Aluminum alloy sheet for high-strength, high-toughness, and high-pressure hydrogen storage cylinder liner, preparation method, and gas cylinder liner

Abstract

An aluminum alloy sheet for a high-strength, high-toughness, and high-pressure hydrogen storage cylinder liner, a preparation method, and a gas cylinder liner. The chemical composition of said sheet in weight percentage is: Mg: 0.93-1.14%, Si: 0.56-0.70%, Fe: 0.45-0.51%, Cu: 0.29-0.33%, Mn: 0.01-0.03%, Cr: 0.17-0.23%, Zn: 0.01-0.07%, Ti: 0.028-0.033%, Pb: 0.001-0.003%, Bi: 0.0002-0.0006%, the remainder being Al and other inevitable impurities, with a total impurity content ≤ 0.15%, and the above elements further satisfying: Mg / Si = 1.6-1.68. The present invention, through alloy composition design and the use of a rolling thermal deformation method, improves grain size and the distribution of strengthening phases such as Mg2Si, Al2Cu, thereby enhancing the formability of the aluminum alloy sheet and obtaining a hydrogen storage cylinder liner having high strength, toughness, and fatigue life; moreover, the preparation process is shorter in duration and lower in costs, making it more suitable for industrial promotion and application.

Description

Aluminum alloy plate for high-strength and high-pressure hydrogen storage cylinder liner, preparation method and cylinder liner Technical Field

[0001] The present invention relates to the technical field of metal materials and processing thereof, and in particular to an aluminum alloy plate for a high-strength and high-pressure hydrogen storage cylinder liner, a preparation method and the cylinder liner. Background Art

[0002] As a clean, efficient, and sustainable new energy source, hydrogen has become a key component of a low-carbon energy system, boasting enormous market potential in the energy, transportation, and industrial sectors. The hydrogen energy use process primarily encompasses hydrogen production, storage, transportation, and application. The key to hydrogen energy application lies in safe and efficient hydrogen storage and transportation technologies.

[0003] Currently, hydrogen fuel is mostly stored in steel cylinders. However, these cylinders have drawbacks such as heavy weight, low volume-to-weight ratio, susceptibility to corrosion, unsafe failure modes, and low operating pressure, which restrict their application in new energy vehicles. In the context of promoting energy conservation and emission reduction, new energy vehicles urgently need a lightweight, high-pressure-resistant, and long-fatigue-life hydrogen storage cylinder component to overcome this bottleneck.

[0004] Therefore, in order to reduce weight, hydrogen storage containers with a metal liner fiber winding structure have appeared on the market. The metal liner material is usually aluminum alloy, but the high-strength and toughness aluminum alloys with grades such as 2xxx and 7xxx have weak spinning forming capabilities. There is an urgent need for an aluminum alloy material with strong forming capabilities and high strength and toughness to make the metal liner of the hydrogen storage container.

[0005] Chinese patent CN 112743878 A discloses a "fiber composite material high-pressure hydrogen storage cylinder and its preparation method." T700 carbon fiber is wrapped around the outer surface of a 6061 aluminum liner to enhance the strength and durability of the hydrogen cylinder, improving the performance and safety of the hydrogen cylinder for high-pressure hydrogen storage. Tested according to the GB / T35544-2017 standard, its final burst pressure value can reach over 170 MPa, and its fatigue loading life can reach over 10,000 times, which is consistent with the technical performance of the current mainstream Type III cylinder. The result is a high-pressure hydrogen storage cylinder that is lightweight, high-strength, fatigue-resistant, structurally rigid, and has good high and low temperature impact stability. However, the patent does not mention the relevant technology for the aluminum material required for the aluminum liner.

[0006] Chinese patent CN 115382984 A discloses "a stamping method and drawing die for large-volume hydrogen storage cylinder aluminum alloy liners." The method uses hot stamping of aluminum ingots, followed by turning, and finally cold drawing to produce the aluminum alloy liners for hydrogen storage cylinders without the need for forced spinning and thinning. This effectively solves the technical problem of low production efficiency of large-volume hydrogen storage cylinder aluminum alloy liners produced by forced spinning and thinning of aluminum tubes. However, the patent does not mention the relevant technology of the aluminum alloy used for the aluminum liners.

