Preparation Method of Ultra-Low Temperature High-Toughness Airbag Tube

Abstract

The present invention discloses a preparation method of an extremely low-temperature high-toughness airbag tube. The steps of the method include: S1: Classify Co powder, Cr powder and Ni powder with different particle sizes and uniformly mix them according to non-equiatomic ratios. Then, perform high-energy ball milling on the mixed powder obtained after mixing in a high-energy ball mill to obtain CoCrNi alloy powder. Then, mix the CoCrNi alloy powder with paraffin, dry it and granulate it; S2: Add the particles obtained by granulation in step S1 into an injection molding machine and inject them into a mold through the injection molding machine. After cooling and solidifying, a tube blank is formed; S3: Perform hot pressing on the obtained tube blank in a hot isostatic pressing furnace to obtain an airbag tube. Then, place the airbag tube in a vacuum heating furnace for homogenization treatment, and then perform quenching treatment. The present invention can enable the prepared airbag tube to have high tensile strength and good low-temperature toughness under extremely low-temperature conditions, so that the airbag tube can withstand the high pressure generated instantaneously during inflation and thus avoid causing secondary harm to the human body.

Description

Technical Field

[0001] The present invention relates to the technical field of airbag tubes, and in particular to a preparation method of an extremely low temperature and high toughness airbag tube. Background Art

[0002] Currently, airbag systems are used to deploy airbags with gas during a vehicle collision to buffer and protect between passengers and the vehicle, thereby reducing the harm suffered by passengers. Among them, the steel pipes for airbags need to withstand a large pressure instantaneously during inflation. However, most of the existing steel pipes for airbags have an obvious ductile-brittle transition phenomenon, and the toughness of the existing steel pipes for airbags is poor in an extremely low temperature environment (-196°C to -80°C), making it difficult to withstand the high pressure generated instantaneously during inflation, and thus secondary disasters will occur, endangering the safety of passengers.

[0003] For example, the Chinese patent application with the application number CN200480013485.2 discloses a steel pipe for an airbag system and its manufacturing method. In this method, a steel pipe is obtained by making a pipe and cold working on steel with specific components, and then the steel pipe is subjected to processes such as heating, quenching, and tempering, so that the steel pipe obtains a tensile strength of 1000 MPa and high toughness with a ductile fracture surface at -40°C. However, it still cannot meet the toughness requirements of the airbag tube in an extremely low temperature environment (-196°C to -80°C).

[0004] Again, for example, the Chinese patent application with the application number CN201180037798.1 discloses a manufacturing method of a steel pipe for an airbag. In this method, the steel pipe has a high tensile strength of more than 900 MPa and excellent low temperature toughness below -60°C through processes such as cold drawing and heat treatment on seamless steel pipes. However, this steel pipe still cannot meet the toughness requirements of the airbag tube in an extremely low temperature environment (-196°C to -80°C), and the tensile strength is not high enough. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a preparation method of an extremely low temperature and high toughness airbag tube, which can enable the prepared airbag tube to have a high tensile strength and good low temperature toughness under extremely low temperature conditions (-196°C to -80°C), so that the airbag tube can withstand the high pressure generated instantaneously during inflation and thus avoid causing secondary harm to the human body.

[0006] To solve the above technical problem, the technical solution of the present invention is: a preparation method of an extremely low temperature and high toughness airbag tube, and the steps of the method include:

[0007] S1: Preparation of CoCrNi alloy powder. Classify Co powder, Cr powder and Ni powder with different particle sizes and uniformly mix them according to non-equiatomic ratios. Then, subject the obtained mixed powder to high-energy ball milling in a high-energy ball mill to obtain CoCrNi alloy powder. After that, mix the CoCrNi alloy powder with paraffin, dry it and granulate it.

[0008] S2: Tube blank injection molding. Add the particles obtained by granulation in step S1 into an injection molding machine and inject them into a mold through the injection molding machine. After cooling and solidifying, a tube blank is formed.

