High-strength and high-plasticity medium alloy steel material and high-entropy and high-plasticizing preparation method thereof

Abstract

The invention discloses a high-strength and high-plasticity medium alloy steel material and a high-entropy and high-plasticizing method thereof, and belongs to the technical field of alloy steel preparation. Carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high-entropy alloy particles are used as raw materials, two-step smelting is carried out, homogeneous heat treatment is carried out, multiple cold rolling and heat treatment are carried out, and the high-strength and high-plasticity medium alloy steel material is obtained. And finally, the high-strength plastic medium alloy steel material is obtained. The method has the advantages of high component control precision, high process stability and high repeatability, and can realize the high-strength and high-plasticity performance of the medium alloy steel material. According to the medium alloy steel material prepared through the method, the high-entropy alloy serves as a reinforcing phase, the tensile yield strength is larger than or equal to 1.1 GPa, the tensile strength is larger than or equal to 1.3 GPa, the tensile deformation rate is larger than or equal to 37%, and the tensile yield strength at the temperature of 600 DEG C is larger than or equal to 750 MPa.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy steel preparation, and specifically relates to a high-strength and medium-plastic alloy steel material and a high-entropy and strong-plastic preparation method thereof. Background Art

[0002] In today's context of accelerating global industrialization, the importance of materials science as the cornerstone of modern industrial development is becoming increasingly prominent. In particular, in many key areas such as machinery manufacturing, aerospace, automobile manufacturing, water conservancy projects, and agricultural production, the demand for high-performance materials is becoming increasingly urgent. Alloy steel, as a type of material with multiple excellent properties such as high strength, wear resistance, corrosion resistance, and high temperature resistance, has become the first choice for many high-end equipment manufacturers. With the advancement of science and technology and industrial upgrading, the machinery manufacturing industry is developing in a more efficient, more precise, and more environmentally friendly direction, which puts higher requirements on the performance of alloy steel materials, especially in the balance between strength and plasticity, which has become a key factor restricting its further widespread application.

[0003] In order to meet this demand, researchers are constantly exploring and optimizing the production process and composition design of alloy steel. Traditional carbon steel, as the basic material of alloy steel, has good plastic processing properties, but its strength is relatively low and it is difficult to meet the needs of high-strength application scenarios. Therefore, various types of alloy steels are formed by adding alloy elements such as chromium, nickel, and titanium to carbon steel. These alloy elements can effectively improve the strength of the material while giving it specific functional properties, such as corrosion resistance and high temperature resistance. However, traditional alloying methods often face the contradiction between increased strength and decreased plasticity, the so-called "strength-plasticity inversion" problem, which limits the further improvement of alloy steel performance and the expansion of its application range.

[0004] Although significant progress has been made in the research and development of alloy steels in recent years, how to effectively improve its plasticity while maintaining or improving its strength remains a major problem in the field of materials science. Traditional alloy design concepts and preparation processes are difficult to fundamentally solve this problem. As an emerging material design concept, high entropy alloys introduce a variety of main elements to form a highly disordered lattice structure, showing unique physical, chemical and mechanical properties, including high strength, high hardness and good toughness. However, integrating the concept of high entropy alloys into the production of alloy steels to achieve complementary advantages of both properties, especially in the simultaneous improvement of strength and plasticity, still faces many technical challenges, such as composition design, smelting process, optimization of heat treatment system and precise control of microstructure. Therefore, exploring an innovative alloy design and preparation technology to overcome the limitations of existing alloy steels in the balance between strength and plasticity has become an important direction of current materials science research. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a high-strength and plastic medium alloy steel material and a high entropy and strong plastic preparation method thereof, so as to solve the technical problem that the strength and plasticity of common alloy steel materials are in an inverted relationship.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention discloses a high entropy and strong plasticization preparation method for a high-strength and medium-plastic alloy steel material, comprising the following steps: Using carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles as raw materials, two-step smelting is first carried out, then homogenization heat treatment is carried out, and then multiple cold rolling and heat treatment are carried out to finally obtain high-strength and plastic medium alloy steel materials.

