CN104226870B - A kind of cladding method of the hip moulding for aluminum-stainless steel composite pipe - Google Patents

Abstract

The invention belongs to the technical field of metal composite material preparation, in particular to a wrapping method for hot isostatic pressing of aluminum-stainless steel composite pipes. The specific steps of the method of the present invention are as follows: 1. preparing the sheath assembly; 2. pre-assembly treatment of the sheath assembly and the aluminum-stainless steel composite pipe assembly; 3. assembly and welding of the sheath assembly and the aluminum-stainless steel composite pipe assembly; 4. the obtained sheath degassing and sealing. The sheath of the present invention can isolate the environment inside the sheath from the environment outside the sheath during the hot isostatic pressing process of high temperature and high pressure, and maintain good sealing performance; it can realize the uniform action of argon pressure in the hot isostatic pressing process At the interface between the metal layers of the aluminum-stainless steel composite pipe; it can ensure that after the hot isostatic pressing of the aluminum-stainless steel composite pipe, the size and shape tolerance of the stainless steel inner hole will not be larger than that before the hot isostatic pressing treatment. Deviate.

Description

A wrapping method for hot isostatic pressing of aluminum-stainless steel composite pipe

technical field

The invention belongs to the technical field of metal composite material preparation, in particular to a wrapping method for hot isostatic pressing of aluminum-stainless steel composite pipes.

Background technique

For the flexible heat pipes, single-phase and two-phase liquid heat transfer circuits, and expandable heat radiators used in space vehicles, the working medium circulation pipelines and storage containers are made of stainless steel based on considerations of strength and corrosion resistance. In addition, in the area of heat collection (evaporation of heat transfer medium) and heat dissipation (condensation of heat transfer medium), based on the consideration of heat transfer performance and weight, the aluminum material expansion box with light weight, good heat transfer performance and large specific heat capacity is selected in the design. hot plate. The heat flux density at the interface between the stainless steel tube shell and the aluminum alloy heat expansion plate in the heat transfer fluid evaporation and condensation area of the thermal control system can reach several watts per square centimeter, and methods such as mechanical bonding or filling with thermal grease and thermal adhesive cannot meet the heat transfer performance requirements However, the common brazing process is also difficult to realize the large-area metallurgical combination of the heat pipe shell and the heat expansion plate so as to achieve the purpose of high-efficiency heat transfer. The solution to the above problems is to prepare a composite pipe made of aluminum alloy and stainless steel for use in the evaporation and condensation regions of the heat transfer working medium of the thermal control system. The structure of the composite pipe is that the stainless steel pipe is inside as a circulation pipeline for heat transfer working medium, and the aluminum alloy pipe is outside as a heat expansion plate. In addition, the composite pipe should also meet the following requirements: 1. The interface between stainless steel and aluminum alloy is metallurgically bonded; 2. The metallurgical bonding rate of the interface is greater than 90%; 3. The shear strength of the interface is greater than 20MPa; 4. It meets the mechanical adaptability requirements of spacecraft products , through the random vibration environment test. 5. Meet the thermal environment adaptability requirements of spacecraft products.

