Method for producing high-chromium grinding balls by using oil-like quenching liquid

Abstract

The invention discloses a method for producing a high-chromium grinding ball by using an oil-like quenching liquid, which comprises the following steps: austenitizing a high-chromium grinding ball blank, quenching by using the oil-like quenching liquid, and tempering to obtain the high-chromium grinding ball, wherein the oil-like quenching liquid is prepared from the following raw materials in parts by weight: 13 to 15 parts of polyvinylpyrrolidone, 4 to 6 parts of sodium carboxymethyl cellulose, 1 to 2 parts of phytic acid and 77 to 82 parts of water. According to the invention, nano VC, Mo, Ni and oil-like quenching liquid in proper proportion are selected, and a proper heat treatment process is combined, so that the hardness of the grinding ball can be improved, and good toughness can be maintained.

Description

Technical Field

[0001] The invention relates to the technical field of wear-resistant balls, and in particular to a method for producing high-chromium grinding balls by using an oil-like quenching liquid. Background Art

[0002] High chromium cast iron grinding balls have good wear resistance, and heat treatment is often used to improve the wear resistance of the grinding balls. During the heat treatment of high chromium cast iron grinding balls, quenching oil is often used as the cooling medium, but traditional quenching oil is easy to catch fire, there is oil smoke at the use site, and there are greater risks to safety, environmental protection, and occupational health. In addition, the martensite transformation in the high chromium grinding balls after oil quenching is incomplete, and the hardness is low, generally 58-62HRC, which cannot meet the market development needs.

[0003] At present, water-soluble quenching media (such as polyalkylene glycol (PAG) quenching liquid) are often used to replace quenching oil. PAG quenching liquid has obvious reverse solubility. When quenching, the solution near the surface of the grinding ball can instantly reach above the reverse solubility temperature. At this time, in addition to forming some steam bubble cores on the surface of the grinding ball, some PAG will precipitate from the solution; these PAGs will destroy the steam bubble cores due to thermal motion and infiltration of the workpiece and adhere to the surface of the grinding ball. As the temperature decreases and the cooling time increases, a certain thickness of water-containing polymer isolation film will be formed on the surface of the grinding ball. At a specific temperature, the isolation film and the steam bubbles inside and outside the isolation film will explode, forming the maximum cooling rate. In the subsequent convection stage, due to the presence of PAG solutes, the heat conductivity is lower than that of water, so it has a lower cooling rate in the later stage of quenching.

[0004] However, PAG quenching liquid is commonly used for ordinary carbon steel, medium and low alloy steel. When it is used to quench high chromium cast iron grinding balls, cracks are prone to occur, and the toughness of the grinding balls is low; and in the later stage of quenching, secondary explosions usually occur near the surface of the grinding balls, resulting in accelerated cooling speed in the later stage of quenching, and ultimately reducing the performance of the grinding balls. Summary of the invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a method for producing high chromium grinding balls using an oil-like quenching liquid. The present invention can improve the hardness of the grinding balls and maintain good toughness by selecting appropriate proportions of nano VC, Mo, Ni, oil-like quenching liquid, and combining appropriate heat treatment processes.

[0006] The present invention provides a method for producing high chromium grinding balls using an oil-like quenching liquid, comprising the following steps: taking a high chromium grinding ball blank, austenitizing it, then quenching it with an oil-like quenching liquid, and tempering it to obtain a high chromium grinding ball;

[0007] The raw materials of the oil-like quenching liquid include, by weight: 13-15 parts of polyvinyl pyrrolidone, 4-6 parts of sodium carboxymethyl cellulose, 1-2 parts of phytic acid, and 77-82 parts of water.

[0008] Preferably, the molecular weight of polyvinyl pyrrolidone is 8000-10000.

[0009] Preferably, the raw materials of the high chromium grinding ball blank include, by weight percentage: C 2.0-3.6%, Si 0.2-2.0%, Mn 0.3-1.5%, Cr 10-15%, Mo 1-1.5%, Ni 0.6-0.8%, nano VC 0.02-0.025%, and the balance is Fe and unavoidable impurities.

[0010] More preferably, the raw materials of the high chromium grinding ball blank include, by weight percentage: C 2.4-2.5%, Si 0.5-0.6%, Mn 0.6-0.8%, Cr 12-14%, Mo 1-1.5%, Ni 0.6-0.8%, nano VC 0.02-0.025%, and the balance is Fe and unavoidable impurities.

[0011] The invention selects polyvinyl pyrrolidone and sodium carboxymethyl cellulose to cooperate with each other in an appropriate ratio, so as to improve the cooling speed in the early stage of quenching and promote more austenite to transform into martensite; and adds appropriate amounts of nano VC and Mo to cooperate with each other, so as to improve the content of carbides and Cr elements in martensite during the transformation process of austenite into martensite, thereby improving the hardness of martensite, and can refine carbides and residual austenite to make them dispersedly distributed, and cooperate with Ni to maintain the toughness of grinding balls; in addition, in the late stage of quenching, polyvinyl pyrrolidone and sodium carboxymethyl cellulose cooperate with each other, so as to reduce the cooling speed, and combine with Mo and Ni to improve the hardenability of grinding balls, so as to improve the quenching uniformity and stress distribution uniformity of grinding balls in the late stage of quenching, and avoid the problem that high chromium grinding balls are easy to crack during quenching.

