Low-density wear-resistant high-chromium cast iron and preparation method thereof

Abstract

This invention provides a low-density wear-resistant high-chromium cast iron and its preparation method, relating to the technical field of metal material design and heat treatment. The chemical composition of the low-density wear-resistant high-chromium cast iron, by mass percentage, is: C 3.16-3.22%, Si 0.4-0.6%, Mn 12.7-13.3%, Cr 19.0-20.0%, Cu 0.8-1.1%, Mo 0.9-1.0%, V 0.10-0.14%, Ti 0.04-0.07%, Al 5.7-6.3%, with the remainder being Fe and other unavoidable impurities. The preparation method of the low-density wear-resistant high-chromium cast iron includes quenching treatment, cryogenic treatment, and tempering treatment. This invention reduces the density of cast iron from the high density of traditional high-chromium cast iron to a low density by introducing Al and Mn elements, thus achieving the low-density characteristics of wear-resistant cast iron. It also creatively introduces deep cryogenic treatment between the quenching and tempering processes, synergistically optimizing the precipitation morphology and distribution of carbides in the microstructure, significantly improving the material's hardness. This method is stable, easy to operate, and suitable for applications such as mining machinery and engineering machinery where both material weight and wear resistance are critical.

Description

Technical Field

[0001] This invention relates to the technical field of metal material design and heat treatment, and in particular to a low-density wear-resistant high-chromium cast iron and its preparation method. Background Technology

[0002] High-chromium cast iron, containing a large amount of chromium (Cr), forms extremely hard M7C3 type carbides during solidification, exhibiting both excellent wear resistance and a certain degree of toughness. It is widely used in the manufacture of wear-resistant components such as crusher hammers, liners, and conveying pipes. However, the density of traditional high-chromium cast iron is typically between 7.5 and 7.8 g / cm³. In applications requiring lightweight equipment, this higher density increases energy consumption and operating load, limiting its application range.

[0003] To reduce the density of high-chromium cast iron, existing technologies often employ the addition of lightweight elements such as Al and Mg. However, this approach frequently presents several problems: Firstly, the amount of lightweight elements added is difficult to control precisely, while excessive addition can significantly reduce the toughness and wear resistance of the cast iron. Secondly, lightweight elements readily form brittle intermetallic compounds with other elements, affecting the stability of the material's mechanical properties. Furthermore, current heat treatment processes for high-chromium cast iron primarily employ the conventional combination of quenching and tempering. While this improves the toughness of the microstructure, it limits the potential for increased hardness, making it unsuitable for certain applications. Some processes attempt to lower the tempering temperature to increase hardness, but low-temperature tempering results in significant residual stress, making the material prone to cracking during use, thus compromising both hardness and safety.

[0004] Chinese patent CN104109798A discloses a high-chromium wear-resistant cast iron steel ball. The chemical composition of this steel ball contains a variety of alloying elements. Although lightweight elements are added, the amount added is not large, and the problem of high density in traditional high-chromium cast iron is not solved. Moreover, the water quenching and tempering treatments in its preparation method limit the hardness improvement and easily lead to stress residue. At the same time, this material is only suitable for a single steel ball product, which limits the application scenarios. It is difficult to accurately control the amount of alloying elements added, making it difficult to achieve synergistic optimization of comprehensive performance.

[0005] Chinese patent CN116083785A discloses a wear-resistant high-chromium cast iron and its preparation method, but it does not introduce lightweight elements, and the material density is still at the level of traditional high-chromium cast iron, which cannot meet the requirements for lightweighting. Moreover, it only adopts the conventional annealing + quenching + low-temperature tempering process without any strengthening auxiliary means, which limits the improvement of hardness and makes it easy for residual stress to cause cracking during low-temperature tempering.

[0006] Chinese patent CN102899468A discloses a heat treatment method for high-chromium wear-resistant white cast iron Cr28, but it only optimizes the heat treatment process for Cr28 cast iron without introducing lightweight elements. The material density remains at the level of traditional high-chromium cast iron, which cannot meet the requirements for lightweighting. Moreover, its heat treatment process is only designed to improve machinability without targeted optimization of carbide morphology and distribution, and there are no strengthening auxiliary processes. The hardness improvement relies solely on quenching + secondary low-temperature tempering, which does not solve the problem of limited hardness improvement in traditional processes.

