JPS5918466B2 - Manufacturing method of Al alloy plate for packaging - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an alloy plate A for packaging, and in particular, to improve the strength and formability necessary for the body material of beer and soft drink cans (hereinafter referred to as canvas body material). A [alloy plate,
This invention relates to a manufacturing method with high productivity.

Characteristics required for No. 1 alloy sheet for packaging such as canvas material are: (1) good deep drawability, (2) small deep drawing selvage (small crystallographic anisotropy) , (3) Good ironing workability, (4) Good stretching workability, (5) Good necking and flanging properties, and (6) Sufficient strength. (7) It has good corrosion resistance. (8) It has a beautiful appearance after iron making.

AA3004 is the most commonly used canvas material.

This is an A[alloy that has Mn and Mg as essential components and other elements are regulated as impurities, but if this is used as a canvas material, seizure is likely to occur during ironing.

In other words, the ironing process is performed once after the re-drawing of the iron making process, and the side wall of the re-drawn can body is thinned by ironing dies; the inner volume is secured by stretching the can in the height direction; At this time, the friction between the can wall and the ironing die is extremely large.

Therefore, seizure is likely to occur during this process, and when this occurs, frictional resistance increases, eventually leading to breakage.

Furthermore, even if the die does not break, the appearance is significantly impaired or the life of the die is significantly shortened.

Therefore, in order to prevent seizure, it is necessary to add lubricity to the machining surface, and water-soluble lubricating oil is usually used to cool the machining heat.

However, since seizure cannot be completely prevented by using lubricating oil alone, it is desirable that the material itself has good lubricity (or seizure resistance).

On the other hand, in order to improve the formability of alloy 1 for packaging, in the conventional manufacturing process, the hot rolled plate must be subjected to at least one intermediate annealing or precipitation treatment after hot rolling or during cold rolling. , it is said that satisfactory characteristics cannot be obtained.

However, a considerable amount of equipment and energy is required to perform intermediate annealing, and productivity also decreases due to the increase in the number of steps, so if the intermediate annealing step can be omitted,
It is considered to be extremely advantageous in terms of equipment, operating costs, productivity, etc.

Under the above-mentioned circumstances, the present inventors have developed an A7 alloy sheet for packaging that improves the seizure resistance of the alloy itself and provides excellent formability without intermediate annealing. In order to establish this method, various studies have been conducted on the types and amounts of added alloying elements, soaking treatment conditions, hot rolling conditions, etc.

As a result, we found that the above objective can be achieved by specifying the manufacturing conditions as shown below, and have finally completed the present invention.

That is, the present invention 1 is the method for manufacturing the packaging A [alloy plate]
Fe as an essential component: 0.3 to 0.7% (same as 2% by weight or less) M
In addition to containing n: 0.5-2% Mg: 0.5-2% Si: 0.05-0.4%, Cu: 0.01-0.5% Cr: 0.01-0.5 % or more selected from Ti: 0. O 1 to 0.3% B: O, OO 1 to 0.05% A containing one or more selected from O, OO 1 to 0.05%, the remainder being substantially Al
After being subjected to soaking treatment at a high temperature above 24 hours, hot rolling was carried out so that a final plate thickness of 1.8 to 6 rILm was obtained at a finishing temperature of 320°C or above, and then 50°C without intermediate annealing. The gist lies in performing cold rolling of % or more.

The structure and effects of the present invention will be explained below, along with the reasons for determining the types of added alloying elements, the amounts added, and the soaking treatment conditions. All changes within this range are included within the scope of the technology of the present invention.

First, the added alloying elements will be explained.

Together with Mn, Fe forms AlMn-Fe crystals and precipitates, and is an essential element for preventing seizure during ironing, improving formability, and improving the appearance of products.

That is, according to the results confirmed by the inventors through experiments, Al
It has been found that seizure resistance can be significantly improved by forming relatively large-sized Al-Mn-Fe precipitates in the matrix of the base alloy.

When a water-soluble lubricant is used in a normal iron-making process, the concentration of the lubricant fluctuates constantly due to water evaporation, etc., and deteriorates over time.

Moreover, the temperature of the lubricating oil fluctuates due to fluctuations in machining heat and ambient temperature, and the viscosity of the lubricating oil also changes constantly, so the lubricating performance changes significantly over time, and seizure cannot be completely prevented using the lubricant alone.

However, as mentioned above, if A[-M n-Fe system crystals and precipitates are formed in the A1 alloy, the seizure resistance of the alloy itself will improve, and the above-mentioned changes in the properties of the lubricant will occur. Despite this, seizure can be effectively prevented.

In order to exhibit these effects significantly, at least 0.3% or more of Fe must be added.

