Powder metallurgy forming process for compressor flange

Abstract

The invention provides a powder metallurgy forming process of a compressor flange. The process comprises the working procedures of spray granulation, cold isostatic pressing forming, high-temperature sintering, hot isostatic pressing forming and steam treatment. The compressor flange produced through the method has high density, uniform structure and excellent mechanical property, similarly, special-shaped powder metallurgy parts with the high density requirement, powder metallurgy parts with the extra-high air tightness requirement and the like can be produced, the batch stability is good, and the efficiency is high.

Description

Technical Field

[0001] The invention relates to the field of powder metallurgy, and in particular to a powder metallurgy method for preparing a compressor flange through an isostatic pressing process. Background Art

[0002] Compressor flanges are important mechanical connection components in compressors, which require high strength, pressure resistance and good mechanical properties. Traditional compressor flanges are generally prepared by forging or casting processes, but these processes have problems such as low material utilization, insufficient molding accuracy, and complex subsequent processing. Powder metallurgy technology has gradually become an effective method for flange preparation because it can effectively improve material utilization, simplify processing procedures, and achieve high-precision molding of complex-shaped parts.

[0003] However, the existing powder metallurgy process often affects the mechanical properties and service life of the flange due to problems such as insufficient sintering density and uneven structure when preparing compressor flanges. In order to overcome these defects, it is of great significance to develop a powder metallurgy method for preparing high-performance compressor flanges using an isostatic pressing process. Summary of the invention

[0004] The purpose of the present invention is to provide a powder metallurgy method for preparing a compressor flange based on an isostatic pressing process, and a compressor flange with high density, high strength and uniform structure is obtained through a combined process of spray granulation, cold isostatic pressing, sintering and hot isostatic pressing, thereby significantly improving the mechanical properties and service life of the product.

[0005] The present invention adopts the following technical scheme.

[0006] A powder metallurgy forming process for a compressor flange comprises the following steps: metal powder is spray granulated and then subjected to cold isostatic pressing, sintering, hot isostatic pressing and steam treatment in sequence to obtain a compressor flange.

[0007] The present invention discloses a compressor flange prepared according to the powder metallurgy forming process of the above compressor flange. Although powder metallurgy has good advantages over forging, the biggest problem is that the performance of existing powder metallurgy flanges is much worse than that of forged products, and can only be downgraded for use or even cannot be used. The present invention improves the existing process for preparing powder flanges, first granulation is performed, and then cold isostatic pressing, sintering, hot isostatic pressing and steam treatment are performed in sequence to obtain a compressor flange, and the key performance is equivalent to that of a forged flange, especially the air tightness is consistent, which solves the problem of poor air tightness of existing powder metallurgy flanges and overcomes the technical prejudice of the prior art that powder metallurgy products are not as good as forged products in air tightness.

[0008] In the present invention, the metal powder is iron-based metal powder.

[0009] In the present invention, during spray granulation, the spray gas pressure is 0.5 to 1.5 MPa, and the granulation temperature is 50 to 200° C. The obtained particles are uniform and well-shaped, and have good fluidity.

[0010] In the present invention, after spray granulation, metal particles with a particle size of 10 to 100 microns are sequentially subjected to cold isostatic pressing, sintering, hot isostatic pressing and steam treatment to obtain a compressor flange.

[0011] In the present invention, during cold isostatic pressing, the pressure range is: 200 to 600 MPa, preferably 300 to 400 MPa; the holding time is: 5 to 30 minutes; the molding temperature is: room temperature to 50°C, usually at room temperature. The powder particles are evenly compacted without internal defects, which is conducive to powder densification and high molding quality, and also avoids unnecessary phase changes of the powder particles during the molding process.

