CN115125450B - Microalloyed spring and manufacturing process thereof - Google Patents

Microalloyed spring and manufacturing process thereof Download PDF

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Publication number
CN115125450B
CN115125450B CN202210784596.3A CN202210784596A CN115125450B CN 115125450 B CN115125450 B CN 115125450B CN 202210784596 A CN202210784596 A CN 202210784596A CN 115125450 B CN115125450 B CN 115125450B
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spring
carrying
microalloyed
rolling
billet
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CN115125450A (en
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楼芬娣
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Zhejiang Isri Shuangdi Spring Co ltd
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Zhejiang Isri Shuangdi Spring 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
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
    • B21C37/04—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire
    • B21C37/045—Manufacture of wire or bars with particular section or properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21F—WORKING OR PROCESSING OF METAL WIRE
    • B21F35/00—Making springs from wire
    • 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
    • C21C7/0006—Adding metallic additives
    • 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
    • C21C7/0025—Adding carbon material
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/06—Deoxidising, e.g. killing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—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
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • 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
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
    • 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
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • 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
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F1/00—Springs
    • F16F1/02—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant
    • F16F1/021—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant characterised by their composition, e.g. comprising materials providing for particular spring properties
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F2224/00—Materials; Material properties
    • F16F2224/02—Materials; Material properties solids
    • F16F2224/0208—Alloys
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The invention relates to a microalloyed spring and a manufacturing process thereof, belonging to the technical field of alloy springs. The spring steel comprises the following chemical components in percentage by weight: c:0.51-0.58%, si:0.47-0.55%, mn:0.80-0.92%, P is less than or equal to 0.012%, S is less than or equal to 0.008%, Y:0.010-0.018%, nb:0.022-0.030%, als:0.018 to 0.025 percent, and the balance of Fe and inevitable impurities, wherein the microstructure of the alloy is tempered sorbite and tempered troostite; the decarburization sensitivity of matrix smelting is reduced by introducing Nb, and Y element is introduced to Al 2 O 3 The modification of the inclusion and the modification of the modification reduce the segregation amount of the brittle phases such as sulfur, phosphorus and the like in the grain boundary, and the prepared spring matrix has good combination of strength and toughness.

Description

Microalloyed spring and manufacturing process thereof
Technical Field
The invention belongs to the technical field of alloy springs, and particularly relates to a microalloyed spring and a manufacturing process thereof.
Background
The spring is a key basic part in the equipment manufacturing industry, has large quantity and wide range and various varieties, is used for controlling the movement of parts and relaxing the impact or vibration and the like, and is widely applied to the fields of automobiles, railways, engineering machinery, electronic and electric appliances and the like.
The traditional spring uses high-carbon steel as a base material, the carbon content is generally 0.6-0.9% to obtain higher strength, but the toughness is insufficient, and fatigue cracks are easy to generate in the working process; therefore, in the prior art, in the process of transmissionA certain amount of alloy elements are introduced into the conventional carbon steel to meet different performance requirements, such as the existing mature spring steel series including silicon-manganese spring steel, silicon-chromium spring steel, chromium-manganese spring steel, chromium-vanadium spring steel, tungsten-chromium-vanadium spring steel and the like; however, the content of C in these steels is generally high, and in order to compensate for the C burning loss, the initial C content is designed to be high, the strengthening processing such as rolling and drawing is difficult, and the micro-cracks are easy to occur; in addition, als forms Al in the matrix 2 O 3 The inclusions are large in brittleness, high in melting point and high in hardness, and are broken into tip-end small inclusions in strengthening processing, microcracks are caused, and toughness of a matrix is influenced.
Disclosure of Invention
In order to solve the technical problems mentioned in the background art, the invention provides a microalloyed spring and a manufacturing process thereof.
