JPH0222446A - Manufacture of high formability aluminum alloy hard plate - Google Patents

Abstract

PURPOSE:To economically manufacture the title hard plate by subjecting an Al alloy having the specific compsn. constituted of Mn, Mg, Cu, Fe, Si, Zn and Al to specific heat treatment, hot rolling, rapid annealing and cold rolling. CONSTITUTION:An Al alloy contg., by weight, 0.5 to 2.0% Mn, 0.5 to 3.0% Mg and 0.05 to 0.50% Cu, contg. one or more kinds among 0.2 to 0.7% Fe, 0.1 to 0.5% Si and 0.05 to 1.0% Zn and the balance Al with inevitable impurities is subjected to homogenizing heat treatment at 500 to 600 deg.C form >=1hr and rolling is ended at >=280 deg.C. After that, the hot rolled plate is subjected to rapid annealing in such a manner that it is directly subjected to rapid annealing without allowed to cool or it is held under heating in the temp range of 200 to 300 deg.C for >=1hr without allowed to cool and is held at >=100 deg.C/min heating and cooling speed at 400 to 600 deg.C for <=1hr without lowering the temp. to <=150 deg.C. The Al plate is then subjected to cold rolling at <=70% final cold rolling rate. By this method, the Al hard plate having high strength, low edge rate and excellent formability can be obtd. at low cost.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing an aluminum alloy hard plate, and more specifically, a method for manufacturing an aluminum alloy hard plate that has a low selvage rate, has excellent formability, and is particularly suitable for materials such as beverage can bodies. It is related to. (Prior art) Al-Mn-Mg-based 3004 alloy hard material has been used as a material for beverage can bodies and food can bodies for beer and carbonated beverages, etc., and recent efforts have been made to reduce the weight of cans. There is a strong demand for high strength and high formability. Therefore, the present inventors first developed a precipitation hardening type can body material (hereinafter referred to as "can body").
(Japanese Patent Publication No. 7465/1986 was published in 1987), but at the same time, there is a growing demand for higher strength and higher formability. Generally, the material is hot rolled and wound into a coil shape, then annealed as is, or cold rolled and then annealed, and further cold rolled to the product thickness. Conventionally, this annealing is carried out in a batch furnace. It is said that the heating and cooling rate is around 40°C/hr and the heating temperature is maintained at around 350°C for several hours. Continuous annealing technology (CAL: annealing in which a coil is rapidly heated while unwinding, held for a short time and then cooled) using an annealing furnace has begun to be used, for example, Japanese Patent Publications No. 61-7465 and No. 62-37705. , No. 62-674Q, No. 62
-13421 etc. is proposed. However, currently the coil temperature must be low before heating. it is,
This is because in the case of aluminum material, a rubber roll is used as an essential accumulator for CAL, and the coil temperature needs to be 150° C. or lower in terms of rubber performance. Furthermore, for this purpose, the hot-rolled coil must be allowed to cool and be annealed, which is a waste of time and energy. (Problems to be Solved by the Invention) The precipitation hardening type canvas body material disclosed in the aforementioned Japanese Patent Publication No. 61-7465 has high strength and high formability, but the formability decreases due to thinning. It is necessary to further improve moldability. That is, thinning of the material leads to a decrease in drawability, stretchability, and bendability, resulting in problems in the process of molding the canvas body. Further, as mentioned above, the use of continuous annealing for the purpose of improving productivity wastes time and energy. The present invention was made in response to the demand for higher strength and higher formability, and it is possible to produce an aluminum alloy hard plate that has high strength, low selvage rate, and particularly excellent formability, and requires less time and energy. The purpose is to provide a method that can be manufactured with less waste. (Means for Solving the Problems) In order to solve the above problems, the present inventors first investigated in detail the relationship between formability and precipitates. As a result, it was found that fine precipitates formed at temperatures below 200° C. were responsible for the decline in formability. That is, what precipitates during cooling after hot rolling leads to a decrease in formability. The normal hot rolling end