JPH02270930A - Aluminum alloy hard sheet having excellent formability and its manufacture - Google Patents

Abstract

PURPOSE:To obtain the high strength, high formability Al alloy hard sheet capable of thinning an entire can even if the componential range of Fe and Mn is widen by specifying the compsn. of an Al alloy, particularly the amounts of Fe and Mn having high influence and its manufacturing conditions. CONSTITUTION:An Al alloy ingot contg., by weight, 0.5 to 1.0% Mn, 0.5 to 1.2% Fe and 0.5 to 2.0% Mg so that Mn and Fe satisfy (Fe+1.07XMn)<1.81, furthermore contg. one or more kinds among 0.1 to 0.7% Si, 0.05 to 0.5% Cu and 0.05 to 1.0% Zn and the balance Al is used. The ingot is subjected to homogenizing heat treatment at 500 to 600 deg.C, is thereafter hot-rolled at 1.5 to 2.5mm end sheet thickness at >=280 deg.C end temp. After that, the alloy is subjected to process annealing under the conditions of >=100 deg.C/min heating-cooling rate and 400 to 600 deg.C arrival temp. and is subjected to final cold rolling at >=80% rolling reduction.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an aluminum alloy hard plate, and more specifically, 1. For example, in beverage can body materials, an aluminum alloy that has excellent formability (neck and flange), especially after full packaging and printing (baking). This article relates to hard plates and their manufacturing methods. (Prior Art) Al-Mn-Mg based 3004 alloy hard plates have been used as a material for beverage can bodies such as beer and carbonated beverages and food can bodies. However, in recent years, in order to reduce the weight of cans, there has been an increasing demand for high strength and high formability. Therefore, the present inventors have previously developed a precipitation-hardening type high-strength aluminum material for can bodies (Japanese Patent Publication No. 7465/1983, etc.), and the enhancement of the strength of this material was mainly achieved by thinning the can bottom. Contributing. However, when considering further weight reduction of the can, it becomes necessary to reduce the thickness of the entire can body. Therefore, in order to further reduce the weight of can bodies in the future, materials that can make can walls thinner will be needed, and such demands are becoming stronger. On the other hand, regarding the manufacturing method of can material, there are 30
04 alloy ingots are subjected to a combination of homogenization heat treatment, hot rolling, cold rolling, and intermediate annealing, but recently, continuous annealing furnaces have been used to increase the strength of the material and improve productivity. (CAL; short-time annealing in which the coil is rapidly heated and cooled while unwinding) has begun to be used, for example, Japanese Patent Publications No. 61-7465, No. 62-37705,
No. 62-6740, No. 62-13421, etc. have been proposed. By the way, 3004 alloy is established as having a component range shown in Table 1 in the JIS standard, and the component range in practical use is as shown in the lower row. Table 1 (%) (Continued from Table 1) 3004 alloy has been widely used since it has relatively high strength and is excellent in DI (drawing and ironing) processability, which is the method used to form can bodies. In particular, the key point of the 3004 alloy is that Al-Mn-Fe crystals, which have excellent ironing workability, are appropriately distributed.
