A wear-resistant forged ball high-efficiency heat treatment device and method

Abstract

The invention relates to a wear-resistant forged ball high-efficiency heat treatment device and method. The forged ball obtained by forging is first heated to 1050°C, kept warm for 30-45 minutes, then air-cooled to 800-810°C, kept warm for 2 hours; then cooled to 760-780°C, and ultrasonic megasonic centrifugal water quenching is performed, the quenching agent used in the ultrasonic megasonic centrifugal water quenching is water, and ultrasonic waves and megasonic waves simultaneously vibrate the forged ball and water in a centrifugal environment; then, low-temperature tempering is performed at 210°C for 3 hours to obtain the wear-resistant forged ball. The invention optimizes and designs the 60Mn formula to further improve the mechanical properties of the alloy, making it more suitable for the production of wear-resistant forged balls. By optimizing and improving the heat treatment method, the carbide dispersion of the matrix structure is controlled to improve the toughness, hardness and wear resistance, especially the thickness of the hardened layer. In the heat treatment process, the hardenability of the water quenching can be significantly improved by combining ultrasonic waves, megasonic waves and centrifugal force, thereby significantly improving the thickness of the hardened layer.

Description

Technical Field

[0001] The invention relates to a highly efficient heat treatment device and method for a wear-resistant forged ball, belonging to the technical field of metal material processing. Background Art

[0002] Wear-resistant forged balls / wear-resistant steel balls are a kind of grinding media in ball mills, used to crush materials in ball mills. During the working process, wear-resistant forged balls are repeatedly lifted to a certain height and then dropped, and gradually worn by the impact, friction and extrusion of the materials to be crushed and the liner of the ball mill. In particular, the wear-resistant forged balls used in large mills are lifted to an increased height, and the impact, friction and extrusion they are subjected to are more severe, so the wear-resistant forged balls are required to have better hardness, wear resistance, impact resistance and other properties.

[0003] 60Mn carbon steel is the raw material for producing large diameter wear-resistant forged balls (such as 10 cm in diameter). However, in practical applications, large diameter wear-resistant forged balls often have problems such as quench cracking, insufficient hardenability, and small depth of hardened layer.

[0004] For example, the "Preparation method of tempered martensitic wear-resistant steel ball with multi-phase precipitated TiC particles" disclosed in the authorization announcement number CN111485180A, the wear-resistant steel ball is made of the following alloy components in weight percentage: C: 0.65-0.9wt.%, Si: 1.5-3.0wt.%, Mn: 0.5-2.0wt.%, Cr: 0.5-1.5wt.%, Ti: 1-2%, the balance is Fe and inevitable impurities; through forging residual heat quenching (no need to reheat) + low temperature tempering process, a high-hardness tempered martensitic structure is obtained, and second-phase particles are precipitated in the matrix. The strength and wear resistance of the material are ensured by the dispersed second-phase particles of different scales. The nano-scale precipitated particles improve the strength of the matrix, while the micron-scale precipitated particles improve the wear resistance of the material. In this alloy system, adding different contents of Ti elements can significantly improve the comprehensive performance of the material.

[0005] For another example, the "A wear-resistant steel forging for ball mill and its preparation method" disclosed in publication number CN109023088B includes the following components: Cr, Mn, C, Ti, B, Al, Si, Zr, Mo, Ni, V, Nb, Sc, Nd, Y, and the rest is Fe and inevitable impurities. The wear-resistant steel forging for ball mill and its preparation method proposed in the present invention have good wear resistance and mechanical properties, long service life and good grinding effect by optimizing the formula and preparation process.

[0006] However, the wear-resistant forged ball made by the above method can be water quenched at 800℃ if its diameter is less than 10cm; if the water quenching temperature is lower than 800℃, it will cause defects such as decreased hardness and decreased thickness of the hardened layer. Once the diameter of the wear-resistant forged ball exceeds 10cm, the forged ball often has defects such as quenching cracks, insufficient hardenability, and decreased thickness of the hardened layer.

[0007] Based on this, the present invention is proposed. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a wear-resistant forged ball efficient heat treatment device and method, and the specific technical scheme is as follows:

[0009] A high-efficiency heat treatment method for a wear-resistant forged ball comprises the following steps:

[0010] The forged ball is first heated to 1050°C, kept at this temperature for 30-45 minutes, then air-cooled to 800-810°C, kept at this temperature for 2 hours; then cooled to 760-780°C, and subjected to ultrasonic megasonic centrifugal water quenching, wherein the quenching agent used in the ultrasonic megasonic centrifugal water quenching is water, and ultrasonic waves and megasonic waves simultaneously vibrate the forged ball and water in the centrifugal environment;

[0011] After that, the wear-resistant forged ball can be obtained by low temperature tempering at 210℃ for 3h;

[0012] The method for making the forged ball comprises the following steps:

[0013] Step 1, smelting the alloy raw material in a smelting furnace, and after slagging and standing, using a continuous casting machine to cast into a round ingot; then placing the round ingot in a five-stage heating furnace for homogenization, and rolling to obtain a rod-shaped rolled piece;

[0014] Step 2: saw the rod-shaped rolled parts into round bars, and use an air hammer to perform rough forging, fine forging, and trimming the round bars into forged balls.

[0015] As a further optimization solution, in step 1, the forged ball is made of the following components in weight percentage:

[0016] C: 0.6%~0.7wt%; Mn: 0.85%~0.95wt%; Si: 0.5%~0.6wt%; P: ≤0.012%;

[0017] Cr: 0.3-0.35wt%; Ni: 0.1%-0.15%; Al: ≤0.02%; Ti: 1%-1.5%; the rest is Fe and unavoidable impurities;

[0018] In step 1, the alloy raw materials are weighed according to the above ratio.