[0007] Chinese patent CN121109859A discloses a wear-resistant and high-toughness high-chromium cast iron material and its preparation method, but it does not add light alloying elements such as Al, and the material lacks low-density characteristics, failing to solve the core problem of the high density of traditional high-chromium cast iron. Moreover, its melting temperature is as high as 1520~1550℃, and the heating rate of heat treatment and tempering treatment is slow, the process is cumbersome, the production energy consumption is high and the efficiency is low, which is not conducive to large-scale industrial promotion. Although it achieves high hardness and high toughness through composition adjustment and secondary heating, it does not make targeted optimizations to the morphology and distribution of carbide precipitation, nor does it have any strengthening auxiliary processes, and it has not broken through the performance optimization bottleneck of traditional heat treatment.

[0008] Therefore, there is an urgent need to develop a high-chromium cast iron with a reasonable composition design, significantly reduced density, and a substantial increase in hardness achieved by introducing deep cryogenic treatment between quenching and tempering, as well as its preparation method. This is the key to solving the bottleneck of existing technology and has important industrial application value. Summary of the Invention

[0009] The main objective of this invention is to address the technical problems of high density and limited hardness improvement in existing high-chromium cast iron due to conventional heat treatment processes. Therefore, this invention proposes a low-density, wear-resistant high-chromium cast iron, its preparation method, and a preparation technique that can solve the aforementioned problems.

[0010] A low-density wear-resistant high-chromium cast iron, wherein the chemical composition of the low-density wear-resistant high-chromium cast iron, by mass percentage, is: C 3.16-3.22%, Si 0.4-0.6%, Mn 12.7-13.3%, Cr 19.0-20.0%, Cu 0.8-1.1%, Mo 0.9-1.0%, V 0.10-0.14%, Ti 0.04-0.07%, Al 5.7-6.3%, with the remainder being Fe and other unavoidable impurities; the preparation method of the low-density wear-resistant high-chromium cast iron includes quenching treatment, cryogenic treatment, and tempering treatment.

[0011] Optionally, the microstructure of the low-density wear-resistant high-chromium cast iron is 45% martensite matrix, 10% retained austenite, and 45% M7C3 type carbide, wherein the M7C3 type carbide is blocky with a size of 60-80 μm, and the retained austenite is 5-8 μm.

[0012] Optionally, the density of the low-density wear-resistant high-chromium cast iron is 6.98-7.02 g / cm³. 3 Compared to traditional high-chromium cast iron, its density is reduced by 8.12-8.64%; its hardness is 53.5-55.5 HRC, and its impact toughness is 1.16-1.19 J / cm². 2 .

[0013] A method for preparing the low-density wear-resistant high-chromium cast iron, comprising the following preparation steps:

[0014] S1. Melting and casting: Weigh and melt the raw materials according to the composition ratio of the low-density wear-resistant high-chromium cast iron, and then cast the high-chromium cast iron at high temperature to obtain the high-chromium cast iron.

[0015] S2. Quenching treatment: After cutting the high-chromium cast iron of S1, heat it in a heating furnace and keep it at a certain temperature. Then, place the high-chromium cast iron in air or quenching oil for quenching treatment to obtain quenched high-chromium cast iron.

[0016] S3, cryogenic treatment: The quenched high-chromium cast iron of S2 is subjected to cryogenic treatment. The cryogenically treated high-chromium cast iron is placed in air to be warmed to room temperature to obtain cryogenic high-chromium cast iron.

[0017] S4. Tempering treatment: The deep cryogenic high-chromium cast iron of S3 is heated and held at a temperature in a heating furnace for tempering treatment. The tempered high-chromium cast iron is then placed in air and cooled to room temperature to obtain tempered low-density wear-resistant cast iron.

