Method for reducing precipitation temperature of nano copper-rich phase and application thereof

Abstract

The invention discloses a method for reducing the precipitation temperature of a nano copper-rich phase and application of the method, and relates to the technical field of metal material precipitation strengthening. Rare earth metal elements are added into the copper-containing steel, and the precipitation temperature of a nano copper-rich phase is reduced to be not higher than 480 DEG C by regulating and controlling the copper precipitation behavior through the rare earth metal elements. According to the method, based on a 9R-Cu phase low-temperature precipitation mechanism of rare earth element micro regulation and control, the effective precipitation temperature of the 9R-Cu phase is reduced to 480 DEG C or below through the heterogeneous nucleation promotion effect of Ce atoms in the Cu precipitation process, so that it is guaranteed that a base material obtains the excellent strengthening effect, meanwhile, formation of a brittle phase on the interface of the composite material is avoided, and the service life of the composite material is prolonged. And coordination and unification of base material strengthening and interface stability are realized.

Description

Technical Field

[0001] This invention relates to the field of precipitation strengthening technology for metallic materials, and particularly to a method for reducing the precipitation temperature of nano-copper-rich phases. Background Technology

[0002] In extreme environments such as marine engineering and deep-sea development, novel materials with multiple properties, including high strength, corrosion resistance, resistance to hydrogen embrittlement, and resistance to microbial corrosion, are required. Layered metal composites are an ideal choice due to their ability to perform functional divisions; the substrate provides high strength and resistance to microbial corrosion, while the cladding provides resistance to hydrogen and strong corrosion. In the design of composite substrates, precipitation strengthening through the addition of Cu is an important technical approach to achieve both high strength and resistance to microbial corrosion.

[0003] Advantages and Temperature Bottlenecks of 9R-Cu Precipitation Strengthening. Among nano-copper-rich phases, the 9R-Cu phase exhibits optimal strengthening effects and resistance to microbial corrosion due to its unique crystal structure and coherent relationship with the matrix. Chinese Patent ZL2019105119128 discloses a nano-precipitation strengthening technology that demonstrates the ability of 9R-Cu precipitation to increase the yield strength of steel by 200-300 MPa while significantly improving its resistance to microbial corrosion. However, the effective precipitation temperature of the 9R-Cu phase in existing technologies is generally above 600℃. While this high temperature requirement is easily achieved for elemental materials, it has become a key technological bottleneck for composite material applications.

[0004] The precipitation temperature of the 9R-Cu phase above 600℃ has led to a series of technical challenges in the application of high-strength hydrogen-resistant composite board substrates:

[0005] First, during the manufacturing stage, heat treatment at temperatures above 600℃ causes severe interdiffusion of elements at the composite material interface, forming brittle intermetallic compounds such as Fe-Al, Fe-Ti, and Fe-Cr. Studies have shown that at temperatures of 600-650℃, the thickness of the brittle phase at the interface can reach 15-25 μm, leading to reduced interfacial peel strength and severely deteriorating the overall performance and service reliability of the composite material.

[0006] Secondly, in welding applications, the welding thermal cycle (peak temperature 1200-1400℃) causes the precipitated 9R-Cu phase in the heat-affected zone to completely dissolve again, reducing the strength of the weld area by about 200 MPa; the resistance to microbial corrosion also decreases significantly. To restore weld performance, post-weld heat treatment is necessary, but treatment temperatures above 600℃ will reactivate the interface embrittlement process, forming a vicious cycle of "weld performance recovery - interface performance deterioration".

[0007] Third, residual stress generated in composite materials during manufacturing and service requires stress relief treatment to ensure structural stability. For Cu-reinforced steel substrates that rely on nano-copper-rich phases for stress relaxation, the redistribution and growth of these phases are crucial stress relief mechanisms. However, the precipitation temperature of the traditional 9R-Cu phase, above 600℃, inevitably impairs interfacial properties during stress relief treatment, limiting the long-term service capability of composite materials under high-stress environments.