At present, e and Mn are regulated within a narrow range, and Il is produced. (Problem to be solved by the invention) As mentioned earlier, to reduce the weight of the can body, it is necessary to reduce the thickness of the entire can body, and with the conventional technology, it is possible to reduce the thickness of only the bottom of the can by using a high-strength material. 6 However, increasing the strength of the material also leads to increasing the strength of the can wall, which has a positive effect on the axial buckling strength of the can required during filling. This is a negative factor for flange processing, and inevitably makes it difficult to reduce the thickness of the can wall, particularly at the neck and flange portions. Furthermore, one of the reasons why it is difficult to reduce the thickness of the can wall is that it is necessary to properly distribute the Al-Fa-Mn system crystallized substances as mentioned above, and for Fa and Mn, JIS
Although the range of ingredients in the standards and prior patents is wide, other ingredients (
Mg, Cu, etc.] from the viewpoint of strength, formability, and formation of giant crystallized substances. In practical terms, there was a constraint that it had to be controlled within a small area. The present invention eliminates the drawbacks of the above-mentioned prior art and provides Fe and Mn
The object of the present invention is to provide a high-strength, high-formability aluminum alloy hard plate that makes it possible to reduce the thickness of the entire can body even if the range of components is widened, and a method for manufacturing the same. <Means for Solving Problem M) In view of the above-mentioned problems, the present inventors conducted a detailed investigation on the effects of component composition and manufacturing conditions on the strength and crystallized material distribution of the can body. the result. In both cases, Fe and Mn have a large influence, and the above problems have been solved by optimizing the component composition and manufacturing conditions. In other words, for reducing the strength of the can wall, Al-Fe-M
By adjusting the components so that the n-type crystallized substances are relatively large and dispersed in a large amount, softening after baking (reduction in can wall strength) can be increased. However, in order to suppress the production of large products, it is necessary to appropriately control the amounts of Fe and Mn. Furthermore, we have found that increasing the strength of the can bottom (increasing the strength of the material) can be achieved by optimizing the manufacturing conditions (especially hot rolling, cold rolling, intermediate annealing), and hereby we have developed the present invention. This is what was done. That is, in the present invention, Mn: 0.5 to 1.0%, Fe:
0.5-1.2% and Mg: 0.5-2.0%, Mn
and Fe is Fe+1. Contains so as to satisfy the relationship O7XMn<1.81%, and further contains Si: 0.1 to 0.7%, C
u: 0.05~0.5% and Zn: 0.05~1°0%
The object of the present invention is to provide an aluminum alloy hard plate with excellent formability, which is characterized by containing one or more of the above, with the remainder consisting of A, Q and unavoidable impurities. In addition, the method for manufacturing such aluminum alloy hard plates involves subjecting Af1 alloy ingots having the above chemical components to homogenization heat treatment at a temperature of 500 to 600°C, then hot rolling, and plate thickness 1.
．． 5-2, 5 mm, done at a finishing temperature of 280°C or higher,
After that, intermediate annealing is performed at a heating and cooling rate of 100℃/+++in
The above is characterized in that the final cold rolling is carried out at a final temperature of 400 to 6 oO<0>C and a rolling reduction of 80% or more. The present invention will be explained in more detail below. (Function) First, the reasons for limiting the chemical components in the present invention are as follows. Mn: Mn is an element that is effective in improving strength, improving ironing workability by properly forming Al-Fe-Mn products, and softening can wall strength. However, if it is less than 0.5%, both effects are small, and if it exceeds 1-00%, the strength is too high, resulting in a decrease in formability, and furthermore, due to the relationship with the Fe content, the Al2-Fe-Mn-based giant This is not preferable because it causes processing defects due to the formation of crystallized substances. Therefore, the amount of Mn is 0
．． The range is 5 to 1.0%. Fe: In relation to Mn, Fe is an element that is effective in improving ironing workability and softening the can wall strength by properly forming Al-Fe-Mn products. However, if it is less than 0.5%, the effect on softening the can wall strength is small, and if it exceeds 1.2%, it is not preferable because it forms giant pieces and causes processing defects. Therefore, the amount of Fe is set in the range of 0.5 to 1.2%. However, Mn and Fe are elements that greatly participate in the formation of giant crystallized substances, and detailed research by the present inventors revealed that Fe+1
