Aluminum alloy sheet and method for manufacturing the same

Abstract

The present invention provides an aluminum alloy sheet that can be made thinner while maintaining high strength, and a method for manufacturing the same. [Solution] The aluminum alloy plate has a chemical composition containing Si: 0.40% to 1.1% by mass, Fe: 0% to 0.70% by mass, Cu: 0% to 1.1% by mass, Mg: 0.40% to 1.2% by mass, Cr: 0% to 0.35% by mass, Mn: 0% to 0.80% by mass, Zn: 0% to 0.25% by mass, and Ti: 0% to 0.15% by mass, with the remainder being Al and unavoidable impurities, a thickness of 0.1 mm to 2.5 mm, and a 0.2% yield strength of 385 MPa or more.

Description

Technical Field

[0001] The present invention relates to an aluminum alloy plate and a method for producing the same.

Background Art

[0002] 6000-series aluminum alloy plates have relatively high strength among aluminum alloys, and are therefore used in various applications such as casings for electronic devices, exterior materials for vehicles, and building materials.

[0003] For example, Patent Document 1 describes an aluminum alloy body containing 0.1 to 2.0 wt% of silicon and 0.1 to 3.0 wt% of magnesium, wherein at least one of silicon and magnesium is a main alloying element other than aluminum in the aluminum alloy body, the aluminum alloy body contains at least one of (A) at least 1.1 wt% of Mg, (B) 0.35 to 2.0 wt% of Cu, and (C) 0.35 to 2.0 wt% of Zn, a majority of the aluminum alloy body is not recrystallized, and the aluminum alloy body achieves a maximum normalized R-value of at least 3.0.

[0004] The aluminum alloy body of Patent Document 1 is obtained by performing a preparation step (a) including a solution treatment step, then performing a cold working step (b) of subjecting the aluminum alloy body to cold working of at least 50%, and further performing a heat treatment step (c) of subjecting the aluminum alloy body to heat treatment.

Prior Art Literature

Patent Literature

[0005]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0006] In recent years, there has been a growing demand for lighter electronic devices and vehicles, and from this perspective, there is a need to reduce the thickness of aluminum alloy sheets while maintaining their high strength.

[0007] This invention was made in view of the above background, and aims to provide an aluminum alloy sheet and a method for manufacturing the same that can be made thinner while maintaining high strength. [Means for solving the problem]

[0008] One aspect of the present invention is a chemical composition containing Si (silicon): 0.40% to 1.1% by mass, Fe (iron): 0% to 0.70% by mass, Cu (copper): 0% to 1.1% by mass, Mg (magnesium): 0.40% to 1.2% by mass, Cr (chromium): 0% to 0.35% by mass, Mn (manganese): 0% to 0.80% by mass, Zn (zinc): 0% to 0.25% by mass, and Ti (titanium): 0% to 0.15% by mass, with the remainder being Al (aluminum) and unavoidable impurities. A thickness of 0.1 mm or more and 2.5 mm or less, With a 0.2% yield strength of 385 MPa or higher, An increase of over 8%, It is located on an aluminum alloy plate.

[0009] Other aspects of the present invention include: Si: 0.40 mass% or more and 1.1 mass% or less, Fe: 0 mass% or more and 0.70 mass% or less, Cu: 0 mass% or more and 1.1 mass% or less, Mg: 0.40 mass% or more and 1.2 mass% or less, Cr: 0 mass% or more and 0.35 A chemical component containing Mn: 0 mass% or more and 0.80 mass% or less, Zn: 0 mass% or more and 0.25 mass% or less, and Ti: 0 mass% or more and 0.15 mass% or less, with the balance consisting of Al and inevitable impurities; A thickness of 0.1 mm or more and 2.5 mm or less, It has a 0.2% yield strength of 385 MPa or higher. A method for manufacturing aluminum alloy plates, Prepare an ingot having the aforementioned chemical components. The process and , Hot rolling is performed on the ingot while its temperature at the start of rolling is 490°C or higher. The process and , The rolled sheet obtained by the hot rolling process is subjected to solution treatment by heating it under conditions such that the time the temperature of the rolled sheet is within the range of 500°C to 580°C is 300 seconds or less, followed by quenching. The process and , Subsequently, the rolled plate is cold-rolled under conditions that result in a reduction ratio of 40% or more. The process and , The cold-rolled rolled sheet is subjected to a period of time during which the temperature of the rolled sheet is between 100°C and 220°C for at least 1 hour and at least 48 hours. below The artificial aging process is performed by heating under the following conditions. Process and, including This relates to the manufacturing method of aluminum alloy sheets. [Effects of the Invention]

[0010] According to the above embodiment, it is possible to provide an aluminum alloy sheet and a method for manufacturing the same that can be made thinner while maintaining high strength. [Modes for carrying out the invention]

[0011] (Aluminum alloy plate) The chemical composition, properties, and reasons for limitations of the aforementioned aluminum alloy plate will be explained.

[0012] [Chemical composition] ·Si: 0.40 mass% or more and 1.1 mass% or less The aforementioned aluminum alloy sheet contains 0.40% by mass or more and 1.1% by mass or less of Si as an essential component. The Si in the aluminum alloy sheet forms a β'' phase together with Mg, and has the effect of improving the strength of the aluminum alloy sheet through precipitation strengthening. By setting the Si content in the aluminum alloy sheet to 0.40% by mass or more, the strength of the aluminum alloy sheet can be further improved.

[0013] Furthermore, in recent years, in order to reduce the environmental impact when manufacturing aluminum alloy sheets, it has been considered to use recovered materials, such as aluminum scrap and used aluminum products, that are recovered during the manufacturing, distribution, and disposal of aluminum products, as part of the casting raw materials. By setting the Si content in the aluminum alloy sheet to 0.40% by mass or more, even when recovered materials are used as the casting raw materials for aluminum alloy sheets, the Si content in the aluminum alloy sheet can be easily adjusted to a specific range.

[0014] From the perspective of further increasing the strength of the aluminum alloy sheet, the content of Si in the aluminum alloy sheet is preferably 0.45 mass% or more, more preferably 0.50 mass% or more, and still more preferably 0.55 mass% or more. If the Si content in the aluminum alloy sheet is less than 0.40 mass%, the strength of the aluminum alloy sheet may be reduced.