However, when the content exceeds 0.7%, the seizure resistance improvement effect reaches a saturated state, and instead a large amount of A7-Mn-Fe-based giant primary crystal compounds are generated, resulting in decreased formability or during deep drawing. 4
Bad effects such as the ear in the 5-degree direction becoming larger become significant.

Mn is an essential element to ensure the strength required for the AA gold alloy for packaging, as well as to generate the Al Mn-Fe type precipitates in an appropriate size and amount to improve seizure resistance. To ensure these effects, 1 is at least 0.
．． It is necessary to add 5% or more.

However, if it is too large, as in the case of Fe, the amount of giant primary crystal compounds produced increases and the formability is inhibited, so it must be kept at 2% or less.

Mg, together with Mn, is an indispensable element for obtaining a certain strength, and must be added in an amount of at least 0.5%.

However, if the amount is too high, the strength becomes too high, resulting in poor formability such as deep drawing and overhang, as well as seizure resistance during ironing, and furthermore, the solid solubility of alloying elements decreases, resulting in the formation of giant primary crystal compounds. Since it becomes easier to generate, it should be kept at 1% below 2%.

Si has the effect of suppressing deep drawing selvages during ironing and subsequent removal of a can from a punch.

In other words, to satisfy the required strength of one piece of canvas material)
This requires cold rolling of about 50% or more after hot rolling, but this tends to cause selvages in the 45 degree direction during deep drawing.

This tendency is particularly strong in the alloy of the present invention in which 1 piece of Fe is added to prevent seizure.

However, these defects can be suppressed by adding 0.05% or more of Si.

However, if it is too large, the moldability will deteriorate slightly, so it is best to limit it to 0.4% or less.

Both Cr and Cu are equivalent substances in that they exhibit the same strength-improving effect as Mn, and Cu is particularly preferred because it has the advantage of not easily deteriorating formability due to the formation of giant primary crystal compounds.

This strength improvement effect is achieved by adding 0.01% Cr and/or Cu.
It is effectively exhibited by adding the above.

However, when the Cr content exceeds 0.4%, A I -M n
Formability is inhibited by the formation of -Cr-based giant primary crystal compounds, and if the amount of Cu exceeds 0.5%, corrosion resistance decreases, making it unsuitable as a packaging material.

Ti and B can be added individually or simultaneously in the form of TiB2, etc., and have the effect of uniformly and finely scraping the internal structure during casting.

In order to exhibit these effects significantly, Ti should be 0.01
% or more, B should be added in an amount of o, oot% or more.

At 0.3% Ti or 0.05% B, the above effects reach a saturation level of 1, and adding more than this is not only uneconomical, but also tends to generate giant primary crystal compounds. This is not preferable because the moldability deteriorates.

In addition, normal impurity elements such as Zn contained in normal A and A1 alloys do not have any particular adverse effect as long as they are contained within the normal range.

Although the Al-based alloy of the present invention must satisfy the above requirements, the object of the present invention cannot be achieved unless the soaking conditions and hot rolling conditions described below are further complied with.

That is, A [When soaking the base alloy ingot, the temperature is 55
The conditions must be 0°C or higher and within 24 hours.

The reason for this is as shown below.

That is, the present invention has a major feature in that a predetermined amount of Fe is added as explained above; this improves seizure resistance. In order to produce a large amount, the soaking temperature must be set to 550°C or higher.

In addition, as will be detailed later, the hot rolling end temperature is set at 320°C or higher, and recrystallization is performed at the end of hot rolling (until it is cooled to a temperature range that allows cold rolling), eliminating the need for intermediate annealing. An important feature of the present invention is that a good structure can be obtained in both cases, but by setting the soaking temperature to a high temperature of 550°C or higher1, the hot rolling end temperature is 320°C.
It was easy to satisfy the above conditions.

Moreover, if the soaking temperature is too low, fine precipitates are generated during the soaking process, suppressing recrystallization, and obstructing the purpose of the present invention of recrystallizing at the end of hot rolling.

In addition, the soaking time may be set appropriately depending on the size of the ingot, and if the ingot is large in thickness, length, and width, it may take a long time (by rubbing).

However, even the largest ingot currently available can be sufficiently homogenized by soaking for 24 hours.

Moreover, in this step, the growth of the AA'-Mn-Fe-based precipitates progresses and the seizure resistance is improved, but even if soaking is continued for more than 24 hours, the growth of the precipitates hardly progresses. Heat energy is wasted and productivity is reduced.

After soaking under the above conditions, hot rolling is immediately carried out once, but the condition is that the finished plate thickness is at least 1
．． It must be 8 to 6 m'llL and the finishing temperature must be 320°C or higher.

