Low-density high-aluminum high-manganese wear-resistant steel and casting forming method thereof

Abstract

The invention discloses low-density high-aluminum high-manganese wear-resistant steel and a casting forming method thereof.The casting forming method of the low-density high-aluminum high-manganese wear-resistant steel comprises the steps that Al and RE or Ce are added into manganese steel, the Mn content is adjusted, and the low-density high-aluminum high-manganese wear-resistant steel is obtained; casting a wear-resistant part by using the low-density high-aluminum high-manganese wear-resistant steel; carrying out water toughening treatment on the casting by adopting a stepped high-temperature austenitizing heat treatment process; and the casting subjected to water toughening treatment is subjected to aging treatment. According to the method, the Mn / C ratio is controlled to cooperate with the hardness and toughness indexes of the material, the material density is reduced to be smaller than or equal to 6.8 g / cm < 3 > by regulating and controlling the Mn / Al ratio, a casting method is adopted for forming, the cracking problem caused by rolling forming is avoided, forming of special-shaped complex components is facilitated, step austenitizing water toughening treatment is adopted, reasonable aging treatment is carried out, and the quality of the special-shaped complex components is improved. The grain size level of the casting is controlled to be greater than or equal to grade 2, and the matrix strength Rm of the casting is improved to be greater than or equal to 850Mpa.

Description

Technical Field

[0001] This invention belongs to the technical field of high manganese steel and its production process, specifically relating to a low-density, high-alumina, high-manganese wear-resistant steel and its casting method. Background Technology

[0002] Most wear-resistant parts in large mining excavators are made of high-manganese steel. However, traditional high-manganese steels such as ZGMn13 and ZGMn13Mo exhibit insufficient wear resistance and a short service life in low-impact abrasive wear. Furthermore, their density (≥7.85 g / cm³) also contributes to their wear. 3 However, high-manganese steel suffers from problems such as high weight, high energy consumption, and high operating costs. With ongoing research into improving the performance of traditional high-manganese steel, high-aluminum high-manganese steel has emerged. By adjusting the Mn content and adding a certain amount of Al, not only can the yield strength of the material at low temperatures be improved, but the density also decreases with increasing Al content. However, in existing technologies, increasing the Al content, for example, when Al > 5%, easily leads to grain boundary embrittlement, reducing material toughness, causing performance imbalance, and poor microstructural stability. Furthermore, adjusting the Mn content too low, for example, when Mn ≤ 15%, weakens work hardening ability, resulting in insufficient wear resistance under low-impact conditions. In addition, high-aluminum high-manganese steel products are typically formed by rolling, and rolling cracking is common. Moreover, the rolling process struggles to suppress Al oxidation, leading to excessive oxide levels, which affects the mechanical and performance properties of wear-resistant parts. Therefore, there is an urgent need to develop a new type of high-aluminum high-manganese wear-resistant steel that combines ultra-low density, high wear resistance, and stable toughness. Summary of the Invention

[0003] To address some or all of the technical problems existing in the prior art, the present invention provides a low-density, high-alumina, high-manganese wear-resistant steel and its casting method.

[0004] In a first aspect of the invention, a low-density, high-alumina, high-manganese wear-resistant steel is provided, wherein the chemical composition of the low-density, high-alumina, high-manganese wear-resistant steel is controlled by mass percentage as follows: C: 0.9-1.35%, Mn: 28.0-31.0%, Al: 8.0-10.0%, Si≤0.4%, P≤0.03%, S≤0.02%, with the remainder being Fe and unavoidable impurities, wherein the Mn / C ratio is controlled to be less than 35, and the Mn / Al ratio is controlled to be between 2.8 and 4.0.

[0005] Furthermore, the aforementioned low-density, high-aluminum, high-manganese wear-resistant steel also includes RE or Ce with a mass percentage content of 0.3% to 0.5%.

[0006] In a second aspect of the present invention, a method for casting low-density, high-aluminum, high-manganese wear-resistant steel is provided, comprising the following steps:

[0007] Preparation: Al and RE or Ce are added to manganese steel and the Mn content is adjusted to obtain low-density high-alumina high-manganese wear-resistant steel. The chemical composition of the low-density high-alumina high-manganese wear-resistant steel is controlled by mass percentage as follows: C: 0.9-1.35%, Mn: 28.0-31.0%, Al: 8.0-10.0%, Si≤0.4%, P≤0.03%, S≤0.02%, RE or Ce: 0.3-0.5%, with the remainder being Fe and unavoidable impurities. The Mn / C ratio is controlled to be less than 35, and the Mn / Al ratio is controlled to be 2.8-4.0.