[0015] On the other hand, when the Si content in the aluminum alloy sheet is excessively high, coarse crystallized products are likely to be formed in the aluminum alloy sheet, which may lead to a decrease in the bendability of the aluminum alloy sheet. Such a problem can be easily avoided by setting the Si content in the aluminum alloy sheet to 1.1 mass% or less, preferably 1.0 mass% or less, more preferably 0.90 mass% or less, and still more preferably 0.80 mass% or less.

[0016] In determining the preferred range of the Si content in the aluminum alloy sheet, the upper limit and the lower limit of the Si content described above can be arbitrarily combined. For example, the preferred range of the Si content in the aluminum alloy sheet may be 0.45 mass% to 1.0 mass%, may be 0.50 mass% to 0.90 mass%, or may be 0.55 mass% to 0.80 mass%.

[0017] · Fe: 0 mass% or more and 0.70 mass% or less The aluminum alloy sheet may contain 0.70 mass% or less of Fe as an optional component. By setting the Fe content in the aluminum alloy sheet within the specific range, the formation of coarse crystallized products can be easily avoided. As a result, a decrease in the bendability of the aluminum alloy sheet can be easily avoided. In addition, in this case, even when a recovered material is used as the casting raw material for the aluminum alloy sheet, the Fe content in the aluminum alloy sheet can be easily adjusted to within the specific range.

[0018] From the viewpoint of more easily avoiding the formation of coarse precipitates, the Fe content in the aluminum alloy sheet is preferably 0.65% by mass or less, more preferably 0.60% by mass or less, even more preferably 0.55% by mass or less, and particularly preferably 0.50% by mass or less. On the other hand, the Fe content in the aluminum alloy sheet may be, for example, 0.05% by mass or more, or 0.10% by mass or more.

[0019] The preferred range for the Fe content in the aluminum alloy sheet can be any combination of the upper and lower limits of the preferred range for Fe content described above. For example, the preferred range for the Fe content in the aluminum alloy sheet may be 0.05% by mass or more and 0.60% by mass or less, 0.05% by mass or more and 0.55% by mass or less, or 0.10% by mass or more and 0.50% by mass or less.

[0020] ·Cu: 0 mass% or more and 1.1 mass% or less The aluminum alloy sheet may contain 1.1% by mass or less of Cu as an optional component. Cu forms a Q phase together with Mg and Si, and has the effect of improving the strength of the aluminum alloy sheet through precipitation strengthening. Therefore, by adding Cu to the aluminum alloy sheet, the strength of the aluminum alloy sheet can be further improved. From the viewpoint of obtaining this effect more reliably, the Cu content in the aluminum alloy sheet is preferably 0.05% by mass or more, and more preferably 0.15% by mass or more. Furthermore, by preferably setting the Cu content to 0.05% by mass or more, and more preferably 0.15% by mass or more, the Cu content in the aluminum alloy sheet can be easily adjusted to the above-mentioned specific range even when using recovered material as a casting raw material for the aluminum alloy sheet.

[0021] If the Cu content in the aluminum alloy sheet is excessively high, coarse precipitates are likely to form in the aluminum alloy sheet, which may lead to a decrease in the strength of the aluminum alloy sheet. This problem can be easily avoided by setting the Cu content in the aluminum alloy sheet to 1.1% by mass or less, preferably 1.0% by mass or less, and more preferably 0.90% by mass or less.

[0022] In determining the preferred range for the Cu content in the aluminum alloy sheet, the aforementioned upper and lower limits for the Cu content can be arbitrarily combined. For example, the preferred range for the Cu content in the aluminum alloy sheet may be 0.05% by mass or more and 1.0% by mass or less, or 0.15% by mass or more and 0.90% by mass or less.

[0023] ·Mg: 0.40 mass% or more and 1.2 mass% or less The aluminum alloy sheet contains 0.40% by mass or more and 1.2% by mass or less of Mg as an essential component. The Mg in the aluminum alloy sheet forms a β'' phase together with Si, and has the effect of improving the strength of the aluminum alloy sheet through precipitation strengthening. By setting the Mg content in the aluminum alloy sheet to 0.40% by mass or more, the strength of the aluminum alloy sheet can be further improved. In this case, even when using recovered material as a casting raw material for the aluminum alloy sheet, the Mg content in the aluminum alloy sheet can be easily adjusted to the specified range.

[0024] From the viewpoint of further increasing the strength of the aluminum alloy sheet, the Mg content in the aluminum alloy sheet is preferably 0.45% by mass or more, more preferably 0.50% by mass or more, and even more preferably 0.55% by mass or more. If the Mg content in the aluminum alloy sheet is less than 0.40% by mass, it may lead to a decrease in the strength of the aluminum alloy sheet.

[0025] On the other hand, if the Mg content in the aluminum alloy sheet is excessively high, it may lead to a decrease in the conductivity of the aluminum alloy sheet. This problem can be easily avoided by keeping the Mg content in the aluminum alloy sheet to 1.2 mass% or less.

[0026] In determining a preferred range for the Mg content in the aluminum alloy sheet, the aforementioned upper and lower limits for the Mg content can be arbitrarily combined. For example, the Mg content in the aluminum alloy sheet may be 0.45% by mass or more and 1.2% by mass or less, 0.50% by mass or more and 1.2% by mass or less, or 0.55% by mass or more and 1.2% by mass or less.

[0027] ·Cr: 0 mass% or more and 0.35 mass% or less The aluminum alloy sheet may contain 0.35% by mass or less of Cr as an optional component. By keeping the Cr content in the aluminum alloy sheet within the specified range, the formation of coarse precipitates can be easily avoided. As a result, a decrease in the strength of the aluminum alloy sheet can be easily avoided. Furthermore, in this case, even when using recovered material as the casting raw material for the aluminum alloy sheet, the Cr content in the aluminum alloy sheet can be easily adjusted to within the specified range.

