Wear-resistant steel ball and preparation process thereof

Abstract

The invention discloses a wear-resistant steel ball and a preparation process thereof, and relates to the technical field of steel ball manufacturing, and the wear-resistant steel ball comprises the following chemical components: Hf, B, Ta, Zr, Sb, Ca, V, Al, C, Cu, Mg, Si, Mn, Cr, P, S and the balance of Fe. The preparation process of the wear-resistant steel ball comprises the following steps: preparing raw materials: cutting an alloy steel blank with the same chemical components as the wear-resistant steel ball into a certain length, heating in an induction heating manner, and forging and pressing into a round steel billet; hot rolling into balls: after the round steel billets are heated and burnt thoroughly, rolling the round steel billets into steel balls on a ball rolling machine; quenching treatment is conducted, specifically, after the steel balls are heated to 800-900 DEG C, quenching treatment is conducted in a water cooling mode; and tempering treatment is conducted, specifically, the steel balls are heated to 190-200 DEG C in time after being quenched, heat preservation is conducted for 4 h, low-temperature tempering treatment is conducted, and then slow cooling is conducted. The grinding ball disclosed by the invention has relatively high strength and toughness and relatively good comprehensive mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of steel ball manufacturing, and in particular to a wear-resistant steel ball and a preparation process thereof. Background Art

[0002] As the main grinding medium in ball mills and semi-autogenous mills, wear-resistant steel balls play the role of crushing and grinding materials in the production process.

[0003] Grinding balls are widely used in metallurgy, mining, cement manufacturing, chemical industry, etc. According to statistics, my country consumes 3 million tons of grinding balls every year, of which the grinding balls consumed in metallurgy and mining account for 70% of the total consumption of grinding balls in the country. 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.

[0004] Increasing the hardness of the grinding balls is the most effective way to reduce wear. The normal wear of the grinding balls is a process of large balls becoming 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 grinding effect of the grinding balls be guaranteed.

[0005] The existing grinding balls generally have coarse metal crystal particles and uneven distribution, resulting in poor toughness, low hardness and high wear. At the same time, the uneven distribution of crystal particles on the surface and inside of the grinding balls makes the wear resistance vary greatly. The rate of diameter reduction during wear is uneven, which easily leads to failure of the balls. The ball breakage rate also increases, which in turn leads to an increase in ball consumption and power consumption. Summary of the invention

[0006] The object of the present invention is to provide a wear-resistant steel ball and a preparation process thereof to solve the above-mentioned defects caused by the prior art.

[0007] The invention discloses a wear-resistant steel ball. The material design is adopted to promote the synergistic effect of Hf and B which can promote the refinement of martensite crystals of the steel ball, Ta which inhibits grain growth, and Zr which refines grains by deoxidation and degassing. At the same time, high-temperature and high-compression ratio forging and high-temperature hot rolling processes are adopted to refine austenite crystals twice, and refined martensite crystals are formed by crystal inheritance and quenching treatment, and low-temperature tempering treatment is performed to obtain a wear-resistant steel ball with good comprehensive mechanical properties.

[0008] The material is designed to:

[0009] Hf: can effectively promote the refinement of martensite crystal grains and improve the strength and toughness of the material. Its price is relatively high. The present invention selects the addition range of 0.001-0.003%.

[0010] B: can improve the hardenability of the matrix; refine the martensite substructure and improve the toughness of the matrix; during the annealing process, the solid solution B preferentially guides the precipitation of secondary compounds, increases the number of secondary precipitates, and improves the uniformity of the material. The invention selects the addition range of 0.002%-0.004%.

[0011] Ta: adding trace Ta elements to the alloy can inhibit grain growth and improve the toughness of the steel ball. The present invention selects the addition range of 0.02-0.05%.

[0012] Zr: Zr can degas, purify and refine grains. It is a strong carbide-forming element. A small amount of Zr has the functions of degassing, purifying and refining grains, which is beneficial to the low-temperature performance of steel and improves stamping performance. The addition amount of Zr is 0.01-0.06%.

[0013] Supplemented with the following elements that promote grain refinement:

[0014] Sb: can precipitate MnS and refine grains. At austenite temperature, Sb in steel precipitates at MnS inclusions and along the original austenite grain boundaries, increasing the enrichment and precipitation on MnS inclusions, which can refine the steel structure and improve toughness. Taking cost factors into consideration, the Sb content of the present invention is controlled to be 0.01-0.20%.

[0015] Ca: can precipitate MnS and refine grains, form CaS with S to inhibit the formation of segregated MnS in the radial direction of the steel ball, partially desulfurize, and change the composition, quantity and form of non-metallic inclusions, improve the impact fatigue resistance of the steel ball, which is basically similar to the effect of adding rare earth to steel. The addition amount of Ca in the present invention is 0.01-0.09%.

