JP2004043939A - Method for manufacturing annealed aluminum alloy sheet superior in appearance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an annealed aluminum alloy sheet which is formed, further painted and baked if necessary, and is used as a material such as machinery and appliances, parts of home electric appliances, optical equipment, instruments and building materials, particularly the annealed aluminum alloy sheet superior in an appearance of formed parts. <P>SOLUTION: The alloy comprises one or more elements selected from among 1.5% or less Mg, 0.05-1.5% Cu, 0.05-1.5% Zn, 0.05-1.5% Mn, 0.03-0.4% Cr, 0.03-0.4% Zr, 0.03-0.4% V, 0.03-0.5% Fe and 0.005-0.2% Ti, and the balance Al with unavoidable impurities. The manufacturing method comprises rolling the above alloy into a sheet with a necessary thickness, and heating it in a continuous annealing line with a tension of 1.96 to 6.86 MPa, at a material temperature of 400 to 540°C for 3 minutes or shorter. <P>COPYRIGHT: (C)2004,JPO

Description

【００１３】
【表２】

【００１４】
【表３】

【００１５】
表３に示すように、合金Ａ１、Ａ２で本発明の焼鈍条件Ｂ１〜Ｂ３の発明例（Ｎｏ１〜３、Ｎｏ７〜９）ではいずれも完全に再結晶した焼鈍であり、小波状の模様の発生もなく良好な表面性状であった。
しかし、本発明の製造条件から外れたＢ４〜Ｂ６で作成したＮｏ４〜６、Ｎｏ１０〜１２では完全に再結晶していなかったり、表面に筋模様が現れたり、擦り疵がついたりと表面性状が良くない結果となった。
本発明の成分範囲内の合金Ａ３〜Ａ１０を本発明焼鈍条件で行った場合（Ｎｏ１３〜２０）も完全に再結晶した焼鈍材であり、表面性状も良好であった。
【００１６】
【発明の効果】
以上、詳述したように本発明例によれば、Ｍｇ１．５％以下のアルミニウム合金板においても連続焼鈍による小波状の周期的な模様の発生のない外観性能に優れたアルミニウム合金焼鈍板を製造することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an aluminum alloy annealed plate that is used as a material for various types of machinery, home appliances, optical devices, equipment, building materials, etc., which is formed and further subjected to painting baking as necessary. In particular, the present invention relates to a method for producing an annealed aluminum alloy sheet having excellent appearance performance of a molded part.
[0002]
[Prior art]
The conventional annealing method is a batch annealing method in which several coils are charged into a box type annealing furnace and heated. Heating is performed mainly by burning oil or gas, and the heating rate is 10 to 50 ° C./h. The heat annealing temperature varies depending on the alloy, but is generally from 280 to 400 ° C. In order to achieve a uniform material temperature, holding at a heating temperature is performed for about 2 to 10 hours.
In contrast, a continuous annealing method in which a coil is passed through a furnace while being unwound and heated and annealed has become common. There are various heating methods, such as a method using combustion gas, a method using electromagnetic induction heating, and a method combining these two methods. The heating speed varies slightly depending on the heating method and the plate thickness, but is several degrees C to several hundred degrees / s. In addition, the heat annealing temperature is higher than that of batch annealing and is performed at 400 ° C. or higher because the holding time is short. The holding time at the heating temperature is generally within 3 minutes. In some cases, the holding time is not taken to increase the productivity, and cooling is performed immediately after the temperature is raised to the heating annealing temperature (holding time 0 s).
As described above, the continuous annealing has a feature that the heating rate is faster than the batch annealing, and the processing time per one coil is short, and the number of production days corresponding to the kanban method can be reduced.
[0003]
[Problems to be solved by the invention]
When annealed material used for forming (referred to as O material in JIS) is produced in a continuous annealing line, the material has a small wave-like pattern with a certain periodicity at right angles to the rolling direction depending on the alloy and annealing conditions. May occur. This pattern remains even after forming processing, and may become more clearly visible by painting, and when such a pattern appears, the commercial value decreases and the user needs improvement. .
Further, as the appearance quality of the molded article, in addition to the small wavy pattern, a surface appearance property that does not generate a Ruder's mark or other various patterns on the surface during molding is required.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing an aluminum alloy sheet for forming and processing having excellent appearance performance without a small wavy pattern on the sheet surface.
[0004]
[Means for Solving the Problems]
As a result of repeated experiments and studies by the present inventors to solve the above-mentioned problems, it was found that the above-mentioned problems can be solved by appropriately controlling the furnace operating conditions in the continuous annealing line during the plate manufacturing process. Heading, this led to the invention.
[0005]
More specifically, the method for manufacturing an aluminum alloy plate of the present invention requires an alloy comprising 1.5% or less (mass%, the same applies hereinafter) of Mg and the balance of Al and unavoidable impurities. Appearance performance characterized by performing a heat treatment on a rolled sheet having a thickness of 1.96 to 6.86 MPa in a continuous annealing line at a material temperature of 400 ° C. to 540 ° C. for 3 minutes or less. This is a method for producing an aluminum alloy annealed plate excellent in quality.
Further, as described in claim 2, Mg 1.5% or less, Cu 0.05-1.5%, Zn 0.05-1.5%, Mn 0.05-1.5%, Cr 0.03-0.4% , Zr 0.03 to 0.4%, V 0.03 to 0.4%, Fe 0.03 to 0.5%, and Ti 0.005 to 0.2%. Then, for a rolled plate having a required thickness, an alloy consisting of Al and unavoidable impurities with a balance of 1.96 to 6.86 MPa in a continuous annealing line and a material temperature of 400 ° C. to 540 ° C. This is a method for producing an aluminum alloy annealed sheet having excellent surface properties, wherein a heat treatment is performed within 3 minutes.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
First, the reasons for limiting the composition of the alloy of the present invention will be described.
Mg:
If the content of Mg exceeds 1.5%, no streak-like surface defects along the sheet width direction are observed in the continuous annealing line. Therefore, the object of the present invention is to set the Mg content to 1.5% or less.
[0007]
Cu, Zn, Mn, Cr, Zr, V, Ti, Fe:
One or more of these can be added as needed to improve the strength.
Cu is added to improve strength and formability. If the Cu content is less than 0.05%, the above effect is insufficient. On the other hand, when Cu exceeds 1.5%, bending workability and corrosion resistance are reduced. Therefore, when Cu is added, the content is set to 0.05 to 1.5%.
