A rare earth strengthened high-chromium wear-resistant alloy and a preparation method thereof

Abstract

This invention relates to a rare-earth-reinforced high-chromium wear-resistant alloy and its preparation method, belonging to the field of wear-resistant materials technology. The main technical solution adopted is as follows: a rare-earth-reinforced high-chromium wear-resistant alloy, with the following chemical composition by mass percentage: C: 1.5-4.5wt%, Cr: 25-35wt%, Mo: 0.5-3.5wt%, Si: 0.2-1.0wt%, Mn: 0.2-1.0wt%, Nb: 0.01-1.0wt%, B: 0.005-0.05wt%, Ni: 0.05-2.0wt%, Ti: 0.05-1.0wt%, V: 0.05-2.0wt%, Hf: 0-0.2wt%, Zr: 0-0.2wt%, rare earth Y: 0.02-0.5wt%, rare earth La: 0.02-0.5wt%, Fe balance. This invention is mainly used to significantly improve the hardness and wear resistance of wear-resistant alloys while maintaining a certain degree of plasticity.

Description

Technical Field

[0001] This invention relates to the field of wear-resistant materials technology, and in particular to a rare earth-reinforced high-chromium wear-resistant alloy and its preparation method. Background Technology

[0002] Wear, as one of the three major failure modes of metallic materials (fracture, corrosion, and abrasion), is a dynamic microscopic process simultaneously influenced by complex factors such as mechanical, physical, and chemical processes. Due to the complexity of the actual wear conditions and processes of components, material wear often involves multiple wear mechanisms coexisting. Therefore, studying the wear mechanism of materials, improving their wear resistance, and extending their service life are urgent problems to be solved. In recent years, high-chromium wear-resistant alloys for rolling mill rolls, as a representative of third-generation wear-resistant materials, have been widely used in many fields. Although they have excellent performance compared with other materials, they still suffer from problems such as poor wear resistance and insufficient hardness.

[0003] In summary, there is an urgent need to further improve the hardness and wear resistance of high-chromium wear-resistant alloys. Summary of the Invention

[0004] In view of this, the present invention provides a rare earth reinforced high chromium wear-resistant alloy and its preparation method, the main purpose of which is to further improve the wear resistance and toughness of the wear-resistant alloy while maintaining a certain degree of plasticity.

[0005] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0006] On one hand, embodiments of the present invention provide a rare earth-reinforced high-chromium wear-resistant alloy, wherein, by mass percentage, the chemical composition of the rare earth-reinforced high-chromium wear-resistant alloy is: C: 1.5-4.5wt%, Cr: 25-35wt%, Mo: 0.5-3.5wt%, Si: 0.2-1.0wt%, Mn: 0.2-1.0wt%, Nb: 0.01-1.0wt%, B: 0.005-0.05wt%, Ni: 0.05-2.0wt%, Ti: 0.05-1.0wt%, V: 0.05-2.0wt%, Hf: 0-0.2wt%, Zr: 0-0.2wt%, rare earth Y: 0.02-0.5wt%, rare earth La: 0.02-0.5wt%, Fe balance. Preferably, in the rare earth-reinforced high-chromium wear-resistant alloy, the mass ratio of C to Cr is 0.06-0.18.

[0007] Preferably, the chemical composition of the rare earth-reinforced high-chromium wear-resistant alloy, by mass percentage, is as follows: C: 2.5-4.5wt%, Cr: 25-30wt%, Mo: 0.5-1.5wt%, Si: 0.5-1.0wt%, Mn: 0.2-1.0wt%, Nb: 0.01-0.05wt%, B: 0.01-0.05wt%, Ni: 0.5-2.0wt%, Ti: 0.2-1.0wt%, V: 0.2-1.0wt%, Hf: 0.1-0.5wt%, Zr: 0.1-0.5wt%, rare earth Y: 0.02-0.1wt%, rare earth La: 0.02-0.1wt%, Fe balance.

[0008] Preferably, in the microstructure of the rare earth-reinforced high-chromium wear-resistant alloy: carbides are dispersed and isolated within the grains and at the grain boundaries (dispersed and isolated distribution here means that the particles are discontinuous and not interconnected); wherein, the carbides include M7C3, M3C, and M 23 C6, MC (most M) 23 C6 is generally found at grain boundaries, while other carbides are commonly found within the grains; MC includes MoC and NbC; the size of the carbides is 10-40 μm, preferably 20-35 μm, and more preferably 30±2 μm; preferably, the carbides are carbide particles with rounded edges (i.e., nearly spherical carbide particles); preferably, the volume fraction of carbides in the microstructure of the rare earth-reinforced high-chromium wear-resistant alloy is 48-55%.

[0009] Preferably, the average grain size of the rare earth-reinforced high-chromium wear-resistant alloy does not exceed 400 μm.

[0010] Preferably, the rare earth reinforced high chromium wear-resistant alloy has a hardness ≥ HRC68 and an impact energy exceeding 2.0 KV2 / J.

[0011] On the other hand, embodiments of the present invention also provide a method for preparing the rare earth-reinforced high-chromium wear-resistant alloy described in any of the above claims, which includes the following steps:

[0012] 1) Smelting: Smelting alloy raw materials; the smelting process includes high-temperature refining and low-temperature refining.

[0013] 2) Casting: The alloy liquid after smelting is cast to obtain alloy ingots; preferably, the casting process includes steel molten liquid transfer casting;

[0014] 3) Heat treatment: The heat treatment process includes the following steps in sequence:

[0015] Gradient heat treatment: The alloy ingot is heated in the furnace at a first heating rate to 500-700℃ for a first heat treatment, and held at that temperature for 2-3 hours to obtain the alloy after the first heat treatment; the alloy after the first heat treatment is heated in the furnace at a second heating rate to 800-1000℃ for a second heat treatment, and held at that temperature for 4-5 hours to obtain the alloy after the second heat treatment; the alloy after the second heat treatment is heated in the furnace at a third heating rate to 1150-1180℃ for a third heat treatment, and held at that temperature for 8-10 hours, then cooled to room temperature to obtain the alloy after the third heat treatment.

[0016] Subcritical heat treatment: The alloy after the third heat treatment is placed in a tempering furnace and heated to 400-500℃ at a fourth heating rate for subcritical heat treatment. After holding at this temperature for 4-5 hours, a rare earth-reinforced high-chromium wear-resistant alloy is obtained.

[0017] Preferably, the first heating rate is 50-100℃ / hour; and / or the second heating rate is 50-100℃ / hour; and / or the third heating rate is less than or equal to 50-100℃ / hour; and / or the fourth heating rate is 50-100℃ / hour.

[0018] Preferably, in step 1), the smelting process is carried out in a medium-frequency induction furnace.

[0019] Preferably, the high-temperature refining is 1520℃-1550℃; and / or the low-temperature refining is 1200℃-1300℃; and / or the casting temperature is 1450℃-1480℃.

