Heat treatment process for wear-resistant gears

Abstract

The application relates to the technical field of metal heat treatment, and discloses a heat treatment process of a wear-resistant gear, which comprises the following steps: preheating the gear, normalizing, quenching, low-temperature tempering treatment, and obtaining the wear-resistant gear; the low-temperature tempering treatment comprises first low-temperature tempering treatment and second low-temperature tempering treatment; the first low-temperature tempering treatment is to heat the gear to 170-190 DEG C at a heating rate of 25-30 DEG C / s, keep the temperature for 50-65 min, and air cool; the second low-temperature tempering treatment is to heat the gear to 160-170 DEG C at a heating rate of 35-40 DEG C / s, keep the temperature for 30-45 min, and air cool. Through the technical scheme, the problem of poor wear resistance of the gear in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the field of metal heat treatment technology, and more specifically, to a heat treatment process for wear-resistant gears. Background Technology

[0002] Gears, as core transmission components in various equipment and mechanical systems, transmit power based on the frictional force generated when their tooth profiles mesh. When two gears mesh, the frictional force generated by the contact of their tooth surfaces efficiently transmits power from the drive shaft to the driven shaft. Furthermore, depending on the gear configuration and meshing method, different directions and speeds of motion can be achieved, making them fundamental components for power and motion conversion in mechanical systems. The wear resistance of gears directly determines the overall service life and operational stability of the equipment. During long-term transmission, the tooth surface continuously endures friction, compression, and impact loads. Existing technologies suffer from insufficient wear resistance in gears, leading to gradual wear, decreased precision, and ultimately a sharp reduction in tooth surface strength. When wear accumulates to a certain extent, it can easily induce serious failures such as tooth breakage and tooth surface spalling, causing irreversible damage to the gear itself and potentially paralyzing the entire transmission system, even leading to equipment downtime, production interruptions, and other chain losses. Therefore, a wear-resistant gear is needed to ensure the long-term reliable operation of mechanical systems and reduce the risk of failure and maintenance costs. Summary of the Invention

[0003] This invention proposes a heat treatment process for wear-resistant gears, which solves the problem of poor wear resistance of gears in related technologies.

[0004] The technical solution of the present invention is as follows:

[0005] This invention proposes a heat treatment process for wear-resistant gears, comprising the following steps:

[0006] The gear is preheated, normalized, quenched, and then subjected to low-temperature tempering to obtain a wear-resistant gear.

[0007] The low-temperature tempering includes a first low-temperature tempering treatment and a second low-temperature tempering treatment.

[0008] The first low-temperature tempering treatment involves heating the temperature to 170-190°C at a heating rate of 25-30°C / s, holding it at that temperature for 50-65 minutes, and then air cooling.

[0009] The second low-temperature tempering treatment involves heating the temperature to 160-170°C at a rate of 35-40°C / s, holding it at that temperature for 30-45 minutes, and then air cooling.

[0010] In the heat treatment process of the wear-resistant gear of this invention, two low-temperature tempering treatments are used to precisely control the microstructure of the gear, so that the gear exhibits excellent performance and improves the service life of the gear.

[0011] As a further technical solution, the preheating temperature is 350~400℃, and the heat preservation time is 30~35min.

[0012] As a further technical solution, the normalizing temperature is 1050~1150℃, and the holding time is 35~65min.

[0013] As a further technical solution, the quenching temperature is 900~1000℃ and the holding time is 35~65min.

[0014] As a further technical solution, the low-temperature tempering treatment also includes nitriding treatment.

[0015] As a further technical solution, the nitriding treatment temperature is 460~580℃ and the time is 2220~3480min.

[0016] As a further technical solution, the nitriding treatment includes primary nitriding treatment, secondary nitriding treatment, and tertiary nitriding treatment.

[0017] As a further technical solution, the nitriding treatment is gas nitriding.

[0018] In the heat treatment process of the wear-resistant gears of this invention, gas nitriding is used during nitriding. Gas nitriding can significantly improve the overall performance of the gears, ensure stable operation of the gears under various harsh conditions, and improve the overall performance and reliability of the equipment.

[0019] As a further technical solution, the gas used in the nitriding process includes ammonia.

[0020] As a further technical solution, the ammonia gas flow rate is 12~20m³. 3 / h.

[0021] As a further technical solution, the temperature of the primary nitriding treatment is 460~500℃, the time is 600~900min, and the ammonia gas flow rate is 12~14m³. 3 / h.

[0022] As a further technical solution, the temperature of the secondary nitriding treatment is 510~550℃, the time is 1440~2160min, and the ammonia gas flow rate is 18~20m³. 3 / h.

[0023] As a further technical solution, the temperature of the three nitriding treatments is 555~580℃, the time is 180~420min, and the ammonia gas flow rate is 15~17m³. 3 / h.