temperature is around 300°C, and when the cooling time was investigated, the cooling rate was 20°C/hr. At this cooling rate, it takes about 10 hours from 200°C to room temperature, which is sufficient for the formation of fine precipitates, resulting in a decrease in formability9. Confirmed that the problem needed to be resolved. On the other hand, in order to improve formability, it is necessary to start annealing at a temperature of at least 150°C or higher, but the problem at this time is the performance of the rubber roll of the accumulator. The present inventors conducted a detailed investigation regarding the rolls of the accumulator, particularly regarding the effects of heat, and found that by selecting a special steel roll and shape and considering its arrangement, it was possible to start annealing at a high temperature. In addition, since the hot rolling speed is faster than the annealing speed, we considered that it is necessary to keep the hot rolled coil warm, so we investigated various heat insulating furnaces. As a result, even simple insulated ovens, such as those without heating, can be kept sufficiently warm (in this case,
It has been confirmed that it is preferable to slightly heat the sample, preferably at a speed of ~b. Furthermore, it has been found that the precipitates that form when kept at 200 to 300°C are favorable for moldability. Based on the above knowledge, the present inventors conducted further detailed research on the adjustment of chemical components, hot rolling, annealing conditions, etc.
Here, we have invented a method for manufacturing aluminum alloy hard plates that have both excellent formability and productivity. That is, the method for manufacturing a highly formable aluminum alloy hard plate according to the present invention includes Mn: 0.5 to 2.0%, Mg: 0.5%.
~3.0% and Cu:0.05~0.50%,
Furthermore, Fe: Q, 2-0.7%, Si: 0.1-0.5%
and Zn: 0.05 to 1.0%, and the remainder is Al and inevitable impurities.
With gold alloy, subjected to homogenization heat treatment at a temperature of 500 to 600 ° C for 1 hour or more and finished hot rolling at 280 ° C or higher,
Thereafter, immediately without cooling, or without cooling, hold and heat at a temperature range of 200 to 300℃ for more than 1 hour, and then heat to 100℃/l without lowering to 150℃ or less.
10 to 400-600℃ at a heating and cooling rate of 1 lin or more
It is characterized by performing rapid annealing for less than 1 minute and then cold rolling at a finish cold rolling rate of 70%. The present invention will be explained in more detail below. First, the reason for limiting the chemical components in the present invention will be explained. Mn is effective in improving strength, and Al-Fe-Mn
It is an element that is effective in improving ironing workability by forming intermetallic compounds. However, the effect is small when O is less than 85%, and when it exceeds 2.0%, Al-'F
This is undesirable because a giant e-Mn-based intermetallic compound is formed, which impairs workability. Therefore, Mnjl is 0
．． The range is 5 to 2.0%. Like Mn, Mg is also effective in improving strength, and especially in combination with Cu, it increases A during baking during coating printing.
The strength is significantly improved by precipitation hardening of l-Cu-Mg based intermetallic compounds. However, if it is less than 0.5%, the effect will be small, and if it exceeds 3.0%, cracks will easily occur during ingot formation and hot rolling, and seizing will occur during ironing, which is not preferable. Therefore, the Mg amount is 0.5 to 3
．． The range is 0%. Cu also exhibits the same effect as Mg, and if it is less than 0.05%, the effect is small, and if it exceeds 0.50%, cracks tend to occur during ingot formation and hot rolling, and corrosion resistance also decreases. Therefore, the amount of Cu is in the range of 0.05 to 0.50%. Fe forms an Al-Fe-Mn-based intermetallic compound in combination with Mn, and is effective in improving ironing workability.
If it is less than 0.2%, the effect will be small, and if it exceeds 0.7%, a huge intermetallic compound will be formed, leading to a decrease in workability. Therefore, the amount of Fe is set in the range of 0.2 to 0.7%. Si is an element that causes a phase transformation in an Al-Fe-Mn-based intermetallic compound to form the so-called α phase of Al-Fe-Mn-3i. This α phase has high hardness and is particularly effective in improving ironing workability. However, if it is less than 0.1%, the effect is small, and if it exceeds 0.5%, edge cracking tends to occur during rolling. Therefore, the amount of Si is 0.