[0007] Preferably, the mass percentage of carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles is (92-94.5):(5.5-8).

[0008] Preferably, the mass percentage of carbon in the carbon steel alloy particles is 0.67% to 0.98%; the carbon steel alloy particles are nearly spherical or ellipsoidal, and the average particle size is 2.3 to 4.4 mm; In the cobalt-nickel-tungsten-molybdenum high entropy alloy particles, the mass percentages of cobalt, nickel, tungsten and molybdenum atoms are (42~45):(42~45):(5~8):(5~8).

[0009] Preferably, the conditions for the two-step smelting include: first, melting the carbon steel alloy particles into a uniform liquid in a vacuum arc melting furnace at a current of 62 to 67 amperes, maintaining for 90 to 110 seconds, and smelting 3 to 4 times; then, adding cobalt-nickel-tungsten-molybdenum high entropy alloy particles to the crucible according to mass percentage, increasing the smelting current to 71 to 75 amperes, maintaining for 45 to 57 seconds, and smelting 2 to 3 times.

[0010] Preferably, the temperature of the homogenization heat treatment is 1340-1390° C., and the holding time is 80-90 minutes.

[0011] Preferably, the conditions of multiple cold rolling and heat treatment include: taking the initial billet thickness as a reference, sequentially performing the first rolling and the first heat treatment; the second rolling and the second heat treatment; the third rolling and the third heat treatment.

[0012] Further preferably, the first rolling reduction is 43% to 48% of the initial billet thickness; the first rolling reduction is unidirectional rolling; the temperature of the first heat treatment is 1180 to 1230° C., and the time is 24 to 28 minutes.

[0013] Further preferably, the second rolling reduction is 16% to 20% of the initial billet thickness; the second rolling reduction is bidirectional rolling, and the rolling reduction is evenly divided; the temperature of the second heat treatment is 1050 to 1070° C., and the time is 16 to 18 minutes.

[0014] Further preferably, the third rolling reduction is 12% to 17% of the initial billet thickness; the third rolling reduction is bidirectional rolling, and the rolling reduction is equally divided; the temperature of the third heat treatment is 990 to 1030° C., and the time is 7 to 11 minutes.

[0015] The present invention also discloses a high-strength plastic medium alloy steel material, which is prepared by the high entropy and strong plasticization preparation method of the high-strength plastic medium alloy steel material. The high-strength plastic medium alloy steel material uses a high entropy alloy as a reinforcing phase, has a tensile yield strength ≥1.1GPa, a tensile strength ≥1.3GPa, a tensile deformation rate ≥37%, and a tensile yield strength at 600°C ≥750MPa.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention first uses carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles as raw materials, performs two-step smelting to obtain a cast alloy steel billet containing a high entropy reinforcement phase, then performs homogenization heat treatment on the cast alloy steel billet containing the high entropy reinforcement phase, and then performs multiple cold rolling and heat treatment; wherein the cobalt-nickel-tungsten-molybdenum high entropy alloy is a single-phase FCC structure, and has excellent strength and plasticity, and is used as a reinforcement phase for high-strength and high-plastic medium alloy steel; the two-step smelting technology can, on the one hand, maintain the uniformity and density of the carbon steel matrix phase, and on the other hand, effectively control the dispersion degree of the reinforcement phase in the matrix and the solid solution reaction process between the matrix / reinforcement phase by post-adding the reinforcement phase; the multiple cold rolling and heat treatment technology can not only increase the deformation of the cast billet, reduce the grain size, and improve the strength, but also adjust the arrangement state of the reinforcement phase to achieve high strength and high plasticity of the medium alloy steel. The high-strength plastic medium alloy steel material prepared by the invention uses high entropy alloy as a reinforcement phase, has a tensile yield strength of ≥1.1 GPa, a tensile strength of ≥1.3 GPa, a tensile deformation rate of ≥37%, and a tensile yield strength of ≥750 MPa at 600°C.

