A pollution-free heat treatment method and system for aluminum alloy parts with internal cavities

Abstract

This invention relates to a pollution-free heat treatment method for aluminum alloy parts with internal cavities, comprising: fabricating the aluminum alloy part; forming a blank with a closed internal cavity by diffusion brazing two grooved plates; opening a liquid filling hole at one end of the closed internal cavity and welding a liquid filling tube to the liquid filling hole; evacuating the closed internal cavity through the liquid filling tube, and then sealing the free end of the liquid filling tube; performing vacuum solution treatment on the vacuum-treated aluminum alloy part; cooling by filling a vacuum air quenching furnace with N2 after heat treatment; and performing aging treatment on the aluminum alloy part after exiting the furnace to form an aluminum alloy part with a tensile strength ≥300 MPa, a yield strength ≥250 MPa, and an elongation ≥8.0%. This invention enables aluminum alloy parts with internal cavities to meet strength requirements while ensuring that the internal cavity is pollution-free and the welds do not crack.

Description

Technical Field

[0001] This invention relates to a pollution-free heat treatment method for aluminum alloy parts with internal cavities, belonging to the field of aluminum alloy heat treatment technology. Background Technology

[0002] Thermal control technology is the technology that controls the heat exchange process between the internal and external environments of a satellite to keep its equilibrium temperature within a required range. It is an important component of aerospace technology. With the further development of aerospace technology, new satellites will face challenges such as the transfer and release of large amounts of heat, effective heat insulation, and maintaining low temperatures in cryogenic environments.

[0003] To meet the heat transfer requirements of the satellite's laser, a loop heat pipe is used to dissipate heat. Since a single laser contains three dispersed heat sources, the evaporator components cannot effectively cover all heat sources. Therefore, a steam cavity is proposed for heat collection, and it will be designed as an integrated unit to minimize thermal resistance and improve temperature uniformity among the hot spots. The component with the steam cavity is made of aluminum alloy in a T6 heat-treated state. Two grooved plates are first formed into a blank by diffusion brazing, creating the inner cavity. Due to the brazing temperature reaching 500℃, the material state of the blank changes from T6 to O, and the hardness decreases from 100-120 HB to 40-60 HB. This results in insufficient strength to meet the impact requirements of steam pressure during actual use.

[0004] To meet the usage requirements of the parts and improve their overall strength, T6 (solution treatment + artificial aging) heat treatment is necessary. However, T6 treatment for parts with internal cavities presents two problems: ① Because the cavity of a part with an internal cavity only has one filling hole, it is impossible to clean the cavity later. Therefore, water, oil, or other contaminants cannot enter during heat treatment, and severe oxidation is also unacceptable. If the filling hole is sealed directly, the gas in the cavity will expand due to heat during heating, causing excessive internal pressure, leading to part deformation or even weld cracking; ② The middle part of a part with an internal cavity consists entirely of welds. If the cooling rate is too fast during heat treatment quenching (e.g., water cooling), the welds will crack. If the cooling rate is too slow, a solid solution cannot form, and precipitation strengthening cannot be completed during subsequent aging, thus failing to effectively improve the part's strength. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a pollution-free heat treatment method for aluminum alloy parts with internal cavities, so that the aluminum alloy parts with internal cavities meet the strength requirements, while ensuring that the internal cavity is pollution-free and the weld does not crack.

[0006] The solution of the present invention is:

[0007] A pollution-free heat treatment method for aluminum alloy parts with internal cavities includes:

[0008] Manufacturing aluminum alloy parts: The upper and lower plates with grooves are brazed to form a blank with a closed inner cavity. A liquid filling hole is opened at one end of the closed inner cavity, and a liquid filling tube is welded on the liquid filling hole.

[0009] The sealed inner cavity is evacuated through the filling tube, and the free end of the filling tube is sealed after evacuation.

[0010] Vacuum solution treatment of aluminum alloy parts after vacuuming: Place the vacuumed aluminum alloy parts into a vacuum quenching furnace at room temperature and evacuate the vacuum quenching furnace. When the vacuum degree in the vacuum quenching furnace is less than 10Pa, start heating. The solution temperature is 460℃-530℃ and the holding time is 50-120min.

[0011] After the heat preservation is completed, N2 is introduced into the vacuum quenching furnace for cooling. The pressure inside the vacuum quenching furnace is controlled at 8-15 bar until the temperature inside the vacuum quenching furnace is less than 50℃-100℃ before the furnace is removed.

