TW201912807A - Method of producing aluminum sheet and application thereof - Google Patents

Abstract

Method of producing aluminum sheet and application thereof are provided by the present invention. Aluminum slabs with certain content of titanium is first provided. Then, finishing rolling temperature of the hot rolling procedure and annealing temperature of the annealing procedure are controlled. Moreover, at cold rolling procedure, intermediate annealing step is omitted. Therefore, aluminum sheet with low earring and specific yield strength can be produced.

Description

 Aluminum sheet manufacturing method and application thereof  

The present invention relates to a method for producing an aluminum sheet and an application thereof, and more particularly to a method for producing an aluminum sheet for a can.

The aluminum sheet for conventional cans is first heated to 500 ° C with an aluminum blank having a thickness of 500 to 600 mm, and the aluminum blank is rolled into a hot rolled aluminum coil having a thickness of about 2.4 mm to about 3.0 mm by a hot rolling mill. The rolling temperature of the rolled aluminum coil is 330 ° C to 360 ° C. Next, the hot rolled aluminum coil is subjected to a cold rolling step to cold-roll the hot rolled aluminum coil into a cold rolled aluminum coil having a thickness of about 0.4 mm to about 0.6 mm. Then, an intermediate annealing treatment of 300 ° C to 350 ° C is performed, and after the aluminum coil temperature is raised to a predetermined temperature, annealing and heat treatment is performed for 3 to 6 hours depending on the aluminum coil size, so that the cold rolled aluminum sheet is sufficiently softened, and then continues. Cold rolled to a thickness of 0.20 mm. Finally, the aluminum sheet is subjected to a low-temperature annealing treatment at 150 ° C to 200 ° C to make the finished aluminum sheet have a relief strength of 180 MPa to 200 MPa and a low ear rate of less than 2%, which meets the application requirements of the aluminum sheet for the can.

However, in the manufacturing process, the aluminum sheet in the can is prone to abnormal crystal structure or surface streaking defects due to the change in the mass percentage of the titanium element, thereby causing a low process efficiency. Furthermore, the process of performing two annealing treatments (i.e., the intermediate annealing treatment and the low temperature annealing treatment described above) also lengthens the production process, thereby deriving the disadvantage of energy consumption.

In view of this, it is not necessary to provide a method for manufacturing an aluminum sheet to improve the production efficiency of the aluminum sheet and reduce the process cost.

An aspect of the present invention provides a method for producing an aluminum sheet by controlling the titanium content of the aluminum blank, the rolling temperature of the hot rolling step, and the annealing temperature of the subsequent annealing step, and further omitting the intermediate annealing of the cold rolling step. Treatment to produce an aluminum sheet with a low lug rate.

Another aspect of the present invention provides an aluminum sheet for cans which is obtained by the above method.

According to an aspect of the present invention, there is provided a method of producing an aluminum sheet. First, an aluminum embryo is provided, the aluminum embryo comprising 0.012% to 0.025% of titanium. Next, the aluminum blank is subjected to a hot rolling step, and the rolling temperature of the hot rolling step is controlled to be 310 ° C to 330 ° C to obtain a hot rolled aluminum coil. Then, the aforementioned hot rolled aluminum coil is subjected to a cold rolling step to obtain a cold rolled aluminum coil. The intermediate annealing treatment is not performed in the cold rolling step. Next, the cold rolled aluminum coil is subjected to an annealing step, and the annealing step is performed at an annealing temperature of 210 to 225 ° C to obtain an aluminum sheet having a tab ratio of not more than 2%.

According to an embodiment of the present invention, the aluminum embryo further comprises no more than 0.15% bismuth, no more than 0.25% iron, no more than 0.15% copper, no more than 0.10% chromium, no more than 0.10% manganese, 1.5%. To 2.0% magnesium, and the balance is aluminum.

According to an embodiment of the present invention, the hot rolled aluminum coil has a thickness of 2.4 mm to 3.0 mm.

According to an embodiment of the present invention, the cold rolled aluminum coil has a thickness of 0.20 mm.

According to an embodiment of the invention, the reduction ratio of the cold rolling step is greater than 90%.

According to an embodiment of the invention, the annealing time of the annealing step is 3 hours.

According to an embodiment of the present invention, the aluminum sheet has a lug ratio of 1.0% to 1.8%.