[0008] The fundamental reason for the aforementioned technical difficulties lies in the lack of effective means to control the precipitation temperature of the 9R-Cu phase in existing technologies. Traditional Cu precipitation strengthening techniques mainly rely on optimization from three aspects: Cu content, cooling rate, and aging process. However, regardless of the optimization strategy employed, it is difficult to break through the 600℃ temperature threshold and fundamentally change the precipitation temperature of the 9R-Cu phase; therefore, the contradiction between this and the interfacial stability of the composite material remains unresolved. Existing technologies can only compromise between "substrate strengthening effect" and "interfacial stability," failing to achieve a harmonious balance between the two.

[0009] While rare earth elements have applications in iron and steel metallurgy, they are mainly concentrated in traditional areas such as deoxidation and desulfurization. Current technology has limited understanding of the precipitation behavior regulated by rare earth elements, particularly the influence mechanism of Ce on the precipitation temperature of the 9R-Cu phase, which has not yet been systematically studied and applied. This presents an important technological opportunity to achieve low-temperature precipitation of the 9R-Cu phase through Ce regulation.

[0010] With the development of marine engineering towards the deep sea and the advancement of polar energy development, the demand for high-performance composite materials is becoming increasingly urgent. The existing technical dilemma of "high-temperature precipitation-interfacial damage" has become a key bottleneck restricting the engineering application of composite materials. There is an urgent need to develop a new technology that can reduce the precipitation temperature of the 9R-Cu phase to below 500℃, fundamentally resolving the technical contradiction between substrate strengthening and interfacial stability in composite materials, and providing reliable technical support for the application of high-strength antibacterial steel substrates in composite materials. Summary of the Invention

[0011] To address the technical problems of high-strength, hydrogen-resistant composite substrates, such as interface embrittlement, post-weld heat treatment difficulties, and stress relief damage caused by the excessively high precipitation temperature of the 9R-Cu phase (above 600℃), this invention provides a method for reducing the precipitation temperature of the nano-copper-rich phase and its application. Based on the low-temperature precipitation mechanism of the 9R-Cu phase under microscopic control by rare earth elements, and through the heterogeneous nucleation-promoting effect of Ce atoms during Cu precipitation, the effective precipitation temperature of the 9R-Cu phase is reduced to below 480℃. This ensures excellent strengthening of the substrate while avoiding the formation of brittle phases at the composite material interface, achieving a coordinated balance between substrate strengthening and interface stability. Specifically, this is achieved through the following techniques.

[0012] In a first aspect, the present invention provides a method for reducing the precipitation temperature of a nano-copper-rich phase by adding rare earth metal elements to the copper-containing steel, thereby reducing the precipitation temperature of the nano-copper-rich phase to no more than 480°C by regulating the copper precipitation behavior of the rare earth metal elements.

[0013] Furthermore, the proportion of 9R-Cu phase in the nano-copper-rich phase is 20-80%, and the precipitation temperature of the 9R-Cu phase is 420-480℃.

[0014] Furthermore, the content of the rare earth metal element in the copper-containing steel is 0.005-0.030 wt% by mass percentage.

[0015] Furthermore, the content of the rare earth metal elements in the copper-containing steel is 0.008-0.025 wt% by mass percentage.

[0016] Furthermore, the rare earth metal element is Ce.

[0017] Furthermore, rare earth metal elements are added to the molten steel to the target content, and the mixture is kept at a temperature not exceeding 480°C to achieve the precipitation of the nano-copper-rich phase.

[0018] Furthermore, rare earth metal elements are added to molten steel at 1550-1700℃ in the form of rare earth master alloys.

[0019] Furthermore, it is kept at a temperature of 420-480℃ for 0.2-3 hours.

