JP5699255B2 - Method for producing AlMgSi aluminum strip - Google Patents

Description

  The present invention is a method for producing a strip from an AlMgSi alloy, in which a rolled ingot is cast from an AlMgSi alloy, the rolled ingot is homogenized, the rolled ingot at a rolling temperature is hot-rolled, and then optionally It relates to a method in which it is cold rolled to a final thickness and the finished strip is solution annealed and quenched. Furthermore, the invention relates to the advantageous use of the AlMgSi aluminum strip so produced.

  Aluminum alloy sheet metal not only characterized by a particularly high strength value, but also at the same time has a very good formability and allows a high degree of deformation, not only for the construction of automobiles, but also for other applications It is also needed in the field, for example in aircraft manufacturing or railway vehicle construction. Typical application fields in the construction of automobile vehicles include body members and chassis members. In the case of visible painted parts, for example car body metal sheets that can be seen from the outside, the material must be further shaped after painting so that the surface is not damaged by defects such as distortion patterns or roping. . This is particularly important when using aluminum alloy sheet metal, for example in the manufacture of bonnets and other body parts of automobiles. However, the choice of material for the aluminum alloy is limited. In particular, an AlMgSi alloy whose main alloy components are magnesium and silicon has relatively high strength in the T6 state, and at the same time has excellent forming behavior and excellent corrosion resistance in the T4 state. AlMgSi alloys include AA6XXX alloys, for example, AA6016 alloy, AA6014 alloy, AA6181 alloy, AA6060 alloy, and AA6111 alloy. Conventionally, an aluminum strip is produced from an AlMgSi alloy by casting a rolled ingot, homogenizing the rolled ingot, hot rolling the rolled ingot, and cold rolling the hot strip. The homogenization treatment of the rolling ingot is performed at a temperature of 380 to 580 ° C. for more than 1 hour. The strip is finally fed in the T4 state by a solution annealing operation typically performed at a temperature between 500 ° C. and 570 ° C., then quenched and naturally aged at about ambient temperature for at least 3 days. Can do. After quenching, it becomes T6 state by artificial aging at a temperature of 100 ° C to 220 ° C.

A hot rolled aluminum strip of an AlMgSi alloy has coarse Mg ₂ Si precipitates which are problematically broken and pulverized by subsequent cold rolling due to advanced forming. Hot strips of AlMgSi alloy are typically manufactured with a thickness of 3-12 mm and supplied to cold rolling operations with advanced formation. In the conventional hot rolling, such a phase is formed very coarsely because it passes through the temperature range where the AlMgSi phase is formed very slowly. The temperature range for forming the above phases varies depending on the alloy. However, the temperature range is 230 ° C. to 550 ° C., that is, the range of hot rolling temperature. It can be experimentally proven that this coarse phase of the hot strip has a negative effect on the elongation of the final product. This means that the formability of the AlMgSi alloy aluminum strip cannot be fully utilized.

In Patent Document 1 belonging to the same applicant, it has been proposed that the AlMgSi alloy strip has a maximum temperature of 130 ° C. immediately after leaving the final hot rolling pass and is wound at a temperature below this. The quenching of the hot strip using this method, the breaking elongation A ₈₀ of 30 percent or uniform elongation A _g at T4 condition was able to produce an aluminum strip of T4 condition is 25 percent . Furthermore, a very high value was obtained for the elongation at break in the T6 state. However, it has been found that this temperature range at the end of the final hot rolling pass results in problems with hot strip surface uniformity and thus impairs subsequent manufacturing steps. Furthermore, it was only when the production rate was reduced that the preset cooling rate could be achieved. In light of this prior art, the object of the present invention is an improved method for producing an aluminum strip from an AlMgSi alloy, which is an AlMgSi aluminum strip having very good formability in the T4 state. It is to provide a method that can be manufactured in high form.

European Patent Application Publication No. 2 270 249 (A1)

  According to the first teaching of the present invention, the stated purpose for the method is that the hot strip is above 130 ° C, preferably 135 ° C to 250 ° C, preferably 135 ° C, immediately after leaving the final hot rolling pass. This is accomplished by having the hot strip wound at this temperature.