[0017] Further, in the process of preparing high-strength and plastic medium alloy steel, the present invention aims at the inversion problem of strength and plasticity of commonly used alloy steel materials, and studies the relationship between high-entropy alloy reinforcement phase components, matrix and reinforcement phase mass ratio, two-step smelting process, homogenization heat treatment process, multiple cold rolling and heat treatment processes and medium alloy steel strength and plasticity through overall high entropy, two-step smelting, homogenization heat treatment, multiple cold rolling and heat treatment processes, that is: for medium alloy steel, the best high entropy alloy reinforcement phase components, matrix and reinforcement phase mass ratio, two-step smelting process, homogenization heat treatment process and multiple cold rolling and heat treatment processes that maintain high strength and high plasticity. This method has high composition control accuracy, strong process stability and repeatability, and can achieve high strength and high plasticity of medium alloy steel.

[0018] Furthermore, the mass percentage of carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles is (92-94.5): (5.5-8). This ensures that carbon steel is the dominant matrix, while cobalt-nickel-tungsten-molybdenum high entropy alloy can be fully dispersed as a reinforcing phase and play its strengthening role. By precisely controlling the ratio of the two raw materials, the microstructure and mechanical properties of the alloy can be optimized, achieving a good balance between strength and plasticity.

[0019] Furthermore, in carbon steel alloy particles, the mass percentage of carbon is 0.67%~0.98%; carbon steel alloy particles are nearly spherical or ellipsoidal, with an average particle size of 2.3~4.4 mm; carbon is one of the main strengthening elements in steel materials, and its content directly affects the hardness and strength of steel. Adjusting the carbon content within this range can accurately control the mechanical properties of carbon steel, providing a good foundation for subsequent processing and heat treatment. Appropriate particle shape and particle size help to improve the uniformity of the smelting process and reduce smelting time and energy consumption. At the same time, uniform particle size distribution also helps to obtain a denser cast body and improve the overall performance of the material.

[0020] The mass percentages of cobalt, nickel, tungsten and molybdenum atoms in the cobalt-nickel-tungsten-molybdenum high entropy alloy particles are (42-45): (42-45): (5-8): (5-8). This ensures the single-phase FCC structure of the high entropy alloy, giving it excellent strength and plasticity. By precisely controlling the content of each element, the microstructure and mechanical properties of the high entropy alloy can be optimized, thereby improving its strengthening effect in the carbon steel matrix.

[0021] Furthermore, the conditions for the two-step smelting include: first, the carbon steel alloy particles are melted into a uniform liquid state in a vacuum arc melting furnace at a current of 62 to 67 amperes, maintained for 90 to 110 seconds, and smelted 3 to 4 times; then, cobalt-nickel-tungsten-molybdenum high entropy alloy particles are added to the crucible according to the mass percentage, the smelting current is increased to 71 to 75 amperes, maintained for 45 to 57 seconds, and smelted 2 to 3 times. The smelting process of carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles can be controlled separately to ensure the uniformity and density of the two during the smelting process. By precisely controlling parameters such as the smelting current, time, and number of times, the microstructure and mechanical properties of the alloy can be further optimized.

[0022] Furthermore, the temperature of the homogenization heat treatment is 1340~1390℃, and the holding time is 80~90 minutes. It helps to eliminate the internal stress and structural inhomogeneity in the cast body and improve the overall performance of the material. Heat treatment within this temperature range can ensure the full diffusion and uniform distribution of alloy elements, providing a good foundation for subsequent cold rolling and heat treatment.

[0023] Furthermore, the conditions of multiple cold rolling and heat treatment include: taking the initial billet thickness as the benchmark, first rolling, first heat treatment; second rolling, second heat treatment; third rolling, third heat treatment. Multiple cold rolling and heat treatment technology can significantly refine the grains and improve the strength and plasticity of the material. By accurately controlling the rolling amount, rolling method and heat treatment parameters, the microstructure and mechanical properties of the alloy can be further optimized to achieve high strength and high plasticity of medium alloy steel.