[0020] Preferably, in step 2): after refining, a slag remover is added to the alloy liquid to adsorb sulfides and surface slag in the alloy liquid, and the slag is removed after it is piled up, thereby reducing the content of alloy impurities and ensuring cleanliness; preferably, the slag remover is expanded perlite sand.

[0021] Compared with the prior art, the rare earth-reinforced high-chromium wear-resistant alloy and its preparation method of the present invention have at least the following beneficial effects:

[0022] On one hand, the rare earth-reinforced high-chromium wear-resistant alloy provided in this embodiment of the invention has the following chemical composition by mass percentage: C: 1.5-4.5 wt%, Cr: 25-35 wt%, Mo: 0.5-3.5 wt%, Si: 0.2-1.0 wt%, Mn: 0.2-1.0 wt%, Nb: 0.01-1.0 wt%, B: 0.005-0.05 wt%, Ni: 0.05-2.0 wt%, Ti: 0.05-1.0 wt%, V: 0.05-2.0 wt%, Hf: 0-0.2 wt%, Zr: 0-0.2 wt%, rare earth Y: 0.02-0.5 wt%, rare earth La: 0.02-0.5 wt%, Fe balance. Preferably, the mass ratio of C to Cr is 0.06-0.18. The chemical composition design of the aforementioned rare-earth-reinforced high-chromium wear-resistant alloy is explained below: Extensive research has revealed that the C / Cr ratio significantly affects carbide precipitation behavior, including precipitation temperature, carbide type, and volume fraction. Furthermore, the addition of rare-earth elements Y and La also influences the carbide growth environment. Therefore, the inventors propose that optimizing the C / Cr ratio and the addition amounts of rare-earth elements Y and La will effectively refine the as-cast microstructure of the alloy. Moreover, the appropriate addition of rare-earth elements can purify the melt, removing gaseous impurities (O, N, S) to a certain extent. The resulting La2O3 and Y2O3 can serve as heterogeneous nucleation sites for M3C and M7C3 carbides, thereby increasing the volume fraction of primary carbides and improving the alloy's wear resistance. In addition, since the atomic radii of rare-earth elements Y and La differ significantly from those of the matrix Fe, their solid dissolution in the matrix will produce considerable lattice distortion, significantly increasing the alloy's strength.

[0023] Furthermore, based on the above chemical composition, the method for preparing the rare earth-reinforced high-chromium wear-resistant alloy provided in this embodiment of the invention, through innovative heat treatment process design, further effectively improves the morphology and distribution of carbides; specifically, the morphology of carbides is gradually transformed from elongated and network-like distribution to granular, reducing carbide spalling during alloy wear and significantly improving the wear resistance of cast iron. Specifically, the microstructure of the rare earth-reinforced high-chromium wear-resistant alloy obtained after the alloy ingot with the above-mentioned composition of the present invention, after appropriate heat treatment, is as follows: the carbides are isolated and distributed, with rounded edges and uniform size.

[0024] It should be noted that the heat treatment process proposed in this invention includes a gradient high-temperature heat treatment process (i.e., a three-step gradient heat treatment) and a low-temperature subcritical heat treatment process, which effectively improves the morphology and distribution of carbides. On the one hand, while eliminating brittle impurity phases and low-melting-point eutectic phases, the multi-gradient holding process gradually dissolves the edges of M7C3 and M3C carbides in the high-chromium alloy, and the network carbides gradually transform into isolated, rounded-edge carbide particles, which are dispersed within the grains. On the other hand, during the subcritical heat treatment process, the low temperature promotes the diffusion of Mo, Nb, V, and rare earth elements into the carbides for enrichment, forming small-particle carbides. Meanwhile, the inventors discovered that the preferred alloy composition (C: 2.5-4.5wt%, Cr: 25-30wt%, Mo: 0.5-1.5wt%, Si: 0.5-1.0wt%, Mn: 0.2-1.0wt%, Nb: 0.01-0.05wt%, B: 0.01-0.05wt%, Ni: 0.5-2.0wt%, Ti: 0.2-1.0wt%, V: 0.2-1.0wt%, Hf: 0.1-0.5wt%, Zr: 0.1-0.5wt%, rare earth Y: 0.02-0.1wt%) (La: 0.02-0.1wt%, Fe balance) During the heat treatment at this temperature, the edges of blocky carbides such as M7C3 and M3C are more easily dissolved rapidly. The network carbides gradually transform into isolated, rounded carbide particles, which are eventually dispersed in large quantities within the crystals. Together with the dispersed M3C carbides generated by solid-state phase transformation during the low-temperature subcritical heat treatment process, secondary hardening is achieved, which improves the material hardness and its wear resistance. Compared with other inventions, a higher volume fraction of spherical carbide particles (48-55%) is uniformly distributed, which improves the alloy hardness and wear resistance.

[0025] In a preferred embodiment, the average grain size of the rare-earth-reinforced high-chromium wear-resistant alloy of the present invention does not exceed 400 μm. This index is achieved through reasonable rare-earth content (the content of rare-earth Y and La is controlled within the range of 0.02-0.1%, during which a large number of high-melting-point rare-earth inclusions are formed during the solidification process of the melt, which can act as heterogeneous nucleation points, improve the alloy nucleation rate, and thus significantly refine the grains; on the other hand, the most active rare-earth elements Y and La will be enriched at the solid / liquid interface front during solidification, inhibiting grain growth and achieving the purpose of refining the as-cast structure) and control of the heating rate of heat treatment (rapid heating will accelerate the release of internal stress in the ingot during solidification, leading to ingot cracking, while long-term slow heating will lead to severe oxidation of the ingot and coarse grain size; the heating rate designed in the present invention is specific to the composition of the present invention and has been simulated by thermodynamic simulation software and verified by experiments). The grain size index proposed in the present invention can achieve a higher level than other technologies (the average grain size of alloys produced by conventional technologies is generally at the millimeter level, and the size varies greatly).

