JPS6362836A - Aluminum-alloy rolled sheet combining high strength with heat resistance and production thereof - Google Patents

Abstract

PURPOSE:To manufacture, at a low cost, an Al-alloy rolled sheet having high strength and heat resistance in which fine intermetallic compounds are crystallized out, by subjecting a molten Al alloy having a specific composition consisting of Mg, Mn, and Al to continuous casting rolling to proper thickness and further to cold rolling. CONSTITUTION:The molten Al alloy which has a composition consisting of, by weight, 0.10-5.0% Mg, 0.3-3.0% Mn, and the balance Al with inevitable impurities and further containing, if necessary, 0.01-0.30% Zr is cast into a plate of 3-15mm thickness by means of continuous casting rolling in which rolling is carried out simultaneously with cooling and solidification by means of a couple of rotating cooling rolls for casting, etc. Subsequently, the above rolled plate is subjected to cold rolling to the final thickness, so that rolled sheet in which maximum length of the crystallized matter of intermetallic com pound at the sheet surface is regulated to <=10mum can be obtained. The above Al-alloy rolled sheet has high strength and, moreover, it is minimal in deteriora tion in yield strength even if subjected to baking treatment at a temp. as high as >=about 300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is suitable for applications where a baked coating such as enamel baking or resin baking is applied. The present invention relates to a plate and a method for manufacturing the same.

Conventional technology Generally, when aluminum alloy materials are exposed to high temperatures,
It is known that recovery and recrystallization occur, resulting in a significant decrease in strength. For example, in applications where an aluminum plate is used with a baked coating such as enamel baking or resin baking, the core aluminum plate is annealed during the baking process, reducing the mechanical strength of the final product. For such applications, it is generally necessary to use thick-walled materials having a considerable thickness.

Conventionally, as an aluminum alloy material suitable for use at high temperatures, a high Mn-based 1'-Mn alloy containing Mn in a eutectic composition (1.4% Mn) or more is known. However, even if such a high Mn-based Al-Mn alloy is used,
If heated to a high temperature exceeding 300'C, the yield strength will often drop to below 10Kqf/- even if the heating time is short, therefore, especially when heated to a high temperature such as enamel baking, It was unsuitable for such uses, and its strength was still insufficient.

On the other hand, in Japanese Patent Publication No. 56-11747, 2-
A heat-resistant aluminum alloy plate manufactured from an Aid-Mn alloy containing 2.6% Mn by continuous casting and rolling, and further cold-rolled to exhibit good heat resistance even at temperatures of 300°C or higher. A manufacturing method has been proposed. However, in the case of this proposed method, a significant improvement in heat resistance cannot be expected unless Fe and Si, which are unavoidably contained as impurity elements, are controlled to 0.1% or less each. It is necessary to use a metal with high purity as the melting material, resulting in high costs and insufficient strength.

Problems to be Solved by the Invention As mentioned above, conventional high-Mn Al-Mn alloys still have insufficient heat resistance and strength, and as proposed above, the continuous casting and rolling method is applied. Al-M
In the method for manufacturing n-based alloy plates, Fe5Si must be regulated to 0.1% or less, resulting in high costs and insufficient strength.

This invention was made against the background of the above-mentioned circumstances, and has higher heat resistance and strength than conventional high-Mn-based Al-Mn alloys, and is superior at low cost without restricting Fe or 3i to 0.51% or less. The object of the present invention is to provide an aluminum alloy rolled plate that has improved heat resistance and high strength by 1q, and a method for manufacturing the same.

Means for Solving the Problems The aluminum alloy rolled plate of the first invention has Mg0.10 to
5.0% and Mn 0.3 to 3.0%, the remainder consists of Al and inevitable impurities, and the maximum length of intermetallic compound crystallization on the plate surface is 10 μm or less. It is something to do.

Further, the aluminum alloy rolled plate of the second invention has MCI 0
．． 10-5.0%, Mn0.3-3.0% and Zr
Contains 0.01-0.30%, the balance is 8! and unavoidable impurities, and is characterized in that the maximum length of intermetallic compound crystallization on the plate surface is 10 pm or less.