[0007] Chinese patent CN 115466887 A discloses "a high-strength and tough aluminum alloy liner material, preparation method, and application." By optimizing the aluminum alloy composition and employing processes such as semi-continuous casting, homogenization heat treatment, reverse extrusion forming, annealing heat treatment, high-pressure spinning, neck spinning, and solution aging heat treatment, a high-strength and tough aluminum alloy liner for high-pressure hydrogen cylinders is produced, significantly improving its mechanical properties. However, compared to rolling, reverse extrusion has the following disadvantages:

[0008] (1) Reverse extrusion molding requires the use of special equipment and molds for production, and its production cost is higher than that of roll forming;

[0009] (2) In the reverse extrusion process, since the material needs to be extruded through the die, the precision of the finished product is limited by the die, while the rolling process can improve the processing precision of the product through multiple rolling;

[0010] (3) Compared with rolling forming, in the process of reverse extrusion forming, the material is more likely to have defects such as indentations, scratches and pores, and needs to undergo surface treatment to achieve good surface quality.

[0011] Chinese patent CN 114457265 B discloses "a high-strength and high-fatigue performance 6-series aluminum alloy, a gas cylinder, and a preparation method thereof." By optimizing the alloy composition, increasing the maximum solid solution content of Mg2Si, and adding a homogenization heat treatment method, the base material grains after annealing are refined. The resulting gas cylinder has a tensile strength of more than 340 MPa after spray quenching at 550-560°C and aging treatment at 160-165°C, and the number of fatigue cycles can reach more than 16,000 times. However, this method has the following disadvantages: (1) This method adds a homogenization treatment process, which increases the cost for industrial production; (2) This method requires a cold rolling process, and the resulting plate has great limitations and can only be used for the production of small-sized gas cylinders, which is not conducive to industrial promotion and application.

[0012] In summary, the current method of strengthening the inner liner of hydrogen storage cylinders mainly considers the use of aluminum tube strong spinning and reverse extrusion. The only method of preparing aluminum alloy plates for hydrogen storage cylinders by rolling requires high-temperature and long-term homogenization heat treatment and cold rolling treatment. The scope of application is small and is not conducive to industrial promotion. Summary of the Invention

[0013] The object of the present invention is to provide a high-strength and tough aluminum alloy plate for high-pressure hydrogen storage cylinder liners, a preparation method and a cylinder liners. By improving the grain size of the aluminum alloy plate and the distribution of strengthening phases such as Mg2Si and Al2Cu, the formability of the aluminum alloy plate is improved. The yield strength of the aluminum alloy plate is ≤54MPa, the tensile strength is ≤120MPa, and the elongation is ≥29%, thereby obtaining a hydrogen storage cylinder liners with high strength and toughness and high fatigue life, the yield strength is ≥305MPa, the tensile strength is ≥336MPa, and the elongation is ≥12.5%; under the testing standard of GB / T35544, the burst strength is ≥144MPa, and the fatigue frequency is ≥14218 times; the aluminum alloy plate preparation method adopts rolling hot deformation, the process is short in time and low in cost, and is suitable for industrial application.

[0014] To achieve the above objectives, the technical solutions of the present invention are as follows:

[0015] In a first aspect, the present invention provides an aluminum alloy plate for a high-strength and tough high-pressure hydrogen storage cylinder liner. In addition to Al and inevitable impurities, the aluminum alloy plate further comprises the following chemical components in weight percentage: Mg: 0.93-1.14%, Si: 0.56-0.70%, Fe: 0.45-0.51%, Cu: 0.29-0.33%, Mn: 0.01-0.03%, Cr: 0.17-0.23%, Zn: 0.01-0.07%, Ti: 0.028-0.033%, Pb: 0.001-0.003%, Bi: 0.0002-0.0006%. The total amount of the inevitable impurities is ≤0.15%, and the above elements also need to satisfy: Mg / Si=1.6-1.68.

[0016] In one embodiment of the present invention, preferably, the aluminum alloy plate comprises the following components in weight percentage: Mg: 0.93-1.14%, Si: 0.56-0.70%, Fe: 0.45-0.51%, Cu: 0.29-0.33%, Mn: 0.01-0.03%, Cr: 0.17-0.23%, Zn: 0.01-0.07%, Ti: 0.028-0.033%, Pb: 0.001-0.003%, Bi: 0.0002-0.0006%, and the balance is Al and unavoidable impurities.

[0017] Preferably, the grain structure of the aluminum alloy plate of the present invention is fine equiaxed grains, and the average grain size is (148-259)±(17-68) μm.

[0018] It should be noted that the numerical range after the "±" sign refers to the difference between the largest and smallest grains in the plate. The smaller the numerical range, the smaller the difference in grain size and the more uniform the grain size distribution.

[0019] The aluminum alloy plate of the present invention has a yield strength of ≤54 MPa, a tensile strength of ≤120 MPa, and an elongation of ≥29%.