[0026] In a preferred embodiment of the present invention, to improve the hardness and wear resistance of the new alloy, the C / Cr ratio and the content of rare earth elements such as Y and La are optimized and adjusted (C: 2.5-4.5wt%, Cr: 25-30wt%, Mo: 0.5-1.5wt%, Si: 0.5-1.0wt%, Mn: 0.2-1.0wt%, Nb: 0.01-0.05wt%, B: 0.01-0.05wt%, Ni: 0.5-2.0wt%, Ti: 0.2-1.0wt%, V: 0.2-1.0wt%, Hf: 0.1-0.5wt%, Zr: 0.1-0.5wt%, rare earth Y: 0.02-0.1wt%, rare earth La: 0.02-0.1wt%, Fe balance). The optimized control of elements such as C and Cr results in the presence of various carbides (such as MC, Mn, and Cr) in the alloy. 23 C6, M7C3, and M3C carbides, where M represents metallic elements such as Cr, Nb, Mo, and Zr, and low-melting-point eutectic segregating phases; simultaneously, rare earth elements have a strong affinity for O and S, and the precipitation temperatures and melting points of rare earth inclusions and various carbide phases differ during solidification. Therefore, this invention uses a heat treatment process with multiple heat treatment steps (600℃, 900℃, and 1160℃) to, respectively, reduce cracking caused by rapid release of solidification internal stress during ingot heat treatment (600℃), ensure the stability of easily segregating elements such as Cr and Ti in the alloy matrix phase, and prevent irreversible defects such as overheating and porosity due to the pre-melting of some low-melting-point eutectic phases (900℃), and promote the formation of low-melting-point unstable carbides, such as M... 23 The slow re-dissolution of C6 and rare earth inclusions ensures a dense and pore-free matrix structure. At 1160℃, no other segregation or inclusion phases are retained except for high-temperature stable carbide MC, M7C3 and M3C particles.

[0027] It should be noted that traditional stepless heat treatment directly and rapidly precipitates various carbides during the heating process. However, high-temperature treatment can easily lead to the simultaneous dissolution of various carbides with different initial melting points, resulting in irreversible defects such as overheating and porosity. The heat treatment in this invention is characterized by: 1. A multi-stage gradient heat treatment process is established to ensure that the alloy is free from segregation and harmful impurities, resulting in a dense matrix structure and no heat treatment pores affecting the performance of the new alloy; 2. By adding a subcritical heat treatment process, during the holding period of this heat treatment, due to the adjustment of the C / Cr addition ratio, C and Cr can be desoluble from austenite rather than transformed into pearlite, resulting in dispersed secondary carbides (MC, M7C3, M...). 23C6 precipitates from austenite and gradually transforms into more stable and wear-resistant M3C carbides, a process that increases the carbide volume fraction in the alloy. On the other hand, low temperatures promote the diffusion of Mo, Nb, V, and rare earth elements into carbides, forming small-particle carbides. Meanwhile, studies have found that the preferred alloy composition (C: 2.5-4.5wt%, Cr: 25-30wt%, Mo: 0.5-1.5wt%, Si: 0.5-1.0wt%, Mn: 0.2-1.0wt%, Nb: 0.01-0.05wt%, B: 0.01-0.05wt%, Ni: 0.5-2.0wt%, Ti: 0. (2-1.0wt%, V: 0.2-1.0wt%, Hf: 0.1-0.5wt%, Zr: 0.1-0.5wt%, rare earth Y: 0.02-0.1wt%, rare earth La: 0.02-0.1wt%, Fe balance) During the heat treatment at this temperature, the edges of blocky carbides such as M7C3 and M3C are more easily dissolved rapidly. The network carbides gradually transform into isolated carbide particles with rounded edges, which are eventually dispersed in large quantities within the crystal. Together with the dispersed M3C carbides generated by solid-state phase transformation during the low-temperature subcritical heat treatment process, they achieve secondary hardening, which improves the hardness of the material and enhances its resistance to abrasive wear.

[0028] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0029] Figure 1 The image shows the microstructure of the rare earth-reinforced high-chromium wear-resistant alloy described in Example 1.

[0030] Figure 2 The image shows the microstructure of the rare earth-reinforced high-chromium wear-resistant alloy described in Example 2.

[0031] Figure 3 The image shows the microstructure of the rare earth-reinforced high-chromium wear-resistant alloy described in Example 3.

[0032] Figure 4 Micrograph of the rare earth-reinforced high-chromium wear-resistant alloy described in Comparative Example 1;

[0033] Figure 5 Micrograph of the rare earth-reinforced high-chromium wear-resistant alloy described in Comparative Example 2;

[0034] Figure 6 Micrograph of the rare earth-reinforced high-chromium wear-resistant alloy described in Comparative Example 3. Detailed Implementation

[0035] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0036] In alloys, the strengthening effect of primary carbides is significant. The type and morphology of primary carbides differ in alloys with different chemical compositions, and they have a considerable impact on the alloy's microstructure and properties during subsequent heat treatment and service. When the composition is not properly controlled or the casting process is unreasonable, some primary carbides with morphologies detrimental to the alloy's properties (primary carbides include MC, M...) will be generated in the alloy. 23 C6, M7C3, and M3C alloys exhibit a wide variety of primary carbide shapes, often appearing as elongated strips, rods, blocks, discontinuous networks, or continuous distributions at grain boundaries, or even large agglomerations in certain areas, resulting in highly complex states. These can include film-like primary carbides growing along grain boundaries, bulky primary carbides, and needle-like primary carbides. All these carbide morphologies can have a catastrophic impact on alloy properties. Therefore, the influence of primary carbides on alloy properties cannot be ignored.

[0037] This invention provides a rare-earth-reinforced high-chromium wear-resistant alloy and its preparation method. The invention optimizes the chemical composition of the high-chromium alloy, such as adjusting the C / Cr ratio, particularly the addition of rare-earth elements Y and La (one of the key innovations lies in the addition of certain rare-earth elements La and Y). With the addition of rare-earth elements, on the one hand, the amount of rare-earth elements added, along with the specific heat treatment process (temperature and time) of this invention, such as gradient heating and the setting of multiple heat-holding steps, gradually forms La2O3 and Y2O3. La2O3 and Y2O3 act as heterogeneous nucleation cores for M7C3 type carbides, increasing the number and refining the primary carbides. On the other hand, the morphology of the carbides gradually changes from elongated strips to rounded granules, reducing carbide spalling during alloy wear and significantly improving the wear resistance of cast iron. Simultaneously, by optimizing the gradient high-temperature heat treatment process and combining it with the low-temperature subcritical heat treatment process, brittle phases and low-melting-point phases are eliminated. At the same time, the multi-gradient heat preservation process gradually dissolves the edges of M7C3 and M3C carbides in the high-chromium alloy, and the network carbides gradually transform into isolated, rounded carbide particles that are dispersed within the grains (compared with other existing technologies, this invention can achieve a higher volume fraction of spherical carbide particles (48-55%) uniform distribution, which is about 15-20%). In addition, the subcritical heat treatment process added in this invention promotes the precipitation of secondary carbides (Mo-rich and Nb-rich carbides MoC and NbC), achieving secondary hardening, which improves the material hardness and its wear resistance.