[0009] S3: Hot forming of the airbag tube. Subject the obtained tube blank to hot pressing in a hot isostatic pressing furnace to obtain an airbag tube. Then, place the airbag tube in a vacuum heating furnace for homogenization treatment, and then perform quenching treatment.

[0010] S4: Stress relief treatment. Subject the quenched airbag tube to stress relief annealing in a vacuum heating furnace.

[0011] S5: Surface treatment. Sandblast the inner and outer surfaces of the stress-relieved airbag tube.

[0012] Furthermore, in step S1, the particle size of Co powder is 100 - 160 µm, the particle size of Cr powder is 50 - 80 µm, the particle size of Ni powder is 25 - 40 µm, and the purity of Co powder, Cr powder and Ni powder all reaches 99.99%.

[0013] Furthermore, in step S1, the atomic percentages of Co powder, Cr powder and Ni powder are 30%: (70 - x)%: x%; where the range of x is 5 - 20.

[0014] Furthermore, in step S1, when the mixed powder is subjected to high-energy ball milling in a high-energy ball mill, the high-energy ball milling medium is agate grinding balls, the ball-to-material ratio is 10:1, the ball milling duration is 24 h, the ball milling additive is alcohol, the ball milling speed is 300 r / min, and the particle size of the obtained CoCrNi alloy powder is 15 - 45 µm.

[0015] Furthermore, in step S1, the CoCrNi alloy powder and paraffin are prepared and mixed according to a mass ratio of 5:1, dried in an oven at 50 °C, and the particle size of the granulated particles is 25 - 55 µm.

[0016] Furthermore, a specific step of step S2 is provided. The specific step of step S2 is as follows:

[0017] Add the particles obtained by granulation in step S1 into the hopper of the injection molding machine, plasticize the particles by heating through the injection barrel heater in the injection molding machine, and then inject the paste in a semi-solid state plasticized by the screw into the mold. After cooling and solidifying, a tube blank is formed.

[0018] Furthermore, the heating temperature of the syringe heater is 100~120°C;

[0019] The injection speed of the semi-solid paste by the screw into the mold is 3~4 m / s, and the injection pressure is 10~20 MPa;

[0020] The cooling temperature for forming the tube blank after cooling and solidification is 30~60°C.

[0021] Furthermore, the specific parameters in step S3 are provided. In step S3, the heating temperature in the hot isostatic pressing furnace is 1200~1400°C, and the pressure is 200 MPa;

[0022] The temperature for homogenization treatment in the vacuum heating furnace is 1000°C, and the duration of homogenization treatment is 2 h;

[0023] The quenching medium for quenching treatment is an aqueous sodium chloride solution.

[0024] Furthermore, the specific parameters in step S4 are provided. In step S4, the temperature for stress relief annealing treatment is 500°C, and the duration of stress relief annealing treatment is 2 h.

[0025] Furthermore, the specific parameters in step S5 are provided. In step S5, silicon carbide is used for sandblasting, and the sandblasting distance is 30 mm.

[0026] Compared with the prior art, the airbag tube prepared by the method of the present invention is a non-equiatomic CoCrNi airbag tube, which uses a non-equiatomic ternary medium-entropy alloy. By adjusting the atomic percentage of elements, the stacking fault energy of the alloy is regulated. The low stacking fault energy is beneficial to activating a variety of plastic deformation mechanisms, improving the low-temperature toughness of the material, and solving the problem of low-temperature brittle fracture of the airbag tube in the prior art. Specifically, the phase of the airbag tube prepared by this method is a single-phase FCC structure, and the grains are equiaxed grains. Under extremely low temperature (-196°C to -80°C) conditions, the stacking fault energy is between -3 and 5 J / m 2 ², and dislocation, twin, and martensitic phase transformation deformation mechanisms will be simultaneously activated inside the grains. The fracture of the alloy is mainly a ductile fracture mechanism of micropore aggregation. Furthermore, it can enable the airbag tube to have high tensile strength, good low-temperature toughness and low-temperature bursting performance, large elongation, and low-temperature impact absorption work under extremely low temperature (-196°C to -80°C) conditions, making the mechanical properties of the airbag tube more stable. Furthermore, it enables the airbag tube to withstand the high pressure generated during inflation, thereby avoiding secondary injury to the human body caused by the low-temperature brittleness of the airbag tube. It is measured that under the temperature condition of -196°C, the tensile strength of the airbag tube prepared by the method of the present invention is ≥1005 Mpa, the elongation is ≥25%, the impact work is ≥28 J, and the impact toughness value is ≥7 J / cm 2 .

