An ultra-high pressure hot isostatic pressing apparatus using liquid metal as a medium

Abstract

The utility model belongs to material processing technology field, concretely relates to a kind of superhigh pressure hot isostatic pressing equipment with liquid metal as medium, and it is applicable to the hot isostatic pressing treatment of titanium alloy and other additive manufacturing metal.The equipment includes working cylinder, upper end cover, heat shield, work platform, and the specific structure is as follows: the top opening of working cylinder is provided with upper end cover, the contact surface of upper end cover and working cylinder is designed as circular arc line, forming circular arc line contact hard seal;Working cylinder is equipped with work platform, heat shield is invertedly buckled on the outside of work platform, and the inner wall of lower part of heat shield is equipped with inner spiral heat insulation structure, and the outer wall of work platform corresponding to heat shield is equipped with matching outer spiral heat insulation structure, so that heat shield and work platform are connected by spiral, forming spiral heat preservation structure.The utility model realizes superhigh pressure fast cooling hot isostatic pressing technology by the principle of liquid metal heating expansion, without pressure increasing system, to improve the fatigue performance of additive manufacturing metal.

Description

Technical Field

[0001] This utility model belongs to the field of material processing technology, specifically relating to an ultra-high pressure hot isostatic pressing device using liquid metal as a medium, which is suitable for hot isostatic pressing of additive manufacturing metals such as titanium alloys. Background Technology

[0002] Additive manufacturing, as a strategic frontier technology of the 21st century, has enormous application potential in the field of high-end equipment manufacturing. Due to its unique technological processes, additive manufacturing inevitably introduces defects such as micropores into the material during the printing process. These defects have little impact on static tensile properties, but significantly reduce fatigue performance. Therefore, the fatigue performance of additively manufactured components under cyclic loading is generally much lower than that of traditional forgings, severely restricting their widespread application as load-bearing components in dynamic load structures. Generally, there are two main methods for controlling the size of defects in additive manufacturing: one is to optimize process parameters during printing, and the other is to perform hot isostatic pressing (HIP) on the printed components. Given that the former is difficult to eliminate or avoid defects of tens of micrometers, HIP is currently the mainstream method for repairing additive manufacturing defects in the industry. The effectiveness of HIP in healing defects is influenced by the coupling of pressure and temperature, which can compensate for each other to some extent. However, due to current technological limitations, the maximum pressure of current HIP equipment is generally less than 200 MPa, which is very limited compared to the strength of common materials. This leads to the need for very high temperature treatments to achieve micropore healing for metallic structural materials such as titanium alloys, high-temperature alloys, and steel. At high temperatures, the microstructure of metallic materials inevitably coarsens, severely weakening their fatigue performance. While some materials (such as titanium alloys) can have their microstructure refined to some extent through subsequent heat treatment, this may lead to the reappearance of porosity or even the enrichment of α-phase at grain boundaries, resulting in new adverse factors and preventing effective improvement in fatigue performance. Furthermore, the cooling rate of traditional HIP (High-Intensity Interruption) systems is severely limited, with most cooling methods being furnace-based cooling, which greatly restricts the controllability of the material microstructure during the cooling process. Therefore, overcoming technical bottlenecks such as ultra-high pressure sealing and rapid cooling, and developing a new generation of ultra-high pressure (≥400MPa) rapid-cooling HIP equipment, is not only a solution to the core bottleneck of fatigue-resistant additive manufacturing but also a necessity for the development of HIP technology itself.

[0003] Patent CN111572087A discloses an isostatic press using water as the medium, which cannot withstand high temperatures (it does not involve the high-temperature environment of hot isostatic pressing) and is only suitable for cold / warm isostatic pressing, failing to achieve high-temperature defect healing in metallic materials. Patents CN213767339U and CN111360260A employ liquid metal medium hot isostatic pressing technology, relying on a booster to achieve pressure. The operating pressure is ≤200MPa, unable to break through ultra-high pressure (≥400MPa), requiring high temperatures to promote defect healing, leading to material coarsening. Utility Model Content

[0004] To address the aforementioned technical problems, this utility model aims to provide an ultra-high pressure hot isostatic pressing (HIP) device using liquid metal as the medium. It is designed to tackle the bottleneck problem of fatigue performance in additive manufacturing components, developing an ultra-high pressure HIP device suitable for fatigue-resistant treatment of additive manufacturing metals. By breaking through key technologies such as ultra-high pressure gas sealing technology and forced rapid cooling technology, the upper limit pressure of HIP is increased by more than 100% (working pressure ≥ 400 MPa). While achieving defect healing, it also maximizes the refinement of the microstructure, thereby significantly improving the fatigue performance of additive manufacturing metals.