Surprisingly, unlike the known methods using particularly low coiling temperature, in spite of the change in the coiling temperature or the mechanical properties do not change on Uniform elongation A _g to determine the formability, or negligible It became clear that it only changed. The T4 state AlMgSi alloy strip produced according to the present invention further showed a uniform elongation of more than 25% in a tensile test according to DIN EN. Furthermore, this AlMgSi alloy strip has a very good hardenability in the T6 state as can be seen from the prior application of the applicant. On the other hand, this production method can be substantially stabilized, and a higher production rate can be achieved.

  According to an advantageous embodiment of the method according to the invention, this cooling step takes place in the last two hot rolling passes, in other words above 130 ° C., preferably from 135 ° C. to 250 ° C., preferably from 135 ° C. Cooling to 230 ° C. takes place within a few seconds and at most 5 minutes. In this method, it is clear that the normal strength value and yield point value as well as the high uniform elongation value in the T4 state and the improvement of the hardenability in the T6 state are achieved in a particularly reliable manner. became.

  According to another embodiment of the method according to the invention, the working reliable cooling of the hot strip uses a hot rolling pass in which the hot strip is filled with emulsion in at least one plate cooler and itself. This is achieved by quenching at the outlet temperature. The plate cooler includes an array of cooling or lubrication nozzles that spray the rolled emulsion onto the aluminum strip. A plate cooler may be present in the hot rolling apparatus to cool the hot strip to be rolled to the rolling temperature prior to hot rolling so that even higher production rates can be achieved.

According to the next embodiment of the method, preferably when the temperature of the hot strip before the start of the cooling step performed in the last two rolling passes is at least 400 ° C, preferably 470 ° C to 490 ° C. In particular, small Mg ₂ Si precipitates can be present in the quenched hot strip, since the highest proportions of the alloy components magnesium and silicon are present in the aluminum matrix in the dissolved state. This advantageous state of the hot strip is “frozen”, in particular by a quenching operation.

  According to another embodiment of the invention, the temperature of the hot strip after the penultimate rolling pass is between 290 ° C. and 310 ° C. It has been found that at such temperatures it is possible to freeze the precipitate sufficiently and at the same time that the final rolling pass can be carried out without any problems.

  When the hot strip to be rolled has a temperature of 200 ° C. to 230 ° C. immediately after leaving the final hot rolling pass, it achieves the optimum processing speed in hot rolling without impairing the properties of the manufactured aluminum strip. can do.

  Since the thickness of the prepared hot strip is 3 mm to 12 mm, preferably 5 mm to 8 mm, a conventional cold rolling mill can be used for the cold rolling operation.

  The aluminum alloy used is preferably an AA6XXX series alloy, preferably AA6014, AA6016, AA6060, AA6111, or AA6181. All AA6XXX series alloys have the common feature that they have particularly excellent formability, such as high elongation values in the T4 state, and high after artificial aging, for example, 205 ° C / 30 minutes in the T6 state of use. Characterized by strength or yield point.

  According to another embodiment of the method according to the invention, the finished rolled aluminum strip is subjected to a heat treatment in which the aluminum strip is heated above 100 ° C. after solution annealing and quenching, and then wound up, above 55 ° C., preferably Aging at temperatures above 85 ° C. With this embodiment of the method, after natural aging, the strip or sheet metal T6 state can be obtained by a shorter heating state at a lower temperature, and the sheet metal or strip formed on the member can be used for the application. . For this, higher yield point values in the T6 state can be achieved by heating such a rapidly hardened aluminum strip to a temperature of about 185 ° C. for only 20 minutes.

The value A ₈₀ of the breaking elongation of aluminum strip produced by this embodiment of the method according to the invention, slightly less than 29% in T4 state. However, the aluminum strip produced according to the invention is further distinguished by a very good uniform elongation _Ag of more than 25% after aging in the T4 state. The term uniform elongation A _g is intended to be understood as referring to the maximum elongation of the sample that can not be observed necking sample in a tensile test. The sample thus extends uniformly in the region of uniform elongation. Conventionally, the value of uniform elongation of similar materials has been a maximum of 22% to 23%. The uniform elongation has a great influence on the formability because it determines the maximum degree of molding of the material actually used. In this connection, the method according to the invention can be used to provide aluminum strips with very good forming properties and can also be converted to the T6 state by accelerated artificial aging (185 ° C./20 minutes). it can.