[0019] As a further optimization scheme, in step 1, the composition of the molten steel in the ladle in the smelting furnace is tested. After passing the test, the molten steel in the ladle is deslagging and allowed to stand until the temperature of the molten steel drops to 1535-1550°C, and then the molten steel is poured into the continuous casting machine for casting.

[0020] As a further optimization scheme, in step 1, the temperature of the preheating section in the five-stage heating furnace is 550-560°C, the temperature of the heating section is 700-810°C, the temperature of the heating section is 950-1000°C, the temperature of the even heating section is 1130-1160°C, and the temperature of the even heating section is 1160°C; the even heating section is kept warm for 2-2.5 hours.

[0021] As a further optimization scheme, in step 1, during rolling, the starting rolling temperature is 1050-1150°C, and the finishing rolling temperature is 900-950°C.

[0022] As a further optimization scheme, in step 2, the starting forging temperature of the round bar is 1130-1165°C, after forging, the surface temperature of the forging ball is 990-1020°C, and the forging time is 25-30s.

[0023] As a further optimization scheme, the centrifugal speed corresponding to the centrifugal environment in the ultrasonic megasonic centrifugal water quenching is 500-3300 r / min, the ultrasonic frequency of the ultrasonic wave is 20-100 kHz, and the megasonic frequency of the megasonic wave is greater than or equal to 800 kHz.

[0024] As a further optimization scheme, a wear-resistant forged ball high-efficiency heat treatment device is used to perform ultrasonic megasonic centrifugal water quenching on the forged ball, the wear-resistant forged ball high-efficiency heat treatment device comprises a water tank, a cylindrical metal screen installed inside the water tank, a plurality of ultrasonic generating components, and a plurality of megasonic generating components, a hollow rotating shaft is installed below the bottom of the water tank, the interior of the water tank is divided into a heat treatment chamber and a sonic chamber located between the side wall of the water tank and the metal screen by the metal screen, the megasonic generating component is provided with a rotating megasonic probe, the ultrasonic generating component is provided with a rotating ultrasonic probe, the lower sections of the rotating megasonic probe and the rotating ultrasonic probe are both arranged in the sonic chamber, and the upper ends of the rotating megasonic probe and the rotating ultrasonic probe are both arranged outside the sonic chamber;

[0025] A boss is arranged at the center of the heat treatment chamber, the outer periphery of the boss is a rotating curved surface structure, and the cross section of the boss is an arc-shaped structure concave inwardly; a core shaft is integrally connected to the top of the boss, and the core shaft is coaxially arranged with the boss, and the boss includes a plurality of first cylindrical segments and second cylindrical segments, and a first rotating curved surface segment is arranged between two adjacent first cylindrical segments, and the height of the first rotating curved surface segment is arranged in geometric increments from bottom to top, and the side wall of the first rotating curved surface segment is a rotating curved surface structure, and the first rotating curved surface segment is a rotating curved surface structure. The cross-section of the surface segment is an inwardly concave arc structure, and the surface of the first rotating curved surface segment is a mirror surface; the diameter of the second cylindrical segment is larger than the diameter of the first cylindrical segment, a second rotating curved surface segment is arranged between the second cylindrical segment and the topmost first cylindrical segment, the side wall of the second rotating curved surface segment is a rotating curved surface structure, the cross-section of the second rotating curved surface segment is an inwardly concave arc structure, and the surface of the second rotating curved surface segment is a mirror surface; a plurality of discharge valves connected to the heat treatment chamber are also arranged below the bottom of the water tank.

[0026] As a further optimization scheme, at least three rotating ultrasonic probes are provided, and a megasonic probe unit is provided between two adjacent rotating ultrasonic probes. The megasonic probe unit is composed of at least one rotating megasonic probe. The number of rotating megasonic probes in the megasonic probe unit is reduced by one according to the direction of the water tank. The direction of the rotating megasonic probes is opposite to the direction of the water tank, and the direction of the rotating ultrasonic probes is the same as the direction of the water tank.

[0027] As a further optimization solution, the speed of the water tank is V s , unit is r / min;

[0028] When the rotary ultrasonic probe performs ultrasonic operation, the ultrasonic frequency is f US , 20kHz≤f US ≤100kHz;

[0029] When the rotary megasonic wave probe performs megasonic operation, the megasonic frequency is f MS , f MS ≥800kHz;

[0030] When 500r / min≤V s ≤1200r / min, V s =λf US 2 +θf MS , 0.01<λ<1, 0.1≤θ≤1, λ and θ are correction coefficients;

[0031] When 1200r / min<V s≤3300r / min, 79kHz≤f US ≤100kHz, f US Positively correlated with the diameter of the wear-resistant forged ball, V s =βf MS , 1≤β≤2, β is the correction coefficient.

[0032] Beneficial effects of the present invention:

[0033] 1. The present invention optimizes the design of 60Mn formula to further improve the mechanical properties of the alloy, making it more suitable for the production of wear-resistant forged balls.

[0034] 2. By optimizing and improving the heat treatment method, the carbide dispersion in the matrix structure is controlled to improve the toughness, hardness and wear resistance, especially the thickness of the hardened layer.

[0035] 3. During the heat treatment process, the hardenability of water quenching can be significantly improved through the combination of ultrasonic waves, megasonic waves and centrifugal force, thereby significantly increasing the thickness of the hardened layer (that is, the thickness-to-diameter ratio).

