KR20150076151A - Highly malleable and igc-resistant almg strip - Google Patents

Abstract

The present invention relates to a cold-rolled aluminum alloy strip made of AlMg aluminum alloy and a method of manufacturing the same. In addition, suitable parts made of the aluminum alloy strip are disclosed. It is an object of the present invention to design a single-layer aluminum alloy strip capable of producing large area deep-drawing parts, such as internal parts of an automotive door, having sufficient intercalation corrosion resistance and excellent ductility. The object of the present invention is attained by the above-mentioned object of the present invention, wherein Si ≤ 0.2 wt%, Fe ≤ 0.35 wt%, Cu ≤ 0.15 wt%, 0.2 wt% ≤ Mn ≤ 0.35 wt%, 4.1 wt% ≤ Mg ≤ 4.5 wt%, Cr ≤ 0.1 wt% 0.25 wt.%, Ti? 0.1 wt.%, And the remainder being Al and unavoidable impurities, the maximum amount of each unavoidable impurity being 0.05 wt.% And the total amount of inevitable impurities being 0.15 wt.% Maximum. Lt; / RTI > The aluminum alloy strip has a recrystallized microstructure, the grain size of the microstructure is 15 탆 to 30 탆, preferably 15 탆 to 25 탆, and the final softening annealing of the aluminum alloy strip is performed in a continuous furnace.

Description

{HIGHLY MALLEABLE AND IGC-RESISTANT ALMG STRIP}

The present invention relates to cold rolled aluminum alloy strips made of AlMg aluminum alloys, and to a method of making such aluminum alloy strips. Further, corresponding parts made of such an aluminum alloy strip are also proposed.

Aluminum-magnesium (AlMg) alloys of the AA 5xxx series in sheet or plate or strip form are used to weld and join structures in ships, cars and planes. Aluminum-magnesium- (AlMg) -alloys of the AA 5xxx series have the property of increasing strength as the magnesium content increases. Alcg-alloys of the AA 5xxx series with an Mg content of more than 3%, especially more than 4%, tend to increase intercrystalline corrosion when exposed to high temperatures. At a temperature of 70-200 ° C, a β-Al ₅ Mg ₃ phase called β-particles precipitates along the grain, which are selectively soluble in the presence of corrosive media. As a result, the AA5182 series aluminum alloy (Al4.5% Mg0.4% Mn), which is excellent in strength properties and particularly excellent in moldability, has a heat-stress region in which a corrosive medium such as water- Can not be used. In particular, this is typically associated with vehicle parts that are subjected to cathode dip painting (CDP) and dried in a stubbing process, and conventional aluminum alloy strips in the stubbing process may be susceptible to ingress corrosion. It should also be considered when manufacturing parts for subsequent use in automotive applications and subsequently stressing the components.

The sensitivity to ingress corrosion is usually checked by a standard test according to ASTM G67 (NAMLT test). During the test, the specimens are exposed to nitric acid and the mass loss due to intergranular corrosion is measured. According to ASTM G67, the mass of material lost due to ingress corrosion is over 15 mg / cm2.

Metal sheets used in the automotive industry such as interior door parts should have very good formability. Here, the specification required for the material is determined by the rigidity of the part that plays a subsidiary role with the strength of the material. For example, parts such as doors incorporating window frames often undergo a multistage molding process.

In addition to corrosion resistance, the formability of AlMg aluminum alloys is also a major factor affecting the availability of these materials. For example, so far known materials can not be used for the sidewalls of an automobile manufactured by deep-drawing a single sheet, which means that it can not be used for the reconstruction of the automobile sidewall and for further processing steps.

For example, the forming behavior can be measured by an Erics' capping test (DIN EN ISO 20482) stretch drawing test. In the Erics' capping test, the specimen is cold pressed by pressing the sheet. During the cold forming, the force and the force variation applied to the specimen are measured until the load drops by the occurrence of cracks. The SZ32 stretch drawing measurement referred to in this application is made using a Teflon dip-drawing film to reduce friction, with a punch head diameter of 32 mm and a die diameter of 35.4 mm. Further, the measurement of the deep drawability is performed by a so-called plain-strain-coupping test using a punch having a punch diameter of 100 mm and using a horn shape according to DIN EN ISO 12004. To this end, the depth of the crack is used as a measure of the formability of the material, so the specimen of a specific shape is subjected to a drawing test until a crack appears.

