Novel quenching process of 60CrMnMo material roller shaft

Abstract

The invention discloses a novel quenching process of a 60CrMnMo material roller shaft, and relates to the field of quenching and tempering heat treatment of a 60CrMnMo mechanical forge piece, and the novel quenching process adopts an inorganic quenching medium polyalkylene glycol, PAG for short; the novel quenching process comprises the following steps: a preliminary temperature rise stage: heating a workpiece in a furnace, raising the temperature of the workpiece to 650 DEG C, and keeping the temperature; in the rapid heating stage, the workpiece is heated, the temperature of the workpiece is increased to 860 DEG C, and heat preservation is conducted; in the cooling stage, the temperature of the workpiece is reduced to 840 DEG C and kept; in the quenching stage, the workpiece is discharged for quenching; in the cooling stage, after quenching is completed, the workpiece is cooled to the room temperature; flaw detection; in the tempering stage, the workpiece is heated to 420 DEG C for the first time and subjected to heat preservation for the first time, and after the heat preservation time is over, the workpiece is heated to 590 DEG C for the second time and subjected to heat preservation for the second time; and discharging the workpiece and naturally air-cooling to room temperature.

Description

Technical Field

[0001] The invention relates to the field of quenching and tempering heat treatment of mechanical forgings made of 60CrMnMo material, and specifically discloses a new quenching process for a roller shaft made of 60CrMnMo material. Background Art

[0002] Workpieces made of 60CrMnMo have good hardenability. During the quenching process of the industry's heat treatment process, in order to prevent quenching cracking, the quenching medium is usually an oil quenching medium; however, the oil quenching medium itself has major safety hazards. The oil medium is very likely to produce harmful gases such as oil smoke during the quenching process. The main harmful substances in the oil smoke include CO, CO2, SO2, ethylene, propylene, 1-butene and methane. At the same time, benzopyrene is also present in the oil smoke. This substance is a highly active indirect carcinogen, which poses a huge safety hazard, seriously pollutes the working environment, and harms the health of workers.

[0003] At present, polyalkylene glycol (PAG) is a widely recognized pollution-free quenching medium with outstanding environmental protection characteristics. It can significantly reduce the emission of wastewater, waste gas and solid waste in the production process, thereby effectively reducing the burden on the natural environment. Compared with traditional quenching oil media, PAG media are not easy to produce harmful gases such as oil smoke during use, and have minimal health hazards to operators. At the same time, it also avoids the problem of soil and water pollution caused by leakage of oil media. In addition, PAG media also have good stability and reusability, which further enhances its environmentally friendly characteristics.

[0004] The core purpose of the present invention is to promote and apply an innovative heat treatment process, which uses an inorganic quenching medium - polyalkylene glycol (PAG for short) as the core element, and cleverly combines the cooling technology of blast spray to completely replace the traditional quenching oil. This alternative is not only based on technical advancement and practical considerations, but also deeply reflects a high sense of responsibility for environmental protection and safe production. Summary of the invention

[0005] In view of the problem that the oil medium in the current quenching process of the roller made of 60CrMnMo material easily generates harmful gases such as oil smoke, the present invention provides a new quenching process for the roller made of 60CrMnMo material.

[0006] To solve the above problems, the present invention provides the following technical solutions:

[0007] A new quenching process for a 60CrMnMo material roller shaft, the new quenching process adopts an inorganic quenching medium polyalkylene glycol, referred to as PAG; the new quenching process comprises the following steps:

[0008] S1, initial heating stage, the workpiece is placed in the furnace for heating, so that the temperature of the workpiece is raised to 650℃ and kept warm;

[0009] S2, rapid heating stage, heating the workpiece to raise the temperature of the workpiece to 860°C and keep it warm;

[0010] S3, cooling stage, the workpiece temperature is reduced to 840℃ and kept warm;

[0011] S4, quenching stage, the workpiece is taken out of the furnace for quenching;

[0012] S5, cooling stage, after quenching is completed, the workpiece is cooled to room temperature;

[0013] S6, flaw detection;

[0014] S7, tempering stage, the workpiece is heated to 420℃ for the first time and kept warm for the first time. After the holding time is over, the workpiece is heated to 590℃ for the second time and kept warm for the second time;

[0015] S8. The workpiece is taken out of the furnace and naturally cooled to room temperature.