[0036] 4. Avoid quenching cracks by lowering the quenching temperature; use a dedicated wear-resistant forged ball high-efficiency heat treatment device for ultrasonic megasonic centrifugal water quenching to improve defects such as insufficient hardenability and reduced hardening layer thickness caused by the decrease in quenching temperature.

[0037] 5. The wear-resistant forged ball produced by the present invention adopts ultrasonic megasonic centrifugal water quenching, which can greatly reduce the uneven surface hardness and possible cracks, surface peeling and other phenomena caused by the heat treatment of the forged ball, and has a good quenching effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic structural diagram of the wear-resistant forged ball high-efficiency heat treatment device of the present invention;

[0039] Figure 2 It is a schematic diagram of the distribution of the rotary megasonic probe and the rotary ultrasonic probe of the present invention;

[0040] Figure 3 It is a structural schematic diagram of the core shaft described in the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0042] Example 1

[0043] A high-efficiency heat treatment method for a wear-resistant forged ball comprises the following steps:

[0044] The forged ball is first heated to 1050°C and kept at this temperature for 30 minutes, then air-cooled to 800°C and kept at this temperature for 2 hours; then cooled to 760°C and subjected to ultrasonic megasonic centrifugal water quenching, wherein the quenching agent used in the ultrasonic megasonic centrifugal water quenching is water, and ultrasonic waves and megasonic waves simultaneously vibrate the forged ball and water in a centrifugal environment;

[0045] After that, the wear-resistant forged ball can be obtained by low temperature tempering at 210℃ for 3h.

[0046] Wherein, the method for making the forged ball comprises the following steps:

[0047] Step 1: The alloy raw materials are weighed according to the above ratio, and the forged ball is made of the following components in weight percentage:

[0048] C: 0.6%~0.7wt%; Mn: 0.85%~0.95wt%; Si: 0.5%~0.6wt%; P: ≤0.012%;

[0049] Cr: 0.3~0.35wt%; Ni: 0.1%~0.15%; Al: ≤0.02%; Ti: 1%~1.5%; the rest is Fe and unavoidable impurities.

[0050] The alloy raw materials are smelted in a smelting furnace, and the composition of the molten steel in the ladle in the smelting furnace is tested. After the test is qualified, the molten steel in the ladle is slag-stripped and left to stand until the temperature of the molten steel drops to 1535-1545°C, and then the molten steel is poured into a continuous casting machine to cast into a round billet; then the round billet is placed in a five-stage heating furnace for homogenization and rolled to obtain a rod-shaped rolled piece; the preheating section temperature in the five-stage heating furnace is 550-565°C, the heating section temperature is 700-750°C, the heating section temperature is 950-980°C, the soaking section temperature is 1130-1150°C, and the soaking section temperature is 1160°C; keep warm in the soaking section for 2 hours. During rolling, the starting rolling temperature is 1050-1150°C and the final rolling temperature is 900-950°C.

[0051] Step 2: saw the rod-shaped rolled piece into round bars, and use an air hammer to perform rough forging, fine forging, and trimming the round bars into forged balls. The starting forging temperature of the round bars is 1130-1165°C, and after forging, the surface temperature of the forged balls is 990-1020°C, and the forging time is 25-30s.

[0052] In addition, the centrifugal speed corresponding to the centrifugal environment in the ultrasonic megasonic centrifugal water quenching is 500-3300 r / min, the ultrasonic frequency of the ultrasonic wave is 20-100 kHz, and the megasonic frequency of the megasonic wave is greater than or equal to 800 kHz.

[0053] The yield strength of the rod-shaped rolled product is 672 MPa and the tensile strength is 1071 MPa. The diameter of the wear-resistant forged ball is 20 cm and no quenching cracks occur during quenching.

[0054] Example 2

[0055] A high-efficiency heat treatment method for a wear-resistant forged ball comprises the following steps:

[0056] The forged ball is first heated to 1050°C, kept at this temperature for 30-45 minutes, then air-cooled to 805°C, kept at this temperature for 2 hours; then cooled to 770°C, and subjected to ultrasonic megasonic centrifugal water quenching, wherein the quenching agent used in the ultrasonic megasonic centrifugal water quenching is water, and ultrasonic waves and megasonic waves simultaneously vibrate the forged ball and water in the centrifugal environment;

[0057] After that, the wear-resistant forged ball can be obtained by low temperature tempering at 210℃ for 3h.

[0058] Wherein, the method for making the forged ball comprises the following steps:

[0059] Step 1: The alloy raw materials are weighed according to the above ratio, and the forged ball is made of the following components in weight percentage:

[0060] C: 0.6%~0.7wt%; Mn: 0.85%~0.95wt%; Si: 0.5%~0.6wt%; P: ≤0.012%;

[0061] Cr: 0.3~0.35wt%; Ni: 0.1%~0.15%; Al: ≤0.02%; Ti: 1%~1.5%; the rest is Fe and unavoidable impurities.

[0062] The alloy raw materials are smelted in a smelting furnace, and the composition of the molten steel in the ladle in the smelting furnace is tested. After the test is qualified, the molten steel in the ladle is slag-stripped and left to stand until the temperature of the molten steel drops to 1535-1545°C, and then the molten steel is poured into a continuous casting machine to cast into a round billet; then the round billet is placed in a five-stage heating furnace for homogenization and rolled to obtain a rod-shaped rolled piece; the preheating section temperature in the five-stage heating furnace is 550-555°C, the heating section temperature is 750-790°C, the heating section temperature is 960-980°C, the soaking section temperature is 1140-1150°C, and the soaking section temperature is 1160°C; keep warm in the soaking section for 2 hours. During rolling, the starting rolling temperature is 1050-1150°C, and the final rolling temperature is 900-950°C.

