JPS6050864B2 - Aluminum alloy material for forming with excellent bending workability and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aluminum alloy material for forming that has excellent bending workability and a method for manufacturing the same. The present invention relates to an aluminum-cum alloy material which has significantly improved properties and is suitable for processing automobile bodies.

Conventionally, as aluminum (Al) alloys for automobile bodies, 5182, X508 Chiang's non-heat treatment alloy; AU2
G) Heat-treatable alloys such as 203 and 2002 and 600 and 6010 have been developed and some have been put into practical use.

Comparing the mechanical properties of these alloys with those of cold-rolled steel sheets commonly used for automobile bodies, the strength, especially the tensile strength, is approximately the same, and therefore, in terms of strength, there are no practical problems as alloys for automobile bodies. However, in terms of press formability into car body parts, all of the above-mentioned known alloys have the disadvantage that the formability is inferior to that of cold-rolled steel sheets, and it is not always possible to obtain a satisfactory molded product. For this reason, the present inventors
-31858 and Japanese Patent Publication No. 56-31860.
) 0.5 to 2.0%, copper (Cu) 0.3 to 1.2%, and a proposal for an A1 alloy containing at least one of manganese, chromium, zirconium, and vanadium in trace amounts. However, this made it possible to provide high strength and excellent moldability.

However, among these alloys, as mentioned above, the conventionally known N alloy has the same strength as cold-rolled steel sheets used for automobile bodies, but in addition to its press formability, it has poor bending properties. However, the Mg-Zn-
There is still room for improvement in the bendability of the Cu-based A1 alloy, which is a problem in its actual use.

In other words, in the manufacturing process of automobile body panels,
It is common practice to join the outer panel and the inner panel by bending, but as mentioned above, the bendability of existing aluminum alloys for automobile bodies is significantly inferior to that of cold-rolled steel sheets, so aluminum for body panels is This has become a major technical problem in trying to achieve this goal.

In view of this, the present inventors have conducted various studies, and as a result, by devising various alloy components and manufacturing methods,
A1 is a Mg-Zn-Cu alloy with significantly improved bending workability without impairing the original characteristics of the alloy, such as strength, elongation, and formability. They discovered gold and a method for producing it, and arrived at the present invention. That is, the object of the present invention is to produce a practical A1 that has excellent bending workability and has strength, elongation, and excellent formability particularly suitable for use in automobile bodies. To provide an alloy and method for producing the same, 3.6 to 5.4% Mg by weight;
0.6-2.0% Zn and 0.03-0.28% C
u, 0.03-0.25% iron (Fe), 0.03
~0.20% silicon (Si) and 0.01-0.15
% of titanium (Ti), 1 to 500 ppm (7) of boron (B), and 1 to 100 ppm of beryllium (Be) (however, the content ratio of Fe/Si is within the range of 0.2 to 8). The alloy composition was adjusted so that the remainder consisted of aluminum and impurities.

Further, in the present invention, an alloy consisting of such alloy components is used, an ingot is manufactured from it, and 380-5
After single or multi-stage soaking for 2-4 hours at a temperature of 20°C, 97-99°C at a temperature of 380-500°C.
．． Hot rolling with a working degree of 8% is carried out, and then, as necessary, repeating softening and cold rolling in the middle, the 40 to 90
After final cold rolling with a working degree of 460-540%
After rapidly heating at a heating rate of 1000C/min or more to a temperature of 1000C/min and holding for 5 to (4) seconds,
By performing the quenching operation at a cooling rate of °C/sec, the desired A1 alloy material can be effectively produced, and the A1 alloy material obtained thereby has excellent bending workability. In addition, it became suitable for use as a practical automobile body material. Here, Mg as one of the main alloy components blended into A1 according to the present invention is 3.6 to 5.4% (by weight).