[0038] The main features of this invention are as follows:

[0039] This invention provides a rare-earth-reinforced high-chromium wear-resistant alloy. The chemical composition of the rare-earth-reinforced high-chromium wear-resistant alloy, by mass percentage, is: C: 1.5-4.5 wt%, Cr: 25-35 wt%, Mo: 0.5-3.5 wt%, Si: 0.2-1.0 wt%, Mn: 0.2-1.0 wt%, Nb: 0.01-1.0 wt%, B: 0.005-0.05 wt%, Ni: 0.05-2.0 wt%, Ti: 0.05-1.0 wt%, V: 0.05-2.0 wt%, Hf: 0-0.2 wt%, Zr: 0-0.2 wt%, rare-earth Y: 0.05-0.5 wt%, rare-earth La: 0.05-0.5 wt%, Fe balance. Preferably, the mass ratio of C to Cr is 0.06-0.18.

[0040] The preferred design is as follows: the chemical composition of the rare earth reinforced high chromium wear-resistant alloy, by mass percentage, is: C: 2.5-4.5wt%, Cr: 25-30wt%, Mo: 0.5-1.5wt%, Si: 0.5-1.0wt%, Mn: 0.2-1.0wt%, Nb: 0.01-0.05wt%, B: 0.01-0.05wt%, Ni: 0.5-2.0wt%, Ti: 0.2-1.0wt%, V: 0.2-1.0wt%, Hf: 0.1-0.5wt%, Zr: 0.1-0.5wt%, rare earth Y: 0.02-0.1wt%, rare earth La: 0.02-0.1wt%, Fe balance.

[0041] Regarding the chemical composition of the rare earth-reinforced high-chromium wear-resistant alloy of the present invention: rare earth elements are added to the high-chromium wear-resistant alloy, and carbides MC and M are generated by reacting with elements such as C, Cr, Nb, Mo, and Zr. 23 C6, M7C3, and M3C.

[0042] As can be seen from the alloy composition of the present invention, a high degree of alloying inevitably leads to problems such as segregation and uneven structure in the ingot. In order to improve the uniformity of the alloy's structure and properties, the ingot is heat-treated by adopting a staged heating and holding heat treatment process combined with subcritical heat treatment. Here, by optimizing and adjusting the C / Cr ratio and adding rare earth elements such as Y and La, a refined as-cast structure can be obtained, including coarse columnar dendrites with a high volume fraction and coarse lamellar and fibrous carbides MC and M7C3 and M3C carbides continuously distributed along the grain boundaries. Then, through the specific heat treatment process described above, the alloy is free of coarse columnar dendrites and coarse, long, lamellar or fibrous carbides continuously distributed along the grain boundaries. The carbides in the alloy are isolated, with rounded edges, uniform in size, and dispersed within the grains. After this heat treatment, the microstructure of the rare-earth strengthened high-chromium wear-resistant alloy mainly consists of uniformly dispersed carbides and grains with an average grain size of 400 μm, resulting in a macroscopic hardness exceeding 68 HRC and an impact energy exceeding 2.0 KV² / J. This leads to higher wear resistance and service life, making it suitable for the preparation of various types of wear-resistant materials and workpieces.

[0043] The added rare earth elements are difficult to integrate into the alloy and easily combine with the gases O, N, and S in the high-temperature alloy to form rare earth inclusions and impurities. Therefore, it is necessary to remove these impurities through refining processes at different temperatures.

[0044] High-temperature refining accelerates the dissolution of some refractory elements and removes some rare earth inclusions and impurities. Low-temperature refining results in more uniform molten steel, making the alloy ingot structure more uniform and free from obvious segregation. This makes it less likely for carbides to agglomerate in certain areas, leading to substandard performance.

[0045] During heat treatment, the heating rate must be within a certain range. The laboratory has conducted calculations because there are many alloying elements and rare earth elements are added. The solidification process of the ingot will generate a lot of internal stress. If the heating rate is too fast, it will accelerate the release of internal stress and cause direct cracking. If the heating rate is too slow, it will accelerate grain growth and form coarse grains, and at the same time, it will cause severe oxidation. The heating rate was selected based on this.

[0046] Subcritical treatment is based on the solidification precipitation phase diagram of the alloy. It involves heat treatment at the lowest temperature at which austenite transforms into martensite and the lowest temperature at which traditional M7C3 carbides are most likely to transform into new MoC and NbC carbides (critical temperature). At this temperature, the carbides will spheroidize and disperse without dissolving.

[0047] This alloy contains various carbides (primary MC, M). 23C6, M7C3, and M3C) are used, and the precipitation temperatures and melting points of various carbides are different. Multiple heat preservation steps (600℃, 900℃, 1160℃) are set for each. The purposes are, in order, to reduce cracking caused by the rapid release of solidification internal stress during ingot heat preservation (600℃), to ensure the stability of easily segregated elements such as Cr and Ti in the alloy matrix phase, and to prevent irreversible defects such as overheating and porosity due to the pre-melting of some low-melting-point eutectic phases (900℃), and to promote the formation of low-melting-point unstable carbides, such as M... 23 The slow re-dissolution of C6 and rare earth inclusions ensures a dense and pore-free matrix structure. At 1160℃, only high-temperature stable carbide particles (MC, M7C3, and M3C) are retained, with no other segregation or inclusion phases. Traditional stepless heat treatment directly and rapidly precipitates various carbides during heating, but high-temperature treatment easily leads to the simultaneous dissolution of various carbides with different initial melting points, resulting in irreversible defects such as overheating and porosity. This invention, however, establishes a multi-stage gradient heat treatment process that ensures a dense matrix structure and eliminates heat-treated pores that could affect the performance of the new alloy, while preventing the presence of segregated or harmful impurities.

[0048] The characteristic of the heat treatment in this invention is that it maintains the precipitation temperature of each carbide for a sufficiently long time to ensure maximum precipitation. Each step has a specific function; the low-temperature step ensures the precipitation of several low-temperature carbides, such as M... 23 The precipitation of C6, M7C3, and M3C, and the high-temperature step are mainly used to promote the dissolution of dendritic carbides at the edges and corners, promote the diffusion of rare earth elements, enrich them in carbides, and modify and regulate the morphology of carbides.

[0049] In this invention, the average grain size of the alloy ingot does not exceed 400 μm. For as-cast structures, this average grain size is already very small, thanks to a reasonable heat treatment heating rate. Too fast a rate will cause cracking, while too slow a rate will result in severe oxidation and extremely coarse grain size, which would be 2-3 times that of this invention.

[0050] Another embodiment of the present invention provides a method for preparing a rare earth-reinforced high-chromium wear-resistant alloy, which includes the following steps:

[0051] 1) Smelting: Smelting alloy raw materials; the smelting process includes high-temperature refining and low-temperature refining.