[0028] From the viewpoint of more easily avoiding the formation of coarse precipitates, the Cr content in the aluminum alloy plate is preferably 0% by mass or more and 0.30% by mass or less, more preferably 0% by mass or more and 0.15% by mass or less, even more preferably 0% by mass or more and 0.15% by mass or less, particularly preferably 0% by mass or more and 0.05% by mass or less, and most preferably 0% by mass or more and 0.01% by mass or less.

[0029] ·Mn: 0 mass% or more and 0.80 mass% or less The aluminum alloy sheet may contain 0.80% by mass or less of Mn as an optional component. By keeping the Mn content in the aluminum alloy sheet within the specified range, the formation of coarse precipitates can be easily avoided. As a result, a decrease in the bendability of the aluminum alloy sheet can be easily avoided. Furthermore, in this case, even when using recovered material as the casting raw material for the aluminum alloy sheet, the Mn content in the aluminum alloy sheet can be easily adjusted to within the specified range.

[0030] From the viewpoint of more easily avoiding the formation of coarse precipitates, the Mn content in the aluminum alloy sheet is preferably 0.60% by mass or less, more preferably 0.45% by mass or less, even more preferably 0.30% by mass or less, and particularly preferably 0.25% by mass or less. On the other hand, the Mn content in the aluminum alloy sheet may be, for example, 0.05% by mass or more, or 0.10% by mass or more.

[0031] The preferred range for the Mn content in the aluminum alloy sheet can be any combination of the upper and lower limits of the preferred range for the Mn content described above. For example, the preferred range for the Mn content in the aluminum alloy sheet may be 0% by mass or more and 0.60% by mass or less, 0.05% by mass or more and 0.45% by mass or less, 0.05% by mass or more and 0.30% by mass or less, or 0.10% by mass or more and 0.25% by mass or less.

[0032] ·Zn: 0 mass% or more and 0.25 mass% or less The aluminum alloy sheet may contain 0.25% by mass or less of Zn as an optional component. By keeping the Zn content in the aluminum alloy sheet within the specified range, the formation of coarse precipitates can be easily avoided. As a result, a decrease in the strength of the aluminum alloy sheet can be easily avoided. Furthermore, in this case, even when recycled material is used as the casting raw material for the aluminum alloy sheet, the Zn content in the aluminum alloy sheet can be easily adjusted to within the specified range.

[0033] From the viewpoint of more easily avoiding the formation of coarse precipitates, the Zn content in the aluminum alloy plate is preferably 0% by mass or more and 0.20% by mass or less, more preferably 0% by mass or more and 0.15% by mass or less, even more preferably 0% by mass or more and 0.10% by mass or less, and particularly preferably 0% by mass or more and 0.05% by mass or less.

[0034] ·Ti: 0 mass% or more and 0.15 mass% or less The aluminum alloy sheet may contain 0.15% by mass or less of Ti as an optional component. By keeping the Ti content in the aluminum alloy sheet within the specified range, the formation of coarse precipitates can be easily avoided. As a result, a decrease in the strength of the aluminum alloy sheet can be easily avoided. Furthermore, in this case, even when using recovered material as the casting raw material for the aluminum alloy sheet, the Ti content in the aluminum alloy sheet can be easily adjusted to within the specified range.

[0035] From the viewpoint of more easily avoiding the formation of coarse precipitates, the Ti content in the aluminum alloy plate is preferably 0% by mass or more and 0.10% by mass or less, and particularly preferably 0% by mass or more and 0.05% by mass or less.

[0036] From the viewpoint of reducing the thickness of the aluminum alloy sheet while maintaining its high strength, the aluminum alloy sheet may have a chemical composition containing Si: 0.40% to 1.1% by mass, Fe: 0% to 0.70% by mass, Cu: 0% to 1.1% by mass, Mg: 0.40% to 1.2% by mass, Mn: 0% to 0.80% by mass, Cr: 0% to 0.35% by mass, and Ti: 0% to 0.15% by mass, with the remainder being Al and unavoidable impurities.

[0037] [Thickness and 0.2% yield strength] The thickness of the aluminum alloy plate is 0.1 mm or more and 2.5 mm or less. The 0.2% yield strength of the aluminum alloy plate is 385 MPa or more. Despite having such a relatively thin thickness, the aluminum alloy plate has a high yield strength of 385 MPa or more. Therefore, by using the aluminum alloy plate, the mass of electronic equipment, vehicles, etc. can be reduced more easily. From the viewpoint of making the aluminum alloy plate thinner while maintaining high strength, the thickness of the aluminum alloy plate is preferably 0.1 mm or more and less than 2.0 mm, more preferably 0.1 mm or more and 1.5 mm or less, even more preferably 0.1 mm or more and 1.0 mm or less, and particularly preferably 0.1 mm or more and 0.8 mm or less.

[0038] 〔stretch〕 The elongation of the aforementioned aluminum alloy plate is It is over 8%. This allows for further improvement of the formability of the aluminum alloy sheet.

[0039] (Manufacturing method for aluminum alloy sheets) The aluminum alloy plate is prepared, for example, by preparing an ingot having the chemical composition. Hot rolling is performed on the ingot while its temperature at the start of rolling is 490°C or higher. The rolled sheet obtained by the hot rolling is subjected to solution treatment by heating it under conditions such that the time the temperature of the rolled sheet is in the range of 500°C to 580°C is 300 seconds or less, followed by quenching. Subsequently, the rolled plate is subjected to cold rolling under conditions that result in a reduction ratio of 40% or more. The rolled sheet, after cold rolling, is subjected to artificial aging treatment by heating it under conditions that the temperature of the rolled sheet remains within the range of 100°C to 220°C for 1 hour to 48 hours. The steps of the manufacturing method will be described in detail below.

[0040] [Preparation of the ingot] The ingot used to produce the aforementioned aluminum alloy plate can be obtained by various methods. For example, the ingot may be produced by DC casting or by continuous casting.

[0041] [Hot rolling] In the above manufacturing method, a rolled sheet is produced by hot rolling the ingot while its temperature is 490°C or higher at the start of rolling. Within the ingot having the above chemical composition, there are coarse Mg2Si particles that are formed as the temperature of the ingot decreases. If hot rolling and subsequent processes are carried out with the presence of such Mg2Si particles, it becomes difficult to form the β'' phase in the aluminum alloy sheet, which may lead to a decrease in the strength of the aluminum alloy sheet.

