Aluminum alloy strip and preparation method thereof

Abstract

The invention discloses an aluminum alloy strip and a preparation method thereof. The preparation method comprises the following steps: preparing a cast ingot according to a raw material formula; the cast ingot is subjected to saw cutting and surface milling in sequence; carrying out heating treatment on the cast ingot subjected to surface milling; carrying out hot rolling on the cast ingot subjected to the heating treatment to obtain a hot-rolled blank; annealing the hot-rolled blank for the first time; performing cold rolling on the hot-rolled blank subjected to the first annealing to obtain a cold-rolled coil; the cold-rolled coil is subjected to secondary annealing, and an aluminum alloy strip is obtained; the performance of the aluminum alloy strip is in a H22-H24 state, and the earing rate of the aluminum alloy strip is 2.0-3.5%. The aluminum alloy strip obtained through the preparation method is free of U-shaped lines after deep drawing, the surface is fine and smooth and good in brightness after anodic oxidation, and when the aluminum alloy strip serves as a material of an electronic cigarette shell, the aluminum alloy strip is free of U-shaped lines after deep drawing and good in anodic effect, and the appearance of the electronic cigarette shell cannot be affected.

Description

[Technical field]

[0001] The invention relates to the technical field of aluminum processing, and in particular to an aluminum alloy strip and a preparation method thereof. [Background technology]

[0002] Smoking is harmful and has no benefits. It not only affects the health and life of smokers, but also pollutes the air and harms others. Electronic cigarettes have a positive effect on smokers’ quitting smoking. The main reason is that tobacco contains nicotine and electronic cigarettes can adjust the nicotine content according to personal needs, so as to help smokers gradually reduce their dependence on nicotine.

[0003] Compared with the smoke produced by traditional cigarettes, the smoke produced by electronic cigarettes is more environmentally friendly and more friendly to passive smokers around them. As people attach great importance to health, the use of electronic cigarettes is becoming wider and wider, and the grades are also increasing. The requirements for aluminum alloy as the material of electronic cigarette shells are also repeatedly improved.

[0004] Most of the aluminum alloys used for electronic cigarette shells are obtained by homogenizing ingots, extruding and aging. The electronic cigarette shells obtained by extrusion have the disadvantages of uneven organizational properties, low production efficiency, large waste loss, low yield and high cost.

[0005] Related technologies In order to solve the above shortcomings, soft alloy materials such as the 1st series, 6063, and 6061 are widely used as electronic cigarette shell materials for deep drawing. However, they have obvious U-shaped patterns after deep drawing, which cannot be covered even after sandblasting and oxidation, and the anode effect is poor, which seriously affects their overall appearance. [Summary of the invention]

[0006] The purpose of the embodiment of the present invention is to provide an aluminum alloy strip and a preparation method thereof, so as to solve the problem that the aluminum alloy used as the shell material of the electronic cigarette in the related art has obvious U-shaped lines after deep drawing, cannot be covered after sandblasting and oxidation, has poor anode effect, and seriously affects its overall appearance.

[0007] In a first aspect, an embodiment of the present invention provides a method for preparing an aluminum alloy strip, comprising the following steps:

[0008] Step S1, preparing an ingot according to a raw material formula;

[0009] Step S2, sawing and milling the ingot in sequence;

[0010] Step S3, heating the milled ingot; the temperature of the ingot during the heating treatment is 490±15° C., and the heating treatment time is 4 to 8 hours;

[0011] Step S4, hot rolling the ingot after the heating treatment to obtain a hot-rolled billet with a thickness of 8 to 9 mm; the hot rolling is carried out by a hot rolling mill, and the final rolling temperature of the hot rolling is 320 to 340° C. Before the hot rolling mill is used, a brush mark test is performed on the rollers of the hot rolling mill, and the brush mark width of the rollers of the hot rolling mill is 28 to 30 mm, and the thickness of the aluminum adhesion layer of the rollers of the hot rolling mill is 10 to 15 μm; when the hot rolling mill is used, the temperature of the F3 roller of the hot rolling mill is greater than 80° C.

