pin grain boundaries and refine grains. Nb can improve the high-temperature strength of the steel and improve the corrosion resistance of the grain boundary. The content of Nb is preferably controlled to be 0.01-0.02%.
The content of Cu is controlled to be 0.20-0.50%, Cu is the most effective alloy element for improving the corrosion resistance of steel, and the harmful effect of sulfur can be reduced. In addition, the enrichment of Cu and other alloy elements on the inner surface of the rust layer (namely in the inner rust layer close to the substrate) increases the compactness and the protection of the rust layer, thereby improving the atmospheric corrosion resistance. However, too high a Cu content causes concentration and segregation at grain boundaries, causing hot embrittlement. The Cu content of the invention is preferably Cu: 0.20 to 0.30 percent.
The Al content is controlled to be 0.003-0.010%, and the Al can refine grains and improve the strength of the steel, but in the scheme, the Al content is preferably 0.003-0.008% in the invention from the viewpoint of controlling the source of oxide inclusions as much as possible in silicon deoxidation.
The P content is controlled to be less than or equal to 0.030 percent, and phosphorus can accelerate the uniform dissolution of steel and Fe2+The oxidation speed of the steel is beneficial to forming a uniform FeOOH rust layer on the surface of the steel, and a compact oxide layer can be formed with elements such as Cr, Cu and the like. However, the phosphorus increases the cold brittleness of the steel, the content cannot be too high, and the scheme is preferably that the ratio of P: 0.010-0.025%.
The Ni content is controlled to be 0.20-0.50%, the Cu-P-Ni-Cr series elements can improve the corrosion resistance of steel and reduce the cost of the steel, and the Ni content is preferably Ni: 0.20 to 0.30 percent.
The production process design idea of the invention is as follows:
the steel-making process comprises the following steps: the method comprises the steps of desulfurizing to a target position by molten iron pretreatment, forming a good foundation for low-alkalinity refining slag desulfurization, deoxidizing by adopting ferrosilicon, adding active lime and silicon carbide into a refining slag system for diffusion deoxidation, adding fluorite and wollastonite for slagging, keeping a medium alkalinity range (R = 1.5-2.0) in refining final slag, and controlling Al from the source2O3And (4) generating the inclusions. The special carburant and special ferrosilicon are adopted to control the contents of nitrogen and titanium in steel and Ds-type inclusions in molten steel.
The continuous casting process comprises the following steps: the whole process of argon protection atmosphere prevents the secondary oxidation of the molten steel in the continuous casting process, adopts ladle slag discharge detection and special covering slag to prevent the molten steel from secondary pollution and good heat preservation and adsorption inclusion effects, adopts a large-square-blank crystallizer for stirring and soft reduction, and performs a rolling process of forming a material by two fires, thereby effectively controlling the center carbon segregation of the wire rod and finally obtaining the spring steel wire rod with good performance. The rolling process comprises the following steps:
the cogging process adopts high-temperature long-time heating, and has the characteristic that oxide skin of nickel-containing steel is not easy to fall off, after the surface of the primary rolling billet is polished, the heating time and the rolling rhythm of wire rolling are strictly controlled by adopting a blank loading mode; the temperature and the heating atmosphere in the furnace are effectively controlled by utilizing the thermocouple of the heating furnace and the residual oxygen meter, and the control of the depth of the spring steel decarburization layer is ensured. In the rolling process, the structure and the performance of a finished product are ensured by optimizing the control of the rolling speed and the rolling temperature.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: 1. the invention controls the generation of B inclusion from the source by pretreating and desulfurizing molten iron, deoxidizing by adopting ferrosilicon, adding active lime and silicon carbide to a refining slag system for diffusion deoxidizing and adding fluorite and wollastonite for slagging. 2. The invention adopts special ferrosilicon to control the titanium source in the steel, thereby controlling Ds type inclusions in the molten steel. 3. The argon protection atmosphere in the whole continuous casting process prevents the molten steel from being secondarily oxidized in the continuous casting process, adopts ladle slag discharge detection and covering slag to prevent the molten steel from secondary pollution and good heat preservation and adsorption inclusion effects, adopts a large rectangular billet crystallizer for stirring and soft reduction, and performs a rolling process of forming a material by two fires, thereby effectively controlling the center carbon segregation of the wire rod and obtaining the spring steel wire rod with good performance. 4. In the rolling process, the structure and the performance of a finished product are ensured by optimizing the control of the rolling speed and the rolling temperature. 5. The corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance is made into the elastic strip after being subjected to heat treatment by customers, the corrosion resistance, particularly the pitting voltage of the elastic strip is improved by more than 0.185V, and the elastic strip has certain popularization value.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Example 1
The chemical components and the mass percentage content of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance are shown in table 1, the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling, and the specific process steps are as follows:
(1) smelting: controlling the ratio of smelting raw material scrap steel to be 16%, and desulfurizing molten iron after pretreatment before smelting until S: 0.298%; smelting by adopting a combined blown converter, wherein the steel-making end point C is as follows: 0.10 percent, adopting an infrared slide plate and a slag stopping cone to strictly control slag discharging during tapping, adopting 17.3kg/t steel ferrosilicon to precipitate and deoxidize, and adding 2.81kg/t steel synthetic refining slag along the steel flow during tapping 1/2;