According to the requirements of thermal control systems such as flexible heat pipes for aerospace vehicles, single-phase and two-phase liquid heat transfer circuits, and expandable heat radiators for aluminum-stainless steel composite pipes with light weight, pressure resistance, and high heat transfer capacity, several possibilities for such pipes The preparation process is introduced as follows: 1. Casting process. Design a special casting mold with stainless steel tube as the core, and cast the aluminum tube outside the core. The disadvantage of this process is that the aluminum liquid pouring temperature is higher (generally higher than 680 ° C), and the aluminum/stainless steel interface produces a thicker iron-aluminum intermetallic compound reaction layer. During the cooling process, the reaction layer occurs under the action of thermal stress. Penetrating cracking (the thermal expansion coefficient of aluminum alloy is about 23.4×10 ^-6 /℃, the thermal expansion coefficient of austenitic stainless steel is about 16.6×10 ^-6 /℃, and the aluminum/stainless steel interface will generate large thermal stress during the casting cooling process ) The bonding strength of the aluminum/stainless steel interface is low; 2. Welding process. The feature of this process is to fill the interface area between the stainless steel tube and the aluminum tube with solder with a lower melting point and corresponding flux, such as tin-based and lead-based solder. The solder layer with a certain thickness at the aluminum/stainless steel interface can reduce and eliminate the thermal stress generated during the cooling process of the aluminum-stainless steel weldment through its own yield deformation while realizing the metallurgical bonding of the aluminum-stainless steel interface. The aluminum-stainless steel interface of the composite pipe prepared by this process has higher bonding strength, and the pipe has better adaptability to aerospace mechanics and thermal environment. The disadvantage of this process is that soldering solder generally needs to be used in conjunction with flux. Flux plays a very important role in the welding process. In addition to removing the oxide film on the surface of the base metal to be welded, it also protects the welding environment. For the composite (welding) of aluminum/stainless steel pipe materials, only cream solder (a paste mixture of flux, solder, etc.) or other forms of solder and flux can be used for interface filling. During the welding process, the flux will generate a large amount of gas. In the form of such a slender and close interface structure of the composite pipe, it is very difficult to exhaust, and the gas pressure at the interface increases, which will cause the liquid solder to squeeze out, resulting in a low metallurgical bonding rate (brazing rate) at the interface. Not higher than 40%. 3. Extrusion molding process. After the stainless steel tube is assembled with the aluminum billet, it is loaded into the extrusion cylinder of the extrusion machine for extrusion molding. The extrusion molding process deforms a certain amount of the interface area of the aluminum and stainless steel tubes respectively, and the fresh surfaces of the two achieve the interface metallurgical bonding under the action of higher temperature and larger vertical compressive stress and have a higher bonding rate. The disadvantage of this process is that the deformation of the stainless steel tube cannot be accurately controlled during the extrusion process, resulting in the deviation of the wall thickness, roundness of the inner hole, and coaxiality of the inner hole of the stainless steel tube. 4. The drawing forming process is that the aluminum tube is fixed and restrained, and the stainless steel tube is drawn into the inner hole of the aluminum tube. If the metallurgical bonding of the aluminum-stainless steel interface is to be realized, the aluminum-stainless steel interface area must have a large amount of deformation and expose a fresh surface, and it can only be realized under the action of a large compressive stress in the vertical direction of the interface. The disadvantage of this process is that the fixed and constrained aluminum tube cannot produce large deformation, and the large deformation has a serious impact on the dimensions and tolerances of the stainless steel tube such as wall thickness, inner hole roundness, and inner hole coaxiality. 5. Hot isostatic pressure diffusion welding forming process. The specific operation of this process is to assemble, weld and vacuum-seal the composite tube components (stainless steel tube, interfacial transition layer metal, aluminum tube) and the package component, and then put the package into the hot isostatic pressing equipment for heat treatment, composite The three-layer metal interface of the tube realizes diffusion bonding under high pressure, high temperature and high vacuum environment. The molding process specifically has the following characteristics:

(1) Hot isostatic pressing is the pressure of gas, the pressure is hydrostatic pressure, and the pressure is applied to the three-layer metal interface of the composite pipe through the jacket. This process is very suitable for the material compounding of the pipe structure, and can achieve 90~ 100% interface recombination rate;

(2) The hot isostatic pressing method is very beneficial to improve the stress state of the three-layer metal interface of the composite pipe and improve the plastic deformation capacity of the interface;

(3) Hot isostatic pressing process parameters such as temperature, pressure, time, etc. can be adjusted flexibly, which is very beneficial to control the material structure of the bonding interface.

The task of the present invention is to develop a hot isostatic pressing sheath and a sheathing process for hot isostatic pressing of an aluminum-stainless steel composite pipe used for thermal control of a space vehicle. The sheath can isolate the environment inside the sheath from the environment outside the sheath during the high-temperature, high-pressure hot isostatic pressing process, and maintain good sealing; it can realize the uniform action of argon pressure through the sheath during the hot isostatic pressing process At the interface between the metal layers of the composite pipe in the sleeve; it can ensure that after the hot isostatic pressing of the composite pipe, the size and shape tolerance of the stainless steel inner hole will not deviate greatly from that before the hot isostatic pressing.

Contents of the invention

Aiming at the problem of hot isostatic pressing of aluminum-stainless steel composite pipes for thermal control of space vehicles, the invention provides a wrapping method for hot isostatic pressing of aluminum-stainless steel composite pipes.

A wrapping method for hot isostatic pressing of aluminum-stainless steel composite pipes, the specific steps of which are as follows:

①Prepare package components;

② Pre-assembly treatment of sheath components and aluminum-stainless steel composite pipe components;

③Assembly and welding of sheath components and aluminum-stainless steel composite pipe components;

④ Degassing and sealing of the obtained bag.