Composites composed of an AA5xxx aluminum alloy having a high Mg content and having a corrosion resistant aluminum alloy layer formed on its periphery have problems in that the manufacturing process is complicated and the joining points where the aluminum composite joins other parts such as cutting edges, Out, the risk of corrosion increases.

Accordingly, the present invention relates to a single-layer aluminum material. SUMMARY OF THE INVENTION It is an object of the present invention to provide a single-layer aluminum alloy strip which is sufficiently resistant to ingress corrosion and has excellent formability and which can provide sufficient strength to large-area deep drawing parts such as automobile interior parts . Also disclosed is a method by which a single layer aluminum alloy strip can be produced. Finally, parts made of an aluminum alloy strip according to the present invention are presented.

According to a first teaching of the present invention, the above-

A cold rolled aluminum alloy strip composed of AlMg aluminum alloy,

The above-

      Si? 0.2% by weight,

      Fe? 0.35% by weight,

      Cu? 0.15% by weight,

0.2% by weight? Mn? 0.35% by weight,

4.1% by weight < = Mg < = 4.5%

      Cr ≤ 0.1 wt%

      Zn? 0.25% by weight,

      Ti < 0.1 wt%, and

The remainder contains Al and unavoidable impurities, the maximum amount of each unavoidable impurity being 0.05 wt.% And the total amount of unavoidable impurities being 0.15 wt.% At maximum. The aluminum alloy strip has a recrystallized microstructure and the grain size of the microstructure is 15 to 30 Mu] m, preferably between 15 [mu] m and 25 [mu] m, characterized in that the final soft annealing of the aluminum alloy strip is carried out in a continuous furnace.

In the specification range of the AA5182 series of aluminum alloys, the area of a particular narrow alloy component, which exhibits extremely good molding behavior while providing sufficient resistance to ingress corrosion in view of the specific constraints, such as the average grain size and the type of final softening annealing, And that there existed. In particular, the combination of the aluminum alloy components of the aluminum alloy strip and the average grain size means that the large-area shape with sufficient strength can be achieved to such an extent that the aluminum product of the deep-drawing sheet can be produced . In particular, by using a continuous furnace rather than a conventional coil annealing performed in a chamber furnace, the moldability can be further increased considerably.

According to a first aspect of the aluminum alloy strip of the present invention, the aluminum alloy comprises one or more of the following alloying elements:

0.03 weight%? Si? 0.10 weight%

             Cu ≤ 0.1 wt%, preferably 0.04 wt% ≤ Cu ≤ 0.08 wt%

             Cr ≤ 0.05% by weight,

        Zn? 0.05% by weight,

0.01% by weight? Ti? 0.05% by weight.

By limiting the alloy content of copper to a maximum of 0.1 wt%, the corrosion resistance of the aluminum alloy strip is improved. When the Cu content is 0.04 wt% to 0.08 wt%, the copper contributes to increase the strength, but the corrosion resistance is not abruptly lowered. If the silicon, chromium, zinc and titanium components are contained in a larger amount than the prescribed value, the moldability of the aluminum alloy deteriorates. The silicon content present in the alloy in the range of 0.03 to 0.1 wt.%, In combination with the iron and manganese present in the abovementioned amounts, allows the compact particles of the four-component? -Al (Fe, Mn) Si- So that the strength is increased without adversely affecting other physical properties such as moldability and corrosion behavior of the aluminum alloy.

Typically, titanium is added during continuous casting of the aluminum alloy, for example as a titanium boride wire or as a grain refinement agent in the form of a rod. Accordingly, in a further embodiment, the aluminum alloy contains at least 0.01% by weight of the Ti component.

Aluminum alloys can have one or more of the following alloying elements to further improve corrosion behavior and formability.

             Cr ≤ 0.02% by weight,

        Zn? 0.02 wt%.

If the chromium component is less than 0.05 wt% of the contamination threshold, it will significantly affect the formability of the aluminum alloy strip, so chromium should be contained in the aluminum alloy of the aluminum alloy strip according to the invention as little as possible. In order not to compromise the general corrosion behavior of the aluminum alloy strip, the zinc content is set at less than 0.05 wt.%, The contamination threshold.