In the conventional manufacturing method of A1 alloy sheet, the hot-rolled A alloy sheet is subjected to intermediate annealing immediately after or after cold rolling as necessary, and the mechanical properties, grain size and The properties described above were obtained by adjusting the texture, but in the present invention, by specifying each condition from soaking to hot rolling as described above, it has become possible to omit intermediate annealing. .

A more detailed explanation will be given of recrystallization at the end of hot rolling, which is an important feature of the present invention.

A1 with less elements that cause internal strain (Mn, Mg, etc.)
In the case of alloys or pure Al, hot rolling must be carried out at a very high temperature in order to complete recrystallization at the end of hot rolling.

However, since the temperature decreases as the final plate thickness decreases, it is difficult to obtain a thin hot rolled plate having a good recrystallized structure.

That is, in order to carry out effective recrystallization at the end of hot rolling, it is thought that driving strain to cause recrystallization and thermal energy to release the strain are essential.

In this regard, in the present invention, a predetermined amount of Mg and Mn is contained in the A1 alloy component to increase internal strain during hot rolling, so this becomes a driving strain and recrystallization can be performed with relatively little thermal energy. can be done.

That is, sufficient recrystallization is possible at the hot rolling stage without special intermediate annealing.

However, even in this case, a minimum amount of thermal energy is required, and from this point of view, the hot rolling end temperature was set at 320° C. or higher.

In addition, when the finished plate thickness is 1, the thicker the plate, the easier it is to maintain the finished temperature at a high and constant level, but the internal strain caused by rolling becomes smaller, the drive die becomes smaller, and recrystallization is completed in the hot rolling stage. things become difficult.

Moreover, when this is cold rolled to a thickness suitable for ordinary canvas body materials, the strength becomes extremely high due to work hardening (work hardening), and the formability of the final product sheet decreases.

Therefore, in order to prevent these defects from appearing, the plate thickness at the end of hot rolling was set to 6 or less.

On the other hand, if the final plate thickness is less than 8 mm, it becomes difficult to raise the final temperature to 320°C or higher.

In particular, when using a material with a high melting point such as pure 1' as the hot-rolled material, the soaking temperature can be increased, so the start and end temperatures of the subsequent hot rolling can also be increased. Since the melting point of alloys containing a considerable amount of alloying elements such as Mn, Mg, and Fe (such as the alloy used in the invention) is low, the soaking temperature must be kept relatively low, and the start and end of hot rolling must be kept at a relatively low temperature. The temperature will also drop.

Therefore, if the plate thickness at the end of hot rolling is reduced, the temperature at the end of rolling can be reduced by 3.
It becomes difficult to maintain the temperature at 20° C. or higher, and it becomes difficult to obtain a completely recrystallized hot rolled sheet.

Therefore, in the present invention, the finished plate thickness is limited to 1.8 r/ or more in order to ensure an appropriate rolling finish temperature.

By adopting the above soaking and hot rolling conditions,
A rolled sheet having a sufficient recrystallized structure is obtained at the end of hot rolling, and then cold rolling is performed by 50% or more.1 Thereby, an A1 alloy sheet having the strength required as a canvas body material is obtained.

After this final cold rolling, if necessary, stabilization annealing (at about 100 to 150° C. for less than 1 hour) can be performed to adjust the mechanical properties.

In this way, in the present invention, intermediate annealing after hot rolling can be omitted, which has an important meaning in improving seizure resistance and obtaining a beautiful product.

That is, when intermediate annealing is performed after hot rolling, Mg diffuses into the surface of the plate material and is further oxidized to become MgO.
-Mn The Fe-based precipitates reduce the anti-seizure property that has been so painstakingly imparted, and furthermore, the surface of the plate material takes on a black tinge, deteriorating its aesthetic appearance.

However, in the present invention, there is no need to perform intermediate annealing, so there is no risk of causing the above-mentioned problems.

The present invention is roughly constructed as described above, and its effects can be summarized as follows.

■ Including Mn and Fe as alloying elements and specifying the soaking conditions1.Thus, Al-Mn-Fe system crystals and precipitates are formed in the Al matrix, and one alloy plate is formed. Since it has self-lubricating properties, it is possible to prevent seizure as much as possible, especially during ironing.

Therefore, discoloration during processing is suppressed and beautiful products can be obtained.
Furthermore, die wear is also significantly suppressed.

(2) Intermediate annealing can be omitted], so the seizing resistance improvement effect described in (2) above can be maintained as is.

Furthermore, no equipment or thermal energy is required for intermediate annealing.
This also improves productivity by reducing the number of steps.

■ The resulting product has excellent strength and also exhibits excellent moldability.

Therefore, it can be used in a wide variety of packaging materials, including canvas materials for beer and soft drinks.

Next, examples of the present invention will be shown.