[0018] Optionally, during the quenching treatment of S2 high-chromium cast iron, the heating rate shall not exceed 10°C / min, the holding temperature shall be 1050-1250°C, and the holding time shall be 2h.

[0019] Optionally, the cryogenic treatment in S3 is performed at a temperature of -196°C (liquid nitrogen) for 1 hour.

[0020] Optionally, during the tempering process in S4, the heating rate does not exceed 10°C / min, the tempering temperature is 250-450°C, and the tempering time is 2 hours.

[0021] Optionally, the preparation method of the low-density wear-resistant high-chromium cast iron further includes performance measurement: it is necessary to perform multi-point performance measurements on the high-chromium cast iron of S1 and the tempered low-density wear-resistant cast iron of S4, and finally calculate the average value as the performance value of the material.

[0022] Optionally, the multi-point performance measurement is selected at the riserless part of the material, the center, and at a point 1 / 4 of the thickness from the edge.

[0023] Technical principle of the invention:

[0024] Cryogenic treatment, as an auxiliary process for strengthening metallic materials, significantly improves the hardness and wear resistance of materials by promoting the transformation of retained austenite to martensite and refining carbide particles at low temperatures. Currently, cryogenic treatment has been applied in tool steel and die steel, but research on combining it with the "quenching + tempering" process of high-chromium cast iron to synergistically improve the hardness of low-density high-chromium cast iron has not been reported, nor has a mature industrial-scale manufacturing technology been developed.

[0025] This invention reduces the hardness of wear-resistant cast iron by introducing Al and Mn elements, and introduces deep cryogenic treatment on the basis of the traditional "quenching + tempering" process to further improve the transformation of retained austenite to martensite, obtain more martensite, and further improve the hardness of wear-resistant cast iron.

[0026] The above technical solution has at least the following advantages compared with the existing technology:

[0027] The above-mentioned solution proposes a low-density wear-resistant high-chromium cast iron and its preparation method, which can solve the technical problems of high density and limited hardness improvement of existing high-chromium cast iron by conventional heat treatment processes.

[0028] This invention reduces the density of cast iron from the high density of traditional high-chromium cast iron to a low density by introducing Al and Mn elements, thus achieving the low-density characteristics of wear-resistant cast iron.

[0029] This invention enables the complete transformation of ferrite into austenite by quenching high-chromium cast iron, and further transforms some of the austenite into martensite by air cooling.

[0030] This invention enables the residual austenite to be further transformed into martensite by deep cryogenic treatment of quenched high-chromium cast iron, thereby further improving the hardness of wear-resistant cast iron.

[0031] This invention releases internal stress and repairs internal microcracks by tempering cryogenic high-chromium cast iron, thereby causing the cast iron to undergo secondary hardening.

[0032] The method of this invention is stable and easy to operate. The cast iron prepared has low density, high hardness and excellent wear resistance, and is suitable for mining machinery, engineering machinery and other fields where both material weight and wear resistance are required.

[0033] In summary, compared with existing methods for preparing high-chromium cast iron, the method of this invention controls the microstructure by quenching, cryogenic treatment and tempering of high-chromium cast iron, thereby achieving synergistic optimization of hardness and density. This method is simple in process, easy to operate, environmentally friendly, low in cost and high in efficiency, and is conducive to large-scale industrial production and application. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0035] Figure 1 This is a schematic diagram of the process for preparing a low-density, wear-resistant, high-chromium cast iron according to the present invention.

[0036] Figure 2 This is a TC simulation diagram of a low-density wear-resistant high-chromium cast iron according to the present invention, which provides a reference for the selection of heat treatment temperature range in Examples 1-3;

[0037] Figure 3 This is a comparison chart of the hardness of high-chromium cast iron under different heat treatment processes in the preparation method of low-density wear-resistant high-chromium cast iron of the present invention. Detailed Implementation

[0038] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0039] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0040] In the embodiments of the present invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that when the distinction is not emphasized, their intended meanings are consistent.