[0042] In contrast, by performing hot rolling on the ingot while its temperature is 490°C or higher at the start of rolling, the Mg2Si particles within the ingot can be dissolved in the Al matrix. Then, by performing hot rolling and subsequent processes in this state, a β'' phase can be formed in the aluminum alloy sheet, improving the strength of the aluminum alloy sheet.

[0043] From the viewpoint of more reliably dissolving the Mg2Si particles in the ingot into the Al matrix, the temperature of the ingot at the start of rolling is preferably 500°C or higher, more preferably 510°C or higher, even more preferably 520°C or higher, and particularly preferably 530°C or higher. If the temperature of the ingot at the start of rolling is below 490°C, the solid dissolution of the Mg2Si particles into the Al matrix will be insufficient, which may lead to a decrease in the strength of the aluminum alloy sheet.

[0044] Furthermore, the temperature of the ingot at the start of rolling is preferably 600°C or lower, more preferably 590°C or lower, even more preferably 580°C or lower, and particularly preferably 570°C or lower. In this case, localized melting of the ingot during hot rolling can be more easily avoided, and a sound rolled sheet can be produced more easily.

[0045] The preferred temperature range for the ingot at the start of rolling can be any combination of the upper and lower limits of the ingot temperature mentioned above. For example, the preferred temperature range for the ingot at the start of rolling may be 490°C to 600°C, 500°C to 590°C, 510°C to 580°C, 520°C to 580°C, or 530°C to 570°C.

[0046] When performing hot rolling, the ingot may be heated to a temperature of 490°C or higher and then immediately hot-rolled. However, it is preferable to maintain the temperature at 490°C or higher for at least one hour before hot-rolling. By maintaining the temperature of the ingot for at least one hour in this way, coarse Mg2Si particles can be sufficiently dissolved in the Al matrix, and the structure of the ingot can be homogenized. As a result, the strength of the aluminum alloy sheet can be improved more easily.

[0047] From the viewpoint of further enhancing these effects, it is preferable that the ingot temperature be maintained for 2 hours or more, and more preferably for 3 hours or more, before hot rolling. From the viewpoint of sufficiently dissolving Mg2Si particles in the Al matrix and homogenizing the structure of the ingot, there is no upper limit to the time the ingot temperature is maintained before hot rolling. However, from the viewpoint of further increasing the productivity of the aluminum alloy sheet, it is preferable that the ingot temperature be maintained for 24 hours or less before hot rolling.

[0048] From the viewpoint of more easily maintaining the temperature of the ingot at the start of rolling within the aforementioned specific range, the holding temperature during heating of the ingot before hot rolling is preferably 500°C to 600°C, more preferably 500°C to 590°C, and even more preferably 500°C to 580°C.

[0049] A rolled sheet is obtained by performing the aforementioned hot rolling. The thickness of the rolled sheet after hot rolling can be appropriately set according to the desired thickness of the aluminum alloy sheet and the reduction ratio in cold rolling after solution treatment. In order to adjust the thickness of the rolled sheet after hot rolling, cold rolling can be performed as needed between hot rolling and solution treatment.

[0050] [Solution treatment] In the solution treatment, first, the rolled sheet obtained by hot rolling is heated under conditions that the temperature is within the range of 500°C to 580°C for 300 seconds or less. This causes the Mg2Si particles and other precipitates and crystals formed in the rolled sheet after hot rolling to be dissolved in the Al matrix. Subsequently, the rolled sheet is quenched to create a supersaturated solid solution. In this way, after creating a supersaturated solid solution in the rolled sheet through the solution treatment, cold rolling and artificial aging treatment are performed to form a fine β'' phase in the aluminum alloy sheet, thereby improving the strength of the aluminum alloy sheet.

[0051] If the maximum temperature of the rolled sheet during the solution treatment is too low, it becomes difficult to sufficiently solid-solve the Mg2Si particles and other elements within the sheet. This can lead to a decrease in the strength of the aluminum alloy sheet. Conversely, if the maximum temperature of the rolled sheet during the solution treatment is too high, there is a risk of localized melting of the aluminum alloy sheet due to eutectic melting. From the viewpoint of easily avoiding these problems and more easily obtaining an aluminum alloy sheet with high strength, the maximum temperature of the rolled sheet during the solution treatment is preferably 510°C to 575°C, and more preferably 520°C to 570°C.

[0052] If the heating time of the rolled sheet during the solution treatment, that is, the time from when the temperature of the rolled sheet reaches 500°C until it falls below 500°C, is too long, the productivity of the aluminum alloy sheet may decrease. Furthermore, especially when heating the rolled sheet using a batch furnace, if the heating time of the rolled sheet extends to several hours, distortion and warping are likely to occur in the rolled sheet, making it difficult to obtain a flat aluminum alloy sheet. By setting the heating time of the rolled sheet during the solution treatment to 300 seconds or less, preferably 200 seconds or less, more preferably 120 seconds or less, even more preferably 100 seconds or less, particularly preferably 80 seconds or less, and most preferably 60 seconds or less, these problems can be easily avoided, and the aluminum alloy sheet can be obtained.

[0053] From the viewpoint of sufficiently solid-solving the Mg2Si particles and the like present in the rolled sheet, the heating time of the rolled sheet in the solution treatment is preferably 10 seconds or more, more preferably 20 seconds or more, and even more preferably 30 seconds or more.

[0054] In determining the preferred range for heating the rolled sheet in the solution treatment, the aforementioned upper and lower limits of heating time can be arbitrarily combined. For example, the preferred range for heating the rolled sheet in the solution treatment may be 10 seconds or more and 300 seconds or less, 10 seconds or more and 200 seconds or less, 10 seconds or more and 120 seconds or less, 10 seconds or more and 100 seconds or less, 20 seconds or more and 80 seconds or less, or 30 seconds or more and 60 seconds or less.