Example l A [alloy ingot (thickness: 500
mm) was soaked at 590°C for 6 hours, then hot rolled at a final thickness of 2.5 am and a final temperature of 330°C, and then
．． The mechanical properties of the A1 alloy obtained by cold rolling to a thickness of 4 arn and the seizure resistance during ironing were investigated.

The results are shown in Tables 2 and 3.

However, in the seizure resistance test, the surface of each alloy plate was degreased before being subjected to the test.

○: Seizure (no) ■: Seizure (small) △: Seize (medium) Almost no difference is recognized.

However, the seizure resistance is significantly affected by the amount of Fe;
If it is less than 3% (alloy A), it is extremely poor, whereas alloys that satisfy the Fe content specified in the present invention (alloys B and C)
The seizure resistance is extremely good.

Also, using alloys N and B shown in Table 1, soaking conditions were set to 5.
Same as above except that the temperature was changed to 40°C x 4 hours.
An alloy plate with a thickness of 4 am was manufactured and subjected to a seizure resistance test.

The results are shown in Table 4. However, the results under soaking conditions of 590° C. x 6 hours are also shown.

(○, @, △, ×: Same as above) As is clear from the results in Table 4, even if the Fe content satisfies the requirements of the present invention, the seizure resistance is poor when the soaking temperature is lower than 550°C. The improvement effect is insufficient, and even if the soaking temperature satisfies the requirements of the present invention, if the Fe amount is less than 0.3%, the seizure resistance will hardly improve.

Example 2 An AA alloy ingot having the composition shown in Table 5 (thickness: 1500 m)
m) was soaked at 590℃ for 6 hours, and the final plate thickness was reduced to 2.
．． 5 rnm constant, end temperature 330°C, 315°
C or 300° C., and then cold rolled to a thickness of 0.4 rnrrt.

The mechanical properties of the obtained rolled plate and the selvage ratio after one drawing process were measured.

However, the ear rate was measured as follows.

[Ear rate measurement conditions]

Punch diameter: 33 guns Aperture ratio 20.6 Clearance: 25% Wrinkle presser load: 100kg Aperture speed: 13rIt11L/sec The results are shown in Tables 6 and 7.

As is clear from Tables 5 to 7: When the hot rolling end temperature is set at 330°C, the selvedge ratio in the drawing process of the obtained product is almost the same for the tail, center, and head. Uniform and small, but with a finishing temperature of less than 320°C (by rubbing,
The difference in the selvage ratio in the longitudinal direction of the rolled coil is large and the absolute value is also large.

Moreover, FIG. 1 is a parallel cross-sectional micrograph of each alloy plate after hot rolling, and recrystallization is completed when the finishing temperature is less than 320°C.

Example 3 50X from a large A1 alloy ingot with the composition shown in Table 8
75X1001rL1? Small ingots of L were cut out, subjected to soaking treatment at different temperatures, cooled with water, and stored in the state immediately after soaking, and the internal structure of each ingot was observed using an optical microscope.

The results are shown in Figure 2). As is clear from Figure 2 (this,
Although crystallized substances are observed in the as-cast state, no precipitates are formed.

However, when soaking is performed, precipitates are formed, and the higher the soaking temperature, the larger the size of the precipitates.

In the case of soaking treatment at 450℃ for 4 hours, it appears that no precipitates were formed in the photograph, but as is clear from the electron micrograph in Figure 3, in reality, a large amount of very fine precipitates were formed. is being generated.

However, as explained in the main text of the specification, if the precipitates are relatively large in size, they will not improve the seizure resistance (because they will not contribute).
For this purpose, it is necessary to adopt a soaking temperature of 550°C or higher.

These crystallized substances and precipitates are non-uniformly distributed in the ingot after soaking, but become uniformly distributed by the subsequent hot rolling and cold rolling.

[Brief explanation of drawings]

Figures 1 to 3 are micrographs substituted for drawings showing the internal structure of the A1 alloy.

Claims (1)

[Claims] I Fe: 0.3 to 0.7% (same as 2% by weight or less) M
n: 0.5-2% Mg: 0.5-2% Si: 0.05-0.4% Cu: 0.01-0.5% Cr: 0.01-0 .5% and one or more selected from Ti: 0.01-0.3% B: 0.5%. An A1 alloy ingot containing one or more selected from 1 to 0.05% of OO, with the remainder consisting essentially of A, is subjected to soaking treatment (after soaking and finishing) at a high temperature of 550°C or higher for within 24 hours. Plate thickness 1.8~6rI
A method for producing an A1 alloy sheet for packaging, characterized by hot rolling one time so that LrIL is obtained at a finishing temperature of 320° C. or more, and then cold rolling by 50% or more without intermediate annealing.