JPH0588301B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field This invention is applicable to JIS2000 series, 6000 series or
The present invention relates to a method of manufacturing an aluminum alloy material having fine grains made of a heat-treatable aluminum alloy for drawing, typified by the No. 7000 series, and in particular to a method of manufacturing an aluminum alloy material optimal for superplastic working materials. BACKGROUND OF THE INVENTION In recent years, techniques for performing superplastic working using the superplastic phenomenon of metal materials having fine crystal grains have been attracting attention. The superplastic phenomenon caused by fine crystal grains is also observed in heat-treated aluminum alloys for drawing, and when the crystal grains are reduced to 25 μm
It is known that if it is made as fine as possible, it will exhibit superplasticity when processed in a predetermined superplastic temperature range. Conventionally, methods for manufacturing heat-treated rolled aluminum alloy sheets with grains fine enough to enable such superplastic working include (a) precipitating coarse particles of intermetallic compounds through overaging treatment; A method of applying strain through warm working (e.g., JP-A-53-132420); (b) A method of rapidly cooling after solution treatment and applying strain through cold rolling (e.g., JP-A-60-86251); (c) A method of gradually cooling from the solution treatment temperature and cold rolling (Japanese Patent Application Laid-open No. 125354/1983) is known. Problems to be Solved by the Invention Among the methods for producing aluminum alloy rolled sheets having fine grains as described above, method (a) has low productivity due to overaging treatment and warm working. The problem is that it has no choice but to become low. Further, in the method (b), the crystal grains can be made finer, but there is a problem that rolling after solution treatment and rapid cooling becomes difficult. Furthermore, although the method (c) has good rolling properties, there is a problem in that intense cold working of 90% or more is required to obtain fine grains. This invention was made against the background of the above circumstances, and it is possible to practically obtain a material having fine crystal grains suitable for superplastic working without causing problems such as a decrease in productivity and a decrease in cold rollability. The purpose is to provide a method that can be used. Means for Solving the Problems The method of the present invention basically consists of coarsely precipitating precipitated particles by slow cooling from a temperature near the solution treatment temperature, and using these as recrystallization nuclei. By quenching at a temperature range of 40 to 80% of the solution treatment temperature, cold rollability is improved compared to when quenching is performed from the solution treatment temperature, and part of the solute is dissolved in solid solution or in the GP zone. This method increases the dislocation density and deformation bands in the matrix during subsequent cold rolling, thereby increasing the frequency of nucleation during recrystallization and making the crystal grains finer. Specifically, the method of the first invention is a heat-treated aluminum alloy for drawing, and Mn0.05~
1.5%, Cr0.05~0.4%, Zr0.05~0.3%
The material is made of an aluminum alloy containing one or more of the following: hot-rolled, and then heated to a temperature of 80% or more of the solution treatment temperature of the alloy.
Hold for 0.5-24 hours and 0.001-0.05 from that temperature
Solution treatment temperature 40-80% with cooling rate of °C/sec
temperature, then immediately or held at that temperature for 24 hours, then cooled at a cooling rate of 0.1°C/sec or more to 180°C or less, preferably room temperature, and then cooled at a processing rate of 60% or more. After the preliminary working, the alloy is heated to a temperature higher than the recrystallization temperature by 1℃/
This method is characterized by recrystallization by raising the temperature at a heating rate of sec or more. Further, the method of the second invention is a wrought aluminum alloy, in which Mn0.05 to 1.5% and Cr0.05 to 0.4% are used.
%, Zr0.05 to 0.3%, the material is made of an aluminum alloy containing one or more types of Zr, and after hot rolling the material, it is heated to a temperature of 80% or more of the solution treatment temperature of the alloy. and hold for 0.5-24 hours,
followed by cooling to room temperature at a cooling rate of 0.001 to 0.05 °C/sec, then reheating to a temperature of 40 to 80% of the solution treatment temperature, followed by immediate or holding at that temperature for no more than 24 hours; Cooling to 180°C or less, preferably room temperature, at a cooling rate of 0.1°C/sec or more,
After that, after performing cold working at a processing rate of 60% or more,
The alloy is characterized by being recrystallized by raising the temperature to a temperature higher than the recrystallization temperature of the alloy at a heating rate of 1° C./sec or higher. Function First, the aluminum alloy targeted by this invention will be explained. The method of this invention applies Al-Cu alloy (JIS2000 series), Al-Mg-Si alloy (JIS6000 series), Al-Zn
- It is applicable to all heat-treatable alloys for expansion, such as Mg-based alloys (JIS7000 series).