According to another aspect of the present invention, there is provided an aluminum sheet for a can which is obtained by the method of the above aspect, and the aluminum sheet for a can has a relief strength of from 180 MPa to 200 MPa.

According to an embodiment of the present invention, the aluminum sheet for the can has a relief strength of 184 MPa to 192 MPa.

A method for producing an aluminum sheet according to the present invention, which utilizes an aluminum blank having a specific titanium content, and which has a low lug by controlling the rolling temperature and the subsequent annealing temperature, and omitting the intermediate annealing treatment of the cold rolling step The aluminum sheet with a specific and reduced strength can be applied as an aluminum sheet for cans.

100‧‧‧ method

110‧‧‧ Providing aluminum embryos

120‧‧‧ Hot rolling of aluminum blanks to obtain hot rolled aluminum coils

130‧‧‧Cold-rolling hot-rolled aluminum coils to obtain cold-rolled aluminum coils

140‧‧‧Annealed the cold rolled aluminum coil to produce an aluminum sheet

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

FIG. 1 is a flow chart showing a method of manufacturing an aluminum sheet according to an embodiment of the present invention.

An embodiment of the present invention provides a method for manufacturing an aluminum sheet by using an aluminum sheet containing a specific composition, and by controlling the process conditions, an aluminum sheet meeting the application requirements can be obtained, while improving process efficiency and reducing process cost.

Please refer to FIG. 1 , which is a flow chart of a method 100 for manufacturing an aluminum sheet according to an embodiment of the invention. First, step 110 is performed to provide an aluminum embryo. Among them, the aluminum embryo contains 0.012 to 0.025% of titanium based on 100% of the aluminum embryo. In one embodiment, the aluminum blank may comprise no more than 0.15% bismuth, no more than 0.25% iron, no more than 0.15% copper, no more than 0.10% chromium, no more than 0.10% manganese, and 1.5% to 2.0%. Magnesium, and the rest is aluminum. The invention controls the content of the titanium element as a seed crystal in the aluminum embryo to avoid defects in the aluminum embryo during the manufacturing process. If the content of titanium in the aluminum embryo is too small, for example, less than 0.012%, since the crystal seed is too small, crystals are not easily generated, and the aluminum embryo is coarsened, and the surface of the crystal grains is caused by the subsequent process. defect. However, if the titanium content is excessive, for example, more than 0.025%, hard particles of titanium boride (TiB ₂ ) are easily generated in the aluminum embryo, and the aluminum embryo is caused by the aggregation of hard particles of TiB ₂ during the subsequent cold rolling. Embryo rupture.

Next, in step 120, the aluminum blank is subjected to a hot rolling step to obtain a hot rolled aluminum coil. In one embodiment, step 120 is to hot-roll the thickness of the aluminum blank into a hot rolled aluminum coil having a thickness of about 2.4 mm to about 3.0 mm, and control the finishing temperature of the hot rolling step to be 310 ° C to 330 ° C to ensure The resulting hot rolled aluminum coil is fully softened. If the finishing temperature is lower than 310 ° C, the rolled-rolled assembly of the hot-rolled aluminum coil is too strong (that is, the soft-rolled aluminum coil is not soft enough), and the subsequent process cannot be performed. If the finish rolling temperature is higher than 330 ° C, although the hot rolled aluminum coil is sufficiently softened, the excessively high rolling temperature only increases the process cost without any other benefit. Therefore, by controlling the rolling temperature at 310 ° C to 330 ° C, the hot rolled aluminum coil which has been sufficiently softened can be obtained, and the process cost can be reduced.

After performing step 120, step 130 is performed to perform a cold rolling step on the hot rolled aluminum coil to obtain a cold rolled aluminum coil. In one embodiment, step 130 is to roll the thickness of the hot rolled aluminum coil to a thickness of the finished product, such as 0.20 mm (i.e., the thickness of the previously cold rolled aluminum coil). In another embodiment, the reduction rate of the cold rolling step is greater than 90%. Compared with the conventional process, the present invention can control the rolling temperature of the step 120 to omit the intermediate annealing treatment of the cold rolling step, without the need of multiple cold rolling and intermediate annealing treatment, the hot rolled aluminum coil can be rolled. The invention is extended to the required thickness, so the invention can save process cost and reduce the process.