The range is 1% to 0.5%. Zn is effective in improving drawing and ironing processing and subsequent flange formability, but if it is less than 0.05%, the effect is small; however, if it exceeds 1.0%, there is no particular problem, but corrosion resistance may be reduced. This tends to decrease the cost and is disadvantageous in terms of cost. Therefore, the amount of Zn is 0.05 to 1.0
% range. However, it is sufficient that at least one of the above-mentioned Fe, Si, and Zn is contained. Note that impurities are permissible as long as they do not impair the effects of the present invention; for example, Cr is 0.3% or less, Ti is 0.2% or less, and Ti is 0.2% or less.
% or less, B is 0.05% or less, and Zr is 0.1% or less, there is no particular problem.Next, the manufacturing method of the present invention will be explained. The aluminum alloy having the above chemical components is melted and cast by a conventional method, and the resulting ingot is subjected to homogenization heat treatment before hot rolling, but this homogenization heat treatment must be performed at a temperature of 500° C. or higher. If the temperature is less than 5.0°C, the properties of the product (squeezing rate, moldability) will be poor, which is not preferable. Note that the holding time is not particularly limited, but the heating temperature is 550°C.
If the temperature is less than 1hr, no holding time may be required, and if the temperature is 550°C or higher, the holding time is preferably 1hr or more. In the subsequent hot rolling, the temperature at the end of rolling is particularly important, and the material properties affect the draw edge ratio. If the rolling end temperature is less than 280°C, the 0-90° lugs (cubic set! 6) formed in the subsequent annealing will be insufficient, and the formation of 45″ lugs in the subsequent cold rolling will result in poor quality in the product. It is difficult to obtain a low edge ratio.Therefore, hot rolling must be completed at a temperature of 280''C or higher. In this case, it is necessary to wind it up into a coil to carry out the next heat treatment. Note that the hot rolled plate thickness is preferably 4 m+m or less. Next, the hot rolled coil is subjected to heat treatment, which is the most distinctive feature of the present invention. That is, a coiled hot-rolled sheet (hereinafter referred to as hot coil) is wound up at 280°C or higher (usually 300 to 350°C), and is usually left to cool (or fan-cooled). In hot coils, elements dissolved in solid solution during hot rolling precipitate in a temperature range of 200° C. or lower. These precipitates are difficult to be dissolved in the subsequent heat treatment,
This leads to a decrease in formability in the product plate. Also, this cooling is a waste of heat and time. Therefore, in the present invention, heat treatment is performed without lowering the temperature of the hot coil to 200° C. or lower, or at least 150° C. or lower. In this regard, conventional and recent heat treatment furnaces have the problem that it is necessary to lower the temperature before heat treatment as described above, but in the present invention, the hot coil can be loaded into the continuous annealing furnace without lowering the temperature to 1.50°C or lower. There is no such problem because the heat treatment is carried out by heating the material continuously. To do this, you can either charge the hot coil into a continuous annealing furnace immediately without allowing it to cool after hot rolling (in this case, the temperature will not drop below 150°C), or heat the hot coil in an insulating manner without allowing it to cool down to below 150°C. It is necessary to charge the continuous annealing furnace without any damage. In the latter case, if the insulating heating temperature is 200°C or less, the moldability will be reduced as described above, and if it exceeds 300°C, relatively large precipitates will be formed, which will also promote a reduction in the moldability. Therefore, it is necessary to maintain and heat the material within a temperature range of 200 to 300° C., and the moldability can be improved by maintaining it for one hour or more. Next, rapid annealing, that is, rapid heating and cooling annealing, is performed, but if the temperature falls below 150'C when charging into the furnace, formability will deteriorate, so the temperature should be lowered to below 150°C by improving the accumulator rolls, etc. mentioned above. Annealing is performed without This rapid heating, cooling, and annealing is essential for grain refinement, productivity improvement, and precipitation hardening. A heating/cooling rate of less than 100° C./min has the opposite effect on both. Furthermore, heating at a temperature below 400°C makes recrystallization difficult in a short period of time, but heating at a temperature exceeding 600°C tends to cause burning. Furthermore, any holding time exceeding 10+++ inches is not preferred. Therefore, the final step of annealing is performed at a heating and cooling rate of 100°C/sin or higher, and at a temperature of 400°C to 60°C.