[0024] In the heat treatment process of the wear-resistant gears of this invention, a three-stage nitriding process is used, and the ammonia gas flow rate during the first nitriding treatment is controlled to be 12-14 mg / L. 3 The ammonia flow rate during the secondary nitriding treatment is 18~20 m³ / h. 3 The ammonia flow rate during the three-stage nitriding treatment is 15~17 m³ / h. 3 By controlling the nitrogen flow rate at each stage, the nitriding layer can be precisely controlled, improving the consistency and stability of gear quality, and further enhancing the wear resistance and hardness of the gear.

[0025] As a further technical solution, the wear-resistant gear is composed of the following components by weight percentage: C 0.45%~0.75%, Si 0.05%~0.35%, Mn 0.55%~0.85%, Cr 1.6%~1.8%, Ni 1.2%~1.5%, P 0.004%~0.018%, S 0.006%~0.022%, Mo 0.22%~0.35%, Al 0.03%~0.05%, Cu 0.04%~0.23%, Nb 0.15%~0.20%, Ti 0.002%~0.006%, Sb 0.001%~0.004%, N 0.003%~0.013%, V 0.01%~0.03%, with the remainder being Fe and other unavoidable impurities.

[0026] The working principle and beneficial effects of this invention are as follows:

[0027] In this invention, the heating rate of the two low-temperature tempering processes in the heat treatment of the gear is controlled. The heating rate of the first low-temperature tempering is 25~30℃ / s, and the heating rate of the second low-temperature tempering is 35~40℃ / s, which significantly improves the wear resistance of the gear. The heating rate of 25~30℃ / s in the first low-temperature tempering ensures the stability of the material microstructure, and the heating rate of 35~40℃ / s in the second low-temperature tempering further optimizes the microstructure, thereby improving the wear resistance of the gear and extending its service life. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] A heat treatment process for wear-resistant gears includes the following steps: placing the gear in a heating device, first heating it to 350°C for preheating, and holding it at that temperature for 35 minutes; after preheating, continuing to heat it to 1050°C for normalizing, holding it at that temperature for 65 minutes, and then air cooling.

[0031] After normalizing, the gears are quenched. During quenching, the temperature is raised to 1000℃ and held for 35 minutes, then oil-cooled to room temperature.

[0032] After quenching, the gear undergoes two low-temperature tempering treatments. The first low-temperature tempering treatment involves heating the gear to 170°C at a heating rate of 25°C / s, holding it at that temperature for 65 minutes, and then air-cooling it. The second low-temperature tempering treatment involves heating the gear to 160°C at a heating rate of 35°C / s, holding it at that temperature for 45 minutes, and then air-cooling it to obtain a wear-resistant gear.

[0033] Example 2

[0034] A heat treatment process for wear-resistant gears includes the following steps: placing the gear in a heating device, first heating it to 400℃ for preheating, and holding it at that temperature for 30 minutes; after preheating, continuing to heat it to 1150℃ for normalizing, holding it at that temperature for 35 minutes, and then air cooling.

[0035] After normalizing, the gears are quenched. During quenching, the temperature is raised to 900℃ and held for 65 minutes. Then, the gears are oil-cooled to room temperature.

[0036] After quenching, the gear undergoes two low-temperature tempering treatments. The first low-temperature tempering treatment involves heating the gear to 190°C at a heating rate of 30°C / s, holding it at that temperature for 50 minutes, and then air cooling. The second low-temperature tempering treatment involves heating the gear to 170°C at a heating rate of 40°C / s, holding it at that temperature for 30 minutes, and then air cooling to obtain the pre-treated gear.

[0037] The pretreated gears were placed in a nitriding apparatus, and ammonia gas (20m³) was introduced at 460°C. 3 The nitriding treatment time was 3480 min, and the gears were air-cooled after treatment to obtain wear-resistant gears.

[0038] Example 3

[0039] A heat treatment process for wear-resistant gears includes the following steps: placing the gear in a heating device, first heating it to 380℃ for preheating, and holding it at that temperature for 33 minutes; after preheating, continuing to heat it to 1100℃ for normalizing, holding it at that temperature for 45 minutes, and then air cooling.

[0040] After normalizing, the gears are quenched. During quenching, the temperature is raised to 950℃ and held for 50 minutes, then oil-cooled to room temperature.

[0041] After quenching, the gear undergoes two low-temperature tempering treatments. The first low-temperature tempering treatment involves heating the gear to 180°C at a heating rate of 28°C / s, holding it at that temperature for 55 minutes, and then air cooling. The second low-temperature tempering treatment involves heating the gear to 165°C at a heating rate of 37°C / s, holding it at that temperature for 35 minutes, and then air cooling to obtain the pre-treated gear.