[0012] In the present invention, sintering is performed in a protective atmosphere (such as argon or nitrogen), or vacuum sintering; sintering temperature: 1000 to 1400°C, preferably 1100 to 1200°C; holding time: 1 to 5 hours, preferably 2 to 4 hours. Sufficient metallurgical bonding is formed between powder particles, the structure is uniform and completely dense, oxidation of the material is prevented, and the density and strength of the flange are further enhanced.

[0013] In the present invention, the hot isostatic pressing treatment is carried out in a protective atmosphere (such as argon or nitrogen); the pressure range is 100 to 200 MPa, usually 120 to 160 MPa; the temperature range is 900 to 1300°C, usually 1100 to 1200°C; the holding time is 1 to 3 hours, usually 1.5 to 2.5 hours. After sintering, the flange blank is further densified by the hot isostatic pressing process at high temperature and high pressure, which is conducive to eliminating pores and densifying materials, promoting further densification of the organization, uniform and defect-free internal structure, and improving the final density and mechanical properties of the flange.

[0014] In the present invention, steam treatment is performed at a steam pressure range of 30-80KPa, usually 40-60KPa; a temperature range of 560-600°C, usually 565-570°C; and a holding time of 1 to 8 hours, usually 2-3 hours. Further steam treatment allows water vapor to fully contact the internal voids of the workpiece, fill the voids to form closed pores, and facilitate higher density and mechanical properties of the flange after hot isostatic pressing, and also meet higher air tightness and corrosion resistance.

[0015] Compared with the traditional process, the present invention has significant advantages in the following aspects: 1. High material utilization rate: Due to the adoption of efficient powder metallurgy process, the present invention greatly reduces material waste, improves material utilization rate and reduces production cost.

[0016] 2. Manufacturability of complex shapes: Through the combination of cold isostatic pressing and hot isostatic pressing, the present invention can manufacture compressor flanges with complex geometric shapes, breaking through the limitations of traditional manufacturing processes on shape complexity.

[0017] 3. Excellent mechanical properties: The flange prepared by the present invention has high density, uniform structure and excellent mechanical properties, can meet the requirements of high strength and pressure resistance, and significantly prolong the service life of the product.

[0018] 4. Good air tightness: The flange prepared by the present invention has very high air tightness, and no gas leakage will occur under long-term high pressure conditions; 5. Improved production efficiency: By organically combining spray granulation, cold isostatic pressing, sintering and hot isostatic pressing, and steam treatment, the present invention simplifies the production process, shortens the production cycle, and greatly improves the production efficiency while ensuring the high quality of the flange.

[0019] In summary, the present invention provides a method for preparing compressor flanges that is efficient, environmentally friendly and has excellent performance through an innovative powder metallurgy process, and provides important technical support for the manufacture of key components of compressors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The flange is prepared by powder metallurgy of the present invention, after sintering.

[0021] Figure 2 The flange is prepared by powder metallurgy according to the present invention and is steam treated. DETAILED DESCRIPTION

[0022] Although powder metallurgy has advantages over forging, the biggest problem is that the performance of existing powder metallurgy flanges is much worse than that of forged products, and can only be downgraded or even cannot be used. The present invention improves the existing process for preparing powder flanges, first granulation, then cold isostatic pressing, sintering, hot isostatic pressing and steam treatment are carried out in sequence to obtain a compressor flange, and the key performance is equivalent to that of a forged flange, especially the air tightness is consistent, which solves the problem of poor air tightness of existing powder metallurgy flanges and overcomes the technical prejudice of the prior art that powder metallurgy products are not as good as forged products in air tightness.

[0023] Specifically, the powder metallurgy forming process of the compressor flange of the present invention is as follows: 1. Spray granulation: The premixed metal powder material (such as iron-based alloy) is made into granular powder through spray granulation equipment. The key parameters in the spray granulation process include: Spray gas pressure: 0.5 to 1.5 MPa; Granulation temperature: 50 to 200°C.

[0024] The obtained particles are uniform and well-shaped, with good flowability and uniformity.