[0063] Step 2: saw the rod-shaped rolled piece into round bars, and use an air hammer to perform rough forging, fine forging, and trimming the round bars into forged balls. The starting forging temperature of the round bars is 1130-1165°C, and after forging, the surface temperature of the forged balls is 990-1020°C, and the forging time is 25-30s.

[0064] In addition, the centrifugal speed corresponding to the centrifugal environment in the ultrasonic megasonic centrifugal water quenching is 500-3300 r / min, the ultrasonic frequency of the ultrasonic wave is 20-100 kHz, and the megasonic frequency of the megasonic wave is greater than or equal to 800 kHz.

[0065] The yield strength of the rod-shaped rolled product is 667MPa and the tensile strength is 1059MPa. The diameter of the wear-resistant forged ball is 15cm and no quenching cracks occur during quenching.

[0066] Example 3

[0067] A high-efficiency heat treatment method for a wear-resistant forged ball comprises the following steps:

[0068] The forged ball is first heated to 1050°C and kept at this temperature for 45 minutes, then air-cooled to 810°C and kept at this temperature for 2 hours; then cooled to 780°C and subjected to ultrasonic megasonic centrifugal water quenching, wherein the quenching agent used in the ultrasonic megasonic centrifugal water quenching is water, and ultrasonic waves and megasonic waves simultaneously vibrate the forged ball and water in a centrifugal environment;

[0069] After that, the wear-resistant forged ball can be obtained by low temperature tempering at 210℃ for 3h.

[0070] Wherein, the method for making the forged ball comprises the following steps:

[0071] Step 1: The alloy raw materials are weighed according to the above ratio, and the forged ball is made of the following components in weight percentage:

[0072] C: 0.6%~0.7wt%; Mn: 0.85%~0.95wt%; Si: 0.5%~0.6wt%; P: ≤0.012%;

[0073] Cr: 0.3~0.35wt%; Ni: 0.1%~0.15%; Al: ≤0.02%; Ti: 1%~1.5%; the rest is Fe and unavoidable impurities.

[0074] The alloy raw materials are smelted in a smelting furnace, and the composition of the molten steel in the ladle in the smelting furnace is tested. After the test is qualified, the molten steel in the ladle is slag-stripped and left to stand until the temperature of the molten steel drops to 1545-1550℃, and then the molten steel is poured into a continuous casting machine to cast into a round billet; then the round billet is placed in a five-stage heating furnace for homogenization and rolled to obtain a rod-shaped rolled piece; the preheating section temperature in the five-stage heating furnace is 555-560℃, the heating section temperature is 790-810℃, the heating section temperature is 980-1000℃, the soaking section temperature is 1150-1160℃, and the soaking section temperature is 1160℃; keep warm in the soaking section for 2.5h. During rolling, the starting rolling temperature is 1050-1150℃, and the final rolling temperature is 900-950℃.

[0075] Step 2: saw the rod-shaped rolled piece into round bars, and use an air hammer to perform rough forging, fine forging, and trimming the round bars into forged balls. The starting forging temperature of the round bars is 1130-1165°C, and after forging, the surface temperature of the forged balls is 990-1020°C, and the forging time is 25-30s.

[0076] In addition, the centrifugal speed corresponding to the centrifugal environment in the ultrasonic megasonic centrifugal water quenching is 500-3300 r / min, the ultrasonic frequency of the ultrasonic wave is 20-100 kHz, and the megasonic frequency of the megasonic wave is greater than or equal to 800 kHz.

[0077] The yield strength of the rod-shaped rolled product is 669MPa and the tensile strength is 1068MPa. The diameter of the wear-resistant forged ball is 20cm and no quenching cracks occur during quenching.

[0078] Example 4

[0079] In Example 1, the wear-resistant forged ball high-efficiency heat treatment device is used to perform ultrasonic megasonic centrifugal water quenching on the forged ball. Figures 1 to 3 As shown, the wear-resistant forged ball efficient heat treatment device includes a water tank 10, a cylindrical metal screen 12 installed inside the water tank 10, a plurality of ultrasonic generating components 30, and a plurality of megasonic generating components 20. A hollow rotating shaft 14 is installed below the bottom of the water tank 10. The interior of the water tank 10 is divided by the metal screen 12 into a heat treatment chamber 16 and a sonic chamber 15 located between the side wall of the water tank 10 and the metal screen 12. The megasonic generating component 20 is provided with a rotating megasonic probe 21, and the ultrasonic generating component 30 is provided with a rotating ultrasonic probe 31. The lower sections of the rotating megasonic probe 21 and the rotating ultrasonic probe 31 are both arranged in the sonic chamber 15, and the upper ends of the rotating megasonic probe 21 and the rotating ultrasonic probe 31 are both arranged outside the sonic chamber 15.

[0080] The rotating megasonic probe 21 and the rotating ultrasonic probe 31 can both be purchased from Shanghai Jinmao Industrial Technology Co., Ltd. They are used to generate ultrasonic waves and megasonic waves into liquids, and they can rotate on their own.