Furthermore, a third invention is a method for manufacturing the aluminum alloy rolled sheet of the first invention, which comprises Mgo, io~5.0% and M
A molten aluminum alloy containing 0.3 to 3.0% of aluminum and the remainder consisting of Al and unavoidable impurities is cast into a plate with a thickness of 3 to 15 sheets by continuous casting and rolling, and then cold rolled. The method is characterized in that a rolled sheet is obtained in which the maximum length of crystallized intermetallic compounds on the surface of the sheet is iopm or less.

Further, a fourth invention is a method for manufacturing the aluminum alloy rolled plate of the second invention, comprising: Mgo, io~5.0%, M
A molten aluminum alloy containing 0.3 to 3.0% of n and 0.01 to 0.30% of zr, with the remainder being all and unavoidable impurities, was continuously cast and rolled to a plate thickness of 3.
The method is characterized in that it is cast into a plate of 15 to 15 mm and further subjected to cold rolling to obtain a rolled plate in which the maximum length of intermetallic compound crystallization on the plate surface is 10 μm or less.

Function First, the reason for limiting the components of the rolled aluminum alloy plate of the present invention will be explained.

Mq: Mg is an effective element for improving the strength of rolled plates, but at 0.1
If it is less than 0%, the effect of improving strength will be small. On the other hand, if Mg is contained in an amount exceeding 5.0%, production by continuous casting and rolling becomes difficult. Therefore, the Mg content is o, io ~ 5.0
It was set within the range of %.

Mn: Mn is an element effective in improving the strength and heat resistance of a rolled plate, but if it is less than 0.3%, a sufficient effect of improving heat resistance cannot be obtained. On the other hand, if Mn is contained in excess of 3.0%,
Manufacturing by continuous casting and rolling becomes difficult. Therefore, the Mn content was set within the range of 0.3 to 3.0%.

Zr: Zr is an element that is extremely effective in improving heat resistance, and therefore it was specifically added in the second invention. Zr is 0
．． If the content is less than 0.01%, the effect will be small, while if the content exceeds 0.30%, coarse compounds will be produced, resulting in deterioration of the surface quality of the rolled plate and non-uniform mechanical properties. The Zr content in the second invention and the fourth invention was within the range of 0.01 to 0.30%.

In addition to the above-mentioned components, industrial aluminum alloys inevitably contain Fe and Si, but if each of these is about 0.5% or less, there will be little adverse effect on heat resistance.

Furthermore, in general aluminum alloys, Ti and/or B are often added to refine the crystal grains of the ingot, but in the case of the present invention, T1 and/or B may also be added as necessary. In that case, if the Ti content is 0.10% or less and 30.002% or less is teared, there will be no adverse effect on the heat resistance.

Furthermore, in order to improve strength and heat resistance, it may contain 25% or less of Oro, and 0.20% or less of V, if necessary. Furthermore, B e ioppm or less may be added as necessary to prevent oxidation of the molten metal.

In the aluminum alloy rolled sheet of the present invention, it is necessary not only to have the above-mentioned composition, but also to have a maximum length of intermetallic compound crystallization on the surface of the final rolled sheet of 10JJIT1 or less. In this way, by regulating the maximum length of the crystallized material to 10 pm or less, excellent heat resistance can be obtained.On the other hand, if the crystallized material exceeds 10 .mu.m, sufficient heat resistance cannot be obtained. Note that the size of intermetallic compound crystallization in the final rolled plate is 10 pm.
In order to reduce the thickness to below, continuous casting and rolling is applied at the casting stage to reduce the plate thickness from 3 to 15t11!, as will be described later. It is effective to directly cast onto a plate of n and increase the solidification rate.

Next, a method for manufacturing an aluminum alloy rolled plate as described above,
That is, the third invention and the fourth invention of the present application will be explained.

In this manufacturing method, first, in casting a molten aluminum alloy having the above-mentioned composition, a plate having a thickness of 3 to 15# is manufactured by continuous casting and rolling. A specific method is to introduce molten aluminum alloy through a nozzle between a mold consisting of a pair of rotating casting rolls or a running casting belt that are cooled from the inside. What is necessary is to apply a method in which rolling is performed while cooling and solidifying the material at the same time. Here, the casting speed in continuous casting and rolling is 600 to 1500 m/n+
In, the temperature of the molten metal during casting is suitably within the range of 680 to 720°C.

