Heat treatment process of wear-resistant gear

Abstract

The invention relates to the technical field of metal heat treatment, and provides a heat treatment process of a wear-resistant gear, which comprises the following steps: preheating a gear, normalizing, quenching, and tempering at low temperature to obtain the wear-resistant gear; low-temperature tempering comprises first-time low-temperature tempering treatment and second-time low-temperature tempering treatment; in the first low-temperature tempering treatment, the temperature is increased to 170-190 DEG C at the heating rate of 25-30 DEG C / s, heat preservation is conducted for 50-65 min, and air cooling is conducted; and in the second-time low-temperature tempering treatment, the temperature is increased to 160-170 DEG C at the heating rate of 35-40 DEG C / s, heat preservation is conducted for 30-45 min, and air cooling is conducted. By means of the technical scheme, the problem that in the prior art, a gear is poor in abrasion resistance is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal heat treatment, in particular to a heat treatment process of wear-resistant gear. BACKGROUND

[0002] Gear is the core transmission component of various equipment and mechanical systems, and its power transmission function is realized based on the friction force when the tooth profile meshes. When two gears mesh with each other, the friction force generated by the tooth surface contact can efficiently transmit the power of the driving shaft to the driven shaft. At the same time, according to the configuration and meshing mode of the gear, motion conversion in different directions and speeds can be realized, which is the basic element for realizing power and motion conversion in mechanical systems. The wear resistance of the gear directly determines the overall service life and running stability of the equipment. In the long-term transmission process, the tooth surface continuously bears friction, extrusion and impact load. The gear in the prior art has the problem of insufficient wear resistance. Insufficient wear resistance will cause the tooth surface to gradually wear and the precision to decrease, thereby causing the strength of the tooth surface to sharply decrease. When the wear accumulates to a certain extent, serious faults such as tooth breakage and tooth surface peeling are easily induced, which not only causes irreversible damage to the gear itself, but also can cause the entire transmission system to malfunction, and even cause the equipment to stop and production to be interrupted, etc. Therefore, a wear-resistant gear is needed to ensure the long-term reliable operation of the mechanical system and reduce the risk of failure and operation and maintenance cost. SUMMARY

[0003] The present application provides a heat treatment process of wear-resistant gear, which solves the problem of poor gear wear resistance in the related art.

[0004] The technical scheme of the present application is as follows: The present application provides a heat treatment process of wear-resistant gear, which includes the following steps: The gear is preheated, normalized, quenched and low-temperature tempered to obtain a wear-resistant gear. The low-temperature tempering includes first low-temperature tempering and second low-temperature tempering. The first low-temperature tempering is heated at a rate of 25-30℃ / s to 170-190℃, and the temperature is maintained for 50-65min and air-cooled. The second low-temperature tempering is heated at a rate of 35-40℃ / s to 160-170℃, and the temperature is maintained for 30-45min and air-cooled.

[0005] In the heat treatment process of the wear-resistant gear, two low-temperature tempering processes are adopted to accurately control the microstructure of the gear, so that the gear exhibits excellent performance and improves the service life of the gear.

[0006] As a further technical scheme, the preheating temperature is 350-400℃, and the holding time is 30-35min.

[0007] As a further technical solution, the temperature of the normalizing is 1050-1150 DEG C, and the holding time is 35-65 min.

[0008] As a further technical solution, the temperature of the quenching is 900-1000 DEG C, and the holding time is 35-65 min.

[0009] As a further technical solution, after the low-temperature tempering, the method further comprises a nitriding treatment.

[0010] As a further technical solution, the temperature of the nitriding treatment is 460-580 DEG C, and the time is 2220-3480 min.

[0011] As a further technical solution, the nitriding treatment comprises a first nitriding treatment, a second nitriding treatment and a third nitriding treatment.

[0012] As a further technical solution, the nitriding treatment is gas nitriding.

[0013] In the heat treatment process of the wear-resistant gear, the gas nitriding is adopted in the nitriding, and the gas nitriding can significantly improve the comprehensive performance of the gear, ensure the stable operation of the gear under various harsh conditions, and improve the overall performance and reliability of the equipment.

[0014] As a further technical solution, the gas in the gas nitriding comprises ammonia.

[0015] As a further technical solution, the amount of the ammonia is 12-20 m 3 / h.

[0016] As a further technical solution, the temperature of the first nitriding treatment is 460-500 DEG C, the time is 600-900 min, and the amount of the ammonia is 12-14 m 3 / h.

[0017] As a further technical solution, the temperature of the second nitriding treatment is 510-550 DEG C, the time is 1440-2160 min, and the amount of the ammonia is 18-20 m 3 / h.

[0018] As a further technical solution, the temperature of the third nitriding treatment is 555-580 DEG C, the time is 180-420 min, and the amount of the ammonia is 15-17 m 3 / h.