(2) an LF refining procedure: aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 4.9kg/t steel and silicon carbide 0.8kg/t steel are added for diffusion deoxidation, fluorite 0.5kg/t steel and wollastonite 3.2kg/t steel are added for slagging, and the final slag alkalinity is as follows: 1.87, Al2O3: 8.5 percent, recarburizing by using a recarburizing agent, keeping white slag for 22min, and transmitting electricity for 32 min;
(3) RH vacuum treatment process: in the RH vacuum treatment process, the vacuum degree is 25Pa, the vacuum maintaining time is 12min, argon is blown during the vacuum treatment, the argon flow is controlled to regulate the flow according to the fluctuation condition of the liquid level, the liquid level of the molten steel is ensured not to be exposed, the soft blowing time is 17min, then an argon flow valve is closed, and the molten steel is fully kept stand until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts 0.6kg/t steel special ferrosilicon;
(4) and (3) continuous casting process: a rectangular blank of 280mm multiplied by 380mm is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high-carbon steel mode is adopted under the tail end soft reduction; argon protection is carried out in the whole process, ladle slag tapping detection is carried out, the superheat degree is controlled to be 23 ℃, and the pulling speed is controlled to be 0.65 m/min;
(5) cogging and blooming: cogging and rolling the 280mm × 380mm rectangular billet into a 150mm × 150mm square billet, wherein the heating time is 4.6h, the temperature of a heating section is 1125 ℃, and the temperature of a soaking section is 1135 ℃;
(6) grinding process, namely grinding the primary rolling blank of 150mm × 150mm by using a grinding machine, wherein the grinding amount of one side is 1.2mm, removing decarburized layers and surface defects, and chamfering the corners of the ground primary rolling blank to form chamfered corners of 37 chamfered corners0The width of the chamfered inclined plane is 6 mm;
(7) a wire rod rolling procedure: the 150mm x 150mm square billet is put into a furnace, steel is loaded in a blank step by step, the heating time is controlled to be 1.2h, the temperature of a heating section is 920 ℃, the temperature of a soaking section is 1070 ℃, the residual oxygen in the furnace is 1.2 percent, the finish rolling temperature is controlled to be 880 ℃, the spinning temperature is controlled to be 815 ℃ in the wire rod rolling process, the inlet speed is 24m/s, the step-by-step increasing is carried out later, and the increasing amplitude is 1.8 m/s.
The purity index, the center segregation index, the mechanical property index, the corrosion resistance and the performance after being made into the elastic strip are shown in the table 2, the center segregation index, the mechanical property index and the corrosion resistance respectively in the table 3, the table 4 and the table 5.
Example 2
The chemical components and the mass percentage content of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance are shown in table 1, the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling, and the specific process steps are as follows:
(1) smelting: controlling the ratio of smelting raw material scrap steel to be 17%, and desulfurizing molten iron after pretreatment before smelting until S: 0.026%; smelting by adopting a combined blown converter, wherein the steel-making end point C is as follows: 0.09 percent, adopting an infrared slide plate and a slag stopping cone to strictly control slag discharging during tapping, adopting 18.1kg/t steel ferrosilicon to precipitate and deoxidize, and adding 2.75kg/t steel synthetic refining slag along the steel flow during tapping 1/2;
(2) an LF refining procedure: aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 5.1kg/t steel and silicon carbide 0.9kg/t steel are added for diffusion deoxidation, fluorite 0.4kg/t steel and wollastonite 3.5kg/t steel are added for slagging, and the final slag alkalinity is as follows: 1.73 of Al2O3: 9.3 percent, recarburizing by using a recarburizing agent, keeping white slag for 27min, and transmitting electricity for 35 min;
(3) RH vacuum treatment process: in the RH vacuum treatment process, the vacuum degree is 27Pa, the vacuum maintaining time is 14min, argon is blown during the vacuum treatment, the argon flow is controlled to regulate the flow according to the fluctuation condition of the liquid level, the liquid level of the molten steel is not exposed, the soft blowing time is 18min, then an argon flow valve is closed, and the molten steel is fully kept stand until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts 0.8kg/t steel special ferrosilicon;
(4) and (3) continuous casting process: a rectangular blank of 280mm multiplied by 380mm is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high-carbon steel mode is adopted under the tail end soft reduction; argon protection is carried out in the whole process, ladle slag tapping detection is carried out, the superheat degree is controlled to be 30 ℃, and the pulling speed is controlled to be 0.65 m/min;
(5) cogging and blooming: cogging and rolling the 280mm × 380mm rectangular billet into 150mm × 150mm square billet, wherein the heating time is 4.5h, the temperature of a heating section is 1130 ℃, and the temperature of a soaking section is 1140 ℃;
(6) grinding (including grinding 150mm × 150mm bloom with single side grinding amount of 1.4 mm) by grinding machine to remove decarburized layer and surface defect, and chamfering corners of the ground bloom to chamfer the chamfered corner angle of 40%0The width of the chamfered inclined plane is 7 mm;
(7) a wire rod rolling procedure: the 150mm x 150mm square billet is put into a furnace, steel is loaded in a blank step, the heating time is controlled to be 1.3h, the temperature of a heating section is 950 ℃, the temperature of a soaking section is 1055 ℃, the residual oxygen in the furnace is 1.1%, the finish rolling temperature is controlled to be 875 ℃, the spinning temperature is controlled to be 820 ℃ in the wire rod rolling process, the inlet speed is 24m/s, the later step-by-step increasing is carried out, and the amplitude is increased by 1.8 m/s.
