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CN112725688A - Cold and hot dual-purpose steel for thread rolling die and preparation method thereof - Google Patents

Cold and hot dual-purpose steel for thread rolling die and preparation method thereof Download PDF

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Publication number
CN112725688A
CN112725688A CN202011342443.0A CN202011342443A CN112725688A CN 112725688 A CN112725688 A CN 112725688A CN 202011342443 A CN202011342443 A CN 202011342443A CN 112725688 A CN112725688 A CN 112725688A
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temperature
steel
forging
tempering
cold
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CN112725688B (en
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张雲飞
樊明强
赵英利
嵇爽
任帅
吕达
徐梓真
郭福在
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HBIS Co Ltd
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HBIS 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
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/002—Hybrid process, e.g. forging following casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
    • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
    • B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
    • B21J5/08—Upsetting
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • 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
    • C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/773—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material under reduced pressure or 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0075—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rods of limited length
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
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    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • 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
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  • Heat Treatment Of Steel (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

A cold and hot dual-purpose steel for a thread rolling die and a preparation method thereof belong to the technical field of metallurgy. The steel for the thread rolling die comprises the following chemical components in percentage by mass: 0.48 to 0.52%, Si: 0.8-1.2%, Mn: 0.3-0.5%, Cr: 4.0-4.5%, Mo: 1.6-2.0%, V: 0.85-1.2%, P is less than or equal to 0.015%, S is less than or equal to 0.01%, W: 0.3-0.5%, B: 0.002-0.005% of Fe and inevitable impurities as the rest; the carbon saturation Ac: 0.74-1.00. The preparation method comprises the working procedures of smelting, electroslag remelting, high-temperature homogenization, forging, superfine treatment and thermal refining. According to the invention, through optimizing alloy components, on the basis of ensuring high hardness and high wear resistance, the impact toughness and the thermal stability of the die steel are improved, and the use requirements of cold and hot dual-purpose steel for the thread rolling die are met.

Description

Cold and hot dual-purpose steel for thread rolling die and preparation method thereof
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to cold and hot dual-purpose steel for a thread rolling die and a preparation method thereof.
Background
The die steel can be divided into four categories according to the service conditions of the die, namely cold-work die steel, hot-work die steel, plastic die steel and plastic die steel. The cold-work die steel and the hot-work die steel are main die materials used for metal forming. The cold-work die steel is low in use temperature, generally lower than 100 ℃, large in working stress of the die, severe in working condition, and high in hardness, high in wear resistance and strong in seizure resistance, and the common cold-work die steel is Cr12 type steel, the carbon content of the common cold-work die steel is 1.45-2.3%, and the chromium content of the common cold-work die steel is 11-13%. The hot-work die steel is high in use temperature, generally 300-650 ℃, in contact with liquid metal or high-temperature metal, is under the action of cyclic thermal stress, is severe in working condition, and requires high thermal stability, thermal fatigue resistance, red hardness and good thermal conductivity, and the common hot-work die steel is H-series steel, the carbon content of the common hot-work die steel is 0.32-0.52%, and the total alloy content is 8-12%. Different die materials are usually selected for preparation aiming at different processing requirements, and the common die materials have poor applicability. In order to improve the applicability of the die material, expand the application range and reduce the production cost, the die material which can be used as both cold and hot materials is successfully developed to meet increasingly harsh processing environments.
Patent application with publication number CN108018500A discloses cold and hot combined die steel and a preparation process thereof, wherein the die steel comprises the following components: 0.55-0.65%, Si: 0.85-1.15%, Cr: 3.7-4.4%, Mo: 1.8-2.2%, V: 1.3-1.7%, W: 1.9-2.2%; the method strictly controls component segregation by spray forming, and simultaneously crushes large-particle carbide by twice forging, thereby improving the impact toughness and plasticity of steel. Obviously, the injection molding technology has obvious technical and economic advantages compared with the traditional casting and powder metallurgy, and the steel ingot prepared by injection molding can obtain an internal structure with uniform and fine carbide and no macrosegregation. However, at present, the spray forming technology is still in the initial stage of industrial production, the basic theory research is still incomplete, the requirements on equipment and a spray process are high, and the popularization and the application are limited.