Zn is an element that contributes to the strength improvement through the improvement of the aging property of the alloy. If its content is less than 0.05%, the above effects are insufficient, while if it exceeds 1.5%, the formability decreases. . Therefore, when Zn is added, the amount of Zn is set in the range of 0.05 to 1.5%.
Further, Mn, Cr, Zr, and V are all elements that are effective in improving strength, refining crystal grains, and stabilizing the structure. If Mn is less than 0.05%, the above effects cannot be sufficiently obtained. Further, even if Cr, Zr, and V are less than 0.03%, the above effects cannot be sufficiently obtained. On the other hand, if Mn exceeds 1.5% and Cr, Zr, and V exceed 0.4%, not only the above effects are saturated, but also a giant intermetallic compound may be generated to adversely affect the formability. Mn was in the range of 0.05 to 1.5%, and Cr, Zr, and V were all in the range of 0.03 to 0.4%.
Ti is also an element effective for improving the strength and refining the ingot structure. When the content is less than 0.005%, a sufficient effect cannot be obtained. On the other hand, when the content exceeds 0.2%, the effect of Ti addition is not obtained. In addition to being saturated, there is a possibility that a giant crystal may be generated. Therefore, Ti is set in the range of 0.005 to 0.2%.
Further, Fe is also an element effective for improving strength and refining crystal grains. If its content is less than 0.03%, a sufficient effect cannot be obtained, while if it exceeds 0.5%, formability may be reduced. Therefore, Fe was set in the range of 0.03 to 0.5%.
Note that the ranges of Zn, Mn, Cr, Zr, V, Ti, and Fe are shown in the case where these elements are included as positively added elements, and in each case, the amount of impurities smaller than the lower limit is set as the impurity. There is no particular hindrance to the inclusion. In particular, Fe of less than 0.03% is usually inevitably contained when ordinary aluminum ingots are used.
[0008]
In addition to the above elements, Al and unavoidable impurities may be basically used. Si is an unavoidable impurity element and has no particular effect if it is 0.3% or less. In general, B may be added simultaneously with the above-mentioned Ti for refining the crystal grains. The following B is allowed to be added.
Be is an element generally used in Mg-containing alloys and has an effect of preventing oxidation of molten metal. If necessary, the content can be 0.1 ppm or more and 50 ppm or less.
[0009]
Next, the manufacturing process in the method of the present invention will be described.
The process up to the continuous annealing line, that is, the process up to a rolled plate having a required product thickness may be the same as the conventional general process.
That is, casting may be performed by a DC casting method or the like, strip casting may be performed to a thickness of 2 to 10 mm by continuous casting, or block-type continuous casting may be performed to a thickness of 10 to 100 mm.
Thereafter, homogenization treatment is performed as necessary by a conventional method, and hot rolling and cold rolling may be performed to a required thickness, and between hot rolling and cold rolling, or in the middle of cold rolling. In step, intermediate annealing may be performed as necessary.
[0010]
After the required product thickness is obtained as described above, final annealing is performed using a continuous annealing line.
The annealing heating temperature is 400 to 540 ° C. If the temperature is lower than 400 ° C., recrystallization may not be performed completely. On the other hand, when annealing is performed at a temperature exceeding 540 ° C., a surface streak pattern is generated along the width direction.
The holding time is within 3 minutes. What is necessary is just to complete the recrystallization completely, and the shortest possible time is preferable. Even if it is performed for more than 3 minutes, it is useless in terms of energy, and crystal grains tend to grow, and surface defects such as rough skin are likely to occur. If the recrystallization is completed completely, depending on the heating temperature, cooling may be performed immediately after reaching the heating temperature without holding.
The furnace tension of the plate is 1.96 to 6.86 MPa. Materials with less than 1.5% Mg have low high-temperature strength, soften locally by heating in the continuous annealing line, and locally elongate periodically under the influence of tension, line speed, etc. A small wavy line pattern is generated along the line. However, by setting the tension in the range of 1.96 to 6.86 MPa under the annealing condition of heating at 400 to 540 ° C. for 3 minutes or less, it is possible to suppress the occurrence of this periodic local elongation. If the pressure is less than 1.96 MPa, the plate will sag during running on a line, causing scratches and meandering. When a tension is applied above 6.86 MPa, a failure such as elongation and breakage, or a failure in which the thickness is reduced or the width is reduced without breaking easily occurs.
The speed at which the plate is passed depends on the temperature in the furnace, the heating temperature of the plate, and the holding time, but if it is usually 10 m / min to 200 m / min, there is no particular effect on the streak pattern.
[0011]
【Example】
Hereinafter, the effectiveness of the method of the present invention will be described in detail with reference to examples.
The alloys of the alloy symbols A1 to A10 within the composition range of the present invention shown in Table 1 were cast, hot-rolled, and then cold-rolled according to the usual methods to obtain rolled plates having a thickness of 1 mm. Next, the continuous annealing line conditions were changed for each rolled sheet, and the sheet was annealed by heating, cooled, and then examined for the streak pattern in the width direction of the coil surface and the degree of recrystallization. Table 2 shows the continuous annealing line conditions for heat annealing.
As the streak pattern observation, the annealed plate was placed on a flat table, the surface was lightly ground with a grindstone and investigated for small wavy periodic streak patterns along the width direction. . The degree of recrystallization was evaluated by observing the crystal grains of the cross section, and was evaluated as れ ば when complete recrystallization was completed, and as × when unrecrystallized portions remained. In addition, the presence or absence of other surface defects such as flaws was visually observed. Table 3 shows the results.
[0012]
[Table 1]