Next, in step 140, the cold rolled aluminum coil is subjected to an annealing step to obtain an aluminum sheet. In one embodiment, the annealing step has an annealing temperature of 210 ° C to 225 ° C. In another embodiment, the incubation time of the annealing step can be, for example, 3 hours. The annealing step of the present invention is partial annealing, that is, the annealing temperature is between the full annealing and the aging heat treatment. Thereby, after the annealing step of the present invention, the strength of the obtained aluminum sheet is higher than that of the completely annealed material, and the ductility of the aluminum sheet is higher than that of the material after the aging heat treatment. Therefore, if the annealing temperature is higher than 225 ° C, the annealing step is closer to complete annealing, so the strength of the obtained aluminum sheet is lower; if the annealing temperature is lower than 210 ° C, the annealing step is similar to the aging heat treatment, so The resulting aluminum sheet is less ductile.

With the above-described aluminum sheet manufacturing method 100, the aluminum sheet obtained by the present invention has a lodging strength of 180 MPa to 200 MPa, and preferably 184 MPa to 192 MPa. Further, the aluminum sheet thus obtained has a tab ratio of not more than 2%, and preferably 1.0% to 1.8%. The mechanical properties and surface quality of the aluminum sheet can meet the requirements of aluminum sheets for cans.

In addition, the above-mentioned "ear rate" refers to the cup forming of aluminum sheets, which is punched into a round cup, and different deformation amounts are generated along the edge of the cup, which is in the direction of cold rolling. 45, 135, 225 or 315 degrees are easy to extend and deform according to external stress, and form a peak; and 0, 90, 180 or 270 degrees with the cold rolling direction is less likely to conform to external stress and extend deformation, thus forming a trough. Among them, due to the anisotropy inside the material, the round cup after punching is easy to generate peaks and troughs in the specific direction, and the cup edge of the round cup has a height difference.

In the embodiment of the present invention, the measuring procedure of the ear tab rate of the aluminum sheet is first cut into a wafer having a diameter of 55 mm in accordance with the provisions of JIS Z2247. Then, using a Roell+Korthaus AMSLER Type BUP 200 cupping machine, it was punched into a round cup with an inner diameter of 33 mm, and then the heights of the crests and troughs were measured along the circumferential direction of the upper edge of the cup. The percentage of the height of the cup is the ear rate.

The following examples are used to illustrate the application of the present invention, and are not intended to limit the present invention. Those skilled in the art can make various changes without departing from the spirit and scope of the present invention. Retouching.

Example 1

The aluminum blank having a titanium content of 0.012% was subjected to the above-described method for producing an aluminum sheet. First, the aluminum blank was subjected to a hot rolling step at a rolling temperature of 310 ° C to obtain a hot rolled aluminum coil. Next, the hot rolled aluminum coil was subjected to a cold rolling step to obtain a cold rolled aluminum coil having a thickness of 0.20 mm. Then, the cold rolled aluminum coil was subjected to an annealing step of an annealing temperature of 210 ° C to obtain an aluminum sheet having a relief strength of 192 MPa and a lug ratio of 1.8%. The process conditions of Example 1 and the properties of the aluminum sheets are shown in Table 1.

Examples 2 to 4 and Comparative Examples 1 to 8

The process methods of Examples 2 to 4 and Comparative Examples 1 to 8 are the same as those of Example 1, except that the titanium content of the aluminum embryo, the annealing temperature and the finishing temperature, the process conditions and the properties of the obtained aluminum sheet are shown in the table. 1 is shown.

According to Table 1 above, Examples 1 to 4 are when the aluminum content of the aluminum embryo is 0.012% to 0.025%, the rolling temperature of the hot rolling step is 310 ° C to 330 ° C, and the annealing temperature of the annealing step is 210 ° C to 225 ° C. And the aluminum sheet produced has a lodging strength of 184 to 198 MPa and a lug ratio of 1.0% to 1.8%.

In Comparative Example 1, since the aluminum content of the aluminum embryo used was low, the aluminum embryo had a phenomenon in which the crystal grains were coarse, and after the rolling and annealing step, abnormal pattern defects were caused on the surface of the coarse crystal grain region. Therefore, even if the mechanical properties of the aluminum sheet produced in Comparative Example 1 meet the specifications, the surface quality is defective and cannot meet the requirements of the aluminum sheet for can. In contrast, Comparative Example 2 used an aluminum embryo having a high titanium content, and thus had casting defects due to aggregation of TiB ₂ particles. During the cold rolling step, the surface of the hot rolled aluminum coil of Comparative Example 2 easily produced stripe stripe defects along the TiB ₂ aggregated particles, thereby forcing the production process to be stopped.