[0027] In addition, in step S2, the metal injection molding is realized by an injection molding machine to prepare the tube blank, which not only improves the production efficiency, saves materials, but also solves the problem of complex plastic forming process of the airbag tube in the prior art. In step S3, the hot isostatic pressing technology is used for hot pressing to obtain the airbag tube, which can obtain a fine-grained organizational structure, improve the strength of the airbag tube, and solve the problems of coarse grains and low comprehensive mechanical properties of the current as-cast airbag tube. The stress relief annealing treatment in step S4 can eliminate internal defects and residual internal stresses, while the sandblasting treatment in step S5 can remove the oxide scale on the inner and outer surfaces of the airbag tube and make the inner and outer surfaces obtain residual compressive stresses, thereby reducing the crack propagation caused by surface defects and solving the problem of surface cracking caused by surface defects generated in the cold forming process of the airbag tube in the prior art. Description of the Drawings

[0028] Figure 1 It is a TEM image of the microstructure of the cryogenic high-strength and tough airbag tube prepared by using the method of the present invention;

[0029] Figure 2 It is a graph showing the relationship between the impact energy and the atomic percentage of Ni element of the airbag tubes prepared in Examples 1-5 of the present invention;

[0030] Figure 3 It is a graph showing the relationship between the impact toughness value and the atomic percentage of Ni element of the airbag tubes prepared in Examples 1-5 of the present invention;

[0031] Figure 4 It is a graph showing the relationship between the tensile strength and the atomic percentage of Ni element of the airbag tubes prepared in Examples 1-5 of the present invention;

[0032] Figure 5 It is a graph showing the relationship between the elongation and the atomic percentage of Ni element of the airbag tubes prepared in Examples 1-5 of the present invention. Detailed Embodiments

[0033] The present invention provides a method for preparing a cryogenic high-strength and tough airbag tube. Those skilled in the art can draw on the content of this article and appropriately improve the process parameters to implement it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they all belong to the scope of protection of the present invention. The method and application of the present invention have been described through preferred embodiments, and those skilled in the art can obviously make changes or appropriate changes and combinations to the methods and applications in this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0034] The present invention provides a method for preparing a cryogenic high-strength and tough airbag tube. The steps of the method include:

[0035] S1: Preparation of CoCrNi alloy powder. Co powder, Cr powder and Ni powder with different particle sizes are classified and uniformly mixed according to non-equiatomic ratio. Then the mixed powder obtained is subjected to high-energy ball milling in a high-energy ball mill to obtain CoCrNi alloy powder. Then the CoCrNi alloy powder is mixed with paraffin, dried and granulated. Among them, granulation can be completed through processes such as microwave drying, crushing and sieving by existing equipment.

[0036] S2: Tube blank injection molding. The particles obtained by granulation in step S1 are added to an injection molding machine and injected into a mold through the injection molding machine. After cooling and solidifying, a tube blank is formed.

[0037] S3: Hot forming of the airbag tube. The obtained tube blank is hot-pressed and formed in a hot isostatic pressing furnace to obtain an airbag tube. Then the airbag tube is homogenized in a vacuum heating furnace and then quenched.

[0038] S4: Stress relief treatment. The airbag tube after quenching is subjected to stress relief annealing in a vacuum heating furnace to eliminate internal defects and residual internal stresses.

