Process for uniformly dispersing carbon in production process of wear-resistant steel balls

Abstract

The invention discloses a process for uniformly dispersing carbon in a wear-resistant steel ball production process, which relates to the technical field of wear-resistant steel balls and comprises the following steps: cutting an alloy steel blank containing components into a certain length, heating the alloy steel blank to 1100-1200 DEG C in an induction heating manner, keeping the temperature for 1 hour, performing high-temperature diffusion, and forging and pressing the alloy steel blank into a round steel blank at high temperature and high compression ratio; carrying out hot rolling balling, quenching treatment and tempering treatment; through Co, Se and other elements capable of refining carbides in a specific proportion and Hf, matrix structure refinement is promoted, carbide uniform distribution is effectively improved, W, B, Ti, Mo, V and other dispersive combinations capable of promoting three-dimensional diffusion of carbon and carbides in a steel body in a specific proportion are combined, meanwhile, through high-temperature heat preservation, high-temperature forging and pressing and high-compression-ratio forging and pressing, carbon uniform dispersion is promoted, and the strength of the steel body is improved. And hot rolling balling and heat preservation are carried out, carbon is further kept to be evenly dispersed, quenching is carried out to enable carbon to be evenly dispersed in martensite, low-temperature tempering treatment is carried out, and the wear-resistant steel ball with good comprehensive mechanical properties can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of wear-resistant steel balls, and in particular to a process for uniformly dispersing carbon in the production process of wear-resistant steel balls. Background Art

[0002] Wear-resistant steel balls are the main grinding media in ball mills and semi-autogenous mills, and they play a role in crushing and grinding materials in the production process. Grinding balls are widely used in metallurgy, mining, cement manufacturing, chemical industry and other fields. The huge loss of grinding balls has attracted people's attention. The quality of grinding balls directly affects the production cost and production efficiency. Improving the efficiency of grinding balls has become one of the issues that enterprises and related workers are concerned about. Increasing the hardness of grinding balls is the most effective way to reduce wear. The normal wear of grinding balls is the wear process of large balls turning into small balls. Only by maintaining the round shape during the entire wear process and ensuring that the inside and outside of the grinding balls have sufficient hardness and wear resistance can the normal effect of grinding balls be guaranteed.

[0003] The existing grinding balls generally have carbon segregation and uneven carbon distribution, which leads to low hardness and high wear. At the same time, the carbon content and distribution density between the surface and the inside of the grinding balls are quite different, which makes the diameter reduction rate during the wear process uneven, easily forming failed balls, and the ball breakage rate increases, resulting in an increase in ball consumption. Therefore, a process for uniform carbon dispersion in the production process of wear-resistant steel balls is needed to solve the above problems. Summary of the invention

[0004] The object of the present invention is to provide a process for uniformly dispersing carbon in the production process of wear-resistant steel balls and wear-resistant steel balls, so as to solve the problems existing in the prior art mentioned in the above background technology.

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

[0006] A wear-resistant steel ball comprises the following components in percentage by mass:

[0007] Co: 0.001-0.005%, Se: 0.002-0.006%, Hf: 0.002-0.005%, W: 0.2-0.7%, B: 0.4-0.8%, C: 0.7-1.3%, Ti: 0.02-0.04%, Mo: 0.01-0.20%, Cu: 0.8-1.0%, V: 0.5-1.6%, Mn: 0.92-1.2%, Cr: 0.5-1.5%, Al: 0.3-0.8%, Si: 1.40-1.70%, Mg: 0.002-0.003%, Nb: 0.1-0.3%, P≤0.015%, S≤0.03%, and the rest is Fe.

[0008] The present invention uses elements such as Co and Se that can refine carbides and Hf to promote matrix microstructure refinement, effectively improving the uniform distribution of carbides, and a combination of W, B, Ti, Mo, V, etc. that promote the three-dimensional diffusion of carbon and carbides in the steel body. At the same time, high-temperature heat preservation, high-temperature forging, and high-compression ratio forging are used to promote uniform dispersion of carbon, hot rolling and ball insulation are used to further ensure uniform dispersion of carbon, quenching is performed to make carbon uniformly dispersed in martensite, and low-temperature tempering is performed to obtain wear-resistant steel balls with good comprehensive mechanical properties.

[0009] Co can inhibit the precipitation and aggregation of carbides of other elements during tempering, improve the quenching performance of steel, and improve the hardness and strength of alloy steel. However, too high a content will reduce the hardenability of steel and cause a decrease in plasticity and impact toughness. In order to obtain the above effects, the content of Co in the steel ball of the present invention is 0.001-0.005%.