[0020] In the composition design of the present invention,

[0021] Mg can form a strengthening phase Mg2Si with Si to improve the strength of the alloy, but too high a content will reduce the toughness of the material. Therefore, the present invention controls the Mg element content to be 0.93-1.14%.

[0022] Si can increase strength, but too high a content may cause material corrosion. Therefore, the present invention controls the Si content to be 0.56-0.70%.

[0023] Cu can improve the strength and hardness of the material, but too high a content can also cause material corrosion. Therefore, the present invention controls the Cu content to be 0.29-0.33%.

[0024] Fe can generate inclusion substances when the pressure increases, thereby reducing the dissolution of the material in Al. Therefore, the Fe content is controlled within the range of 0.45-0.51% in the present invention.

[0025] Mn can be dissolved in aluminum alloys to hinder the occurrence of recrystallization. Too high a content will lead to severe intragranular segregation in the α phase, affecting the recrystallization process of the alloy and causing grain coarsening of the alloy in the annealed state. The present invention controls the Mn content to 0.01-0.03% to avoid grain coarsening caused by intragranular segregation.

[0026] Cr can increase material strength, control grain size, and provide toughness. Therefore, the present invention controls the Cr content to be 0.17-0.23%.

[0027] Zn can affect the grain size and corrosiveness, therefore, the present invention controls the Zn content to be 0.01-0.07%.

[0028] Ti can refine the grain structure, but too high a content will affect the ductility of the material. Therefore, the present invention controls the Ti content to be 0.028-0.033%.

[0029] Pb and Bi are harmful elements in gas cylinders and need to be strictly controlled. The present invention strictly controls the Pb content to be 0.001-0.003%, and strictly controls the Bi content to be 0.0002-0.0006%.

[0030] In terms of component design, the present invention controls the precipitation of strengthening phases such as Mg2Si and Al2Cu in the microstructure of the final gas cylinder made of the aluminum alloy plate through alloy composition design and further controlling Mg / Si=1.6-1.68. Among them, the Mg2Si phase accounts for 1.2-1.4 mol% of the total microstructure phase and has a size of 0.8-1.5 μm; the Al2Cu phase accounts for 0.2-0.3 mol% of the total microstructure phase and has a size of 50-80 nm, thereby improving the toughness and fatigue life of the gas cylinder liner. The yield strength and fatigue life of the gas cylinder liner are ≥305 MPa, the tensile strength is ≥336 MPa, and the elongation is ≥12.5%. Under the testing standard of GB / T 35544, the burst strength is ≥144 MPa, and the fatigue frequency of the gas cylinder is ≥14218 times, which far exceeds the requirements of 78.75 MPa and 11000 times for the hydrogen storage gas cylinder liner specified in GB / T 35544.

[0031] In a second aspect, the present invention provides a method for manufacturing the above-mentioned high-strength and high-pressure hydrogen storage cylinder liner aluminum alloy plate, comprising the following steps:

[0032] 1) Smelting and casting

[0033] Melting and casting are performed according to the above composition to obtain an ingot;

[0034] 2) Heating the ingot

[0035] Heating temperature: 420-500°C, heating time: 3-24h;

[0036] 3) Hot rolling

[0037] The hot rolled plate with a thickness of 12 to 30 mm is obtained by reversible hot rough rolling. The maximum pass reduction rate is controlled to be above 35% during the hot rough rolling process, and the hot rolling finishing temperature is controlled to be 240 to 280°C.

[0038] 4) Annealing

[0039] The annealing temperature is 390-450° C., the annealing time is 1-3 hours, and after the annealing is completed, the aluminum alloy plate is cooled to 200-260° C. at a cooling rate of 16-28° C. / h, and then taken out of the furnace and air-cooled to room temperature to obtain the aluminum alloy plate.

[0040] More specifically, "air cooling" refers to natural cooling in air, generally at a cooling rate of 30 to 50°C / h.

[0041] Preferably, in step 4), the thickness of the hot-rolled plate is 15 to 25 mm.

[0042] Preferably, in step 4), the annealing temperature is 410-430°C.

[0043] Preferably, in step 4), after annealing, the steel is cooled to 200-220° C. at a cooling rate of 18-22° C. / h.

[0044] The present invention optimizes the pass reduction during hot rolling to ensure that the maximum pass reduction is ≥35%, so that the fibrous structure in the aluminum alloy plate is fully broken and sufficient recrystallization nucleation cores are provided for the annealing process.

[0045] The hot rolling finishing temperature of the present invention is controlled at 240-280° C. By optimizing the finishing temperature during the hot rolling process, the release of stored energy during the hot rolling process is reduced, sufficient recrystallization driving force is provided for the subsequent annealing process, and the structure of the aluminum alloy is refined, so that the grain structure of the aluminum alloy plate is formed into fine equiaxed crystals with an average grain size of (148-259)±(17-68) μm.