[0013]
[Table 2]

[0014]
[Table 3]

[0015]
As shown in Table 3, all the alloys A1 and A2 were completely recrystallized in the invention examples (Nos. 1 to 3 and Nos. 7 to 9) of the annealing conditions B1 to B3 of the present invention, and a small wavy pattern was generated. There were no good surface properties.
However, in Nos. 4 to 6 and Nos. 10 to 12 prepared in B4 to B6 which deviated from the production conditions of the present invention, the surface properties were not completely recrystallized, streaks appeared on the surface, and scratches were formed. The result was not good.
When alloys A3 to A10 within the component range of the present invention were subjected to the annealing conditions of the present invention (Nos. 13 to 20), the alloys were completely recrystallized annealed materials and had good surface properties.
[0016]
【The invention's effect】
As described above in detail, according to the example of the present invention, an aluminum alloy annealed sheet excellent in appearance performance without generation of small rippled periodic patterns due to continuous annealing even in an aluminum alloy sheet of 1.5% or less of Mg is manufactured. can do.

Claims (2)

Mg is 1.5% or less (mass%, the same applies hereinafter), and the balance is made of an alloy comprising Al and unavoidable impurities to a rolled sheet having a necessary thickness. The tension is 1.96 to 6.86 MPa in a continuous annealing line. A method for producing an aluminum alloy annealed sheet having excellent appearance performance, wherein a heat treatment is performed at a temperature of 400 ° C. to 540 ° C. for 3 minutes or less. Mg 1.5% or less, Cu 0.05-1.5%, Zn 0.05-1.5%, ΔMn 0.05-1.5%, Cr 0.03-0.4%, Zr 0.03-0.4% , V 0.03 to 0.4%, Fe 0.03 to 0.5%, Ti 0.005 to 0.2%, the balance being Al and unavoidable impurities. It is characterized in that a rolled plate having a required thickness of a rolled alloy is subjected to a heat treatment in a continuous annealing line at a tension of 1.96 to 6.86 MPa and a material temperature of 400 ° C to 540 ° C for 3 minutes or less. A method for producing an aluminum alloy annealed sheet having excellent surface properties.