The AA6016 series aluminum alloy has the following weight percent alloy components:
0.25% ≦ Mg ≦ 0.6%
1.0% ≦ Si ≦ 1.5%
Fe ≦ 0.5%
Cu ≦ 0.2%
Mn ≦ 0.2%
Cr ≦ 0.1%
Zn ≦ 0.1%
Ti ≦ 0.1%
And the balance Al, and a total of up to 0.15%, individually up to 0.05% inevitable impurities.

  If the magnesium content is less than 0.25% by weight, the strength of the aluminum strip provided for structural applications is too low, whereas if the magnesium content exceeds 0.6% by weight, the formability deteriorates. Silicon, together with magnesium, is substantially responsible for the hardenability of aluminum alloys and therefore also for example the high strength that can be achieved in applications after paint baking. When the Si content is less than 1.0% by weight, the hardenability of the aluminum strip is lowered, so that the strength in use may be slightly lowered. When the Si content exceeds 1.5% by weight, the hardening behavior of the alloy is not improved. The proportion of Fe should be limited to a maximum of 0.5% by weight to prevent coarse precipitates. Limiting the copper content to a maximum of 0.2% by weight improves the corrosion resistance of the aluminum alloy, especially in certain applications. If the manganese content is less than 0.2% by weight, the tendency to form a relatively coarse manganese precipitate is reduced. The use of chromium ensures a fine microstructure, but it is also intended to limit chromium to 0.1% by weight to prevent coarse precipitates. On the other hand, the presence of manganese improves weldability by reducing the cracking tendency or quenching sensitivity of the aluminum strip according to the present invention. When the zinc content is reduced to a maximum of 0.1% by weight, the corrosion resistance of the aluminum alloy or finished metal sheet in each application is particularly improved. On the other hand, when titanium is used, crystal grain refinement is ensured in the casting operation, but it is intended to limit the maximum to 0.1% by weight in order to ensure excellent malleability of the aluminum alloy.

AA6060 series aluminum alloys have the following weight percent alloy components:
0.35% ≦ Mg ≦ 0.6%
0.3% ≦ Si ≦ 0.6%
0.1% ≤ Fe ≤ 0.3%
Cu ≦ 0.1%
Mn ≦ 0.1%
Cr ≦ 0.05%
Zn ≦ 0.10%
Ti ≦ 0.1%,
And the balance Al, and a total of up to 0.15%, individually up to 0.05% inevitable impurities.

Combining precisely preset magnesium content with reduced Si content and strictly defined Fe content compared to the first embodiment, after hot rolling using the method according to the invention Provides a metal sheet with improved elongation and a higher yield point compared to sheet metal produced by conventional methods, because an aluminum alloy is produced that can particularly prevent the formation of Mg ₂ Si precipitates can do. Lowering the upper limit of the alloy components Cu, Mn and Cr further increases the effect of the method according to the invention. For the effect of the upper limits of Zn and Ti, see the description relating to the first embodiment of the aluminum alloy.

The AA6014 series aluminum alloy has the following weight percent alloy components:
0.4% ≦ Mg ≦ 0.8%
0.3% ≦ Si ≦ 0.6%
Fe ≦ 0.35%
Cu ≦ 0.25%
0.05% ≦ Mn ≦ 0.20%
Cr ≦ 0.20%
Zn ≦ 0.10%
0.05% ≦ V ≦ 0.20%
Ti ≦ 0.1%,
And the balance Al, and a total of up to 0.15%, individually up to 0.05% inevitable impurities.

AA6181 series aluminum alloys have the following weight percent alloy components:
0.6% ≦ Mg ≦ 1.0%
0.8% ≦ Si ≦ 1.2%
Fe ≦ 0.45%
Cu ≦ 0.10%
Mn ≦ 0.15%
Cr ≦ 0.10%
Zn ≦ 0.20%
Ti ≦ 0.1%,
And the balance Al, and a total of up to 0.15%, individually up to 0.05% inevitable impurities.