[0005] The technical solution adopted in this utility model is as follows:

[0006] An ultra-high pressure hot isostatic pressing device using liquid metal as the medium includes a working cylinder, an upper end cover, a heat insulation cover, and a working platform. The specific structure is as follows: The upper end cover is installed at the top opening of the working cylinder, and the contact surface between the upper end cover and the working cylinder is designed as an arc, forming an arc-shaped contact hard seal; a working platform is installed inside the working cylinder, and the heat insulation cover is inverted on the outside of the working platform. The lower inner wall of the heat insulation cover is provided with an inner spiral heat insulation structure, and the outer wall of the working platform corresponding to the heat insulation cover is provided with a matching outer spiral heat insulation structure, so that the heat insulation cover and the working platform are connected by a spiral to form a spiral heat insulation structure.

[0007] The ultra-high pressure hot isostatic pressing equipment using liquid metal as a medium has a pressure sensor on the lower side of the working cylinder cavity, and a temperature sensor and a heating wire on the upper part of the heat insulation cover cavity. The heating wire serves as a heat source to directly heat the liquid metal, causing the liquid metal to expand due to heat and achieve self-pressurization.

[0008] The ultra-high pressure hot isostatic pressing equipment using liquid metal as the medium has an insulating medium coated on the surface of the heating wire to prevent electrical conduction between the heating wire and the liquid metal.

[0009] The ultra-high pressure hot isostatic pressing equipment using liquid metal as a medium has a water cooling system installed around the working cylinder. The working cylinder and the water cooling system are surrounded by a steel wire layer, which applies a pre-compression force to the working cylinder to counteract the circumferential tensile stress generated by the internal pressure.

[0010] The ultra-high pressure hot isostatic pressing equipment using liquid metal as the medium has an ultra-high pressure valve installed on the upper end cover, and a liquid metal inlet and outlet are provided at the bottom of the working cylinder. The ultra-high pressure valve controls the liquid metal to fill the entire working cylinder cavity before heating. After the heat preservation and pressure holding stage of hot isostatic pressing is completed, the ultra-high pressure valve instantly releases the liquid metal pressure in the working cylinder to achieve rapid pressure relief.

[0011] An ultra-high pressure hot isostatic pressing method using liquid metal as the medium includes the following steps:

[0012] (1) Fix the workpiece to be processed on the work platform. Liquid metal enters the working cylinder through the liquid metal inlet and outlet. The liquid metal fills the entire working cylinder. Then cover the work platform and the workpiece to be processed with a heat insulation cover and install the upper end cover.

[0013] (2) Use an electric heating wire to heat the liquid metal inside the heat insulation cover. As the liquid metal expands when heated, the liquid metal in the working cylinder will generate pressure. When heated to 600-800℃, record the pressure value at this time as 400-1000MPa. Keep the temperature and pressure at this time for 30min-2h.

[0014] (3) After the heat preservation time is completed, stop heating with the electric heating wire, depressurize the liquid metal in the working cylinder through the ultra-high pressure valve, and let the liquid metal flow back through the liquid metal inlet and outlet. At the same time, start the external water cooling system to cool the working cylinder, and take out the processed workpiece for oil quenching, water quenching or air cooling.

[0015] An ultra-high pressure hot isostatic pressing method using liquid metal as the medium includes the following steps:

[0016] (1) Fix the workpiece to be processed on the work platform. Liquid metal enters the working cylinder through the liquid metal inlet and outlet. The liquid metal fills the entire working cylinder. Then cover the work platform and the workpiece to be processed with a heat insulation cover and install the upper end cover.

[0017] (2) Use an electric heating wire to heat the liquid metal inside the heat insulation cover. As the liquid metal expands when heated, the liquid metal in the working cylinder will generate pressure. When heated to 600-800℃, record the pressure value at this time as 400-1000MPa. Keep the temperature and pressure at this time for 30min-2h.

[0018] (3) After the heat preservation time is completed, stop heating with the electric heating wire, depressurize the liquid metal in the working cylinder through the ultra-high pressure valve, and let the liquid metal flow back through the liquid metal inlet and outlet. At the same time, start the external water cooling system to cool the working cylinder, and take out the processed workpiece for oil quenching, water quenching or air cooling.