[0024] Furthermore, the first rolling amount is 43% to 48% of the initial billet thickness; the first rolling is unidirectional rolling; the temperature of the first heat treatment is 1180 to 1230 ° C, and the time is 24 to 28 minutes. The second rolling amount is 16% to 20% of the initial billet thickness; the second rolling is bidirectional rolling, and the rolling amount is evenly divided; the temperature of the second heat treatment is 1050 to 1070 ° C, and the time is 16 to 18 minutes. The third rolling amount is 12% to 17% of the initial billet thickness; the third rolling is bidirectional rolling, and the rolling amount is evenly divided; the temperature of the third heat treatment is 990 to 1030 ° C, and the time is 7 to 11 minutes. By gradually increasing the rolling amount and adjusting the rolling method, the grains can be gradually refined and the arrangement state of the reinforcement phase can be optimized. At the same time, appropriate heat treatment after each rolling can further eliminate internal stress and structural inhomogeneity and improve the overall performance of the material.

[0025] The present invention also discloses a high-strength plastic alloy steel material, which is prepared by the high entropy and strong plastic preparation method of the high-strength plastic alloy steel material, and has excellent mechanical properties and high-temperature stability. The high-strength plastic alloy steel material uses a high entropy alloy as a reinforcement phase, and has a tensile yield strength of ≥1.1GPa, a tensile strength of ≥1.3GPa, a tensile deformation rate of ≥37%, and a tensile yield strength of ≥750MPa at 600°C. It can be widely used in fields requiring high strength, high plasticity and high-temperature stability, such as aerospace, automobile manufacturing, energy engineering, etc. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the present invention, unless otherwise specified, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0028] In the present invention, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0029] In the present invention, unless otherwise specified, percentage (%) or part refers to the weight percentage or weight part relative to the composition.

[0030] In the present invention, unless otherwise specified, the components or preferred components involved can be combined with each other to form a new technical solution.

[0031] In the present invention, unless otherwise specified, the numerical range "a~b" represents an abbreviation of any real number combination between a and b, where a and b are real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been listed in this document, and "6~22" is just an abbreviation of these numerical combinations.

[0032] The “range” disclosed in the present invention is in the form of a lower limit and an upper limit, which can be one or more lower limits, and one or more upper limits, respectively.

[0033] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0034] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the sequence. Preferably, the reaction method herein is carried out sequentially.

[0035] Unless otherwise specified, the professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content may also be applied to the present invention.

[0036] The present invention discloses a method for high entropy and strong plasticization of a high-strength medium-plastic alloy steel material, comprising the following steps: 1) Carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are used as raw materials. The carbon mass percentage of the carbon steel alloy particles is 0.67%-0.98%, the alloy particles are nearly spherical or ellipsoidal, and the average particle size is 2.3-4.4 mm; the atomic percentages of cobalt, nickel, tungsten, and molybdenum in the cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 42-45:42-45:5-8:5-8; the mass percentages of carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 92-94.5:5.5-8. First, the carbon steel alloy particles are melted into a uniform liquid in a vacuum arc melting furnace at a current of 62-67 amperes, maintained for 90-110 seconds, and melted 3-4 times, and then cobalt-nickel-tungsten-molybdenum high entropy alloy particles are added to the crucible according to the mass percentage, the melting current is increased to 71-75 amperes, maintained for 45-57 seconds, and melted 2-3 times to obtain a cast alloy steel billet containing a high entropy enhanced phase; 2) The as-cast alloy steel billet containing high entropy enhanced phase is subjected to homogenization heat treatment at 1340~1390℃ for 80~90 minutes, and then multiple cold rolling and heat treatment are carried out based on the initial billet thickness. The first rolling reduction is 43%~48%, unidirectional rolling, the first heat treatment temperature and time are 1180~1230℃ and 24~28 minutes respectively, the second rolling reduction is 16%~20%, bidirectional rolling, the rolling reduction is evenly divided, the second heat treatment temperature and time are 1050~1070℃ and 16~18 minutes respectively, the third rolling reduction is 12%~17%, bidirectional rolling, the rolling reduction is evenly divided, the third heat treatment temperature and time are 990~1030℃ and 7~11 minutes respectively, and finally a high-strength and plastic medium alloy steel material is obtained.