[0012] Step S5, performing a first annealing on the hot-rolled billet; the temperature of the first annealing is 500±15° C., and the time of the first annealing is 3 to 6 hours;

[0013] Step S6, cold rolling the hot-rolled billet after the first annealing to obtain a cold-rolled coil with a thickness of 2.0 mm; the cold rolling reduction rate is 70-85%; and the rolling is performed in four passes, the roughness Ra of the rollers used in the first and second passes is 0.40±0.02μm, and the RPc is 100-200, and the roughness Ra of the rollers used in the third and fourth passes is 0.25±0.02μm, and the RPc is 130-150;

[0014] Step S7, performing a second annealing on the cold-rolled coil to obtain an aluminum alloy strip; the performance of the aluminum alloy strip is in the H22-H24 state, and the earing rate of the aluminum alloy strip is 2.0-3.5%.

[0015] Preferably, in step S1, the components and mass percentages of the raw material formula are: Mg=0.7-0.9wt%, Si=0.5-0.6wt%, Fe≤0.10wt%, Mn≤0.02wt%, Cr≤0.03wt%, and the balance is Al.

[0016] Preferably, in step S1, preparing the ingot according to the raw material formula includes the following sub-steps:

[0017] S11, selecting aluminum ingots whose mass percentages of elements Mg, Si, Fe, Mn, Cr, and Al meet the raw material formula as a melt and putting them into a smelting furnace for smelting to obtain aluminum liquid;

[0018] S12, performing a first refining on the aluminum liquid; the first refining adopts a particle refining agent and argon powder spraying refining, and the first refining time is 20 to 25 minutes;

[0019] S13, transferring the aluminum liquid after the first refining into a holding furnace for a second refining; the second refining adopts a granular refining agent and argon powder spraying refining, and the second refining time is 30 to 35 minutes;

[0020] S14, deslagging the aluminum liquid after the second refining and letting it stand for 60 to 120 minutes;

[0021] S15, degassing the aluminum liquid after standing by using a degassing box, wherein the oxygen content in the degassing box is less than 0.12 mL / 100 gAl, and the degassing box uses a first-grade aluminum titanium boron wire to add a grain refiner online during the degassing process;

[0022] S16, using a filter box to filter the degassed aluminum liquid; the filtered aluminum liquid is cast through a crystallizer to obtain the ingot.

[0023] Preferably, in step S6, the rollers used in the third and fourth rolling passes are reversely ground before use, and the roughness Ra of the rollers after 10 rolling passes is ensured to be less than 0.25 μm.

[0024] Preferably, in step S7, the recrystallization ratio of the aluminum alloy strip is 50-80%.

[0025] In a second aspect, an embodiment of the present invention provides an aluminum alloy strip, which is made by the above-mentioned method for preparing an aluminum alloy strip, and the aluminum alloy strip is used to make a shell of an electronic cigarette.

[0026] Compared with the related art, the aluminum alloy strip in the present invention is prepared by preparing ingots, sawing and milling the ingots, heating the ingots, hot rolling the ingots, cold rolling the hot-rolled billets after the first annealing, annealing the cold-rolled coils, and limiting the parameters of the heating treatment, hot rolling, the first annealing, cold rolling and the aluminum alloy strip, so as to obtain an aluminum alloy strip with no U-shaped lines after deep drawing and a fine surface and good brightness after anodizing. When the aluminum alloy strip is used as the material of an electronic cigarette shell, it can be made without U-shaped lines after deep drawing, with good anode effect, and will not affect the appearance of the electronic cigarette shell.