The sheath assembly includes: a vacuum sheath shell, a first outer end cap of the vacuum sheath, a first inner end cap of the vacuum sheath, a second inner end cap of the vacuum sheath, a second outer end cap of the vacuum sheath, and a vacuum sheath Set of exhaust pipes.

The aluminum-stainless steel composite pipe assembly includes: an aluminum alloy pipe, a transition layer metal and a stainless steel pipe.

The sheathing component is made of copper or silver, the purity of the copper or silver is greater than 99.9wt%, and the oxygen content is not greater than 50ppm. Copper and silver metals with higher purity have lower yield strength and good plastic deformation ability. The present invention utilizes the above-mentioned characteristics of copper and silver materials, and uses them as the material of the sheathing component. During the hot isostatic pressing process, the argon pressure of the medium acts uniformly on the three-layer metal interface of aluminum, transition layer metal and stainless steel through the copper or silver sheath. In addition, due to the good plastic deformation ability of copper and silver, the sheath can still maintain the sealing of the environment inside the sheath even when a large deformation occurs.

In order to maintain the insulation between the inner and outer environments of the sheath and good deformation ability during the hot isostatic pressing process, the wall thickness of each component of the sheath assembly is 0.5 mm to 5 mm.

The pre-assembly processing method of the package assembly is as follows: a. surface oxide layer removal; b. cleaning and degreasing; c. dehydration and drying; d. hydrogen burning treatment or thermal vacuum degassing; e. protected storage. The main purpose of the pre-treatment of hydrogen burning and thermal vacuum degassing in the assembly of packaged components is to purify the surface of the component, high-temperature softening annealing of the component, and degassing of the component.

The hydrogen burning treatment process system of the package assembly: heat treatment under a hydrogen atmosphere, the treatment temperature is 350°C to 700°C, the treatment time is 2 to 5 hours, and the hydrogen dew point is -80°C to -40°C; The thermal vacuum degassing method for the module is as follows: under the condition that the vacuum degree is better than 5.0×10 ^-3 Pa, degassing at 350° C. to 700° C. for 2 to 5 hours.

The pre-assembly processing method of the aluminum-stainless steel composite pipe assembly is as follows: a. cleaning and degreasing; b. dehydration and drying; c. thermal vacuum degassing; d. protected storage. The main purpose of thermal vacuum degassing pretreatment for aluminum-stainless steel composite pipe assembly is to deeply degas the aluminum-stainless steel composite pipe assembly, reduce the amount of gas escaped from the jacket during hot isostatic pressing, and maintain a high temperature in the jacket. Vacuum.

The thermal vacuum degassing method of the aluminum-stainless steel composite pipe assembly is as follows: degassing at 100 to 600 degrees Celsius for 2 to 5 hours under the condition that the vacuum degree is better than 5.0×10 ^-3 Pa.

The sheath assembly and the aluminum-stainless steel composite pipe assembly are pre-assembled, and if they are not assembled and welded in time, they need to be stored under vacuum conditions, and the vacuum degree of the storage environment is better than 100Pa.

When the sheath assembly is assembled with the aluminum-stainless steel composite pipe assembly, the outer shell of the vacuum sheath is covered on the outer side of the aluminum alloy pipe; The end cap is assembled with the second inner end cap of the vacuum sheath; the two ends of the outer layer aluminum alloy tube of the aluminum-stainless steel composite pipe are respectively assembled with the first outer end cap of the vacuum sheath and the second outer end cap of the vacuum sheath; The inner end cover is connected to the adjacent outer end cover by welding; the outer end cover is connected to the adjacent vacuum sheath shell by welding; the vacuum sheath exhaust pipe is welded to the second outer end cover of the vacuum sheath; the vacuum The jacket exhaust pipe communicates with the gap between the jacket assembly and the aluminum-stainless steel composite pipe assembly.

The welding is completed by electron beam welding, plasma arc welding, argon arc welding, vacuum brazing or hydrogen shielded brazing; wherein the weld penetration depth of electron beam welding, plasma arc welding and argon arc welding is not less than 0.5mm , the filling depth of the solder joints of vacuum brazing and hydrogen shielded brazing methods is not less than 0.5mm.