[0039] S5: Surface treatment. The inner and outer surfaces of the stress-relieved airbag tube are sandblasted. Sandblasting can remove the oxide scale on the inner and outer surfaces of the airbag tube and make the inner and outer surfaces obtain residual compressive stresses, thereby being able to reduce the crack propagation caused by surface defects and solve the problem of surface cracking caused by surface defects generated in the cold forming process of the airbag tube in the prior art.

[0040] Specifically, in step S2, metal injection molding is realized through an injection molding machine to prepare the tube blank, which not only improves production efficiency, saves materials, but also solves the problem of complex plastic forming process of the airbag tube in the prior art.

[0041] Specifically, in step S3, hot isostatic pressing technology is used for hot pressing and forming to obtain an airbag tube, which can obtain a fine-grained microstructure, improve the strength of the airbag tube, and solve the problems of coarse grains and low comprehensive mechanical properties of the current as-cast airbag tube. In this embodiment, the grain size of the airbag tube after hot isostatic pressing is 30 - 80 µm.

[0042] The airbag tube prepared by this method is a non-equiatomic ratio CoCrNi airbag tube, which uses a ternary medium-entropy alloy with a non-equiatomic ratio. By adjusting the atomic percentage of elements, the stacking fault energy of the alloy is regulated. A low stacking fault energy is beneficial to activating various plastic deformation mechanisms, improving the low-temperature toughness of the material, and solving the problem of low-temperature brittle fracture of the airbag tube in the prior art. Specifically, the phase of the airbag tube prepared by this method is a single-phase FCC structure, and the grains are equiaxed grains. Under extremely low temperature (-196°C to -80°C) conditions, the stacking fault energy is between -3 and 5 J / m 2 ². Inside the grains, dislocation, twin, and martensitic phase transformation deformation mechanisms will be simultaneously activated. The fracture of the alloy is mainly a ductile fracture mechanism of micropore aggregation. Therefore, the airbag tube can have high tensile strength, good low-temperature toughness and low-temperature bursting performance, large elongation, and low-temperature impact absorption work under extremely low temperature (-196°C to -80°C) conditions, making the mechanical properties of the airbag tube more stable. Furthermore, the airbag tube can withstand the high pressure generated during inflation, thus avoiding secondary harm to the human body caused by the low-temperature brittleness of the airbag tube. Specifically, after testing at a temperature of -196°C, the tensile strength of the airbag tube prepared by the method of the present invention is ≥1005 Mpa, the elongation is ≥25%, the impact work is ≥28 J, and the impact toughness value is ≥7 J / cm 2 .

[0043] In this embodiment, the Co powder, Cr powder, and Ni powder are all elemental powders.

[0044] Furthermore, in step S1, the particle size of the Co powder is 100 - 160 µm, the particle size of the Cr powder is 50 - 80 µm, the particle size of the Ni powder is 25 - 40 µm, and the purity of the Co powder, Cr powder, and Ni powder all reaches 99.99%.

[0045] The atomic percentages of the Co powder, Cr powder, and Ni powder are 30%:(70 - x)%:x%; where the range of x is 5 - 20.

[0046] When the mixed powder is high-energy ball milled in a high-energy ball mill, the high-energy ball milling medium is agate grinding balls, the ball-to-powder ratio is 10:1, the ball milling duration is 24 h, the ball milling additive is alcohol, the ball milling speed is 300 r / min, and the particle size of the CoCrNi alloy powder obtained after ball milling is 15 - 45 µm. Specifically, the ball diameter of the agate grinding balls is 6 mm, that is, the mixed powder is high-energy ball milled in the high-energy ball mill with agate grinding balls with a ball diameter of 6 mm in industrial alcohol at a rotation speed of 300 r / min for 24 h. Among them, the ball-to-powder ratio is the mass ratio of the agate grinding balls to the mixed powder.

[0047] Furthermore, in step S1, the CoCrNi alloy powder and paraffin are mixed in a mass ratio of 5:1 and dried in an oven at 50°C to obtain particles with a particle size of 25 - 55 µm.