[0081] A boss 13 is provided in the center of the heat treatment chamber 16, the outer periphery of the boss 13 is a rotating curved surface structure, and the cross section of the boss 13 is an arc-shaped structure concave inwardly; a core shaft 30 is integrally connected to the top of the boss 13, and the core shaft 30 is coaxially arranged with the boss 13, and the boss 13 includes a plurality of first cylindrical segments 31 and a second cylindrical segment 33, and a first rotating curved surface segment 32 is provided between two adjacent first cylindrical segments 31, and the height of the first rotating curved surface segment 32 is arranged in a geometric increase from bottom to top, and the side wall of the first rotating curved surface segment 32 is a rotating curved surface. The first rotating curved surface section 32 has a cross section that is an arc structure that is concave inwards, and the surface of the first rotating curved surface section 32 is a mirror surface; the diameter of the second cylindrical section 33 is greater than the diameter of the first cylindrical section 31, and a second rotating curved surface section 34 is provided between the second cylindrical section 33 and the uppermost first cylindrical section 31, and the side wall of the second rotating curved surface section 34 is a rotating curved surface structure, and the cross section of the second rotating curved surface section 34 is an arc structure that is concave inwards, and the surface of the second rotating curved surface section 34 is a mirror surface; generally, the surface roughness Ra of the mirror surface is less than 0.025 μm. A plurality of discharge valves 11 connected to the heat treatment chamber 16 are also provided below the bottom of the water tank 10.

[0082] When the quenching temperature is reduced from 800°C to 760-780°C, the forged ball is poured into the water tank 10, and the centrifugal speed corresponding to the centrifugal environment in the ultrasonic megasonic centrifugal water quenching is 500-3300r / min, that is, the speed of the water tank 10 is controlled to be 500-3300r / min; the ultrasonic frequency of the ultrasonic wave is 20-100kHz, that is, the ultrasonic frequency of the ultrasonic wave generated by the rotary ultrasonic probe 31 is 20-100kHz; the megasonic frequency of the megasonic wave is greater than or equal to 800kHz, that is, the megasonic frequency of the megasonic wave generated by the rotary megasonic probe 21 is greater than or equal to 800kHz. Through the combined effects of centrifugation, ultrasound, megasonics, etc., when the quenching temperature is lower than 800°C, the hardened layer thickness and hardness of the large-diameter wear-resistant forged ball can be significantly improved, and the probability of quenching cracking can be reduced.

[0083] It is well known in the art that when the quenching temperature is lowered, although the probability of quenching cracks can be significantly reduced, indicators such as the thickness and hardness of the hardened layer will also decrease significantly, and the quenching effect will deteriorate.

[0084] In this embodiment, at least three rotating ultrasonic probes 31 are provided, and a megasonic probe unit is provided between two adjacent rotating ultrasonic probes 31. The megasonic probe unit is composed of at least one rotating megasonic probe 21. The number of rotating megasonic probes 21 in the megasonic probe unit is reduced by one according to the direction of the water tank 10. For example, in this example, the number of rotating megasonic probes 21 in the megasonic probe unit is 4, 3, 2, and 1. The direction of the rotating megasonic probe 21 is opposite to the direction of the water tank 10, and the direction of the rotating ultrasonic probe 31 is the same as the direction of the water tank 10.

[0085] The speed of the water tank 10 is V s , in units of r / min; the rotational speeds of the rotary ultrasonic probe 31 and the rotary megasonic probe 21 are both 10r / min, 20r / min or 30r / min; when the rotary ultrasonic probe 31 is performing ultrasonic operation, the ultrasonic frequency is f US , 20kHz≤f US ≤100kHz; when the rotary megasonic probe 21 performs megasonic operation, the megasonic frequency is f MS , f MS ≥800kHz.

[0086] When 500r / min≤V s ≤1200r / min, V s =λf US 2 +θf MS ; 0.01<λ<1, 0.1≤θ≤1, λ, θ are correction coefficients, which are empirical values ​​and can be adjusted according to actual conditions; this formula is only an empirical formula and does not involve dimensional changes. For example:

[0087] Test group A1: The corresponding wear-resistant forged ball in Example 4 is marked as forged ball 1, and its diameter is 20 cm. US =27kHz,λ=0.63,f MS =980kHz,θ=0.5,V s =950r / min; quenching is carried out according to this process parameter.

[0088] Test group A2: Forged ball 2 (different from forged ball 1 only in diameter), with a diameter of 15 cm, corresponding to f US =38kHz,λ=0.34,f MS =1050kHz,θ=0.27,V s =775r / min; quenching is carried out according to this process parameter.

[0089] Test group A3: forged ball 3 (made of 60Mn), with a diameter of 20cm, corresponding to f US =53kHz,λ=0.13,f MS =830kHz,θ=0.38,V s =680r / min; quenching is carried out according to this process parameter.

[0090] When 1200r / min<V s ≤3300r / min, 79kHz≤f US ≤100kHz, the larger the diameter of the wear-resistant forged ball, the higher the f US The larger the V s =βf MS , 1≤β≤2, β is the correction coefficient, which is an empirical value and can be adjusted according to actual conditions; this formula is only an empirical formula and does not involve dimensional changes. For example:

[0091] Test group A4: forged ball 4 (same material as forged ball 1), with a diameter of 23 cm, corresponding to f US =88kHz, f MS =1750kHz, β=1.3, V s =2275r / min; quenching is carried out according to this process parameter.

[0092] Test group A5: forged ball 5 (made of 60Mn), with a diameter of 30cm, corresponding to f US =92kHz, f MS =1360kHz, β=1.7, V s =2310r / min; quenching is carried out according to this process parameter.