[0037] The present invention uses high entropy alloy as the strengthening phase, and realizes the simultaneous improvement of the strength and plasticity of the medium alloy steel material through two-step melting, averaging treatment, multiple cold rolling and heat treatment processes. It has high composition control precision, strong process stability and repeatability, and can achieve high strength and high plasticity of the medium alloy steel material. It solves the technical problem that the strength and plasticity of commonly used alloy steel materials are in an inverted relationship. The prepared medium alloy steel material uses high entropy alloy as the strengthening phase, with a tensile yield strength ≥1.1GPa, a tensile strength ≥1.3GPa, a tensile deformation rate ≥37%, and a 600℃ tensile yield strength ≥750MPa.

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Usually, the components of the embodiments of the present invention can be arranged and designed by various different configurations. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0039] Example 1 A method for preparing a high-entropy and strong-plastic alloy steel material, comprising the following steps: 1) Carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are used as raw materials. The carbon mass percentage of the carbon steel alloy particles is 0.67%, the alloy particles are nearly spherical, and the average particle size is 2.3 mm; the atomic percentages of cobalt, nickel, tungsten, and molybdenum in the cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 42:42:8:8; the mass percentages of carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 92:8. First, the carbon steel alloy particles are melted into a uniform liquid in a vacuum arc melting furnace at a current of 62 amperes, maintained for 90 seconds, and melted three times. Then, cobalt-nickel-tungsten-molybdenum high entropy alloy particles are added to the crucible according to the mass percentage, and the melting current is increased to 71 amperes, maintained for 45 seconds, and melted twice to obtain a cast alloy steel billet containing a high entropy enhanced phase; 2) The as-cast alloy steel billet containing high entropy enhanced phase was subjected to homogenization heat treatment at 1340°C for 80 minutes, and then subjected to multiple cold rolling and heat treatment based on the initial billet thickness. The first rolling reduction was 43%, unidirectional rolling, the first heat treatment temperature and time were 1180°C and 24 minutes, respectively. The second rolling reduction was 16%, bidirectional rolling, the rolling reduction was evenly divided, the second heat treatment temperature and time were 1050°C and 16 minutes, respectively. The third rolling reduction was 12%, bidirectional rolling, the rolling reduction was evenly divided, the third heat treatment temperature and time were 990°C and 7 minutes, respectively, to finally obtain a high-strength and plastic medium alloy steel material.

[0040] Example 2 A method for preparing a high-entropy and strong-plastic alloy steel material, comprising the following steps: 1) Carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are used as raw materials. The carbon mass percentage of the carbon steel alloy particles is 0.98%, the alloy particles are ellipsoidal, and the average particle size is 4.4 mm; the atomic percentages of cobalt, nickel, tungsten, and molybdenum in the cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 45:45:5:5; the mass percentages of carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 94.5:5. First, the carbon steel alloy particles are melted into a uniform liquid in a vacuum arc melting furnace at a current of 67 amperes, maintained for 110 seconds, and melted 4 times. Then, cobalt-nickel-tungsten-molybdenum high entropy alloy particles are added to the crucible according to the mass percentage, and the melting current is increased to 75 amperes, maintained for 57 seconds, and melted 3 times to obtain a cast alloy steel billet containing a high entropy enhanced phase; 2) The as-cast alloy steel billet containing high entropy enhanced phase was subjected to homogenization heat treatment at 1390°C for 80 minutes, and then subjected to multiple cold rolling and heat treatment based on the initial billet thickness. The first rolling reduction was 48%, unidirectional rolling, the first heat treatment temperature and time were 1180°C and 28 minutes, respectively. The second rolling reduction was 16%, bidirectional rolling, the rolling reduction was evenly divided, the second heat treatment temperature and time were 1070°C and 18 minutes, respectively. The third rolling reduction was 12%, bidirectional rolling, the rolling reduction was evenly divided, the third heat treatment temperature and time were 1030°C and 11 minutes, respectively, to finally obtain a high-strength and plastic medium alloy steel material.