Patent application publication No. CN103276298A discloses a high-hardness high-toughness cold and hot combined die steel and a production method thereof, wherein the die steel comprises the following components: 0.5-0.65%, Si: 0-0.35%, Mn: 0.20-0.50%, Cr: 5.00-6.00%, Mo, 1.00-2.30%, W: 0-1.50%, V: 0.40-1.00 percent of Nb, less than or equal to 0.25 percent of Nb, less than or equal to 1.00 percent of Co, less than or equal to 0.025 percent of P, and less than or equal to 0.010 percent of S; the weight percentage of Mo +0.55W is 1.80-2.30%, and the carbon saturation Ac: 0.90-1.10. On the basis of the components of H13 steel, the die steel improves the content of C, the total content of W, Mo and V alloys, ensures the enhanced secondary hardening capacity, and improves the hardness, strength and tempering softening resistance of the steel. The Ac value of 0.90-1.10 is in a higher level, which shows that the carbon content is higher, the uneven distribution of carbide is easier to occur, the quantity of brittle residual carbide is higher, and the plasticity and toughness of the material are reduced. Meanwhile, the die steel emphasizes the secondary hardening effect when (Mo + 0.55W) reaches 1.80-2.30%, the secondary hardening effect of V is weakened, VC precipitated by secondary tempering contributes most to the wear resistance, and V also has the function of grain refining, so that the content of V is ensured to be at a higher level on the premise of not having a good V substitution scheme if the high wear resistance of the die steel is required to be ensured.
The thread rolling wheel is a tool for rolling threads on a thread rolling machine by using a metal plastic deformation method, and the material of the thread rolling wheel is cold-work die steel such as Cr12MoV, DC53, GM and the like. The thread rolling wheel needs to bear larger periodic radial extrusion force, torque and friction force in the circumferential direction in the use process, and the working condition is worse. Failure analysis shows that the tooth breakage and the end face breakage are two main failure modes of the Cr12MoV high-strength thread rolling wheel, the ratio of the tooth breakage and the end face breakage is nearly 90%, and besides the influence of a processing technology and the design of the thread rolling wheel, the main failure reasons are poor toughness and weak impact resistance of the thread rolling wheel material. Along with the gradual improvement of the strength of the processed material, the cooling in the rolling process is not timely, the requirements on the performance of the thread rolling wheel material are higher and higher, the material is required to have high hardness and high wear resistance, and higher toughness and softening resistance are important indexes for prolonging the service life of the thread rolling wheel.
Therefore, the development of the cold and hot dual-purpose thread rolling die steel which has excellent comprehensive performance, is convenient for large-scale production and is suitable for working at higher temperature and the preparation method thereof have important practical significance.
Disclosure of Invention
In order to solve the technical problems, the invention provides cold and hot dual-purpose steel for a thread rolling die and a preparation method thereof. By optimizing alloy components and refining crystal grains, the impact toughness and the thermal stability of the die steel are improved on the basis of ensuring high hardness and high wear resistance, and the use requirements of cold and hot die steel are met.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the cold and hot dual-purpose steel for the thread rolling die comprises the following chemical components in percentage by mass: 0.48 to 0.52%, Si: 0.8-1.2%, Mn: 0.3-0.5%, Cr: 4.0-4.5%, Mo: 1.6-2.0%, V: 0.85-1.2%, P is less than or equal to 0.015%, S is less than or equal to 0.01%, W: 0.3-0.5%, B: 0.002-0.005%, and the balance of Fe and inevitable impurities, wherein the carbon saturation Ac: 0.74-1.00.
In the design of the components of the cold and hot combined die steel, the total amount of W, Mo and V alloy is increased, the secondary hardening effect is enhanced, the hardness, the wear resistance and the tempering resistance stability of the steel are improved, the addition ratio of Mo and W is adjusted, Mo is increased, W is reduced, a small amount of B element is added, the hardenability is improved, and the quenching strength and the plasticity are improved. The action mechanism of part of elements is as follows:
(1) cr, B: in the steel of the invention, Cr and B mainly play a role in ensuring the hardenability of the steel, and higher hardenability is a necessary prerequisite for producing large-section die materials. Cr (chromium) component23C6The secondary carbide can improve the high-temperature strength and the wear resistance of the steel, but Cr can increase the unevenness of the carbide, so that metastable eutectic carbide appears in the steel, the eutectic carbide is not easy to deform, belongs to a hard and brittle phase, can crack a matrix and reduces the toughness of the steel. Research shows that the addition of 0.001-0.003% of B is equivalent to 0.7% of Cr in the aspect of improving hardenability, and the hot brittleness phenomenon of steel is caused when the content of B exceeds 0.007%. Accordingly, the content of B is controlled to be 0.002-0.005%, and the content of Cr is controlled to be 4.0-4.5%.
(2) Mo, W: in the steel of the present invention, Mo and W mainly act to strengthen the secondary hardening effect at the time of tempering, and to improve the heat resistance and red hardness. Mo can refine crystal grains and reduce the unevenness of eutectic carbide. The contribution of W to improving the red hardness is larger, the contribution of Mo to improving the toughness is larger, the use temperature of the thread rolling wheel is much lower than that of a common hot-working die, the requirement of materials on improving the toughness is stronger, the relative content of the alloy is adjusted by adopting a method of improving Mo and reducing W during alloy design, the content range of Mo is controlled to be 1.6-2.0%, and the content range of W is controlled to be 0.3-0.5%.