[0008] Casting: Wear-resistant parts are cast using the aforementioned low-density, high-alumina, high-manganese wear-resistant steel;

[0009] Water quenching treatment of castings: The castings are water quenched using a stepped high-temperature austenitizing heat treatment process. First, the castings are heated to 960-980℃ at a heating rate of ≤40℃ / h and held for 4-6 hours. Then, the castings are heated to 1120-1140℃ and held for 2 hours. Finally, the castings are water cooled.

[0010] Aging treatment of castings: After water quenching, the castings are subjected to aging treatment by heating the castings to 480-500℃, holding them at that temperature for 2 hours, and then air cooling the castings to room temperature.

[0011] Furthermore, in the casting steps of the above-mentioned low-density, high-alumina, high-manganese wear-resistant steel casting method, the molding method of mold frame + sample + core is adopted for pouring. The gating system is set as fully open, and the gating area is set according to ΣF_ladle: ΣF_straight: ΣF_inner = 1:2:4, where ΣF_ladle, ΣF_straight, and ΣF_inner are the total cross-sectional areas of the ladle hole, the total cross-sectional area of ​​the sprue, and the total cross-sectional area of ​​the ingate, respectively.

[0012] Furthermore, in the casting water quenching step of the above-mentioned low-density high-alumina high-manganese wear-resistant steel casting forming method, the water temperature of the casting is controlled at ≤37℃ throughout the water cooling process.

[0013] As one implementation method, the above-mentioned low-density high-alumina high-manganese wear-resistant steel casting method is applied to the casting of bucket teeth for mining excavators. In the casting process, an external chill is set in the tooth tip area of ​​the bucket tooth casting and chromite face sand is used for rapid cooling. The gating system is set to introduce molten steel from the edge of the hot spot at the tooth tip at the parting surface of the casting. A necking riser is set opposite the external chill in the tooth tip area for concentrated feeding.

[0014] Compared with the prior art, the low-density high-alumina high-manganese wear-resistant steel and its casting method of the present invention have the following advantages and beneficial effects:

[0015] This invention achieves synergistic effects between the hardness and toughness of the material by controlling the Mn / C ratio, and reduces the material density to ≤6.8 g / cm³ by adjusting the Mn / Al ratio. 3Optimize the work hardening ability of materials;

[0016] This invention uses a casting method to form the components, avoiding the cracking problems caused by rolling, and facilitating the forming of irregular and complex components.

[0017] This invention optimizes the casting process by employing a stepped austenitizing water toughening treatment and reasonable aging treatment to solve the problem of nozzle formation during the casting process, control the grain size level of the casting's service parts to ≥2, and improve the casting matrix strength to Rm≥850Mpa. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a mining excavator bucket tooth, which serves as an application example of the casting and forming method of the novel low-density high-aluminum high-manganese wear-resistant steel of the present invention.

[0020] Figure 2 This is a process sequence diagram of the water toughening treatment of castings in the novel low-density, high-aluminum, high-manganese wear-resistant steel casting forming method of the present invention;

[0021] Figure 3 This is a process sequence diagram of the casting aging treatment in the novel low-density, high-alumina, high-manganese wear-resistant steel casting forming method of the present invention;

[0022] Figure 4 These are TEM images of the microstructure of the casting matrix after aging treatment;

[0023] Figure 5 It is an electron diffraction pattern of κ carbides in the microstructure of the casting after aging treatment. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] To address the problems of poor microstructural stability, immature rolling-based manufacturing methods, and insufficient wear resistance under low-impact conditions in existing high-aluminum, high-manganese steel, this invention develops a novel high-aluminum, high-manganese wear-resistant steel and its casting method that combines ultra-low density, high wear resistance, and stable toughness. The main technical measures of this invention include: controlling the Mn / C ratio and Mn / Al ratio based on the alloy strengthening mechanism of the material, and using a casting method to manufacture the high-aluminum, high-manganese wear-resistant steel product. Thus, while reducing the density of the manganese steel material, the impact hardening ability is optimized, the product performance is improved, the product service life is extended, and the product energy consumption is reduced, enabling long-life, low-cost, and low-energy-consumption applications of wear-resistant parts for large mining excavators.

[0026] The chemical composition of the low-density, high-alumina, high-manganese wear-resistant steel of the present invention is controlled by mass percentage as follows: C: 0.9-1.35%, Mn: 28.0-31.0%, Al: 8.0-10.0%, Si≤0.4%, P≤0.03%, S≤0.02%, with the remainder being Fe and unavoidable impurities. The Mn / C ratio is controlled to be less than 35, and the Mn / Al ratio is controlled to be between 2.8 and 4.0.

[0027] As described above, the low-density high-alumina high-manganese wear-resistant steel of the present invention is made by adding Al element to manganese steel and adjusting the Mn element content, controlling the Mn / C ratio to be less than 35, so as to synergize the hardness and toughness index of the material, and controlling the Mn / Al ratio between 2.8 and 4.0. By controlling the precise ratio of Mn and Al elements, the material density is reduced while the work hardening ability is optimized, thereby forming a new type of high-alumina high-manganese wear-resistant cast steel, which improves the mechanical and service performance of the corresponding wear-resistant castings.