The purpose of the invention can be realized by the following technical scheme:
a microalloyed spring comprises the following chemical components in percentage by weight:
c:0.51-0.58%, si:0.47-0.55%, mn:0.80-0.92%, P is less than or equal to 0.012%, S is less than or equal to 0.008%, Y:0.010-0.018%, nb:0.022-0.030%, als:0.018 to 0.025 percent, and the balance of Fe and inevitable impurities;
wherein:
the C element is a main element forming a solid solution structure in the steel, so that the isothermal transformation curve of the steel is shifted to the right, the stability of the super-cooled austenite of the steel is improved, a martensite structure is easily obtained, and the high-strength spring steel is prepared, for example, the existing steels such as No. 70 steel, T9A and the like are commonly used for manufacturing springs, but, the C content is too high, a net carburized structure is easily formed, the plasticity of the steel is rapidly reduced, the rolling and drawing performances are poor, the C content is designed to be 0.51-0.58% for matching with a rolling and drawing process, compared with the prior art, the C content is reduced, the machinability is improved while the strengthening structure is ensured to be easily obtained, and as the C content is designed to be lower and the decarburization is serious when smelting is carried out at the temperature of more than 1200 ℃, the decarburization sensitivity is reduced by introducing 0.022-0.030% of Nb;
als can effectively refine austenite grain size, remarkably improve the plasticity of steel, is beneficial to rolling and drawing of steel, but can form Al in a matrix 2 O 3 The inclusions are brittle inclusions, have high melting point and hardness, are broken into tip small inclusions in the deformation process, generate stress concentration, form cracks from the inclusions, have the Als content of 0.018-0.025 percent, are simple in material selection and process control, and are used for reducing Al content 2 O 3 The influence of the inclusion on the base material, the invention introduces a small amount of Y element which is compounded with Als to form the inclusion, and the hardness of the composite inclusion is relative to that of Al 2 O 3 Lower inclusion, spherical-like shape and Al content 2 O 3 The inclusion is modified, and the toughness of the steel is improved.
A manufacturing process of a microalloyed spring specifically comprises the following steps:
step S1, continuous casting of a billet: adding scrap steel and ferrocolumbium into blast furnace molten iron for smelting together, tapping by adopting a high-carbon-drawing process, adding a carburant to adjust the carbon content during tapping, then sequentially carrying out LF refining and RH vacuum treatment, carrying out nitrogen protection continuous casting on refined molten steel, and carrying out air cooling to prepare a billet;
further, the end point carbon content of the tapping of the high carbon-drawing process is not lower than 0.19%, and the tapping temperature is 1680 +/-20 ℃.
Further, the sulfur content of the recarburizer is not higher than 500ppm, and the nitrogen content is not higher than 200ppm.
Further, ferrosilicon and silicon carbide are used for deoxidation in the LF refining process, calcium-silicon-aluminum-based refining slag is used for refining, the alkalinity of the refining slag is 2.5-3.5, and the LF refining time is 28-35min.
Further, yttrium iron alloy is added during RH vacuum treatment to adjust the yttrium content, the vacuum degree of the RH vacuum treatment is not higher than 2mbar, and the time of the RH vacuum treatment is 18-24min.
Step S2, rolling and drawing the steel wire: preheating a billet to 600 ℃, carrying out induction heating, then continuously rolling the billet into a wire material, then carrying out induction heating again, carrying out hot drawing and sizing, removing oxide skin, then winding, softening and annealing to prepare a spring steel wire;
furthermore, the initial rolling temperature of the continuous rolling is 950 +/-20 ℃, the final rolling temperature is not lower than 880 ℃, and the total rolling deformation is not higher than 40%.
Furthermore, the hot-drawing speed is 9-15m/min, the total deformation of the hot-drawing section is not higher than 18%, and graphite powder is used as a lubricant in the hot-drawing process.
Step S3: and (3) hot rolling: preheating and softening the spring steel wire, and winding, blanking and finish machining the spring steel wire by using a spring winding machine to prepare a spring blank;
step S4, heat treatment: heating the spring blank to 860-910 ℃, preserving heat for 20-30min, transferring into quenching oil for quenching, then heating to 460-530 ℃, preserving heat for 110-140min, and air cooling to room temperature to prepare the microalloyed spring.
Furthermore, the average cooling speed of the quenching oil at 600-1000 ℃ is 70-90 ℃/s, so that the martensite structure is favorably and fully formed, and deformation and cracks are not easy to occur.
The invention has the beneficial effects that:
1. compared with the existing steel for preparing the spring, the steel for preparing the spring has the advantages that the C content is designed to be low, a net-shaped carburized structure is prevented from being formed in a matrix, the rollability and drawability of the matrix are improved, a rolling and drawing process is matched to obtain a compact and refined structure, the decarburization sensitivity of matrix smelting is reduced by introducing 0.022-0.030% of Nb, the stability of the C content is ensured, the microstructure of the prepared spring mainly comprises tempered sorbite and a small amount of tempered troostite, and the steel has good combination of strength and toughness.