The purity index, the center segregation index, the mechanical property index, the corrosion resistance and the performance after being made into the elastic strip are shown in the table 2, the center segregation index, the mechanical property index and the corrosion resistance respectively in the table 3, the table 4 and the table 5.
Example 3
The chemical components and the mass percentage content of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance are shown in table 1, the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling, and the specific process steps are as follows:
(1) smelting: controlling the ratio of smelting raw material scrap steel to be 18%, and desulfurizing molten iron after pretreatment before smelting until S: 0.0256%; smelting by adopting a combined blown converter, wherein the steel-making end point C is as follows: 0.13 percent, adopting an infrared slide plate and a slag blocking cone to carry out double-blocking and tight slag discharging during tapping, adopting 18.0kg/t ferrosilicon to carry out precipitation and deoxidation, and adding 2.91kg/t steel synthetic refining slag along the steel flow during tapping 1/2;
(2) an LF refining procedure: adopts aluminum-free deoxidation and bottom blowing argon in the whole LF refining process, and adds 5.1kg/t steel of active lime and 0.75 kg of silicon carbideAnd (2) carrying out diffusion deoxidation on kg/t steel, adding 0.4kg/t fluorite steel and 3.5kg/t wollastonite steel for slagging, wherein the final slag alkalinity is as follows: 1.68 of Al2O3: 7.8 percent, recarburizing by using a recarburizing agent, keeping white slag for 30min, and transmitting electricity for 34 min;
(3) RH vacuum treatment process: in the RH vacuum treatment process, the vacuum degree is 22Pa, the vacuum maintaining time is 13min, argon is blown during the vacuum treatment, the argon flow is controlled to regulate the flow according to the fluctuation condition of the liquid level, the liquid level of the molten steel is ensured not to be exposed, the soft blowing time is 20min, then an argon flow valve is closed, and the molten steel is fully kept stand until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts 0.7kg/t steel special ferrosilicon;
(4) and (3) continuous casting process: a rectangular blank of 280mm multiplied by 380mm is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high-carbon steel mode is adopted under the tail end soft reduction; argon protection is carried out in the whole process, ladle slag tapping detection is carried out, the superheat degree is controlled to be 20 ℃, and the pulling speed is controlled to be 0.65 m/min;
(5) cogging and blooming: cogging and rolling the 280mm × 380mm rectangular billet into 150mm × 150mm square billet, wherein the heating time is 4.3h, the temperature of a heating section is 1140 ℃, and the temperature of a soaking section is 1135 ℃;
(6) grinding (including grinding 150mm × 150mm bloom with single side grinding amount of 1.6 mm) by grinding machine to remove decarburized layer and surface defect, and chamfering the corners of the ground bloom to obtain chamfered angle of 45%0The width of the chamfered inclined plane is 8 mm;
(7) a wire rod rolling procedure: the method comprises the steps of putting a square billet with the diameter of 150mm multiplied by 150mm into a furnace, loading steel in an idle step, controlling the heating time to be 1.3h, the temperature of a heating section to be 980 ℃, the temperature of a soaking section to be 1070 ℃, the residual oxygen content in the furnace to be 1.0%, controlling the finish rolling temperature to be 890 ℃, controlling the spinning temperature to be 820 ℃ in the high-speed wire rod rolling process, adopting the inlet speed to be 24m/s, and then gradually increasing the speed by steps and increasing the amplitude by 1.8 m/s.
The purity index, the center segregation index, the mechanical property index, the corrosion resistance and the performance after being made into the elastic strip are shown in the table 2, the center segregation index, the mechanical property index and the corrosion resistance respectively in the table 3, the table 4 and the table 5.