[0028] Preferably, the low-density high-alumina high-manganese wear-resistant steel of the present invention may further include RE or Ce with a mass percentage content of 0.3-0.5%, preferably 0.4%, to modify and purify the material of the high-alumina high-manganese wear-resistant steel. While improving the type, shape, distribution, quantity and size of inclusions in the product, it also improves casting fluidity, thereby improving the cleanliness, grain size level and casting filling ability of the casting product.

[0029] The casting and forming method for low-density, high-alumina, high-manganese wear-resistant steel of the present invention includes the following steps:

[0030] (I) Material preparation

[0031] By adding Al and RE or Ce to manganese steel and adjusting the Mn content, a low-density high-alumina high-manganese wear-resistant steel is obtained. The chemical composition of this low-density high-alumina high-manganese wear-resistant steel is controlled by mass percentage as follows: C: 0.9-1.35%, Mn: 28.0-31.0%, Al: 8.0-10.0%, Si≤0.4%, P≤0.03%, S≤0.02%, RE or Ce: 0.3-0.5%, with the remainder being Fe and unavoidable impurities. The Mn / C ratio is controlled to be less than 35, and the Mn / Al ratio is controlled to be 2.8-4.0.

[0032] (II) Casting

[0033] Wear-resistant parts are cast using the aforementioned low-density, high-alumina, and high-manganese wear-resistant steel. The casting process employs a mold frame + sample + core casting method. To ensure the liquid filling capacity of the high-alumina and high-manganese steel, the gating system is set to be fully open with a large open ratio. Specifically, the gating area is set according to ΣF_bottle: ΣF_straight: ΣF_inner = 1:2:4, where ΣF_bottle, ΣF_straight, and ΣF_inner are the total cross-sectional areas of the ladle holes, the sprue, and the ingate, respectively.

[0034] As one specific implementation method, to cast such as Figure 1 Taking the typical wear-resistant bucket teeth of a mining excavator as an example, in the casting steps of the low-density high-alumina high-manganese wear-resistant steel casting method of the present invention, the tooth tip area of ​​the bucket tooth casting is chilled by setting an external chill and using chromite face sand to achieve directional solidification of the casting. While increasing the pouring temperature to solve the problem of nozzle nodules caused by high Al content, the grain size and density level of the tooth tip area are controlled to ensure the wear resistance of the bucket tooth casting during use. In addition, the gating system is set to introduce molten steel from the edge of the hot spot at the tooth tip at the parting surface of the casting to improve the degree of turbulence of the molten steel during filling. A necking heating riser is set opposite the external chill in the tooth tip area for centralized feeding. While avoiding shrinkage defects in the ingate, the cold collision removal of the casting riser is achieved, avoiding the gas cutting crack problem caused by cutting removal.

[0035] (III) Water toughening treatment of castings

[0036] Water toughening of castings is performed using a stepped high-temperature austenitizing heat treatment process, such as... Figure 2 As shown, the casting is first heated to 960-980℃ at a heating rate of ≤40℃ / h and held for 4-6 hours. Then, the casting is heated to 1120-1140℃ and held for 2 hours. Finally, the casting is water-cooled, and the water temperature is controlled to be ≤37℃ throughout the water-cooling process.

[0037] In the water toughening process of castings, the first stage of high-temperature austenitizing heat treatment (960–980℃, holding for 4–6 hours) promotes the decomposition, dissolution, and diffusion of grain boundary κ carbides (Fe·Mn)3AlC. Then, the second stage of high-temperature austenitizing heat treatment (1120–1140℃, holding for 2 hours) further enhances the diffusion capacity of κ carbides, ensuring homogenization of high-temperature austenite. Therefore, this step-by-step high-temperature austenitizing heat treatment process for castings not only ensures sufficient dissolution and diffusion of κ carbides but also mitigates austenite grain coarsening caused by prolonged temperature and time, effectively controlling the grain size of the casting.

[0038] (iv) Aging treatment of castings

[0039] Aging treatment is performed on castings that have undergone water toughening, such as... Figure 3 As shown, the casting is heated to 480-500℃, held at that temperature for 2 hours, and then air-cooled to room temperature.

[0040] Aging treatment of castings allows for dispersion strengthening of the casting matrix using κ carbides, thereby improving the matrix's strength. See the TEM image of the microstructure of the casting matrix after aging treatment. Figure 4 For the distribution of κ carbide morphology in the microstructure of the casting after aging treatment, please refer to [reference needed]. Figure 5 .