[0041] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0042] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0043] A low-density wear-resistant high-chromium cast iron, wherein the chemical composition of the low-density wear-resistant high-chromium cast iron, by mass percentage, is: C 3.16-3.22%, Si 0.4-0.6%, Mn 12.7-13.3%, Cr 19.0-20.0%, Cu 0.8-1.1%, Mo 0.9-1.0%, V 0.10-0.14%, Ti 0.04-0.07%, Al 5.7-6.3%, with the remainder being Fe and other unavoidable impurities; the preparation method of the low-density wear-resistant high-chromium cast iron includes quenching treatment, cryogenic treatment, and tempering treatment.

[0044] Specifically, the microstructure of the low-density wear-resistant high-chromium cast iron consists of a martensitic matrix with a volume fraction of 45%, a retained austenite with a volume fraction of 10%, and M7C3 type carbides with a volume fraction of 45%, wherein the M7C3 type carbides are blocky with a size of 60-80 μm, and the retained austenite has a size of 5-8 μm.

[0045] Specifically, the density of the low-density wear-resistant high-chromium cast iron is 6.98-7.02 g / cm³. 3 Compared to traditional high-chromium cast iron, its density is reduced by 8.12-8.64%; its hardness is 53.5-55.5 HRC, and its impact toughness is 1.16-1.19 J / cm². 2 .

[0046] A method for preparing low-density wear-resistant high-chromium cast iron, wherein the method for preparing low-density wear-resistant high-chromium cast iron is combined with... Figure 1 The preparation steps include the following:

[0047] S1. Melting and casting: Weigh and melt the raw materials according to the composition ratio of the low-density wear-resistant high-chromium cast iron, and then cast the high-chromium cast iron at high temperature to obtain the high-chromium cast iron.

[0048] S2. Quenching treatment: After cutting the high-chromium cast iron of S1, heat it in a heating furnace and keep it at a certain temperature. Then, place the high-chromium cast iron in air or quenching oil for quenching treatment to obtain quenched high-chromium cast iron.

[0049] S3, cryogenic treatment: The quenched high-chromium cast iron of S2 is subjected to cryogenic treatment. The cryogenically treated high-chromium cast iron is placed in air to be warmed to room temperature to obtain cryogenic high-chromium cast iron.

[0050] S4. Tempering treatment: The deep cryogenic high-chromium cast iron of S3 is heated and held at a temperature in a heating furnace for tempering treatment. The tempered high-chromium cast iron is then placed in air and cooled to room temperature to obtain tempered low-density wear-resistant cast iron.

[0051] Specifically, during the quenching treatment of S2 high-chromium cast iron, the heating rate should not exceed 10°C / min, the holding temperature should be 1050-1250°C, and the holding time should be 2 hours.

[0052] Specifically, the cryogenic treatment in S3 is performed at a temperature of -196°C (liquid nitrogen) for 1 hour.

[0053] Specifically, during the tempering process in S4, the heating rate does not exceed 10°C / min, the tempering temperature is 250-450°C, and the tempering time is 2 hours.

[0054] In particular, the preparation method of the low-density wear-resistant high-chromium cast iron also includes performance measurement: it is necessary to perform multi-point performance measurements on the high-chromium cast iron of S1 and the tempered low-density wear-resistant cast iron of S4, and finally calculate the average value as the performance value of the material.

[0055] Specifically, the multi-point performance measurement is performed at the riserless section, the center, and at a point 1 / 4 of the thickness from the edge of the material.

[0056] Example 1

[0057] This embodiment discloses a low-density wear-resistant high-chromium cast iron. The chemical composition of the low-density wear-resistant high-chromium cast iron, by mass percentage, is: C 3.19%, Si 0.53%, Mn 12.84%, Cr 19.96%, Cu 0.99%, Mo 0.94%, V 0.12%, Ti 0.051%, Al 5.71%, with the remainder being Fe and other unavoidable impurities. The preparation method of the low-density wear-resistant high-chromium cast iron includes quenching treatment and tempering treatment.