[0010] Se reacts chemically with the iron element in the alloy steel to form a strengthened alloy phase, making the lattice structure of the alloy steel more compact, refining carbides, and significantly improving the strength and toughness of the steel. The content of Se in the steel ball of the present invention is 0.002-0.006%.

[0011] Hf can refine the matrix structure, improve the distribution of carbides, increase impact toughness and wear resistance. The Hf content is controlled to be 0.002-0.005%.

[0012] W can form high-hardness tungsten carbide WC in the matrix, which can refine carbides. If the W content is too low, W will mainly exist in the form of solid solution, which has a weak effect on refining primary carbides; but if the tungsten content is too high, a large amount of tungsten carbides will be formed, which is not good for the wear resistance of the steel ball. Therefore, the present invention selects a W content range of 0.2-0.7%.

[0013] B can replace some C atoms in carbides to form B-containing alloy carbides, making the carbides fine and distributed in isolated clusters, thereby improving impact toughness. However, too high a boron content will make the carbides coarse and reduce toughness. Therefore, the B content in the present invention is limited to between 0.4-0.8%.

[0014] And in conjunction with the following other elements:

[0015] Ti can form carbides TiC formed by titanium in the matrix. The carbides have the advantages of high hardness and small particle size, can be evenly distributed in the steel structure, and are solid dissolved in the matrix. They can delay the transformation of austenite to pearlite, which is beneficial to improving the hardenability of the material and the wear performance of the steel ball. If the titanium content is too high, the carbides formed are easy to agglomerate to form coarse carbides, which not only reduces the strength and toughness, but also makes the steel ball easy to crack. Therefore, the Ti content in the present invention is limited to between 0.02-0.04%.

[0016] Mo can be dissolved in carbides, refine grains, and react with carbon to generate Mo2C compounds. Molybdenum carbide, i.e., Mo2C, is a hexagonal lattice structure with high microhardness, so it has a significant effect on improving the wear resistance of the wear-resistant steel ball, improving hardenability and heat resistance, maintaining sufficient strength and creep resistance at high temperatures, and inhibiting the brittleness of alloy steel caused by tempering, so the Mo content is controlled to 0.01-0.20%. However, the increase of more Mo greatly increases the cost, so by controlling the addition of a certain amount of Cu and controlling the weight ratio of Mo to Cu to 1:3-4, it can be compounded with Mo, while ensuring wear resistance enhancement, reducing the amount of Mo used.

[0017] The addition of Cu can also improve the distribution of carbides, increase the hardness and impact toughness of alloy steel, and make the hardness of the center and surface of the steel ball basically consistent, so 0.8-1.0% Cu is added in the determination of the composition.

[0018] V forms carbide VC with C in the matrix, which is an element that is beneficial to inhibiting the growth of austenite grains and improving the quenching performance to ensure strength and toughness. The carbide has the advantages of high melting point and small particle size. It can also serve as the nucleation core of M7C3 type primary carbides to play a role in refining grains. Similarly, if the V content is too low, the effect is not obvious, while if the vanadium content is too high, the carbide formed is large and has no refining effect. Therefore, the present invention selects a vanadium content range of 0.5-1.6%.

[0019] Mn can increase the solubility of VC in austenite, improve the hardenability in steel, ensure that the center of the steel ball is also easy to quench to obtain martensite structure, reduce the hardness difference between the inside and outside of the steel ball after quenching, and Mn also has a certain solid solution strengthening effect, but too high Mn content will cause serious carbon segregation. Therefore, after comprehensive consideration, the Mn content is controlled to 0.92-1.2%.

[0020] Part of the Cr in the steel replaces iron to form alloy cementite, improving its stability, and part of it dissolves in ferrite, producing solid solution strengthening, improving the strength and hardness of ferrite; when the content is low, it can form chromium alloy cementite Cr3C, and as the chromium content increases, the carbides in the steel gradually change to Cr23C6 and Cr7C3. Since the diffusion rate of chromium in austenite is relatively low, and it hinders the diffusion of carbon, it can improve the stability of austenite, shift the C curve to the right, reduce the critical cooling rate, and improve hardenability. Chromium also reduces the phase transition temperature, so that carbides can precipitate at a lower temperature, making the structure and carbides refined. Cr can effectively prolong the incubation period of austenite transformation, improve the hardenability of steel, and reduce the temperature at which martensite begins to transform. Taking all factors into consideration, the chromium addition amount is selected to be 0.5-1.5%.

[0021] As a deoxidizing element, Al can inhibit the oxidation of Cr and other elements, effectively promote the solid solution of Cr in the matrix, obtain a sufficient amount of carbides, and help refine the carbides, thereby obtaining the required hardness and toughness.

