KR100569454B1 - Method of manufacturing al-mg-si alloy sheet - Google Patents

Abstract

The present invention relates to a method for manufacturing an aluminum-magnesium-silicon alloy sheet in which the leasing is suppressed, wherein at least one selected rolling pass including at least one selected rolling pass including the last rolling pass among the rolling passes during cold rolling is used. Cold rolling is performed in an idle state to concentrate the shear deformation of the plate to control the assembly structure, thereby manufacturing an aluminum-magnesium-silicon alloy plate that can significantly reduce the leaching phenomenon, which is a surface defect of the plate. It is about.

According to the manufacturing method of the present invention, by the idle roll during cold rolling, shear deformation is additionally added to the plate to improve the texture by removing the goose texture that causes leasing. It is possible to obtain an effect of remarkably improving, and in the end, the surface polishing process of the final molded product may be omitted, thereby reducing the product cost and reducing the defective rate.

Aluminum-magnesium-silicon alloy sheet, ridging, texture, goth bearing, RW bearing, cold rolling, work roll, idle, shear deformation, lowering

Description

Method for manufacturing aluminum-magnesium-silicon alloy sheet material in which leasing is suppressed {Method of manufacturing Al-Mg-Si alloy sheet}             

1 is a schematic view showing the operating state of the work roll in the manufacturing method according to the present invention,

Figure 2a and Figure 2b is a result of the finite element analysis showing the shear strain imposed on the plate by the present invention and the conventional manufacturing method, respectively,

Figure 3a is a surface photograph showing the deformation result after 20% tension of the specimen prepared by the manufacturing method according to the present invention,

Figure 3b is a surface photograph showing the deformation result after 20% tension of the specimen prepared by a conventional manufacturing method.

<Explanation of symbols for the main parts of the drawings>

1: Alloy Plate 2a: Upper Work Roll

2b: lower work roll

The present invention relates to a method of suppressing the ridding of the surface defects of an aluminum-magnesium-silicon alloy sheet, and more particularly, at least one of the upper and the selected rolling passes including a final rolling pass during cold rolling during the manufacture of the sheet. Cold rolling with one of the lower work rolls in an idle state, thereby actively inhibiting the development of the goose texture that causes leaching by applying shear deformation to the plate, thereby increasing the leachability. .

Recently, in the automobile related industry, research is being actively conducted to apply an aluminum alloy plate as a material of a car body instead of the existing steel plate for the purpose of improving fuel efficiency and reducing the weight of the vehicle body.

It is well known that aluminum has a specific gravity less than 1/3 compared to steel, and thus, when used, it is possible to reduce the weight of the vehicle body and thus greatly improve fuel efficiency.

However, lightweight materials, such as aluminum plates, have a fundamental limitation that the strain for forming is less than one third of steel.

In addition, since wrinkles are severe during molding and there is a limit in that the surface quality of the final molded sheet is degraded due to bending (rising phenomenon), it is true that there are many difficulties in expanding and applying aluminum as a body material.

In some cases, it is possible to apply the 5000-based aluminum-silicon alloy sheet having good moldability, but this is a problem of insufficient rigidity and difficult to control the surface quality after molding. Recently, the 6000-based aluminum-silicon-alloy sheet is applied. The trend is even greater.

Since the 6000 series aluminum-magnesium-silicon alloy sheet has a small hardening ability compared to the 5000 series aluminum-magnesium alloy sheet, the yield strength after paint coating is increased, thereby improving dent resistance and increasing rigidity. Suitable for use in automotive panels.

However, the aluminum-magnesium-silicon alloy sheet material has a disadvantage in that surface bending, called a ridging phenomenon, occurs during secondary processing such as press working.

This leaching phenomenon is a defect in which uneven curvature such as streaks on the surface of the plate after the secondary processing is long along the direction parallel to the rolling direction, and occurs when additional deformation such as tension is applied to the rolled plate.

In other words, if the grains stretched in the rolling direction are further deformed, bending occurs at different heights on the surface of the plate, resulting in long ridges and valleys parallel to the rolling direction. .

When this leaching phenomenon occurs, surface bending becomes more pronounced after coating, which causes the quality of the surface of the plate to be degraded, which requires additional processes such as surface polishing, and causes problems such as increase in manufacturing cost and delay in delivery. do.