2. The invention adds yttrium iron alloy during RH vacuum treatment, and 0.010-0.018 percent of yttrium element is introduced into a matrix and is mixed with Al 2 O 3 Is compounded with the inclusions of (2) to Al 2 O 3 The modification of the impurities is modified, the hardness of the composite impurities is reduced, the shape of the composite impurities is in a sphere-like shape, the brittleness of a matrix is reduced, and meanwhile, yttrium element is preferentially segregated at a grain boundary, so that the segregation amount of brittle phases such as sulfur, phosphorus and the like at the grain boundary is reduced, and the effects of purifying the grain boundary and improving the strength of the grain boundary are achieved.
3. Based on the above component design, the spring base material has good toughness, and the good plasticity of the spring base material enables hot rolling and hot drawing processes to be adopted in the forming process, so that a fine structure can be obtained from a microscopic angle, and a spring with accurate size and high surface quality can be obtained from a macroscopic angle
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a metallographic picture of a spring prepared according to example 1 of the present invention;
FIG. 2 is a metallographic picture of a spring prepared in accordance with example 2 of the present invention;
FIG. 3 is a metallographic image of a spring prepared according to example 3 of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
In this embodiment, a microalloyed spring is manufactured by the following specific implementation process:
1. continuous casting billet
a1, preparing materials: the ingredients were designed according to the following chemical composition: c:0.51%, si:0.47%, mn:0.92%, P is less than or equal to 0.012%, S is less than or equal to 0.008%, Y:0.010%, nb:0.030%, als:0.018%, the balance being Fe and unavoidable impurities;
a2, smelting: taking high-quality blast furnace molten iron, adding scrap steel and ferrocolumbium to smelt and adjust the niobium content, tapping by adopting a high-carbon-pulling process, controlling the end point carbon content of tapping to be not less than 0.19 percent, controlling the tapping temperature to be 1680 +/-20 ℃, and adding a carburant (a low-nitrogen carburant is selected, wherein the nitrogen content is not higher than 200ppm, and the sulfur content is not higher than 500 ppm) during tapping;
a3, LF refining: transferring into an LF furnace for refining after tapping, adding ferrosilicon and silicon carbide for diffusion and deoxidation, adding refining slag for refining, wherein the alkalinity of the refining slag is 2.5, and the overall refining time of LF refining is 35min;
a4, RH vacuum treatment: the vacuum degree of RH vacuum treatment is not higher than 2mbar, yttrium iron alloy is added through an alloy adding hole in the treatment process to adjust the content of yttrium element, the degassing time is not lower than 7min, and the whole treatment time is 24min;
and a5, preparing the molten steel subjected to the RH vacuum treatment into a billet by using a round billet continuous casting machine, and blowing nitrogen for protection in the whole casting process.
2. Rolled and drawn steel wire
b1, rolling: preheating a billet to 600 ℃ in a heating furnace, transferring the billet into a rolling machine, performing on-line heating by adopting high-frequency induction, controlling the initial rolling temperature to be 950 +/-20 ℃, continuously rolling the billet, reducing the diameter of the billet, and controlling the final rolling temperature to be not lower than 880 ℃, wherein the total rolling deformation is not higher than 40%;
b2, hot drawing: carrying out high-frequency induction heating on the rolled wire rod again, sequentially carrying out two-time drawing, spraying graphite powder for lubrication before each-time drawing, controlling the total deformation of the hot drawing section to be not higher than 18 percent, and carrying out sizing on the wire rod at the hot drawing speed of 9 m/min;
b3, winding: and (3) carrying out online brushing on the sized wire to remove surface oxide skin, winding the wire by using a winding machine, then placing the wire in an annealing furnace, preserving the heat for 2 hours at 380 ℃, then carrying out softening annealing along with furnace cooling, and preparing the spring steel wire.
3. Hot coil
Heating the spring steel wire to 500 ℃ for softening, automatically winding the spring steel wire at a feeding port of a spring winding machine, blanking the wound spring steel wire, and performing finish machining on the end part of the wound spring steel wire to prepare a spring blank.