[0052] The high-temperature refining process is 1520℃-1550℃;

[0053] The low-temperature refining process is carried out at 1200℃-1300℃;

[0054] The casting temperature is 1450℃-1480℃;

[0055] 2) Casting: The molten alloy is cast to obtain an alloy ingot; preferably, the casting process includes steel molten metal transfer casting; wherein,

[0056] 3) Heat treatment: The heat treatment process includes the following steps in sequence:

[0057] Gradient heat treatment: The alloy ingot is heated in the furnace at a first heating rate to 500-700℃ (preferably 600℃) for a first heat treatment, and held at that temperature for 2-3 hours to obtain the alloy after the first heat treatment; the alloy after the first heat treatment is heated in the furnace at a second heating rate to 800-1000℃ (preferably 900℃) for a second heat treatment, and held at that temperature for 4-5 hours to obtain the alloy after the second heat treatment; the alloy after the second heat treatment is heated in the furnace at a third heating rate to 1150-1180℃ (preferably 1160℃) for a third heat treatment, and held at that temperature for 8-10 hours, then cooled to room temperature to obtain the alloy after the third heat treatment.

[0058] Subcritical heat treatment: The alloy after the third heat treatment is placed in a tempering furnace and heated to 400-500℃ at a fourth heating rate for subcritical heat treatment. After holding at this temperature for 4-5 hours, a rare earth-reinforced high-chromium wear-resistant alloy is obtained.

[0059] It should be noted that:

[0060] (1) Before heat treatment, the microstructure of the alloy ingot is as follows: there is severe macrosegregation, the carbide particles are of different sizes and randomly agglomerated. There are a large number of flocculent and dot-like low-melting-point inclusions in the river-like connected martensite.

[0061] (2) For gradient heat treatment:

[0062] First heat treatment: Slowly eliminate the internal stress generated by the solidification of large ingots (the wear-resistant alloy in this invention is mainly used to produce wear-resistant rings for large impellers or tunnel boring machines, which are extremely large, with a diameter of about 8-10 meters. Such large ingots will inevitably produce greater segregation and core solidification stress than small ingots in the laboratory).

[0063] Second heat treatment: Eliminate low-melting-point phases in the alloy (various inclusion phases, including low-melting-point eutectics, which have complex compositions and low melting points and no specific representation method), while ensuring the stability of easily segregating elements such as Cr and Ti in the alloy matrix phase, and avoiding overheating, voids, etc. due to the premature melting of some low-melting-point eutectic phases at excessively high temperatures (>1000℃).

[0064] Third heat treatment: further eliminates unstable eutectic phases with slightly higher melting points, while promoting M 23C6, M7C3 and rare earth inclusions are slowly re-dissolved to ensure a dense and pore-free matrix structure, while retaining the primary insoluble MC carbide (which has a high melting point and is usually difficult to re-dissolve; in addition, the amount of this carbide is small and it is not the main control target), ensuring that no other segregation or inclusion phases are retained.

[0065] Here, after the above three-step gradient heat treatment, during the cooling process, fine particulate M particles begin to precipitate diffusely at the grain boundaries and within the grains. 23 C6, M7C3.

[0066] (3) Subcritical heat treatment: solid phase transformation occurs, the residual austenite transforms into martensite, and fine and dispersed secondary carbides (M3C carbides and MC carbides) are precipitated. At the same time, during the heat preservation process, the corners of MC and M3C carbides dissolve and transform into isolated carbide particles with rounded edges.

[0067] The present invention will be further illustrated by the following embodiments:

[0068] The chemical composition of the wear-resistant alloys of Examples 1-3 and Comparative Examples 1-3 of the present invention is shown in Table 1.

[0069] Table 1 shows the chemical composition (wt%) of the alloys in the embodiments of the present invention and the alloys in the comparative examples.

[0070]

[0071] Example 1

[0072] In Example 1, a rare earth-reinforced high-chromium wear-resistant alloy was prepared. Its chemical composition is shown in Table 1 (C / Cr ratio is 0.125).

[0073] The preparation steps are mainly as follows:

[0074] Smelting and casting: The alloy raw materials are smelted (including high-temperature refining and low-temperature refining), and the molten steel is transferred and cast to obtain alloy ingots. The high-temperature refining temperature is 1520℃, the low-temperature refining temperature is 1200℃, and the casting temperature is 1450℃.

[0075] Heat treatment: The alloy ingot is heat treated to obtain a rare earth-reinforced high-chromium wear-resistant alloy.

[0076] The heat treatment process includes the following steps in sequence:

[0077] Gradient heat treatment: The alloy ingot is heated in a furnace at an average heating rate of 60°C / hour to 600°C for a first heat treatment, and held for 3 hours to obtain the alloy after the first heat treatment. The alloy after the first heat treatment is heated in a furnace at a heating rate of 50°C / hour to 900°C for a second heat treatment, and held for 5 hours to obtain the alloy after the second heat treatment. The alloy after the second heat treatment is heated in a furnace at a rate of 50°C / hour to 1160°C, held for 10 hours, and then air-cooled to room temperature to obtain the alloy after the third heat treatment.

[0078] Subcritical heat treatment: The alloy after the third heat treatment is placed in a tempering furnace at ≤200℃ and heated to 450℃ at a rate of 50℃ / hour, and held for 5 hours to obtain a rare earth reinforced high chromium wear-resistant alloy.

[0079] Figure 1 The image shows the microstructure of the rare-earth-reinforced high-chromium wear-resistant alloy described in Example 1; from Figure 1 It can be seen that in the microstructure of the rare earth-reinforced high-chromium wear-resistant alloy prepared in Example 1, the carbides are isolated and dispersed, with rounded edges; the size of the carbides is 15±5μm. The carbides include M7C3, M3C, and M... 23 C6, MC (most M) 23 C6 is generally found at grain boundaries, while other carbides are commonly found within the grains; the average grain size of rare earth-reinforced high-chromium wear-resistant alloys (including MoC and NbC) does not exceed 400 μm. The mass fraction of carbides in rare earth-reinforced high-chromium wear-resistant alloys is approximately 52-55%.

[0080] Example 2

[0081] In Example 2, a rare earth-reinforced high-chromium wear-resistant alloy was prepared. Its chemical composition is shown in Table 1 (C / Cr ratio is 0.125).

[0082] The preparation steps are mainly as follows:

[0083] Smelting and casting: The alloy raw materials are smelted (including high-temperature refining and low-temperature refining), and the molten steel is transferred and cast to obtain alloy ingots. The high-temperature refining temperature is 1550℃, the low-temperature refining temperature is 1300℃, and the casting temperature is 1480℃.

[0084] Heat treatment: The alloy ingot is heat treated to obtain a rare earth-reinforced high-chromium wear-resistant alloy.

[0085] The heat treatment process includes the following steps in sequence:

[0086] Gradient heat treatment: The alloy ingot is heated in a furnace to 600°C at an average heating rate of 60°C / hour and held for 3 hours to obtain the alloy after the first heat treatment. The alloy after the first heat treatment is then heated in a furnace to 900°C at a heating rate of 50°C / hour and held for 5 hours to obtain the alloy after the second heat treatment. The alloy after the second heat treatment is then heated in a furnace to 1160°C at a heating rate of 50°C / hour and held for 10 hours, then air-cooled to room temperature to obtain the alloy after the third heat treatment.