In continuous casting and rolling into a plate having a wall thickness of 3 to 15 mm as described above, the cooling rate is much higher than in the case of semi-continuous casting of 200 to 15 mm. Therefore, the solid solution gap of Mn, which is advantageous for improving heat resistance, becomes larger due to the rapid solidification effect, and the size of crystallized substances during solidification becomes significantly smaller, thereby providing excellent heat resistance. On the other hand, in semi-continuous casting, even if a large amount of Mn is added, it is not sufficiently dissolved and crystallizes as an intermetallic compound during solidification. The heat resistance is poor. When the present inventors investigated the relationship between the maximum size of crystallized products and heat resistance, it was found that good heat resistance can be obtained if the maximum size of crystallized products is 1 opm or less. Therefore, the cooling rate in continuous casting and rolling should be determined so that the maximum size of crystallized substances on the surface of the final rolled plate is 10 pm or less, but usually the maximum size is regulated to 200 to 10 pm or less as described above. Is possible.

In continuous casting and rolling, if the thickness of the cast plate is less than 3 m, the casting itself will be difficult, whereas if it exceeds 15 m, the cooling rate will increase, the amount of solid solution of Mn will decrease, and the maximum size of crystallized matter in the final rolled plate will be 10 μm or less. It becomes difficult to regulate the heat resistance, and there is a possibility that the desired heat resistance cannot be obtained. Therefore, the thickness of the cast plate in continuous casting and rolling is 3
It was set within the range of ~15m.

The plate thickness obtained by continuous casting and rolling as described above is 3~
The 15 m plate-shaped ingot is cold rolled to the final thickness. During this cold rolling, the plate-shaped ingot before rolling or the plate in the middle of rolling is heated to a temperature within the range of 350 to 550°C in order to improve rollability or heat resistance against rapid baking. Intermediate annealing may be performed.

Examples [Example 1] Aluminum alloys having the five types of component compositions shown in Table 1 were cast by the methods shown in Table 1, respectively. With continuous casting and rolling, the diameter is 400rwn and the width is 300#! I
A plate-shaped ingot with a plate thickness of 8#i#I was obtained using a casting W4 roll having a water-cooled interior. On the other hand, for comparison, in semi-continuous casting and hot rolling, the cross-sectional dimensions were 500am x 1300mm.
m slab at a casting speed of 50rrI! 11/ll1lr
11 was cast at 700° C., and then heated to 500° C. and hot rolled to obtain a hot rolled sheet with a thickness of 651I11. The plate-shaped ingot or hot-rolled plate having a plate thickness of 6IIIR thus obtained was cold rolled to finally form a rolled plate having a plate thickness of 0.6#.

For each rolled plate with a thickness of 0.6 m, at 300°C and 35
Table 2 shows the results of annealing at various temperatures of 0°C, 400°C, and 450°C for 2 hours each and measuring the yield strength. Also, the plate thickness is 0.
Table 2 also shows the results of examining the maximum size of crystallized substances on the surface of a 6 m long rolled plate.

Chapter 1 Table Table 2 Note: l in the table! i degree ('C) indicates tA cold water temperature.

As is clear from Table 2, for aluminum alloys within the composition range of the first invention, the maximum size of intermetallic compound crystallization in the final rolled plate was 5 μm when continuous casting and rolling was applied.
It is clear that under manufacturing conditions Nα1 and No. 2, both exhibit high yield strength even after annealing at 300 to 450°C, and have high strength and excellent heat resistance. On the other hand, the alloy used under manufacturing condition Nα3 does not contain M(7), and in this case, it has better heat resistance compared to manufacturing conditions Nα4 and Nα5, but the strength before annealing, that is, as rolled, is higher than that under manufacturing conditions Nα4 and Nα5. Since the strength of N is lower than that with Mg added,
The strength after annealing is also lower compared to α1 and Company 2. Further, the alloy used under the manufacturing condition Nα4 did not contain Mn, and in this case only extremely low strength was obtained. Furthermore, for manufacturing condition Nα5, although the alloy composition is within the range of the first invention, the maximum crystallized size increases due to the application of semi-continuous casting and hot rolling, and therefore sufficient heat resistance and strength cannot be obtained. Ta.