[0055] In the solution treatment process, it is preferable to heat the rolled sheet using a continuous annealing line. The continuous annealing line includes a conveying device for transporting strips of rolled sheet and a heating furnace positioned along the strip's travel path, and is configured to allow continuous heating of the rolled sheet in the heating furnace. By heating the rolled sheet using a continuous annealing line, the temperature of the rolled sheet can be reliably heated to the desired temperature in a short time. As a result, the productivity of the aluminum alloy sheet can be increased, and rolled sheets with less distortion and waviness can be easily obtained.

[0056] The quenching method in solution treatment is not particularly limited and can take various forms. For example, in solution treatment, quenching can be performed by known cooling methods such as fan cooling, mist cooling, and shower cooling.

[0057] [Preliminary prescription procedures] In the above manufacturing method, a pre-aging treatment may be performed between the completion of the solution treatment and the cold rolling. In the pre-aging treatment, it is preferable to heat the rolled sheet within 10 minutes from the time when the temperature of the rolled sheet falls below 500°C in the solution treatment, under conditions that the time during which the temperature of the rolled sheet is within the range of 50°C to 140°C is 1 hour or more. By performing a pre-aging treatment under these specific conditions between the completion of the solution treatment and the cold rolling, it is possible to more reliably obtain an aluminum alloy sheet with high strength.

[0058] [Cold rolling] In the above manufacturing method, the rolled sheet after solution treatment is cold-rolled under conditions that result in a reduction ratio of 40% or more. By cold-rolling under these conditions, appropriate strain is introduced into the rolled sheet, and the strength of the aluminum alloy sheet can be improved through work hardening. If the reduction ratio in cold rolling is too low, it may lead to a decrease in the strength of the aluminum alloy sheet. From the viewpoint of further increasing the strength of the aluminum alloy sheet, a reduction ratio of 50% or more is preferable, more preferably 60% or more, even more preferably 70% or more, and particularly preferable 80% or more.

[0059] [Artificial aging treatment] In artificial aging treatment, the rolled sheet after cold rolling is heated under conditions that the temperature of the rolled sheet is within the range of 100°C to 220°C for 1 hour to 48 hours. By performing artificial aging treatment under these specific conditions, elements that are in a supersaturated solid solution in the rolled sheet can be precipitated, forming a fine β'' phase. As a result, an aluminum alloy sheet with high strength can be obtained.

[0060] From the viewpoint of more easily obtaining aluminum alloy sheets with high strength, the maximum temperature of the rolled sheet in the artificial aging treatment is preferably 110°C or higher, more preferably 120°C or higher, and even more preferably 130°C or higher. If the maximum temperature of the rolled sheet in the artificial aging treatment is too low, it becomes difficult to sufficiently precipitate the β'' phase, which may lead to a decrease in the strength of the aluminum alloy sheet.

[0061] On the other hand, if the maximum temperature of the rolled sheet during artificial aging is too high, it can lead to over-aging, which may actually reduce the strength of the aluminum alloy sheet. This problem can be easily avoided by setting the maximum temperature of the rolled sheet during artificial aging to 220°C or lower, preferably 200°C or lower, and more preferably 180°C or lower.

[0062] In determining the preferred range for the maximum temperature of the rolled sheet during artificial aging, the aforementioned upper and lower limits of the maximum temperature can be arbitrarily combined. For example, the preferred range for the maximum temperature of the rolled sheet during artificial aging may be 110°C to 220°C, 120°C to 200°C, or 130°C to 180°C. [Examples]

[0063] Examples of the aluminum alloy sheet and its manufacturing method will now be described. The aluminum alloy sheet in this example has a chemical composition containing Si: 0.40% to 1.1% by mass, Fe: 0% to 0.70% by mass, Cu: 0% to 1.1% by mass, Mg: 0.40% to 1.2% by mass, Cr: 0% to 0.35% by mass, Mn: 0% to 0.80% by mass, Zn: 0% to 0.25% by mass, and Ti: 0% to 0.15% by mass, with the remainder being Al and unavoidable impurities, a thickness of 0.1 mm to 2.5 mm, and a 0.2% yield strength of 385 MPa or more.

[0064] Furthermore, the aluminum alloy sheet in this example is obtained by preparing an ingot having the aforementioned chemical composition, performing hot rolling on the ingot when its temperature is 490°C or higher at the start of rolling, performing solution treatment on the rolled sheet obtained by hot rolling by heating it under conditions that the time the rolled sheet's temperature is in the range of 500°C to 580°C is 300 seconds or less, and then performing quenching, after which the rolled sheet is cold-rolled under conditions that the reduction ratio is 40% or higher, and performing artificial aging treatment on the cold-rolled rolled sheet by heating it under conditions that the time the rolled sheet's temperature is in the range of 100°C to 220°C is 1 hour or more and 48 hours or less.

[0065] Tables 1 to 4 show specific examples of the aluminum alloy sheets used in this example. The manufacturing methods for these aluminum alloy sheets are as follows.

[0066] (Test materials A1-A4) Test materials A1 to A4 have a chemical composition containing Si: 0.68 mass%, Fe: 0.26 mass%, Cu: 0.30 mass%, Mg: 1.02 mass%, Cr: 0.17 mass%, Mn: 0.07 mass%, Zn: 0.003 mass%, and Ti: 0.006 mass%, with the remainder being Al and unavoidable impurities. The thickness, tensile strength, 0.2% yield stress, and elongation of test materials A1 to A4 are shown in Table 1.

[0067] The methods for measuring the tensile strength, 0.2% proof stress, and elongation of the test material are as follows: First, a No. 5 test specimen, as specified in JIS Z2241:2011, is taken from each test material, with the longitudinal direction parallel to the rolling direction. A tensile test is then performed using this specimen according to the method specified in JIS Z2241:2011. The tensile strength, 0.2% proof stress, and elongation are then obtained based on the load-displacement curve obtained from the tensile test.

[0068] To prepare test materials A1 to A4, first, ingots having the aforementioned chemical composition are prepared by DC casting. Next, the ingots are heated by holding them at a temperature of 560°C for 6 hours, and then hot-rolled to produce rolled plates. The temperature of the ingot at the start of rolling is set at 540°C.