AA6111 series aluminum alloys have the following weight percent alloy components:
0.5% ≦ Mg ≦ 1.0%
0.7% ≦ Si ≦ 1.1%
Fe ≦ 0.40%
0.50% ≦ Cu ≦ 0.90%
0.15% ≦ Mn ≦ 0.45%
Cr ≦ 0.10%
Zn ≦ 0.15%
Ti ≦ 0.1%,
And the balance Al, and a total of up to 0.15%, individually up to 0.05% inevitable impurities. Alloy AA6111, in principle, has a higher strength value due to the higher copper content in the use T6 state, but must be classified as susceptible to corrosion.

  All the aluminum alloys described are specially adapted for their alloy composition according to various applications. As already mentioned, these aluminum alloy strips produced using the method according to the invention have excellent uniform elongation values, especially in the T4 state, and yield after artificial aging, for example at 205 ° C./30 minutes. The point rises particularly noticeably.

  This is also true for aluminum strips in the T4 state that have been heat treated after solution annealing.

  The above objective is for vehicle, aircraft or railway vehicle engineering because the excellent formability in the T4 state, the high corrosion resistance in the use state (T6 state) and the high value of the yield point Rp0.2 are combined well. The use of the AlMgSi alloy strips produced by the method according to the invention for parts, chassis or structural parts or panels, in particular as automotive parts, chassis parts, outer or inner panels, preferably as body parts. This is achieved by the teaching contents of 2. In particular, visible body members, such as bonnets, mudguards, and outer shell members of railway vehicles or aircraft, benefit from a high yield point Rp0.2 and have excellent surface properties even after molding with a high degree of deformation. ing.

Therefore, a rapidly hardened AlMgSi alloy strip having excellent formability can be provided by an aluminum alloy strip manufactured according to the present invention and subjected to solution annealing after the manufacturing and subsequently subjected to heat treatment. In T4 state, as already mentioned, AlMgSi alloy strip is uniform elongation _{A g} of 25 percent, for example, the yield point Rp0.2 is 80～140MPa. With this variant, it is possible to provide an AlMgSi alloy strip that can be rapidly cured and at the same time very easy to form. Artificial aging to obtain the T6 state may be performed at 185 ° C. for 20 minutes in order to achieve the required increase in yield point.

According to the following embodiment, since the aluminum alloy strip produced by the present invention has, the rolling direction, the uniform elongation A _g 25 percent in a direction oblique to perpendicular direction and the rolling direction to the rolling direction, In particular, isotropic formability is possible.

  Preferably, the aluminum strip produced according to the present invention has a thickness of 0.5 mm to 12 mm. Aluminum strips having a thickness of 0.5 mm to 2 mm are preferably used, for example, for car body components in the construction of automobile vehicles, whereas aluminum strips having a larger thickness of 2 to 4.5 mm are, for example, automobile vehicles Used for construction chassis members. Each member may also be manufactured as a cold strip with a maximum thickness of 6 mm. Further, in certain applications, aluminum strips up to 12 mm thick may be used. Such aluminum strips with very large thickness are conventionally provided only by hot rolling.

  Next, the present invention will be described in more detail with reference to the embodiments together with the drawings.

2 shows a schematic flow diagram of an embodiment of a method according to the invention for producing strips from MgSi aluminum alloy.

  In one FIG. 1, a schematic flow diagram of an embodiment of the method according to the invention for producing strips from MgSi aluminum alloy is shown. The method has a) production and homogenization processing step of rolling ingot, b) hot rolling step, c) cold rolling step, and d) solution annealing and quenching step.

First, rolled ingot 1 is alloyed with the following weight percent:
0.25% ≦ Mg ≦ 0.6%
1.0% ≦ Si ≦ 1.5%
Fe ≦ 0.50%
Cu ≦ 0.20%
Mn ≦ 0.20%
Cr ≦ 0.10%
Zn ≦ 0.20%
Ti ≦ 0.15%,
Also cast from an aluminum alloy with the balance Al and a total of up to 0.15%, individually up to 0.05% inevitable impurities.