It is necessary to add it within the range (the same applies hereinafter), and by doing so, it is possible to significantly increase the strength of the target A1 alloy material, and it also contributes to improvements in elongation, formability, bendability, etc. . Note that if the Mg amount is less than 3.6%, this effect is not sufficient, and if the Mg amount exceeds 5.4%, problems such as reduced hot workability will occur. Moreover, Zn, which is another main alloy component, is ~. 6-2.
A blending amount of 0% imparts aging properties to the alloy, and improves strength by aging at room temperature after quenching, and coexists with Mg to improve elongation, formability, bendability, etc. of the alloy. In addition,
If the blending amount of Zn is less than the lower limit, this effect will not be sufficient, and if it exceeds the upper limit, hot workability will decrease,
This causes problems such as deterioration of elongation, formability, bendability, etc. Furthermore, Cu, one of the main alloy components, is 0.03 to 0.28
%, which, like Zn and Mg, imparts aging properties to the alloy, increases its strength, and significantly improves its bendability. And Cu
If the amount of Cu added is less than the lower limit of 0.03%, these effects will be insufficient, and if the amount of Cu added exceeds the upper limit of 0.28%, the bendability of the alloy and ,
Formability begins to deteriorate. In particular, the amount of Cu should not exceed the upper limit because it has a significant effect on the bendability and formability, especially the bending workability, when aged at room temperature after quenching.On the other hand, if the amount of Cu exceeds the upper limit, the grain boundary Cracking and stress corrosion cracking are likely to occur, and in addition, from the viewpoint of rolling workability of wide plates, the Cu content must be 0.28% or less. In addition, since Fe crystallizes as an insoluble compound and reduces bendability, elongation, formability, etc.
If it exceeds 25%, it is undesirable, and if it is less than 0.03%, the crystal grains become coarse after quenching, which is problematic. Therefore, the amount of Fe added must be limited to 0.03 to 0.25%. Si must be contained in a proportion of 0.03 to 0.20%, and it coexists with Mg and exhibits age hardening properties, but this effect is not observed at less than 0.03%. .

In addition, like Fe, Sl crystallizes as an insoluble compound, but if it exceeds its limit of 0.20%, it causes problems such as deterioration of the bendability, elongation, formability, etc. of the final alloy material. arise. And such Fe. l5S
l should be such that in the Fe/Si content ratio it is in the range 0.2-8.

When this content ratio exceeds the upper limit, the amount of Fe-based insoluble compounds increases and there is a problem that various physical properties such as bendability, elongation, and formability of the final alloy material decrease. Since the amount of Fe-based insoluble compounds becomes very small and causes problems such as coarsening of crystal grains after quenching, it must be maintained within the above range. Also,
Both Tl and B have the effect of refining the ingot structure,
This is effective in improving the hot workability of the ingot and the bendability and formability of the final product, and in the present invention,
Tl is 0.01-0.15% and B is 1-500p
It will be contained at a ratio of pm. If the amount added is less than the lower limit, the desired effect will not be sufficient, and if it exceeds the upper limit, large interalloy compounds will crystallize and deteriorate bendability, formability, etc. Undesirable. Furthermore, Be is added in a proportion of 1 to 100 ppm, thereby improving castability, hot rolling workability,
This has effects such as improving the surface condition of the plate surface during wide-width hot rolling.

If the amount of Be is less than 1 ppm, the effect will not be sufficient, and it is not preferable to add more than the upper limit of 100 ppm from the viewpoint of toxicity. Therefore, Be needs to be incorporated into the alloy in a range of 1 to 100 ppm. In the present invention, these alloy components, namely MglZn. Cu. Fe. Si. Ti. B and? is added to A1 (including impurities) within the range of the above blending amount to form an N alloy.
A practical Al alloy material suitable for use as an automobile body material has been obtained, which maintains the original characteristics of the Zn-Cu-based Al alloy and has excellent bending properties and excellent properties.

In such alloy components and composition ranges,
After the A1 alloy molten metal is prepared, a predetermined alloy ingot is cast from the molten metal according to a known ordinary method in order to obtain the target A1 alloy material, and then the obtained ingot is solidified. Heat treatment to homogenize the structure (alloy components),
So-called soaking (homogenization treatment) etc. will be performed, but in order to obtain a material that maximizes the good performance of the A1 alloy of the present invention, it is recommended to manufacture it using the following process. It is.

That is, first, soaking is performed on the N alloy ingot according to the present invention in a single or multi-stage operation at a temperature of 380 to 520° C. for 2 to 5 hours, thereby making the N alloy ingot during casting. It is desirable to infiltrate as much of the crystallized eutectic compound as possible.