[0042] The pretreated gears were placed in a nitriding apparatus, and ammonia gas (20m³) was introduced at 460°C. 3 The nitriding treatment time was 3480 min, and the gears were air-cooled after treatment to obtain wear-resistant gears.

[0043] Example 4

[0044] The only difference between this embodiment and Embodiment 3 is that the heating rate of the first low-temperature tempering treatment is 30°C / s.

[0045] Example 5

[0046] The only difference between this embodiment and Embodiment 3 is that the heating rate of the first low-temperature tempering treatment is 25°C / s.

[0047] Example 6

[0048] The only difference between this embodiment and Embodiment 3 is that the heating rate of the second low-temperature tempering is 40°C / s.

[0049] Example 7

[0050] The only difference between this embodiment and Embodiment 3 is that the heating rate of the second low-temperature tempering is 35°C / s.

[0051] Example 8

[0052] The only difference between this embodiment and Embodiment 6 is the process parameters during nitriding: the pretreated gear is placed in a nitriding device, and ammonia gas (injection rate of 12m³) is introduced at 580°C. 3 The nitriding treatment time was 2220 min, and the gears were air-cooled after treatment to obtain wear-resistant gears.

[0053] Example 9

[0054] The only difference between this embodiment and Embodiment 6 is the use of three nitriding treatments: the pretreated gear is placed in a nitriding device, the temperature of the first nitriding treatment is 460℃, the time is 900 min, and the ammonia gas flow rate is 10 m³. 3 / h; the second nitriding treatment was carried out at a temperature of 510℃ for 2160 min, with an ammonia flow rate of 12m³ / h. 3 / h; the third nitriding treatment was carried out at a temperature of 555℃ for 420 min, with an ammonia flow rate of 18m³. 3 / h, air cooling, to obtain wear-resistant gears.

[0055] Example 10

[0056] The only difference between this embodiment and Embodiment 6 is the use of three nitriding treatments: the pretreated gear is placed in a nitriding device, the temperature of the first nitriding treatment is 500℃, the time is 600min, and the ammonia gas flow rate is 10m³. 3 / h; the second nitriding treatment was carried out at a temperature of 550℃ for 1440 min, with an ammonia flow rate of 12m³ / h. 3 / h; the third nitriding treatment was performed at a temperature of 580℃ for 180 min, with an ammonia flow rate of 18 m³ / h. 3 / h, air cooling, to obtain wear-resistant gears.

[0057] Example 11

[0058] The only difference between this embodiment and Embodiment 6 is the use of three nitriding treatments: the pretreated gear is placed in a nitriding device, the temperature of the first nitriding treatment is 480℃, the time is 700min, and the ammonia gas flow rate is 10m³. 3 / h; the second nitriding treatment was carried out at a temperature of 520℃ for 1900 min, with an ammonia flow rate of 17m³. 3 / h; the third nitriding treatment was performed at a temperature of 560℃ for 300 min, with an ammonia flow rate of 14 m³ / h. 3 / h, air cooling, to obtain wear-resistant gears.

[0059] Example 12

[0060] The only difference between this embodiment and Embodiment 11 is that the ammonia flow rate during the first nitriding treatment is 12m³. 3 / h, the ammonia gas flow rate for the second nitriding treatment is 18m³ / h. 3 The ammonia flow rate for the third nitriding treatment is 15 m³ / h. 3 / h.

[0061] Example 13

[0062] The only difference between this embodiment and Embodiment 11 is that the ammonia flow rate during the first nitriding treatment is 14m³. 3 / h, the ammonia gas flow rate for the second nitriding treatment is 20m³ / h. 3 The ammonia flow rate for the third nitriding treatment is 17 m³ / h. 3 / h.

[0063] Example 14

[0064] The only difference between this embodiment and Embodiment 11 is that the ammonia flow rate during the first nitriding treatment is 15m³. 3 The ammonia flow rate for the second nitriding treatment is 22 m³ / h.3 The ammonia flow rate for the third nitriding treatment is 18 m³ / h. 3 / h.

[0065] Comparative Example 1

[0066] The only difference between this comparative example and Example 1 is that the heating rate of the first low-temperature tempering treatment is 20°C / s, and the heating rate of the second low-temperature tempering treatment is 25°C / s.

[0067] Comparative Example 2

[0068] The only difference between this comparative example and Example 1 is that the heating rate of the first low-temperature tempering treatment is 35°C / s, and the heating rate of the second low-temperature tempering treatment is 45°C / s.