．． It has become clear that when the value of O7XMn exceeds 1.81%, giant crystallized substances are formed, leading to processing defects. Therefore, in the above range, Mn and Fe are F
e+1. It is necessary to satisfy O7XMn<1°81%. As shown in FIG. 1, this range is different from the JIS regulation range and is much wider than its practical range. In addition, as a preferable range, Mn: 0.6 to 0°8%
, Fa: 0.6 to 0.95%, and Fe+1°O7
XMn<1.7%. Mg: Mg is an element effective in improving strength, and in particular, when combined with Cu, it exhibits precipitation hardening due to Al2-Cu-Mg-based precipitates during baking, and is effective in increasing the strength of the can bottom. However, if it is less than 0.5%, the effect is small, and if it exceeds 2.0%, the strength becomes too high, leading to a decrease in moldability. Therefore, the Mg amount is in the range of 0.5 to 2.0%. Si: Si is an element that causes phase transformation in the Al-Fe-Mn system crystallized product to form the so-called α phase of the AQ-Fe-Mn-Si system.The α phase has high hardness and is particularly difficult to iron. Effective in improving workability. However, if it is less than 0.1%, the effect is small, and if it exceeds 0.7%, edge cracking will occur during rolling, causing problems in manufacturing. Therefore, S
The amount of i is in the range of 0.1 to 0.7%. Cu: Cu is an element that exhibits the same effect as Mg, and Al-Cu
- It exhibits a precipitation effect due to M'g-based precipitates and is effective in improving the strength of the can bottom. However, if it is less than 0.05%, the effect will be small, and if it exceeds 0.5%, the strength will be too high, leading to a decrease in moldability. Therefore, the amount of Cu is in the range of 0.1 to 0.7%. Zn: Zn is an element that is effective in improving drawing and ironing workability and subsequent flange formability. However, if it is less than 0.05%, the effect is small;
If it exceeds 0%, there is no particular problem, but corrosion resistance tends to decrease and it is disadvantageous in terms of cost. Therefore, the amount of Zn is set in the range of 0.05 to 1.0%. However, regarding the above-mentioned Si, Cu, and Zn, it is sufficient if at least one or two or more of them are contained. Note that impurities are permissible as long as they do not impair the effects of the present invention, such as Cr (0.3%, Ti<0.2%).
, B<0.05%, and Zr<0.1%. Next, the manufacturing method of the present invention will be explained. The aluminum alloy having the above chemical components is melted and U-shaped by a conventional method, and the obtained ingot is subjected to homogenization heat treatment before hot rolling. This heat treatment is effective in improving the subsequent hot rolling properties, as well as improving formability through the formation of the α phase mentioned above and suppressing the selvage rate formed during deep drawing. However, below 500°C, both effects are small, and below 600°C,
If the temperature exceeds ℃, the performance of the plate surface will deteriorate due to burning, etc. Therefore, the homogenization heat treatment is 500-600
The holding time will vary depending on the heating temperature, but it is preferably approximately 1hr or more.For example, 550℃
If the temperature is less than □, the holding time is 1hr or more, but if the temperature is 550°C or higher, there may be no holding time. Further, this homogenization heat treatment may be performed twice. The subsequent hot rolling is rough rolling (thickness 10 mm).
Although it is divided into (above) and finish rolling, it is a continuous process. Rough rolling is carried out after homogenization heat treatment, and the starting temperature is 4
The temperature is preferably 50°C or higher. After rough rolling, the material is finished rolled into a coil, and the thickness and temperature at the end of the process are important. These influences the appropriate strength of the product board, softening due to baking after DI processing, and suppression of selvage during deep drawing. That is, if the final plate thickness is less than 1.5 mm, it is effective in suppressing the selvage rate, but the strength and softening due to baking after DI processing are insufficient. Also, 2.5+wm
If it exceeds the above, the strength will be too high, leading to a decrease in formability and an increase in selvage, leading to processing defects. Therefore, the final plate thickness is in the range of 1.5 to 2.5IIIm. In addition, the finishing temperature has a great influence especially on deep-drawn selvedges, and is 280℃.
If it is less than 28, it will cause a large increase in the ear rate, so the end temperature is 28.