[0022] Si can strengthen by solid solution, hinder the precipitation of cementite, improve the dispersion of carbides, ensure the carbon content in austenite, and increase the strength of austenite. If the Si content is too high, especially when it coexists with Mn and Cr elements, it will easily cause grain coarsening and increase the temper brittleness of the steel, reduce the hardness, and also reduce the toughness. Taking all factors into consideration, the Si content is controlled to be 1.40-1.70%.

[0023] Mg can reduce the number of inclusions in steel, reduce their size, make their distribution uniform, and improve their morphology. Trace magnesium can improve the carbide size and distribution of alloy steel, and promote the fine and uniform carbide particles. When the Mg content is 0.002%-0.003%, its tensile strength and yield strength increase by more than 5%, and the plasticity remains basically unchanged.

[0024] Nb forms fine carbides in the matrix, which can act as heterogeneous nuclei during solidification, increase the nucleation rate, and refine the crystal structure. At the same time, at the austenitizing temperature, the presence of NbC particles can prevent the growth of austenite grains, thereby increasing the matrix hardness and wear resistance. In order to effectively exert this effect, the niobium content in the present invention is selected to be in the range of 0.1-0.3%.

[0025] In order to use the above raw materials to prepare wear-resistant steel balls, the present invention also discloses a process for uniformly dispersing carbon in the production process of wear-resistant steel balls, comprising the following steps:

[0026] S1: Raw material preparation: the alloy steel billet containing various components is cut into a certain length, heated to 1100-1200°C by induction heating, kept warm for 1 hour for high temperature diffusion, and then forged into a round steel billet at high temperature and high compression ratio;

[0027] S2: hot rolling into balls: heating the round steel billet to 950-1100°C, keeping the temperature for 1 hour after burning through, and rolling it into steel balls on a ball rolling machine;

[0028] S3: Quenching treatment: the steel ball is heated to 800-900°C and quenched by water cooling;

[0029] S4: Tempering treatment: After quenching the steel ball, heat it to 190-200℃ in time, keep it warm for 4h for low-temperature tempering treatment, and then cool it to room temperature.

[0030] Preferably, the forging temperature in S1 is 1100-1200° C., and the ratio of the initial and final cross-sectional areas of the forging is 40.

[0031] Preferably, the temperature of hot rolling into balls in S2 utilizes the residual temperature of the round steel billet in S1, and the round steel billet in S1 is kept warm for 1 hour before hot rolling into balls.

[0032] Preferably, the residual temperature of the steel balls in S2 is used for quenching the steel balls in S3.

[0033] Preferably, the residual temperature of the steel balls in S3 is used for tempering the steel balls in S4.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention uses a specific proportion of Co, Se and other elements that can refine carbides and Hf to promote matrix structure refinement, effectively improving the uniform distribution of carbides, and a specific proportion of W, B, Ti, Mo, V and other elements that promote the three-dimensional diffusion of carbon and carbides in the steel body. At the same time, high-temperature heat preservation, high-temperature forging, and high-compression ratio forging are used to promote uniform dispersion of carbon, hot rolling and ball insulation are used to further ensure uniform dispersion of carbon, quenching is performed to make carbon uniformly dispersed in martensite, and low-temperature tempering is performed to obtain wear-resistant steel balls with good comprehensive mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the metallographic structure diagram of the wear-resistant steel ball prepared in Example 1 of the present invention.

[0037] Figure 2 This is the metallographic structure diagram of the wear-resistant steel ball prepared in Example 2 of the present invention.

[0038] In the figure: (a) is the center position of the wear-resistant steel ball, (b) is the 1 / 2R position of the wear-resistant steel ball, and (c) is the surface of the wear-resistant steel ball DETAILED DESCRIPTION

[0039] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0040] See also Figure 1-2 , the present invention provides the following technical solutions:

[0041] Example 1

[0042] A carbon uniform dispersion process in the production process of wear-resistant steel balls comprises the following steps:

[0043] S1: Raw material preparation: alloy steel billets with chemical composition mass percentages of Co: 0.002%, Se: 0.003%, Hf: 0.003%, W: 0.3%, B: 0.4%, C: 0.8%, Ti: 0.02%, Mo: 0.07%, Cu: 0.8%, V: 0.5%, Mn: 0.95%, Cr: 0.6%, Al: 0.3%, Si: 1.40%, Mg: 0.002%, Nb: 0.1%, P≤0.015%, S≤0.03%, and the rest being Fe are cut into a certain length, heated to 1150°C by induction heating, kept warm for 1h for high temperature diffusion, and then forged into round steel billets at high temperature and high compression ratio;

[0044] S2: hot rolling into balls: heating the round steel billet to 1000°C, keeping the temperature for 1 hour after burning through, and rolling it into steel balls on a ball rolling machine;

[0045] S3: Quenching treatment: the steel ball is heated to 850°C and quenched by water cooling;

[0046] S4: Tempering treatment: After quenching the steel ball, heat it to 195℃ in time, keep it warm for 4h for low-temperature tempering treatment, and then cool it to room temperature.