[0069] Next, cold rolling is performed to reduce the thickness of the rolled sheet to 0.75 mm. This rolled sheet is then immersed in a saltpeter bath and heated. After removing the rolled sheet from the saltpeter bath, it is immediately quenched to perform solution treatment. The maximum temperature of the rolled sheet during the solution treatment is 550°C. The heating time during the solution treatment, that is, the time from when the temperature of the rolled sheet reaches 500°C until the temperature of the rolled sheet falls below 500°C, is 25 seconds.

[0070] After solution treatment is complete, the rolled sheet is left to stand for two days in a room maintained at approximately 20°C. During this standing period, natural aging occurs, and the strength of the rolled sheet increases compared to before standing. Subsequently, the rolled sheet is cold-rolled to a reduction ratio shown in Table 1, reducing the thickness of the rolled sheet to the values ​​shown in Table 1. After cold rolling, the rolled sheet is heated in a heating furnace and subjected to artificial aging treatment to obtain test materials A1 to A4. The maximum temperature of the rolled sheet during artificial aging treatment is set at 140°C. The heating time during artificial aging treatment, that is, the time from when the temperature of the rolled sheet reaches 100°C until the temperature of the rolled sheet falls below 100°C, is set at 17 hours.

[0071] (Test materials A5~A6) Test specimens A5 to A6 have the same configuration as test specimens A1 to A4, except that they have the thickness, tensile strength, 0.2% yield strength, and elongation shown in Table 1. The method for preparing test specimens A5 to A6 is the same as that for test specimens A1 to A4, except that the thickness of the rolled sheet obtained by cold rolling after hot rolling, the period of resting of the rolled sheet after solution treatment, the thickness of the rolled sheet obtained by cold rolling after solution treatment, and the heating conditions in artificial aging treatment are changed as shown in Table 1.

[0072] (Test materials A7~A8) Test materials A7 to A8 have the same composition as test materials A5 to A6, except that they have the tensile strength, 0.2% yield strength, and elongation shown in Table 1. The method for preparing test materials A7 to A8 is the same as that for test materials A5 to A6, except that the rolled sheet after solution treatment is left to stand for 8 days in a room maintained at approximately 5°C before being cold-rolled.

[0073] (Test materials A9~A10) Test materials A9 to A10 have the same composition as test materials A5 to A6, except that they have the tensile strength, 0.2% yield strength, and elongation shown in Table 1. The method for preparing test materials A9 to A10 is the same as that for test materials A5 to A6, except that the rolled sheet after solution treatment is left to stand for 8 days in a room maintained at approximately 40°C before being cold-rolled.

[0074] (Test materials B1~B12) Test materials B1 to B12 have the same chemical composition as test materials A1 to A10. The thickness, tensile strength, 0.2% yield strength, and elongation of test materials B1 to B12 are shown in Tables 2 and 3.

[0075] To prepare test materials B1 to B12, first, ingots having the aforementioned chemical composition are prepared by DC casting. Next, the ingots are heated by holding them at a temperature of 560°C for 6 hours, and then hot-rolled to produce rolled plates. The temperature of the ingot at the start of rolling is set at 540°C.

[0076] Next, cold rolling is performed to reduce the thickness of the rolled sheet to 1.5 mm. This rolled sheet is then immersed in a saltpeter bath and heated. After removing the rolled sheet from the saltpeter bath, it is immediately quenched to perform solution treatment. The maximum temperature of the rolled sheet during the solution treatment is 550°C, and the heating time is 30 seconds.

[0077] After the solution treatment is complete, the rolled plates are heated in a heating furnace for pre-aging treatment. The maximum temperature of the rolled plates during pre-aging treatment shall be 90°C. The heating time during pre-aging treatment, that is, the time from when the temperature of the rolled plates reaches 50°C until the temperature of the rolled plates falls below 50°C, shall be 15 hours.

[0078] After the preliminary aging treatment is completed, the rolled plates are left to stand for 8 days in a room maintained at approximately 20°C. During this standing period, natural aging occurs, and the strength of the rolled plates increases compared to before standing. Subsequently, the rolled plates are cold-rolled to the reduction ratio shown in Tables 2 and 3, reducing the thickness of the rolled plates to the values ​​shown in Tables 2 and 3. After cold rolling, the rolled plates are heated under the heating conditions shown in Tables 2 and 3 to perform artificial aging treatment, thereby obtaining test materials B1 to B12.

[0079] (Test materials B13~B14) Test specimens B13 to B14 have the same composition as test specimens B1 to B2, except that they have the tensile strength, 0.2% yield strength, and elongation shown in Table 3. The method for preparing test specimens B13 to B14 is the same as that for test specimens B1 to B2, except that the rolled plates, after preliminary aging treatment, are left to stand in a room maintained at approximately 5°C for 8 days before being cold-rolled.

[0080] (Test specimens B15-B16) Test specimens B15 to B16 have the same composition as test specimens B1 to B2, except that they have the tensile strength, 0.2% yield strength, and elongation shown in Table 3. The method for preparing test specimens B15 to B16 is the same as that for test specimens B1 to B2, except that the rolled plates, after preliminary aging treatment, are left to stand in a room maintained at approximately 40°C for 8 days before being cold-rolled.

[0081] (Test materials C1~C2) Test materials C1 to C2 are test materials for comparison with test materials A1 to A10 and test materials B1 to B16. Test materials C1 to C2 have a chemical composition containing Si: 0.7 mass%, Fe: 0.37 mass%, Cu: 0.32 mass%, Mg: 1.1 mass%, Cr: 0.18 mass%, Mn: 0.06 mass%, Zn: 0.03 mass%, and Ti: 0.01 mass%, with the remainder being Al and unavoidable impurities. The thickness, tensile strength, 0.2% yield strength, and elongation of test materials C1 to C2 are shown in Table 3.

[0082] To prepare test materials C1 and C2, first, ingots having the aforementioned chemical composition are prepared by DC casting. Next, the ingots are heated by holding them at a temperature of 490°C for more than one hour, and then hot-rolled to produce rolled plates. The temperature of the ingot at the start of rolling is set at 485°C.