Must be 0'C or higher. After that, cold rolling including intermediate annealing is performed. Intermediate annealing is an important process for increasing the strength of the product plate (corresponding to the can bottom), and is a heat treatment aimed at sufficiently dissolving Mg and Cu, which are precipitation hardened during baking during the can manufacturing process. . A cooling rate of less than 100° C./min is not preferable because precipitation occurs during cooling and the amount of solid solution decreases. Also, since heating and cooling are performed in the same line, the faster the line speed, the better from the viewpoint of productivity. Therefore, the heating and cooling rate is set to 100° C./win or more. In addition, heating temperature is an important condition for recrystallization and solutionization of Mg and Cu, but temperatures below 400°C are insufficient for both.
If it exceeds 60e-'C, it is not preferable because it causes a burning problem. Furthermore, the holding time varies depending on the temperature.
At high temperatures (for example, 500°C or higher), it is sufficient without holding, but at low temperatures (for example, 400°C), approximately 1O+in is required. Therefore, the ultimate temperature is set in the range of 400 to 600°C, and maintained within approximately 10 m1n. In addition, in terms of production, the preferred temperature range is 450 to 550°C. Needless to say, it is preferable to use a continuous annealing furnace (GAL) for intermediate annealing. Furthermore, cold rolling, which is the final step performed after intermediate annealing, is effective in improving the strength of the product sheet and softening it by baking after DI processing. However, if the cold rolling rate is less than 80%, the effect is small, so the cold rolling rate must be 80% or more. After cold rolling, if necessary, finish annealing (100 to 200'C x 1 hr or more) is performed to improve can bottom formability.
may be applied. (Example) Next, an example of the present invention will be shown 6.
% and Zn: In a composition containing 0.10%, Mn and F
About aluminum alloys with different ei. The formation status of giant crystals (primary crystals) at 654°C was observed. As a result, as shown in Fig. 2, the Al-Mn-Fe system giant crystal has Fe+1.07XM and n value of 1.8.
It can be seen that if it is less than 1, no generation occurs, and the occurrence of processing defects can be prevented. An aluminum alloy having the chemical composition shown in Table 2 was subjected to homogenization heat treatment at 580°C for 4 hours, and then hot rolled (finishing temperature 300°C) to obtain a hot rolled plate with a thickness of 2°0011111. . After that, intermediate annealing is carried out at a heating and cooling rate of 300°C/min to reach a temperature of 5oO° (:X10S
This was followed by cold rolling to a thickness of 0.30 mm. The resulting product was tested for rolling strength and baking (
After examining the strength (200° C. These material properties are shown in Table 3. In addition, to measure the selvage ratio and investigate the Erichsen value (Er value) and limit drawing ratio (LDR), an Erichsen testing machine was used. The Er value was determined by Erichsen test A method. In addition, for LDR, a 33φ punch was used and the blank diameter was varied to find the limit that could be drawn. The following formula is a formula for calculating LDR. LDR = ((Blank diameter) = (Punch diameter)) ÷ (Punch diameter) The softening amount and neck forming success rate before and after baking were determined. Here, the equipment for making cans is 45Ton drawing process.
Crank press (blank diameter 140φ, punch diameter 87φ
), then 3 on the actual DI machine (capacity 10Ton)
It was made into a 50cc DI can (66mmφX125mm)+). In addition, the limit ironing rate (L I R) is calculated by changing the inner diameter of the ironing die and calculating the amount of change in wall thickness before and after passing through the ironing die ((tl-t.) ÷ toxlOO%. Here, the wall thickness before the second pass , wall thickness after passing Sh2). Furthermore, the amount of softening before and after baking is 055 in the circumferential direction from the top of the can.
No. 1 test pieces were taken and evaluated based on the difference in tensile strength. In addition, the success rate of neck forming was determined as the ratio at which three-stage neck forming could be performed using a 45 ton crank press. The following considerations can be made from Table 3. Due to the appropriate strength and crystallized material distribution, the materials of the present invention, Nα2 to Nn4, have overall superior formability compared to the conventional high-strength materials No. The success rate is high. On the other hand, among the comparative examples Na 5 to NQ 9, NQ 5 and N
o 6 has a large softening amount at the neck part, but contains Fe and Mn amounts that form giant products (NQ5 has Fe+1.