Example 4
The chemical components and the mass percentage content of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance are shown in table 1, the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling, and the specific process steps are as follows:
(1) smelting: controlling the ratio of smelting raw material scrap steel to be 19%, and desulfurizing molten iron after pretreatment before smelting until S: 0.0277%; smelting by adopting a combined blown converter, wherein the steel-making end point C is as follows: 0.08 percent, adopting an infrared slide plate and a slag stopping cone to strictly control slag discharging during tapping, adopting 25kg/t ferrosilicon to precipitate and deoxidize, and adding 2.95kg/t steel synthetic refining slag along the steel flow during tapping 1/2;
(2) an LF refining procedure: aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 4.9kg/t steel and silicon carbide 0.8kg/t steel are added for diffusion deoxidation, fluorite 0.5kg/t steel and wollastonite 3.0kg/t steel are added for slagging, and the final slag alkalinity is as follows: 1.74 of Al2O3: 8.6 percent, recarburizing by using a recarburizing agent, keeping white slag for 25min, and transmitting electricity for 40 min;
(3) RH vacuum treatment process: in the RH vacuum treatment process, the vacuum degree is 24Pa, the vacuum maintaining time is 11min, argon is blown during the vacuum treatment, the argon flow is controlled to regulate the flow according to the fluctuation condition of the liquid level, the liquid level of the molten steel is not exposed, the soft blowing time is 18min, then an argon flow valve is closed, and the molten steel is fully kept stand until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts special ferrosilicon of 1.0kg/t steel;
(4) and (3) continuous casting process: a rectangular blank of 280mm multiplied by 380mm is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high-carbon steel mode is adopted under the tail end soft reduction; argon protection is carried out in the whole process, ladle slag tapping detection is carried out, the superheat degree is controlled to be 28 ℃, and the pulling speed is controlled to be 0.65 m/min;
(5) cogging and blooming: cogging and rolling the 280mm × 380mm rectangular billet into 150mm × 150mm square billet, wherein the heating time is 4.1h, the temperature of a heating section is 1145 ℃, and the temperature of a soaking section is 1150 ℃;
(6) grinding process, namely grinding the primary rolling blank of 150mm × 150mm by using a grinding machine, wherein the grinding amount of one side is 1.8mm, and removing a decarburized layer and the decarburized layerSurface defect, and chamfering the corner of the ground blooming blank, wherein the chamfering angle is 45 degrees0The width of the chamfered inclined plane is 8 mm;
(7) a wire rod rolling procedure: the method comprises the steps of putting a square billet with the diameter of 150mm multiplied by 150mm into a furnace, loading steel in an idle step, controlling the heating time to be 1.4h, the temperature of a heating section to be 1020 ℃, the temperature of a soaking section to be 1090 ℃, the residual oxygen content in the furnace to be 0.9 percent, controlling the finish rolling temperature to be 890 ℃, the spinning temperature to be 825 ℃ and the roller way speed to be 24m/s, and gradually increasing the inlet speed by steps and increasing the amplitude to be 1.8m/s in the high-speed wire rod rolling process.
The purity index, the center segregation index, the mechanical property index, the corrosion resistance and the performance after being made into the elastic strip are shown in the table 2, the center segregation index, the mechanical property index and the corrosion resistance respectively in the table 3, the table 4 and the table 5.
Example 5
The chemical components and the mass percentage content of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance are shown in table 1, the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling, and the specific process steps are as follows:
(1) smelting: controlling the ratio of smelting raw material scrap steel to be 18%, and desulfurizing molten iron after pretreatment before smelting until S: 0.0283%; smelting by adopting a combined blown converter, wherein the steel-making end point C is as follows: 0.10 percent, adopting an infrared slide plate and a slag stopping cone to strictly control slag discharging during tapping, adopting 25kg/t ferrosilicon to precipitate and deoxidize, and adding 2.95kg/t steel synthetic refining slag along the steel flow during tapping 1/2;
(2) an LF refining procedure: aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 4.9kg/t steel and silicon carbide 0.80kg/t steel are added for diffusion deoxidation, fluorite 0.5kg/t steel and wollastonite 3.2kg/t steel are added for slagging, and the final slag alkalinity is as follows: 1.65 of Al2O3: 9.1 percent, recarburizing by using a recarburizing agent, keeping white slag for 33min, and transmitting electricity for 35 min;
(3) RH vacuum treatment process: in the RH vacuum treatment process, the vacuum degree is 28Pa, the vacuum maintaining time is 13min, argon is blown during the vacuum treatment, the argon flow is controlled to regulate the flow according to the fluctuation condition of the liquid level, the liquid level of the molten steel is ensured not to be exposed, the soft blowing time is 17min, then an argon flow valve is closed, and the molten steel is fully kept stand until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts special ferrosilicon of 1.0kg/t steel;
(4) and (3) continuous casting process: a rectangular blank of 280mm multiplied by 380mm is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high-carbon steel mode is adopted under the tail end soft reduction; argon protection is carried out in the whole process, ladle slag tapping detection is carried out, the superheat degree is controlled to be 21 ℃, and the pulling speed is controlled to be 0.65 m/min;
(5) cogging and blooming: cogging and rolling the 280mm × 380mm rectangular billet into 150mm × 150mm square billet, wherein the heating time is 4.5h, the temperature of a heating section is 1130 ℃, and the temperature of a soaking section is 1140 ℃;
(6) grinding (including grinding 150mm × 150mm bloom with single side grinding amount of 1.5 mm) by grinding machine to remove decarburized layer and surface defect, and chamfering the corners of the ground bloom to obtain chamfered angle of 45%0The width of the chamfered inclined plane is 6 mm;
(7) a wire rod rolling procedure: the method comprises the steps of putting a 150mm square billet with the diameter of 150mm into a furnace, loading steel in an idle step mode, controlling the heating time to be 1.4h, controlling the temperature of a heating section to be 1060 ℃, the temperature of a soaking section to be 1080 ℃, the residual oxygen content in the furnace to be 1.0%, controlling the finish rolling temperature to be 900 ℃, controlling the spinning temperature to be 825 ℃ in the high-speed wire rod rolling process, adopting the inlet speed of 24m/s, and gradually increasing the speed step by step and increasing the amplitude to be 1.8m/s later.