[0058] A method for preparing low-density wear-resistant high-chromium cast iron, wherein the method for preparing low-density wear-resistant high-chromium cast iron is combined with... Figure 1 The preparation steps include the following:

[0059] S1. Melting and Casting: The raw materials are weighed and melted according to the composition ratio of the low-density wear-resistant high-chromium cast iron, and then cast at high temperature to obtain high-chromium cast iron; the density of the high-chromium cast iron is 7.0 g / cm³. 3 Compared to traditional high-chromium cast iron, its density is reduced by approximately 8.32%; its hardness is 54.2 HRC, and its impact toughness is 1.17 J / cm². 2 ;

[0060] S2. Quenching treatment: Cut the high-chromium cast iron of S1, heat it in a heating furnace at a heating rate not exceeding 10°C / min, hold it at 1150°C for 2 hours, and then place the high-chromium cast iron after holding it in air or quenching oil for quenching treatment to obtain quenched high-chromium cast iron.

[0061] S3. Cryogenic treatment: The quenched high-chromium cast iron of S2 is subjected to cryogenic treatment at a temperature of -196°C liquid nitrogen for 1 hour. The cryogenically treated high-chromium cast iron is then placed in air to warm up to room temperature to obtain cryogenic high-chromium cast iron.

[0062] S4. Tempering treatment: The deep cryogenic high-chromium cast iron of S3 is heated and held in a heating furnace for tempering treatment. The heating rate during tempering treatment shall not exceed 10°C / min, the tempering temperature is 450°C, and the tempering time is 2h. The tempered high-chromium cast iron is placed in air to cool to room temperature to obtain tempered low-density wear-resistant cast iron.

[0063] The preparation method of low-density wear-resistant high-chromium cast iron described in this embodiment also includes performance measurement: it is necessary to perform multi-point performance measurements on S1 high-chromium cast iron and S4 tempered low-density wear-resistant cast iron, and finally calculate the average value as the performance value of the material.

[0064] The multi-point performance measurement is performed at the riserless part of the material, the center, and at a point 1 / 4 of the thickness from the edge.

[0065] In a comparison of the properties of high-chromium cast iron S1 and tempered low-density wear-resistant cast iron S4, the density did not change significantly, but the hardness became 52.4 HRC and the impact toughness became 2.37 J.

[0066] Example 2

[0067] This embodiment discloses a low-density wear-resistant high-chromium cast iron. The chemical composition of the low-density wear-resistant high-chromium cast iron, by mass percentage, is: C 3.19%, Si 0.49%, Mn 12.89%, Cr 19.83%, Cu 1.01%, Mo 0.98%, V 0.12%, Ti 0.063%, Al 6.03%, with the remainder being Fe and other unavoidable impurities. The preparation method of the low-density wear-resistant high-chromium cast iron includes quenching treatment and tempering treatment.

[0068] A method for preparing low-density wear-resistant high-chromium cast iron, wherein the method for preparing low-density wear-resistant high-chromium cast iron is combined with... Figure 1 The preparation steps include the following:

[0069] S1. Melting and Casting: The raw materials are weighed and melted according to the composition ratio of the low-density wear-resistant high-chromium cast iron, and then cast at high temperature to obtain high-chromium cast iron; the density of the high-chromium cast iron is 7.01 g / cm³. 3 Compared to traditional high-chromium cast iron, its density is reduced by approximately 8.32%; its hardness is 55.2 HRC, and its impact toughness is 1.16 J / cm². 2 ;

[0070] S2. Quenching treatment: Cut the high-chromium cast iron of S1, heat it in a heating furnace at a rate not exceeding 10°C / min, hold it at 1200°C for 2 hours, and then quench the high-chromium cast iron in air or quenching oil to obtain quenched high-chromium cast iron.

[0071] S3. Cryogenic treatment: The quenched high-chromium cast iron of S2 is subjected to cryogenic treatment at a temperature of -196°C liquid nitrogen for 1 hour. The cryogenically treated high-chromium cast iron is then placed in air to warm up to room temperature to obtain cryogenic high-chromium cast iron.