[0048] Further provide a specific operation of step S2. The specific steps of step S2 are as follows:

[0049] Add the particles obtained by granulation in step S1 into the hopper of the injection molding machine. After heating by the injection barrel heater in the injection molding machine, the particles are plasticized, and then the plasticized semi-solid paste is injected into the mold through the screw. After cooling and solidifying, a tube blank is formed. Specifically, the injection molding machine has components such as a hopper, an injection barrel heater, and a screw. The specific structure of the injection molding machine is the prior art well-known to those skilled in the art and will not be specifically described in this embodiment.

[0050] Furthermore, the heating temperature of the injection barrel heater is 100 - 120 °C; the injection speed of the screw injecting the semi-solid paste into the mold is 3 - 4 m / s, and the injection pressure is 10 - 20 MPa; the cooling temperature for forming the tube blank after cooling and solidifying is 30 - 60 °C.

[0051] Furthermore, in step S3, the heating temperature in the hot isostatic pressing furnace is 1200 - 1400 °C, and the pressure is 200 MPa; the temperature for homogenization treatment in the vacuum heating furnace is 1000 °C, and the duration of homogenization treatment is 2 h; the quenching medium for quenching treatment is an aqueous sodium chloride solution.

[0052] Furthermore, in step S4, the temperature for stress relief annealing treatment is 500 °C, and the duration of stress relief annealing treatment is 2 h. In step S5, the abrasive blasting treatment uses emery, and the abrasive blasting distance is 30 mm.

[0053] In order to make the content of the present invention easier to be clearly understood, the following further elaborates on the present invention according to specific embodiments.

[0054] Example 1:

[0055] A method for preparing an extremely low-temperature high-strength and tough airbag tube, the steps of the method include:

[0056] S1: Preparation of CoCrNi alloy powder. Mix Co powder, Cr powder and Ni powder evenly according to the atomic percentage of 30%: 66%: 4%. Among them, Co powder, Cr powder and Ni powder are all elemental powders with a purity of 99.99%. The particle size of Co powder is 100 - 160 µm, the particle size of Cr powder is 50 - 80 µm, and the particle size of Ni powder is 25 - 40 µm. Then put the mixed powder obtained into a high-energy ball mill, add industrial alcohol to the high-energy ball mill and add agate grinding balls with a diameter of 6 mm according to a ball-to-material ratio of 10:1. Use agate grinding balls with a diameter of 6 mm to perform high-energy ball milling in industrial alcohol at a rotation speed of 300 r / min for 24 h to obtain CoCrNi alloy powder with a particle size of 15 - 45 µm. Then mix the CoCrNi alloy powder and paraffin according to a mass ratio of 5:1, and dry it in an oven at 50 °C and then granulate it.

[0057] S2: Tube blank injection molding. Add the particles obtained by granulation in step S1 into the hopper of an injection molding machine, heat the particles to 120 °C through the injection barrel heater in the injection molding machine to plasticize the particles, and then inject the plasticized semi-solid paste into the mold at an injection speed of 4 m / s and an injection pressure of 20 MPa through a screw. Wait until it cools to 30 °C and solidifies to form a tube blank.

[0058] S3: Hot forming of the airbag tube. Perform hot pressing on the obtained tube blank in a hot isostatic pressing furnace at a temperature of 1400 °C and a pressure of 200 MPa to obtain an airbag tube. Then place the airbag tube in a vacuum heating furnace for homogenization treatment at a temperature of 1000 °C for 2 h, and then perform quenching treatment in an aqueous sodium chloride solution.

[0059] S4: Stress relief treatment. Perform stress relief annealing treatment on the airbag tube after quenching treatment in a vacuum heating furnace at a temperature of 500 °C for 2 h.

[0060] S5: Surface treatment. Sandblast the inner and outer surfaces of the stress-relieved airbag tube with emery, and the sandblasting distance is 30 mm.