Brief Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0028] Figure 1 A schematic flow chart of the steps of a method for preparing an aluminum alloy strip provided in Embodiment 1 of the present invention;

[0029] Figure 2 A comparison diagram of the preparation method and results of the aluminum alloy in the related art and the aluminum alloy strip in Example 1 of the present invention;

[0030] Figure 3 This is a crystal state diagram of the hot-rolled billet provided in Example 1 of the present invention after being magnified 200 times;

[0031] Figure 4 This is a crystal state diagram of the hot-rolled billet provided in Example 1 of the present invention after the first annealing and magnified 200 times.

[0032] Figure 5 This is a crystal state diagram of the aluminum alloy strip provided in Example 1 of the present invention after being magnified 200 times;

[0033] Figure 6 This is a schematic diagram comparing the U-shaped patterns of aluminum alloy after deep drawing. [Specific implementation method]

[0034] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1

[0036] The embodiment of the present invention provides a method for preparing an aluminum alloy strip, Figure 1 As shown, the following steps:

[0037] S1. Prepare ingots according to the raw material formula.

[0038] The components and mass percentages of the raw material formula are as follows: Mg = 0.7-0.9wt%, Si = 0.5-0.6wt%, Fe ≤ 0.10wt%, Mn ≤ 0.02wt%, Cr ≤ 0.03wt%, and the balance is Al. This limitation can ensure that the obtained aluminum alloy strip has excellent stamping performance and has a full and bright color after anodizing.

[0039] A high content of Mg can improve the strengthening effect of aluminum alloy, a high content of Si can improve the fluidity of aluminum alloy stamping, and Fe, Mn, and Cr as impurity elements can control the grain size and coarse grain layer of aluminum alloy, but a high content will make the color of aluminum alloy after anode darker, affecting the anode effect; after many tests, while ensuring that the grain and anode effect of aluminum alloy are excellent, it is best to limit Fe≤0.1wt%, Mn≤0.02wt%, and Cr≤0.03wt%.

[0040] The preparation of ingots according to the raw material formula includes the following sub-steps:

[0041] S11. Aluminum ingots containing the elements Mg, Si, Fe, Mn, Cr and Al in a mass percentage that meets the raw material formula are selected as a melt and placed in a smelting furnace for smelting to obtain aluminum liquid.

[0042] S12, performing a first refining on the aluminum liquid; the first refining adopts a particle refining agent and argon powder spraying refining, and the time of the first refining is 20 to 25 minutes.

[0043] S13, transferring the aluminum liquid after the first refining into a holding furnace for a second refining; the second refining adopts a granular refining agent and argon powder spraying refining, and the time of the second refining is 30 to 35 minutes.

[0044] Among them, the second refining uses granular refining agent and argon gas to spray powder and refine the recycled waste aluminum liquid.

[0045] S14, the aluminum liquid after the second refining is deslagging and left to stand for 60 to 120 minutes.

[0046] S15. Degassing the aluminum liquid after standing by using a degassing box, wherein the oxygen content in the degassing box is less than 0.12 mL / 100 gAl, and the degassing box uses first-grade aluminum titanium boron wire (AlTi5B1) to add grain refiner online during the degassing process.

[0047] S16, using a filter box to filter the degassed aluminum liquid; the filtered aluminum liquid is cast through a crystallizer to obtain the ingot.

[0048] Wherein, the filter box includes a coarse filtration part and a fine filtration part; the coarse filtration part includes a 40-mesh ceramic filter plate and a small deep bed, and the fine filtration part includes a large deep bed; the degassed aluminum liquid is firstly subjected to a coarse filtration through a 40-mesh ceramic filter plate and a small deep bed, and then subjected to fine filtration through a large deep bed.

[0049] S2. sawing and milling the ingot in sequence.

[0050] S3, heating the ingot after surface milling.

[0051] Wherein, the temperature of the ingot during the heating treatment is 490±15°C, and the heating treatment time is 4 to 8 hours.

[0052] S4. Hot rolling the ingot after the heating treatment to obtain a hot-rolled billet with a thickness of 8 to 9 mm.