[0072] S4. Tempering treatment: The deep cryogenic high-chromium cast iron of S3 is heated and held in a heating furnace for tempering treatment. The heating rate during tempering treatment shall not exceed 10°C / min, the tempering temperature is 450°C, and the tempering time is 2h. The tempered high-chromium cast iron is placed in air to cool to room temperature to obtain tempered low-density wear-resistant cast iron.

[0073] The preparation method of low-density wear-resistant high-chromium cast iron described in this embodiment also includes performance measurement: it is necessary to perform multi-point performance measurements on S1 high-chromium cast iron and S4 tempered low-density wear-resistant cast iron, and finally calculate the average value as the performance value of the material.

[0074] The multi-point performance measurement is performed at the riserless part of the material, the center, and at a point 1 / 4 of the thickness from the edge.

[0075] In a comparison of the properties of high-chromium cast iron S1 and tempered low-density wear-resistant cast iron S4, the density did not change significantly, but the hardness became 53.9 HRC and the impact toughness became 2.32 J.

[0076] Example 3

[0077] This embodiment discloses a low-density wear-resistant high-chromium cast iron. The chemical composition of the low-density wear-resistant high-chromium cast iron, by mass percentage, is: C 3.20%, Si 0.51%, Mn 13.07%, Cr 19.97%, Cu 1.08%, Mo 0.92%, V 0.11%, Ti 0.054%, Al 6.21%, with the remainder being Fe and other unavoidable impurities. The preparation method of the low-density wear-resistant high-chromium cast iron includes quenching treatment and tempering treatment.

[0078] A method for preparing low-density wear-resistant high-chromium cast iron, wherein the method for preparing low-density wear-resistant high-chromium cast iron is combined with... Figure 1 The preparation steps include the following:

[0079] S1. Melting and Casting: The raw materials are weighed and melted according to the composition ratio of the low-density wear-resistant high-chromium cast iron, and then cast at high temperature to obtain high-chromium cast iron; the density of the high-chromium cast iron is 6.99 g / cm³.3 Compared to traditional high-chromium cast iron, its density is reduced by approximately 8.32%; its hardness is 53.8 HRC, and its impact toughness is 1.19 J / cm². 2 ;

[0080] S2. Quenching treatment: Cut the high-chromium cast iron of S1, heat it in a heating furnace at a heating rate not exceeding 10°C / min, hold it at 1250°C for 2 hours, and then place the high-chromium cast iron in air or quenching oil for quenching treatment to obtain quenched high-chromium cast iron.

[0081] S3. Cryogenic treatment: The quenched high-chromium cast iron of S2 is subjected to cryogenic treatment at a temperature of -196°C liquid nitrogen for 1 hour. The cryogenically treated high-chromium cast iron is then placed in air to warm up to room temperature to obtain cryogenic high-chromium cast iron.

[0082] S4. Tempering treatment: The deep cryogenic high-chromium cast iron of S3 is heated and held in a heating furnace for tempering treatment. The heating rate during tempering treatment shall not exceed 10°C / min, the tempering temperature is 450°C, and the tempering time is 2h. The tempered high-chromium cast iron is placed in air to cool to room temperature to obtain tempered low-density wear-resistant cast iron.

[0083] The preparation method of low-density wear-resistant high-chromium cast iron described in this embodiment also includes performance measurement: it is necessary to perform multi-point performance measurements on S1 high-chromium cast iron and S3 tempered low-density wear-resistant cast iron, and finally calculate the average value as the performance value of the material.

[0084] The multi-point performance measurement is performed at the riserless part of the material, the center, and at a point 1 / 4 of the thickness from the edge.

[0085] In a comparison of the properties of high-chromium cast iron S1 and tempered low-density wear-resistant cast iron S4, the density did not change significantly, but the hardness became 44.7 HRC and the impact toughness became 2.85 J.

[0086] Comparative Example 1

[0087] This comparative example describes a low-density wear-resistant high-chromium cast iron. The chemical composition of this low-density wear-resistant high-chromium cast iron, by mass percentage, is: C 3.19%, Si 0.56%, Mn 12.40%, Cr 20.23%, Cu 1.01%, Mo 0.96%, V 0.12%, Ti 0.055%, Al 5.68%, with the remainder being Fe and other unavoidable impurities. The preparation method of this low-density wear-resistant high-chromium cast iron includes quenching and tempering treatments.