In Comparative Example 3, since the annealing temperature of the annealing step was low, the yield strength and the lug ratio of the obtained aluminum sheet were too high, and exceeded the specifications of the aluminum sheet for can. On the contrary, in Comparative Example 4, the annealing temperature of the annealing step was too high, and the aluminum sheet obtained had a too low drop strength, and the ear rate was too high, which did not conform to the specifications of the aluminum sheet for the can.

In Comparative Examples 5 and 6, the rolling-rolled microstructure of the hot-rolled aluminum coil was too strong due to the low finish rolling temperature, and the annealing strength of the obtained aluminum sheet reached the specification requirement at an annealing temperature of 210 ° C to 225 ° C . Because of its high 45-degree lug rate, it does not meet the specifications of the aluminum sheet for cans. Further, in Comparative Examples 7 and 8, since the rolling temperature of the hot rolling step was too high, the cubic aggregate structure of the hot rolled aluminum coil was too strong, and even in the same annealing temperature range as above, even the obtained aluminum was obtained. The sheet's lodging strength can meet the specification requirements, but its 90-degree azimuth is too high to meet the specifications of the aluminum sheet for cans.

The method for manufacturing an aluminum sheet provided by the present invention utilizes an aluminum embryo having a specific titanium content and includes a hot rolling step, a cold rolling step and an annealing step, wherein the rolling temperature of the hot rolling step and the annealing step are controlled. The temperature and the intermediate annealing treatment of the cold rolling step are omitted, whereby an aluminum sheet conforming to the specification of the aluminum sheet for the can, and having a low lug ratio and a specific relief strength can be obtained. At the same time, the efficiency of the process can be improved and the cost of the process can be reduced.

While the invention has been described above in terms of several embodiments, it is not intended to limit the scope of the invention, and the invention may be practiced in various embodiments without departing from the spirit and scope of the invention. The scope of protection of the present invention is defined by the scope of the appended claims.

Claims (9)

 A method for producing an aluminum sheet, comprising: providing an aluminum embryo, wherein the aluminum embryo comprises 100% based on the aluminum embryo, and the aluminum embryo comprises 0.012% to 0.025% titanium; and the aluminum embryo is subjected to a hot rolling step to obtain a hot rolling An aluminum coil, wherein one of the hot rolling steps has a rolling temperature of 310 ° C to 330 ° C; a cold rolling step is performed on the hot rolled aluminum coil to obtain a cold rolled aluminum coil, wherein the cold rolling step does not perform an intermediate annealing Processing; and performing an annealing step on the cold rolled aluminum coil to obtain the aluminum sheet, wherein one of the annealing steps has an annealing temperature of 210 to 225 ° C, and the aluminum sheet has a tab ratio of not more than 2% .    The method for producing an aluminum sheet according to claim 1, wherein the aluminum embryo further comprises not more than 0.15% bismuth, not more than 0.25% iron, not more than 0.15% copper, not more than 0.10% chromium, Not more than 0.10% manganese and 1.5% to 2.0% magnesium, and the balance is aluminum.    The method for producing an aluminum sheet according to claim 1, wherein the hot rolled aluminum coil has a thickness of 2.4 mm to 3.0 mm.    The method for producing an aluminum sheet according to claim 1, wherein the cold rolled aluminum coil has a thickness of 0.20 mm.    The method for producing an aluminum sheet according to claim 1, wherein a reduction ratio of the cold rolling step is greater than 90%.    The method for producing an aluminum sheet according to claim 1, wherein the annealing step has a holding time of 3 hours.    The method for producing an aluminum sheet according to claim 1, wherein the aluminum sheet has a tab ratio of 1.0% to 1.8%.    An aluminum sheet for cans obtained by the method according to any one of claims 1 to 7, and the aluminum sheet for the can has a relief strength of 180 MPa to 200 MPa.    The aluminum sheet for cans according to claim 8, wherein the aluminum sheet for the can has a relief strength of 184 MPa to 192 MPa.