[0083] Next, cold rolling is performed to reduce the thickness of the rolled sheet to 3 mm. After heating the rolled sheet using a continuous annealing line, solution treatment is performed by quenching the rolled sheet at the outlet of the heating furnace of the continuous annealing line. The maximum temperature of the rolled sheet during the solution treatment is 550°C, and the heating time is 50 seconds.

[0084] After the solution treatment is complete, the rolled sheet is heated in a heating furnace for pre-aging treatment. The maximum temperature of the rolled sheet during pre-aging treatment is 80°C, and the heating time is 12 hours.

[0085] After the preliminary aging treatment is complete, the rolled plates are left to stand in a room maintained at approximately 20°C for more than one month. During this standing period, natural aging occurs, and the strength of the rolled plates increases compared to before standing. Subsequently, the rolled plates are cold-rolled to a reduction ratio of 90%, reducing the thickness of the rolled plates to 0.3 mm. After cold rolling, the rolled plates are heated under the heating conditions shown in Table 3 to perform artificial aging treatment, thereby obtaining test materials C1 to C2.

[0086] (Test materials D1~D4) Test materials D1 to D4 have a chemical composition containing Si: 0.65 mass%, Fe: 0.16 mass%, Cu: 0.80 mass%, Mg: 0.75 mass%, Cr: less than 0.01 mass%, Mn: 0.12 mass%, Zn: less than 0.01 mass%, and Ti: 0.01 mass%, with the remainder being Al and unavoidable impurities. The thickness, tensile strength, 0.2% yield stress, and elongation of test materials D1 to D4 are shown in Table 4.

[0087] To prepare test materials D1 to D4, first, ingots having the aforementioned chemical composition are prepared by DC casting. Next, the ingots are heated by holding them at a temperature of 560°C for 6 hours, and then hot-rolled to produce rolled plates. The temperature of the ingot at the start of rolling is set at 540°C.

[0088] Next, cold rolling is performed to reduce the thickness of the rolled sheet to 0.75 mm. This rolled sheet is then immersed in a saltpeter bath and heated. After removing the rolled sheet from the saltpeter bath, it is immediately quenched to perform solution treatment. The maximum temperature of the rolled sheet during the solution treatment is 550°C, and the heating time is 25 seconds.

[0089] After solution treatment is complete, the rolled sheet is left to stand for two days in a room maintained at approximately 20°C. During this standing period, natural aging occurs, and the strength of the rolled sheet increases compared to before standing. Subsequently, the rolled sheet is cold-rolled to the reduction ratio shown in Table 4, reducing the thickness of the rolled sheet to the value shown in Table 4. After cold rolling, the rolled sheet is heated in a heating furnace and subjected to artificial aging treatment to obtain test materials D1 to D4. The maximum temperature of the rolled sheet during artificial aging treatment is 140°C, and the heating time is 17 hours.

[0090] (Test materials E1~E3) Test materials E1 to E3 are for comparison with test materials D1 to D4. Test materials E1 to E3 have a chemical composition containing Si: 0.65 mass%, Fe: 0.15 mass%, Cu: 0.80 mass%, Mg: 0.75 mass%, Cr: less than 0.01 mass%, Mn: 0.12 mass%, Zn: less than 0.01 mass%, and Ti: 0.03 mass%, with the remainder being Al and unavoidable impurities. The thickness, tensile strength, 0.2% yield stress, and elongation of test materials E1 to E3 are shown in Table 4.

[0091] To prepare test materials E1 to E3, first, ingots having the aforementioned chemical composition are prepared by DC casting. Next, the ingots are subjected to homogenization treatment by holding them at a temperature of 540°C for 12 hours. After the homogenization treatment, the ingots are cooled to room temperature, and then heated by holding them at a temperature of 480°C for 3 hours. Then, hot rolling is performed on the ingots immediately after heating to produce rolled plates. The temperature of the ingots at the start of rolling is 480°C.

[0092] Next, the rolled sheet is held at 400°C for 1 hour for intermediate annealing. After intermediate annealing, the rolled sheet is cold-rolled to reduce its thickness to 1 mm. This rolled sheet is then immersed in a saltpeter bath and heated. The rolled sheet is then immediately quenched after being removed from the saltpeter bath for solution treatment. The maximum temperature of the rolled sheet during the solution treatment is 550°C, and the heating time is 30 seconds.

[0093] After solution treatment is complete, the rolled sheet is left to stand for several days in a room maintained at approximately 20°C. During this standing period, natural aging occurs, causing the strength of the rolled sheet to increase compared to before standing. Subsequently, the rolled sheet is cold-rolled to a reduction ratio shown in Table 4, reducing the thickness of the rolled sheet to the values ​​shown in Table 4. After cold rolling, the rolled sheet is heated in a furnace and subjected to artificial aging treatment to obtain test materials E1 to E3. The maximum temperature of the rolled sheet during artificial aging treatment is 180°C, and the heating time is 6 hours.

[0094] (Test materials E4~E5) Test specimens E4 to E5 are for comparison with test specimens D1 to D4. Test specimens E4 to E5 have the same configuration as test specimens E2 to E3, except that they have the thickness, tensile strength, 0.2% yield strength, and elongation shown in Table 4. The method for preparing test specimens E4 to E5 is the same as that for test specimens E2 to E3, except that the rolled plates after solution treatment are subjected to pre-aging treatment under the heating conditions shown in Table 4.

[0095] [Table 1]

[0096] [Table 2]

[0097] [Table 3]

[0098] [Table 4]

[0099] As shown in Tables 1 to 4, test materials A1 to A10, B1 to B16, and D1 to D4 were manufactured by the specified manufacturing method described above. Therefore, these test materials can be made thin while maintaining high strength. In addition, these test materials have high flatness and exhibit little waviness or distortion.

[0100] In contrast, as shown in Table 3, in the manufacturing process of test materials C1 to C2, hot rolling is performed at a temperature lower than the specified range of the ingot. Therefore, the 0.2% yield strength of test materials C1 to C2 is lower than that of test materials A1 to A10 and test materials B1 to B16.

[0101] Furthermore, as shown in Table 4, in the manufacturing process of test materials E1 to E5, the ingots are cooled to room temperature after homogenization. However, the heating temperature when the ingots are reheated is too low, resulting in the ingot temperature at the start of hot rolling being lower than the specified range. Therefore, the 0.2% yield strength of test materials E1 to E5 is lower than that of test materials A1 to A10 and test materials B1 to B16.