[0041] Example 3 A method for preparing a high-entropy and strong-plastic alloy steel material, comprising the following steps: 1) Carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are used as raw materials. The carbon mass percentage of the carbon steel alloy particles is 0.79%, the alloy particles are nearly spherical, and the average particle size is 2.8 mm; the atomic percentages of cobalt, nickel, tungsten, and molybdenum in the cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 44:43:6:7; the mass percentage of carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles is 93:7. First, the carbon steel alloy particles are melted into a uniform liquid in a vacuum arc melting furnace at a current of 65 amperes, maintained for 100 seconds, and melted three times. Then, cobalt-nickel-tungsten-molybdenum high entropy alloy particles are added to the crucible according to the mass percentage, and the melting current is increased to 72 amperes, maintained for 52 seconds, and melted twice to obtain a cast alloy steel billet containing a high entropy enhanced phase; 2) The as-cast alloy steel billet containing high entropy enhanced phase was subjected to homogenization heat treatment at 1360°C for 85 minutes, and then subjected to multiple cold rolling and heat treatment based on the initial billet thickness. The first rolling reduction was 45%, unidirectional rolling, the first heat treatment temperature and time were 1190°C and 26 minutes, respectively. The second rolling reduction was 18%, bidirectional rolling, the rolling reduction was evenly divided, the second heat treatment temperature and time were 1060°C and 17 minutes, respectively. The third rolling reduction was 14%, bidirectional rolling, the rolling reduction was evenly divided, the third heat treatment temperature and time were 1030°C and 9 minutes, respectively, to finally obtain a high-strength and plastic medium alloy steel material.

[0042] Example 4 A method for preparing a high-entropy and strong-plastic alloy steel material, comprising the following steps: 1) Carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are used as raw materials. The carbon mass percentage of the carbon steel alloy particles is 0.84%, the alloy particles are ellipsoidal, and the average particle size is 3.5 mm; the atomic percentages of cobalt, nickel, tungsten, and molybdenum in the cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 43:44:7:6; the mass percentages of carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 93:7. First, the carbon steel alloy particles are melted into a uniform liquid in a vacuum arc melting furnace at a current of 66 amperes, maintained for 110 seconds, and melted 4 times. Then, cobalt-nickel-tungsten-molybdenum high entropy alloy particles are added to the crucible according to the mass percentage, and the melting current is increased to 72 amperes, maintained for 57 seconds, and melted 3 times to obtain a cast alloy steel billet containing a high entropy enhanced phase; 2) The as-cast alloy steel billet containing high entropy enhanced phase was subjected to homogenization heat treatment at 1350°C for 80 minutes, and then subjected to multiple cold rolling and heat treatment based on the initial billet thickness. The first rolling reduction was 43%, unidirectional rolling, the first heat treatment temperature and time were 1180°C and 27 minutes, respectively. The second rolling reduction was 19%, bidirectional rolling, the rolling reduction was evenly divided, the second heat treatment temperature and time were 1050°C and 16 minutes, respectively. The third rolling reduction was 17%, bidirectional rolling, the rolling reduction was evenly divided, the third heat treatment temperature and time were 1030°C and 11 minutes, respectively, to finally obtain a high-strength and plastic medium alloy steel material.