[0016] Al: It can deoxidize and refine grains, improve impact toughness, and Al added as a strong deoxidizer can generate highly fine, ultra-micro oxides that are dispersed in the steel matrix; when improving the oxidation resistance of steel, Al is used as a final deoxidizer. When too much Al is added, the fluidity of the molten steel decreases significantly, the difficulty of casting increases greatly, and the slag inclusions such as Al2O3 in the steel also increase significantly. The addition amount of Al is selected to be 0.1-2.0%.

[0017] V: can form VC and refine grains, while improving strength and toughness. V and C form high-melting-point carbide VC, which has the advantages of high melting point and small particle size. It can also serve as the nucleation core of M7C3 type primary carbide, playing a role in refining grains. Similarly, if the V content is too low, the effect is not obvious, while if the V content is too high, the carbide formed is larger and has no refining effect. Therefore, the present invention selects a V content range of 0.5%-1.6%.

[0018] The wear-resistant steel ball has the following chemical composition percentages by mass: Hf: 0.001-0.003%, B: 0.002%-0.004%, Ta: 0.002-0.005%, Zr: 0.01-0.06%, Sb: 0.05-0.12%, Ca: 0.01-0.09%, V: 0.5-1.6%, Al: 1.0-1.5%, C: 0.7-1.3%, Cu: 0.2-0.5%, Mg: 0.2-1.0%, Si: 1.3-1.6%, Mn: 0.8-1.3%, Cr: 1.2-1.8%, P≤0.015%, S≤0.03%, and the rest is Fe.

[0019] Preferably, Sb and Ca in the chemical composition are used to synergistically remove S, and the ratio thereof is 1:2-3; and the ratio of V to Al is 1:1-1.2.

[0020] The preparation process of the wear-resistant steel ball is as follows:

[0021] Step 1: Raw material preparation: cutting the alloy steel billet with the same chemical composition as the wear-resistant steel ball into a certain length, heating it to 1100-1200°C by induction heating, and then forging it into a round billet;

[0022] Step 2: Hot rolling into balls: Heat the round steel billet to 950-1100℃, keep it warm and burn it through, then roll it into steel balls on a ball rolling machine;

[0023] Step 3: Quenching treatment: After the steel ball is heated to 800-900℃, it is quenched by water cooling;

[0024] Step 4: Tempering treatment: After quenching, the steel ball is promptly heated to 190-200℃ and kept warm for 4 hours for low-temperature tempering treatment, and then slowly cooled to room temperature.

[0025] Preferably, in step 1, the hot forging temperature is 1100-1200° C., and the compression ratio is 20-40.

[0026] Preferably, the waste heat of the round steel billet in step 1 is used for the hot rolling process in step 2, and the round steel billet is kept warm for 1 hour before the ball rolling.

[0027] Preferably, the residual heat of the steel balls in step 2 is used for the quenching process in step 3.

[0028] Preferably, the residual temperature of the steel ball after quenching in step 3 is used for the tempering process in step 4.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] In the preparation process of the present invention, material design is adopted, and the synergistic effect of Hf and B that can promote the refinement of martensite crystals of steel balls, Ta that inhibits grain growth, and Zr and other elements that deoxidize and degas to refine grains are designed, and the high compression ratio forging and hot rolling process are used to refine austenite grains for secondary refinement. The refined austenite grains are inherited into refined martensite grains through quenching, and the internal stress generated by quenching is eliminated after low-temperature tempering. The refined martensite structure has higher strength and toughness, and ensures that the grinding ball has better comprehensive mechanical properties. Its surface hardness is ≥60HRC, the hardness difference between the surface and the core is ≤2HRC, and the impact toughness is as high as 20-30J / cm2. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a flow chart of the preparation process of the wear-resistant steel ball.

[0032] Figure 2 This is the metallographic structure image of the center position in Example 1.

[0033] Figure 3 This is the metallographic structure image at the 1 / 2R position in Example 1.

[0034] Figure 4 This is the metallographic structure image of the surface position in Example 1.

[0035] Figure 5 This is the metallographic structure image of the center position in Example 2.

[0036] Figure 6 This is the metallographic structure image at the 1 / 2R position in Example 2.

[0037] Figure 7 This is the metallographic structure image of the surface position in Example 2. DETAILED DESCRIPTION

[0038] 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.