4. Heat treatment of
c1, preparing quenching oil: blending with mechanical oil, and controlling the average cooling speed of the quenched part at 600-1000 ℃ to be 70-90 ℃/s;
c2, quenching: putting the spring blank into a quenching heating furnace, preserving heat for 30min at 860 ℃, and transferring into quenching oil for quenching;
c3, tempering: and (3) putting the oil-quenched workpiece into a tempering furnace, keeping the temperature at 460 ℃ for 140min, and cooling the workpiece to room temperature in air to prepare the microalloyed spring.
Example 2
In this embodiment, a microalloyed spring is manufactured by the following specific implementation process:
1. continuous casting billet
a1, preparing materials: the ingredients were designed according to the following chemical composition: c:0.55%, si:0.52%, mn:0.83 percent, P is less than or equal to 0.012 percent, S is less than or equal to 0.008 percent, Y:0.015%, nb:0.026%, als:0.025%, and the balance of Fe and inevitable impurities;
a2, smelting: taking high-quality blast furnace molten iron, adding scrap steel and ferrocolumbium to smelt and adjust the niobium content, tapping by adopting a high-carbon-pulling process, controlling the end point carbon content of tapping to be not less than 0.19 percent, controlling the tapping temperature to be 1680 +/-20 ℃, and adding a carburant (a low-nitrogen carburant is selected, wherein the nitrogen content is not higher than 200ppm, and the sulfur content is not higher than 500 ppm) during tapping;
a3, LF refining: transferring into an LF furnace for refining after tapping, adding ferrosilicon and silicon carbide for diffusion and deoxidation, adding refining slag for refining, wherein the alkalinity of the refining slag is 3.0, and the overall refining time of LF refining is 32min;
a4, RH vacuum treatment: the vacuum degree of RH vacuum treatment is not higher than 2mbar, yttrium iron alloy is added through an alloy adding hole in the treatment process to adjust the content of yttrium element, the degassing time is not lower than 7min, and the whole treatment time is 22min;
and a5, manufacturing the molten steel subjected to RH vacuum treatment into a billet by using a round billet continuous casting machine, and blowing nitrogen for protection in the whole casting process.
2. Rolled and drawn steel wire
b1, rolling: preheating a billet to 600 ℃ in a heating furnace, transferring the billet into a rolling machine, performing on-line heating by adopting high-frequency induction, controlling the initial rolling temperature to be 950 +/-20 ℃, continuously rolling the billet, reducing the diameter of the billet, and controlling the final rolling temperature to be not lower than 880 ℃, wherein the total rolling deformation is not higher than 40%;
b2, hot drawing: carrying out high-frequency induction heating on the rolled wire rod again, sequentially carrying out two-time drawing, spraying graphite powder for lubrication before each-time drawing, controlling the total deformation of the hot drawing section to be not higher than 18 percent, and carrying out sizing on the wire rod, wherein the hot drawing speed is 13 m/min;
b3, winding: and (3) carrying out online brushing on the sized wire to remove surface oxide skin, winding the wire by using a winding machine, then placing the wire in an annealing furnace, preserving the heat for 2 hours at 380 ℃, then carrying out softening annealing along with furnace cooling, and preparing the spring steel wire.
3. Hot coil
Heating the spring steel wire to 500 ℃ for softening, automatically winding the spring steel wire at a feeding port of a spring winding machine, blanking the wound spring steel wire, and performing finish machining on the end part of the wound spring steel wire to prepare a spring blank.
4. Thermal treatment
c1, preparing quenching oil: blending with mechanical oil, and controlling the average cooling speed of the quenched part at 600-1000 ℃ to be 70-90 ℃/s;
c2, quenching: putting the spring blank into a quenching heating furnace, preserving heat for 25min at 890 ℃, and transferring into quenching oil for quenching;
c3, tempering: and (3) putting the oil-quenched workpiece into a tempering furnace, preserving the heat at 500 ℃ for 120min, and cooling the workpiece to room temperature in air to prepare the microalloyed spring.