[0020] The core technical idea of ​​this invention is based on the thermodynamic-kinetic dual regulation mechanism of rare earth elements (such as Ce) on the nucleation and growth process of copper-rich nanophases. Through in-depth research on the electronic structure characteristics of Ce atoms and their existence forms in steel matrices, it was found that Ce can significantly reduce the formation energy barrier of 9R-Cu precipitates through multiple mechanisms such as heterogeneous nucleation effect, elastic field modulation effect, and diffusion path optimization, thereby reducing its precipitation temperature from the traditional 600℃ to below 480℃.

[0021] Specifically, the heterogeneous nucleation mechanism involves rare earth elements (such as Ce) and their oxides, sulfides, and other compounds forming numerous heterogeneous nucleation sites within the steel matrix. These nucleation sites exhibit excellent lattice matching with the 9R-Cu phase, significantly lowering the critical energy barrier required for nucleation. Compared to homogeneous nucleation, the heterogeneous nucleation mechanism allows the 9R-Cu phase to precipitate at lower supersaturation conditions, resulting in a substantial reduction in precipitation temperature. Lattice matching calculations reveal a favorable lattice matching relationship between Ce oxide Ce₂O₃ and the 9R-Cu phase, with a mismatch degree of less than 5%, providing advantageous interfacial conditions for heterogeneous nucleation.

[0022] Elastic field modulation mechanism: The atomic radii of rare earth elements (such as Ce) differ significantly from those of Fe atoms, and their presence in the steel matrix generates local elastic distortion. This elastic distortion field interacts with the strain field of the nano-copper-rich phase, effectively reducing the elastic strain energy of the nano-copper-rich phase, making the precipitation process thermodynamically more favorable.

[0023] Diffusion path optimization mechanism: Atoms of rare earth elements (such as Ce) tend to combine with vacancies to form "rare earth atom-vacancy complexes." These complexes alter the diffusion path and rate of Cu atoms in the steel matrix. Although the migration barrier of Cu atoms is increased in some diffusion directions, in specific diffusion channels, the "rare earth atom-vacancy complexes" actually provide a more convenient diffusion path for Cu atoms, promoting short-range ordering of Cu and inhibiting long-range diffusion of Cu, thus lowering the precipitation temperature of 9R-Cu; at the same time, it inhibits the coarsening of 9R-Cu and the transformation to the FCC phase.

[0024] Phase stability regulation mechanism: The presence of rare earth element (such as Ce) atoms can selectively stabilize the 9R-Cu phase, giving it higher thermodynamic stability compared to other precipitated phases, thus ensuring that the 9R-Cu phase with the best strengthening effect is mainly formed during low-temperature precipitation.

[0025] In a second aspect, the present invention also provides a copper-containing steel material, which is prepared by any of the methods described above.

[0026] Furthermore, by mass percentage, the copper-containing steel contains 0.7-1.5% copper, 0.005-0.030% rare earth metals, 0.03-0.15% carbon, 0.5-1.5% manganese, and 0.1-0.6% silicon, with the balance being Fe and unavoidable impurities. The precipitation temperature of the nano-copper-rich phase in the copper-containing steel is 420-480℃.

[0027] Furthermore, by mass percentage, the copper-containing steel also includes one or more of the following: nickel 0.1-0.8%, titanium 0.005-0.05%, niobium 0.005-0.05%, and chromium 0.2-1.0%.

[0028] In a third aspect, the present invention also provides a low-temperature strengthening method for a composite material substrate, using the copper-containing steel prepared by any of the above methods as the substrate; the heat treatment temperature of the substrate is controlled at no more than 480°C, thereby achieving precipitation strengthening of the substrate while avoiding the formation of brittle phases at the interface;

[0029] Furthermore, the cladding material of the composite material is one or more of stainless steel, nickel-based alloy, and titanium alloy.

[0030] Compared with the prior art, the advantages of this invention are: by precisely controlling the precipitation behavior of Cu by rare earth elements such as Ce, this invention achieves technological breakthroughs and performance improvements at multiple levels, and has significant technical advantages and broad application prospects.