(3) V: v is a strong carbide forming element, MC type carbide precipitated secondarily is stable and not easy to aggregate and grow, the solid solution strengthening effect of the steel is improved, and the wear resistance is greatly contributed. V can refine grains and is very beneficial to improving the toughness of steel. Excessive V forms eutectic carbide among dendrites of the matrix, the eutectic carbide cannot be completely eliminated through high-temperature homogenization and multidirectional forging, and the residual eutectic carbide is easy to form segregation near crystal boundaries in the tempering process, so that the crystal boundaries are weakened, and the toughness of the steel is reduced. In order to ensure the wear resistance of the steel, the content of V is controlled to be 0.85-1.2%.
(4) Si: si is added into the die steel, so that the heat strength and the tempering resistance can be improved, and the matrix can be strengthened. The Si content is too high, a banded structure is easily formed, the material anisotropy is caused, and meanwhile, the plasticity and toughness of the material can be obviously reduced, so that the Si content is controlled to be 0.8-1.2%.
(5) Mn: mn is not a main strengthening element of the steel, is usually added as a deoxidizer, has high affinity with S, forms MnS with certain plasticity, reduces the risk of hot brittleness, and controls the content range of Mn to be 0.3-0.5%.
(6) P: p increases the cold brittleness of the die steel, strongly reduces the plasticity and cold bending property of the steel, and the content of P should be reduced as much as possible. The P content of the high-grade high-quality steel is controlled to be less than or equal to 0.025 percent, the steel of the invention aims to obtain high-strength and high-toughness cold and hot die steel, higher requirements are put on the control of the P content, and the P content range is less than or equal to 0.015 percent.
(7) S: s increases the hot brittleness of the die steel, reduces the toughness and the ductility of the steel, and reduces the transverse mechanical property of the steel because the MnS and other non-metallic inclusions extend along the deformation direction. The electroslag remelting can obviously reduce the S content, and the S content in the steel is controlled to be less than or equal to 0.01 percent.
(8) C: c is an element which contributes most to the strength of the steel, and is dissolved in the steel to form a gap solid solution and play a role in solid solution strengthening; and the precipitate strengthening effect is achieved when the precipitate forms carbide precipitation with strong carbide forming elements such as Cr, Mo, V and the like. Meanwhile, the content of C is the only factor influencing the hardenability of the steel, and compared with hot-work die steel which focuses on high-temperature strength and cold-heat fatigue performance, the cold-heat die steel has the advantages of higher strength and stronger wear resistance, and the content of C and carbide forming elements is inevitably increased.
In alloy tool and die steel, the tempering secondary hardening capacity of the steel is commonly expressed by carbon saturation Ac.
Ac=CFruit of Chinese wolfberry/Cs；
Cs=0.033W+0.063Mo+0.060Cr+0.2V；
Wherein Ac is the carbon saturation, CFruit of Chinese wolfberryCs is the balance carbon of the steel, which is the actual carbon content of the steel.
Research shows that the C content ranges from 0.50% to 0.60%, the quenching martensite hardness can stably reach above 58HRC, the ideal hardness of the steel is 62-65 HRC, the secondary hardening effect of the steel is considered, uneven carbide distribution caused by overhigh carbon content is avoided, and the C content of the steel is selected to be in the lower limit range, namely about 0.50%. According to the steel of the invention, alloy components are designed, and the calculated Cs value range is 0.5107-0.6525.
According to the relationship between the Ac value and the secondary hardening effect of the high-speed steel provided by the treatise on the influence of carbon saturation on the secondary hardening effect of the alloy tool steel from Zhao Zhaoqiang, Hu Feng and Zhang Niang, the Ac value is above 0.70, and the actual hardness value can be above 63.0 HRC. In order to obtain the heat treatment hardness of 62-65 HRC, the Ac value is appropriate, the secondary hardening capacity of the steel is improved, and the carbon saturation Ac value is set to be 0.74-1.00, namely the C content is controlled to be 0.48-0.52.