In addition, it was found that the iron in the range allowed for the aluminum alloys of the AA5182 series affects the formability in association with the silicon and manganese content described above. In order for the iron component to contribute to the thermal stability of the aluminum alloy strip in combination with silicon and manganese, the iron content of the aluminum alloy strip is preferably 0.1 wt% to 0.25 wt% or 0.1 wt% to 0.2 wt%.

The same applies to the Mn component in the further constitution of the aluminum alloy strip. In order to optimize the moldability of the aluminum alloy strip, Mn is preferably 0.20% by weight to 0.30% by weight.

According to a further configuration of the aluminum alloy strip, if the Mg content is between 4.2 wt.% And 4.4 wt.%, A very good compatibility can be achieved between the high strength properties, the excellent interindustry corrosion resistance and the improvement of the molding properties.

The thickness of the aluminum alloy strip according to the following embodiment is 0.5 mm to 4 mm in order to be utilized in fields in which strength characteristics are essential. The thickness of the aluminum alloy strip is preferably from 1 mm to 2.5 mm since it is used in such a range of thicknesses in most fields where aluminum alloy strips are used.

Finally, the aluminum alloy strip according to the invention, in the automotive sector is the yield point R _{p0 .2} at least 110㎫ of the aluminum alloy strip from a soft state, the tensile strength R _m is at least 255㎫. It has been found that aluminum alloy strips having such a yield point and tensile strength are particularly suitable for automotive applications.

According to a second teaching of the present invention, the object of the present invention described above is a method of manufacturing an aluminum alloy strip according to the above-described embodiment,

- casting the rolling ingot preferably in a DC continuous casting process;

Homogenizing said rolling ingot at 480 ° C to 550 ° C for at least 0.5 hour;

- hot rolling the rolled ingot at a temperature of 280 ° C to 500 ° C;

- cold rolling the aluminum alloy strip to a final thickness at a rolling rate of 40% to 70% or 50% to 60%;

- softening the final-rolled aluminum alloy strip in a continuous furnace at 300 ° C to 500 ° C.

The above-mentioned parameters and the aluminum alloy components described above are combined to form an aluminum alloy strip having a grain size of 15 to 30 占 퐉, which has sufficient intercalation causticity, provides sufficient strength characteristics and has excellent molding properties So that it is possible to manufacture a large-area deep-drawing sheet metal part. By homogenizing the rolling ingot, the structure in the rolled hot rolling ingot is homogenized, and the alloy components are homogeneously distributed. Hot rolling at a temperature of 280 ° C to 500 ° C results in recrystallization during hot rolling, where hot rolling is typically carried out at a maximum thickness of 2.8 mm-8 mm. In all cases, the degree of rolling in the final cold rolling step is limited to 40% to 70% or 50% to 60% in order to allow recrystallization to occur across the aluminum alloy strip during soft annealing. The higher the degree of rolling of the aluminum alloy strip is, the smaller the average grain size becomes. If the degree of rolling exceeds 70% at the time of final soft annealing, the average grain size becomes too small. On the other hand, when the rolling rate is less than 40% during softening annealing, the average grain size becomes excessively large, and the formability is reduced even though the intercalation causticity is increased. Soft annealing of the finally rolled aluminum alloy strip typically takes place at a heating rate of 1-10 ° C / sec in a continuous furnace, not into a chamber where the entire coil is heated. This is because rapid heating significantly affects the later characteristics of the structure of the aluminum alloy strip. In particular, compared to annealing in a chamber furnace, moldability of the strip can be improved during soft annealing in a continuous furnace.

Alternatively, according to a further embodiment of the method of the present invention, the aluminum alloy strip may be manufactured by intermediate annealing. According to this alternative embodiment, after hot rolling, the following steps are optionally carried out:

Cold-rolling the hot-rolled aluminum alloy strip to an intermediate thickness determined by a cold rolling method to a final thickness of 40% to 70% or 50% to 60%;

- intermediate annealing the aluminum alloy strip at 300 ° C to 500 ° C;

- cold rolling the aluminum alloy strip to a final thickness at a rolling rate of 40% to 70% or 50% to 60%;

- softening the final-rolled aluminum alloy strip in a continuous furnace at 300 ° C to 500 ° C.