[0012] After the aluminum alloy parts are subjected to aging treatment, they are formed to meet the following requirements: tensile strength ≥300MPa, yield strength ≥250MPa, and elongation ≥8.0%.

[0013] Furthermore, the filling tube is made of pure aluminum and is at least 300mm long.

[0014] Furthermore, when evacuating the sealed inner cavity through the filling tube, the vacuum level is controlled within the range of 0.1-100 Pa.

[0015] Furthermore, when aging the aluminum alloy parts after they come out of the furnace, the aging temperature is 100-220℃ and the holding time is 8-24h.

[0016] Furthermore, when the vacuum level in the vacuum quenching furnace is less than 10 Pa, the heating rate is 5-15℃ / min.

[0017] A pollution-free heat treatment system for aluminum alloy parts with an internal cavity includes:

[0018] Aluminum alloy parts manufacturing module: The upper and lower plates with grooves are brazed to form a blank with a closed inner cavity. A liquid filling hole is opened at one end of the closed inner cavity, and a liquid filling tube is welded on the liquid filling hole.

[0019] Vacuum evacuation module for sealed inner cavity: Vacuum is evacuated into the sealed inner cavity through the filling tube, and the free end of the filling tube is sealed after evacuation;

[0020] Vacuum solution treatment module: The vacuum-evacuated aluminum alloy parts are placed in a vacuum quenching furnace at room temperature and the vacuum quenching furnace is evacuated. When the vacuum degree in the vacuum quenching furnace is less than 10Pa, heating is started. The solution treatment temperature is 460℃-530℃ and the temperature is held for 50-120 minutes.

[0021] Air-cooled module: After the heat preservation is completed, N2 is charged into the vacuum quenching furnace for cooling, and the pressure inside the vacuum quenching furnace is controlled at 8-15 bar until the temperature inside the vacuum quenching furnace is less than 50℃-100℃ before the furnace is removed.

[0022] Aging treatment module: After aging treatment, the aluminum alloy parts that have come out of the furnace are formed to meet the following requirements: tensile strength ≥300MPa, yield strength ≥250MPa, and elongation ≥8.0%.

[0023] The advantages of this invention compared to the prior art are:

[0024] (1) The present invention uses vacuum solid solution, which can effectively reduce the oxidation of aluminum alloy;

[0025] (2) The present invention uses high-pressure and high-purity gas cooling, which not only meets the cooling rate requirements during quenching, but also avoids excessive cooling rate causing thermal stress and weld cracking, and also avoids the introduction of contaminants;

[0026] (3) The present invention adopts the method of evacuating the inner cavity and sealing it, which avoids contamination of the inner cavity during the heating process and prevents the excessive pressure difference between the inside and outside during the heating process from causing deformation of the parts or even cracking of the weld. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the component structure of the present invention;

[0028] Figure 2 The heat treatment process flow of this invention is as follows. Detailed Implementation

[0029] The present invention will be further described below with reference to the embodiments.

[0030] A pollution-free heat treatment method for aluminum alloy parts with internal cavities, such as Figure 2 As shown, it includes:

[0031] Manufacturing aluminum alloy parts, such as Figure 1 As shown, two plates with grooves are made into a blank with a closed inner cavity by diffusion brazing. A liquid filling hole is opened at one end of the closed inner cavity, and a liquid filling tube is welded on the liquid filling hole. The liquid filling tube is made of pure aluminum and has a length of not less than 300mm.

[0032] The sealed inner cavity is evacuated through the filling tube, and the vacuum level is controlled within the range of 0.1-100Pa. After evacuation, the free end of the filling tube is sealed.

[0033] Vacuum solution treatment of aluminum alloy parts after vacuuming: Place the vacuumed aluminum alloy parts into a vacuum quenching furnace at room temperature and evacuate the vacuum quenching furnace. When the vacuum degree in the vacuum quenching furnace is less than 10Pa, start heating. The heating rate is 5-15℃ / min, the solution temperature is 460℃-530℃, and the holding time is 50-120min.

[0034] After the heat preservation is completed, N2 is introduced into the vacuum quenching furnace for cooling. The pressure inside the vacuum quenching furnace is controlled at 8-15 bar until the temperature inside the vacuum quenching furnace is less than 50℃-100℃ before the furnace is removed.