[0053] Wherein, the hot rolling is carried out by a hot rolling mill, and the final rolling temperature of the hot rolling is 320-340°C; before the hot rolling mill is used, a brush mark test is performed on the rollers of the hot rolling mill, and the brush mark width of the rollers of the hot rolling mill is made to be 28-30 mm, and the thickness of the aluminum bonding layer of the rollers of the hot rolling mill is 10-15 μm; when the hot rolling mill is used, the temperature of the F3 roller of the hot rolling mill is greater than 80°C.

[0054] The definition of the brush mark test can ensure that the surface texture of the hot-rolled billet obtained is fine and the oxidation effect is good.

[0055] The grain state of the hot-rolled billet before the first annealing is magnified 200 times as shown in the figure. Figure 3 shown.

[0056] S5. Performing a first annealing on the hot-rolled billet.

[0057] Among them, the hot-rolled billet of normal deep drawing is directly rolled into the finished product, and then annealed to the O state. The U-shaped pattern is serious after deep drawing and cannot be covered after sandblasting. Figure 2 Scheme 1 in this embodiment. By limiting the first annealing temperature to 500±15℃ and the first annealing time to 3-6h, the fiber strip grains of the hot-rolled billet can form completely recrystallized grains, and the grain size of 50-200μm accounts for more than 80%, providing a basis for changing the O state of the cold-rolled coil to the H22-H24 state, such as Figure 4 shown.

[0058] S6. Cold rolling the hot-rolled billet after the first annealing to obtain a cold-rolled coil with a thickness of 2.0 mm.

[0059] Among them, the cold rolling reduction rate is 70-85%, preferably 77.8%; and the rolling is carried out in four passes, the roughness Ra (average roughness) of the rollers used in the first and second passes is 0.40±0.02μm, RPc (roughness peak count) is 100-200, and the roughness Ra of the rollers used in the third and fourth passes is 0.25±0.02μm, RPc is 130-150.

[0060] If the roughness of the rolling roller in cold rolling is Ra0.40μm, the U-shaped pattern of the cold-rolled coil obtained after deep drawing is obvious; and this embodiment limits the rolling rollers used in the third and fourth rolling passes to reverse grinding before use, and ensures that the roughness Ra of the rolling rollers after 10 rolling passes is less than 0.25μm, thereby improving the surface roughness of the rolling rollers to ensure a fine surface of the aluminum alloy, and reducing the generation of U-shaped patterns after deep drawing.

[0061] S7, performing a second annealing on the cold-rolled coil to obtain an aluminum alloy strip.

[0062] The temperature of the second annealing is about 290° C., and the time of the second annealing is set according to actual needs.

[0063] The normal final rolling temperature of 6 series aluminum alloy is 300-320℃, the thickness of hot rolled billet is 4-6mm, when the finished aluminum alloy with a thickness of 2.0 is rolled, the earing rate is 6.51-8.1%, and the U-shaped pattern is serious after deep drawing, such as Figure 2 Solution 1 in the figure. For deep-drawn aluminum alloy, there are ears at 0° and 90°, but no ears in the rolling direction. In this embodiment, by limiting the hot rolling final temperature to 320-340°C and the thickness of the hot-rolled billet to 8-9 mm, the earing rate of the aluminum alloy strip can be controlled to 2.0-3.5%. On the one hand, the aluminum alloy strip can be subjected to uniform force during stamping, and the generation of U-shaped lines can be reduced after deep drawing. On the other hand, the stamping qualification rate can be improved.

[0064] The deep-drawn aluminum alloy is in a completely recrystallized state with O material. After deep-drawing, the U-shaped pattern is serious, such as Figure 2 In the scheme 1, or the H12 / 14 state, the yield point is high, and it is easy to crack after deep drawing and cannot be formed. After the second annealing in this application, the performance of the aluminum alloy strip is H22~H24 state, the yield point is higher than the deformed structure, and the recovery tendency after deep drawing is small. In addition, the organizational state of the aluminum alloy strip undergoes partial recrystallization, and the original fiber structure is partially retained, and the recrystallization ratio is 50~80%, and the proportion of recrystallized grains is high. The finer the grains, the better the stamping fluidity of the aluminum alloy strip, and the generation of U-shaped lines can be reduced after deep drawing, such as Figure 5 shown.