Therefore, it is necessary to suppress the leaching phenomenon by adjusting the process variables in the production and production of alloy plate material, and until now there is almost no research on the leaching phenomenon after secondary molding such as press working.

Leasing in aluminum-magnesium-silicon alloy plates occurs as a result of poor control of the texture in the plate, especially when the Goss orientation develops.

After annealing, the aluminum-magnesium-silicon alloy sheet has a {011} <100> goth orientation, which is a cubic crystal structure, but the average firing ratio of this bearing is 1 or less, which is considerably lower than that of a general steel sheet. Producing to maintain elongation without developing tissue is the main goal of producing highly formed aluminum-magnesium-silicon alloy sheets.

In order to increase the formability, the addition of alloying elements, such as magnesium and silicon, to aluminum can achieve the desired purpose, but the {110} <001> goose direction, which causes leasing, develops, which leads to the addition of alloying elements. Leasing occurs more severely than untreated aluminum plates.

Goose bearing is the main cause of surface bending because the thickness reduction is maximized at 90 degrees with respect to the rolling direction, unlike other orientations.

In order to overcome the occurrence of the leaching phenomenon by the development of the goose defense texture, the leaching phenomenon can be suppressed and controlled by controlling the addition ratio of the alloying elements as proposed in US Pat. No. 6,231,809.

However, it is possible to change the distribution of goth bearing due to the change of alloy composition, but it is difficult to reduce the goth bearing volume fraction due to the change of operating variables such as rolling step and annealing condition, and in this case the bearing Since the development may be more advanced than the process, the leaching phenomenon may be intensified. Therefore, there is a limit to suppressing the leaching phenomenon by the current passive texture control.

Accordingly, the present invention has been invented to solve the above problems, maintaining one of the work rolls in the idle state in at least one selected rolling pass including the last rolling pass of the rolling pass during cold rolling of 6000 series aluminum alloy sheet It is aimed to suppress the development of goth bearing which is the main cause of leasing by changing the texture of alloy plate by cold rolling.

This purpose is to allow one of the two upper and lower work rolls to be operated in the idle state when cold rolling the 6000 series aluminum alloy sheet so that the idle rolls prevent the rolling of the sheet (the opposite shear deformation). To this end, as a whole plate can be achieved by the present invention that the cold rolling is applied to the shear deformation in the rolling direction and the shear deformation in the opposite direction of the rolling.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The present invention is a method for producing an aluminum-magnesium-silicon alloy sheet material,

At least one selected rolling pass, including the last rolling pass, to maximize the shear deformation of the alloy sheet passing between the upper and lower work rolls when hot-rolling an aluminum-magnesium-silicon alloy slab Cold rolling is performed by keeping one of the work crawl and the lower work roll in an idle state.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The present invention relates to a method for producing an aluminum-magnesium-silicon alloy sheet in which the occurrence of leaching is suppressed, wherein two work rolls of upper and lower portions in at least one selected rolling pass including the last rolling pass among the rolling passes during cold rolling of the alloy sheet By performing cold rolling with one of the idle state, the shear deformation of the plate is concentrated to control the assembly structure, thereby reducing the leasing phenomenon, which is a surface defect of the aluminum-magnesium-silicon alloy sheet, significantly. The present invention relates to a method for producing a magnesium-silicon alloy sheet material.

That is, the present invention is a method for producing a 6000-based aluminum alloy sheet containing 0.1 to 1.5% magnesium and 0.3 to 1.6% silicon by weight, after hot rolling the 6000-based aluminum alloy slab formed as described above When cold rolling, the primary focus is on cold rolling by driving one of the upper and lower work rolls in an idle state in at least one selected rolling pass.

In the present invention, in order to suppress the leaching phenomenon of the 6000 series aluminum alloy sheet material, the goth texture developed in advance is developed at a volume fraction of 1% or less, and instead, { The volume fraction of the 001} <110> orientation is developed to more than 15%.

In general, the 6000-based aluminum alloy sheet has a strong development of {112} <111> texture, known as copper-like texture, during cold rolling regardless of the amount of components, and additionally, goth bearing and other orientations are developed.