If this infiltration is insufficient, the amount of compounds remaining in the final product, such as plate material, will increase, resulting in decreased bendability, elongation, formability, etc. of the final plate material, and hot processing of the ingot. This can cause problems such as decreased sexual ability. Note that if this soaking temperature is lower than 380°C, the effects of improving the various properties mentioned above will be insufficient, and if a soaking temperature exceeding 520'C is adopted, eutectic melting will occur in the ingot. This is not preferable because it causes Next, the AI alloy ingot subjected to such homogenization treatment is subjected to hot rolling.
It is preferable that the temperature of this hot rolling is in the range of 380 to 500'C, and the working degree during the hot rolling is 9.
It is desirable to set it as 7-99.8%.

When such hot rolling temperature is lower than 380'C,
The hot deformation resistance is high, making hot rolling a problem, and if it exceeds 500'C, the edge cracking of the plate end surface during hot rolling becomes large, which becomes a problem. In addition, when the degree of hot working is large, the eutectic compound remaining in the ingot after soaking is finely crushed, which improves the bendability, elongation, formability, etc. of the final plate. It is. In addition, when this working degree is less than the lower limit, the above-mentioned effect is small, and when it exceeds the upper limit, edge cracking of the plate end surface during hot rolling becomes large, which becomes a problem. After the hot rolling is completed, the material is cold rolled to a predetermined thickness while performing intermediate annealing as necessary. At that time, the final cold rolling degree is 40 to 90%. is desirable.

The greater the degree of cold rolling, the more the hot rolled structure is destroyed, and the eutectic compounds and Fe and Sj-based insoluble compounds that were finely crushed during hot rolling are crushed even more finely. This improves properties such as elasticity, elongation, and moldability. In addition, if this degree of cold rolling is less than the lower limit, the above effects will not be sufficient, and there will be a problem that the crystal grains will become coarse after quenching. In this case, the edge cracks on the end face of the plate during rolling become large, which becomes a problem. The A1 alloy material that has been subjected to such cold rolling and rolled to the desired product thickness will be further subjected to final tempering (final heat treatment) after the cold rolling process has been completed. It is desirable to perform T4 treatment under the following conditions using, for example, a continuous quenching furnace.

In addition, the solution treatment conditions for obtaining the T4 treated material, which is the final product, are as follows:
It is preferable to hold @. and,
The heating rate of the cold rolled material to this solution treatment temperature is 100
The cooling rate after the solution treatment is preferably 1000°C/sec to 2°C/sec. desirable. Note that if the solution treatment temperature and holding time are below the lower limit values, MgNzn. ．． Infiltration of additive elements such as Cu becomes insufficient, resulting in problems such as deterioration of strength, bendability, elongation, formability, etc. And the heating temperature and holding time exceed the upper limit! If this happens, the crystal grains will become coarser, which is undesirable. Furthermore, if the cooling rate after solution treatment is less than the lower limit, Mg-Zn compounds will precipitate at grain boundaries during cooling, which will adversely affect bendability, elongation, formability, strength, etc. That will happen. Furthermore, if the cooling rate exceeds the upper limit, the plate after quenching will be highly distorted, which will require straightening to remove the distortion, resulting in a problem of reduced bendability and elongation. On the other hand, if the heating rate during solution treatment is less than the lower limit, there are problems such as coarse grains and decreased hardening efficiency. The Al alloy material obtained in this way has excellent strength, elongation, and formability, as well as extremely excellent bending workability, so it can be effectively used as an automobile body panel material, and can be used as a material for outer and outer panels. Bonding by bending can also be effectively performed, making it possible to make the body panel made of aluminum.

In order to clarify the present invention more specifically, some examples of the present invention are listed below, but it goes without saying that the present invention is not limited in any way by the description of such examples. By the way.

In addition, in the examples, unless otherwise specified, all percentages are expressed on a weight basis. Example 1 300m thick with chemical composition shown in Table 1 below
fft various Al alloy ingots were prepared and heated to 490°C.
×24VI! After homogenization treatment, hot rolling was performed at a temperature of 480° C. to form a plate material with a thickness of 37 m (degree of hot working: 99%).

