Heat treatment process method for 20Cr13 blade steel forgings

Abstract

The invention provides a heat treatment process method of a 20Cr13 blade steel forging, and relates to the technical field of heat treatment processes of turbine blades, and the method comprises the following steps: uniformly putting 20Cr13 blades into a charging basket, putting the charging basket into a heating furnace, heating to a first preset temperature along with the furnace, and preserving heat for a first preset duration; transferring the charging basket into a closed air cooling chamber; carrying out air cooling on the 20Cr13 blade for the first time, carrying out auxiliary cooling on the 20Cr13 blade by spraying water mist, and then carrying out air cooling on the 20Cr13 blade for the second time; and the 20Cr13 blade is put into a charging basket, then the charging basket is put into a tempering furnace, the temperature is increased to a second preset temperature along with the furnace, heat preservation is conducted for a second preset duration, and the 20Cr13 blade is taken out of the furnace and air-cooled. According to the invention, the generation of oil smoke in the heat treatment process is effectively avoided, the pollution to the environment is obviously reduced, and the clean and environment-friendly level of production is improved.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for turbine blades, and particularly to a heat treatment process for 20Cr13 blade steel forgings. Background Technology

[0002] The tensile strength of 20Cr13 blade steel is 800-950 MPa, Rp0.2≥600 MPa, impact toughness≥20J, and FATT50≤25℃. However, the failure of FATT50 of 20Cr13 blade steel is a common problem encountered in the hot working process. Due to its complexity, it has always been a hot topic in turbine blade research. The chemical composition of 20Cr13 blade material is shown in Table 1.

[0003] Table 1 Chemical composition of 20Cr13 material Due to the high FATT50 requirements of 20Cr13 blade steel, oil cooling has been the preferred heat treatment method for quenching to ensure the stability of the mechanical properties of forgings. However, under the global dual carbon goals of "peak carbon and carbon neutrality" by 2050, the severe pollution from oil fumes emitted during quenching due to oil cooling necessitates exploring environmentally friendly heat treatment methods to replace oil cooling.

[0004] However, the existing heat treatment process for 20Cr13 blade steel forgings will cause the workpiece to catch fire and produce oil fumes when it enters the oil, and there will be a lot of oil on the surface when it exits the oil. When it enters the next process (tempering), it will produce a lot of dense smoke due to incomplete combustion, which not only pollutes the environment, but also poses a potential hazard to the health of workers, and does not meet environmental protection requirements. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a heat treatment process for 20Cr13 blade steel forgings, which can solve the technical problems of existing heat treatment processes for 20Cr13 blade steel forgings, such as the workpiece igniting and producing oil fumes when entering the oil, having a lot of oil on the surface when exiting the oil, and producing a lot of dense smoke due to incomplete combustion when entering the next process (tempering), which not only pollutes the environment but also poses a potential hazard to the health of workers and does not meet environmental protection requirements.

[0006] In a first aspect, the present invention provides a heat treatment process for 20Cr13 blade steel forgings, the method comprising: S1: Place the 20Cr13 blades evenly into the material basket, then place the material basket into the heating furnace, heat it up to the first preset temperature, and keep it at the temperature for the first preset time. S2: Transfer the material basket to a sealed, air-cooled room; S3: The 20Cr13 blades are subjected to a first air cooling, and then the 20Cr13 blades are assisted by spraying water mist for cooling. After that, the 20Cr13 blades are subjected to a second air cooling. S4: Place the 20Cr13 blades into the material basket, then place the material basket into the tempering furnace, heat it to the second preset temperature, keep it at the temperature for the second preset time, and then air cool it after it is taken out of the furnace.