The invention also provides a preparation method of the cold and hot dual-purpose steel for the thread rolling die, which comprises the following steps:
(1) smelting: smelting the ingredients, refining, vacuum degassing and casting into electrode bars;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode bar to obtain an electroslag ingot, and carrying out stress relief annealing at the heating temperature of 750-780 ℃ for 2-4 h;
(3) high-temperature homogenization: performing high-temperature homogenization treatment on the electroslag ingot, wherein the heating temperature is 1220-1260 ℃, the heat preservation time is (0.3-0.4) × D hours, D is the diameter cm of the electroslag ingot, and then, furnace cooling is performed to the forging temperature of 1160 +/-10 ℃;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1160 +/-10 ℃, the heat preservation time is 4-6 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, and the forged pit is cooled to be less than or equal to 300 ℃;
(5) ultra-fining treatment: carrying out superfine treatment on the obtained forging stock, normalizing and heating at 1040 +/-10 ℃, preserving heat for 0.05-0.1 multiplied by d hours, and air-cooling to room temperature; annealing and heating at 860 +/-10 ℃, preserving heat (0.4-0.5) x d hours, cooling to 730 +/-10 ℃ along with the furnace, preserving heat (0.6-0.75) x d hours, cooling to be less than or equal to 500 ℃ in the furnace, and then discharging and air cooling; d is the effective size cm of the forging material;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1060-1100 ℃, keeping the temperature for 0.1-0.15 x d hours, wherein d is the effective size cm of the forged material, and carrying out vacuum gas quenching to room temperature; tempering temperature is 560 +/-10 ℃, tempering time is 2-4 h each time, three times of tempering are carried out, and the sample is cooled to room temperature after each time of tempering.
Further, in the step (1), an electric arc furnace or an intermediate frequency furnace is adopted for smelting.
Furthermore, in the step (4), upsetting deformation is carried out at a temperature of more than 1000 ℃, the first upsetting ratio is more than or equal to 2, and the total forging ratio is more than or equal to 10.
The hot and cold steel produced in the steps (1) to (5) is used as a steel bar phi of 100-200 mm for a thread rolling die, and after core sampling, quenching and tempering are carried out according to the step (6), wherein the tempering hardness is 62-65 HRC; the standard Charpy impact specimen with the thickness of 10mm multiplied by 55mm is processed, the transverse impact energy is more than or equal to 8J, and the transverse-longitudinal impact energy ratio is more than or equal to 0.8.
Sampling the core of a bar material of Cr12MoV steel with the diameter of 100 mm-200 mm, heating at 1030 ℃ for 30min, and performing vacuum gas quenching; tempering at 200 ℃ for 2h, and then tempering to obtain the tempered hardness of 58-61 HRC; the standard Charpy impact specimen with the transverse impact energy of more than or equal to 2J is processed into a standard Charpy impact specimen with the thickness of 10mm multiplied by 55 mm.
Compared with the common steel for the thread rolling die, the Cr12MoV steel has the advantages that the hardness of the steel for the thread rolling die is improved, and meanwhile, the good toughness is obtained.
The invention has the beneficial effects that: the steel disclosed by the invention has the advantages that the alloy components are optimized, the secondary hardening effect is improved, the comprehensive mechanical property which is more excellent than that of Cr12MoV steel is obtained, and the impact toughness is improved by nearly 3 times while the hardness is high at 62-65 HRC. The steel for the thread rolling die is suitable for producing and manufacturing the thread rolling wheel required by thread rolling processing of high-strength threaded steel, the failure probability of tooth breakage and end face breakage of the thread rolling wheel can be reduced due to high toughness, the end face abrasion loss can be reduced due to high strength and high wear resistance, and higher thread precision is ensured.
Detailed Description
The present invention will be described in further detail with reference to examples.
Example 1
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an electric arc furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode rod to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 750 ℃, and the heat preservation time is 4 hours;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, heating to 1220 ℃, keeping the temperature for 12h, and then furnace-cooling to the forging temperature 1150 ℃;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1150 ℃, the heat preservation is carried out for 6 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a bar with the diameter of phi 100mm, and the pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2, and the total forging ratio is 17;
(5) ultra-fining treatment: carrying out superfine treatment on the obtained forging stock, normalizing and heating at 1030 ℃, preserving heat for 1h, and cooling to room temperature; the annealing heating temperature is 869 ℃, the heat preservation is carried out for 4 hours, the temperature is reduced to 739 ℃ along with the furnace, the heat preservation is carried out for 6 hours, and the furnace is discharged and cooled by air after being cooled to be less than or equal to 500 ℃;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1060 ℃, keeping the temperature for 1.5h, and carrying out vacuum gas quenching to room temperature; tempering at 560 ℃ for 4h each time, carrying out three times of tempering, and cooling the sample to room temperature after each time of tempering.
The hot and cold steel produced according to the steps (1) to (5) is used as the steel phi 100mm bar of the thread rolling die, and after sampling at the core part, the quenching and tempering treatment is carried out according to the step (6), and the tempering hardness is 62.1 HRC; processed into standard Charpy impact test samples of 10mm multiplied by 55mm, the transverse impact energy is 8.8J, and the transverse and longitudinal impact energy ratio is 0.87.