[0061] Use the following test methods to test the airbag tube prepared in this embodiment and list the measured impact work values, impact toughness values, tensile strength, elongation and burst resistance performance in Table 1. The specific methods are as follows:

[0062] Test method for impact energy and impact toughness value: Take an arc-shaped impact specimen with dimensions of 2mm * 10mm * 55mm from the wall thickness direction of the prepared airbag tube, and make a standard U-shaped notch with a depth of 2mm on the arc-shaped impact specimen. Place the arc-shaped impact specimen in a low-temperature tank filled with liquid nitrogen (melting point -196°C, applicable to test temperature ≥ -196°C) for heat preservation for 10 - 15 minutes, then take out the arc-shaped impact specimen from the low-temperature tank and quickly place it in a pendulum impact machine for impact testing, thereby obtaining the impact energy value and impact toughness value of the airbag tube, and list the test results in Table 1.

[0063] Test method for tensile strength and elongation: Take a tensile specimen of national standard with dimensions of 2mm * 10mm * 33mm from the prepared airbag tube. Place the tensile specimen in a low-temperature tank filled with liquid nitrogen (melting point -196°C, applicable to test temperature ≥ -196°C) for heat preservation for 10 - 15 minutes, then take out the tensile specimen from the low-temperature tank and quickly place it on a tensile testing machine for tensile testing, thereby obtaining the tensile strength and elongation of the airbag tube, and list the test results in Table 1.

[0064] Test method for burst resistance: Cut a 250mm long burst tube from the prepared airbag tube and weld and seal both ends of the burst tube, leaving a φ4 threaded hole at one end to connect with the tank truck supercharger. Inject -196°C liquid nitrogen in the tank truck supercharger into the burst tube under pressure through a cryogenic pump to cause the burst tube to burst. The burst resistance is evaluated by whether the crack extends to any end of the burst tube, and list the test results in Table 1.

[0065] Example 2:

[0066] The preparation method of this example is basically the same as that of the ultra-low temperature high toughness airbag tube in Example 1, and the difference from Example 1 is only that: in step S1 of this example, Co powder, Cr powder and Ni powder are uniformly mixed according to the atomic percentage of 30%: 62%: 8%.

[0067] Use the test method described in Example 1 to test the airbag tube prepared in this example, and list the measured impact energy value, impact toughness value, tensile strength, elongation and burst resistance in Table 1.

[0068] Example 3:

[0069] The preparation method of this example is basically the same as that of the ultra-low temperature high toughness airbag tube in Example 1, and the difference from Example 1 is only that: in step S1 of this example, Co powder, Cr powder and Ni powder are uniformly mixed according to the atomic percentage of 30%: 58%: 12%.

[0070] The airbag tube prepared in this example was tested using the test method described in Example 1, and the measured impact work value, impact toughness value, tensile strength, elongation, and burst resistance performance were listed in Table 1.

[0071] Example 4:

[0072] The preparation method of this example is basically the same as that of the ultra-low temperature and high toughness airbag tube in Example 1, and the difference from Example 1 is only that: in step S1 of this example, Co powder, Cr powder, and Ni powder are uniformly mixed according to the atomic percentages of 30%:54%:16%.

[0073] The airbag tube prepared in this example was tested using the test method described in Example 1, and the measured impact work value, impact toughness value, tensile strength, elongation, and burst resistance performance were listed in Table 1.

[0074] Example 5:

[0075] The preparation method of this example is basically the same as that of the ultra-low temperature and high toughness airbag tube in Example 1, and the difference from Example 1 is only that: in step S1 of this example, Co powder, Cr powder, and Ni powder are uniformly mixed according to the atomic percentages of 30%:50%:20%.

[0076] The airbag tube prepared in this example was tested using the test method described in Example 1, and the measured impact work value, impact toughness value, tensile strength, elongation, and burst resistance performance were listed in Table 1.