[0031] 1. Significantly reduced precipitation temperature: Compared with the aging temperature of 500-600℃ in Chinese Patent ZL2019105119128 and the treatment temperature of 550℃ in Japanese Patent JP6794479B2, the present invention reduces the precipitation temperature to below 480℃, a reduction of 100-150℃, fundamentally solving the contradiction between substrate strengthening and interface stability.

[0032] 2. Significantly Improved Interface Stability: This design avoids the interface embrittlement problems caused by the 680℃ high-temperature treatment in Chinese Patent ZL2015100024833 and the 640-680℃ treatment temperature in Chinese Patent ZL2020112698927. It not only improves the static mechanical properties of the composite material but also enhances its service performance under dynamic loads and fatigue conditions. This is particularly important for composite materials containing active metals such as pure Ti and Ti alloys.

[0033] 3. Excellent overall performance: The 9R-Cu precipitate not only provides a strengthening effect, but its unique crystal structure can also effectively hinder the penetration of corrosive media. The material's resistance to microbial corrosion is also significantly improved, and its resistance to typical marine microorganisms such as sulfate-reducing bacteria and hydrogen resistance are also improved.

[0034] 4. Significant Industrial Application Value: The substantial reduction in precipitation temperature decreases heat treatment energy consumption by 20-30%, generating considerable economic value in large-scale industrial production. The benefits of process simplification are equally significant, reducing overall manufacturing costs by 10-15%, providing an economically feasible technical solution for the engineering application of high-performance composite materials. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the heat treatment process for copper-containing steel substrates.

[0036] Figure 2 Metallographic image of 9R-Cu substrate containing 1.3Ce copper after heat treatment. Detailed Implementation

[0037] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] In some embodiments of the present invention, a method for reducing the precipitation temperature of nano-copper-rich phase is provided, wherein rare earth metal elements are added to the copper-containing steel, and the precipitation temperature of nano-copper-rich phase is reduced to no more than 480°C by regulating the copper precipitation behavior by the rare earth metal elements.

[0039] Optionally, in the above method, the proportion of 9R-Cu phase in the nano-copper-rich phase is 20-80%, and the precipitation temperature of the 9R-Cu phase is 420-480℃.

[0040] Optionally, in the above method, the content of rare earth metal elements in the copper-containing steel is 0.005-0.030 wt% by mass percentage.

[0041] Specifically, in the above method, the content of rare earth metal elements in the copper-containing steel is 0.008-0.025 wt% by mass percentage.

[0042] Optionally, in the above method, the rare earth metal element is Ce.

[0043] Optionally, in the above method, rare earth metal elements are added to the molten steel to the target content, and the mixture is kept at a temperature not exceeding 480°C to achieve the precipitation of nano-copper-rich phase.

[0044] Preferably, rare earth metal elements are added to molten steel at 1550-1700°C in the form of rare earth intermediate alloys.

[0045] Preferably, the temperature is kept at 420-480℃ for 0.2-3 hours.

[0046] In other embodiments of the present invention, the copper-containing steel prepared by the above method contains, by mass percentage, 0.7-1.5% copper, 0.005-0.030% rare earth metal elements, 0.03-0.15% carbon, 0.5-1.5% manganese, 0.1-0.6% silicon, with the balance being Fe and unavoidable impurities. The precipitation temperature of the nano-copper-rich phase in the copper-containing steel is 420-480℃.

[0047] Optionally, by mass percentage, the copper-containing steel may also include one or more of the following: nickel 0.1-0.8%, titanium 0.005-0.05%, niobium 0.005-0.05%, and chromium 0.2-1.0%.