[0093] Test group A6: The corresponding wear-resistant forged ball in Example 4 is marked as forged ball 1, and its diameter is 20 cm. In some other embodiments, the corresponding f US =84kHz, f MS =2180kHz, β=1.5, V s =3270r / min; according to the process parameters, the quenching can achieve a hardened layer thickness of 8.3cm and a thickness-to-diameter ratio of 0.415.

[0094] Test group B1: The wear-resistant forged ball corresponding to Example 4 is marked as forged ball 1, and its diameter is 20 cm. If f US =20kHz, f MS =980kHz, V s =950r / min, quenching is carried out according to this process parameter.

[0095] Test group B2: The corresponding wear-resistant forged ball in Example 4 is marked as forged ball 1, and its diameter is 20 cm. US =27kHz, f MS =1000kHz, V s =950r / min, quenching is carried out according to this process parameter.

[0096] Test group B3: The corresponding wear-resistant forged ball in Example 4 is marked as forged ball 1, and its diameter is 20 cm. If f US =27kHz, f MS =980kHz, V s =1000r / min, quenching is carried out according to this process parameter.

[0097] Test group C1: The corresponding wear-resistant forged ball in Example 4 is marked as forged ball 1, and its diameter is 20 cm. If f US = 0kHz, that is, the rotary ultrasonic probe 31 is not started, V s =950r / min, even if f MS When the frequency varies within the range of 800 to 1000 kHz, the maximum hardness of the hardened layer does not exceed 60.5 HRC.

[0098] Test group C2: The corresponding wear-resistant forged ball in Example 4 is marked as forged ball 1, and its diameter is 20 cm. If f MS = 0kHz, that is, the rotary megasonic probe 21 is not started, V s =950r / min, even if f US It varies within the range of 20 to 50 kHz, and the thickness-to-diameter ratio does not exceed 0.28.

[0099] Comparative Example 1

[0100] The forged balls (all with a diameter of 20 cm) obtained by forging according to Example 1 were first heated to 1050°C and kept at this temperature for 30 minutes, then air-cooled to 800°C and kept at this temperature for 2 hours; water quenching was used, and if the quenching temperature was 800°C, control ball 1 was finally obtained; if the quenching temperature was 760°C, control ball 2 was finally obtained; then, low-temperature tempering was also performed at 210°C for 3 hours. Control ball 1 and control ball 2 were tested according to the "Characterization Test of Hardened Layer", and the results are shown in Table 1.

[0101] In the traditional water quenching test, it was found that for the forged ball obtained by forging in Example 1, the highest quenching temperature was 800°C. At this temperature, if the ball diameter was less than 10 cm, no quenching cracking would occur; if the ball diameter was 13 cm, the probability of quenching cracking was less than 5% (100 quenchings were counted, and the number of cracking caused by quenching was recorded). When the quenching temperature was 805°C and the ball diameter was equal to 10 cm, the probability of quenching cracking exceeded 90%. When the quenching temperature was 780°C, even if the ball diameter was equal to 50 cm, the probability of quenching cracking was 0; the lower the quenching temperature, the lower the hardness and thickness of the hardened layer.

[0102] Comparative Example 2

[0103] The forged balls (all with a diameter of 20 cm) forged from 60Mn material were first heated to 1050°C and kept warm for 30 minutes, then air-cooled to 800°C and kept warm for 2 hours; water quenching was adopted with a quenching temperature of 800°C; low-temperature tempering was performed at 210°C for 3 hours to finally obtain a reference ball; the reference ball was tested according to the "Characterization Test of Hardened Layer", and the results are shown in Table 1.

[0104] Table 1

[0105]

[0106] Comparative Example 3

[0107] The difference between this example and Example 4 is that there are a total of 12 rotary megasonic wave probes 21, and there are 3 rotary megasonic wave probes 21 in each megasonic wave probe unit, and the rest is the same as test group A1; the mass ratio of water in the water tank 10 to the forged ball 1 is 10:1, and the number of forged balls 1 is 200. It was finally found that the proportion of quenching cracks in this example was 29.5%. In test group A1, the proportion of quenching cracks was 0. The reason is that the impact intensity of the megasonic wave is too strong and concentrated, which may cause quenching cracks in some forged balls.

[0108] In addition, the rotating megasonic probe 21 and the rotating ultrasonic probe 31 must rotate, and the water vortex in the water tank 10 and the continuous reflection of the sound waves, under the combined effect of multiple conditions, the impact distribution acting on each forging ball can eventually tend to be uniform / dynamically balanced.

[0109] Comparative Example 4

[0110] The difference between this example and Example 4 is that there are 8 rotary megasonic probes 21 in total, and there are 2 rotary megasonic probes 21 in each megasonic probe unit, and the rest is the same as test group A1; the mass ratio of water in the water tank 10 to the forged ball 1 is 10:1, and the number of forged balls 1 is 200. It was finally found that the proportion of quenching cracks in this example was 17.5%. The reason is that the impact intensity of the megasonic wave is too concentrated, which may cause quenching cracks in some forged balls.

[0111] Comparative Example 5

[0112] The difference between this example and Example 4 is that the direction of the rotating megasonic probe 21 is the same as that of the water tank 10, and the rest is the same (according to the parameter process in the test group A1); according to the "Quenching Uniformity Characterization Test", S max1 =1.801, indicating that the uniformity of the hardened layer is poor.