The purity index, the center segregation index, the mechanical property index, the corrosion resistance and the performance after being made into the elastic strip are shown in the table 2, the center segregation index, the mechanical property index and the corrosion resistance respectively in the table 3, the table 4 and the table 5.
Example 6
The chemical components and the mass percentage content of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance are shown in table 1, the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling, and the specific process steps are as follows:
(1) smelting: controlling the ratio of smelting raw material scrap steel at 15%, and desulfurizing molten iron after pretreatment before smelting until S: 0.015 percent; smelting by adopting a combined blown converter, wherein the steel-making end point C is as follows: 0.08 percent, adopting an infrared slide plate and a slag stopping cone to strictly control slag discharging during tapping, adopting 15kg/t ferrosilicon to precipitate and deoxidize, and adding 2.6kg/t steel synthetic refining slag along the steel flow during tapping 1/2;
(2) an LF refining procedure: aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 6.0kg/t steel and silicon carbide 1.0kg/t steel are added for diffusion deoxidation, fluorite 1.0kg/t steel and wollastonite 3.5kg/t steel are added for slagging, and the final slag alkalinity is as follows: 1.5, Al2O3: 9.5 percent, recarburizing by using a recarburizing agent, keeping white slag for 20min, and transmitting electricity for 30 min;
(3) RH vacuum treatment process: in the RH vacuum treatment process, the vacuum degree is 30Pa, the vacuum maintaining time is 15min, argon is blown during the vacuum treatment, the argon flow is controlled to regulate the flow according to the fluctuation condition of the liquid level, the liquid level of the molten steel is ensured not to be exposed, the soft blowing time is 15min, then an argon flow valve is closed, and the molten steel is fully kept stand until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts special ferrosilicon of 1.0kg/t steel;
(4) and (3) continuous casting process: a rectangular blank of 280mm multiplied by 380mm is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high-carbon steel mode is adopted under the tail end soft reduction; argon protection is carried out in the whole process, ladle slag tapping detection is carried out, the superheat degree is controlled to be 24 ℃, and the pulling speed is controlled to be 0.65 m/min;
(5) cogging and blooming: cogging and rolling the 280mm × 380mm rectangular billet into 150mm × 150mm square billet, wherein the heating time is 4h, the temperature of a heating section is 1120 ℃, and the temperature of a soaking section is 1120 ℃;
(6) grinding (including grinding 150mm × 150mm bloom with single side grinding amount of 1.0 mm) by grinding machine, removing decarburized layer and surface defect, and chamfering corners of the ground bloom to obtain chamfered corner 35%0The width of the chamfered inclined plane is 5 mm;
(7) a wire rod rolling procedure: the method comprises the steps of putting a 150mm x 150mm square billet into a furnace, loading steel in an idle step mode, controlling the heating time to be 1h, controlling the temperature of a heating section to be 900 ℃, the temperature of a soaking section to be 1050 ℃, the residual oxygen content in the furnace to be 1.5%, controlling the finish rolling temperature to be 870 ℃ in the high-speed wire rod rolling process, controlling the spinning temperature to be 810 ℃, and controlling the roller bed speed to be 24m/s at an inlet speed, and then gradually increasing the inlet speed by steps and increasing the amplitude by 1.8 m/s.
The purity index, the center segregation index, the mechanical property index, the corrosion resistance and the performance after being made into the elastic strip are shown in the table 2, the center segregation index, the mechanical property index and the corrosion resistance respectively in the table 3, the table 4 and the table 5.
Example 7
The chemical components and the mass percentage content of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance are shown in table 1, the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling, and the specific process steps are as follows:
(1) smelting: controlling the ratio of smelting raw material scrap steel to be 20%, and desulfurizing molten iron after pretreatment before smelting until S: 0.030%; smelting by adopting a combined blown converter, wherein the steel-making end point C is as follows: 0.12 percent, adopting an infrared slide plate and a slag stopping cone to strictly control slag discharging during tapping, adopting 23kg/t ferrosilicon to precipitate and deoxidize, and adding 2.9kg/t steel synthetic refining slag along the steel flow during tapping 1/2;
(2) an LF refining procedure: aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 6.0kg/t steel and silicon carbide 0.9kg/t steel are added for diffusion deoxidation, fluorite 2.0kg/t steel and wollastonite 3.5kg/t steel are added for slagging, and the final slag alkalinity is as follows: 2.0, Al2O3: 8 percent, recarburizing by using a recarburizing agent, keeping the white slag for 22min, and transmitting electricity for 33 min;
(3) RH vacuum treatment process: in the RH vacuum treatment process, the vacuum degree is 25Pa, the vacuum holding time is 12min, argon is blown during vacuum treatment, the argon flow is controlled to regulate the flow according to the fluctuation condition of the liquid level, the liquid level of the molten steel is not exposed, the soft blowing time is 18min, then an argon flow valve is closed, and the molten steel is fully kept stand until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts special ferrosilicon of 1.0kg/t steel;
(4) and (3) continuous casting process: a rectangular blank of 280mm multiplied by 380mm is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high-carbon steel mode is adopted under the tail end soft reduction; argon protection is carried out in the whole process, ladle slag tapping detection is carried out, the superheat degree is controlled to be 20 ℃, and the pulling speed is controlled to be 0.65 m/min;
(5) cogging and blooming: cogging and rolling the 280mm × 380mm rectangular billet into 150mm × 150mm square billet, wherein the heating time is 5 hours, the temperature of a heating section is 1250 ℃, and the temperature of a soaking section is 1260 ℃;
(6) grinding (2.0 mm for single side) of × 150mm bloom with grinding amount of 2.0mm, removing decarburized layer and surface defect, and chamfering corners of the ground bloom to 55 chamfered corners0The width of the chamfered inclined plane is 8 mm;
(7) a wire rod rolling procedure: the 150mm x 150mm square billet is put into a furnace, empty-step steel loading is adopted, the heating time is controlled to be 1.5h, the temperature of a heating section is 1100 ℃, the temperature of a soaking section is 1100 ℃, the residual oxygen in the furnace is 1.2 percent, the finish rolling temperature is controlled to be 910 ℃, the spinning temperature is controlled to be 830 ℃ in the high-speed wire rod rolling process, the inlet speed is 24m/s, the later step-by-step increasing is adopted, and the increasing amplitude is 1.8 m/s.