[0048] The copper-containing steel provided by this invention adopts a multi-element alloy system, and the alloy composition includes:

[0049] The main strengthening element Cu is controlled within the range of 0.80-1.20%. This content range takes into account the successful experience of existing technologies and the technical features of this invention. Compared with the 1%-2% Cu content in the existing technology CN201910511912.8, this invention, through the regulation of Ce, can achieve the same or even better strengthening effect at a lower Cu content, while reducing the tendency for hot brittleness and cost.

[0050] Synergistic strengthening element Ni: The content is set at 0.15-0.60%. Ni plays an important synergistic role in the Cu precipitation strengthening system. It can form co-precipitates with Cu, improve the thermal stability of the nano-copper-rich phase, and effectively suppress the hot brittleness tendency of Cu, thereby improving the hot working performance of the material.

[0051] The rare earth element Ce is precisely controlled within the range of 0.008-0.025%. This content range is the core technical parameter of this invention, determined through extensive theoretical calculations and experimental verification. Too low a Ce content cannot provide sufficient heterogeneous nucleation sites and elastic field modulation effects; too high a Ce content may lead to the formation of rare earth inclusions, which would adversely affect the material properties.

[0052] Matrix element design follows the principle of low carbon and medium manganese. The carbon content is controlled at 0.06-0.12%, ensuring matrix strength while avoiding the adverse effects of excessive carbon content on toughness. The manganese (Mn) content is set at 0.70-1.10%, primarily serving to strengthen through solid solution and improve hardenability. The silicon (Si) content is controlled at 0.20-0.40%, mainly for deoxidation and providing moderate solid solution strengthening.

[0053] Microalloying element configuration: A Ti-Nb composite microalloying strategy is adopted. Ti content is 0.010-0.030%, mainly forming TiN precipitates, which refine the austenite grains. Nb content is 0.010-0.030%, which can form fine carbonitride precipitates, providing additional precipitation strengthening effect. Cr content is 0.30-0.70%, mainly used to improve the hardenability and corrosion resistance of the material.

[0054] Harmful element control: S content is controlled below 0.006%, and P content is controlled below 0.010%, to minimize the adverse effects of these elements on the material's toughness and corrosion resistance.

[0055] Based on a deep understanding of the regulation mechanism of rare earth elements (such as Ce), this invention has also developed a complete low-temperature strengthening method for composite material substrates in some other embodiments. This method not only allows rare earth elements (such as Ce) to fully exert their regulatory role, but also achieves organic integration with the manufacturing process of composite materials.

[0056] Rare earth element (e.g., Ce) addition process: Rare earth master alloys are added to molten steel at a high temperature of 1580-1680℃. This temperature range ensures that rare earth elements (e.g., Ce) can be fully dissolved and uniformly distributed in the molten steel, laying the foundation for subsequent control effects.

[0057] Heating process: The heating temperature is set at 1150-1200℃, and the holding time is 60-180 min. Under these conditions, rare earth elements (such as Ce) and Cu can be fully dissolved into the austenitic matrix, while avoiding excessive grain growth.

[0058] Controlled rolling process: A two-stage control strategy is adopted. The first stage is rough rolling at a high temperature range of 950-1050℃, and the second stage is finish rolling at a medium temperature range of 800-880℃. This hot rolling process can obtain fine and uniform austenite grains, providing a favorable microstructure for subsequent phase transformation and precipitation.

[0059] Cooling process control: The cooling rate is controlled at 3-8 ℃ / s, and the cooling termination temperature is set at 480-520℃. This temperature range falls precisely within the sensitive range for Cu precipitation, creating favorable conditions for subsequent low-temperature precipitation treatment.

[0060] Low-temperature precipitation treatment: This is the core step of the entire process. The precipitation temperature is precisely controlled within the range of 420-480℃. This temperature range is the optimal precipitation temperature window determined based on the rare earth element (e.g., Ce) regulation mechanism. At this temperature, the 9R-Cu phase can fully precipitate and achieve the optimal size distribution. The holding time is set to 0.2-3 hours, with the specific time determined according to the material thickness and the desired degree of precipitation.