[0046] After annealing, the aluminum alloy sheet of the present invention is cooled to 200-260°C at a cooling rate of 16-28°C / h. Due to the quenching effect, if the cooling rate is too fast after annealing, strengthening phases such as Mg2Si and Al2Cu will be produced prematurely during the annealing process, which is not conducive to the deep drawing of the sheet in the subsequent preparation of gas cylinders and reduces the alloy quenching effect during the heat treatment after deep drawing. Therefore, the present invention controls the cooling rate after annealing to 16-28°C / h.

[0047] In a third aspect, the present invention provides a high-strength, tough, and high-pressure hydrogen storage cylinder liner made from the above-mentioned aluminum alloy plate, wherein the microstructure of the hydrogen storage cylinder liner includes a Mg2Si phase and an Al2Cu phase; wherein the Mg2Si phase accounts for 1.2 to 1.4 mol% of the total microstructure phase and has a size of 0.8 to 1.5 μm, and the Al2Cu phase accounts for 0.2 to 0.3 mol% of the total microstructure phase and has a size of 50 to 80 nm.

[0048] Preferably, the yield strength of the hydrogen storage cylinder liner is ≥305MPa, the tensile strength is ≥336MPa, and the elongation is ≥12.5%; under the testing standard of GB / T 35544, its burst strength is ≥144MPa, and the fatigue frequency is ≥14218 times.

[0049] In a fourth aspect, the present invention provides a method for manufacturing the above-mentioned high-strength and high-pressure hydrogen storage cylinder liner, comprising the following steps:

[0050] 1) Gas cylinder molding

[0051] The aluminum alloy sheet is rounded to obtain a disc, the disc is oiled, cold drawn, the outer surface is polished, the lugs are cut, the end is spun, and the thread is made to obtain a preformed gas cylinder liner;

[0052] 2) T6 heat treatment

[0053] The obtained preformed gas cylinder liner is heated to 530-545°C for solution treatment within 40-80 minutes, and the solution treatment time is 40-80 minutes; after the solution treatment, it is cooled to room temperature with water and allowed to stand for 10-30 minutes; and then heated to 170-190°C within 30-60 minutes for aging treatment, and the aging time is 6-10 hours;

[0054] 3) Carbon fiber winding

[0055] The outer surface of the heat-treated gas cylinder liner is wrapped with carbon fiber to obtain a finished gas cylinder liner.

[0056] The aluminum alloy sheet obtained above is used to prepare the inner liner of a hydrogen storage cylinder. Since the aluminum alloy composition optimizes the composition range of Mg, Si, and Cu elements and further controls Mg / Si to be 1.6-1.68, the precipitation of Mg2Si and Al2Cu strengthening phases is controlled during the subsequent T6 heat treatment process, and the molar content of the Mg2Si phase in the microstructure of the final cylinder is controlled to be 1.2-1.4%, and the size is 0.8-1.5 μm, and the molar content of the Al2Cu phase is controlled to be 0.2-0.3%, and the size is 50-80 nm. As a result, the obtained inner liner has higher strength, thereby improving the blasting performance of the cylinder, with a yield strength of ≥305 MPa, a tensile strength of ≥336 MPa, and an elongation of ≥12.5%. Under the testing standard of GB / T35544, its blasting strength is ≥144 MPa, and the fatigue frequency is ≥14218 times.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] In terms of component design, the present invention controls the precipitation of strengthening phases such as Mg2Si and Al2Cu in the aluminum alloy plate during the subsequent T6 heat treatment through alloy composition design and further controlling Mg / Si=1.6-1.68, so that the molar content of the Mg2Si phase in the final gas cylinder microstructure is 1.2-1.4%, and the size is 0.8-1.5μm; the molar content of the Al2Cu phase is 0.2-0.3%, and the size is 50-80nm, thereby improving the toughness and fatigue life of the gas cylinder liner, with a yield strength of ≥305MPa, a tensile strength of ≥336MPa, and an elongation of ≥12.5%. Under the testing standard of GB / T35544, its burst strength is ≥144MPa, and the fatigue frequency is ≥14218 times, far exceeding the requirements of 78.75MPa and 11000 times for the hydrogen storage gas cylinder liner specified in GB / T35544.