The purity index, the center segregation index, the mechanical property index, the corrosion resistance and the performance after being made into the elastic strip are shown in the table 2, the center segregation index, the mechanical property index and the corrosion resistance respectively in the table 3, the table 4 and the table 5.
Example 8
The chemical components and the mass percentage content of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance are shown in table 1, the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling, and the specific process steps are as follows:
(1) smelting: controlling the ratio of smelting raw material scrap steel at 15%, and desulfurizing molten iron after pretreatment before smelting until S: 0.015 percent; smelting by adopting a combined blown converter, wherein the steel-making end point C is as follows: 0.08 percent, adopting an infrared slide plate and a slag stopping cone to strictly control slag discharging during tapping, adopting 25kg/t ferrosilicon to precipitate and deoxidize, and adding 3.5kg/t steel synthetic refining slag along the steel flow during tapping 1/2;
(2) an LF refining procedure: aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 4.6kg/t steel and silicon carbide 1.5kg/t steel are added for diffusion deoxidation, fluorite 0kg/t steel and wollastonite 3.1kg/t steel are added for slagging, and the final slag alkalinity is as follows: 1.5, Al2O3: 9 percent of carburant for carburant, white slag keeping time for 20min, and power transmissionThe time is 30 min;
(3) RH vacuum treatment process: in the RH vacuum treatment process, the vacuum degree is 30Pa, the vacuum maintaining time is 10min, argon is blown during the vacuum treatment, the argon flow is controlled to regulate the flow according to the fluctuation condition of the liquid level, the liquid level of the molten steel is ensured not to be exposed, the soft blowing time is 15min, then an argon flow valve is closed, and the molten steel is fully kept stand until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts 0.9kg/t steel special ferrosilicon;
(4) and (3) continuous casting process: a rectangular blank of 280mm multiplied by 380mm is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high-carbon steel mode is adopted under the tail end soft reduction; argon protection is carried out in the whole process, ladle slag tapping detection is carried out, the superheat degree is 27 ℃, and the pulling speed is controlled to be 0.70 m/min;
(5) cogging and blooming: cogging and rolling the 280mm × 380mm rectangular billet into 150mm × 150mm square billet, wherein the heating time is 4h, the temperature of a heating section is 1120 ℃, and the temperature of a soaking section is 1120 ℃;
(6) grinding (including grinding 150mm × 150mm bloom with single side grinding amount of 1.0 mm) by grinding machine, removing decarburized layer and surface defect, and chamfering corners of the ground bloom to obtain chamfered corner 35%0The width of the chamfered inclined plane is 5 mm;
(7) a wire rod rolling procedure: the method comprises the steps of putting a 150mm x 150mm square billet into a furnace, loading steel in an idle step mode, controlling the heating time to be 1h, controlling the temperature of a heating section to be 900 ℃, the temperature of a soaking section to be 1050 ℃, the residual oxygen content in the furnace to be 1.5%, controlling the finish rolling temperature to be 870 ℃ in the high-speed wire rod rolling process, controlling the spinning temperature to be 810 ℃, and controlling the roller bed speed to be 24m/s at an inlet speed, and then gradually increasing the inlet speed by steps and increasing the amplitude by 1.8 m/s.
The purity index, the center segregation index, the mechanical property index, the corrosion resistance and the performance after being made into the elastic strip are shown in the table 2, the center segregation index, the mechanical property index and the corrosion resistance respectively in the table 3, the table 4 and the table 5.