Example 2
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an electric arc furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode rod to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 780 ℃, and the heat preservation time is 2 hours;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, heating at 1260 ℃, keeping the temperature for 9h, and then furnace-cooling to the forging temperature 1170 ℃;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1170 ℃, the heat preservation is carried out for 4 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a bar with the diameter of 100mm, and the pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2.5, and the total forging ratio is 17;
(5) ultra-fining treatment: carrying out superfine treatment on the obtained forging stock, normalizing and heating at 1050 ℃, preserving heat for 0.5h, and cooling to room temperature; the annealing heating temperature is 852 ℃, the heat preservation time is 5 hours, the furnace cooling is carried out to 720 ℃, the heat preservation time is 7.5 hours, and the furnace cooling is carried out to be less than or equal to 500 ℃, and then the furnace is taken out for air cooling;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1100 ℃, preserving heat for 1h, and carrying out vacuum gas quenching to room temperature; tempering at 570 ℃ for 2h each time, carrying out three times of tempering, and cooling the sample to room temperature after each time of tempering.
The hot and cold steel produced according to the steps (1) to (5) is used as the steel phi 100mm bar of the thread rolling die, and after sampling at the core part, the quenching and tempering treatment is carried out according to the step (6), and the tempering hardness is 64.9 HRC; processed into standard Charpy impact test samples of 10mm multiplied by 55mm, the transverse impact energy is 8.1J, and the transverse and longitudinal impact energy ratio is 0.80.
Example 3
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an electric arc furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out electroslag remelting on the electrode rod in a protective atmosphere to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 770 ℃ and the heat preservation time is 2.5 h;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, heating the electroslag ingot at 1250 ℃, keeping the temperature for 10 hours, and then cooling the electroslag ingot to 1155 ℃ in a furnace;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1155 ℃, the heat preservation time is 5.7 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a phi 200mm bar, and the pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2.5, and the total forging ratio is 10.25;
(5) ultra-fining treatment: performing superfine treatment on the obtained forging stock, normalizing and heating at 1048 ℃, preserving heat for 1h, and cooling to room temperature; annealing and heating at 865 ℃, preserving heat for 10 hours, cooling to 725 ℃ along with the furnace, preserving heat for 15 hours, discharging and air cooling after the furnace is cooled to be less than or equal to 500 ℃;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1090 ℃, preserving heat for 2 hours, and carrying out vacuum gas quenching to room temperature; tempering at 570 ℃ for 2h each time, carrying out three times of tempering, and cooling the sample to room temperature after each time of tempering.
The cold and hot dual-purpose steel phi 200mm bar material produced according to the steps (1) to (5) is used as the steel phi 200mm bar material for the thread rolling die, and after core sampling, quenching and tempering are carried out according to the step (6), and the tempering hardness is 63.6 HRC; the sample is processed into a standard Charpy impact sample with the thickness of 10mm multiplied by 55mm, the transverse impact energy is 8.4J, and the transverse and longitudinal impact energy ratio is 0.82.
Example 4
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an electric arc furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode rod to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 760 ℃, and the heat preservation time is 3.5 h;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, heating the electroslag ingot to 1230 ℃, keeping the temperature for 11 hours, and then cooling the electroslag ingot to the forging temperature 1165 ℃;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1165 ℃, the heat preservation time is 4.4 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a phi 200mm bar, and the pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2.5, and the total forging ratio is 10;
(5) ultra-fining treatment: carrying out superfine treatment on the obtained forging stock, normalizing and heating at the temperature of 1034 ℃, preserving heat for 1.8h, and cooling to room temperature; the annealing heating temperature is 855 ℃, the temperature is kept for 8 hours, the temperature is reduced to 733 ℃ along with the furnace, the temperature is kept for 12 hours, and the furnace is discharged and cooled by air after the furnace is cooled to be less than or equal to 500 ℃;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1070 ℃, preserving heat for 2.9h, and carrying out vacuum gas quenching to room temperature; tempering at 550 ℃ for 4h each time, carrying out tempering for three times, and cooling the sample to room temperature after each tempering.
The cold and hot steel phi 200mm bar produced according to the steps (1) to (5) is used as the steel for the thread rolling die, and after sampling at the core part, the quenching and tempering treatment is carried out according to the step (6), and the tempering hardness is 63.4 HRC; processed into standard Charpy impact test samples of 10mm multiplied by 55mm, the transverse impact energy is 8.0J, and the transverse and longitudinal impact energy ratio is 0.83.
Example 5
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an electric arc furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode bar to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 766 ℃, and the heat preservation time is 3 h;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, heating to 1240 ℃, preserving heat for 10 hours, and then furnace-cooling to 1170 ℃ of forging temperature;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1170 ℃, the heat preservation is carried out for 4 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a phi 150mm bar, and the pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2.5, and the total forging ratio is 13.5;
(5) ultra-fining treatment: performing superfine treatment on the obtained forged material, normalizing and heating at 1042 ℃, preserving heat for 1.3h, and cooling to room temperature; annealing and heating at 861 ℃, preserving heat for 7h, cooling to 737 ℃ along with the furnace, preserving heat for 10h, discharging from the furnace and air cooling after the furnace is cooled to be less than or equal to 500 ℃;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1080 ℃, preserving heat for 2 hours, and carrying out vacuum gas quenching to room temperature; tempering at 560 ℃, tempering for 3h each time, performing tempering for three times, and cooling the sample to room temperature after each tempering.