[0069] The wear-resistant gears obtained in Examples 1-14 and Comparative Examples 1-2 were tested according to the following method:

[0070] 1. Wear rate: The gear samples were tested for friction and wear using a MFT-R4000 high-speed reciprocating friction and wear tester. The test load was 30 N, the test time was 5 min, and the friction length was 5 × 10 mm. -3 The friction ball is made of Al2O3 material with a diameter of 4mm. The wear volume of the material after friction and wear is measured using a three-dimensional morphology instrument to obtain the wear rate. The formula for calculating the wear rate W is as follows: W=m / N·L, where W is the wear rate (g / N·m), m is the wear mass (g), N is the load (N), and L is the total stroke (m).

[0071] 2. Hardness: The test method is specified in GB / T 4340.1-2024 "Metallic materials - Vickers hardness test - Part 1: Test method", where the indenter is a regular square pyramidal diamond with a square base, and the test pressure is 98.07 N.

[0072] The test results are shown in Table 1 below:

[0073] Table 1 Performance test results of wear-resistant gears obtained in Examples 1-14 and Comparative Examples 1-2

[0074]

[0075] 1. Compared with Comparative Examples 1 and 2, the wear rate of gears obtained in Examples 1 to 14 is lower than that in Comparative Examples 1 and 2. This indicates that by controlling the heating rate of the first low-temperature tempering treatment to 25 to 30°C / s and limiting the heating rate of the second tempering temperature to 35 to 40°C / s, the gears obtained have better wear resistance.

[0076] 2. Comparing Examples 6 and 8-14, the gears obtained in Examples 12-13 showed extremely low wear rates and higher hardness, indicating that a three-stage nitriding treatment was used, and the ammonia gas flow rate during the first nitriding treatment was controlled to be 12-14 mg / L. 3 The ammonia flow rate during the secondary nitriding treatment is 18~20 m³ / h. 3 The ammonia flow rate at the temperature of the three nitriding treatments is 15~17 m³ / h. 3 / h can further improve the wear resistance and hardness of gears.

[0077] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A heat treatment process for wear-resistant gears, characterized in that, Includes the following steps: The gear is preheated, normalized, quenched, and then subjected to low-temperature tempering to obtain a wear-resistant gear. The low-temperature tempering includes a first low-temperature tempering treatment and a second low-temperature tempering treatment. The first low-temperature tempering treatment involves heating the temperature to 170-190°C at a heating rate of 25-30°C / s, holding it at that temperature for 50-65 minutes, and then air cooling. The second low-temperature tempering process involves heating the temperature to 160-170°C at a heating rate of 35-40°C / s, holding it at that temperature for 30-45 minutes, and then air cooling. The wear-resistant gear is composed of the following components by weight percentage: C 0.45%~0.75%, Si 0.05%~0.35%, Mn 0.55%~0.85%, Cr 1.6%~1.8%, Ni 1.2%~1.5%, P 0.004%~0.018%, S 0.006%~0.022%, Mo 0.22%~0.35%, Al 0.03%~0.05%, Cu 0.04%~0.23%, Nb 0.15%~0.20%, Ti 0.002%~0.006%, Sb 0.001%~0.004%, N 0.003%~0.013%, V 0.01%~0.03%, with the remainder being Fe and other unavoidable impurities.

2. The heat treatment process for wear-resistant gears according to claim 1, characterized in that, The preheating temperature is 350~400℃, and the holding time is 30~35min.

3. The heat treatment process for wear-resistant gears according to claim 1, characterized in that, The normalizing temperature is 1050~1150℃, and the holding time is 35~65min.

4. The heat treatment process for wear-resistant gears according to claim 1, characterized in that, The quenching temperature is 900~1000℃, and the holding time is 35~65min.

5. The heat treatment process for wear-resistant gears according to claim 1, characterized in that, The low-temperature tempering treatment is followed by nitriding treatment; The nitriding treatment is performed at a temperature of 460~580℃ for a time of 2220~3480 min.

6. The heat treatment process for wear-resistant gears according to claim 5, characterized in that, The nitriding treatment includes primary nitriding, secondary nitriding, and tertiary nitriding.

7. The heat treatment process for wear-resistant gears according to claim 5, characterized in that, The nitriding treatment is gas nitriding; The gas used in the nitriding process includes ammonia.

8. The heat treatment process for wear-resistant gears according to claim 7, characterized in that, The ammonia gas flow rate is 12~20m³. 3 / h.

9. The heat treatment process for wear-resistant gears according to claim 6, characterized in that, The nitriding treatment is performed at a temperature of 460-500℃ for 600-900 minutes, with an ammonia gas flow rate of 12-14 m³ / min. 3 / h; The secondary nitriding treatment is performed at a temperature of 510~550℃ for 1440~2160 min, with an ammonia gas flow rate of 18~20 m³ / min. 3 / h; The three nitriding treatments were performed at a temperature of 555-580℃ for 180-420 minutes, with an ammonia gas flow rate of 15-17 m³ / min. 3 / h.

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