Example 9
The chemical components and the mass percentage content of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance are shown in table 1, the production process comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling, and the specific process steps are as follows:
(1) smelting: controlling the ratio of smelting raw material scrap steel to be 20%, and desulfurizing molten iron after pretreatment before smelting until S: 0.030%; smelting by adopting a combined blown converter, wherein the steel-making end point C is as follows: 0.12 percent, adopting an infrared slide plate and a slag stopping cone to strictly control slag discharging during tapping, adopting 25kg/t ferrosilicon to precipitate and deoxidize, and adding 2.5kg/t steel synthetic refining slag along the steel flow during tapping 1/2;
(2) an LF refining procedure: aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 4.0kg/t steel and silicon carbide 0.5kg/t steel are added for diffusion deoxidation, fluorite 2.5kg/t steel and wollastonite 2.5kg/t steel are added for slagging, and the final slag alkalinity is as follows: 2.0, Al2O3: 8 percent, recarburizing by using a recarburizing agent, keeping white slag for 25min, and transmitting electricity for 36 min;
(3) RH vacuum treatment process: in the RH vacuum treatment process, the vacuum degree is 25Pa, the vacuum holding time is 13min, argon blowing is selected during vacuum treatment, the argon flow is controlled to regulate the flow according to the fluctuation condition of the liquid level, the liquid level of the molten steel is ensured not to be exposed, the soft blowing time is 17min, then an argon flow valve is closed, and the molten steel is fully kept stand until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts 0.5kg/t steel special ferrosilicon;
(4) and (3) continuous casting process: a rectangular blank of 280mm multiplied by 380mm is adopted, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and electric stirring currents are 320A and 5HZ, and a high-carbon steel mode is adopted under the tail end soft reduction; argon protection is carried out in the whole process, ladle slag tapping detection is carried out, the superheat degree is controlled to be 15 ℃, and the pulling speed is controlled to be 0.60 m/min;
(5) cogging and blooming: cogging and rolling the 280mm × 380mm rectangular billet into 150mm × 150mm square billet, wherein the heating time is 5 hours, the temperature of a heating section is 1250 ℃, and the temperature of a soaking section is 1260 ℃;
(6) grinding (2.0 mm for single side) of × 150mm bloom with grinding amount of 2.0mm, removing decarburized layer and surface defect, and chamfering corners of the ground bloom to 55 chamfered corners0The width of the chamfered inclined plane is 10 mm;
(7) a wire rod rolling procedure: the 150mm x 150mm square billet is put into a furnace, empty-step steel loading is adopted, the heating time is controlled to be 1.5h, the temperature of a heating section is 1100 ℃, the temperature of a soaking section is 1100 ℃, the residual oxygen in the furnace is 1.0%, the finish rolling temperature is controlled to be 910 ℃, the spinning temperature is controlled to be 830 ℃ in the high-speed wire rod rolling process, the inlet speed is 24m/s, the later step-by-step increasing is carried out, and the amplitude is increased by 1.8 m/s.
The purity index, the center segregation index, the mechanical property index, the corrosion resistance and the performance after being made into the elastic strip are shown in the table 2, the center segregation index, the mechanical property index and the corrosion resistance respectively in the table 3, the table 4 and the table 5.
TABLE 1 comparison of the chemical composition (%)
Figure DEST_PATH_IMAGE001
The balance of the ingredients in table 1 is Fe and unavoidable impurities.
TABLE 2 examples 1-9 indexes of purity of corrosion-resistant hot-rolled spring steel wire rod with good comprehensive properties
Figure 728314DEST_PATH_IMAGE002
TABLE 3 center segregation index of corrosion-resistant hot-rolled spring steel wire rods with good comprehensive properties in examples 1 to 9
Figure DEST_PATH_IMAGE003
TABLE 4 mechanical Properties of Corrosion-resistant Hot-rolled coil rods of spring steels and comparative steels having good combinations of examples 1 to 9
Figure 488197DEST_PATH_IMAGE004
TABLE 5 comparison of Corrosion resistance of Corrosion resistant spring Steel Hot rolled wire rods with good combination of Performance examples 1-9 with that of comparative Steel
Figure DEST_PATH_IMAGE005
TABLE 6 comparison of the hot rolled corrosion resistant spring steel wire rods of examples 1-9, which have good overall properties, with the spring steel rods of comparative samples
Figure 395498DEST_PATH_IMAGE006
The above examples and implementation results show that the corrosion-resistant spring steel hot-rolled wire rod produced by the method of the invention has good comprehensive performance, and the corrosion resistance, particularly the pitting voltage, of the elastic rod produced by the heat treatment is improved by more than 0.185V.
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.

Claims (7)

1. The corrosion-resistant hot-rolled spring steel wire rod with good comprehensive performance is characterized by comprising the following chemical components in percentage by mass: c: 0.40-0.70%, Si: 1.4-1.9%, Mn: 0.5-0.8%, P is less than or equal to 0.025%, S: 0.002-0.020%, Cr: 0.80-1.50%, Ni: 0.20 to 0.50%, Cu: 0.20 to 0.50%, Nb: 0.004-0.020%, Al: 0.003-0.010 percent of the total weight of the steel, and the balance of Fe and inevitable impurities, wherein the pitting voltage of the spring steel hot-rolled wire rod is more than or equal to-0.501V, and the corrosion weight loss is less than or equal to 0.552 g; the spring steel hot-rolled wire rod is produced by the following production process: comprises the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rolling; in the cogging and blooming process, cogging and rolling a 280mm × 380mm rectangular billet into a 150mm × 150mm square billet, wherein the heating time is 4-5 h, the temperature of a heating section is 1120-1250 ℃, and the temperature of a soaking section is 1120-1260 ℃; in the grinding process, a square billet with the size of 150mm multiplied by 150mm is ground by a grinding machine, the grinding amount of a single side is 1.0-2.0 mm, a decarburized layer and surface defects are removed, corners of the ground primary rolled billet are chamfered, the chamfering angle is 35-55 degrees, and the width of the chamfering inclined plane is more than or equal to 5 mm; in the wire rolling process, a 150mm square billet is put into a furnace, steel is loaded in an idle step, the heating time is controlled to be 1.0-1.4 hours, the residual oxygen in the furnace is less than or equal to 1.5 percent, the roller table speed is controlled to be 24m/s, the roller table speed is increased step by step, the amplitude is 1.8m/s, the temperature of a heating section is 900-1100 ℃, the temperature of a soaking section is 1050-1100 ℃, the precision rolling temperature is 870-910 ℃ in the wire rolling process, and the spinning temperature is 810-830 ℃.