[0007] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, by adopting a combination of furnace heating, segmented air cooling, and water mist-assisted cooling, the traditional oil cooling process is replaced, which effectively avoids the generation of oil fumes during heat treatment, significantly reduces environmental pollution, and improves the cleanliness and environmental protection level of production. At the same time, by reasonably controlling the temperature, holding time, and cooling rate at each stage, the internal stress of the forging can be effectively eliminated, quenching cracks and deformation can be prevented, the uniformity of the structure and mechanical properties can be improved, and the stability and service life of the blades under high stress and high temperature environments can be ensured. Attached Figure Description

[0008] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0009] Figure 1 This is a schematic flowchart of a heat treatment process for 20Cr13 blade steel forgings provided in an embodiment of the present invention. Detailed Implementation

[0010] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0011] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this invention.

[0012] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention.

[0013] Reference manual attached Figure 1 The diagram shows a structural schematic of a heat treatment process for a 20Cr13 blade steel forging provided in an embodiment of the present invention.

[0014] The present invention provides a heat treatment process for 20Cr13 blade steel forgings, comprising: S1: Place the 20Cr13 blades evenly into the material basket, then place the material basket into the heating furnace, heat it up to the first preset temperature, and keep it at the temperature for the first preset time.

[0015] It should be noted that by evenly placing the 20Cr13 blades in the material basket and heating them with the furnace, the abnormal structure and thermal stress concentration caused by local overheating or uneven heating can be effectively avoided, ensuring a stable and consistent heating process.

[0016] In one possible implementation, the first preset temperature ranges from 950 to 1050°C, and the first preset duration ranges from 1 to 3 hours.

[0017] S2: Transfer the material basket to a sealed, air-cooled room.

[0018] It should be noted that by quickly transferring the material basket to the sealed air-cooled chamber, the blades can be prevented from being exposed to high-temperature air for a long time, reducing oxidation and decarburization, while ensuring the continuity and controllability of the cooling process.

[0019] In one possible implementation, the transfer time of transferring the material basket to the sealed air-cooled chamber does not exceed 3 minutes.

[0020] S3: The 20Cr13 blades are first air-cooled, then the 20Cr13 blades are assisted by water mist spraying, and then the 20Cr13 blades are air-cooled a second time.

[0021] In this embodiment of the invention, the blade temperature is reduced by the first air cooling to avoid excessive thermal stress caused by rapid cooling. The cooling rate is further controlled by water mist spraying to ensure uniform temperature difference between the blade surface and interior, reducing the risk of cracks and deformation. Finally, a second air cooling is performed to ensure that the blade is completely cooled to the required temperature. This process effectively improves the uniformity of the blade's structure and mechanical properties, while avoiding oil fume pollution caused by oil cooling processes, thus meeting environmental protection requirements.

[0022] In one possible implementation, the duration of the first air cooling is 5 to 15 minutes, the duration of the water mist-assisted cooling is 10 to 20 minutes, and the duration of the second air cooling is 40 to 60 minutes.

[0023] In one possible implementation, the water mist flow rate for water spray-assisted cooling ranges from 0.4 to 0.6 mm. 3 / min.

[0024] In one possible implementation, auxiliary cooling cools the root surface of the 20Cr13 blade to 100 to 200°C, and then the 20Cr13 blade is air-cooled to below 80°C.

[0025] S4: Place the 20Cr13 blades into the material basket, then place the material basket into the tempering furnace, heat it to the second preset temperature, hold it for the second preset time, and then air cool it after it is taken out of the furnace.

[0026] It should be noted that the blades are heated along with the furnace and held at a second preset temperature, which can effectively release the residual stress generated during the quenching process, stabilize the microstructure, improve the dimensional accuracy and service reliability of the blades, and the air cooling after exiting the furnace also simplifies the process and reduces energy consumption.

[0027] In one possible implementation, the second preset temperature is 660°C, and the second preset duration ranges from 4 to 6 hours.