  The rolled ingot produced by this method has a homogenization temperature of about 550 ° C. in the furnace 2 so that the alloy components added by alloying exist in a particularly uniformly dispersed state in the rolled ingot. Time homogenization is performed (FIG. 1a).

  FIG. 1 b shows how the rolling ingot 1 in this embodiment of the method according to the invention is reciprocated by a hot rolling mill 3 and hot rolled. The rolling ingot 1 during the hot rolling operation has a temperature of 400 to 550 ° C. In this embodiment, the hot strip 4 has a temperature of preferably at least 400 ° C., preferably 470 ° C. to 490 ° C. from the end of the hot rolling mill 3 to the last hot rolling pass. Preferably, the hot strip 4 is quenched using the plate cooler 5 and the work roller of the hot rolling mill 3 at this hot strip temperature. Preferably, in this example, the hot strip is cooled to a temperature of 290 ° C. to 310 ° C. before the final hot rolling pass. For this reason, the plate cooler 5 is shown only schematically, but sprays the cold rolled emulsion on the hot strip 4 to help ensure that the hot strip 4 is cooled to the aforementioned temperature. The working roller of the hot rolling mill 3 is also filled with emulsion, and the hot strip 4 is further cooled in the final hot rolling pass. In this embodiment, after the final rolling pass, the hot strip 4 has a temperature of 200 ° C. to 230 ° C. at the outlet of the plate cooler 5 ′, and is then wound up by the recoiler 6 at this temperature.

The hot strip 4 immediately after the exit of the final hot rolling pass is above 135 ° C. to 250 ° C., preferably 200 ° C. to 230 ° C., or optionally using the plate cooler 5 and the working roller of the hot rolling mill 3. since the last two hot rolling passes becomes the aforementioned temperature, despite the high winding temperature, hot strip 4 has a freezing crystalline microstructure state, uniform elongation characteristics a _g therefor T4 state 25 Very good with over%. On the other hand, because of the high winding temperature, the hot strip can be processed faster and more advantageously. A hot strip having a thickness of 3-12 mm, preferably 5-8 mm, is wound up by the recoiler 6. As already described, the winding temperature of the present embodiment is preferably 135 ° C to 250 ° C.

In the process according to the invention, there is no longer or very little coarse Mg ₂ Si precipitate that can form in the hot strip 4 being wound. The hot strip 4 has a very favorable crystalline state for subsequent processing and can be unwound from the unwinder 7, for example supplied to the cold rolling mill 9 and wound up on the recoiler 8 (FIG. 1 c).

  The resulting cold-rolled strip 11 is wound up. Thereafter, the cold-rolled strip 11 is supplied to a solution annealing operation at a temperature of 520 ° C. to 570 ° C. and a quenching operation (10) (FIG. 1d). For this reason, the cold-rolled strip 11 is rewound again from the coil 12, solution annealing and quenching are performed in the furnace 10, and the coil 13 is wound again. After natural aging at ambient temperature in the T4 state, the aluminum strip can be given maximum formability. Alternatively (not shown), the aluminum strip 11 may be divided into individual thin plates that exist in the T4 state after natural aging.

  If the aluminum strip is thicker, for example in the case of a chassis application or component, for example a brake anchor plate, a partial annealing operation may be performed instead, followed by quenching of the sheet metal.

  The aluminum strip or aluminum sheet is brought to the T6 state by artificial aging at 100 ° C. to 220 ° C. to achieve the maximum yield point. For example, the artificial aging may be performed at 205 ° C./30 minutes.

  The aluminum strip produced according to the illustrated embodiment has a thickness of, for example, 0.5 to 4.5 mm after cold rolling. Strips with a thickness of 0.5 to 2 mm are conventionally used for car body applications, or strips with a thickness of 2.0 to 4.5 mm are used for chassis members for automobile vehicle construction. In both fields of application, in most cases, even when the final product is in use (T6), a large deformation of the metal sheet is required, but a high strength is required. This is a decisive advantage in manufacturing.