[0088] A method for preparing low-density wear-resistant high-chromium cast iron, wherein the method for preparing low-density wear-resistant high-chromium cast iron is combined with... Figure 1 The preparation steps include the following:

[0089] S1. Melting and Casting: The raw materials are weighed and melted according to the composition ratio of the low-density wear-resistant high-chromium cast iron, and then cast at high temperature to obtain high-chromium cast iron; the density of the high-chromium cast iron is 7.00 g / cm³. 3 Compared to traditional high-chromium cast iron, its density is reduced by approximately 8.32%; its hardness is 53.6 HRC, and its impact toughness is 1.17 J / cm². 2 ;

[0090] S2. Quenching treatment: Cut the high-chromium cast iron of S1, heat it in a heating furnace at a rate not exceeding 10°C / min, hold it at 1200°C for 2 hours, and then quench the high-chromium cast iron in air or quenching oil to obtain quenched high-chromium cast iron.

[0091] S3. Tempering treatment: The quenched high-chromium cast iron of S2 is heated and held in a heating furnace for tempering treatment. The heating rate during tempering treatment shall not exceed 10°C / min, the tempering temperature is 450°C, and the tempering time is 2h. The tempered high-chromium cast iron is placed in air to cool to room temperature to obtain tempered low-density wear-resistant cast iron.

[0092] The preparation method of the low-density wear-resistant high-chromium cast iron described in this comparative example also includes performance measurement: multiple performance measurements need to be performed on the high-chromium cast iron of S1 and the tempered low-density wear-resistant cast iron of S3, and finally the average value is calculated as the performance value of the material.

[0093] The multi-point performance measurement is performed at the riserless part of the material, the center, and at a point 1 / 4 of the thickness from the edge.

[0094] In a comparison of the properties of high-chromium cast iron S1 and tempered low-density wear-resistant cast iron S3, the density did not change significantly, but the hardness became 51.3 HRC and the impact toughness became 2.29 J.

[0095] like Figure 2 As shown, it is a TC simulation diagram of low-density wear-resistant high-chromium cast iron, which provides a reference for the selection of heat treatment temperature range in Examples 1-3.

[0096] like Figure 3 The figure shows a comparison of the hardness of the materials after different heat treatment processes in Examples 1-3 and Comparative Example 1. It can be seen that the hardness of cast iron is significantly improved after cryogenic treatment. The cast iron has the highest hardness after quenching at 1200°C for 2 hours, cryogenic treatment for 1 hour, and tempering at 450°C for 2 hours. This heat treatment scheme can achieve better physical properties.

[0097] The above-mentioned solution proposes a low-density wear-resistant high-chromium cast iron and its preparation method, which can solve the technical problems of high density and limited hardness improvement of existing high-chromium cast iron by conventional heat treatment processes.

[0098] This invention reduces the density of cast iron from the high density of traditional high-chromium cast iron to a low density by introducing Al and Mn elements, thus achieving the low-density characteristics of wear-resistant cast iron.

[0099] This invention enables the complete transformation of ferrite into austenite by quenching high-chromium cast iron, and further transforms some of the austenite into martensite by air cooling.

[0100] This invention enables the residual austenite to be further transformed into martensite by deep cryogenic treatment of quenched high-chromium cast iron, thereby further improving the hardness of wear-resistant cast iron.

[0101] This invention releases internal stress and repairs internal microcracks by tempering cryogenic high-chromium cast iron, thereby causing the cast iron to undergo secondary hardening.

[0102] The method of this invention is stable and easy to operate. The cast iron prepared has low density, high hardness and excellent wear resistance, and is suitable for mining machinery, engineering machinery and other fields where both material weight and wear resistance are required.

[0103] In summary, compared with existing methods for preparing high-chromium cast iron, the method of this invention controls the microstructure by quenching, cryogenic treatment and tempering of high-chromium cast iron, thereby achieving synergistic optimization of hardness and density. This method is simple to operate, environmentally friendly, low in cost and high in efficiency, and is conducive to large-scale industrial production and application.