[0028] In one possible implementation, the first preset temperature is 950℃. The first preset duration is 3 hours. The transfer time for moving the material basket to the sealed air-cooled chamber is 2 minutes. The duration of the first air cooling is 5 minutes, the duration of the water mist-assisted cooling is 10 minutes, and the duration of the second air cooling is 40 minutes. The water mist flow rate for the water mist-assisted cooling is 0.4 mm. 3 / min. Auxiliary cooling cools the root surface of the 20Cr13 blade to 100°C, then the 20Cr13 blade is air-cooled to below 80°C. The second preset temperature is 660°C, and the second preset duration is 4 hours.

[0029] In one possible implementation, the first preset temperature is 1000℃. The first preset duration is 2 hours. The transfer time for moving the material basket to the sealed air-cooled chamber is 2.5 minutes. The duration of the first air cooling is 10 minutes, the duration of the water mist-assisted cooling is 15 minutes, and the duration of the second air cooling is 50 minutes. The water mist flow rate for the water mist-assisted cooling is 0.5 mm. 3 / min. Auxiliary cooling cools the root surface of the 20Cr13 blade to 150℃, and then the 20Cr13 blade is air-cooled to below 80℃. The second preset temperature is 660℃, and the second preset duration is 5 hours.

[0030] In one possible implementation, the first preset temperature is 1050℃. The first preset duration is 1 hour. The transfer time for moving the material basket to the sealed air-cooled chamber is 3 minutes. The duration of the first air cooling is 15 minutes, the duration of the water mist-assisted cooling is 20 minutes, and the duration of the second air cooling is 60 minutes. The water mist flow rate for the water mist-assisted cooling is 0.6 mm. 3 / min. Auxiliary cooling cools the root surface of the 20Cr13 blade to 200℃, followed by air cooling to below 80℃. The second preset temperature is 660℃, and the second preset duration is 6 hours.

[0031] Example 1: The heat treatment process requires that the blades be placed evenly in a standard material basket. (1) Heating and heat preservation: Place the material basket into the heating furnace and heat it to 950℃, then keep it at that temperature for 3 hours. (2) Transfer of material from furnace: Transfer the material frame to a sealed air-cooled chamber (transfer time 2 min). (3) Alternative cooling method: After the forging is removed from the furnace, it is transferred to a cooling quencher. First, it is air-cooled for 5 minutes, then water-mist air-cooled for 10 minutes, with water mist spraying to assist cooling. The water mist flow rate is 0.4 mm3 / min, and the surface temperature of the blade root of the forging is about 100℃. Then it is air-cooled for 40 minutes to cool to below 80℃.

[0032] (4) Tempering treatment: Place the blades evenly in a general tempering basket, then put the tempering basket into the tempering furnace and heat it to 660°C. Keep it at that temperature for 4 hours and then air cool it.

[0033] Example 2: The heat treatment process requires that the blades be placed evenly in a standard material basket. (1) Heating and heat preservation: Place the material basket into the heating furnace and heat it to 1000℃, then keep it at that temperature for 2 hours. (2) Transfer of material from furnace: Transfer the material frame to a sealed air-cooled chamber (transfer time 2.5 min). (3) Alternative oil cooling method: After the forging is removed from the furnace, it is transferred to a cooling quencher. First, it is air-cooled for 10 minutes, then water mist air-cooled for 15 minutes, water mist is sprayed to assist cooling, the water mist flow rate is 0.5 mm3 / min, the surface temperature of the blade root of the forging is about 150℃, and then air-cooled for 50 minutes to cool to below 80℃.

[0034] (4) Tempering treatment: Place the blades evenly in a general tempering basket, then put the tempering basket into the tempering furnace and heat it to 660°C. Keep it at that temperature for 5 hours and then air cool it after removing it from the furnace.

[0035] Example 3: The heat treatment process requires that the blades be placed evenly in a standard material basket. (1) Heating and heat preservation: Place the material basket into the heating furnace and heat it to 1050℃, then keep it at that temperature for 1 hour. (2) Transfer of material from furnace: Transfer the material frame to a sealed air-cooled chamber (transfer time 3 min). (3) Alternative cooling method: After the forging is removed from the furnace, it is transferred to a cooling quencher. First, it is air-cooled for 15 minutes, then water-mist air-cooled for 20 minutes, with water mist spraying to assist cooling. The water mist flow rate is 0.6 mm3 / min, and the surface temperature of the blade root of the forging is about 200℃. Then it is air-cooled for 60 minutes to cool to below 80℃.