[0012] Preferably, the temperature of the oil-like quenching liquid is 20-60°C.

[0013] Preferably, the quenching cools the grinding balls to a temperature of 20-60°C.

[0014] The oil-like quenching liquid of the present invention can cool the grinding balls to 20-60° C., further increase the transformation amount of martensite, and further improve the wear resistance; the phytic acid in the oil-like quenching liquid can also play an anti-rust protective role; in addition, polyvinyl pyrrolidone and sodium carboxymethyl cellulose are matched with each other in a suitable proportion to avoid the problem of secondary explosion in the late stage of polymer quenching, thereby improving the quenching effect.

[0015] Preferably, the austenitizing temperature is 930-1050° C. and the time is 2-4 h.

[0016] Preferably, the tempering procedure is: keep at 450-500°C for 2-3h, then keep at 180-220°C for 2-3h, and then air cool to room temperature.

[0017] The present invention selects appropriate austenitization parameters to make austenite in an unstable state, making it easier for austenite to transform into martensite during quenching; and the two-stage tempering method can further eliminate stress and further improve the toughness of the grinding ball.

[0018] The present invention selects nano VC, Mo, Ni in appropriate proportions, an oil-like quenching liquid, and combines appropriate heat treatment processes to increase the amount of martensite transformation and the content of carbides and Cr elements in martensite, thereby increasing the hardness of the grinding balls, and can refine carbides and residual austenite to make them dispersed, so that the grinding balls maintain good toughness. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is described in detail below through specific embodiments.

[0020] Example 1

[0021] A method for producing high chromium grinding balls using an oil-like quenching liquid comprises the following steps:

[0022] The raw materials of the high chromium grinding ball blank with a diameter of 80 mm include, by weight percentage: C 2.0%, Si 0.2%, Mn 0.3%, Cr 15%, Mo 1.2%, Ni 0.7%, nano VC 0.02%, and the balance is Fe and unavoidable impurities;

[0023] Take the high chromium grinding ball blank, keep it at 1050℃ for 3h for austenitization, and then quench it with oil-like quenching liquid at 60℃ to cool the grinding ball to 60℃;

[0024] The raw materials of the oil-like quenching liquid include, by weight: 14 parts of polyvinyl pyrrolidone with a molecular weight of 8000, 4 parts of sodium carboxymethyl cellulose, 1 part of phytic acid, and 81 parts of water;

[0025] The mixture was kept at 480°C for 2.5 h, then kept at 200°C for 2.5 h, and then air-cooled to room temperature to obtain high chromium grinding balls.

[0026] Example 2

[0027] A method for producing high chromium grinding balls using an oil-like quenching liquid comprises the following steps:

[0028] The raw materials of the high chromium grinding ball blank with a diameter of 80 mm include, by weight percentage: C 3.6%, Si 2.0%, Mn 1.5%, Cr 10%, Mo 1.5%, Ni 0.8%, nano VC 0.025%, and the balance is Fe and unavoidable impurities;

[0029] Take the high chromium grinding ball blank, keep it at 1030℃ for 3h for austenitization, and then quench it with oil-like quenching liquid at 20℃ to cool the grinding ball to 20℃;

[0030] The raw materials of the oil-like quenching liquid include, by weight: 14 parts of polyvinyl pyrrolidone with a molecular weight of 8000, 5 parts of sodium carboxymethyl cellulose, 1 part of phytic acid, and 80 parts of water;

[0031] The mixture was kept at 470°C for 3 h, then kept at 220°C for 2 h, and then air-cooled to room temperature to obtain high chromium grinding balls.

[0032] Example 3

[0033] A method for producing high chromium grinding balls using an oil-like quenching liquid comprises the following steps:

[0034] The raw materials of the high chromium grinding ball blank with a diameter of 80 mm include, by weight percentage: C 2.4%, Si 0.6%, Mn 0.6%, Cr 14%, Mo 1%, Ni 0.8%, nano VC 0.02%, and the balance is Fe and unavoidable impurities;

[0035] Take the high chromium grinding ball blank, keep it at 1050℃ for 2h for austenitization, and then quench it with oil-like quenching liquid at 20℃ to cool the grinding ball to 25℃;

[0036] The raw materials of the oil-like quenching liquid include, by weight: 15 parts of polyvinyl pyrrolidone with a molecular weight of 8000, 4 parts of sodium carboxymethyl cellulose, 2 parts of phytic acid, and 79 parts of water;

[0037] The mixture was kept at 500°C for 2 h, then kept at 220°C for 2 h, and then air-cooled to room temperature to obtain high chromium grinding balls.