[0019] In the heat treatment process of the wear-resistant gear, the three-time nitriding process is adopted in the nitriding, and the amount of the ammonia in the first nitriding treatment is controlled to be 12-14 m 3 / h, the ammonia gas input amount of the second nitriding treatment is 18~20m 3 / h, the ammonia gas input amount of the third nitriding treatment is 15~17m 3 / h, by controlling the nitrogen gas input amount of each stage, the nitriding layer can be finely controlled, the consistency and stability of the gear quality can be improved, and the wear resistance and hardness of the gear can be further improved.

[0020] As a further technical solution, the wear-resistant gear is composed of the following weight percentage components: 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%, and the rest is Fe and other unavoidable impurities.

[0021] The working principle and beneficial effects of the present application are as follows: In the present application, the heating rate of the two low-temperature tempering in the heat treatment process of the gear is controlled, the heating rate of the first low-temperature tempering treatment is 25~30℃ / s, and the heating rate of the second low-temperature tempering treatment is 35~40℃ / s, which significantly improves the wear resistance of the gear; the heating rate of the first low-temperature tempering is 25~30℃ / s to ensure the stability of the material structure, and the heating rate of the second low-temperature tempering is accelerated to 35~40℃ / s to further optimize the structure, thereby improving the wear resistance of the gear and prolonging the service life of the gear. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor also fall within the scope of protection of the present application.

[0023] Embodiment 1 A heat treatment process for a wear-resistant gear, comprising the following steps: placing the gear in a heating device, first heating to 350℃ for preheating, and the holding time is 35min; after the preheating is completed, continue to heat to 1050℃ for normalizing, and the holding time is 65min, and then air cooling; The gear after the normalizing treatment is quenched, heated to 1000℃ during quenching, the holding time is 35min, and oil cooled to room temperature; After quenching, the gear is twice low-temperature tempered, the first low-temperature tempering is heated to 170℃ at a heating rate of 25℃ / s, holding for 65min, and air cooled; then the second low-temperature tempering is heated to 160℃ at a heating rate of 35℃ / s, holding for 45min, and air cooled, to obtain the wear-resistant gear.

[0024] Example 2 A heat treatment process of a wear-resistant gear, comprising the following steps: placing the gear in a heating device, first heating to 400℃ for preheating, the holding time is 30min; after preheating, continue to heat to 1150℃ for normalizing, the holding time is 35min, and then air cooling; The gear after the normalizing treatment is quenched, heated to 900℃ during quenching, the holding time is 65min, and oil cooled to room temperature; After quenching, the gear is twice low-temperature tempered, the first low-temperature tempering is heated to 190℃ at a heating rate of 30℃ / s, holding for 50min, and air cooled; then the second low-temperature tempering is heated to 170℃ at a heating rate of 40℃ / s, holding for 30min, and air cooled, to obtain the pretreated gear; The pretreated gear is placed in a nitriding device, ammonia gas is introduced (the introduction amount is 20m 3 / h) at 460℃, the nitriding treatment time is 3480min, and air cooling after treatment to obtain the wear-resistant gear.

[0025] Example 3 A heat treatment process of a wear-resistant gear, comprising the following steps: placing the gear in a heating device, first heating to 380℃ for preheating, the holding time is 33min; after preheating, continue to heat to 1100℃ for normalizing, the holding time is 45min, and then air cooling; The gear after the normalizing treatment is quenched, heated to 950℃ during quenching, the holding time is 50min, and oil cooled to room temperature; After quenching, the gear is twice low-temperature tempered, the first low-temperature tempering is heated to 180℃ at a heating rate of 28℃ / s, holding for 55min, and air cooled; then the second low-temperature tempering is heated to 165℃ at a heating rate of 37℃ / s, holding for 35min, and air cooled, to obtain the pretreated gear; The pretreated gear is placed in a nitriding device, ammonia gas is introduced (the introduction amount is 20m 3 / h) at 460℃, the nitriding treatment time is 3480min, and air cooling after treatment to obtain the wear-resistant gear.

[0026] Example 4 The difference between this example and Example 3 is that the heating rate of the first low-temperature tempering treatment is 30°C / s.

[0027] Example 5 The difference between this example and Example 3 is that the heating rate of the first low-temperature tempering treatment is 25°C / s.

[0028] Example 6 The difference between this example and Example 3 is that the heating rate of the second low-temperature tempering is 40°C / s.

[0029] Example 7 The difference between this example and Example 3 is that the heating rate of the second low-temperature tempering is 35°C / s.

[0030] Example 8 The difference between this example and Example 6 is that the process parameters of the nitriding treatment are different: the pretreated gear is placed in a nitriding device, ammonia gas is introduced at a temperature of 580°C (the amount of ammonia gas introduced is 12m 3 / h), the nitriding treatment time is 2220 min, and after the treatment is completed, air cooling is performed to obtain a wear-resistant gear.