[0036] (4) Tempering treatment: Place the blades evenly in a general tempering basket, then put the tempering basket into the tempering furnace and heat it to 660°C. Keep it at that temperature for 6 hours and then air cool it after removing it from the furnace.

[0037] Comparative Example 1: The solution heat treatment process requires that the blades be placed evenly in a general solution material basket, and then the solution material basket be placed in a solution furnace and heated to 950°C, held at that temperature for 3 hours, and then cooled with oil.

[0038] The tempering heat treatment process requires that the blades be evenly placed in a general tempering basket, and then the tempering basket be placed in the tempering furnace and heated to 660°C, held for 4 hours and then air-cooled.

[0039] Comparative Example 2: The solution heat treatment process requires that the blades be placed evenly in a general solution material basket, and then the solution material basket be placed in a solution furnace and heated to 1000℃, held at that temperature for 2 hours, and then cooled with oil.

[0040] The tempering heat treatment process requires that the blades be evenly placed in a general tempering basket, and then the tempering basket be placed in the tempering furnace and heated to 660°C, held for 5 hours and then air-cooled.

[0041] Comparative Example 3: The solution heat treatment process requires that the blades be placed evenly in a general solution material basket, and then the solution material basket be placed in a solution furnace and heated to 1050℃, held at that temperature for 3 hours and then cooled with oil.

[0042] The tempering heat treatment process requires that the blades be evenly placed in a general tempering basket, and then the tempering basket be placed in the tempering furnace and heated to 660°C, held for 6 hours and then air-cooled.

[0043] Specifically, the process parameters of the three examples and comparative examples of the present invention—quenching heating time, water mist cooling time, and tempering heating time—are mainly related to the effective thickness of the forging. Example 1 and Comparative Example 1 are applicable to forgings with an effective thickness L≤60mm, Example 2 and Comparative Example 2 are applicable to forgings with an effective thickness 60mm<L≤120mm, and Example 3 and Comparative Example 3 are applicable to forgings with an effective thickness 120mm<L≤180mm.

[0044] Forgings were obtained according to the ASTM A370 method using the heat treatment methods of the examples and comparative examples. Longitudinal samples were taken for room temperature tensile and room temperature impact tests. The test results are shown in Table 2 below. Table 2 shows a comparison of the mechanical properties of the three sets of examples and three sets of comparative examples under different heat treatment processes. The results show that the examples, while meeting the requirements for tensile strength (Rm 860–872 MPa), yield strength (Rp0.2 723–740 MPa), elongation (A% ≥18.5%), and reduction of area (Z% ≥64%), also possess good impact toughness (KV2J 61–82 J), balancing strength, toughness, and heat treatment stability, thus verifying the effectiveness and feasibility of replacing the oil-cooled heat treatment process.

[0045] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, by adopting a combination of furnace heating, segmented air cooling, and water mist-assisted cooling to replace the traditional oil cooling process, the generation of oil fumes during heat treatment is effectively avoided, significantly reducing environmental pollution and improving the cleanliness and environmental protection level of production. At the same time, by reasonably controlling the temperature, holding time, and cooling rate at each stage, the internal stress of the forging can be effectively eliminated, quenching cracks and deformation can be prevented, the uniformity of the structure and mechanical properties can be improved, and the stability and service life of the blades under high stress and high temperature environments can be ensured.