The solder used in the vacuum brazing and hydrogen shielded brazing methods is electric vacuum solder; the electric vacuum solder is: AgCu, AgCuIn, AgCuPd, AgCuSn, AgCuNi, AuCu or AuNi system alloy material.

The gaps between the sheath assembly and the aluminum-stainless steel composite pipe assembly are not greater than 0.10mm. The control of the assembly gap has two requirements. One is to meet the welding requirements of the jacket; the other is that the hot isostatic pressing process is to eliminate the assembly gap of the jacket and the components of the aluminum-stainless steel composite pipe. A small assembly gap can make After the hot isostatic pressing of the sheath and the aluminum-stainless steel composite components is completed, the deformation is small, which is conducive to ensuring the size and shape tolerance accuracy of the inner hole of the aluminum-stainless steel composite pipe (stainless steel pipe).

The degassing method of the sheath is as follows: after the welding of the sheath is completed, connect the air extraction device through the vacuum sheath exhaust pipe, and perform thermal vacuum degassing in the sheath. The main purpose of this process is to further reduce the amount of gas escaping from the sheath during heat treatment and maintain a high degree of vacuum in the sheath.

The thermal vacuum degassing method is as follows: under the condition of 100 to 600 degrees Celsius, the vacuum degree of the envelope is better than 10 ^-3 Pa, and the vacuum is maintained for more than 2 hours.

The sealing method of the sheath is as follows: after the degassing of the sheath is completed, use pressure welding pliers to pinch off the vacuum sheath exhaust pipe and weld the port.

The beneficial effects of the present invention are:

1. It can realize the isolation of the inner and outer environment of the sheath during the whole process of hot isostatic pressing, and the sheath maintains good sealing;

2. During the hot isostatic pressing process, the pressure of the argon medium can evenly act on the metal interface of each layer of the composite pipe in the sleeve through the sleeve;

3. It can ensure that after the hot isostatic pressing treatment of the composite pipe, the size and shape tolerance of the inner hole of the stainless steel will not deviate greatly from that before the hot isostatic pressing treatment;

4. In addition to being used for the thermal control of aluminum and stainless steel composite pipes for space vehicles, it can also be applied to the composite molding of other bimetallic pipes.

Description of drawings

Fig. 1 is the envelope structure schematic diagram that the present invention is used for the hot isostatic pressing of aluminum-stainless steel composite pipe;

Labels in the figure: 1-vacuum sheath shell; 2-vacuum sheath first outer end cap; 3-vacuum sheath first inner end cap; 4-vacuum sheath second inner end cap; 5-vacuum sheath second Two outer end caps; 6-vacuum sheath exhaust pipe; 7-aluminum alloy tube; 8-transition metal layer; 9-stainless steel tube; 10-the first welding seam of the vacuum sheath; 12-the third welding seam of vacuum sheath; 13-the fourth welding seam of vacuum sheathing; 14-the fifth welding seam of vacuum sheathing; 15-the sixth welding seam of vacuum sheathing; 16-the seventh welding seam of vacuum sheathing.

detailed description

The present invention provides a wrapping method for hot isostatic pressing of aluminum-stainless steel composite pipes. The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Example 1

The wrapping and wrapping steps of aluminum-stainless steel composite pipe hot isostatic pressing for the evaporator of a space vehicle thermal control system.

The evaporator is composed of aluminum-stainless steel composite tube assembly:

Aluminum alloy tube 7: the material is 3A21, the inner hole diameter is 10.6mm, the length is 140mm, and the outer diameter is larger than the maximum outer diameter of the special-shaped section of the composite pipe;

Stainless steel tube 9: the material is 316L, the outer diameter is 10mm, the inner hole size is M8×0.5mm, and the length is 150mm;

Transition metal layer 8: the material is PbIn5; the inner diameter is 10mm; the wall thickness is 0.25mm; the height is 10mm;