The hot and cold steel produced according to the steps (1) to (5) is used as the phi 150mm bar of the steel for the thread rolling die, and after sampling at the core part, the hot and cold steel is subjected to quenching and tempering treatment according to the step (6), wherein the tempering hardness is 54.6 HRC; processed into standard Charpy impact test samples with the thickness of 10mm multiplied by 55mm, the transverse impact energy is 8.2J, and the transverse and longitudinal impact energy ratio is 0.87.
Example 6
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an intermediate frequency furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode rod to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 750 ℃, and the heat preservation time is 4 hours;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, heating at 1260 ℃, keeping the temperature for 9h, and then furnace-cooling to a forging temperature of 1157 ℃;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1157 ℃, the heat preservation time is 5.5h, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a bar with the diameter of phi 100mm, and a pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2, and the total forging ratio is 18;
(5) ultra-fining treatment: carrying out superfine treatment on the obtained forging stock, normalizing and heating at 1050 ℃, preserving heat for 0.5h, and cooling to room temperature; annealing and heating at 850 ℃, preserving heat for 5h, cooling to 722 ℃ along with the furnace, preserving heat for 7.5h, discharging from the furnace and air cooling after the furnace is cooled to be less than or equal to 500 ℃;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1065 ℃, preserving heat for 1.5h, and carrying out vacuum gas quenching to room temperature; tempering at 562 ℃ for 2h each time, carrying out tempering for three times, and cooling the sample to room temperature after each tempering.
The hot and cold steel produced according to the steps (1) to (5) is used as the steel phi 100mm bar of the thread rolling die, and after sampling at the core part, the quenching and tempering treatment is carried out according to the step (6), and the tempering hardness is 62.7 HRC; processed into standard Charpy impact test samples of 10mm multiplied by 55mm, the transverse impact energy is 8.3J, and the transverse and longitudinal impact energy ratio is 0.86.
Example 7
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an intermediate frequency furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode rod to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 780 ℃, and the heat preservation time is 2 hours;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, heating to 1220 ℃, keeping the temperature for 12h, and then furnace-cooling to the forging temperature 1165 ℃;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1165 ℃, the heat preservation time is 4.8 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a bar with the diameter of phi 100mm, and a pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2.5, and the total forging ratio is 17.5;
(5) ultra-fining treatment: carrying out superfine treatment on the obtained forged material, normalizing and heating at 1036 ℃, preserving heat for 1h, and cooling to room temperature by air; the annealing heating temperature is 868 ℃, the heat preservation is carried out for 4h, the furnace is cooled to 737 ℃, the heat preservation is carried out for 6.5h, and the furnace is taken out and air-cooled after being cooled to be less than or equal to 500 ℃;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1095 ℃, preserving heat for 1h, and carrying out vacuum gas quenching to room temperature; tempering temperature is 552 ℃, tempering time is 4 hours each time, three times of tempering are carried out, and the sample is cooled to room temperature after each time of tempering.
The hot and cold steel produced according to the steps (1) to (5) is used as the steel phi 100mm bar of the thread rolling die, and after sampling at the core part, the quenching and tempering treatment is carried out according to the step (6), and the tempering hardness is 64.3 HRC; processed into standard Charpy impact test samples of 10mm multiplied by 55mm, the transverse impact energy is 8.5J, and the transverse and longitudinal impact energy ratio is 0.83.
Example 8
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an intermediate frequency furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode bar to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 775 ℃, and the heat preservation time is 2.5 h;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, heating to 1230 ℃, keeping the temperature for 11h, and then furnace-cooling to the forging temperature of 1155 ℃;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1155 ℃, the heat preservation time is 5 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a bar with the diameter of 200mm, and the pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2.5, and the total forging ratio is 11;
(5) ultra-fining treatment: performing superfine treatment on the obtained forging stock, normalizing and heating at 1047 ℃, preserving heat for 1.4h, and air-cooling to room temperature; annealing and heating at 853 ℃, preserving heat for 9.5h, cooling to 726 ℃ along with the furnace, preserving heat for 14 h, discharging from the furnace and air cooling after the furnace is cooled to be less than or equal to 500 ℃;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1070 ℃, preserving heat for 2.5 hours, and carrying out vacuum gas quenching to room temperature; tempering at 550 ℃ for 3.5h each time, carrying out tempering for three times, and cooling the sample to room temperature after each tempering.