[0104] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0105] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0106] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0107] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A low-density, wear-resistant, high-chromium cast iron, characterized in that, The chemical composition of the low-density wear-resistant high-chromium cast iron, by mass percentage, is: C 3.16-3.22%, Si 0.4-0.6%, Mn 12.7-13.3%, Cr 19.0-20.0%, Cu 0.8-1.1%, Mo 0.9-1.0%, V 0.10-0.14%, Ti 0.04-0.07%, Al 5.7-6.3%, with the remainder being Fe and other unavoidable impurities. The preparation method of the low-density wear-resistant high-chromium cast iron includes quenching treatment, cryogenic treatment, and tempering treatment.

2. The low-density wear-resistant high-chromium cast iron according to claim 1, characterized in that, The microstructure of the low-density wear-resistant high-chromium cast iron consists of a martensitic matrix with a volume fraction of 45%, a retained austenite with a volume fraction of 10%, and M7C3 type carbides with a volume fraction of 45%. The M7C3 type carbides are blocky with a size of 60-80 μm, and the retained austenite has a size of 5-8 μm.

3. The low-density wear-resistant high-chromium cast iron according to claim 1, characterized in that, The density of the low-density wear-resistant high-chromium cast iron is 6.98-7.02 g / cm³. 3 Compared to traditional high-chromium cast iron, its density is reduced by 8.12-8.64%; its hardness is 53.5-55.5 HRC, and its impact toughness is 1.16-1.19 J / cm². 2 .

4. A method for preparing low-density wear-resistant high-chromium cast iron according to claim 1, characterized in that, The preparation method of the low-density wear-resistant high-chromium cast iron includes the following preparation steps: S1. Melting and casting: Weigh and melt the raw materials according to the composition ratio of the low-density wear-resistant high-chromium cast iron, and then cast the high-chromium cast iron at high temperature to obtain the high-chromium cast iron. S2. Quenching treatment: After cutting the high-chromium cast iron of S1, heat it in a heating furnace and keep it at a certain temperature. Then, place the high-chromium cast iron in air or quenching oil for quenching treatment to obtain quenched high-chromium cast iron. S3, cryogenic treatment: The quenched high-chromium cast iron of S2 is subjected to cryogenic treatment. The cryogenically treated high-chromium cast iron is placed in air to be warmed to room temperature to obtain cryogenic high-chromium cast iron. S4. Tempering treatment: The deep cryogenic high-chromium cast iron of S3 is heated and held at a temperature in a heating furnace for tempering treatment. The tempered high-chromium cast iron is then placed in air and cooled to room temperature to obtain tempered low-density wear-resistant cast iron.

5. The method for preparing low-density wear-resistant high-chromium cast iron according to claim 4, characterized in that, When quenching S2 high-chromium cast iron, the heating rate should not exceed 10°C / min, the holding temperature should be 1050-1250°C, and the holding time should be 2 hours.

6. The method for preparing low-density wear-resistant high-chromium cast iron according to claim 4, characterized in that, The cryogenic treatment in S3 is performed at a temperature of -196°C (liquid nitrogen) for 1 hour.

7. The method for preparing low-density wear-resistant high-chromium cast iron according to claim 4, characterized in that, During the tempering process in S4, the heating rate should not exceed 10°C / min, the tempering temperature should be 250-450°C, and the tempering time should be 2 hours.

8. The method for preparing low-density wear-resistant high-chromium cast iron according to claim 4, characterized in that, The preparation method of the low-density wear-resistant high-chromium cast iron also includes performance measurement: it is necessary to perform multi-point performance measurements on the high-chromium cast iron of S1 and the tempered low-density wear-resistant cast iron of S4, and finally calculate the average value as the performance value of the material.

9. The method for preparing low-density wear-resistant high-chromium cast iron according to claim 8, characterized in that, The multi-point performance measurement is performed at the riserless part of the material, the center, and at a point 1 / 4 of the thickness from the edge.

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