[0031] Example 9 The difference between this example and Example 6 is that three nitriding treatments are used: the pretreated gear is placed in a nitriding device, the first nitriding treatment is performed at a temperature of 460°C for 900 min, and the amount of ammonia gas introduced is 10m 3 / h; the second nitriding treatment is performed at a temperature of 510°C for 2160 min, and the amount of ammonia gas introduced is 12m 3 / h; the third nitriding treatment is performed at a temperature of 555°C for 420 min, and the amount of ammonia gas introduced is 18m 3 / h, and air cooling is performed to obtain a wear-resistant gear.

[0032] Example 10 The difference between this example and Example 6 is that three nitriding treatments are used: the pretreated gear is placed in a nitriding device, the first nitriding treatment is performed at a temperature of 500°C for 600 min, and the amount of ammonia gas introduced is 10m 3 / h; the second nitriding treatment is performed at a temperature of 550°C for 1440 min, and the amount of ammonia gas introduced is 12m 3 / h; the third nitriding treatment is performed at a temperature of 580°C for 180 min, and the amount of ammonia gas introduced is 18m 3 / h, and air cooling is performed to obtain a wear-resistant gear.

[0033] Example 11 The difference between this example and Example 6 is only that three nitriding treatments are adopted: the pretreated gear is placed in a nitriding device, the first nitriding treatment is carried out at a temperature of 480°C for 700 min, and the ammonia gas is introduced at a rate of 10 m 3 / h; the second nitriding treatment is carried out at a temperature of 520°C for 1900 min, and the ammonia gas is introduced at a rate of 17 m 3 / h; the third nitriding treatment is carried out at a temperature of 560°C for 300 min, and the ammonia gas is introduced at a rate of 14 m 3 / h, and air cooling is carried out to obtain the wear-resistant gear.

[0034] Example 12 The difference between this example and Example 11 is only that the ammonia gas is introduced at a rate of 12 m 3 / h in the first nitriding treatment, the ammonia gas is introduced at a rate of 18 m 3 / h in the second nitriding treatment, and the ammonia gas is introduced at a rate of 15 m 3 / h in the third nitriding treatment.

[0035] Example 13 The difference between this example and Example 11 is only that the ammonia gas is introduced at a rate of 14 m 3 / h in the first nitriding treatment, the ammonia gas is introduced at a rate of 20 m 3 / h in the second nitriding treatment, and the ammonia gas is introduced at a rate of 17 m 3 / h in the third nitriding treatment.

[0036] Example 14 The difference between this example and Example 11 is only that the ammonia gas is introduced at a rate of 15 m 3 / h in the first nitriding treatment, the ammonia gas is introduced at a rate of 22 m 3 / h in the second nitriding treatment, and the ammonia gas is introduced at a rate of 18 m 3 / h in the third nitriding treatment.

[0037] Comparative Example 1 The difference between this comparative example and Example 1 is only 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.

[0038] Comparative Example 2 The difference between this comparative example and Example 1 is only 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.

[0039] The wear-resistant gears prepared in Examples 1-14 and Comparative Examples 1-2 are tested according to the following method: 1. Wear rate: The prepared gear samples were tested for friction and wear using a high-speed reciprocating friction and wear tester model MFT-R4000, the test load was 30 N, the test time was 5 min, the friction length was 5*10 -3 3m, the friction ball was Al2O3 material with a diameter of 4 mm, and the three-dimensional topography instrument was used to measure the wear volume of the material after friction and wear to obtain the wear rate; the calculation formula of the wear rate W is as follows: W = m / N*L, wherein 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); 2. Hardness: According to the test method specified in GB / T 4340.1-2024 "Metallic Materials Vickers Hardness Test Part 1: Test Method", wherein the indenter is a square-based pyramidal diamond, the test pressure is 98.07 N; The test results are shown in Table 1 below: Table 1 Performance test results of the wear-resistant gears prepared from Examples 1-14 and Comparative Examples 1-2

[0040] 1. Compared with Comparative Examples 1-2, the wear rate of the gears prepared from Examples 1-14 is lower, which indicates that the heating rate of the first low-temperature tempering process is controlled to be 25-30℃ / s, the heating rate of the second tempering temperature is limited to 35-40℃ / s, and the wear resistance of the prepared gears is better.

[0041] 2. Compared with Example 6 and Examples 8-14, the wear rate of the gears prepared from Examples 12-13 is extremely low, and the hardness is higher, which indicates that three nitriding processes are adopted, and the ammonia inlet amount of the first nitriding process is controlled to be 12-14 m 3 / h, the ammonia inlet amount of the second nitriding process is 18-20 m 3 / h, and the ammonia inlet amount of the third nitriding process is 15-17 m 3 / h, which can further improve the wear resistance and hardness of the gears.

[0042] The above is only a preferred embodiment of the present application, and is not intended to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

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 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.

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.

10. The heat treatment process for wear-resistant gears according to claim 1, characterized in that, 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.

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