[0065] like Figure 2 As shown, the hot-rolled grain map is the grain state map of the hot-rolled billet after being magnified 200 times, the finished product grain map is the grain state map of the aluminum alloy after being magnified 200 times, the tensile MPa is the tensile strength of the aluminum alloy and the unit, the yield MPa is the yield strength of the aluminum alloy and the unit, the elongation % is the elongation rate of the aluminum alloy and the unit, the earing rate % is the earing rate of the aluminum alloy and the unit, the result is the U-shaped grain state of the aluminum alloy after deep drawing, and the remarks are the schematic diagram of the state of the aluminum alloy after deep drawing.

[0066] Among them, Scheme 1 is the normal deep-drawing material (aluminum alloy) production in the related art, and the state is O state; Scheme 2 is the hot-rolled billet in the related art using the first annealing process in this embodiment and the conventional complete recrystallization annealing method; Scheme 3 is the hot-rolled billet in the related art using the first annealing process in this embodiment, the state of the conventional finished product (aluminum alloy) after annealing is H24 state and the recrystallization ratio of the conventional finished product (aluminum alloy) is less than 50%; Scheme 4 is the hot-rolled billet in the related art using the first annealing process in this embodiment, conventional complete recrystallization annealing and limiting the earing rate of the aluminum alloy to less than 2%; Scheme 5 is produced using the process method of this embodiment. By comparison, it can be seen that the tensile strength and yield strength of the aluminum alloy strip produced by the process of this embodiment are higher than those of Schemes 1 to 4, the elongation is lower than that of Schemes 1 to 4, and the earing rate is in the last range. In addition, the aluminum alloy deep-drawing of Schemes 1 to 4 all have U-shaped patterns, but the aluminum alloy strip produced by the process of this embodiment does not have U-shaped patterns. Therefore, when the aluminum alloy strip in this embodiment is used as an electronic cigarette shell, it can be made without U-shaped lines after deep drawing, with good anode effect, and will not affect the appearance of the electronic cigarette shell.

[0067] Figure 6 This is a schematic diagram of the comparison of U-shaped patterns after deep drawing of aluminum alloy. The degree of U-shaped patterns decreases from left to right. Through comparison, it can be seen that the formation of U-shaped patterns seriously affects the appearance of aluminum alloy as an electronic cigarette shell.

[0068] Compared with the related art, the aluminum alloy strip in this embodiment is successively prepared by preparing ingots, sawing and milling the ingots, heating the ingots, hot rolling the ingots, cold rolling the hot-rolled billets after the first annealing, and annealing the cold-rolled coils, and the parameters of the heating treatment, hot rolling, the first annealing, cold rolling and the aluminum alloy strip are limited, so that an aluminum alloy strip with a tensile strength greater than 120 MPa, a yield strength greater than 80 MPa, no U-shaped patterns after deep drawing, and a fine surface and good brightness after anodizing can be obtained. When the aluminum alloy strip is used as the material of an electronic cigarette shell, it can be made without U-shaped patterns after deep drawing, with good anode effect, and will not affect the appearance of the electronic cigarette shell.

[0069] Embodiment 2

[0070] This embodiment provides an aluminum alloy strip, which is made by the aluminum alloy strip preparation method in the above-mentioned embodiment 1. The aluminum alloy strip is used to make a shell of an electronic cigarette.

[0071] Since the aluminum alloy strip in this embodiment is made by the preparation method of the aluminum alloy strip in the above embodiment, the aluminum alloy strip in this embodiment can also achieve the technical effect achieved by the preparation method of the aluminum alloy strip in the above embodiment, which will not be elaborated here.