[0102] Although embodiments of the aluminum alloy plate and its manufacturing method have been described above based on the examples, the specific embodiments of the aluminum alloy plate and its manufacturing method according to the present invention are not limited to those of the examples, and the configuration can be appropriately modified without impairing the spirit of the present invention.

[0103] For example, the aluminum alloy plate according to the present invention may take the following embodiments: [1] to [3].

[0104] [1] Si: 0.40 mass% or more and 1.1 mass% or less, Fe: 0 mass% or more and 0.70 mass% or less, Cu: 0 mass% or more and 1.1 mass% or less, Mg: 0.40 mass% or more and 1.2 mass% or less, Cr: 0 mass% or more and 0. A chemical component containing 35% by mass or less, Mn: 0% by mass or more and 0.80% by mass or less, Zn: 0% by mass or more and 0.25% by mass or less, and Ti: 0% by mass or more and 0.15% by mass or less, with the balance consisting of Al and inevitable impurities; A thickness of 0.1 mm or more and 2.5 mm or less, An aluminum alloy plate having a 0.2% yield strength of 385 MPa or higher.

[0105] [2] The aluminum alloy plate according to [1], wherein the thickness of the aluminum alloy plate is 0.1 mm or more and less than 2.0 mm. [3] An aluminum alloy sheet as described in [1] or [2], having an elongation of 6% or more.

[0106] Furthermore, the method for manufacturing an aluminum alloy sheet according to the present invention may take the following embodiments: [4] to [7].

[0107] A method for manufacturing an aluminum alloy plate as described in any one of [4], [1] to [3], Prepare a casting having the aforementioned chemical components, Hot rolling is performed on the ingot while its temperature at the start of rolling is 490°C or higher. The rolled sheet obtained by the hot rolling is subjected to solution treatment by heating it under conditions such that the time the temperature of the rolled sheet is in the range of 500°C to 580°C is 300 seconds or less, followed by quenching. Subsequently, the rolled plate is subjected to cold rolling under conditions that result in a reduction ratio of 40% or more. A method for manufacturing an aluminum alloy sheet, comprising heating the cold-rolled sheet for an artificial aging treatment under conditions that the temperature of the sheet remains within the range of 100°C to 220°C for 1 hour to 48 hours.

[0108] [5] The method for manufacturing an aluminum alloy sheet according to [4], wherein the ingot is held at a temperature of 490°C or higher for one hour or more before hot rolling is performed. [6] The method for manufacturing an aluminum alloy sheet according to [4] or [5], wherein in the solution treatment, the rolled sheet is heated using a continuous annealing line. [7] A method for manufacturing an aluminum alloy sheet according to any one of [4] to [6], wherein, within 10 minutes from the time when the temperature of the rolled sheet falls below 500°C in the solution treatment, the rolled sheet is heated under conditions that the time during which the temperature of the rolled sheet is in the range of 50°C to 140°C is 1 hour or more, thereby performing a preliminary aging treatment, and then cold rolling is performed.

Claims

1. Si: 0.40 mass% or more and 1.1 mass% or less, Fe: 0 mass% or more and 0.70 mass% or less, Cu: 0 mass% or more and 1.1 mass% or less, Mg: 0.40 mass% or more and 1.2 mass% or less, Cr: 0 mass% or more and 0.35 mass% A chemical component containing Mn: 0 mass% or more and 0.80 mass% or less, Zn: 0 mass% or more and 0.25 mass% or less, and Ti: 0 mass% or more and 0.15 mass% or less, with the balance consisting of Al and inevitable impurities; A thickness of 0.1 mm or more and 2.5 mm or less, A 0.2% proof stress of 385 MPa or more, An aluminum alloy sheet having an elongation of 8% or more.

2. The aluminum alloy plate according to claim 1, wherein the thickness of the aluminum alloy plate is 0.1 mm or more and less than 2.0 mm.

3. Si: 0.40 mass% or more and 1.1 mass% or less, Fe: 0 mass% or more and 0.70 mass% or less, Cu: 0 mass% or more and 1.1 mass% or less, Mg: 0.40 mass% or more and 1.2 mass% or less, Cr: 0 mass% or more and 0.35 mass% A chemical component containing Mn: 0 mass% or more and 0.80 mass% or less, Zn: 0 mass% or more and 0.25 mass% or less, and Ti: 0 mass% or more and 0.15 mass% or less, with the balance consisting of Al and inevitable impurities; A thickness of 0.1 mm or more and 2.5 mm or less, A method for manufacturing an aluminum alloy sheet having a 0.2% yield strength of 385 MPa or more, A step of preparing an ingot having the aforementioned chemical components, A step of hot rolling the ingot while the temperature of the ingot at the start of rolling is 490°C or higher, The process involves heating the rolled sheet obtained by the hot rolling process under conditions that the time the temperature of the rolled sheet is within the range of 500°C to 580°C is 300 seconds or less, and then performing a quenching treatment to perform a solution treatment. Subsequently, the rolled plate is subjected to cold rolling under conditions that result in a reduction ratio of 40% or more. A method for manufacturing an aluminum alloy sheet, comprising the step of heating the cold-rolled sheet to perform artificial aging treatment under conditions that the temperature of the sheet is between 100°C and 220°C for a period of 1 hour or more and 48 hours or less.

4. A method for manufacturing an aluminum alloy sheet according to claim 3, wherein the ingot is held at a temperature of 490°C or higher for one hour or more before hot rolling is performed.

5. The method for manufacturing an aluminum alloy sheet according to claim 3, wherein the rolled sheet is heated using a continuous annealing line in the solution treatment.

6. A method for manufacturing an aluminum alloy sheet according to claim 3, wherein, within 10 minutes from the time when the temperature of the rolled sheet falls below 500°C in the solution treatment, the rolled sheet is heated under conditions that the time during which the temperature of the rolled sheet remains within the range of 50°C to 140°C is 1 hour or more, thereby performing a preliminary aging treatment, and then cold rolling is performed.

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