[0025] The particle size obtained by spray granulation: the target particle D90 particle size is between 10 and 100 microns, preferably 30 to 70 microns, preferably 40 to 60 microns.

[0026] 2. Cold isostatic pressing: The granulated powder is placed in a flexible mold and pressed into shape by cold isostatic pressing. The main process parameters of cold isostatic pressing include: Pressure range: 200 to 600 MPa, usually 300 to 400 MPa; Holding time: 5 to 30 minutes; Molding temperature: room temperature to 50°C, usually at room temperature.

[0027] The powder particles are compacted uniformly without internal defects, the powder is densified and the molding quality is high, and any unnecessary phase changes of the powder particles during the molding process are avoided.

[0028] 3. Sintering: Sintering is performed in a protective atmosphere (such as argon or nitrogen) to further enhance the density and strength of the flange. The key parameters during the sintering process include: Sintering temperature: 1000 to 1400°C, generally 1100 to 1200°C; holding time: 1 to 5 hours, usually 2 to 4 hours.

[0029] Sufficient metallurgical bonding is formed between the powder particles, which is conducive to uniform and fully dense organization.

[0030] Sintering atmosphere: Argon, nitrogen or vacuum, keep the atmosphere purity above 99.99% to prevent material oxidation.

[0031] 4. Hot isostatic pressing: After sintering, the flange blank is further densified by hot isostatic pressing under high temperature and high pressure to eliminate the pores inside the material and improve the final density and mechanical properties of the flange. The process parameters of hot isostatic pressing include: Pressure range: 100 to 200 MPa, usually 150 MPa; Temperature range: 900 to 1300°C, usually 1100 to 1200°C; Holding time: 1 to 3 hours, usually 2 hours It is beneficial to completely eliminate pores and make the material dense, with a uniform internal structure and no defects.

[0032] Pressurized atmosphere: Argon or nitrogen.

[0033] 5. Steam treatment: The process parameters of steam treatment include: Steam pressure range: 30-80KPa, usually 40-60KPa; temperature range: 560-600℃, usually 565-570℃; holding time: 2 to 8 hours, usually 2-3h.

[0034] To ensure that water vapor can fully contact the internal voids of the workpiece, promote the full transformation of the workpiece into Fe3O4, and fill the voids to form closed pores.

[0035] The following is a detailed description of the technical progress of the present invention, the raw materials are existing products, and the specific preparation operations and performance tests are all conventional technologies. The iron-based alloy powder is C0.65%, MnS0.36%, Cu1.5%, and Fe balance. Example 1

[0036] Using iron-based alloy powder as raw material: First, the powder is made into spherical particles with a D90 particle size of 50 microns by spray granulation equipment; the spray gas pressure is 1MPa; the granulation temperature is 100℃, and the obtained particles are uniform and well-shaped, with good fluidity and uniformity; The particles are then placed in a mold and pressed at room temperature for 10 minutes at a pressure of 300 MPa using a cold isostatic pressing process to obtain a prefabricated flange blank; Then, it was sintered at 1100 °C for 2 h under argon protection; After sintering, the flange blank is placed in a hot isostatic pressing device with the temperature set to 1140°C and the pressure set to 150MPa for 2 hours to obtain a high-density compressor flange. Then put it into a steam furnace, 50KPa steam pressure, 560℃ for 2 hours to obtain the final flange.

[0037] Figure 1 This is a photo after sintering. Figure 2 This is a photo of the actual object after steam treatment.

[0038] Comparative Example 1 Iron-based alloy powder was selected as raw material, and the compressor flange was prepared according to the process route of Example 1, but without steam treatment. Microstructure analysis and mechanical property testing confirmed that the process can effectively improve the pressure resistance and fatigue strength of the titanium alloy flange, but the air tightness is reduced.

[0039] Comparative Example 2 Iron-based alloy powder is used as raw material, and conventional molding, sintering and steam treatment processes are used to obtain flange parts; wherein, molding is room temperature press molding, and sintering and steam treatment are the same as Example 1; this is the mainstream method in current production.