[0041] Actual production testing has shown that, through implementing the low-density high-alumina high-manganese wear-resistant steel and its casting method of this invention, the material density of the high-alumina high-manganese wear-resistant steel is ≤6.8 g / cm³. 3 The casting grain size is ≥2, and the casting matrix strength Rm is ≥850Mpa, which fully meets the performance and usage requirements of wear-resistant parts for large mining excavators.

[0042] In summary, this invention optimizes the work hardening ability of the material by controlling the Mn / C ratio to synergistically improve the hardness and toughness of the material, reducing the material density by adjusting the Mn / Al ratio, and employing a casting method to avoid cracking problems caused by rolling, thus facilitating the forming of complex and irregularly shaped components. Furthermore, by optimizing the casting process, employing step-austenitic water toughening treatment and appropriate aging treatment, this invention solves the problem of nozzle formation during the casting process, controls the grain size level of the application area of ​​the casting, and improves the matrix strength of the casting. Therefore, compared with existing technologies, this invention develops a novel high-alumina, high-manganese wear-resistant steel and its casting method that combine ultra-low density, high wear resistance, and stable toughness. While reducing the density of manganese steel, it optimizes impact hardening ability, improves product performance, extends product lifespan, and reduces energy consumption, enabling long-life, low-cost, and low-energy-consumption applications of wear-resistant parts for large mining excavators.

[0043] It should be noted that, in this document, the term "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device.

[0044] It should also be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the present invention.

Claims

1. A low-density, high-alumina, high-manganese wear-resistant steel, characterized in that, The chemical composition of the low-density, high-alumina, high-manganese wear-resistant steel is controlled by mass percentage as follows: C: 0.9-1.35%, Mn: 28.0-31.0%, Al: 8.0-10.0%, Si≤0.4%, P≤0.03%, S≤0.02%, with the remainder being Fe and unavoidable impurities. The Mn / C ratio is controlled to be less than 35, and the Mn / Al ratio is controlled to be between 2.8 and 4.

0.

2. The low-density, high-alumina, high-manganese wear-resistant steel as described in claim 1, characterized in that, The low-density, high-alumina, high-manganese wear-resistant steel also includes RE or Ce at a mass percentage of 0.3 to 0.5%.

3. A method for casting and forming low-density, high-alumina, high-manganese wear-resistant steel, characterized in that, Includes the following steps: Preparation: Al and RE or Ce are added to manganese steel and the Mn content is adjusted to obtain low-density high-alumina high-manganese wear-resistant steel. The chemical composition of the low-density high-alumina high-manganese wear-resistant steel is controlled by mass percentage as follows: C: 0.9-1.35%, Mn: 28.0-31.0%, Al: 8.0-10.0%, Si≤0.4%, P≤0.03%, S≤0.02%, RE or Ce: 0.3-0.5%, with the remainder being Fe and unavoidable impurities. The Mn / C ratio is controlled to be less than 35, and the Mn / Al ratio is controlled to be 2.8-4.

0. Casting: Wear-resistant parts are cast using the aforementioned low-density, high-alumina, high-manganese wear-resistant steel; Water quenching treatment of castings: The castings are water quenched using a stepped high-temperature austenitizing heat treatment process. First, the castings are heated to 960-980℃ at a heating rate of ≤40℃ / h and held for 4-6 hours. Then, the castings are heated to 1120-1140℃ and held for 2 hours. Finally, the castings are water cooled. Aging treatment of castings: After water quenching, the castings are subjected to aging treatment by heating the castings to 480-500℃, holding them at that temperature for 2 hours, and then air cooling the castings to room temperature.

4. The casting and forming method for low-density, high-alumina, high-manganese wear-resistant steel as described in claim 3, characterized in that, In the casting process, the molding method of mold frame + sample + core is used for pouring. The gating system is set to be fully open. The gating area is set according to ΣF_bottle: ΣF_straight: ΣF_inner = 1:2:4, where ΣF_bottle, ΣF_straight, and ΣF_inner are the total cross-sectional areas of the ladle hole, the total cross-sectional area of ​​the sprue, and the total cross-sectional area of ​​the ingate, respectively.

5. The casting and forming method for low-density, high-alumina, high-manganese wear-resistant steel as described in claim 3, characterized in that, During the water toughening process of castings, the water temperature is controlled at ≤37℃ throughout the entire water cooling process.

6. The casting and forming method for low-density, high-alumina, high-manganese wear-resistant steel as described in any one of claims 3 to 5, characterized in that, The low-density, high-alumina, high-manganese wear-resistant steel casting method is applied to the casting of bucket teeth for mining excavators. In the casting process, an external chill is set in the tooth tip area of ​​the bucket tooth casting and chromite face sand is used for rapid cooling. The gating system is set to introduce molten steel from the edge of the hot spot at the tooth tip at the parting surface of the casting. A necking riser is set opposite the external chill in the tooth tip area for concentrated feeding.

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