The intermediate annealing of the aluminum alloy strip can be carried out both in the chamber and continuously. The effect on moldability could not be measured. The crucial factor here is the rolling rate to be carried out in the final cold-rolling and whether the softening annealing of the strip takes place in a continuous furnace. This, in spite of the intermediate annealing type, determines moldability and corrosion in conjunction with the alloy component.

To prevent further microstructural changes in the wound state after soft annealing, the aluminum alloy strip according to a further construction of the method of the present invention is cooled to a maximum temperature of 100 占 폚, preferably to a maximum of 70 占 폚 after softening annealing And then wound.

As described above, in a further configuration of the method of the present invention, the intermediate annealing is performed in batch or in a continuous furnace.

When the aluminum alloy strip is cold-rolled to a final thickness of 0.5 mm to 4 mm, preferably 1 mm to 2.5 mm, the aluminum alloy strip has excellent formability, can be deep-drawn into a representative area, So that it can be used in a special application field, particularly in automobile manufacturing.

The soft annealing is preferably carried out in a continuous furnace at a metal temperature of 350 DEG C to 550 DEG C, preferably 400 DEG C to 450 DEG C for 10 seconds to 5 minutes, preferably 20 seconds to 1 minute. By doing so, the cold-rolled strip is sufficiently recrystallized thoroughly and the corresponding properties associated with very good formability and average grain size are achieved reliably and economically.

Finally, the above-mentioned object of the present invention is achieved by a vehicle component made of an aluminum alloy strip according to the present invention. These parts can be deep-drawn to a representative area, as described above, and thus can be used, for example, for large-area parts for automobiles. In addition, due to the strength properties provided for these parts, they have the requisite rigidity and corrosion resistance required for use in automobiles.

For example, a component according to a further configuration may be a body part or body accessory of the vehicle, which is subjected to thermal stress in addition to high strength specifications. Preferably, a body part such as an inner door part of a vehicle or an inner back door part can be made of an aluminum alloy strip according to the present invention.

Hereinafter, the present invention will be described in more detail with reference to the drawings.
1 is a schematic flow chart of an embodiment of a method for producing an aluminum alloy strip.
2A is a plan view of a specimen configuration for a planar-strain coupping test according to DIN EN ISO 12004;
Figure 2b is a schematic side view of a test apparatus for planar-strain coupping test in accordance with DIN EN ISO 12004;
3 is a side view of a specimen assembly for SZ32 stretch drawing measurements in an Ericsson capping test according to DIN EN ISO 20482;
Fig. 4 is a typical embodiment of a large-area metal portion deep-drawn according to the present invention.

Fig. 1 shows the sequence of an embodiment for producing an aluminum strip. The flow chart of FIG. 1 schematically shows various manufacturing steps of the aluminum alloy strip manufacturing process according to the present invention.

In step 1, a rolling ingot of AlMg aluminum alloy having the following alloy components is cast by DC continuous casting, for example.

          Si? 0.2% by weight,

      Fe? 0.35% by weight,

      Cu? 0.15% by weight,

0.2% by weight? Mn? 0.35% by weight,

4.1% by weight &lt; = Mg &lt; = 4.5%

      Cr ≤ 0.1 wt%

      Zn? 0.25% by weight,

      Ti? 0.1 wt%, and

The remainder includes Al and unavoidable impurities, the maximum amount of each unavoidable impurity being 0.05 wt%, and the total amount of impurities not exceeding 0.15 wt%.

Then, in process step 2, the ingot is homogenized. Homogenization can be performed in one or more steps. During homogenization, the rolling ingot reaches temperatures of 480 ° C to 550 ° C in at least 0.5 hours. In process step 3, the ingot is hot rolled. The hot rolling temperature is typically 280 ° C to 500 ° C. The final thickness of the hot rolled strip is, for example, 2.8 mm to 8 mm. The hot rolled strip thickness may be set to be reduced to a final thickness in a single cold rolling step 4 at a rolling rate of 40% to 70%, preferably 50% to 60%.