[0077] Example 6:

[0078] The preparation method of this example is basically the same as that of the ultra-low temperature and high toughness airbag tube in Example 1, and the difference from Example 1 is only that: in step S2 of this example, the particles obtained by granulation in step S1 are added to the hopper of the injection molding machine, and the particles are heated to 100 °C by the injection barrel heater in the injection molding machine to plasticize the particles, and then the plasticized semi-solid paste is injected into the mold at an injection speed of 3 m / s and an injection pressure of 10 MPa through the screw. After cooling to 45 °C, it solidifies and forms a tube blank. In step S3 of this example, the obtained tube blank is hot-pressed and formed in a hot isostatic pressing furnace at a temperature of 1200 °C and a pressure of 200 MPa to obtain an airbag tube, and then the airbag tube is placed in a vacuum heating furnace for homogenization treatment at a temperature of 1000 °C for 2 h, and then quenched in an aqueous sodium chloride solution.

[0079] The airbag tube prepared in this example was tested using the test method described in Example 1, and the measured impact work value, impact toughness value, tensile strength, elongation, and burst resistance performance were listed in Table 1.

[0080] Example 7:

[0081] The preparation method of this example is basically the same as that of the ultra-low temperature tough airbag tube in Example 1. The difference from Example 1 is only that: in step S2 of this example, the particles obtained by granulation in step S1 are added to the hopper of the injection molding machine, and the particles are heated to 110 °C by the injection barrel heater in the injection molding machine to make the particles plasticized, and then the plasticized semi-solid paste is injected into the mold at an injection speed of 3.5 m / s and an injection pressure of 15 MPa through the screw. When it is cooled to 60 °C, it solidifies and forms a tube blank. In step S3 of this example, the obtained tube blank is hot-pressed and formed in a hot isostatic pressing furnace at a temperature of 1300 °C and a pressure of 200 MPa to obtain an airbag tube, and then the airbag tube is placed in a vacuum heating furnace for homogenization treatment at a temperature of 1000 °C for 2 h, and then quenching treatment is carried out in an aqueous sodium chloride solution.

[0082] The airbag tube prepared in this example was tested using the test method described in Example 1, and the measured impact work value, impact toughness value, tensile strength, elongation, and burst resistance performance were listed in Table 1.

[0083] Comparative Example 1

[0084] The preparation method of this comparative example is basically the same as that of the ultra-low temperature tough airbag tube in Example 1. The difference from Example 1 is only that: in step S1 of this comparative example, Co powder, Cr powder, and Ni powder are uniformly mixed according to the atomic percentage of 30%: 40%: 30%.

[0085] The airbag tube prepared in this comparative example was tested using the test method described in Example 1, and the measured impact work value, impact toughness value, tensile strength, elongation, and burst resistance performance were listed in Table 1.

[0086] Comparative Example 2

[0087] An existing airbag tube was purchased on the market, and the purchased airbag tube was tested using the test method described in Example 1, and the measured impact work value, impact toughness value, tensile strength, elongation, and burst resistance performance were listed in Table 1.

[0088] Table 1

[0089] <![CDATA[Impact energy A k (J)]]> <![CDATA[Impact toughness value a k (J / cm 2 )]]> Tensile strength (MPa) Elongation at break (%) Blasting resistance Example 1 38 9.5 1231 35% 1 Example 2 35 8.75 1203 30% 1 Example 3 29 7.25 1100 27% 1 Example 4 28 7 1005 25% 1 Example 5 28 7 1005 25% 1 Example 6 36 9 1215 33% 1 Example 7 37 9.25 1223 31% 1 Comparative example 1 12 3 512 18% 2 Comparative example 2 8 2 389 12% 2

[0090] Note: In the column of burst resistance performance, 1 indicates that the liquid burst at -196°C is a ductile fracture and no crack penetrates to any end face of the burst pipe; 2 indicates that the liquid burst at -196°C is a brittle fracture and there is a crack penetrating to a certain end face of the burst pipe.

[0091] As can be seen from the above table, the airbag tubes in Examples 1 to 7 use the atomic percentages of chemical elements specified in the technical solution of the present invention and are produced according to the preparation method provided by the present invention. The airbag tubes in Examples 1 to 7 have a tensile strength ≥1005 Mpa, an elongation ≥25%, an impact energy ≥28 J, and an impact toughness value ≥7 J / cm in an extremely low temperature environment (-196°C to -80°C). 2 Moreover, after the liquid burst at -196°C, it shows a ductile fracture surface and the crack does not penetrate to any end face of the burst pipe.