[0016] Preferably, in step S1, the temperature inside the furnace where the workpiece is loaded does not exceed 250°C, the heating rate does not exceed 50°C / h, and the insulation time is 4h, so as to ensure uniform heating of the workpiece, reduce the temperature difference between the inside and outside of the workpiece, and reduce the stress caused by the temperature gradient.

[0017] Preferably, in step S2, the heating rate is 80°C / h and the holding time is 18h, so that the workpiece completes the austenitization transformation.

[0018] Preferably, in step S3, the cooling rate is 1°C / min and the holding time is 4h.

[0019] Preferably, in step S4, a pre-cooling 5′PAG20′ quenching process is used to rapidly cool the high-temperature austenite to below the martensite transformation point to obtain a high-hardness martensite structure, wherein the PAG quenching time is calculated based on the effective cross-sectional size of the workpiece to ensure the consistency and uniformity of the quenching effect.

[0020] Preferably, in step S5, the cooling method adopts PAG cooling, and the workpiece is cooled by air blast spraying.

[0021] Preferably, when the workpiece is subjected to blast spray cooling, in order to ensure uniformity of cooling, the workpiece axis is rotated 180° every 30 minutes.

[0022] Preferably, in step S6, the workpiece is cooled to room temperature by means of air blast spraying and then subjected to flaw detection.

[0023] Preferably, in step S7, the first insulation time is 4 hours, and the second insulation time is 30 hours.

[0024] Preferably, in steps S4, S5, S7 and S8, the workpiece is subjected to flaw detection to check whether there are internal defects or cracks.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention adopts polyalkylene glycol (PAG) as a new type of quenching medium, so that the PAG quenching medium will not generate oil smoke and oil mist during use, thereby avoiding the safety hazards and environmental pollution caused by traditional oil cooling. This is of great significance for improving the quality of the working environment, protecting the health of workers, and meeting the increasingly stringent environmental protection regulations. Secondly, PAG has a price advantage over oil cooling medium. PAG has a long service life, low replacement frequency, and does not require additional environmental protection treatment costs. Therefore, its use cost is much lower than that of oil cooling medium, which greatly reduces the production cost.

[0027] 2. The present invention performs blast spray cooling by rotating the workpiece shaft by 180° every 30 minutes, thereby ensuring the uniformity of cooling and ensuring that the amount of water in the blast spray can evenly and efficiently cover the surface of the workpiece, thereby achieving a rapid and uniform cooling effect. This cooling method can not only accurately control the quenching hardness distribution of the workpiece, but also effectively reduce the risk of deformation and cracking of the workpiece, thereby improving the yield rate and overall quality of the product;

[0028] 3. The present invention adopts a cooling method that combines polyalkylene glycol (PAG) with blast spray, which reduces the occurrence of safety risks such as fire and explosion from the source. Compared with traditional quenching oil, PAG medium has a higher flash point and lower flammability, and can maintain high safety even under extreme conditions. In addition, the application of the blast spray system further enhances the controllability and stability of the cooling process, providing a strong guarantee for the safety management of the production site, and therefore has a very broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic diagram of a new quenching process flow of a 60CrMnMo material roller shaft of the present invention;

[0031] Figure 2 It is a schematic diagram of a temperature curve of a specific embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in this specific embodiment. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent.

[0033] This specific embodiment provides a new quenching process for a 60CrMnMo material roller shaft, such as Figure 1-Figure 2 shown.

[0034] At present, the following two processes are mainly used for 60CrMnMo rollers.

[0035] Process 1 includes the following steps:

[0036] S1. In the initial heating stage, the workpiece is loaded into the furnace when the furnace temperature does not exceed 250℃ and heated in the furnace. This heating process requires the workpiece to be heated slowly at a speed not exceeding 50℃ / h to ensure that the workpiece is heated evenly and slowly. This heating method helps to reduce the temperature difference between the inside and outside of the workpiece, thereby reducing the stress caused by the temperature gradient; as the temperature gradually increases, the workpiece gradually reaches a holding temperature of 650℃ and is kept at this temperature for 4h; this holding stage stabilizes the internal temperature of the workpiece, further ensuring the uniformity of heating.