[0113] In experimental group A1, S max1 =0.407<0.5, indicating that the uniformity of the surface hardness of a single wear-resistant forged ball is good, the uniformity of the hardened layer on the surface of the wear-resistant forged ball is good, and its service life is long.

[0114] Comparative Example 6

[0115] This example is different from Example 4 in that the mandrel 30 is not provided, and the rest is the same (according to the parameter process in the test group A1); according to the "Quenching Uniformity Characterization Test", S max2 =5.091.

[0116] In experimental group A1, S max2 =0.731<1.

[0117] The arrangement of the mandrel 30, especially the first rotating curved surface section 32 and the second rotating curved surface section 34, is for reflecting sound waves. Its special structural arrangement enables the sound waves to be gathered in the water tank 10 to the maximum extent; the arrangement of the first cylindrical section 31 prevents the wear-resistant forged ball from hitting the first rotating curved surface section 32. The height of the first rotating curved surface section 32 is arranged to increase geometrically from bottom to top, so that the sound waves can be better reflected back into the water tank 10 when reflected by the mandrel 30.

[0118] Comparative Example 7

[0119] The difference between this example and Example 4 is that the mandrel 30 is replaced by a cylindrical shaft, and the side wall of the cylindrical shaft is also a mirror surface, and the rest is the same (according to the parameter process in the test group A1); according to the "Quenching Uniformity Characterization Test", S max2 =4.783.

[0120] Comparative Example 8

[0121] The difference between this example and Example 4 is that the mandrel 30 is replaced by a frustum cone shaft, the side wall of which is also a mirror surface, and the rest is the same (according to the parameter process in the test group A1); according to the "Quenching Uniformity Characterization Test", S max2 =4.825.

[0122] In the above embodiment, the test was carried out according to the "Hardened Layer Characterization Test", and the specific method was as follows:

[0123] The sample ball (such as wear-resistant forged ball) is sliced ​​along the diameter direction using a wire cutting machine to obtain a test sample with a thickness of 1 cm for hardness measurement and metallographic analysis. The hardness is measured using a Rockwell hardness tester, and the metallographic analysis is performed using a metallographic microscope. The thickness of the hardened layer is determined by the distance from the surface of the wear-resistant forged ball to the semi-martensite structure area. The thickness-to-diameter ratio refers to the ratio of the thickness of the hardened layer to the diameter (ball diameter) of the sample ball. It should be noted that, taking test group A1 as an example, in order to ensure the stability of the results of this test, there was only one sample ball in the water tank during this test.

[0124] The test method of "Quenching Uniformity Characterization Test" is as follows:

[0125] 1. Randomly take a sample ball from the water tank, randomly mark 10 areas on the surface of the sample ball, measure the hardness of these 10 areas respectively, and obtain the surface hardness value of the hardened layer; calculate the standard deviation of the surface hardness values ​​of these 10 hardened layers to obtain S 1 ; Repeat this 5 times to find 5 groups of S 1 The maximum value in is S max1 ; S max1 It reflects the uniformity of the surface hardness of a single sample ball and can be used to characterize the quenching effect.

[0126] 2. Randomly take 10 sample balls from the water tank, measure and record the maximum hardness of each hardened layer, and calculate the standard deviation of these 10 sets of data, expressed as S 2 Indicates; repeat this 5 times and find 5 groups of S 2 The maximum value in is S max2 ; if S max2 The larger the value, the less uniform the distribution of the hardening effect of the sample balls of the same batch quenched in the water tank, resulting in greater fluctuations in the quenching quality between different sample balls, which is not conducive to ensuring the stability and consistency of the quality of the same batch of products.

[0127] It should be noted that, taking test group A1 as an example, in this test, there are 100 sample balls in the water tank, and the mass ratio of water in the water tank to the sample balls is 10:1.

[0128] In the present invention, the hardenability of water quenching can be significantly improved by combining ultrasonic waves, megasonic waves, centrifugal force, etc., thereby significantly improving the thickness of the hardened layer (that is, the thickness-to-diameter ratio).

Claims

1. A wear-resistant forged ball efficient heat treatment method, characterized in that: The following steps are involved: The forged ball is first heated to 1050°C, kept at this temperature for 30-45 minutes, then air-cooled to 800°C, kept at this temperature for 2 hours; then cooled to 760-780°C, and subjected to ultrasonic megasonic centrifugal water quenching, wherein the quenching agent used in the ultrasonic megasonic centrifugal water quenching is water, and ultrasonic waves and megasonic waves simultaneously vibrate the forged ball and water in the centrifugal environment; After that, the wear-resistant forged ball can be obtained by low temperature tempering at 210℃ for 3h; The method for making the forged ball comprises the following steps: Step 1, smelting the alloy raw material in a smelting furnace, and after slagging and standing, using a continuous casting machine to cast into a round ingot; then placing the round ingot in a five-stage heating furnace for homogenization, and rolling to obtain a rod-shaped rolled piece; Step 2, sawing the rod-shaped rolled piece into round bars, and using an air hammer to perform rough forging, fine forging, and trimming the round bars into forged balls; The centrifugal speed corresponding to the centrifugal environment in the ultrasonic megasonic centrifugal water quenching is 500-3300 r / min, the ultrasonic frequency of the ultrasonic wave is 20-100 kHz, and the megasonic frequency of the megasonic wave is greater than or equal to 800 kHz.