[0019] The design concept of this utility model is:

[0020] Existing HIP (High-Intensity Isostatic Pressing) equipment suffers from insufficient pressure (≤200MPa), requiring extremely high temperatures to heal micropores in additive manufacturing, leading to coarsening of the microstructure and decreased fatigue performance. Furthermore, slow cooling in gaseous or liquid media hinders rapid microstructure refinement. This invention proposes a novel approach to fatigue resistance through synergistic regulation of microstructure and defects. It develops ultra-high pressure rapid cooling hot isostatic pressing technology and equipment. By significantly increasing the pressure of current hot isostatic pressing processes while reducing the processing temperature, and utilizing pressure to generate temperature, along with increasing the cooling rate, it achieves the effect of refining the material microstructure while healing defects. This allows for synergistic regulation of microstructure and defects in a single process, improving the fatigue performance of additively manufactured metals.

[0021] This utility model has the following advantages and beneficial effects:

[0022] 1. This utility model does not require a pressurization system. It uses liquid metal as the pressure transmission medium and achieves higher pressure (up to 1000 MPa) for medium and low temperature (600-800℃) HIP treatment by means of the heating and expansion of the liquid metal itself. This allows for the exchange of pressure for temperature, thereby reducing the treatment temperature, inhibiting lath coarsening and avoiding tissue coarsening.

[0023] 2. This utility model can quickly depressurize at high temperatures, and the components can be water-quenched / air-cooled. The faster cooling speed can make the material's structural defects better matched, achieving the desired result in one step.

[0024] 3. The outer spiral heat insulation structure of the working platform of this utility model and the inner spiral heat insulation structure of the heat insulation cover work together to form a heat-insulating labyrinth, so as to achieve a good heat insulation effect and achieve the purpose of heat-pressure separation. The cavity outside the heat insulation cover does not have such a high temperature and only needs to withstand high pressure. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the technical principle of the ultra-high pressure hot isostatic pressing equipment using liquid metal as the medium.

[0026] Figure 1 The attached diagrams are labeled as follows: 1. Upper end cover, 2. Ultra-high pressure valve, 3. Heat insulation cover, 4. Heating wire, 5. Water cooling system, 6. Steel wire layer, 7. Pressure sensor, 8. Working platform, 9. Spiral insulation structure, 10. Temperature sensor, 11. Liquid metal, 12. Working cylinder, 13. Liquid metal inlet and outlet, 14. Inner spiral insulation structure, 15. Outer spiral insulation structure. Detailed Implementation

[0027] like Figure 1As shown, this utility model proposes an ultra-high pressure thermal isostatic pressing device using liquid metal as the medium, mainly including an upper end cover 1, an ultra-high pressure valve 2 (working pressure ≥400MPa), a heat insulation cover 3, a heating wire 4, a water cooling system 5, a steel wire layer 6, a pressure sensor 7, a working platform 8, a spiral insulation structure 9, a temperature sensor 10, liquid metal 11, a working cylinder 12, etc., with the specific structure as follows:

[0028] The top opening of the working cylinder 12 is fitted with an upper end cap 1. The contact surface between the upper end cap 1 and the working cylinder 12 is designed as an arc, forming a linear contact to reduce the contact area and enhance the sealing effect. This is a hard seal with an arc contact, made of hard alloy that cannot react with liquid metal. An ultra-high pressure valve 2 is installed on the upper end cap 1. The bottom of the working cylinder 12 has a liquid metal inlet / outlet 13. The ultra-high pressure valve 2 controls the filling of the entire working cylinder 12 cavity with liquid metal 11 before heating. After the HIP heat preservation and pressure holding stage, the liquid metal pressure of ≥400MPa in the working cylinder is released instantly, achieving rapid pressure relief.

[0029] The working cylinder 12 is equipped with a working platform 8. The heat insulation cover 3 is upside down on the outside of the working platform 8. The lower inner wall of the heat insulation cover 3 is equipped with an inner spiral heat insulation structure 14. The outer wall of the working platform 8 corresponding to the heat insulation cover 3 is equipped with a matching outer spiral heat insulation structure 15, so that the heat insulation cover 3 and the working platform 8 are connected by a spiral to form a spiral heat preservation structure 9 (heat preservation labyrinth).

[0030] A pressure sensor 7 is provided on the lower side of the cavity of the working cylinder 12 to monitor the precise pressure value (≥400MPa) reached by the liquid metal in real time and directly during the heating and holding stages. Medium and low temperature HIP treatment is achieved by increasing the pressure.

[0031] A water-cooling system 5 is installed around the working cylinder 12 to cool it down, allowing the workpiece to enter a rapid cooling state immediately after the HIP heat preservation and pressure holding process, thus inhibiting grain growth and refining the microstructure. A steel wire layer 6 is wound around the working cylinder 12 and the water-cooling system 5. This steel wire layer 6 applies a certain pre-compression force to the working cylinder, counteracting the circumferential tensile stress generated by the internal pressure and ensuring the long-term safe operation of the equipment under ultra-high pressure cyclic loads.