  Table 1 shows the alloying components of aluminum alloys that produce aluminum strips in a conventional manner or according to the present invention. The aluminum strip contains, in addition to the stated content of the alloy components, the balance aluminum and individually up to 0.05% by weight, in total up to 0.15% by weight impurities.

  The strips (samples) 251 and 252 were used to cool and roll the hot strip from about 470 ° C. to 490 ° C. to 135 ° C. to 250 ° C. in the last two hot rolling passes using a plate cooler and the hot rolling itself. Produced using the method according to the invention. In Table 2, the measured values of these strips are indicated by “Inv.”. Thereafter, a cold rolling operation was performed to obtain a final thickness of 0.865 mm.

  Strips (samples) 491-1 and 491-11 were manufactured using conventional hot and cold rolling operations and are designated “Konv.”.

The mechanical property results shown in Table 2 clearly show the difference in achievable uniform elongation values _Ag .

  In order to obtain the T4 state, the strip was subjected to a solution annealing operation, followed by quenching and natural aging at ambient temperature for 8 days. The T6 state was obtained by artificial aging after natural aging at 205 ° C. for 30 minutes.

  The sample indicated by L was cut in the rolling direction, the sample indicated by Q was cut in a direction perpendicular to the rolling direction, and the sample indicated by D was cut in an oblique direction with respect to the rolling direction. Samples 491-1 and 491-11 were each measured in a direction perpendicular to the rolling direction.

Preferred microstructure is adjusted in the strip 251 and 252 by the method according to the present invention, although the yield point Rp0.2 and strength Rm are identical, it revealed that it is possible to substantially increase the uniform elongation A _g It was. A strip produced by the present invention as compared to the strip produced by the conventional method, uniform elongation A _g is increased to up to 26.6% from 23.0% in the direction perpendicular to the rolling direction.

The microstructures formed using the method according to the invention, and a more than 25% of high uniform elongation _{A g} and 80~140MPa very high yield point Rp0.2 is particularly advantageously combined. The T6 condition, the yield point Rp0.2 is raised to at least 185 MPa, more uniform elongation _{A g} remains at more than 12%. Furthermore, the strips produced according to the invention have a very good hardenability of ΔRp0.2 of 97 or 107 MPa.

The T6 condition, it was possible to maintain a substantially increased uniform elongation A _g by comparison with strips produced by conventional methods.

The value _{A g} and _{A 80,} a value Rm yield point values Rp0.2 and tensile strength at break elongation at each table were determined in accordance with DIN EN.

Claims (9)

The method of producing a strip from AlMgSi alloy, rolling ingot is cast from AlMgSi alloy, the rolling ingot is homogenized, the rolling ingot that is a rolling temperature is hot-rolled, pre-Symbol finished rolled strip A solution annealed and quenched method,
Immediately after leaving the hot rolling final pass, exceeds the hot strip is 130 ° C., a temperature at 250 ° C. until the hot strip is quenched to the outlet temperature, the hot strip temperature A method characterized by being wound up in The method of claim 1, wherein the hot strip is quenched to an outlet temperature using at least one plate cooler and the hot rolling pass itself filled with emulsion. The method according to claim 1 or 2, characterized in that the temperature of the hot strip is above 400 ° C before the start of the cooling step. The method according to any one of claims 1 to 3, characterized in that the temperature of the hot strip after the penultimate rolling pass is above 250 ° C. The method according to any one of claims 1 to 4, characterized in that the temperature of the hot strip after the final rolling pass before being wound is between 200C and 230C. The method according to claim 1, wherein the thickness of the prepared hot strip is 3 mm to 12 mm . The aluminum alloy is characterized by a AA6XXX system alloy, the method according to any one of claims 1-6. The finished rolled aluminum strip, wherein the aluminum strip from being performed heat treatment is heated to 100 ° C. than after solution annealing and quenching, is wound, characterized in that it is aged at 55 ° C. greater than the temperature The method according to any one of claims 1 to 7. Automobiles, aircraft or rail vehicle engineering members, the chassis or structural part or panel, in particular members of automotive engineering, as chassis parts, outer or inner panel, the method according to any one of 請 Motomeko 1-8 Use of aluminum strip manufactured by.

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