[0059] Based on the composition design, the present invention optimizes the pass reduction during hot rolling to ensure a maximum pass reduction of 35% or more, fully breaking up the fibrous structure in the aluminum alloy sheet and providing sufficient recrystallization nucleation cores for the annealing process. The final rolling temperature during hot rolling is further optimized to 240-280°C, reducing the release of stored energy during hot rolling and providing sufficient driving force for recrystallization during annealing. Furthermore, by controlling the cooling rate and furnace temperature during annealing, the quenching effect of the alloy is reduced and the grain structure of the alloy is improved. This not only improves the formability of the aluminum alloy sheet, but also contributes to the subsequent improvement of the toughness and fatigue life of the gas cylinder liner. Furthermore, controlling the cooling rate during annealing prevents the premature precipitation of strengthening phases such as Mg2Si and Al2Cu during annealing, allowing them to precipitate after the subsequent T6 heat treatment. This improves the formability of the aluminum alloy sheet while ensuring the strength and toughness of the final gas cylinder.

[0060] The aluminum alloy sheet of the present invention is produced using a rolling hot deformation method, which avoids the need for prolonged heat treatment compared to traditional cold rolling processes. This method also expands the thickness specifications of aluminum alloy sheet for gas cylinder liners, enabling the production of larger gas cylinders. Compared to traditional aluminum alloy sheet thickness specifications of approximately 4 mm, the aluminum alloy sheet of the present invention can be produced in a range of 12-30 mm. This facilitates industrialization and application, and compared to traditional aluminum tube strong spinning and reverse extrusion methods, this method eliminates the need for specialized equipment and molds, enabling high-volume, low-cost production and further facilitating industrialization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] FIG1 is a metallographic photograph of the aluminum alloy plate according to Example 1 of the present invention.

[0062] FIG2 is a metallographic photograph of the aluminum alloy plate of Example 2 of the present invention.

[0063] FIG3 is a metallographic photograph of the aluminum alloy plate of Example 3 of the present invention.

[0064] FIG4 is a metallographic photograph of the aluminum alloy plate of Example 4 of the present invention.

[0065] FIG5 is a metallographic photograph of the aluminum alloy plate of Example 5 of the present invention.

[0066] FIG6 is a metallographic photograph of the aluminum alloy plate of Example 6 of the present invention.

[0067] FIG7 is a metallographic photograph of the aluminum alloy plate of Comparative Example 1 of the present invention.

[0068] FIG8 is a metallographic photograph of the aluminum alloy plate of Comparative Example 2 of the present invention.

[0069] FIG9 is a metallographic photograph of the aluminum alloy plate of Comparative Example 3 of the present invention.

[0070] FIG10 is a metallographic photograph of the aluminum alloy plate of Comparative Example 4 of the present invention.

[0071] FIG11 is a metallographic photograph of the aluminum alloy plate of Comparative Example 5 of the present invention.

[0072] FIG12 is a metallographic photograph of the aluminum alloy plate of Comparative Example 6 of the present invention. DETAILED DESCRIPTION

[0073] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0074] The compositions of the aluminum alloy plates of the embodiments of the present invention and the comparative examples are shown in Table 1, and the remainder of the compositions includes Al and other inevitable impurities.

[0075] The process parameters of the embodiments of the present invention and the comparative examples are shown in Table 2;

[0076] The mechanical properties and grain sizes of the aluminum alloy plates of the embodiments of the present invention and the comparative examples are shown in Table 3.

[0077] The aluminum alloy sheet obtained in the present invention is used to obtain the corresponding hydrogen storage cylinder liner according to the following steps:

[0078] 1) Gas cylinder molding

[0079] Aluminum alloy sheet rounding → round sheet oiling → cold drawing → outer surface grinding → cutting and ear making → spinning and closing → thread making to obtain preformed gas cylinder liner;

[0080] 2) T6 heat treatment

[0081] The obtained preformed gas cylinder liner is heated to 530-545°C for solution treatment within 40-80 minutes, and the solution treatment time is 40-80 minutes; after the solution treatment, it is cooled to room temperature with water and allowed to stand for 10-30 minutes; and then heated to 170-190°C within 30-60 minutes for aging treatment, and the aging time is 6-10 hours;

[0082] 3) Carbon fiber winding

[0083] The outer surface of the heat-treated gas cylinder liner is wrapped with carbon fiber to obtain a finished gas cylinder liner.

[0084] The contents and sizes of Mg2Si and Al2Cu contained in the gas cylinder liner tissues prepared from the aluminum alloy plates of the embodiments of the present invention and the comparative examples are shown in Table 4.

[0085] The mechanical properties, bursting strength, and fatigue frequency of the gas cylinder liners prepared from the aluminum alloy plates of the embodiments of the present invention and the comparative examples are shown in Table 5, with GB / T 35544 as the testing standard.