1. Hot isostatic pressing bag

1. Package structure

The package structure is shown in Figure 1. The components of the sheath in accompanying drawing 1 include: vacuum sheath shell 1, vacuum sheath first outer end cap 2, vacuum sheath first inner end cap 3, vacuum sheath second inner end cap 4, vacuum sheath second end cap Two outer end caps 5, vacuum bag exhaust pipe 6. The components of the composite pipe in the accompanying drawing 1 include: an aluminum alloy pipe 7, a transition metal layer 8, and a stainless steel pipe 9. There are 7 welds in the structure of accompanying drawing 1: the sheath shell and the first outer end cover are welded to form the first weld seam 10 of the vacuum envelope; the first outer end cover and the first inner end cover are welded to form the second weld of the vacuum envelope seam 11; the first inner end cover and the stainless steel pipe are welded to form the third weld seam 12 of the vacuum envelope; the envelope shell and the second outer end cover are welded to form the fourth weld seam 13 of the vacuum envelope; the second outer end cover and the second The fifth welding seam 14 of the vacuum envelope is formed by welding the inner end cover; the sixth weld seam 15 of the vacuum envelope is formed by welding the second inner end cover and the stainless steel pipe; the seventh weld seam 15 of the vacuum envelope is formed by welding the second outer end cover and the exhaust pipe of the envelope. Weld 16.

2. Material of package components

The sheath assembly consists of the vacuum sheath shell 1, the first outer end cap of the vacuum sheath 2, the first inner end cap 3 of the vacuum sheath, the second inner end cap 4 of the vacuum sheath, the second outer end cap of the vacuum sheath The end cap 5 and the vacuum sheath exhaust pipe 6 are composed. The material of the above components is copper (Cu), and the requirements are: the purity is greater than 99.9wt%, the oxygen content is less than 50ppm, and the wall thickness is 3.0mm.

3. Welding assembly tolerance

The assembly clearance of each component of the sheath and each component of the composite pipe is controlled within 0.1mm.

4. Pre-treatment of package components

① To remove oil, wipe the outer surface of oxygen-free copper parts with absorbent cotton dipped in gasoline, ultrasonically clean with metal degreaser, wash at 70°C for 45 minutes, rinse with tap water, then rinse with deionized water, and dehydrate with absolute ethanol;

②Chemical cleaning, solution composition: a mixed solution of concentrated sulfuric acid with a volume fraction of 5% and a saturated ferrous sulfate aqueous solution of 95%, the cleaning time is 5 minutes, and then neutralized with ammonia water with a mass fraction of 2% to 5%, and a large amount of tap water Rinse, rinse with deionized water, dehydrate with absolute ethanol;

③ Dehydration and drying at 60°C for 30 minutes;

④Heat treatment, hydrogen atmosphere, temperature is 600°C, treatment time is 3h, hydrogen dew point is -60°C;

5. Pretreatment of composite pipe components

①Clean with acetone;

② Dehydration with absolute ethanol;

③ Drying, the temperature is 60°C, and the drying time is 30 minutes;

④ Thermal vacuum degassing, the vacuum degree is 5.0×10 ^-3 Pa, the temperature is 280°C, and the degassing time is 3 hours.

6. Package assembly and welding

①The first inner end cap 3 of the vacuum sheath is assembled and welded with the stainless steel pipe 9 (the third welding seam 12 of the vacuum sheath), the second inner end cap 4 of the vacuum sheath is assembled and welded with the stainless steel pipe 9 (the sixth vacuum sheath Weld seam 15), the second outer end cover 5 of the vacuum sheath and the vacuum sheath exhaust pipe 6 are assembled and welded (the seventh weld seam 16 of the vacuum sheath). The welding process adopts vacuum brazing, the solder is AgCu28 solder, the welding temperature is 810°C to 820°C, the holding time is 5min, and the vacuum degree is better than 10 ^-3 Pa;

②The first inner end cap 3 of the vacuum sheath-stainless steel pipe 9-the weldment of the second inner end cap 4 of the vacuum sheath, the second outer end cap 5 of the vacuum sheath-the weldment of the exhaust pipe 6 of the vacuum sheath, the vacuum sheath Assembly of the first outer end cover 2, the vacuum sheath shell 1, the transition metal layer 8, and the aluminum alloy tube 7 (the first weld seam 10 of the vacuum sheath, the second weld seam 11 of the vacuum sheath, the fourth weld seam of the vacuum sheath seam 13, the fifth welding seam 14 of the vacuum sheath. The welding process adopts the electron beam welding method, and the penetration depth of the weld is required to be not less than 0.5mm;

7. Sheath thermal vacuum degassing

Thermal vacuum degassing process system: at a temperature of 280°C, the vacuum degree is better than 10 ^-3 Pa, and it is maintained for 3 hours;

8. Package sealing

After the thermal vacuum degassing of the sheath is completed, use pressure welding pliers to pinch off the vacuum sheath exhaust pipe 6 and weld the port.