[0040] Comparative Example 3: Mainstream compressor forged flange available on the market.

[0041] Performance table:

[0042] It can be seen that in addition to the conventional performance of the powder metallurgy flange of the present invention being equivalent to that of the forged flange (it is generally believed that the performance retention rate is above 95%), unexpectedly, the air tightness of the powder metallurgy flange of the present invention is also equivalent to that of the forged flange, both meeting 5MPa, 30min, and can completely replace the existing forged flange. Example 2

[0043] Referring to the embodiment, after spray granulation, particles with D90 of 30 microns are obtained, and the rest are the same, to obtain a powder metallurgy flange, which has an air tightness of less than 5MPa, 30min, and is not as good as a forged flange. It can only be downgraded for use, that is, it cannot completely replace the existing forged flange.

[0044] Comparative Example 4 Referring to the embodiment, the hot isostatic pressing is omitted, and the rest are the same, to obtain a powder metallurgy flange, which has an airtightness of less than 4MPa, 30min, and is inferior to the forged flange. It can only be downgraded for use and cannot be used in many occasions, that is, it cannot completely replace the existing forged flange.

[0045] Comparative Example 5 Referring to the embodiment, cold isostatic pressing is omitted, and the rest are the same, to obtain a powder metallurgy flange, which has an airtightness of less than 4MPa, 30min, and is inferior to a forged flange. It can only be downgraded for use and cannot be used in many occasions, that is, it cannot completely replace the existing forged flange.

[0046] The method of the present invention can produce special-shaped flanges with high density, uniform structure and excellent mechanical properties. Similarly, special-shaped powder metallurgy parts with high density requirements can also be produced. Powder metallurgy parts with extremely high air tightness requirements can also be produced by the method of the present invention. The batch stability is good and the efficiency is high.

Claims

1. A powder metallurgy forming process for a compressor flange, characterized in that: The method comprises the following steps: the metal powder is spray granulated and then subjected to cold isostatic pressing, sintering, hot isostatic pressing and steam treatment in sequence to obtain a compressor flange.

2. The powder metallurgy forming process of the compressor flange according to claim 1, characterized in that: The metal powder is iron-based metal powder.

3. The powder metallurgy forming process of the compressor flange according to claim 1, characterized in that: During spray granulation, the spray gas pressure is 0.5 to 1.5 MPa, and the granulation temperature is 50 to 200°C.

4. The powder metallurgy forming process of the compressor flange according to claim 1, characterized in that: After spray granulation, metal particles with a particle size of 10 to 100 microns are sequentially subjected to cold isostatic pressing, sintering, hot isostatic pressing and steam treatment to obtain a compressor flange.

5. The powder metallurgy forming process of the compressor flange according to claim 1, characterized in that: During cold isostatic pressing, the pressure range is: 200 to 600 MPa, the holding time is: 5 to 30 minutes, and the molding temperature is: room temperature to 50°C.

6. The powder metallurgy forming process of the compressor flange according to claim 1, characterized in that: Sintering is carried out in a protective atmosphere, and vacuum sintering is also possible; sintering temperature: 1000 to 1400°C, holding time: 1 to 5 hours.

7. The powder metallurgy forming process of the compressor flange according to claim 1, characterized in that: The hot isostatic pressing treatment is carried out in a protective atmosphere; the pressure range is 100 to 200 MPa, the temperature range is 900 to 1300°C, and the holding time is 1 to 3 hours.

8. The powder metallurgy forming process of the compressor flange according to claim 1, characterized in that: During steam treatment, the steam pressure range is: 30-80KPa, the temperature range is: 560-600℃, and the pressure holding time is: 1 to 8 hours.

9. A compressor flange manufactured by the powder metallurgy forming process of the compressor flange according to claim 1.

10. Use of the compressor flange according to claim 9 to replace the forged flange.

Images