[0092] The specific embodiments described above further elaborate on the technical problems solved, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of an extremely low-temperature and high-toughness airbag tube, characterized in that, the steps of the method include: S1: Preparation of CoCrNi alloy powder. Co powder, Cr powder and Ni powder with different particle sizes are classified and uniformly mixed according to non-equiatomic ratios, and the mixed powder obtained after mixing is subjected to high-energy ball milling in a high-energy ball mill to obtain CoCrNi alloy powder. Then, the CoCrNi alloy powder is mixed with paraffin, dried and granulated; S2: Injection molding of the tube blank. The particles obtained by granulation in step S1 are added to an injection molding machine and injected into a mold through the injection molding machine. After cooling and solidifying, a tube blank is formed; S3: Hot forming of the airbag tube. The obtained tube blank is subjected to hot pressing in a hot isostatic pressing furnace to obtain an airbag tube. Then, the airbag tube is placed in a vacuum heating furnace for homogenization treatment, and then quenching treatment is carried out; S4: Stress relief treatment. The airbag tube after quenching treatment is subjected to stress relief annealing in a vacuum heating furnace; S5: Surface treatment. The inner and outer surfaces of the stress-relieved airbag tube are sandblasted; wherein, in step S1, the particle size of Co powder is 100~160 µm, the particle size of Cr powder is 50~80 µm, the particle size of Ni powder is 25~40 µm, and the purity of Co powder, Cr powder and Ni powder all reaches 99.99%; wherein, in step S1, the atomic percentages of Co powder, Cr powder and Ni powder are 30%: (70 - x)%: x%; wherein, the range of x is 5~20; wherein, in step S1, when the mixed powder is subjected to high-energy ball milling in a high-energy ball mill, the high-energy ball milling medium is agate grinding balls, the ball-to-material ratio is 10:1, the ball milling duration is 24 h, the ball milling additive is alcohol, the ball milling speed is 300 r / min, and the particle size of the CoCrNi alloy powder obtained after ball milling is 15~45 µm; wherein, in step S1, the CoCrNi alloy powder and paraffin are prepared and mixed according to a mass ratio of 5:1, dried in an oven at 50 °C, and the particle size of the granulated particles is 25~55 µm; wherein, in step S3, the heating temperature in the hot isostatic pressing furnace is 1200~1400 °C, and the pressure is 200 MPa; the temperature for homogenization treatment in the vacuum heating furnace is 1000 °C, and the duration of homogenization treatment is 2 h; the quenching medium for quenching treatment is an aqueous sodium chloride solution.

2. The preparation method of the extremely low-temperature and high-toughness airbag tube according to claim 1, characterized in that, the specific steps of step S2 are: The particles obtained by granulation in step S1 are added to the hopper of an injection molding machine, plasticized by heating with an injection cylinder heater in the injection molding machine, and then the semi-solid paste is injected into a mold through a screw. After cooling and solidifying, a tube blank is formed.

3. The preparation method of the extremely low-temperature and high-toughness airbag tube according to claim 2, characterized in that, the heating temperature of the injection cylinder heater is 100~120 °C; the injection speed of the screw injecting the semi-solid paste into the mold is 3~4 m / s, and the injection pressure is 10~20 MPa; the cooling temperature for forming a tube blank after cooling and solidifying is 30~60 °C.

4. The preparation method of the cryogenic high-toughness airbag tube according to claim 1, characterized in that, in step S4, the temperature of the stress relief annealing treatment is 500 °C, and the duration of the stress relief annealing treatment is 2 h.

5. The preparation method of the cryogenic high-toughness airbag tube according to claim 1, characterized in that, in step S5, the sandblasting treatment uses carborundum, and the sandblasting distance is 30 mm.

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