[0032] A temperature sensor 10 and a heating wire 4 are respectively installed on the upper part of the heat insulation cover 3 cavity. The heating wire 4 serves as a heat source, directly heating the liquid metal, causing the liquid metal to expand due to heat. This generates an ultra-high pressure of ≥400MPa without the need for mechanical pressurization, achieving a "self-pressurization" process. The heating wire needs to be coated with an insulating medium such as ceramic to prevent electrical conductivity between the heating wire and the liquid metal. The temperature sensor 10 monitors the temperature of the liquid metal in the heat insulation cover 3 cavity in real time, ensuring that the heating temperature is accurately maintained between 600 and 800℃.

[0033] The present invention will be further described in detail below through embodiments.

[0034] Example

[0035] like Figure 1 As shown, this embodiment proposes an ultra-high pressure hot isostatic pressing method for titanium alloy workpieces using liquid metal as the medium, including the following steps:

[0036] (1) Fix the workpiece to be processed onto the work platform 8. Liquid metal 11 (liquid tin or its alloy) enters the working cylinder 12 through the liquid metal inlet and outlet 13. The liquid metal fills the entire working cylinder 12. Then cover the work platform 8 and the workpiece to be processed with a heat insulation cover and cover the upper end cover 1.

[0037] (2) Use the heating wire 4 to heat the liquid metal 11 inside the heat insulation cover 3. Since the liquid metal will expand when heated, the liquid metal 11 in the working cylinder 12 will generate pressure. When it is heated to a certain temperature, record the pressure value at this time. Keep it warm for a period of time at this temperature and pressure.

[0038] (3) After the heat preservation time is completed, the heating wire 4 is stopped, and the liquid metal 11 in the working cylinder 12 is depressurized through the ultra-high pressure valve 2. The liquid metal 11 flows back quickly through the liquid metal inlet and outlet 13. At the same time, the peripheral water cooling system 5 is started to cool the working cylinder 12, inhibit grain growth and refine the structure. The processed workpiece is taken out for water quenching.

[0039] The results show that this invention solves the technical problem that traditional technologies cannot simultaneously achieve ultra-high pressure, rapid cooling and microstructure control through the synergistic effect of liquid metal self-pressurization, thermal labyrinth and direct cooling (such as quenching). It achieves defect healing and grain refinement in one step, avoiding the need for multiple heat treatments in traditional methods, which can easily lead to defects such as porosity.

Claims

1. An ultra-high pressure hot isostatic pressing device using liquid metal as the medium, characterized in that, The system includes a working cylinder, an upper cover, a heat insulation cover, and a working platform. The specific structure is as follows: The upper cover is installed at the top opening of the working cylinder. The contact surface between the upper cover and the working cylinder is designed as an arc, forming an arc-shaped contact hard seal. The working cylinder contains a working platform. The heat insulation cover is inverted and placed on the outside of the working platform. The lower inner wall of the heat insulation cover has an inner spiral heat insulation structure. The outer wall of the working platform, corresponding to the heat insulation cover, has a matching outer spiral heat insulation structure. The heat insulation cover and the working platform are connected by a spiral to form a spiral heat insulation structure.

2. The ultra-high pressure hot isostatic pressing equipment using liquid metal as the medium according to claim 1, characterized in that, A pressure sensor is installed on the lower side of the working cylinder cavity, and a temperature sensor and a heating wire are installed on the upper part of the heat shield cavity. The heating wire serves as a heat source to directly heat the liquid metal, causing the liquid metal to expand due to heat and achieve self-pressurization.

3. The ultra-high pressure hot isostatic pressing equipment using liquid metal as the medium according to claim 2, characterized in that, The surface of the heating wire is coated with an insulating medium to prevent electrical conductivity between the heating wire and the liquid metal.

4. The ultra-high pressure hot isostatic pressing equipment using liquid metal as the medium according to claim 1, characterized in that, A water cooling system is installed around the working cylinder. A steel wire layer is wrapped around the working cylinder and the water cooling system. The steel wire layer applies a pre-compression force to the working cylinder to counteract the circumferential tensile stress generated by the internal pressure.

5. The ultra-high pressure hot isostatic pressing equipment using liquid metal as the medium according to claim 1, characterized in that, The upper end cover is equipped with an ultra-high pressure valve, and the bottom of the working cylinder is equipped with a liquid metal inlet and outlet. The ultra-high pressure valve controls the liquid metal to ensure that the entire working cylinder cavity is filled with liquid metal before heating. After the hot isostatic pressing and heat preservation stage is completed, the ultra-high pressure valve instantly releases the liquid metal pressure in the working cylinder to achieve rapid pressure relief.

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