07XMn=2.16%, Na6 is Fe+ 1.07
XMn=2.03%), a decrease in LDR and LII was observed, and some pinholes were observed in the DI can. Also, No. 8 and Nu 9 are Cu and M
In addition to a decrease in formability due to the increase in gm, a decrease in neck success rate was observed due to insufficient softening of the neck portion. 111 An ingot of an aluminum alloy having a chemical composition of Nα3 (C range of the present invention) in Example 2 was subjected to hot rolling, intermediate annealing, and cold rolling under the manufacturing conditions shown in Table 4.
The material properties were investigated using the same evaluation procedure as in the case of , and the results shown in Table 5 were obtained. The following considerations can be made from Table 5. The A and B process materials, which are the materials of the present invention, have high strength (yield strength after baking), low edge ratio, and high formability. The high strength means that the pressure resistance is low, which means that it is advantageous for thinning. On the other hand, since the homogenization heat treatment temperature of C process material is low,
High ear rate and low LIR. The D process material also exhibits the same behavior as the C process material because the hot rolled plate thickness is thick. In addition, the E-process material has a low end temperature of hot rolling, leading to a high selvage rate. Further, the materials processed in steps F to (1) have low yield strength after baking due to insufficient solid solution of Cu and Mg or insufficient amount of cold rolling, and are unsuitable for thinning of the material. In particular, the process material (2) is an example in which conventional batch annealing was used, and the yield strength after baking is low. This occurs because the heat treatment conditions among the manufacturing conditions are not appropriate even for the AI2 alloy having chemical components within the range of the present invention.

[Left below]

(Effects of the Invention) As detailed above, according to the present invention, by appropriately regulating the amounts of Mn and Fe among chemical components, the strength of the can bottom can be increased and the amount of softening of the neck can be increased. Therefore, neck formability is improved, and the entire can body can be made thinner.

[Brief explanation of drawings]

Figure 1 shows the JIS established range, its practical range, and the scope of the present invention for Mn and Fe contents, and Figure 2 shows the Al-Mn
FIG. 3 is a diagram showing the relationship between Mn and Fe amounts on the generation of large -Fe-based products. Patent applicant Hisashi Nakamura, Patent attorney representing Kobe Steel, Ltd. Figure 1 MTl (%)

Claims (2)

[Claims] (1) In weight% (the same applies hereinafter), Mn: 0.5 to 1.0
%, Fe: 0.5-1.2% and Mg: 0.5-2.0
%, Mn and Fe are Fe+1.07×Mn<1.81%
Si: 0.1 to 0.
．． 7%, Cu: 0.05-0.5% and Zn: 0.05
An aluminum alloy hard plate with excellent formability, characterized in that it contains one or more of the following: ~1.0%, with the remainder consisting of Al and unavoidable impurities. (2) Mn: 0.5-1.0%, Fe: 0.5-1.2
% and Mg: 0.5 to 2.0%, Mn and Fe are Fe +
Contains so as to satisfy the relationship of 1.07×Mn<1.81%, and further contains Si: 0.1 to 0.7%, Cu: 0.05 to
0.5% and Zn: 0.05 to 1.0%, and the remainder is Al and inevitable impurities. After heat treatment, hot rolling is completed to a plate thickness of 1.5 to 2.5 m.
m, performed at a finishing temperature of 280°C or higher, and then intermediate annealing at a heating and cooling rate of 100°C/min or higher and a final temperature of 400°C or higher.
A method for producing an aluminum alloy hard plate with excellent formability, characterized by performing final cold rolling at a temperature of 600°C and a rolling reduction of 80% or more.