[0072] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing an aluminum alloy strip, characterized in that: The method for preparing the aluminum alloy strip comprises the following steps: Step S1, preparing an ingot according to a raw material formula; Step S2, sawing and milling the ingot in sequence; Step S3, heating the milled ingot; the temperature of the ingot during the heating treatment is 490±15° C., and the heating treatment time is 4 to 8 hours; Step S4, hot rolling the ingot after the heating treatment to obtain a hot-rolled billet with a thickness of 8 to 9 mm; the hot rolling is carried out by a hot rolling mill, and the final rolling temperature of the hot rolling is 320 to 340° C. Before the hot rolling mill is used, a brush mark test is performed on the rollers of the hot rolling mill, and the brush mark width of the rollers of the hot rolling mill is 28 to 30 mm, and the thickness of the aluminum adhesion layer of the rollers of the hot rolling mill is 10 to 15 μm; when the hot rolling mill is used, the temperature of the F3 roller of the hot rolling mill is greater than 80° C. Step S5, performing a first annealing on the hot-rolled billet; the temperature of the first annealing is 500±15° C., and the time of the first annealing is 3 to 6 hours; Step S6, cold rolling the hot-rolled billet after the first annealing to obtain a cold-rolled coil with a thickness of 2.0 mm; the cold rolling reduction rate is 70-85%; and the rolling is performed in four passes, the roughness Ra of the rollers used in the first and second passes is 0.40±0.02μm, and the RPc is 100-200, and the roughness Ra of the rollers used in the third and fourth passes is 0.25±0.02μm, and the RPc is 130-150; Step S7, performing a second annealing on the cold-rolled coil to obtain an aluminum alloy strip; the performance of the aluminum alloy strip is in the H22-H24 state, and the earing rate of the aluminum alloy strip is 2.0-3.5%.

2. The method for preparing an aluminum alloy strip according to claim 1, characterized in that: In step S1, the components and mass percentages of the raw material formula are: Mg=0.7-0.9wt%, Si=0.5-0.6wt%, Fe≤0.10wt%, Mn≤0.02wt%, Cr≤0.03wt%, and the balance is Al.

3. The method for preparing an aluminum alloy strip according to claim 2, characterized in that: In the step S1, preparing the ingot according to the raw material formula includes the following sub-steps: S11, selecting aluminum ingots whose mass percentages of elements Mg, Si, Fe, Mn, Cr, and Al meet the raw material formula as a melt and putting them into a smelting furnace for smelting to obtain aluminum liquid; S12, performing a first refining on the aluminum liquid; the first refining adopts a particle refining agent and argon powder spraying refining, and the first refining time is 20 to 25 minutes; S13, transferring the aluminum liquid after the first refining into a holding furnace for a second refining; the second refining adopts a granular refining agent and argon powder spraying refining, and the second refining time is 30 to 35 minutes; S14, deslagging the aluminum liquid after the second refining and letting it stand for 60 to 120 minutes; S15, degassing the aluminum liquid after standing by using a degassing box, wherein the oxygen content in the degassing box is less than 0.12 mL / 100 gAl, and the degassing box uses a first-grade aluminum titanium boron wire to add a grain refiner online during the degassing process; S16, using a filter box to filter the degassed aluminum liquid; the filtered aluminum liquid is cast through a crystallizer to obtain the ingot.

4. The method for preparing an aluminum alloy strip according to claim 1, wherein: In the step S6, the rollers used in the third and fourth rolling passes are reversely ground before use, so that the roughness Ra of the rollers after 10 rolling passes is less than 0.25 μm.

5. The method for preparing an aluminum alloy strip according to claim 1, characterized in that: In the step S7, the recrystallization ratio of the aluminum alloy strip is 50-80%.

6. An aluminum alloy strip, characterized in that: The aluminum alloy strip is made by the method for preparing the aluminum alloy strip according to any one of claims 1 to 5, and the aluminum alloy strip is used to make a shell of an electronic cigarette.

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