Then, the cold-rolled aluminum alloy strip to the final thickness is soft annealed. According to the present invention, softening annealing is performed in a continuous furnace. In the embodiment shown in Table 1, a second route through intermediate annealing is applied. To this end, the hot-rolled strip hot-rolled according to process step 3 enters cold-rolled 4a, and in the cold-rolling step the aluminum alloy strip is cold rolled to a medium thickness. The intermediate thickness is determined so that the final cold rolling rate to the final thickness is 40% to 70% or 50% to 60%. In a subsequent intermediate annealing step, the aluminum alloy strip is preferably recrystallized. The intermediate annealing is carried out continuously in the range of 400 ° C to 450 ° C or in the chamber of 330 ° C to 380 ° C.

In Figure 1, intermediate annealing is shown as process step 4b. In process step 4c according to FIG. 1, the intermediate annealed aluminum alloy strip is cold rolled to a final thickness. The rolling rate in process step 4c is 40% to 70% or 50% to 60%. Then, the aluminum alloy strip is again transformed into a soft state by softening annealing. According to the present invention, softening annealing is carried out in a continuous furnace at 400 캜 to 450 캜. The annealing in the comparative examples described in Table 4 was carried out in a chamber (KO) at 330 캜 to 380 캜. During various attempts, in addition to various aluminum alloys, various rolling rates were set after the intermediate annealing. The values of the rolling rate after the intermediate annealing are as shown in Tables 1 and 4. The average grain size of the soft annealed aluminum alloy strip was measured. For this, the profile was anodized according to the Barker method, and then the grain size was measured microscopically according to ASTM E1382 and the average grain size was determined from the average grain size.

The aluminum alloy strip manufactured in this way, the mechanical properties listed in Table 2 and Table 5, particularly yield strength R _{p0 .2,} the tensile strength R _m, and has a uniform elongation A _g and breaking elongation A _80mm. In addition to the mechanical properties of the aluminum alloy strip measured in accordance with EN 10002-1 or ISO 6892, the average grain size according to ASTM E1382 is given in units. In addition, the corrosion resistance against ingress corrosion was measured according to ASTM G67. In the initial state (0h), heat treatment was not added. Prior to the corrosion test, various heat treatments were performed to simulate the use of aluminum alloy strips in the vehicle. To model the CDP cycle, in the first heat treatment the aluminum strip was held at 185 DEG C for 20 minutes.

In a further series of measurements, the aluminum alloy strip was stored at 80 占 폚 for 200 hours or 500 hours, and then subjected to a corrosive test. Since the formation of aluminum alloy strips or sheets may affect corrosion resistance, the aluminum alloy strips may be further stretched by about 15%, stored at the heat treatment or elevated temperature, then subjected to intercrystalline corrosion according to ASTM G67 ) And mass loss was measured.

Table 1 lists the alloying elements of four different aluminum alloys. These alloys belong to the AA5182 series aluminum alloy specification. The reference alloy consists of the currently used materials and variants 1, 2 and 3 are described for comparison. Table 1 contains details of the final annealing type, the final rolling rate and the average grain size (grain size) of the measured units. Modifications 1 and 2 only differ in the final rolling rate, which results in the formation of differently sized grains. Accordingly, Modifications 1 and 2 differ from each other in terms of a final rolling ratio of 57% under the same continuous conditions, regardless of the alloy components being almost the same. As a result, the mean grain size in Modification Example 1 is 18 μm, while the average grain size in Modification Example 1 is 33. The strip described in Table 1 is heated in a continuous furnace for 20 seconds to 1 minute to reach 400 to 450 占 폚, then cooled and wound at less than 100 占 폚. As shown in Table 2, the properties of the specimens were measured according to the DIN EN ISO standard.

As can be clearly seen from Table 2, Modified Example 1 did not reach a reliable value of 110 MPa at the yield point, and was less than 110 MPa in the diagonal measurement prescribed by the symbol D. However, in the variant 1, the measurement in the rolling direction L and in the direction Q transverse to the rolling direction _{yields the} yield point R _{p0 . 2} actually reached 110 MPa. The reference value, variant 2 and variant 3 were significantly above the lower limit of these yield points. In Modification 2, the embodiment according to the present invention reliably reached the yield point measured in all the tensile directions to 110 MPa. It can clearly be seen that variant 3 with a high manganese content of 4.95% by weight achieves the highest yield point and tensile strength. It can also be seen that the different rolling rates between Modification 1 and Modification 2 had a significant effect on not only the grain size but also the yield point significantly above 110 MPa.