The cold and hot dual-purpose steel phi 200mm bar produced according to the steps (1) to (5) is used as the steel for the thread rolling die, and after sampling at the core part, the thermal refining treatment is carried out according to the step (6), and the tempering hardness is 64.1 HRC; processed into standard Charpy impact test samples of 10mm multiplied by 55mm, the transverse impact energy is 8.2J, and the transverse and longitudinal impact energy ratio is 0.81.
Example 9
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an intermediate frequency furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode rod to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 760 ℃, and the heat preservation time is 4 hours;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, wherein the heating temperature is 1248 ℃, the heat preservation time is 10 hours, and then furnace cooling is carried out to the forging temperature 1160 ℃;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1160 ℃, the heat preservation time is 4.8 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a phi 200mm bar, and the pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2, and the total forging ratio is 10.5;
(5) ultra-fining treatment: carrying out superfine treatment on the obtained forged material, normalizing and heating at 1035 ℃, preserving heat for 1.2h, and air-cooling to room temperature; annealing and heating at 865 ℃, preserving heat for 9 hours, cooling to 732 ℃ along with the furnace, preserving heat for 13 hours, discharging from the furnace and air cooling after the furnace is cooled to be less than or equal to 500 ℃;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1088 ℃, preserving heat for 2 hours, and carrying out vacuum gas quenching to room temperature; tempering temperature is 568 ℃, tempering time is 3 hours each time, three times of tempering are carried out, and the sample is cooled to room temperature after each tempering.
The cold and hot dual-purpose steel phi 200mm bar produced according to the steps (1) to (5) is used as the steel for the thread rolling die, and after sampling at the core part, the thermal refining treatment is carried out according to the step (6), and the tempering hardness is 64.1 HRC; processed into standard Charpy impact test samples of 10mm multiplied by 55mm, the transverse impact energy is 8.4J, and the transverse and longitudinal impact energy ratio is 0.84.
Example 10
The chemical components and mass percentage contents of the steel used for the cold and hot dual-purpose thread rolling die in the embodiment are shown in table 1, and the preparation method comprises the following steps:
(1) smelting: smelting the ingredients by adopting an intermediate frequency furnace, refining, vacuum degassing and casting into an electrode bar;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode bar to prepare an electroslag ingot with the diameter of 300mm, and carrying out stress relief annealing on the obtained electroslag ingot, wherein the heating temperature is 755 ℃, and the heat preservation time is 3.5 h;
(3) high-temperature homogenization: carrying out high-temperature homogenization treatment on the electroslag ingot, wherein the heating temperature is 1245 ℃, the heat preservation time is 11 hours, and then furnace cooling is carried out until the forging temperature is 1168 ℃;
(4) forging: forging the electroslag ingot by adopting a three-pier three-drawing and multi-directional forging mode, wherein the forging heating temperature is 1168 ℃, the heat preservation time is 4.5 hours, the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, the forging stock is a phi 150mm bar, and the pit is cooled to be less than or equal to 300 ℃ after forging; upsetting deformation is carried out at the temperature of more than 1000 ℃, the first upsetting ratio is 2, and the total forging ratio is 11;
(5) ultra-fining treatment: carrying out superfine treatment on the obtained forged material, normalizing and heating at 1035 ℃, preserving heat for 1h, and cooling to room temperature; annealing at 866 deg.C, holding the temperature for 6.5h, cooling to 728 deg.C, holding the temperature for 10.5h, cooling to less than or equal to 500 deg.C, and air cooling;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1065 ℃, preserving heat for 2 hours, and carrying out vacuum gas quenching to room temperature; tempering at 550 ℃ for 3.5h each time, carrying out tempering for three times, and cooling the sample to room temperature after each tempering.
The hot and cold steel produced according to the steps (1) to (5) is used as the phi 150mm bar of the steel for the thread rolling die, and after sampling at the core part, the quenching and tempering treatment is carried out according to the step (6), and the tempering hardness is 62.9 HRC; processed into standard Charpy impact test samples of 10mm multiplied by 55mm, the transverse impact energy is 8.7J, and the transverse and longitudinal impact energy ratio is 0.82.
TABLE 1 chemical composition and mass% of steel for rolling die of each example
Figure DEST_PATH_IMAGE002
。

Claims (6)

1. The steel for the cold and hot combined rolling die is characterized by comprising the following chemical components in percentage by mass: 0.48 to 0.52%, Si: 0.85-1.2%, Mn: 0.3-0.5%, Cr: 4.0-4.5%, Mo: 1.6-2.0%, V: 0.85-1.2%, P is less than or equal to 0.015%, S is less than or equal to 0.01%, W: 0.3-0.5%, B: 0.002-0.005% of Fe and inevitable impurities as the rest; the carbon saturation Ac: 0.74-1.00.