[0087] Subcritical heat treatment: The alloy after the third heat treatment is placed in a tempering furnace at ≤200℃ and heated to 450℃ at a rate of 50℃ / hour, and held for 5 hours to obtain a rare earth reinforced high chromium wear-resistant alloy.

[0088] Figure 2 The image shows the microstructure of the rare-earth-reinforced high-chromium wear-resistant alloy described in Example 2; from Figure 2 It can be seen that in the microstructure of the rare earth-reinforced high-chromium wear-resistant alloy prepared in Example 2, the carbides are isolated and dispersed, with rounded edges; the size of the carbides is 30±2μm. The carbides include M7C3, M3C, and M... 23 C6, MC (most M) 23 C6 is generally found at grain boundaries, while other carbides are commonly found within the grains; the average grain size of rare earth reinforced high chromium wear-resistant alloys (including MoC and NbC) does not exceed 400 μm; the mass fraction of carbides in rare earth reinforced high chromium wear-resistant alloys is about 50-53%.

[0089] Example 3

[0090] In Example 3, a rare earth-reinforced high-chromium wear-resistant alloy was prepared. Its chemical composition is shown in Table 1 (C / Cr ratio is 0.125).

[0091] The preparation steps are mainly as follows:

[0092] Smelting and casting: The alloy raw materials are smelted (including high-temperature refining and low-temperature refining), and the molten steel is transferred and cast to obtain alloy ingots. The high-temperature refining temperature is 1530℃, the low-temperature refining temperature is 1250℃, and the casting temperature is 1460℃.

[0093] Heat treatment: The alloy ingot is heat treated to obtain a rare earth-reinforced high-chromium wear-resistant alloy.

[0094] The heat treatment process includes the following steps in sequence:

[0095] Gradient heat treatment: The alloy ingot is heated in a furnace to 600°C at an average heating rate of 60°C / hour and held for 3 hours to obtain the alloy after the first heat treatment. The alloy after the first heat treatment is then heated in a furnace to 900°C at a heating rate of 50°C / hour and held for 5 hours to obtain the alloy after the second heat treatment. The alloy after the second heat treatment is then heated in a furnace to 1160°C at a heating rate of 50°C / hour and held for 10 hours, followed by air cooling to room temperature to obtain the alloy after the third heat treatment.

[0096] Subcritical heat treatment: The alloy after the third heat treatment is placed in a tempering furnace at ≤200℃ and heated to 450℃ at a rate of 50℃ / hour, and held for 5 hours to obtain a rare earth reinforced high chromium wear-resistant alloy.

[0097] Figure 3 Micrograph of the rare earth-reinforced high-chromium wear-resistant alloy described in Example 3; from Figure 3 It can be seen that in the microstructure of the rare earth-reinforced high-chromium wear-resistant alloy prepared in Example 3, the carbides are isolated and dispersed, with rounded edges; the size of the carbides is 30±2μm. The carbides include M7C3, M3C, and M... 23 C6, MC (most M) 23 C6 is generally found at grain boundaries, while other carbides are commonly found within the grains; the average grain size of rare earth reinforced high chromium wear-resistant alloys (including MoC and NbC) does not exceed 400 μm; the mass fraction of carbides in rare earth reinforced high chromium wear-resistant alloys is approximately 52%.

[0098] Comparative Example 1

[0099] Comparative Example 1 prepared a high-chromium wear-resistant alloy, the chemical composition of which is shown in Table 1 (C / Cr ratio is 0.05).

[0100] The preparation steps are mainly as follows:

[0101] Smelting and casting: The alloy raw materials are smelted (including high-temperature refining and low-temperature refining), and the molten steel is transferred and cast to obtain alloy ingots. The high-temperature refining temperature is 1530℃, the low-temperature refining temperature is 1250℃, and the casting temperature is 1460℃.

[0102] Heat treatment: The alloy ingot is heat treated to obtain a high-chromium wear-resistant alloy.

[0103] The heat treatment process includes the following steps in sequence:

[0104] First heat treatment: The alloy ingot is heated to 600°C in the furnace at a heating rate of 60°C / hour and held for 3 hours to obtain the alloy after the first heat treatment.

[0105] Second heat treatment: The alloy after the first heat treatment is heated to 900°C in the furnace at a heating rate of 50°C / hour and held for 5 hours to obtain the alloy after the second heat treatment.

[0106] Third heat treatment: The alloy after the second heat treatment is heated to 1160°C in the furnace at a heating rate of 50°C / hour, held for 10 hours, and then air-cooled to room temperature to obtain a high-chromium wear-resistant alloy.

[0107] Figure 4 A photograph of the microstructure of the high-chromium wear-resistant alloy described in Comparative Example 1; from Figure 4 It can be seen that the carbide content of the reinforced high-chromium wear-resistant alloy in Comparative Example 1 is significantly reduced and is distributed in a lamellar shape, with the grains mainly growing as slender columnar crystals.

[0108] It should be noted that the C / Cr ratio, composition, and heat treatment process in Comparative Example 1 are different from those in Example 1.

[0109] Comparative Example 2

[0110] Comparative Example 2 provides a high-chromium wear-resistant alloy, the chemical composition of which is shown in Table 1.

[0111] The preparation steps are mainly as follows:

[0112] Smelting and casting: The alloy raw materials are smelted (including high-temperature refining and low-temperature refining), and the molten steel is transferred and cast to obtain alloy ingots. The high-temperature refining temperature is 1530℃, the low-temperature refining temperature is 1250℃, and the casting temperature is 1460℃.

[0113] Heat treatment: The alloy ingot is heat treated to obtain a high-chromium wear-resistant alloy.

[0114] The heat treatment process includes the following steps in sequence:

[0115] First heat treatment: The alloy ingot is heated to 600°C in the furnace at a heating rate of 60°C / hour and held for 3 hours to obtain the alloy after the first heat treatment.

[0116] Second heat treatment: The alloy after the first heat treatment is heated to 900°C in the furnace at a heating rate of 50°C / hour and held for 5 hours to obtain the alloy after the second heat treatment.

[0117] Third heat treatment: The alloy after the second heat treatment is heated to 1160°C in the furnace at a heating rate of 50°C / hour, held for 10 hours, and then air-cooled to room temperature to obtain a high-chromium wear-resistant alloy.

[0118] Figure 5Micrograph of the rare earth-reinforced high-chromium wear-resistant alloy described in Comparative Example 2; from Figure 5 It can be seen that the amount of carbides in the alloy of Comparative Example 2 is not much different from that in the alloys of Examples 1-3, but there are significant differences in the morphology, size, and distribution characteristics of the carbides. The carbide particles in Comparative Example 2 are significantly larger in size, with obvious sharp edges and corners, and mainly exhibit a large-area network-like irregular distribution (marked with yellow circles inside the grid, where no carbides are present). This distribution pattern of carbides is not conducive to improving the wear resistance and strength of the alloy.