[0037] S2, rapid heating stage, after completing the 4h insulation in step S1, the process enters the rapid heating stage, at this time, the heating rate is increased to 80℃ / h, the workpiece is quickly heated to 860℃, at this temperature, the workpiece will be kept warm for up to 18h to complete the austenitization transformation; austenite is a metal structure with excellent plasticity and toughness, which is crucial to improving the mechanical properties and processing properties of the workpiece.

[0038] S3, cooling stage, after completing the austenitizing transformation in step S2, the process enters the cooling stage, the cooling rate is precisely controlled at 1°C / min, and the workpiece is slowly cooled to 840°C. At this temperature, the workpiece is kept warm for another 4 hours to further stabilize its internal structure and performance.

[0039] S5, cooling stage, after completing the 4h insulation in step S3, the workpiece is taken out of the furnace for blast spray cooling; in order to ensure the uniformity of the spray, the workpiece shaft is rotated 180° every 30 minutes to ensure that all parts of the shaft can be evenly cooled; the spraying process continues until the shaft temperature drops to 280°C.

[0040] S7, tempering stage, after the workpiece shaft temperature in step S5 is reduced to 300°C, the workpiece is returned to the furnace and enters the tempering stage; during the tempering process, first, the workpiece is heated to 420°C and kept warm for 4 hours for the first time. The purpose of this step is to further reduce the temperature difference between the inside and outside of the workpiece and make the structure of the workpiece more uniform and stable; then, the workpiece is heated for a second time to 590°C and kept warm for a second time for 30 hours. At this temperature, the residual stress inside the workpiece is released, and its hardness and strength are also properly adjusted.

[0041] S8. After the second heat preservation for 30 hours in step S7, the workpiece is taken out of the furnace and naturally cooled to room temperature.

[0042] Process 2 includes the following steps:

[0043] S1. In the initial heating stage, the workpiece is loaded into the furnace when the furnace temperature does not exceed 250℃ and heated in the furnace. This heating process requires the workpiece to be slowly heated to 650℃ at a rate not exceeding 50℃ / h and kept at this temperature for 4h. This slow and uniform heating process and insulation stage can ensure uniform temperature distribution inside the workpiece, effectively reduce the temperature difference between the inside and outside of the workpiece, and thus reduce the thermal stress caused by temperature changes, which is crucial to prevent deformation and cracking of the workpiece.

[0044] S2, rapid heating stage, after completing the 4h insulation in step S1, the process requires that the workpiece be quickly heated to 860℃ at a rate of 80℃ / h and be kept at this temperature for 18h; this high temperature insulation stage is to quickly complete the austenitization transformation, that is, to transform the ferrite and cementite in the workpiece into austenite, creating favorable conditions for the subsequent quenching process; austenite has good plasticity and toughness, which is conducive to the formation of fine martensitic structure during quenching, thereby improving the hardness and strength of the workpiece.

[0045] S3, cooling stage, after completing the 18h heat preservation in step S2, the process requires cooling the workpiece to 840°C at a cooling rate of 1°C / min and keeping it at that temperature for 4h.

[0046] S4, quenching stage, after completing the 4h insulation in step S3, the workpiece is taken out of the furnace for quenching; quenching is an extremely critical step in heat treatment, which rapidly cools the high-temperature austenite to below the martensite transformation point to obtain a high-hardness martensite structure; the pre-cooling 5′PAG20′ quenching process adopted here is the calculation of the PAG quenching time based on the effective cross-sectional size of the workpiece to ensure the consistency and uniformity of the quenching effect.

[0047] S5, cooling stage, after quenching, the workpiece needs to be cooled by blast spray, and the shaft of the workpiece is rotated 180° every 30 minutes during the blast spray process. This step helps to further evenly cool the workpiece and prevent deformation and cracking caused by local overheating or uneven cooling; when the shaft temperature of the workpiece cools to 300℃, the workpiece is returned to the furnace.

[0048] S7, tempering stage, tempering is to heat the quenched workpiece to a certain temperature and keep it warm for a period of time to eliminate quenching stress, stabilize the structure, and improve the plasticity and toughness of the workpiece; the workpiece after returning to the furnace is heated to 420°C and kept warm for the first time for 4 hours. After the warming time is over, the workpiece is heated to 590°C for the second time and kept warm for 30 hours; the tempering operation in step S7 can not only effectively reduce the residual stress inside the workpiece, but also optimize its comprehensive mechanical properties, so that the workpiece has good toughness and plasticity while meeting the hardness and strength requirements.