2. Hot isostatic pressing

The hot isostatic pressing treatment is carried out on the composite pipe after vacuum wrapping. The process system is as follows: the temperature is 280°C, the pressure is 150MPa, and the heat preservation and pressure holding time is 2.5 hours.

3. The aluminum-stainless steel composite pipe formed by the hot isostatic pressure sheathing and sheathing process and the hot isostatic pressure diffusion welding achieves the following performance indicators:

(1) The straightness of the inner hole axis of the stainless steel tube 9 in the composite tube is better than 0.15/300mm;

(2) The metallurgical bonding rate of the composite pipe aluminum-stainless steel interface is greater than 95%, and the interface shear strength is greater than 20MPa;

(3) The composite pipe has passed the random mechanical vibration environment test. The test process refers to Q/W50.5A-2007 "Environmental Test Methods for Spacecraft Components Part 5: Vibration Test". There was no change in the appearance and bonding surface after the test.

(4) The composite pipe has passed the thermal cycle of high temperature 87°C and low temperature -60°C, high and low temperature storage test and thermal shock test of high temperature 265°C and low temperature 2°C. After the test, the appearance of the composite pipe remains unchanged, the interface bonding rate is greater than 95%, and the shear strength is greater than 20MPa.

Example 2

The wrapping and wrapping steps of hot isostatic pressing of aluminum and stainless steel composite pipes for the condenser of the thermal control system of a space vehicle.

The condenser is composed of composite tubes:

Stainless steel pipe 9: the material is 304, the outer diameter is 6mm, the wall thickness is 0.8mm, and the length is 280mm;

Transition metal layer 8: the material is Sn10Pb88Ag2; the inner diameter is 6mm; the wall thickness is 0.25mm; the height is 10mm;

Aluminum alloy tube 7: The material is 6063, the diameter of the inner hole is 6.6mm, the length is 270mm, and the diameter of the outer circle is larger than the maximum outer circle diameter of the special-shaped section of the composite pipe;

1. Hot isostatic pressing process

1. Package structure

The package structure is shown in Figure 1. The components of the sheath in accompanying drawing 1 include: vacuum sheath shell 1, vacuum sheath first outer end cap 2, vacuum sheath first inner end cap 3, vacuum sheath second inner end cap 4, vacuum sheath second end cap Two outer end caps 5, vacuum bag exhaust pipe 6. The components of the composite pipe in the accompanying drawing 1 include: an aluminum alloy pipe 7, a transition metal layer 8, and a stainless steel pipe 9. There are 7 welds in the structure of accompanying drawing 1: the sheath shell and the first outer end cover are welded to form the first weld seam 10 of the vacuum envelope; the first outer end cover and the first inner end cover are welded to form the second weld of the vacuum envelope seam 11; the first inner end cover and the stainless steel pipe are welded to form the third weld seam 12 of the vacuum envelope; the envelope shell and the second outer end cover are welded to form the fourth weld seam 13 of the vacuum envelope; the second outer end cover and the second The fifth welding seam 14 of the vacuum envelope is formed by welding the inner end cover; the sixth weld seam 15 of the vacuum envelope is formed by welding the second inner end cover and the stainless steel pipe; the seventh weld seam 15 of the vacuum envelope is formed by welding the second outer end cover and the exhaust pipe of the envelope. Weld 16.

2. Material of package components

The sheath assembly consists of the vacuum sheath shell 1, the first outer end cap of the vacuum sheath 2, the first inner end cap 3 of the vacuum sheath, the second inner end cap 4 of the vacuum sheath, the second outer end cap of the vacuum sheath The end cap 5 and the vacuum jacket exhaust pipe 6 are composed of copper (Cu) as the material of the above components, and the requirements are: the purity is greater than 99.9wt%, the oxygen content is less than 50ppm, and the wall thickness is 2.5mm.

3. Welding assembly tolerance

The assembly clearance of each component of the sheath and each component of the composite pipe is controlled within 0.10mm.