The condition is to maintain the temperature at 0°C within 10 min. Furthermore, the cooled coil is made into a product by cold rolling. This cold rolling is effective in improving strength through work hardening, but if the finishing rolling rate is less than 70%, the strength will be insufficient, so the finishing rolling rate should be 70% or more. Note that after that, stabilization annealing may be performed as necessary, and this is when extensibility is required when forming a packaging container. The annealing conditions are not particularly limited, and for example, the annealing temperature is maintained at 100 to 200°C for 1hr or more. Next, examples of the present invention will be shown. (Example) An aluminum alloy ingot having the chemical composition shown in Table 1 was subjected to homogenization heat treatment at 580°C for 6 hours, and hot rolled (two types of finishing temperatures: 250°C and 300°C target) to a plate thickness of 2.
5 mm was obtained. Thereafter, heat treatment was performed under the conditions shown in Table 2 to give a product board thickness of 0.4 mm. Note that the plate temperature was maintained for 2 hours before annealing. The resulting product was tested for rolling strength and baking (
After heating at 200° C. x 20+1 inch, the strength was examined, and the selvedge ratio and moldability were evaluated. Material properties are shown in Table 3. An Erichsen testing machine was used to measure the selvage ratio and investigate the Er value and LDR, and the selvage ratio was determined using a 33φ punch and a blank diameter of 55φ (reduction rate of 40%). The Er value was determined by Erichsen test A method. Also LDR
was determined by the following formula using a 33φ punch and varying the blank diameter. Furthermore, the bendability is 90' bending, bending radius 3R
I went there.

[Left below]

From Table 3, inventive example Nα2 has excellent formability with high strength (yield strength after baking of 28 kgf/■'' or more), low selvage (selvage ratio of 3% or less). Comparative Example No. 1, which has a low temperature, has a high selvage and has insufficient formability. Both Comparative Example No. 3, which has a high pre-annealing temperature, and Comparative Example No. 3, which has a low temperature, have insufficient formability. Also, the comparative example has a slow heating and cooling rate. Nα5 lacks strength and has low productivity. Comparative Example 6, which has a high annealing temperature, has a high selvage rate and poor formability. (Effects of the Invention) As detailed above, according to the present invention, , while properly adjusting the chemical composition of the aluminum alloy, homogenization heat treatment,
Since the conditions of hot rolling, heating before annealing, annealing, and even cold rolling are regulated in relation to each other, aluminum alloy hard plates with high strength, low sagging, and especially excellent formability can be produced without wasting time and energy. can get. Therefore, the present invention greatly contributes to reducing the weight of cans and improving the productivity of plate manufacturing.

Claims (1)

[Claims] In weight% (the same applies hereinafter), Mn: 0.5 to 2.0%, M
g: 0.5-3.0% and Cu: 0.05-0.50%
Contains Fe: 0.2 to 0.7%, Si: 0.1
0.5% and Zn: 0.05 to 1.0%, and the balance is Al and inevitable impurities. Homogenization heat treatment is performed for more than 1 hour to finish hot rolling at 280°C or more, and then, immediately without being left to cool, or without being left to cool, the product is held and heated in a temperature range of 200 to 300°C for more than 1 hour, Next, without lowering the temperature below 150℃,
400-600℃ at a heating and cooling rate of 00℃/min or more
Then, rapid annealing was performed for less than 10 minutes, and the finishing cold rolling rate was 7.
A method for producing a highly formable aluminum alloy hard plate, characterized by subjecting it to 0% cold rolling.