[0046] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the preferred embodiments, while those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A heat treatment process for 20Cr13 blade steel forgings, characterized in that, include: S1: Place the 20Cr13 blades evenly into the material basket, then place the material basket into the heating furnace, heat it up to the first preset temperature, and keep it at the temperature for the first preset time. S2: Transfer the material basket to a sealed, air-cooled room; S3: The 20Cr13 blades are subjected to a first air cooling, and then the 20Cr13 blades are assisted by spraying water mist for cooling. After that, the 20Cr13 blades are subjected to a second air cooling. S4: Place the 20Cr13 blades into the material basket, then place the material basket into the tempering furnace, heat it to the second preset temperature, keep it at the temperature for the second preset time, and then air cool it after it is taken out of the furnace.

2. The heat treatment process for 20Cr13 blade steel forgings according to claim 1, characterized in that, The first preset temperature ranges from 950 to 1050°C, and the first preset duration ranges from 1 to 3 hours.

3. The heat treatment process for the 20Cr13 blade steel forging according to claim 1, characterized in that, The transfer time of the material basket to the sealed air-cooled room shall not exceed 3 minutes.

4. The heat treatment process for the 20Cr13 blade steel forging according to claim 1, characterized in that, The duration of the first air cooling is 5 to 15 minutes, the duration of the water mist-assisted cooling is 10 to 20 minutes, and the duration of the second air cooling is 40 to 60 minutes.

5. The heat treatment process for 20Cr13 blade steel forgings according to claim 1, characterized in that, The water mist flow rate for water spray-assisted cooling ranges from 0.4 to 0.6 mm. 3 / min.

6. The heat treatment process for the 20Cr13 blade steel forging according to claim 1, characterized in that, Auxiliary cooling cools the root surface of the 20Cr13 blade to 100 to 200°C, and then the 20Cr13 blade is air-cooled to below 80°C.

7. The heat treatment process for 20Cr13 blade steel forgings according to claim 1, characterized in that, The second preset temperature is 660℃, and the second preset duration ranges from 4 to 6 hours.

8. The heat treatment process for 20Cr13 blade steel forgings according to claim 1, characterized in that, The first preset temperature is 950℃; the first preset duration is 3 hours; the transfer time for transferring the material basket to the sealed air-cooled chamber is 2 minutes; the duration of the first air cooling is 5 minutes, the cooling time for water mist-assisted cooling is 10 minutes, the duration of the second air cooling is 40 minutes; the water mist flow rate for water mist-assisted cooling is 0.4 mm. 3 / min; auxiliary cooling cools the root surface of the 20Cr13 blade to 100, and then air-cools the 20Cr13 blade to below 80°C; the second preset temperature is 660°C, and the second preset duration is 4 hours.

9. The heat treatment process for 20Cr13 blade steel forgings according to claim 1, characterized in that, The first preset temperature is 1000℃; the first preset duration is 2 hours; the transfer time for transferring the material basket to the sealed air-cooled chamber is 2.5 minutes; the duration of the first air cooling is 10 minutes, the cooling time for water mist-assisted cooling is 15 minutes, the duration of the second air cooling is 50 minutes; the water mist flow rate for water mist-assisted cooling is 0.5 mm. 3 / min; auxiliary cooling cools the root surface of the 20Cr13 blade to 150°C, and then air-cools the 20Cr13 blade to below 80°C; the second preset temperature is 660°C, and the second preset duration is 5 hours.

10. The heat treatment process for 20Cr13 blade steel forgings according to claim 1, characterized in that, The first preset temperature is 1050℃; the first preset duration is 1 hour; the transfer time for transferring the material basket to the sealed air-cooled chamber is 3 minutes; the duration of the first air cooling is 15 minutes, the cooling time for water mist-assisted cooling is 20 minutes, the duration of the second air cooling is 60 minutes; the water mist flow rate for water mist-assisted cooling is 0.6 mm. 3 / min; The auxiliary cooling cools the root surface of the 20Cr13 blade to 200°C, and then the 20Cr13 blade is air-cooled to below 80°C; the second preset temperature is 660°C, and the second preset duration is 6 hours.

Images