[0047] The metallographic structure of different parts of the grinding ball was observed using a metallographic microscope. Figure 1 shown.

[0048] Example 2

[0049] S1: Raw material preparation: alloy steel billets with chemical composition mass percentages of Co: 0.004%, Se: 0.005%, Hf: 0.005%, W: 0.5%, B: 0.7%, C: 1.2%, Ti: 0.04%, Mo: 0.20%, Cu: 1.0%, V: 1.5%, Mn: 1.0%, Cr: 1.3%, Al: 0.8%, Si: 1.70%, Mg: 0.003%, Nb: 0.3%, P≤0.015%, S≤0.03%, and the rest being Fe are cut into a certain length, heated to 1150°C by induction heating, kept warm for 1h for high temperature diffusion, and then forged into round steel billets at high temperature and high compression ratio;

[0050] S2: hot rolling into balls: heating the round steel billet to 1000°C, keeping the temperature for 1 hour after burning through, and rolling it into steel balls on a ball rolling machine;

[0051] S3: Quenching treatment: the steel ball is heated to 850°C and quenched by water cooling;

[0052] S4: Tempering treatment: After quenching the steel ball, heat it to 195℃ in time, keep it warm for 4h for low-temperature tempering treatment, and then cool it to room temperature.

[0053] The metallographic structure of different parts of the grinding ball was observed using a metallographic microscope. Figure 2 shown.

[0054] Figure 1 It is a low-carbon, low-content carbon dispersion component (Co: 0.002%, Se: 0.003%, Hf: 0.003%, W: 0.3%, B: 0.4%) and Figure 2 High carbon and high content carbon dispersed components (Co: 0.004%, Se: 0.005%, Hf: 0.005%, W: 0.5%, B: 0.7%), the surface hardness, surface and core hardness difference and impact energy of the steel balls prepared in Examples 1 and 2 were tested, and the test results are as follows:

[0055]

[0056] By comparing the test results of Examples 1 and 2, it can be concluded that both have similar effects on carbon dispersion, and both can obtain wear-resistant steel balls with good comprehensive mechanical properties.

[0057] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A wear-resistant steel ball, It is characterized in that The components include the following mass percentages: Co: 0.001-0.005%, Se: 0.002-0.006%, Hf: 0.002-0.005%, W: 0.2-0.7%, B: 0.4-0.8%, C: 0.7-1.3%, Ti: 0.02-0.04%, Mo: 0.01-0.20%, Cu: 0.8-1.0%, V: 0.5-1.6%, Mn: 0.92-1.2%, Cr: 0.5-1.5%, Al: 0.3-0.8%, Si: 1.40-1.70%, Mg: 0.002-0.003%, Nb: 0.1-0.3%, P≤0.015%, S≤0.03%, and the rest is Fe.

2. A wear-resistant steel ball according to claim 1, Features: The weight ratio of Mo to Cu is 1:3-4.

3. A process for uniformly dispersing carbon in the production process of wear-resistant steel balls as claimed in claim 1 or 2, It is characterized in that The steps include: S1: Raw material preparation: the alloy steel billet containing various components is cut into a certain length, heated to 1100-1200°C by induction heating, kept warm for 1 hour for high temperature diffusion, and then forged into a round steel billet at high temperature and high compression ratio; S2: hot rolling into balls: heating the round steel billet to 950-1100°C, keeping the temperature for 1 hour after burning through, and rolling it into steel balls on a ball rolling machine; S3: Quenching treatment: the steel ball is heated to 800-900°C and quenched by water cooling; S4: Tempering treatment: After quenching, the steel ball is heated to 190-200℃ in time, kept warm for 4 hours for low-temperature tempering treatment, and then cooled to room temperature.

4. The carbon uniform dispersion process in the production process of wear-resistant steel balls according to claim 3, Features: The forging temperature in S1 is 1100-1200°C, and the ratio of the initial and final cross-sectional areas of the forging is 40.

5. The carbon uniform dispersion process in the production process of wear-resistant steel balls according to claim 3, Features: The temperature of hot rolling into balls in S2 utilizes the residual temperature of the round steel billet in S1. The round steel billet in S1 is kept warm for 1 hour before hot rolling into balls.

6. The carbon uniform dispersion process in the production process of wear-resistant steel balls according to claim 3, Features: The residual temperature of the steel balls in S2 is used for quenching the steel balls in S3.

7. The carbon uniform dispersion process in the production process of wear-resistant steel balls according to claim 3, Features: The residual temperature of the steel balls in S3 is used for tempering of the steel balls in S4.

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