[0049] S8. The workpiece is taken out of the furnace and naturally cooled to room temperature.

[0050] The present invention provides a novel quenching process for a 60CrMnMo material roller shaft, comprising the following steps:

[0051] S1. In the initial heating stage, the workpiece is loaded into the furnace when the furnace temperature does not exceed 250℃ and heated in the furnace. This heating process requires the workpiece to be slowly heated to 650℃ at a rate not exceeding 50℃ / h and kept at this temperature for 4h. The slow heating in this stage ensures the uniformity of the temperature distribution inside the workpiece, effectively reduces the temperature difference between the inside and outside of the workpiece, and thus reduces the thermal stress caused by the temperature gradient, which is crucial to prevent the workpiece from deformation or cracking during the heat treatment process.

[0052] S2, rapid heating stage, after completing the 4h insulation in step S1, the process requires that the workpiece be rapidly heated to 860℃ at a rate of 80℃ / h and be kept at this temperature for 18h; this high temperature insulation stage is crucial for quickly completing the austenitization transformation; austenite is a solid solution of steel at high temperature, with good plasticity and toughness, and is the organizational state that must be achieved before quenching. By keeping at this temperature for a long time, it can be ensured that most of the internal organization of the workpiece is transformed into austenite, which is fully prepared for the subsequent quenching process.

[0053] S3, cooling stage, after completing the 18h heat preservation in step S2, the process requires cooling the workpiece to 840°C and keeping it for 4h.

[0054] S4, quenching stage, after completing the 4h insulation in step S3, the workpiece is taken out of the furnace for quenching; quenching is an extremely critical step in heat treatment, which rapidly cools the high-temperature austenite to below the martensite transformation point to obtain a high-hardness martensite structure; the pre-cooling 5′PAG20′ quenching process adopted here is the calculation of the PAG quenching time based on the effective cross-sectional size of the workpiece to ensure the consistency and uniformity of the quenching effect.

[0055] S5, cooling stage, after quenching is completed, the workpiece needs to be cooled to room temperature through blast spray. This process not only helps to further reduce the temperature of the workpiece, but also provides conditions for subsequent flaw detection.

[0056] S6. Flaw detection to check for internal defects or cracks is critical to ensuring the quality and reliability of the workpiece.

[0057] S7, tempering stage, after the flaw detection of step S6 is completed, the workpiece enters the tempering stage; tempering is to heat the quenched workpiece to a certain temperature and keep it warm for a period of time to eliminate quenching stress, stabilize the structure, and improve the plasticity and toughness of the workpiece; first, the workpiece after returning to the furnace is heated to 420°C for the first time and kept warm for the first time, and the holding time is 4 hours. The tempering at this stage helps to reduce the quenching stress while maintaining a certain hardness; after the first holding time is over, the workpiece is heated to 590°C for the second time and kept warm for the second time, and the holding time is 30 hours; this high temperature and long-term holding can further stabilize the structure, improve the plasticity and toughness of the workpiece, and maintain a certain strength.

[0058] S8. The workpiece is taken out of the furnace and naturally cooled to room temperature.

[0059] In summary, the new quenching process for a 60CrMnMo material roller provided by the present invention is compared with process one and process two. First, by using PAG cooling and blast spray in combination instead of oil cooling, all workpieces are subjected to flaw detection after being taken out of the furnace, and no defects are found; and according to the inspection requirements, samples are taken at the R / 3 wall thickness, and the workpiece strength reaches more than 1000MPa, and the room temperature impact is more than 80J, which is much higher than the oil cooling data.

[0060] Secondly, after the new quenching process for a 60CrMnMo roller provided by the present invention is implemented, the hardness of the workpiece is detected to be between 300-300HB, and both the value and uniformity meet the requirements.

[0061] Therefore, the new quenching process for a 60CrMnMo material roller provided by the present invention is compared with process one and process two. Process one and process two may produce oil smoke and oil mist during the oil cooling process, which not only poses a threat to the health of on-site workers, but also may cause environmental pollution, increasing safety hazards and environmental pressures in the production process; in addition, the cost of oil-cooling medium is relatively high, especially in the case of large-scale use and frequent replacement, which will bring a considerable economic burden to the enterprise; in contrast, PAG in the new quenching process for a 60CrMnMo material roller provided by the present invention as a new quenching medium has shown significant advantages.