[0119] It should be noted that the heat treatment process in Comparative Example 2 is different from that in Example 1.

[0120] Comparative Example 3

[0121] Comparative Example 3 provides a high-chromium wear-resistant alloy, the chemical composition of which is shown in Table 1.

[0122] The preparation steps are mainly as follows:

[0123] Smelting and casting: The alloy raw materials are smelted (including high-temperature refining and low-temperature refining), and the molten steel is transferred and cast to obtain alloy ingots. The high-temperature refining temperature is 1530℃, the low-temperature refining temperature is 1250℃, and the casting temperature is 1460℃.

[0124] Heat treatment: The alloy ingot is heat treated to obtain a high-chromium wear-resistant alloy.

[0125] The heat treatment process includes the following steps in sequence:

[0126] Gradient heat treatment: The alloy ingot is heated to 600°C in a furnace at a heating rate of 60°C / hour and held for 3 hours to obtain the alloy after the first heat treatment; the alloy after the first heat treatment is heated to 900°C in a furnace at a heating rate of 50°C / hour and held for 5 hours to obtain the alloy after the second heat treatment; the alloy after the third heat treatment is heated to 1100°C in a furnace at a heating rate of 50°C / hour and held for 10 hours, then air-cooled to room temperature to obtain the alloy after the third heat treatment.

[0127] Subcritical heat treatment: The alloy after the third heat treatment is placed in a tempering furnace at ≤200℃ for subcritical heat treatment. The temperature is increased to 450℃ with the furnace at a heating rate of 50℃ / hour and held for 5 hours to obtain a high-chromium wear-resistant alloy.

[0128] Figure 6 Micrograph of the rare earth-reinforced high-chromium wear-resistant alloy described in Comparative Example 3; from Figure 6 It can be seen that the alloy microstructure exhibits obvious fibrous characteristics, and the carbides (white) are distributed in a network and dendritic pattern (see [reference]). Figure 6 (The white part in the middle).

[0129] The performance of the high-chromium wear-resistant alloys prepared in Examples 1-3 and Comparative Examples 1-3 was tested, and the results are shown in Table 2.

[0130] Table 2 shows the room temperature Rockwell hardness and corresponding impact toughness of high-chromium wear-resistant alloys.

[0131] Rockwell hardness HRC <![CDATA[Impact energy KV2 / J]]> Example 1 69.41±0.2 2.2 Example 2 69.15±0.2 2.3 Example 3 68.53±0.4 2.3 Comparative Example 1 56.31±0.3 1.7 Comparative Example 2 59.55±0.2 1.5 Comparative Example 3 58.80±0.3 1.5

[0132] From Embodiments 1-3 and Comparative Examples 1-3 of the present invention, Figure 1-6 The data in Table 2 can illustrate that:

[0133] 1. As can be seen from Table 2, the rare earth-reinforced high-chromium wear-resistant alloys prepared in Examples 1-3 exhibit good room-temperature Rockwell hardness and impact toughness. Compared with Comparative Examples 1-3, the macroscopic Rockwell hardness of the high-chromium wear-resistant alloy castings increased by 15-20%, and the impact toughness increased by 15%-40%. Furthermore, the wear resistance of wear-resistant alloys is positively correlated with hardness; therefore, the rare earth-reinforced high-chromium wear-resistant alloys prepared in the embodiments of this invention also possess good wear resistance.

[0134] 2. The heat treatment in this embodiment of the invention, by setting heat preservation steps at different high-temperature stages (600℃, 900℃, 1160℃), sequentially promotes the dissolution of low-melting-point eutectic carbides and rare earth inclusions, and the complete re-dissolution of segregated dendrites, thus avoiding irreversible defects such as overheating and porosity caused by simultaneous dissolution of various precipitates with different initial melting points during a single high-temperature treatment. This ensures a dense matrix structure without porosity. After heat treatment at 1160℃, except for high-temperature stable carbides MC, M7C3, and M... 23 No other segregated or inclusion phases are retained outside the C6 particles. Subsequently, through a low-temperature subcritical heat treatment process, on the one hand, a large amount of carbides are slowly re-precipitated to ensure the strength and hardness of the alloy. On the other hand, unlike other technologies, the low-temperature subcritical heat treatment process of this invention, combined with composition design (e.g., comprehensive adjustment of C, Cr and rare earth elements), can promote the transformation of martensitic phase into carbides. In this process, it is easier for the edges of carbides such as M7C3 and M3C to dissolve rapidly than other technologies. The network carbides gradually transform into isolated, rounded carbide particles, which are eventually dispersed in large quantities within the grains. This achieves a higher volume fraction (48-55%) of spherical carbide particles with uniform distribution compared to other technologies, improving the alloy's hardness and wear resistance while ensuring the material's plasticity.

[0135] 3. For Comparative Example 1:

[0136] Unlike Figure 1-3 ,from Figure 4As can be seen from the results, due to the low C content, high Cr content (the change in C / Cr ratio significantly affects the number of carbides) and the absence of rare earth elements in Comparative Example 1, the carbide content in the alloy is significantly reduced and is distributed in a plate-like manner, with the grains mainly growing as slender columnar crystals.

[0137] This indicates that the C / Cr ratio and the addition of rare earth elements Y and La alter the carbide growth environment, refining the as-cast microstructure of the alloy. Appropriate addition of rare earth elements can purify the melt, removing gaseous impurities (O, N, S) to some extent. The formation of La2O3 and Y2O3 can serve as heterogeneous nucleation sites for M3C2 and M7C3 carbides, increasing the volume fraction of primary carbides and thus improving the alloy's wear resistance. Furthermore, due to the significant difference in atomic radii between rare earth elements Y and La and the matrix Fe, the solid solution and matrix will produce considerable lattice distortion, significantly enhancing the alloy's strength.

[0138] In addition, as can be seen from Table 1, the composition and heat treatment process in Comparative Example 1 resulted in lower alloy hardness and impact toughness.

[0139] 4. For Comparative Example 2:

[0140] Figure 5 The amount of carbides in Figure 1-3 The carbides in the samples were similar, but their morphology, size, and distribution characteristics varied considerably. This is because Comparative Example 2 lacked a low-temperature subcritical heat treatment process following high-temperature heat treatment.

[0141] The low-temperature subcritical heat treatment process makes it easier for the edges of blocky carbides such as M7C3 and M3C to dissolve rapidly during the heat treatment process. The network carbides gradually transform into isolated carbide particles with rounded edges that are dispersed within the crystal.

[0142] Therefore, in Comparative Example 2 Figure 5 The carbide particles in the alloy are mainly distributed in a network, and such uneven network distribution is not conducive to improving the toughness and strength of the alloy.