[0043] Example 5 A method for preparing a high-entropy and strong-plastic alloy steel material, comprising the following steps: 1) Carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are used as raw materials. The carbon mass percentage of the carbon steel alloy particles is 0.84%, the alloy particles are ellipsoidal, and the average particle size is 3.5 mm; the atomic percentages of cobalt, nickel, tungsten, and molybdenum in the cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 43:44:7:6; the mass percentages of carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles are 93:7. First, the carbon steel alloy particles are melted into a uniform liquid in a vacuum arc melting furnace at a current of 66 amperes, maintained for 110 seconds, and melted 4 times. Then, cobalt-nickel-tungsten-molybdenum high entropy alloy particles are added to the crucible according to the mass percentage, and the melting current is increased to 72 amperes, maintained for 57 seconds, and melted 3 times to obtain a cast alloy steel billet containing a high entropy enhanced phase; 2) The as-cast alloy steel billet containing high entropy enhanced phase was subjected to homogenization heat treatment at 1350°C for 90 minutes, and then subjected to multiple cold rolling and heat treatment based on the initial billet thickness. The first rolling reduction was 43%, unidirectional rolling, the first heat treatment temperature and time were 1230°C and 27 minutes, respectively. The second rolling reduction was 20%, bidirectional rolling, the rolling reduction was evenly divided, the second heat treatment temperature and time were 1050°C and 16 minutes, respectively. The third rolling reduction was 17%, bidirectional rolling, the rolling reduction was evenly divided, the third heat treatment temperature and time were 1030°C and 11 minutes, respectively, to finally obtain a high-strength and plastic medium alloy steel material.

[0044] Table 1 Characteristic parameters of high strength and plastic medium alloy steel materials prepared in Examples 1 to 4

[0045] Table 1 shows the characteristic parameters of the high-strength plastic medium alloy steel materials prepared in Examples 1 to 4. It can be concluded from the above table that the high-strength plastic medium alloy steel materials prepared by the present invention use high entropy alloy as the reinforcement phase, and have a tensile yield strength ≥1.1 GPa, a tensile strength ≥1.3 GPa, a tensile deformation rate ≥37%, and a 600°C tensile yield strength ≥750 MPa.

[0046] In summary, the high entropy and strong plastic preparation method of a high-strength plastic medium alloy steel material of the present invention adopts cobalt-nickel-tungsten-molybdenum high entropy alloy as a reinforcing phase, and combines two-step smelting, homogenization heat treatment, and multiple cold rolling and heat treatment processes. The high-strength plastic medium alloy steel material prepared by the method has excellent mechanical properties. Specifically, the tensile yield strength is ≥1.1GPa, the tensile strength is ≥1.3GPa, the tensile deformation rate is ≥37%, and the tensile yield strength can still be maintained at ≥750MPa even at a high temperature of 600°C. These performance indicators far exceed traditional alloy steels and meet the comprehensive requirements of high strength, high plasticity and high temperature stability of materials. The two-step smelting technology effectively maintains the uniformity and density of the carbon steel matrix phase, and at the same time, by adding the reinforcing phase later, the dispersion degree of the reinforcing phase in the matrix is ​​accurately controlled, and the performance degradation caused by excessive solid solution reaction is avoided. Multiple cold rolling and heat treatment further refine the grains and adjust the arrangement state of the reinforcing phase, thereby achieving high strength and high plasticity of the medium alloy steel. Aiming at the common problem of strength and plasticity being difficult to balance in traditional alloy steels, this method has successfully achieved the simultaneous improvement of strength and plasticity through overall high entropy design combined with fine process control. This not only broadens the application scope of alloy steels, but also provides new ideas for the high-strength and high-plasticity design of other metal materials. This preparation method has the characteristics of high composition control precision, process stability and strong repeatability. By strictly controlling the process parameters of each step, the performance of each batch of products can be ensured to be stable and consistent, meeting the needs of large-scale industrial production. The research and application of this method not only promotes the development of high-strength and high-plastic alloy steel materials, but also provides new perspectives and ideas for the research in cutting-edge fields such as high entropy alloys and metal-based composites. It shows that through the combination of material design and process innovation, it is possible to break through the performance limits of traditional materials and develop new materials with higher performance.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing high-entropy and strong plasticization high-strength medium-plastic alloy steel material, characterized in that: The following steps are involved: Using carbon steel alloy particles and cobalt-nickel-tungsten-molybdenum high entropy alloy particles as raw materials, two-step smelting is first carried out, then homogenization heat treatment is carried out, and then multiple cold rolling and heat treatment are carried out to finally obtain high-strength and plastic medium alloy steel materials.