These bearings are recrystallized during the annealing process following the cold rolling, so that the copper orientation becomes cubic orientation and the goth orientation develops into a goth orientation. When these goth and cubic textures are developed, low average plastic deformation ratio and rolling Due to the occurrence of ear at 0 degrees and 45 degrees with respect to the direction, not only the primary problem that the moldability is significantly lower than that of the existing steel sheet, but also the leasing phenomenon develops and degrades the surface quality.

However, since the development of cubic bearings cannot be prevented unless special cold rolling is applied, it is desirable to eliminate the difference in deformation thickness between cubic bearings and goth bearings, which are the main causes of leasing.

Therefore, in order to suppress the leasing phenomenon, the cold rolling conditions must be carefully managed so that the goth defense is not developed, because the goth bearing is developed not in the annealing process but in the cold rolling process.

It is not easy to control the goth bearing, but during the cold rolling, the cubic texture is developed and the cubic crystal texture is developed during the annealing process, and the goth defense is additionally developed when the copper texture is developed. Done.

This is because the rotation of the grain passes through the goose direction, the brass direction ({110} <112>), and the S direction ({123} <634>) to the copper direction.

Therefore, in order to suppress the goose azimuth during rolling, it is preferable to avoid rolling in the plane strain condition in which copper type aggregate structure develops.

As a result, in order to suppress the goose direction, it is necessary to suppress the development of the copper direction which is generally developed during cold rolling, which is impossible in the plane deformation condition, which is cold rolling condition as described above, and can be achieved through shear deformation. Can be.

The present inventors found that the application of shear deformation results in the development of shear aggregates in which the {001} <110> RW orientation is the main orientation, rather than the development of copper-like aggregates, and also suppresses the development of goth orientation. .

In other words, after the development of the goose direction by imposing the shear deformation in the cold rolling stage, the grains to be rotated to the copper direction are rotated to the {001} <110> RW direction to suppress the development of the goth direction, followed by an annealing process and other post-processes. When manufacturing a 6000 series aluminum alloy sheet, it is possible to suppress the leaching phenomenon, which is a problem of the existing alloy sheet.

Accordingly, the present invention is to improve the existing cold rolling process to significantly suppress the leaching phenomenon, in particular one of the upper and lower work rolls in at least one selected rolling pass including the last rolling pass of the rolling pass of cold rolling It is characterized by cold rolling while being kept in a state, that is, without power.

As is well known, conventional cold rolling is intended to be rolled over several passes (typically five passes for 6000 aluminum alloy plates), and a pair of alloy plates are provided for each rolling pass. It is intended to be rolled while passing between the upper and lower work rolls.

Here, the work roll is a roll that directly presses the plate, that is, a roll that transmits force directly to the plate, the force that each work roll presses the plate is provided by each press roll, the pressing force of the press roll through the intermediate roll It is transmitted to each work roll.

In normal cold rolling, both the upper and lower work rolls are rotated in opposite directions by external driving means such as a motor to press the alloy sheet and push it out in the passing direction.

In the present invention, when cold rolling the 6000-based aluminum alloy sheet in order to improve the lowering property of the alloy sheet in the cold rolling, one of the two work rolls of the upper and lower parts is put into an idle state, thereby The work roll serves to hinder the rolling of the plate (opposite shear deformation), so that the cold rolling is applied to the entire sheet as the shear deformation in the rolling direction and the shear deformation in the opposite direction to the rolling.

Here, the idle work roll, that is, the idle roll is rotated in the idle state by the force of the plate passing through, as shown in Figure 1, that is friction with the plate, without connecting the power of the external drive means, wherein the idle The roll rotates in the opposite direction to the opposite work roll to simply hold the plate.

In FIG. 1, reference numeral 2a denotes an upper work roll rotating by an external drive means, and reference numeral 2b denotes a lower work roll (idle roll) rotated by a plate in an idle state, and reference numeral 1 denotes an alloy plate. Indicates.

In the present invention, the idle roll is applied to at least one or more selected rolling passes including the last rolling pass of the whole rolling pass of the cold rolling, and of course, when one work roll is operated in the idle state in the rolling pass to which the idle roll is applied, this combination Naturally, the opposite work roll should be driven by external driving means such as a motor.

2A and 2B are diagrams showing the results of finite element analysis showing shear deformations imposed on a plate by the present invention and the conventional manufacturing method, respectively, when one work roll is idled and idled during cold rolling. A comparison of the results when no rolls are applied is shown.