[0061] Experimental Example 1: Study on the Influence of Different Ce Contents on Precipitation Enhancement Effect

[0062] This experimental example uses rare earth element Ce as an example. In order to verify the effect of rare earth element Ce on reducing the precipitation strengthening temperature of copper, three sets of comparative experiments were designed to systematically study the influence of Ce content on the precipitation behavior and material properties of the nano-copper-rich phase.

[0063] 1. Experimental Material Design

[0064] According to the technical solution of the present invention, three experimental steels with different Ce contents were designed, and their specific chemical compositions are shown in Table 1 below. The 0Ce steel serves as a comparative benchmark and contains no Ce; the 1.3Ce steel has a Ce content of 0.013%, and the 1.9Ce steel has a Ce content of 0.019%, which are close to the lower and upper limits of the preferred range of 0.005-0.030% of the present invention, respectively. The Cu content of all three experimental steels is controlled within the range of 0.93-0.99%, which meets the technical requirement of 0.80-1.20% Cu content of the present invention.

[0065] Table 1. Chemical composition (wt%) of experimental steels with different Ce contents

[0066]

[0067] 2. Preparation process

[0068] according to Figure 1 The schematic diagram shown illustrates the heat treatment process for the copper-containing steel substrate, used to prepare the experimental steel:

[0069] (1) Smelting: Each experimental steel was refined in a 50 kg induction furnace. For Ce-containing steels, Ce was added to the molten steel at 1650 °C in the form of a rare earth master alloy to ensure that Ce was fully dissolved and evenly distributed.

[0070] (2) Casting: After smelting, the steel is cast into bullet-shaped ingots and cooled to room temperature.

[0071] (3) Solution treatment: Reheat the ingot to 1180℃ and hold for 120 min to ensure that the alloying elements are fully dissolved into the austenitic matrix.

[0072] (4) Controlled rolling: Seven passes of hot rolling are performed on a four-roll mill, with an initial rolling temperature of 1000℃ and a final rolling temperature of 850℃, to obtain a fine and uniform austenitic grain structure.

[0073] (5) Controlled cooling: Starting from 820℃, controlled cooling is carried out at a cooling rate of 5℃ / s, and then air-cooled to room temperature after reaching 500℃. This cooling regime puts the material microstructure in a sensitive state for Cu precipitation, creating favorable conditions for subsequent low-temperature precipitation treatment.

[0074] 3. Results Analysis

[0075] (1) 0Ce steel

[0076] 0Ce steel does not contain the rare earth element Ce and represents traditional Cu precipitation-strengthened steel. This type of steel requires aging treatment at 550-600℃ to achieve effective Cu precipitation strengthening. When aging treatment is performed below 500℃, the precipitation of the nano-copper-rich phase is extremely slow, and even extending the aging time to more than 10 hours makes it difficult to obtain sufficient precipitation strengthening effect.

[0077] Transmission electron microscopy revealed that after aging at 500℃ for 4 hours, the number density of the copper-rich nanophase in 0Ce steel remained very low, with a large average size and uneven distribution. This precipitation state contributes limitedly to strength and cannot meet the requirements of high-strength applications.

[0078] (2) 1.3Ce steel

[0079] The 1.3Ce steel, containing 0.013% Ce, showed that the addition of Ce significantly improved the Cu precipitation behavior. After aging at 460℃ for 1 h, transmission electron microscopy revealed that the number density of the copper-rich nanophase was approximately three times higher than that of the 0Ce steel, with the average size reduced to 2-5 nm and a more uniform distribution. X-ray diffraction analysis confirmed that approximately 60% of the copper-rich nanophase was the 9R-Cu phase, which is entirely consistent with the technical expectations of this invention.