[0086] In Example 1, samples were taken to test the grain structure and mechanical properties of the aluminum alloy plate after annealing. The mechanical properties are shown in Table 3. Figure 1 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Example 1 of the present invention. It can be seen from the photograph that the grain structure is composed of equiaxed crystals, the average grain size is 148±17μm, and there are only slight differences between the grain sizes. The mechanical properties of the inner liner at room temperature were tested by sampling, and the yield strength was 310MPa, the tensile strength was 343MPa, and the elongation was 12.5%. The bursting strength of the inner liner of the obtained hydrogen storage cylinder can reach 150MPa, meeting the bursting performance requirement of ≥78.75MPa in GB / T 35544, and the fatigue frequency can reach 17131 times, meeting the fatigue performance requirement of ≥11000 times in GB / T 35544.

[0087] In Example 2, samples were taken to test the grain structure and mechanical properties of the aluminum alloy plate after annealing. The mechanical properties are shown in Table 3. Figure 2 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Example 2 of the present invention. As can be seen from the photograph, the grain structure is composed of equiaxed crystals with an average grain size of 237±46μm. The mechanical properties of the gas cylinder liner prepared using the same at room temperature are as follows: its yield strength is 308MPa, its tensile strength is 341MPa, and its elongation is 13.2%. The burst strength of the hydrogen storage gas cylinder liner obtained can reach 146MPa, meeting the burst performance requirement of ≥78.75MPa in GB / T 35544, and its fatigue frequency can reach 14314 times, meeting the fatigue performance requirement of ≥11000 times in GB / T 35544.

[0088] In Example 3, samples were taken to test the grain structure and mechanical properties of the aluminum alloy plate after annealing. The mechanical properties are shown in Table 3. Figure 3 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Example 3 of the present invention. As can be seen from the photograph, the grain structure is composed of equiaxed crystals with an average grain size of 232±68μm. The mechanical properties of the gas cylinder liner prepared using the same at room temperature are as follows: its yield strength is 305MPa, its tensile strength is 338MPa, and its elongation is 12.8%. The burst strength of the hydrogen storage gas cylinder liner obtained can reach 144MPa, meeting the burst performance requirement of ≥78.75MPa in GB / T 35544, and its fatigue frequency can reach 14532 times, meeting the fatigue performance requirement of ≥11000 times in GB / T 35544.

[0089] In Example 4, samples were taken to test the grain structure and mechanical properties of the aluminum alloy plate after annealing. The mechanical properties are shown in Table 3. Figure 4 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Example 4 of the present invention. As can be seen from the photograph, the grain structure is composed of equiaxed crystals with an average grain size of 203±43μm. The mechanical properties of the gas cylinder liner prepared using the same at room temperature are as follows: its yield strength is 306MPa, its tensile strength is 336MPa, and its elongation is 12.7%. The burst strength of the hydrogen storage gas cylinder liner obtained can reach 145MPa, meeting the burst performance requirement of ≥78.75MPa in GB / T 35544, and its fatigue frequency can reach 15135 times, meeting the fatigue performance requirement of ≥11000 times in GB / T 35544.

[0090] In Example 5, samples were taken to test the grain structure and mechanical properties of the aluminum alloy plate after annealing. The mechanical properties are shown in Table 3. Figure 5 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Example 5 of the present invention. As can be seen from the photograph, the grain structure is composed of equiaxed crystals with an average grain size of 204±38μm. The mechanical properties of the gas cylinder liner prepared using the present invention at room temperature are as follows: its yield strength is 309MPa, its tensile strength is 339MPa, and its elongation is 12.6%. The burst strength of the hydrogen storage gas cylinder liner obtained can reach 148MPa, meeting the burst performance requirement of ≥78.75MPa in GB / T 35544, and its fatigue frequency can reach 15157 times, meeting the fatigue performance requirement of ≥11000 times in GB / T 35544.

[0091] In Example 6, samples were taken to test the grain structure and mechanical properties of the aluminum alloy plate after annealing. The mechanical properties are shown in Table 3. Figure 6 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Example 6 of the present invention. It can be seen from the photograph that the grain structure is composed of equiaxed crystals with an average grain size of 259±66μm. The mechanical properties of the gas cylinder liner prepared using the same at room temperature are as follows: its yield strength is 308MPa, its tensile strength is 340MPa, and its elongation is 12.5%. The burst strength of the hydrogen storage gas cylinder liner obtained can reach 147MPa, meeting the burst performance requirement of ≥78.75MPa in GB / T 35544, and its fatigue frequency can reach 14218 times, meeting the fatigue performance requirement of ≥11000 times in GB / T 35544.