[0035] The aluminum alloy parts that have come out of the furnace are subjected to aging treatment at a temperature of 100-220℃ for 8-24 hours. After the aging process, they are cooled to room temperature to form aluminum alloy parts that meet the following requirements: tensile strength ≥300MPa, yield strength ≥250MPa, and elongation ≥8.0%.

[0036] Example 1: Heat treatment of vapor chamber saddle for 6061 aluminum alloy loop heat pipe

[0037] 1) Weld a liquid filling tube onto the liquid filling hole formed by diffusion brazing. The liquid filling tube is made of pure aluminum and is 320mm long.

[0038] 2) Use the filling tube to evacuate the inner cavity of the part to a vacuum level of 10 Pa. After evacuation, clamp the free end of the filling tube.

[0039] 3) Perform vacuum solution treatment on the parts, clean the surface of the saddle parts and blow dry, put them into a vacuum quenching furnace at room temperature and evacuate the vacuum. When the vacuum degree is less than 10Pa, start heating at a heating rate of 10℃ / min, the solution temperature is 525℃, and hold for 100min.

[0040] 4) After the heat preservation is completed, pressurize with high-pressure high-purity N2 for cooling at a pressure of 12 bar until the furnace temperature is less than 70°C before unloading.

[0041] 5) For aging, use an electric heating forced-air drying oven. Place the oven into the oven when the temperature reaches 165℃ and keep it warm for 10 hours. After the heat preservation is completed, remove the oven and air cool.

[0042] Example 2: Steam chamber heat treatment for 6063 aluminum alloy heat pipes

[0043] 1) Weld a liquid filling tube onto the liquid filling hole formed by diffusion brazing. The liquid filling tube is made of pure aluminum and is 320mm long.

[0044] 2) Use the filling tube to evacuate the inner cavity of the part to a vacuum level of 10 Pa. After evacuation, clamp the free end of the filling tube.

[0045] 3) Perform vacuum solution treatment on the parts, clean the surface of the saddle parts and blow dry, put them into a vacuum quenching furnace at room temperature and evacuate the vacuum. When the vacuum degree is less than 10Pa, start heating at a heating rate of 8℃ / min, the solution temperature is 525℃, and hold for 80min.

[0046] 4) After the heat preservation is completed, pressurize with high-pressure high-purity N2 for cooling. The pressure is 9 bar, until the furnace temperature is less than 70°C and then remove the furnace.

[0047] 5) For aging, use an electric heating forced-air drying oven. Place the oven into the oven when the temperature reaches 200℃ and keep it warm for 10 hours. After the heat preservation is completed, remove the oven and air cool.

[0048] Example 3: Heat treatment of 7075 aluminum alloy cavity parts

[0049] 1) Weld a liquid filling tube onto the brazed part. The liquid filling tube is made of pure aluminum and is 320mm long.

[0050] 2) Use the filling tube to evacuate the inner cavity of the part to a vacuum level of 10 Pa. After evacuation, clamp the free end of the filling tube.

[0051] 3) Perform vacuum solution treatment on the parts, clean the surface of the parts and blow dry, put them into a vacuum quenching furnace at room temperature and evacuate the vacuum. When the vacuum degree is less than 10Pa, start heating, heating rate is 6℃ / min, solution temperature is 470℃, and hold for 80min.

[0052] 4) After the heat preservation is completed, pressurize with high-pressure high-purity N2 for cooling at a pressure of 18 bar until the furnace temperature is less than 70°C before unloading.

[0053] 5) For aging, use an electric heating forced-air drying oven. Place the oven into the oven when the temperature reaches 120℃ and keep it warm for 24 hours. After the heat preservation is completed, remove the oven and air cool.

[0054] This invention employs vacuum solution treatment (usually air furnace solution treatment), which can effectively reduce the oxidation of aluminum alloys;

[0055] This invention uses high-pressure, high-purity N2 gas for cooling, which not only meets the cooling rate requirements during quenching, but also avoids excessive thermal stress caused by excessively rapid cooling, which could lead to weld cracking, and also avoids the introduction of contaminants.

[0056] This invention employs a method of evacuating and sealing the inner cavity to prevent contamination of the inner cavity during heating and to prevent excessive pressure difference between the inside and outside during heating, which could cause deformation of parts or even cracking of welds.

[0057] The heat treatment process of this invention can ensure that the mechanical properties meet the room temperature tensile mechanical property requirements of GB / T3880.1 while ensuring that the internal cavity of the part is free from contamination. Among them, the aluminum alloy products meet the requirements of tensile strength ≥300MPa, yield strength ≥250MPa, and elongation ≥8.0%.