Example 3
In this embodiment, a microalloyed spring is manufactured by the following specific implementation process:
1. continuous casting billet
a1, preparing materials: the ingredients were designed according to the following chemical composition: c:0.58%, si:0.55%, mn:0.80 percent, less than or equal to 0.012 percent of P, less than or equal to 0.008 percent of S, Y:0.018%, nb:0.030%, als:0.012%, the balance being Fe and unavoidable impurities;
a2, smelting: taking high-quality blast furnace molten iron, adding scrap steel and ferroniobium for smelting to adjust the niobium content, tapping by adopting a high-carbon-drawing process, controlling the end point carbon content of tapping to be not less than 0.19 percent, controlling the tapping temperature to be 1680 +/-20 ℃, and adding a carburant (a low-nitrogen carburant is selected, wherein the nitrogen content is not more than 200ppm, and the sulfur content is not more than 500 ppm) during tapping;
a3, LF refining: transferring into an LF furnace for refining after tapping, adding ferrosilicon and silicon carbide for diffusion and deoxidation, adding refining slag for refining, wherein the alkalinity of the refining slag is 3.5, and the overall refining time of LF refining is 28min;
a4, RH vacuum treatment: the vacuum degree of RH vacuum treatment is not higher than 2mbar, yttrium iron alloy is added through an alloy adding hole in the treatment process to adjust the content of yttrium element, the degassing time is not lower than 7min, and the whole treatment time is 18min;
and a5, manufacturing the molten steel subjected to RH vacuum treatment into a billet by using a round billet continuous casting machine, and blowing nitrogen for protection in the whole casting process.
2. Rolled and drawn steel wire
b1, rolling: preheating a billet to 600 ℃ in a heating furnace, transferring the billet into a rolling machine, performing on-line heating by adopting high-frequency induction, controlling the initial rolling temperature to be 950 +/-20 ℃, continuously rolling the billet, reducing the diameter of the billet, and controlling the final rolling temperature to be not lower than 880 ℃, wherein the total rolling deformation is not higher than 40%;
b2, hot drawing: carrying out high-frequency induction heating on the rolled wire rod again, sequentially carrying out two-time drawing, spraying graphite powder for lubrication before each-time drawing, controlling the total deformation of the hot drawing section to be not higher than 18 percent, and carrying out sizing on the wire rod at the hot drawing speed of 9-15 m/min;
b3, winding: and (3) carrying out online brushing on the sized wire to remove surface oxide skin, winding the wire by using a winding machine, then placing the wire in an annealing furnace, preserving the heat for 2 hours at 380 ℃, then carrying out softening annealing along with furnace cooling, and preparing the spring steel wire.
3. Hot coil
Heating the spring steel wire to 550 ℃ for softening, automatically winding the spring steel wire at a feeding port of a spring winding machine, blanking the wound spring steel wire, and performing finish machining on the end part of the wound spring steel wire to prepare a spring blank.
4. Thermal treatment
c1, preparing quenching oil: blending with mechanical oil, and controlling the average cooling speed of the quenched part at 600-1000 ℃ to be 70-90 ℃/s;
c2, quenching: putting the spring blank into a quenching heating furnace, preserving heat for 20min at 910 ℃, and transferring into quenching oil for quenching;
c3, tempering: and (3) putting the oil-quenched workpiece into a tempering furnace, preserving the heat at 530 ℃ for 110min, and cooling the workpiece to room temperature in air to prepare the microalloyed spring.
Taking the microalloyed springs prepared in the examples 1 to 3, and cutting a sample along the extending direction of the spring to prepare a metallographic phase, wherein the specific metallographic phase is shown in figures 1 to 3;
according to a metallographic graph, the microstructure of the microalloyed spring prepared by the method mainly comprises tempered sorbite and a small amount of tempered troostite.
The microalloyed springs prepared in the examples 1 to 3 are sampled and subjected to performance test, and the specific test data are shown in the table 1;
TABLE 1
Rm/MPa Rp0.2/MPa A/％ Z/％ Mean fatigue cycle
Example 1 1685 1531 10.3 37.1 271.831
Example 2 1723 1567 12.6 41.3 286.148
Example 3 1708 1551 11.4 39.8 275.943
As can be seen from the data in Table 1, the substrate of the microalloyed spring prepared by the invention has good combination of strength and toughness.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is merely exemplary and illustrative of the principles of the present invention and various modifications, additions and substitutions of the specific embodiments described herein may be made by those skilled in the art without departing from the principles of the present invention or exceeding the scope of the claims set forth herein.