[0092] In Comparative Example 1, samples were taken to test the grain structure and mechanical properties of the aluminum alloy plate after annealing. The mechanical properties are shown in Table 3. Figure 7 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Comparative Example 1 of the present invention. It can be seen from the photograph that the average grain size is 361±141μm, the grain size is coarse, and the difference between the grain sizes is large. The mechanical properties of the gas cylinder liner prepared using it at room temperature are as follows: its yield strength is 270MPa, its tensile strength is 316MPa, and its elongation is 15.4%. The amount and particle size of the Mg2Si and Al2Cu strengthening phases in the microstructure of the obtained hydrogen storage gas cylinder liner do not meet the requirements of the present invention. Its burst strength is only 120MPa, and its fatigue frequency is only 12619 times.

[0093] In Comparative Example 2, samples were taken to test the grain structure and mechanical properties of the aluminum alloy sheet after annealing. The mechanical properties are shown in Table 3. Figure 8 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Comparative Example 2 of the present invention. It can be seen from the photograph that the average grain size is 445±159μm, the grain size is coarse, and the difference between the grain sizes is large. The mechanical properties of the gas cylinder liner prepared using it at room temperature are as follows: its yield strength is 308MPa, its tensile strength is 339MPa, and its elongation is 12.9%. The burst strength of the hydrogen storage gas cylinder liner obtained is 143MPa. Although it can reach the same level as the present invention, its fatigue frequency is lower, only 11318 times.

[0094] In comparative example 3, samples were taken to test the grain structure and mechanical properties of the aluminum alloy plate after annealing. The mechanical properties are shown in Table 3. Figure 9 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of comparative example 3 of the present invention. It can be seen from the photograph that the average grain size is 549±245μm, the grain size is coarse and the difference between the grain sizes is large. The mechanical properties of the gas cylinder liner prepared using it at room temperature are as follows: the yield strength is 307MPa, the tensile strength is 336MPa, and the elongation is 13.1%. The burst strength of the hydrogen storage gas cylinder liner obtained is 144MPa. The fatigue frequency of the hydrogen storage gas cylinder liner obtained is only 9532 times, which does not meet the fatigue performance requirement of ≥11000 times in GB / T 35544.

[0095] In comparative example 4, samples were taken to test the grain structure and mechanical properties of the aluminum alloy plate after annealing. The mechanical properties are shown in Table 3. Figure 10 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of comparative example 4 of the present invention. It can be seen from the photograph that the average grain size is 479±244μm, the grain size is coarse and the difference between the grain sizes is large. The mechanical properties of the gas cylinder liner prepared using it at room temperature are as follows: its yield strength is 272MPa, its tensile strength is 315MPa, and its elongation is 13.5%. The burst strength of the hydrogen storage gas cylinder liner obtained is relatively low, at 123MPa. Its fatigue frequency is only 9613 times, which does not meet the fatigue performance requirement of ≥11000 times in GB / T 35544.

[0096] In Comparative Example 5, samples were taken to test the grain structure and mechanical properties of the aluminum alloy sheet after annealing. The mechanical properties are shown in Table 3. Figure 11 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Comparative Example 5 of the present invention. It can be seen from the photograph that the average grain size is 427±124μm, the grain size is coarse, and the difference between the grain sizes is large. The mechanical properties of the gas cylinder liner prepared using it at room temperature are as follows: its yield strength is 309MPa, its tensile strength is 338MPa, and its elongation is 12.4%. The burst strength of the hydrogen storage gas cylinder liner obtained is 143MPa, but its fatigue frequency is relatively low, only 11639 times.

[0097] In Comparative Example 6, samples were taken to test the grain structure and mechanical properties of the aluminum alloy sheet after annealing. The mechanical properties are shown in Table 3. Figure 12 is a metallographic structure photograph of the rolled surface of the aluminum alloy sample of Comparative Example 6 of the present invention. As can be seen from the photograph, the average grain size is 435±151μm, the grain size is coarse, and the difference between the grain sizes is large. The mechanical properties of the gas cylinder liner prepared using the same were tested at room temperature, and its yield strength was 273MPa, the tensile strength was 317MPa, and the elongation was 12.7%. The obtained hydrogen storage gas cylinder liner had a low burst strength of 125MPa and a low fatigue frequency of only 11103 times.