[0143] 5. For Comparative Example 3:

[0144] The difference between Comparative Example 3 and Examples 1-3 is that the maximum temperature of the gradient heat treatment process is lower, set at 1100℃, followed by a subcritical low-temperature heat treatment test at 450℃. The results show that the carbide morphology is closely related to the maximum temperature of the high-temperature multi-stage gradient heat treatment process; excessively low temperatures (1100℃) make it difficult to achieve the goal of dissolving the original dendritic morphology carbides in the alloy of this invention. Therefore, the microstructure of Comparative Example 3 exhibits obvious fibrous characteristics, and the carbides (see...) Figure 6The white portion (in the image) exhibits a network and dendritic distribution. Similarly, this cross-distribution of network and dendritic carbides significantly reduces the toughness and strength of the alloy (as shown in Table 1).

[0145] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A rare earth strengthened high chromium wear resistant alloy characterized in that, The chemical composition of the rare earth strengthened high chromium wear-resistant alloy is, in mass percentage: C: 1.5-4.5wt%, Cr: 25-35wt%, Mo: 0.5-3.5wt%, Si: 0.2-1.0wt%, Mn: 0.2-1.0wt%, Nb: 0.01-1.0wt%, B: 0.005-0.05wt%, Ni: 0.05-2.0wt%, Ti: 0.05-1.0wt%, V: 0.05-2.0wt%, Hf: 0-0.2wt%, Zr: 0-0.2wt%, rare earth Y: 0.02-0.5wt%, rare earth La: 0.02-0.5wt%, Fe balance. In the microstructure of the rare earth strengthened high-chromium wear-resistant alloy: the carbides are dispersed and isolated in the grains and grain boundaries; the carbides include M7C3, M3C, M 23 C6, MC; the size of the carbides is 10-40 μm; in the microstructure of the rare earth strengthened high-chromium wear-resistant alloy: the volume fraction of the carbides is 48-55%.

2. The rare earth strengthened high chromium wear resistant alloy of claim 1, wherein, In the rare earth strengthened high chromium wear-resistant alloy, the mass ratio of C element to Cr element is 0.06-0.

18.

3. The rare earth strengthened high chromium wear resistant alloy of claim 1, wherein, The chemical composition of the rare earth strengthened high chromium wear-resistant alloy is, in mass percentage: C: 2.5-4.5wt%, Cr: 25-30wt%, Mo: 0.5-1.5wt%, Si: 0.5-1.0wt%, Mn: 0.2-1.0wt%, Nb: 0.01-0.05wt%, B: 0.01-0.05wt%, Ni: 0.5-2.0wt%, Ti: 0.2-1.0wt%, V: 0.2-1.0wt%, Hf: 0.1-0.2wt%, Zr: 0.1-0.2wt%, rare earth Y: 0.02-0.1wt%, rare earth La: 0.02-0.1wt%, Fe balance.

4. The rare earth strengthened high chromium wear resistant alloy of claim 1, wherein, The size of the carbide is 20-35μm.

5. The rare earth strengthened high chromium wear resistant alloy of claim 1, wherein, The size of the carbide is 30±2μm.

6. The rare earth strengthened high chromium wear resistant alloy of claim 1, wherein, The carbide is a rounded-edge carbide particle.

7. The rare earth strengthened high chromium wear resistant alloy of claim 1, wherein, The average grain size of the rare earth strengthened high chromium wear-resistant alloy is no more than 400μm.

8. The rare earth strengthened high chromium wear resistant alloy of claim 1, wherein, The hardness of the rare earth strengthened high chromium wear-resistant alloy is ≥HRC68, and the impact energy is more than 2.0 KV2 / J.

9. A method of producing a rare earth strengthened high chromium wear resistant alloy as claimed in any one of claims 1 to 8 characterised in that, It comprises the following steps: 1) Melting: the alloy raw material is subjected to melting treatment; wherein, the melting treatment process comprises high-temperature refining and low-temperature refining; 2) Casting: the alloy liquid after the melting treatment is subjected to casting treatment, to obtain an alloy ingot; 3) Heat treatment: the heat treatment process comprises the following steps in sequence: Gradient heat treatment: the alloy ingot is subjected to first heat treatment by being heated to 500-700℃ at a first heating rate, and after being kept for 2-3 hours, an alloy after the first heat treatment is obtained; the alloy after the first heat treatment is subjected to second heat treatment by being heated to 800-1000℃ at a second heating rate, and after being kept for 4-5 hours, an alloy after the second heat treatment is obtained; the alloy after the second heat treatment is subjected to third heat treatment by being heated to 1150-1180℃ at a third heating rate, and after being kept for 8-10 hours, the alloy is cooled to room temperature, to obtain an alloy after the third heat treatment; Subcritical heat treatment: the alloy after the third heat treatment is subjected to subcritical heat treatment by being heated to 400-500℃ at a fourth heating rate in a tempering furnace, and after being kept for 4-5 hours, a rare earth strengthened high chromium wear-resistant alloy is obtained.

10. The method of producing a rare earth strengthened high chromium wear resistant alloy according to claim 9, characterized in that, In the step 2), the casting process comprises ladle change casting.

11. The method of claim 9, wherein the rare earth strengthened high chromium wear-resistant alloy is prepared by the steps of: melting and smelting the alloying elements in a medium frequency induction furnace to obtain a molten alloy; refining the molten alloy at a high temperature and a low temperature; and casting the molten alloy. The first temperature rising rate is 50-100℃ / hour; and / or The second temperature rising rate is 50-100℃ / hour; and / or The third temperature rising rate is less than or equal to 50-100℃ / hour; and / or The fourth temperature rising rate is 50-100℃ / hour.

12. The method of producing a rare earth strengthened high chromium wear resistant alloy according to claim 9, characterized in that, In the step 1), the smelting treatment is performed in a medium frequency induction furnace.

13. The method of claim 9, wherein the rare earth strengthened high chromium wear-resistant alloy is prepared by the steps of: melting and smelting the alloying elements in a medium frequency induction furnace to obtain a molten alloy; refining the molten alloy at a high temperature and a low temperature; and casting the molten alloy. The high temperature refining is 1520-1550℃; and / or The low temperature refining is 1200-1300℃; and / or The casting temperature is 1450-1480℃.

14. The method of producing a rare earth strengthened high chromium wear resistant alloy according to claim 9, wherein, In the step 2), after the refining is completed, a deslagging agent is added to the molten alloy to adsorb sulfides and surface slag in the molten alloy, and the slag is gathered into a pile and then removed to reduce the impurity content of the alloy and ensure the cleanliness. The deslagging agent is expanded perlite sand.

15. The method of producing a rare earth strengthened high chromium wear resistant alloy according to claim 14, characterized in that, ​

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