는 기준 재료의 값과 크게 다르지 않다.In particular, in the modified example 2, the anisotropy of the alloy according to the present invention was lower than that of the standard, but the plane anisotropy? R was low. Herein, the planar anisotropy is defined as 1/2 * (r _L + r _Q -2 r _D ), and r _L , r _Q and r _D are the r-values in the longitudinal, transverse and / . Here, the value of average r- value computed from the 1/4 * (r _L + 2r _D + r _Q)

Is not significantly different from the value of the reference material.

Table 3 shows the measured values for intercalation corrosion. Variation 2 according to the present invention has a significant value in both stretch and unstretched conditions, particularly with respect to long-term stressing in relation to the reference measured value. Here, Modification 2 and the criterion are almost the same. Variation 3, despite having a high yield point and high tensile strength, has a high Mg content and, therefore, a significant long-term corrosion test, including a long time of 200 hours at 80 DEG C, in addition to a short time test of 20 minutes at 185 DEG C. Mass loss.

From the measurements in Table 3 relating to moldability, in particular, variant 2, it was found that the SZ32 compaction test and the plain-strain-coupping test were superior in stretch forming properties to the reference alloy. Significant improvement in the molding behavior of the aluminum alloy strip in accordance with variant 2 as compared to the reference aluminum alloy suggests that even at low Mg contents yielding significant values of yield point and tensile strength without impairing the resistance to ingress corrosion It can be said that This was especially demonstrated by the mass loss measurements performed in accordance with ASTM G67 in the NAML test. In Modification 2, it was found that the deep drawing behavior was improved by 7% in the Ericsson cupping test and by about 10% in the plane-strain cupping test, which is an advantage of the aluminum alloy strip according to the present invention, In the first place. The potential for further molding in this way can be used for large-area metal sheet parts that are deep-drawn, such as the interior door parts of a vehicle.

In the following, the test setup related to the &quot; SZ32 coffering &quot; test in accordance with DIN EN ISO 20482 and the plain-strain cupping test in accordance with DIN EN ISO 12004 is described.

Fig. 2A shows the geometrical shape of the test piece 1. Fig. The tapered specimen 1 having the cut-out portion was cut out from the circular metal sheet so that the width of the web 4 was 100 mm and the radius 2 at the waist was 20 mm. The dimension 3 of 100 mm represents the diameter of the punch. Fig. 2b shows a specimen 1 fixed between two holders 5,6. The specimen 1 placed on the mount 8 and pressed against the support by the holders 5 and 6 is pushed in the direction of the arrow by the punch 7 having a half-circle tip with a radius of 100 mm. On the side of the holder facing the mount 8, an entry radius of 5 mm or 10 mm is formed. During molding, the force at which the capping test is performed is measured and the depth of the punch is measured when a sudden drop in load is indicated, indicating crack formation.

The "SZ32 cupping" test according to Erickson has a similar setting, but no specimen with waist is used. Here, the test piece 9 is simply held between the holder 10 and the support 11, and draws the test piece 9 using the punch 12 until the load of the drawing force dips. Then measure the position of the punch. In Fig. 3, the die opening is 35.4 mm and the punch diameter is 32 mm, which means that the punch radius is 16 mm. In the SZ32 dip-drawing test, a Teflon dip-drawing film was used to reduce friction.

In Tables 4 and 5, additional embodiments and comparative examples were carried out, and mechanical properties and intercalation corrosion resistance were measured. It was found that the corrosion resistance and the mechanical characteristics can be made very excellent by using a continuous furnace and specially selecting the grain size from 15 탆 to 30 탆, preferably from 15 탆 to 25 탆. Thus, for example, in the embodiment No. 2 according to the present invention. 3, 4, 7, 11, and 15 showed an essential degree to be not only satisfy corrosion seureoul between intergranular, used in the mechanical properties R _{p0 .2} R _m and the automotive sector, so that a large-area deep-drawing It was found to be ideal for providing parts.

Fig. 4 shows an example of a body part in the form of an internal part of a door produced from a single dip-drawing sheet of the aluminum alloy strip of the present invention. Here, the sheet thickness is preferably 1.0 mm to 2.5 mm. In addition, metal sheet shell structures such as vehicle back doors, bonnets, and internal components of vehicle structures, where specifications are strictly required from the standpoints of other parts of the vehicle, formability and seamability, are also possible.