2. The method for producing the steel for a hot and cold combined rolling die according to claim 1, comprising the steps of:
(1) smelting: smelting the ingredients, refining, vacuum degassing and casting into electrode bars;
(2) electroslag remelting: carrying out protective atmosphere electroslag remelting on the electrode bar to obtain an electroslag ingot, and carrying out stress relief annealing at the heating temperature of 750-780 ℃ for 2-4 h;
(3) high-temperature homogenization: performing high-temperature homogenization treatment on the electroslag ingot, wherein the heating temperature is 1220-1260 ℃, the heat preservation time is (0.3-0.4) × D hours, D is the diameter cm of the electroslag ingot, and then, furnace cooling is performed to the forging temperature of 1160 +/-10 ℃;
(4) forging: the initial forging temperature is 1100 ℃, the final forging temperature is 850 ℃, and the pit is cooled to be less than or equal to 300 ℃ after forging;
(5) ultra-fining treatment: carrying out superfine treatment on the obtained forging stock, normalizing and heating at 1040 +/-10 ℃, preserving heat for 0.05-0.1 multiplied by d hours, and air-cooling to room temperature; annealing and heating at 860 +/-10 ℃, preserving heat (0.4-0.5) x d hours, cooling to 730 +/-10 ℃ along with the furnace, preserving heat (0.6-0.75) x d hours, cooling to be less than or equal to 500 ℃ in the furnace, and then discharging and air cooling; d is the effective size cm of the forging material;
(6) quenching and tempering: quenching and tempering the superfine forged material, heating to 1060-1100 ℃, keeping the temperature for 0.1-0.15 x d hours, wherein d is the effective size cm of the forged material, and carrying out vacuum gas quenching to room temperature; tempering temperature is 560 +/-10 ℃, tempering time is 2-4 h each time, three times of tempering are carried out, and the sample is cooled to room temperature after each time of tempering.
3. The method for producing a steel for a hot and cold combined rolling die according to claim 2, wherein in the step (1), the melting is performed using an arc furnace or an intermediate frequency furnace.
4. The method for preparing the steel for the cold and hot combined rolling die according to claim 3, wherein in the step (4), the electroslag ingot is forged by adopting a three-pier three-drawing and multi-directional forging mode, the forging heating temperature is 1160 +/-10 ℃, and the temperature is kept for 4-6 hours.
5. The method for preparing the steel for a hot and cold rolling die according to claim 4, wherein in the step (4), upsetting deformation is performed at a temperature of 1000 ℃ or higher, the first upsetting ratio is not less than 2, and the total forging ratio is not less than 10.
6. The method for producing a steel for a hot and cold rolling die according to claims 2 to 5, wherein the steel for a hot and cold rolling die produced in the steps (1) to (5) is a bar having a diameter of 100 to 200mm, and is subjected to thermal refining in the step (6) after core sampling, and has a temper hardness of 62 to 65 HRC; the standard Charpy impact specimen with the thickness of 10mm multiplied by 55mm is processed, the transverse impact energy is more than or equal to 8J, and the transverse-longitudinal impact energy ratio is more than or equal to 0.8.
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CN114807545A (en) * 2022-04-24 2022-07-29 钢铁研究总院有限公司 Cold work die steel eutectic carbide refining heat treatment process
CN115652214A (en) * 2022-11-11 2023-01-31 中铁建华南建设(广州)高科技产业有限公司 Steel, preparation method thereof and hob ring
CN116426825A (en) * 2023-04-10 2023-07-14 常州天锐达模具有限公司 High-toughness die steel material, preparation method and die prepared by using same
CN117925970A (en) * 2024-03-22 2024-04-26 成都先进金属材料产业技术研究院股份有限公司 Preparation method of hot forging die steel

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CN114807545A (en) * 2022-04-24 2022-07-29 钢铁研究总院有限公司 Cold work die steel eutectic carbide refining heat treatment process
CN115652214A (en) * 2022-11-11 2023-01-31 中铁建华南建设(广州)高科技产业有限公司 Steel, preparation method thereof and hob ring
CN115652214B (en) * 2022-11-11 2023-11-03 中铁建华南建设(广州)高科技产业有限公司 Steel and preparation method thereof, hob ring
CN116426825A (en) * 2023-04-10 2023-07-14 常州天锐达模具有限公司 High-toughness die steel material, preparation method and die prepared by using same
CN116426825B (en) * 2023-04-10 2024-07-26 常州天锐达模具有限公司 High-toughness die steel material, preparation method and die prepared by using same
CN117925970A (en) * 2024-03-22 2024-04-26 成都先进金属材料产业技术研究院股份有限公司 Preparation method of hot forging die steel

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