In the conventional cold rolling, it is not easy to apply shear deformation to the alloy sheet, and even if applied, it is not possible to control the desired texture by concentrating on the surface. However, the present invention suggests that shear deformation is applied to the entire surface of the sheet. There is an advantage that can almost completely prevent the development of goth defense causing leasing.

FIG. 2a shows that when one work roll is rotated in an idle state, the cold rolling is applied to the entire shearing material in the rolling direction and the shearing deformation in the opposite direction of rolling.

That is, in the present invention, the plate is subjected to shear deformation in the rolling direction by the work roll to which power is transmitted, and the work roll in the idle state is subjected to shear in the opposite direction to the rolling direction. As a result, the plate is subjected to more than two times the shear deformation of the conventional method cold rolling.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Examples 1 to 2 and Comparative Examples 1 to 3

The following example shows the present invention in which a shear deformation is added while the lower work roll is in an idle state during cold rolling in the manufacture of a 6000 series aluminum alloy sheet, and the comparative example embodies a conventional method in which no idle roll is applied. will be.

First, aluminum-0.55 wt% magnesium-1.2 wt% silicon alloy was cast to a thickness of 150 mm using a general DC casting method, and then homogenized at 480 ° C. for 48 hours, and hot rolled to 10 mm.

The hot rolling start temperature was 450 ° C, and the final winding temperature was 310 ° C.

Thereafter, cold rolling was performed, but using a general irreversible rolling mill at a rolling reduction rate of 88%, and the annealing process followed the T4 condition.

Thereafter, the quality characteristics evaluation specimens were prepared, and then the degree of leasing was measured by 20% tensile test, and the results are shown in Table 1 together with the texture volume fractions.

Cold rolling typically works over five passes, but since there are five cases in which the lower work roll can be idled, a total of 16 combinations are possible. As an example, the case where the idle roll was applied in the fifth pass (final pass) (Example 1) and the case where the idle roll was applied in the fourth pass and the fifth pass (Example 2) are shown.

As a result of the comparative example, whether or not ridging occurs of a 6000 series aluminum alloy sheet produced by a conventional cold rolling method is shown together with the volume fraction of the texture.

As can be seen from Table 1, leasing did not occur in the 6000-based aluminum alloy sheet (Examples 1 and 2) manufactured by the present invention, but in the alloy sheet manufactured according to the manufacturing method of the present invention, Shear deformation causes {001} <110> RW orientation to develop among the components of the tissue, and this orientation remains after cold rolling and annealing, thereby suppressing the development of goth orientation. You lose.

In addition, in Comparative Examples 1 to 3 produced by the existing method, the ridging height is increased due to the development of goth bearing.

In addition, Figure 3a is a surface photograph (Example 1) showing the deformation result after 20% tension of the specimen prepared by the manufacturing method according to the present invention, Figure 3b is 20% tensile of the specimen prepared by the conventional manufacturing method The surface photograph (Comparative Example 1) showing the post deformation result.

Referring to Figures 3a and 3b, it can be seen that the leasing phenomenon occurs relatively large in the specimen prepared according to the conventional manufacturing method (in Figure 3b the vertical streaks of the surface of the specimen is apparent compared to Figure 3a).

In particular, when looking at the surface immediately after tension, as shown in the two photographs, the difference between the specimens according to the presence or absence of leasing was not clearly revealed, but the vertical stripes, that is, leasing in FIG. It becomes a defect.

As described above, according to the method for manufacturing an aluminum-magnesium-silicon alloy sheet according to the present invention, one of two work rolls is idled in at least one selected rolling pass including the last rolling pass during cold rolling of the alloy sheet. By maintaining the additional shear deformation by holding, the effect of suppressing the growth of the goose bearing that causes leasing can be remarkably improved, and furthermore, the polishing of the surface of the final molded product can be omitted. The effects of savings and reduced defect rates can be expected.

Claims (1)

In the method for producing an aluminum-magnesium-silicon alloy sheet material, At least one selected rolling pass, including the last rolling pass, to maximize the shear deformation of the alloy sheet passing between the upper and lower work rolls when hot-rolling an aluminum-magnesium-silicon alloy slab A method for producing an aluminum-magnesium-silicon alloy sheet material, in which leasing is suppressed, wherein one of the work roll and the lower work roll is held in an idle state to perform cold rolling.

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