Next, the 3TIult plate was softened at 380°C for 2 hours, and then cold-rolled to a thickness of about 66% to a plate thickness of 1T!
r! Various cold-rolled sheets of n were prepared. Then, such 17r0
A cold rolled sheet of n thickness is heated to a temperature of 500°C using a continuous quenching furnace at an average heating rate of 800°C/min and held at that temperature for 258' followed by an average cooling of 20°C/s. The sample was cooled to room temperature at a high speed, and then aged at room temperature for 30 days to obtain an η plate.

The various performances of the various T patterns (1T1rm thickness) thus obtained were measured and the results are shown in Table 2.As is clear from the results in Table 2, alloy No. 1 according to the present invention. l
The A1 alloy material having a composition consisting of ~7 is the comparative material NO.
．． It is understood that the bending workability is not only significantly superior to that of No. 8 to No. 14, but also the formability (the higher the Erichsen value is, the better it is), etc.

Example 2 After performing various homogenization treatments (soaking) as shown in Table 3 on the various N alloy ingots shown in Table 1 above, a 17 m thick ingot was prepared under the same conditions as in Example 1. Manufactured T-rebel.

Table 3 shows the relationship between the various performances of the various T-widths obtained in this way and the homogenization processing conditions.As is clear from the results, by adopting the predetermined homogenization conditions, This makes it possible to improve the performance of the Al alloy material.

Example 3 An N alloy ingot with a thickness of 300 Tr0n consisting of various alloy components shown in Table 1 was homogenized at 480°C for 24 hours, and then rolled (hot rolled, cold rolled, etc.) under the conditions shown in Table 4 below. ) and 0
．． A cold-rolled plate with a thickness of 8 to 2 wm was obtained.

Thereafter, the cold rolled sheet was subjected to T4 under the same conditions as in Example 1.
The process was done. The performance of the various T4 plates thus obtained is shown in Table 5 below, and as is clear from this table, by adopting predetermined rolling conditions, improvement in the plate material performance and the saw layer can be achieved.

Example 4 An ingot made of the various alloy components shown in Table 1 was homogenized and hot rolled under the same conditions as Example 1. And then 1rw
It was cold rolled to a plate having a thickness of L, and then subjected to various T4 treatments under the conditions shown in Table 6 below.

The various performances of the various T4-treated plates thus obtained are shown in Table 7, and as is clear from the table, the T4-treated plates treated under the specified conditions all have better performance. This was recognized. Example 5 300Tm consisting of various alloy components shown in Table 1 above
m-thick AI alloy ingot was heated to 1T under the manufacturing conditions shown in Table 8 below. r: T-shaped with Fn thickness.

Claims (1)

[Claims] 1. 3.6 to 5.4% magnesium by weight, 0.
6-2.0% zinc, 0.03-0.28% copper,
0.03-0.25% iron, 0.03-0.20% silicon, 0.01-0.15% titanium, 1-50%
Contains 0 ppm of boron and 1 to 100 ppm of beryllium (however, the content ratio of iron/silicon is within the range of 0.2 to 8), with the remainder being aluminum and impurities. Forming process with excellent bending workability. Aluminum alloy material for. 2 by weight, 3.6-5.4% magnesium and 0.2% by weight.
6-2.0% zinc, 0.03-0.28% copper,
0.03-0.25% iron, 0.03-0.20% silicon, 0.01-0.15% titanium, 1-50%
A process of producing an aluminum alloy ingot containing 0 ppm of boron and 1 to 100 ppm of beryllium (however, the content ratio of iron/silicon is within the range of 0.2 to 8), with the remainder consisting of aluminum and impurities. and the aluminum alloy ingot was heated at a temperature of 380 to 520°C for 2 to 4 hours.
A step of performing one-stage or multi-stage soaking for a time of 97-99.degree.
A step of hot rolling with a working degree of 8%, a step of cold rolling with a working degree of 40 to 90% after such hot rolling, and then a step of rolling at a temperature of 460 to 540° C. at 100° C.
After heating at a heating rate of 1 minute or more and holding for 5 to 60 seconds,
A method for producing an aluminum alloy material for forming with excellent bending workability, the method comprising the step of quenching at a cooling rate of 1000° C./sec to 2° C./sec.