[0038] Example 4

[0039] A method for producing high chromium grinding balls using an oil-like quenching liquid comprises the following steps:

[0040] The raw materials of the high chromium grinding ball blank with a diameter of 80 mm include, by weight percentage: C 2.5%, Si 0.5%, Mn 0.8%, Cr 12%, Mo 1.5%, Ni 0.6%, nano VC 0.025%, and the balance is Fe and unavoidable impurities;

[0041] Take the high chromium grinding ball blank, keep it at 930℃ for 4h for austenitization, and then quench it with oil-like quenching liquid at 30℃ to cool the grinding ball to 30℃;

[0042] The raw materials of the oil-like quenching liquid include, by weight: 13 parts of polyvinyl pyrrolidone with a molecular weight of 10,000, 6 parts of sodium carboxymethyl cellulose, 1 part of phytic acid, and 80 parts of water;

[0043] The mixture was kept at 450°C for 3 h, then kept at 180°C for 3 h, and then air-cooled to room temperature to obtain high chromium grinding balls.

[0044] Example 5

[0045] A method for producing high chromium grinding balls using an oil-like quenching liquid comprises the following steps:

[0046] The raw materials of the high chromium grinding ball blank with a diameter of 80 mm include, by weight percentage: C 2.45%, Si 0.55%, Mn 0.7%, Cr 13%, Mo 1.2%, Ni 0.7%, nano VC 0.023%, and the balance is Fe and unavoidable impurities;

[0047] Take the high chromium grinding ball blank, keep it at 1010℃ for 3h for austenitization, and then quench it with oil-like quenching liquid at 40℃ to cool the grinding ball to 30℃;

[0048] The raw materials of the oil-like quenching liquid include, by weight: 14 parts of polyvinyl pyrrolidone with a molecular weight of 10,000, 5 parts of sodium carboxymethyl cellulose, 1 part of phytic acid, and 80 parts of water;

[0049] The mixture was kept at 470°C for 2.5 h, then kept at 200°C for 2.5 h, and then air-cooled to room temperature to obtain high chromium grinding balls.

[0050] Comparative Example 1

[0051] A method for producing high chromium grinding balls comprises the following steps:

[0052] Replace "sodium carboxymethyl cellulose" with "polyvinyl pyrrolidone", and the rest is the same as Example 5.

[0053] Comparative Example 2

[0054] A method for producing high chromium grinding balls comprises the following steps:

[0055] Replace "polyvinyl pyrrolidone" with "sodium carboxymethyl cellulose", and the rest is the same as Example 5.

[0056] Comparative Example 3

[0057] A method for producing high chromium grinding balls comprises the following steps:

[0058] The raw materials of the oil-like quenching liquid include, by weight: 19 parts of polyalkylene glycol with a molecular weight of 10,000, 1 part of phytic acid, and 80 parts of water. The rest are the same as in Example 5.

[0059] Comparative Example 4

[0060] A method for producing high chromium grinding balls comprises the following steps:

[0061] It does not contain Mo and nano-VC, and the rest is the same as Example 5.

[0062] Comparative Example 5

[0063] A method for producing high chromium grinding balls comprises the following steps:

[0064] It does not contain Ni, and the rest is the same as Example 5.

[0065] The mechanical properties of the grinding balls obtained in Examples 1-5 and Comparative Examples 1-5 were tested, and the results are shown in Table 1.

[0066] Table 1 Test results

[0067]

[0068]

[0069] It can be seen from the above table that the grinding balls prepared by the method of the present invention have good hardness and toughness, and will not have the problem of secondary explosion during quenching.

[0070] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for producing high chromium grinding balls using an oil-like quenching liquid, characterized in that: The method comprises the following steps: taking a high chromium grinding ball blank, austenitizing it, then quenching it with an oil-like quenching liquid, and tempering it to obtain a high chromium grinding ball; The raw materials of the oil-like quenching liquid include, by weight: 13-15 parts of polyvinyl pyrrolidone, 4-6 parts of sodium carboxymethyl cellulose, 1-2 parts of phytic acid, and 77-82 parts of water.

2. The method for producing high chromium grinding balls using oil-like quenching liquid according to claim 1, characterized in that: The molecular weight of polyvinyl pyrrolidone is 8000-10000.

3. The method for producing high chromium grinding balls using oil-like quenching liquid according to claim 1 or 2, characterized in that: The raw materials of the high chromium grinding ball blank include, by weight percentage: C 2.0-3.6%, Si 0.2-2.0%, Mn 0.3-1.5%, Cr 10-15%, Mo 1-1.5%, Ni 0.6-0.8%, nano VC 0.02-0.025%, and the balance is Fe and unavoidable impurities.

4. The method for producing high chromium grinding balls using oil-like quenching liquid according to any one of claims 1 to 3, characterized in that: The temperature of the oil-like quenching liquid is 20-60°C.

5. The method for producing high chromium grinding balls using oil-like quenching liquid according to any one of claims 1 to 4, characterized in that: The quenching process cools the grinding balls to 20-60°C.

6. The method for producing high chromium grinding balls using oil-like quenching liquid according to any one of claims 1 to 5, characterized in that: The austenitizing temperature is 930-1050°C and the time is 2-4h.

7. The method for producing high chromium grinding balls using oil-like quenching liquid according to any one of claims 1 to 6, characterized in that: The tempering procedure is: keep at 450-500℃ for 2-3h, then keep at 180-220℃ for 2-3h, and then air cool to room temperature.

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