Claims (16)

A cold rolled aluminum alloy strip composed of AlMg aluminum alloy,
The above-
Si? 0.2% by weight,
Fe? 0.35% by weight,
Cu? 0.15% by weight,
0.2% by weight? Mn? 0.35% by weight,
4.1% by weight &lt; = Mg &lt; = 4.5%
Cr ≤ 0.1 wt%
Zn? 0.25% by weight,
Ti? 0.1 wt%, and
The remainder contains Al and unavoidable impurities, the maximum amount of each unavoidable impurity being 0.05 wt.% And the total amount of unavoidable impurities being 0.15 wt.% At maximum. The aluminum alloy strip has a recrystallized microstructure and the grain size of the microstructure is 15 to 30 탆, and the final soft annealing of the aluminum alloy strip is carried out in a continuous furnace. The method according to claim 1,
A cold-rolled aluminum alloy strip characterized in that the aluminum alloy has one or more of the following alloying elements.
0.03 weight%? Si? 0.10 weight%
Cu ≤ 0.1% by weight,
Cr ≤ 0.05% by weight,
Zn? 0.05% by weight,
0.01% by weight? Ti? 0.05% by weight. 3. The method according to claim 1 or 2,
A cold-rolled aluminum alloy strip characterized in that the aluminum alloy has one or more of the following alloying elements.
Cr ≤ 0.02% by weight,
Zn? 0.02 wt%. 4. The method according to any one of claims 1 to 3,
Wherein the Fe content is 0.10 wt% to 0.25 wt% or 0.10 wt% to 0.2 wt%. 5. The method according to any one of claims 1 to 4,
And a Mn content of 0.20 wt% to 0.30 wt%. 6. The method according to any one of claims 1 to 5,
And an Mg content of 4.2 wt% to 4.4 wt%. 7. The method according to any one of claims 1 to 6,
A cold-rolled aluminum alloy strip characterized in that the thickness of the aluminum alloy strip is 0.5 mm to 4 mm. 8. The method according to any one of claims 1 to 7,
Characterized in that the yield point R _{p0 .2} of a soft state of an aluminum alloy strip is at least 110㎫, the tensile strength R _m is at least 255㎫, cold-rolled aluminum alloy strip. 9. A method of producing an aluminum alloy strip according to any one of claims 1 to 8,
Casting a rolling ingot;
Homogenizing said rolling ingot at 480 ° C to 550 ° C for at least 0.5 hour;
- hot rolling the rolled ingot at a temperature of 280 ° C to 500 ° C;
- cold rolling the aluminum alloy strip to a final thickness at a rolling rate of 40% to 70% or 50% to 60%;
- softening the final-rolled aluminum alloy strip in a continuous furnace at 300 ° C to 500 ° C. 10. The method of claim 9,
After hot rolling,
Cold-rolling the hot-rolled aluminum alloy strip to an intermediate thickness which is determined so as to have a rolling rate of 40% to 70% or 50% to 60% for cold rolling to a final thickness;
- intermediate annealing the aluminum alloy strip at 300 ° C to 500 ° C;
- cold rolling the aluminum alloy strip to a final thickness at a rolling rate of 40% to 70% or 50% to 60%;
- softening the final-rolled aluminum alloy strip in a continuous furnace at 300 ° C to 500 ° C is optionally carried out. 11. The method according to claim 9 or 10,
And after the softening annealing, the aluminum alloy strip is cooled to a maximum temperature of 100 占 폚 and then wound. The method according to claim 10 or 11,
Characterized in that the intermediate annealing is carried out in batch or in a continuous furnace. 13. The method according to any one of claims 9 to 12,
Wherein the aluminum alloy strip is cold-rolled to a final thickness of 0.5 mm to 4 mm. 14. The method according to any one of claims 9 to 13,
Characterized in that softening annealing is carried out in a continuous furnace at a metal temperature of 350 DEG C to 550 DEG C for 10 seconds to 5 minutes. 9. A vehicle component made of the aluminum alloy strip according to any one of claims 1 to 8. 16. A vehicle component according to claim 15, characterized in that it is a body part or a body accessory of a vehicle.

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