[Example 2] Aluminum alloys having the four component compositions shown in Table 3 were cast by the methods shown in Table 3, respectively. The detailed conditions for each method are the same as in Example 1.

The plate-shaped ingot or hot-rolled plate having a thickness of 6M thus obtained was cold rolled to finally form a rolled plate having a thickness of 0.6m.

For each rolled plate with a plate thickness of 0.6 mm, at 300°C, 35
Table 4 shows the results of annealing at various temperatures of 0° C., 400° C., and 450° C. for 2 hours each and measuring the yield strength. Also, the plate thickness is 0.
Table 4 also shows the results of investigating the maximum size of crystallized substances on the surface of a 6 m long rolled plate.

Table 3 Table 4 Note 2: The temperature ('C) in the table indicates the annealing temperature.

As is clear from Table 4, for the aluminum alloy within the composition range of the second invention, the manufacturing condition NQ6 was applied where continuous casting and rolling was applied and the maximum size of the intermetallic compound material in the final rolled sheet was 8 μm. It is clear that the case shows high yield strength even after annealing at 300 to 1150°C, and has excellent strength and heat resistance. On the other hand, the alloy used under manufacturing condition Nα7 is one without Mn addition, and in this case, even if continuous casting and rolling is applied and the maximum size of crystallized particles is ioμm or less, the yield strength is increased by heating at 300 to 450°C. The strength and heat resistance decreased significantly, and sufficient strength and heat resistance could not be obtained. In addition, since the alloy used under the manufacturing condition Nα8 does not have Mg added, its strength before annealing, that is, the strength as rolled, is lower than that with Mg added, and therefore the strength after annealing is also lower than that of Nα6. It became low. In addition, the manufacturing condition Nα9 is
Although the alloy composition was within the range of the second invention, the application of semi-continuous casting and hot rolling increased the maximum size of crystallized particles, and therefore sufficient heat resistance and strength could not be obtained.

Effects of the Invention As is clear from the above explanation, according to the present invention, an aluminum alloy rolled sheet is obtained which has high strength and excellent heat resistance with little decrease in yield strength even when heated to a high temperature of 300° C. or higher. Moreover, since excellent heat resistance and high strength can be obtained without restricting the content of FeJcJst contained as an unavoidable impurity to a very small amount, there is no fear that the metal cost will increase.

Note that the aluminum alloy rolled plate according to the present invention has a
It is ideal for applications that involve baking at high temperatures of 0°C or higher, but
Of course, it can be used for blinds and colored aluminum building materials that are baked at temperatures below 300℃, and can also be used for structural materials around engines, pumps, and heating elements that are relatively hot. can.

Claims (4)

[Claims] (1) Contains 0.10 to 5.0% Mg (wt%, same hereinafter) and 0.3 to 3.0% Mn, with the remainder consisting of Al and inevitable impurities, and intermetallic compounds crystallize on the plate surface. A high-strength heat-resistant rolled aluminum alloy plate, characterized in that the maximum length of the object is 10 μm or less. (2) Mg0.10-5.0%, Mn0.3-3.0%
and 0.01 to 0.30% of Zr, with the remainder being Al.
and unavoidable impurities, and furthermore, the maximum length of intermetallic compound crystallization on the plate surface is 10 μm or less. (3) Mg0.10-5.0% and Mn0.3-3.
A molten aluminum alloy containing 0% Al and the remainder consisting of Al and unavoidable impurities is cast into a plate with a thickness of 3 to 15 mm by continuous casting and rolling, and then cold rolled to improve the surface of the plate. Maximum length of crystallized intermetallic compound is 10μ
A method for producing a high-strength, heat-resistant aluminum alloy rolled plate, the method comprising obtaining a rolled plate having a thickness of less than m. (4) Mg0.10-5.0%, Mn0.3-3.0%
and 0.01 to 0.30% of Zr, with the remainder being Al.
The molten aluminum alloy containing aluminum and inevitable impurities is cast into a plate with a thickness of 3 to 15 mm by continuous casting and rolling, and then cold rolled to maximize the crystallization of intermetallic compounds on the plate surface. A method for producing a high-strength, heat-resistant aluminum alloy rolled plate, the method comprising obtaining a rolled plate having a length of 10 μm or less.