2. A wear-resistant forged ball high-efficiency heat treatment method according to claim 1, characterized in that: In step 1, a forged ball is made from the following components in weight percentage: C: 0.6%~0.7wt%; Mn: 0.85%~0.95wt%; Si: 0.5%~0.6wt%; P: ≤0.012%; Cr: 0.3~0.35wt%; Ni: 0.1%~0.15%; Al: ≤0.02%; Ti: 1%~1.5%; the rest is Fe and unavoidable impurities; In step 1, the alloy raw materials are weighed according to the above ratio.

3. The high-efficiency heat treatment method for wear-resistant forged balls according to claim 1, characterized in that: In step 1, the composition of the molten steel in the ladle in the smelting furnace is tested. After passing the test, the molten steel in the ladle is deslagging and allowed to stand until the temperature of the molten steel drops to 1535~1550℃, and then the molten steel is poured into the continuous casting machine for casting.

4. A wear-resistant forged ball high-efficiency heat treatment method according to claim 1, characterized in that: In step 1, the temperature of the preheating section in the five-section heating furnace is 550~560℃, the temperature of the heating section is 700~810℃, the temperature of the heating section is 950~1000℃, the temperature of the aquaponics section is 1130~1160℃, and the temperature of the aquaponics section is 1160℃; the aquaponics section is kept warm for 2~2.5h.

5. The high-efficiency heat treatment method for wear-resistant forged balls according to claim 1, characterized in that: In step 1, during rolling, the starting rolling temperature is 1050-1150°C, and the finishing rolling temperature is 900-950°C.

6. A wear-resistant forged ball high-efficiency heat treatment method according to claim 1, characterized in that: In step 2, the starting forging temperature of the round bar is 1130~1165℃. After forging, the surface temperature of the forging ball is 990~1020℃, and the forging time is 25~30s.

7. A wear-resistant forged ball high-efficiency heat treatment device, characterized in that: Used to perform ultrasonic megasonic centrifugal water quenching on forged balls, the wear-resistant forged ball high-efficiency heat treatment device comprises a water tank (10), a cylindrical metal screen (12) installed inside the water tank (10), a plurality of ultrasonic generating components (30), and a plurality of megasonic generating components (20); a hollow rotating shaft (14) is installed below the bottom of the water tank (10); the interior of the water tank (10) is divided by the metal screen (12) into a heat treatment chamber (16) and a sound wave chamber (15) located between the side wall of the water tank (10) and the metal screen (12); the megasonic generating component (20) is provided with a rotating megasonic probe (21); the ultrasonic generating component (30) is provided with a rotating ultrasonic probe (31); the lower sections of the rotating megasonic probe (21) and the rotating ultrasonic probe (31) are both arranged in the sound wave chamber (15); and the upper ends of the rotating megasonic probe (21) and the rotating ultrasonic probe (31) are both arranged outside the sound wave chamber (15); A boss (13) is arranged at the center of the heat treatment chamber (16); the outer periphery of the boss (13) is a rotational curved surface structure; the cross section of the boss (13) is an inwardly concave arc structure; a core shaft (30) is integrally connected to the top of the boss (13); the core shaft (30) and the boss (13) are coaxially arranged; the boss (13) comprises a plurality of first cylindrical segments (31) and second cylindrical segments (33); a first rotational curved surface segment (32) is arranged between two adjacent first cylindrical segments (31); the height of the first rotational curved surface segment (32) is arranged to increase in geometric proportion from bottom to top; the side wall of the first rotational curved surface segment (32) is a rotational curved surface structure; The cross section of a rotating curved surface segment (32) is an arc-shaped structure that is concave inwards, and the surface of the first rotating curved surface segment (32) is a mirror surface; the diameter of the second cylindrical segment (33) is greater than the diameter of the first cylindrical segment (31), a second rotating curved surface segment (34) is provided between the second cylindrical segment (33) and the uppermost first cylindrical segment (31), the side wall of the second rotating curved surface segment (34) is a rotating curved surface structure, the cross section of the second rotating curved surface segment (34) is an arc-shaped structure that is concave inwards, and the surface of the second rotating curved surface segment (34) is a mirror surface; a plurality of discharge valves (11) that are connected to the heat treatment chamber (16) are also provided below the bottom of the water tank (10); At least three rotating ultrasonic probes (31) are provided, and a megasonic probe unit is provided between two adjacent rotating ultrasonic probes (31). The megasonic probe unit is composed of at least one rotating megasonic probe (21). The number of rotating megasonic probes (21) in the megasonic probe unit is arranged to decrease in sequence according to the direction of rotation of the water tank (10). The rotation direction of the rotating megasonic probes (21) is opposite to the direction of rotation of the water tank (10), and the rotation direction of the rotating ultrasonic probes (31) is the same as the direction of rotation of the water tank (10).

8. The wear-resistant forged ball high-efficiency heat treatment device according to claim 7 is characterized in that: The speed of the water tank is V s , unit is r / min; When the rotary ultrasonic probe performs ultrasonic operation, the ultrasonic frequency is f US , 20kHz≤f US ≤100kHz; When the rotary megasonic wave probe performs megasonic operation, the megasonic frequency is f MS , f MS ≥800kHz; When 500r / min≤V s ≤1200r / min, V s =λf US 2 +θf MS , V s The unit is r / min, f US The unit is kHz, f MS The unit is kHz; 0.01<λ<1, 0.1≤θ≤1, λ and θ are correction coefficients; When 1200r / min<V s ≤3300r / min, 79kHz≤f US ≤100kHz, f US Positively correlated with the diameter of the wear-resistant forged ball, V s =βf MS , V s The unit is r / min, f US The unit is kHz, f MS The unit is kHz; 1≤β≤2, β is the correction coefficient.

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