Claims

1. An aluminum alloy plate for a hydrogen storage cylinder liner, characterized in that: In addition to Al and inevitable impurities, the aluminum alloy plate also contains the following chemical components in weight percentage: Mg: 0.93-1.14%, Si: 0.56-0.70%, Fe: 0.45-0.51%, Cu: 0.29-0.33%, Mn: 0.01-0.03%, Cr: 0.17-0.23%, Zn: 0.01-0.07%, Ti: 0.028-0.033%, Pb: 0.001-0.003%, Bi: 0.0002-0.0006%, the total amount of the inevitable impurities is ≤0.15%, and the above elements also need to satisfy: Mg / Si=1.6-1.

68.

2. The aluminum alloy plate for the inner liner of the hydrogen storage cylinder according to claim 1, characterized in that: The aluminum alloy plate comprises the following components in weight percentage: Mg: 0.93-1.14%, Si: 0.56-0.70%, Fe: 0.45-0.51%, Cu: 0.29-0.33%, Mn: 0.01-0.03%, Cr: 0.17-0.23%, Zn: 0.01-0.07%, Ti: 0.028-0.033%, Pb: 0.001-0.003%, Bi: 0.0002-0.0006%, and the balance is Al and unavoidable impurities.

3. The aluminum alloy plate for the inner liner of a hydrogen storage cylinder according to claim 1 or 2, characterized in that: The grain structure of the aluminum alloy plate is equiaxed grain, and the average grain size is (148-259)±(17-68) μm.

4. The aluminum alloy plate for the inner liner of a hydrogen storage cylinder according to claim 1 or 2, characterized in that: The thickness of the aluminum alloy plate is 12-30 mm.

5. The aluminum alloy plate for the inner liner of a hydrogen storage cylinder according to claim 1 or 2, characterized in that: The yield strength of the aluminum alloy plate is ≤54 MPa, the tensile strength is ≤120 MPa, and the elongation is ≥29%.

6. A method for manufacturing the aluminum alloy plate for the inner liner of a hydrogen storage cylinder according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: 1) Smelting and casting Melting and casting the composition according to claim 1 or 2 to obtain an ingot; 2) Heating the ingot Heating temperature: 420-500°C, heating time: 2-24h; 3) Hot rolling The hot rolled plate with a thickness of 12 to 30 mm is obtained by reversible hot rough rolling, wherein the maximum pass reduction is controlled to be above 35% during the hot rough rolling process, and the hot rolling finishing temperature is controlled to be 240 to 280°C; 4) Annealing The annealing temperature is 390-450° C., the annealing time is 1-3 hours, and after the annealing is completed, the aluminum alloy plate is cooled to 200-260° C. at a cooling rate of 16-28° C. / h, and then taken out of the furnace and air-cooled to room temperature to obtain the aluminum alloy plate.

7. The manufacturing method according to claim 6, wherein: In step 3), the thickness of the hot-rolled plate is 15 to 25 mm.

8. The manufacturing method according to claim 6, wherein: In step 4), the annealing temperature is 410-430°C.

9. The manufacturing method according to claim 6, wherein: In step 4), after annealing, the temperature is cooled to 200-220° C. at a cooling rate of 18-22° C. / h.

10. A hydrogen storage cylinder liner made from the aluminum alloy sheet according to any one of claims 1 to 5, characterized in that: The microstructure of the hydrogen storage cylinder liner includes Mg2Si phase and Al2Cu phase; wherein the Mg2Si phase accounts for 1.2-1.4 mol% of the total microstructure phase and has a size of 0.8-1.5 μm, and the Al2Cu phase accounts for 0.2-0.3 mol% of the total microstructure phase and has a size of 50-80 nm.

11. The hydrogen storage cylinder liner according to claim 10, characterized in that: The yield strength of the hydrogen storage cylinder liner is ≥305MPa, the tensile strength is ≥336MPa, and the elongation is ≥12.5%; under the testing standard of GB / T35544, its burst strength is ≥144MPa, and the fatigue frequency is ≥14218 times.

12. A method for manufacturing a hydrogen storage cylinder liner according to claim 10 or 11, characterized in that: The method comprises the following steps: 1) Gas cylinder molding The aluminum alloy sheet is rounded to obtain a disc, the disc is oiled, cold drawn, the outer surface is polished, the ears are cut, the end is spun, and the thread is made to obtain a preformed gas cylinder liner; 2) T6 heat treatment The obtained preformed gas cylinder liner is heated to 530-545°C for solution treatment within 40-80 minutes, and the solution treatment time is 40-80 minutes; after the solution treatment, it is cooled to room temperature with water and allowed to stand for 10-30 minutes; and then heated to 170-190°C within 30-60 minutes for aging treatment, and the aging time is 6-10 hours; 3) Carbon fiber winding The outer surface of the heat-treated gas cylinder liner is wrapped with carbon fiber to obtain a finished gas cylinder liner.

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