[0062] First, the new quenching process for the 60CrMnMo roller provided by the present invention does not generate oil smoke and oil mist during the actual production process, thereby avoiding the safety hazards and environmental pollution caused by oil cooling. This is of great significance for improving the quality of the working environment, protecting the health of on-site workers, and meeting increasingly stringent environmental regulations. Secondly, PAG has a higher cost-effectiveness than oil cooling media, which can fully reduce production costs. In addition, since PAG has a long service life and low replacement frequency, it does not require additional environmental protection treatment costs, so its use cost is much lower than that of oil cooling media.

[0063] It can be seen that the new quenching process for the 60CrMnMo material roller provided by the present invention can meet the quenching requirements of workpieces of different materials, shapes and sizes, thereby ensuring the flexibility and versatility of the heat treatment process; further, the heat treatment plant can achieve efficient and stable heat treatment production without frequently changing the quenching medium, so it has a very broad application prospect.

[0064] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A new quenching process for a 60CrMnMo roller shaft, characterized in that: The novel quenching process uses an inorganic quenching medium, polyalkylene glycol, referred to as PAG; the novel quenching process comprises the following steps: S1, initial heating stage, the workpiece is placed in the furnace for heating, so that the temperature of the workpiece is raised to 650℃ and kept warm; S2, rapid heating stage, heating the workpiece to raise the temperature of the workpiece to 860°C and keep it warm; S3, cooling stage, the workpiece temperature is reduced to 840℃ and kept warm; S4, quenching stage, the workpiece is taken out of the furnace for quenching; S5, cooling stage, after quenching is completed, the workpiece is cooled to room temperature; S6, flaw detection; S7, tempering stage, the workpiece is heated to 420℃ for the first time and kept warm for the first time. After the holding time is over, the workpiece is heated to 590℃ for the second time and kept warm for the second time; S8. The workpiece is taken out of the furnace and naturally cooled to room temperature.

2. The novel quenching process for a 60CrMnMo roller shaft according to claim 1 is characterized in that: In step S1, the temperature of the workpiece in the furnace does not exceed 250°C, the heating rate does not exceed 50°C / h, and the insulation time is 4h to ensure uniform heating of the workpiece, reduce the temperature difference between the inside and outside of the workpiece, and reduce the stress caused by the temperature gradient.

3. The novel quenching process for a 60CrMnMo roller shaft according to claim 1 is characterized in that: In step S2, the heating rate is 80°C / h and the holding time is 18h, so that the workpiece completes the austenitization transformation.

4. The novel quenching process for a 60CrMnMo roller shaft according to claim 1 is characterized in that: In step S3, the cooling rate is 1°C / min and the holding time is 4h.

5. The novel quenching process for a 60CrMnMo roller according to claim 1 is characterized in that: In step S4, a pre-cooling 5′PAG20′ quenching process is used to rapidly cool the high-temperature austenite to below the martensite transformation point to obtain a high-hardness martensite structure, wherein the PAG quenching time is calculated based on the effective cross-sectional size of the workpiece to ensure the consistency and uniformity of the quenching effect.

6. The novel quenching process for a 60CrMnMo roller shaft according to claim 1 is characterized in that: In step S5, the cooling method adopts PAG cooling, and the workpiece is cooled by air blast spray.

7. The novel quenching process for a 60CrMnMo roller shaft according to claim 6 is characterized in that: When the workpiece is subjected to blast spray cooling, in order to ensure the uniformity of cooling, the workpiece axis is rotated 180° every 30 minutes.

8. The novel quenching process for a 60CrMnMo roller shaft according to claim 1 is characterized in that: In step S6, the workpiece is cooled to room temperature by means of air blast spraying and then subjected to flaw detection.

9. The novel quenching process for a 60CrMnMo roller shaft according to claim 1 is characterized in that: In step S7, the first insulation time is 4 hours, and the second insulation time is 30 hours.

10. The novel quenching process for a 60CrMnMo roller according to claim 1, characterized in that: In the steps S4, S5, S7 and S8, the workpiece is subjected to flaw detection to check whether there are internal defects or cracks.

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