2. The high entropy and strong plasticization preparation method of high-strength and medium-plastic alloy steel material according to claim 1, characterized in that: The mass percentage of the carbon steel alloy particles and the cobalt-nickel-tungsten-molybdenum high entropy alloy particles is (92-94.5): (5.5-8).

3. The high entropy and strong plasticization preparation method of high-strength and medium-plastic alloy steel material according to claim 1, characterized in that: The mass percentage of carbon in the carbon steel alloy particles is 0.67% to 0.98%; the carbon steel alloy particles are nearly spherical or ellipsoidal, and the average particle size is 2.3 to 4.4 mm; In the cobalt-nickel-tungsten-molybdenum high entropy alloy particles, the mass percentages of cobalt, nickel, tungsten and molybdenum atoms are (42-45): (42-45): (5-8): (5-8).

4. The high entropy and strong plasticization preparation method of high-strength and medium-plastic alloy steel material according to claim 1, characterized in that: The conditions of the two-step smelting include: first, melting the carbon steel alloy particles into a uniform liquid state in a vacuum arc melting furnace at a current of 62 to 67 amperes, maintaining for 90 to 110 seconds, and smelting 3 to 4 times; then, adding cobalt-nickel-tungsten-molybdenum high entropy alloy particles into the crucible according to mass percentage, increasing the smelting current to 71 to 75 amperes, maintaining for 45 to 57 seconds, and smelting 2 to 3 times.

5. The high entropy and strong plasticization preparation method of high-strength and medium-plastic alloy steel material according to claim 1, characterized in that: The temperature of the homogenization heat treatment is 1340-1390° C., and the insulation time is 80-90 minutes.

6. The high entropy and strong plasticization preparation method of high-strength and medium-plastic alloy steel material according to claim 1, characterized in that: The conditions of the multiple cold rolling and heat treatment include: taking the initial billet thickness as a reference, sequentially performing the first rolling and the first heat treatment; the second rolling and the second heat treatment; the third rolling and the third heat treatment.

7. The high entropy and strong plasticization preparation method of high-strength and medium-plastic alloy steel material according to claim 6, characterized in that: The first rolling reduction amount is 43% to 48% of the initial billet thickness; the first rolling reduction is unidirectional rolling; the temperature of the first heat treatment is 1180 to 1230° C., and the time is 24 to 28 minutes.

8. The high entropy and strong plasticization preparation method of high-strength and medium-plastic alloy steel material according to claim 6, characterized in that: The second rolling reduction is 16% to 20% of the initial billet thickness; the second rolling reduction is bidirectional rolling, and the rolling reduction is equally divided; the temperature of the second heat treatment is 1050 to 1070° C., and the time is 16 to 18 minutes.

9. The high entropy and strong plasticization preparation method of high-strength and medium-plastic alloy steel material according to claim 6, characterized in that: The third rolling reduction is 12% to 17% of the initial billet thickness; the third rolling reduction is bidirectional rolling, and the rolling reduction is equally divided; the temperature of the third heat treatment is 990 to 1030° C., and the time is 7 to 11 minutes.

10. A high-strength plastic medium alloy steel material, characterized in that: The high-strength plastic alloy steel material is prepared by the high entropy and strong plasticization preparation method of any one of claims 1 to 9, wherein the high-strength plastic alloy steel material uses a high entropy alloy as a reinforcing phase, has a tensile yield strength ≥1.1GPa, a tensile strength ≥1.3GPa, a tensile deformation rate ≥37%, and a 600°C tensile yield strength ≥750MPa.

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