4. Pre-treatment of package components

① To remove oil, wipe the outer surface of oxygen-free copper parts with absorbent cotton dipped in gasoline, ultrasonically clean with metal degreaser, wash at 70°C for 45 minutes, rinse with tap water, then rinse with deionized water, and dehydrate with absolute ethanol;

②Chemical cleaning, solution composition: a mixed solution of 5% concentrated sulfuric acid and 95% saturated ferrous sulfate aqueous solution, cleaning time is 5 minutes, then neutralized with 2% to 5% ammonia water, rinsed with a large amount of tap water, deionized water Rinse, dehydrate with absolute ethanol;

③ Dehydration and drying at 60°C for 30 minutes;

④Heat treatment, hydrogen atmosphere, temperature is 600°C, time is 3h, hydrogen dew point is -60°C;

5. Pretreatment of composite pipe components

①Clean with acetone;

② Dehydration with absolute ethanol;

③ Drying at 60°C for 30 minutes;

④ Thermal vacuum degassing, the vacuum degree is 5.0×10 ^-3 Pa, the temperature is 230°C, and the degassing time is 3 hours.

6. Package assembly and welding

①The first inner end cap 3 of the vacuum sheath is assembled and welded with the stainless steel pipe 9 (the third welding seam 12 of the vacuum sheath), the second inner end cap 4 of the vacuum sheath is assembled and welded with the stainless steel pipe 9 (the sixth vacuum sheath Weld seam 15), the second outer end cover 5 of the vacuum sheath and the vacuum sheath exhaust pipe 6 are assembled and welded (the seventh weld seam 16 of the vacuum sheath). The welding process adopts vacuum brazing, the solder is AgCu28 solder, the welding temperature is 810°C to 820°C, the holding time is 5min, and the vacuum degree is better than 10 ^-3 Pa;

②The first inner end cap 3 of the vacuum sheath-stainless steel pipe 9-the weldment of the second inner end cap 4 of the vacuum sheath, the second outer end cap 5 of the vacuum sheath-the weldment of the exhaust pipe 6 of the vacuum sheath, the vacuum sheath Assembly of the first outer end cover 2, the vacuum sheath shell 1, the transition metal layer 8, and the aluminum alloy tube 7 (the first weld seam 10 of the vacuum sheath, the second weld seam 11 of the vacuum sheath, the fourth weld seam of the vacuum sheath seam 13, the fifth welding seam 14 of the vacuum sheath. The welding process adopts the electron beam welding method, and the penetration depth of the weld is required to be not less than 0.5mm;

7. Sheath thermal vacuum degassing

Thermal vacuum degassing process system: at a temperature of 230°C, the vacuum degree is better than 10 ^-3 Pa, and it is maintained for 3 hours;

8. Package sealing

After the thermal vacuum degassing of the sheath is completed, use pressure welding pliers to pinch off the vacuum sheath exhaust pipe 6 and weld the port.

2. Hot isostatic pressing

The hot isostatic pressing treatment is carried out on the composite pipe after vacuum wrapping. The process system is as follows: the temperature is 250°C, the pressure is 150MPa, and the heat preservation and pressure holding time is 2.5 hours.

3. The aluminum-stainless steel composite pipe formed by the hot isostatic pressure sheathing and sheathing process and the hot isostatic pressure diffusion welding achieves the following performance indicators:

(1) The straightness of the inner hole axis of composite pipe stainless steel pipe 9 is better than 0.15/300mm;

(2) The metallurgical bonding rate of the composite pipe aluminum-stainless steel interface is greater than 95%, and the interface shear strength is greater than 20MPa;

(3) The composite pipe has passed the random mechanical vibration environment test. The test process refers to Q/W50.5A-2007 "Environmental Test Methods for Spacecraft Components Part 5: Vibration Test". There was no change in the appearance and bonding surface after the test.

(4) The composite pipe has passed the thermal cycle of high temperature 87°C and low temperature -60°C, high and low temperature storage test and thermal shock test of high temperature 265°C and low temperature 2°C. After the test, the appearance of the composite pipe remains unchanged, the interface bonding rate is greater than 95%, and the shear strength is greater than 20MPa.