[0080] Mechanical property test results show that the yield strength of 1.3Ce steel after aging at 460℃ for 1 h reaches 520 MPa, and the tensile strength reaches 650 MPa, which are 180 MPa and 120 MPa higher than those in the unaged state, respectively. The impact toughness remains above 150 J, exhibiting a good balance of strength and toughness.

[0081] (3) 1.9Ce steel

[0082] The 1.9Ce steel contains 0.019% Ce, which is close to the upper limit of the technical solution of this invention. Experimental results show that appropriately increasing the Ce content can further optimize the Cu precipitation effect.

[0083] After aging at 440℃ for 1 hour, the precipitation of the copper-rich nanophase reached its optimal state. Transmission electron microscopy revealed a further increase in the number density of the copper-rich nanophase, with the average size controlled within the range of 1-3 nm, forming a high-density copper-rich nanophase distribution. This fine precipitation structure provides excellent strengthening effects for the material.

[0084] Mechanical property tests showed that the yield strength of 1.9Ce steel reached 580 MPa and the tensile strength reached 720 MPa after aging at 440℃ for 4 hours, demonstrating a further improvement in strengthening effect compared to 1.3Ce steel. More importantly, the impact toughness of the material remained at 150 J, proving that the technical solution of this invention can maintain good toughness while improving strength.

[0085] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for reducing the precipitation temperature of copper-rich nanophases, characterized in that, By adding rare earth metal elements to the copper-containing steel, the precipitation temperature of the nano-copper-rich phase is reduced to no more than 480°C through the regulation of copper precipitation behavior by the rare earth metal elements.

2. The method for reducing the precipitation temperature of copper-rich nanophase according to claim 1, characterized in that, The proportion of 9R-Cu phase in the nano-copper-rich phase is 20-80%, and the precipitation temperature of the 9R-Cu phase is 420-480℃.

3. The method for reducing the precipitation temperature of copper-rich nanophase according to claim 1, characterized in that, The content of rare earth metal elements in the copper-containing steel is 0.005-0.030 wt% by mass.

4. The method for reducing the precipitation temperature of copper-rich nanophase according to claim 3, characterized in that, The content of rare earth metal elements in the copper-containing steel is 0.008-0.025 wt% by mass percentage.

5. The method for reducing the precipitation temperature of copper-rich nanophase according to claim 1, characterized in that, The rare earth metal element is Ce.

6. The method for reducing the precipitation temperature of copper-rich nanophase according to claim 1, characterized in that, Rare earth metal elements are added to molten steel to the target content, and the mixture is kept at a temperature not exceeding 480°C to achieve the precipitation of the nano-copper-rich phase. Furthermore, rare earth metal elements are added to molten steel at 1550-1700℃ in the form of rare earth master alloys; Furthermore, the sample was kept at 420-480℃ for 0.2-3 hours.

7. A copper-containing steel material, characterized in that, It is prepared by any one of claims 1-6.

8. The copper-containing steel according to claim 7, characterized in that, By mass percentage, the copper-containing steel contains 0.7-1.5% copper, 0.005-0.030% rare earth metals, 0.03-0.15% carbon, 0.5-1.5% manganese, and 0.1-0.6% silicon, with the balance being Fe and unavoidable impurities. The precipitation temperature of the nano-copper-rich phase in the copper-containing steel is 420-480℃.

9. The copper-containing steel according to claim 8, characterized in that, The copper-containing steel also includes one or more of the following by mass percentage: nickel 0.1-0.8%, titanium 0.005-0.05%, niobium 0.005-0.05%, and chromium 0.2-1.0%.

10. A method for low-temperature strengthening of a composite material substrate, characterized in that, The copper-containing steel prepared by any one of claims 1-5 is used as the substrate; the heat treatment temperature of the substrate is controlled at no more than 480°C to achieve precipitation strengthening of the substrate while avoiding the formation of brittle phases at the interface; Furthermore, the cladding material of the composite material is one or more of stainless steel, nickel-based alloy, and titanium alloy.

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