Claims (9)

1. A microalloyed spring is characterized by comprising the following chemical components in percentage by weight: c:0.51-0.58%, si:0.47-0.55%, mn:0.80-0.92%, P is less than or equal to 0.012%, S is less than or equal to 0.008%, Y:0.010-0.018%, nb:0.022-0.030%, als:0.018 to 0.025 percent, and the balance of Fe and inevitable impurities, wherein yttrium iron alloy is added during RH vacuum treatment to adjust the yttrium content, and the microstructures of the yttrium iron alloy comprise tempered sorbite and tempered troostite;
the manufacturing process of the microalloyed spring comprises the following steps:
step S1, continuous casting of a billet: adding scrap steel and ferrocolumbium into blast furnace molten iron for smelting together, tapping by adopting a high-carbon-drawing process, adding a carburant to adjust the carbon content during tapping, then sequentially carrying out LF refining and RH vacuum treatment, carrying out nitrogen protection continuous casting on refined molten steel, and carrying out air cooling to prepare a billet;
step S2, rolling and drawing the steel wire: preheating a billet to 600 ℃, carrying out induction heating, then continuously rolling the billet into a wire material, then carrying out induction heating again, carrying out hot drawing and sizing, removing oxide skin, then winding, softening and annealing to prepare a spring steel wire;
step S3: and (3) hot rolling: preheating and softening the spring steel wire, and winding, blanking and finish machining the spring steel wire by using a spring winding machine to prepare a spring blank;
step S4, heat treatment: heating the spring blank to 860-910 ℃, preserving heat for 20-30min, transferring into quenching oil for quenching, then heating to 460-530 ℃, preserving heat for 110-140min, and air cooling to room temperature to prepare the microalloyed spring.
2. A process for manufacturing a microalloyed spring according to claim 1, wherein the process includes the steps of:
step S1, continuous casting of a billet: adding scrap steel and ferrocolumbium into blast furnace molten iron for smelting together, tapping by adopting a high-carbon-drawing process, adding a carburant to adjust the carbon content during tapping, then sequentially carrying out LF refining and RH vacuum treatment, carrying out nitrogen protection continuous casting on refined molten steel, and carrying out air cooling to prepare a billet;
step S2, rolling and drawing the steel wire: preheating a billet to 600 ℃, carrying out induction heating, then continuously rolling the billet into a wire material, then carrying out induction heating again, carrying out hot drawing and sizing, removing oxide skin, then winding, softening and annealing to prepare a spring steel wire;
step S3: and (3) hot rolling: preheating and softening the spring steel wire, and winding, blanking and finish machining the spring steel wire by using a spring winding machine to prepare a spring blank;
step S4, heat treatment: heating the spring blank to 860-910 ℃, preserving heat for 20-30min, transferring into quenching oil for quenching, then heating to 460-530 ℃, preserving heat for 110-140min, and air cooling to room temperature to prepare the microalloyed spring.
3. The manufacturing process of a microalloyed spring as claimed in claim 2, wherein the tapping temperature is 1680 ± 20 ℃ and the final carbon content is not lower than 0.19% in the high carbon-drawing process.
4. The process for producing a microalloyed spring according to claim 2, wherein the recarburizer has a sulfur content of not more than 500ppm and a nitrogen content of not more than 200ppm.
5. The manufacturing process of a microalloyed spring according to claim 2, wherein ferrosilicon and silicon carbide are used for deoxidation in the LF refining process, calcium-silicon-aluminum-based refining slag is used for refining, the alkalinity of the refining slag is 2.5-3.5, and the LF refining time is 28-35min.
6. The manufacturing process of a microalloyed spring according to claim 2, wherein the degree of vacuum of the RH vacuum treatment is not more than 2mbar, and the time of the RH vacuum treatment is 18-24min.
7. The manufacturing process of a microalloyed spring according to claim 2, wherein the initial rolling temperature of continuous rolling is 950 ± 20 ℃, the final rolling temperature is not lower than 880 ℃, and the total rolling deformation is controlled to be not higher than 40%.
8. The process for manufacturing a microalloyed spring according to claim 2, wherein the hot drawing speed is 9-15m/min, the total deformation of the hot drawing section is not higher than 18%, and graphite powder is used as a lubricant in the hot drawing process.
9. The process for manufacturing a microalloyed spring as claimed in claim 2, wherein the quenching oil has an average cooling rate of 70 to 90 ℃/s at 600 to 1000 ℃.
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