Claims (14)

1. the cladding method for the hip moulding of aluminum-stainless steel composite pipe, it is characterised in that specifically comprise the following steps that

1. jacket assembly is prepared; Described jacket assembly is made up of vacuum canning shell (1), vacuum canning the first outer end cap (2), vacuum canning the first inner end cap (3), vacuum canning the second inner end cap (4), vacuum canning the second outer end cap (5) and vacuum canning exhaust tube (6);

2. the assembling pre-treatment of jacket assembly and aluminum-stainless steel composite pipe assembly;

3. the assembling of jacket assembly and aluminum-stainless steel composite pipe assembly with weld;

When described jacket assembly and aluminum-stainless steel composite pipe assembly assembling, vacuum canning shell (1) is coated on aluminium-alloy pipe (7) outside; Inner layer stainless steel tube (9) two ends of described aluminum-stainless steel composite pipe are assembled with vacuum canning the first inner end cap (3) and vacuum canning the second inner end cap (4) respectively; Outer layer aluminium-alloy pipe (7) two ends of described aluminum-stainless steel composite pipe are assembled with vacuum canning the first outer end cap (2) and vacuum canning the second outer end cap (5) respectively; Described inner end cap is weldingly connected with adjacent outer end cap; Described outer end cap is weldingly connected with adjacent vacuum canning shell (1); Vacuum canning exhaust tube (6) and vacuum canning the second outer end cap (5) are weldingly connected; Described vacuum canning exhaust tube (6) communicates with the gap of jacket assembly and aluminum-stainless steel composite pipe assembly;

4. the degasification of gained jacket and sealing.

2. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 1, it is characterized in that: the material of described jacket assembly is copper or silver, the purity of described copper or silver is respectively greater than 99.9wt%, and oxygen content is not more than 50ppm respectively.

3. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 1, it is characterised in that: the wall thickness respectively 0.5mm to 5mm of the described each ingredient of jacket assembly.

4. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 1, it is characterised in that: the assembling pre-treating method of described jacket assembly is as follows: a. surface oxide layer is removed;B. oil removing is cleaned; C. dehydration, drying; D. annealing in hydrogen atmosphere processes or thermal vacuum degasification; E. protection is deposited.

5. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 4, it is characterized in that: the method that the annealing in hydrogen atmosphere of described jacket assembly process processes is: hydrogen atmosphere, treatment temperature is 350 DEG C～700 DEG C, the process time is 2～5 hours, and dew point of hydrogen is-80 DEG C～-40 DEG C; The thermal vacuum degasification method of described jacket assembly process is: be better than 5.0 × 10 in vacuum^-3When Pa, 350 DEG C～700 DEG C, degasification 2 to 5 hours.

6. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 1, it is characterised in that: the assembling pre-treating method of described aluminum-stainless steel composite pipe assembly is as follows: a. cleans oil removing; B. dehydration, drying; C. thermal vacuum degasification; D. protection is deposited.

7. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 6, it is characterised in that: the method for the thermal vacuum degasification of described aluminum-stainless steel composite pipe assembly process is: vacuum is better than 5.0 × 10^-3When Pa, 100 to 600 DEG C of degasification 2 to 5 hours.

8. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 1, it is characterized in that: described jacket assembly and aluminum-stainless steel composite pipe assembly are after assembling pre-treatment, fail in time assembling with when welding, needing to deposit under vacuum condition, the vacuum of storage environment is better than 100Pa.

9. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 1, it is characterised in that: described welding adopts the method for electron beam welding, plasma arc welding (PAW), argon arc welding, vacuum brazing or hydrogen shield soldering to complete; The weld penetration of wherein electron beam welding, plasma arc welding (PAW) and argon arc welding is all not less than 0.5mm, and the solder seam depth of cracking closure of vacuum brazing and hydrogen shield method for welding is all not less than 0.5mm.

10. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 9, it is characterised in that: high vacuum brazing materials selected by the solder of described vacuum brazing and hydrogen shield method for welding; Described high vacuum brazing materials are: AgCu, AgCuIn, AgCuPd, AgCuSn, AgCuNi, AuCu or AuNi system alloy material.

11. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 1, it is characterised in that: each several part gap between described jacket assembly and aluminum-stainless steel composite pipe assembly is no more than 0.10mm.

12. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 1, it is characterized in that: the degasification method of described jacket is: gained jacket connects air extractor by vacuum canning exhaust tube (6) after having welded, to carrying out thermal vacuum degasification in jacket.

13. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 12, it is characterised in that: described thermal vacuum degasification method is: under 100 to 600 degrees celsius, jacket vacuum is better than 10^-3Pa, maintains more than 2 hours.

14. the cladding method of a kind of hip moulding for aluminum-stainless steel composite pipe according to claim 1, it is characterized in that: the encapsulating method of described jacket is: after the degasification of jacket terminates, adopt press-welding pliers to vacuum canning exhaust tube (6) pinched-off seal weld port.