[0058] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A pollution-free heat treatment method for aluminum alloy parts with internal cavities, characterized in that, include: Manufacturing aluminum alloy parts: The upper and lower plates with grooves are brazed to form a blank with a closed inner cavity. A liquid filling hole is opened at one end of the closed inner cavity, and a liquid filling tube is welded on the liquid filling hole. The sealed inner cavity is evacuated through the filling tube, and the free end of the filling tube is sealed after evacuation. Vacuum solution treatment of aluminum alloy parts after vacuuming: Place the vacuumed aluminum alloy parts into a vacuum quenching furnace at room temperature and evacuate the vacuum quenching furnace. When the vacuum degree in the vacuum quenching furnace is less than 10Pa, start heating. The solution temperature is 460℃-530℃ and the holding time is 50-120min. After the heat preservation is completed, N2 is introduced into the vacuum quenching furnace for cooling. The pressure inside the vacuum quenching furnace is controlled at 8-15 bar until the temperature inside the vacuum quenching furnace is less than 50℃-100℃ before the furnace is removed. After aging treatment, the aluminum alloy parts produced from the furnace are formed to meet the following requirements: tensile strength ≥300MPa, yield strength ≥250MPa, and elongation ≥8.0%.

2. The pollution-free heat treatment method for aluminum alloy parts with internal cavities according to claim 1, characterized in that, The filling tube is made of pure aluminum and is at least 300mm long.

3. The pollution-free heat treatment method for aluminum alloy parts with internal cavities according to claim 1, characterized in that, When evacuating the sealed inner cavity through the filling tube, the vacuum level should be controlled within the range of 0.1-100 Pa.

4. A pollution-free heat treatment method for aluminum alloy parts with internal cavities according to claim 1, characterized in that, When aging aluminum alloy parts after they come out of the furnace, the aging temperature is 100-220℃ and the holding time is 8-24h.

5. A pollution-free heat treatment method for aluminum alloy parts with internal cavities according to claim 1, characterized in that, When the vacuum level in the vacuum quenching furnace is less than 10 Pa, the heating rate is 5-15℃ / min.

6. A pollution-free heat treatment system for aluminum alloy parts with an internal cavity, characterized in that, include: Aluminum alloy parts manufacturing module: The upper and lower plates with grooves are brazed to form a blank with a closed inner cavity. A liquid filling hole is opened at one end of the closed inner cavity, and a liquid filling tube is welded on the liquid filling hole. Vacuum evacuation module for sealed inner cavity: Vacuum is evacuated into the sealed inner cavity through the filling tube, and the free end of the filling tube is sealed after evacuation; Vacuum solution treatment module: The vacuum-evacuated aluminum alloy parts are placed in a vacuum quenching furnace at room temperature and the vacuum quenching furnace is evacuated. When the vacuum degree in the vacuum quenching furnace is less than 10Pa, heating is started. The solution treatment temperature is 460℃-530℃ and the temperature is held for 50-120 minutes. Air-cooled module: After the heat preservation is completed, N2 is charged into the vacuum quenching furnace for cooling, and the pressure inside the vacuum quenching furnace is controlled at 8-15 bar until the temperature inside the vacuum quenching furnace is less than 50℃-100℃ before the furnace is removed. Aging treatment module: After aging treatment, the aluminum alloy parts that have come out of the furnace are formed to meet the following requirements: tensile strength ≥300MPa, yield strength ≥250MPa, and elongation ≥8.0%.

7. A pollution-free heat treatment system for aluminum alloy parts with an internal cavity according to claim 6, characterized in that, The filling tube is made of pure aluminum and is at least 300mm long.

8. A pollution-free heat treatment system for aluminum alloy parts with an internal cavity according to claim 6, characterized in that, When evacuating the sealed inner cavity through the filling tube, the vacuum level should be controlled within the range of 0.1-100 Pa.

9. A pollution-free heat treatment system for aluminum alloy parts with an internal cavity according to claim 6, characterized in that, When aging aluminum alloy parts after they come out of the furnace, the aging temperature is 100-220℃ and the holding time is 8-24h.

10. A pollution-free heat treatment system for aluminum alloy parts with an internal cavity according to claim 6, characterized in that, When the vacuum level inside the vacuum quenching furnace is less than 10 Pa, the heating rate is 5-15℃ / min.

Images