2. The corrosion-resistant hot-rolled spring steel wire rod with good comprehensive performance as claimed in claim 1, is characterized in that the tensile strength of the hot-rolled spring steel wire rod is not less than 1779 MPa, the yield strength of the hot-rolled spring steel wire rod is not less than 1591MPa, the reduction of area is not less than 36%, and the elongation after fracture is not less than 6.5%.
3. The production process of the spring steel hot-rolled wire rod with good comprehensive performance and corrosion resistance, which is based on the claim 1 or 2, is characterized by comprising the working procedures of smelting, LF refining, RH vacuum treatment, continuous casting, cogging and blooming, coping and wire rod rolling; in the cogging and blooming process, cogging and rolling a 280mm × 380mm rectangular billet into a 150mm × 150mm square billet, wherein the heating time is 4-5 h, the temperature of a heating section is 1120-1250 ℃, and the temperature of a soaking section is 1120-1260 ℃; in the grinding process, a square billet with the size of 150mm multiplied by 150mm is ground by a grinding machine, the grinding amount of a single side is 1.0-2.0 mm, a decarburized layer and surface defects are removed, corners of the ground primary rolled billet are chamfered, the chamfering angle is 35-55 degrees, and the width of the chamfering inclined plane is more than or equal to 5 mm; in the wire rolling process, a 150mm square billet is put into a furnace, steel is loaded in an idle step, the heating time is controlled to be 1.0-1.4 hours, the residual oxygen in the furnace is less than or equal to 1.5 percent, the roller table speed is controlled to be 24m/s, the roller table speed is increased step by step, the amplitude is 1.8m/s, the temperature of a heating section is 900-1100 ℃, the temperature of a soaking section is 1050-1100 ℃, the precision rolling temperature is 870-910 ℃ in the wire rolling process, and the spinning temperature is 810-830 ℃.
4. The production process of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance according to claim 3, characterized in that in the smelting process, the proportion of smelting raw material scrap steel in furnace raw materials is controlled to be 15-20%, molten iron is pretreated and desulfurized to S: 0.015-0.030%; smelting by adopting a combined blowing converter, wherein the steelmaking end point C is more than or equal to 0.08 percent, discharging slag by adopting double-blocking and tight control of an infrared sliding plate and a slag-stopping cone during tapping, precipitating and deoxidizing by adopting 15-25 kg/t of steel ferrosilicon, and adding 2.5-3.5 kg/t of steel synthetic refining slag along the steel flow during tapping 1/2.
5. The production process of the spring steel hot-rolled wire rod with good comprehensive performance and corrosion resistance as claimed in claim 3, wherein in the LF refining process, aluminum-free deoxidation is adopted, argon is blown at the bottom in the whole LF refining process, active lime 4.0-6.0 kg/t steel and silicon carbide 0.5-1.5 kg/t steel are added for diffusion deoxidation, fluorite 0-2.5 kg/t steel and wollastonite 2.5-3.5 kg/t steel are added for slagging, and the final slag alkalinity is as follows: 1.5 to 2.0, Al2O3Less than 10.0 percent, the carburant is used for carburant, the white slag keeping time is more than or equal to 20min, and the power transmission time is more than or equal to 30 min.
6. The production process of the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance according to any one of claims 3 to 5, characterized in that in the RH vacuum treatment process, the degree of vacuum of the RH vacuum treatment is less than or equal to 30Pa, the vacuum maintaining time is 10-15 min, argon is blown during the vacuum treatment to ensure that the liquid level of molten steel is not exposed, the soft blowing time is more than or equal to 15min, then an argon flow valve is closed, and the production process is fully kept still until a ladle is cast; in the RH vacuum treatment process, the fine-tuning silicon component adopts 0.5-1.0 kg/t steel special ferrosilicon.
7. The process for producing the corrosion-resistant spring steel hot-rolled wire rod with good comprehensive performance according to any one of claims 3 to 5, wherein the continuous casting process adopts a 280mm x 380mm rectangular blank, the crystallizer adopts the technology of electromagnetic stirring and tail end soft reduction, the electromagnetic stirring and the electric stirring currents are 320A and 5HZ, and the high-carbon steel mode is adopted at the tail end soft reduction; and (3) carrying out argon protection in the whole process, detecting slag in a ladle, controlling the superheat degree to be 15-30 ℃ and the target superheat degree: the delta T =20 ℃, the drawing speed is controlled to be 0.60-0.70 m/min, and the target drawing speed is: 0.65 m/min.
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