[0039] Example 1

[0040] A preparation process of wear-resistant steel balls is as follows:

[0041] Step 1: Raw material preparation: Cut the alloy steel billet with the following chemical composition mass percentages: Hf: 0.0015%, B: 0.002%, Ta: 0.0025%, Zr: 0.02%, Sb: 0.05%, Ca: 0.01%, V: 0.5%, Al: 1.05%, C: 0.9%, Cu: 0.2%, Mg: 0.2%, Si: 1.3%, Mn: 0.8%, Cr: 1.3%, P≤0.015%, S≤0.03%, and the rest Fe into a certain length, and then heat it to 1100-1200℃ by induction heating, and then forge it into a round billet with a compression ratio of 20;

[0042] Step 2: Hot rolling into balls: Heat the round steel billet to 950-1100℃, keep it warm and burn it through, then roll it into steel balls on a ball rolling machine;

[0043] Step 3: Quenching treatment: After the steel ball is heated to 800-900℃, it is quenched by water cooling;

[0044] Step 4: Tempering treatment: After quenching, the steel ball is promptly heated to 190-200℃ and kept warm for 4 hours for low-temperature tempering treatment, and then slowly cooled to room temperature;

[0045] Step 5: Use a metallographic microscope to observe the metallographic structure of different parts of the grinding ball. Figure 2-4 shown.

[0046] Example 2

[0047] A preparation process of wear-resistant steel balls is as follows:

[0048] Step 1: Raw material preparation: Cut the alloy steel billet with the following chemical composition mass percentages: Hf: 0.0025%, B: 0.003%, Ta: 0.004%, Zr: 0.05%, Sb: 0.10%, Ca: 0.08%, V: 1.3%, Al: 1.5%, C: 1.3%, Cu: 0.5%, Mg: 1.0%, Si: 1.6%, Mn: 1.0%, Cr: 1.5%, P≤0.015%, S≤0.03%, and the rest Fe into a certain length, and then heat it to 1100-1200℃ by induction heating, and forge it into a round billet with a compression ratio of 40;

[0049] Step 2: Hot rolling into balls: Heat the round steel billet to 950-1100℃, keep it warm and burn it through, then roll it into steel balls on a ball rolling machine;

[0050] Step 3: Quenching treatment: After the steel ball is heated to 800-900℃, it is quenched by water cooling;

[0051] Step 4: Tempering treatment: After quenching, the steel ball is promptly heated to 190-200℃ and kept warm for 4 hours for low-temperature tempering treatment, and then slowly cooled to room temperature;

[0052] Step 5: Use a metallographic microscope to observe the metallographic structure of different parts of the grinding ball. Figure 5-7 shown.

[0053] illustrate: Figure 2-4 It is low carbon and low content refined grain (Hf: 0.0015%, B: 0.002%, Ta: 0.0025%, Zr: 0.02%), Figure 5-7 The high carbon and high content refined grains (Hf: 0.0025%, B: 0.003, Ta: 0.004%, Zr: 0.05%) have similar effects on martensite crystal refinement.

[0054]

[0055] Therefore, the embodiments disclosed above are only illustrative in all aspects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A wear-resistant steel ball, characterized in that: The chemical composition by mass percentage is as follows: Hf: 0.001-0.003%, B: 0.002%-0.004%, Ta: 0.002-0.005%, Zr: 0.01-0.06%, Sb: 0.05-0.12%, Ca: 0.01-0.09%, V: 0.5-1.6%, Al: 1.0-1.5%, C: 0.7-1.3%, Cu: 0.2-0.5%, Mg: 0.2-1.0%, Si: 1.3-1.6%, Mn: 0.8-1.3%, Cr: 1.2-1.8%, P≤0.015%, S≤0.03%, and the rest is Fe.

2. A wear-resistant steel ball according to claim 1, characterized in that: The Sb and Ca in the chemical composition are used to synergistically remove S, and the ratio thereof is 1:2-3; the ratio of V to Al is 1:1-1.

2.

3. A wear-resistant steel ball according to claim 1, characterized in that: The preparation process includes the following: Step 1: Raw material preparation: cutting the alloy steel billet with the same chemical composition as the wear-resistant steel ball into a certain length, heating it to 1100-1200°C by induction heating, and then forging it into a round billet; Step 2: Hot rolling into balls: Heat the round steel billet to 950-1100℃, keep it warm and burn it through, then roll it into steel balls on a ball rolling machine; Step 3: Quenching treatment: After the steel ball is heated to 800-900℃, it is quenched by water cooling; Step 4: Tempering treatment: After quenching, the steel ball is promptly heated to 190-200℃ and kept warm for 4 hours for low-temperature tempering treatment, and then slowly cooled to room temperature.

4. A wear-resistant steel ball according to claim 3, characterized in that: In step 1, the hot forging temperature is 1100-1200° C., and the compression ratio is 20-40.

5. The wear-resistant steel ball according to claim 3, characterized in that: The residual heat of the round steel billet in step 1 is used for the hot rolling process in step 2, and the round steel billet is kept warm for 1 hour before the ball rolling.

6. The wear-resistant steel ball according to claim 3, characterized in that: The residual heat of the steel ball in step 2 is used for the quenching process in step 3.

7. The wear-resistant steel ball according to claim 3, characterized in that: The residual temperature of the steel ball after quenching in step 3 is used for the tempering process in step 4.

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