However, Cu, Mg and Si, or Zn, which are normally contained in these heat-treatable alloys,
In addition to Mg, etc., especially Mn0.05 as an essential component.
-1.5%, 0.05-0.4% of Cr, and 0.05-0.3% of Zr must be contained. In other words, Mn, Cr, and Zr are all elements that are effective in refining crystal grains through the formation of intermetallic compound precipitated particles, and by including them, fine crystals that can be thermoplastically processed as the object of this invention can be produced. It becomes possible to obtain tissue. Here, if the content of Mn, Cr, or Zr is less than 0.05%, it will be difficult to obtain fine crystal grains;
Mn1.5% or more, or Cr0.4% or more, or Zr0.3
% or more, these elements will not be sufficiently dissolved in solid solution during casting, resulting in the generation of giant intermetallic compounds, making it impossible to obtain sufficient elongation. Therefore Mn
is 0.05-1.5%, Cr is 0.05-0.4%, Zr is 0.05-0.3
It was set within the range of %. Note that heat-treatable alloys for drawing are used in the broadest sense here, and as mentioned above, 2000 series alloys, which are Al-Cu alloys, such as JIS standard and AA
Standard 2014 alloy, 2017 alloy, 2024 alloy, 2219 alloy, or 6000 series alloy which is Al-Mg-Si alloy, such as JIS standard 6061 alloy, and even Al-
7000 series alloy, which is a Zn-Mg alloy, e.g. 7075
alloy, 7475 alloy, 7N01 alloy, 7003 alloy, etc.
In the case of this invention, as mentioned above, Mn, Cr,
The composition of components other than Zr is not particularly limited as long as it can be heat treated, and may be determined depending on the application and required properties. For example, Al-
In the case of Cu-based alloys, it contains about 1.5 to 6.8% Cu, and if necessary, about 0.2 to 1.8% Mg and 0.2% Si.
It is sufficient that the content is approximately 1.3%, and Al
-In the case of Mg-Si alloy, Si is about 0.20 to 1.2%,
It is sufficient to contain about 0.35 to 1.5% Mg, and if necessary, about 0.10 to 0.40% Cu, and in the case of Al-Zn-Mg alloys, Zn is about 0.8 to 6.1%.
%, Mg in an amount of about 0.5 to 2.9%, and further Cu in an amount of about 1.2 to 2.0% as necessary. Next, the process in the method of this invention will be explained. First, an ingot of a heat-treated aluminum alloy containing one or more of Mn, Cr, and Zr as described above is produced by continuous casting or semi-continuous casting according to a conventional method. Next, after homogenization treatment is performed as necessary, hot rolling is performed according to a conventional method to obtain a required thickness. Then, the target alloy is solution-treated at a temperature of 80°C.
% or more (however, 80% or more of the temperature in degrees Celsius; all percentages below are the same), hold at that temperature for 0.5 to 24 hours, and from that temperature 0.001 to 0.05
40-80% of solution treatment temperature with cooling rate of °C/sec
(in the case of the first invention) or gradually cooled to room temperature (in the case of the second invention). By heating and maintaining the temperature at 80% or more of the solution treatment temperature, that is, at a temperature close to the solution treatment temperature, elements such as Mn, Cr, and Zr are sufficiently dissolved, and the following 0.001~ By slow cooling at a cooling rate of 0.05° C./sec, coarse particles of intermetallic compounds such as MnAl ₆ , Cr ₂ Mg ₃ Al ₁₈ , and ZrAl ₃ are precipitated. Here, if the heating and holding temperature is less than 80% of the solution treatment temperature of the alloy, sufficient solid solution cannot be achieved. Further, if the subsequent cooling rate exceeds 0.05°C/sec, precipitation of coarse particles will be insufficient, while if the cooling rate is less than 0.001°C/sec, productivity will be inhibited and this will be economically disadvantageous. Note that the solution treatment temperature here is the temperature between the solidus temperature and the solubility curve in the α phase region of the target alloy, and the specific optimum temperature varies depending on the alloy composition, but typically is AA standard or
Typical solution treatment temperatures are shown in the JIS standard, and according to this, for 2014 alloy, it is 495-505℃,
495-510℃ for 2017 alloy, 2024 alloy (plate material)
490~500℃, 515~550℃ for 6061 alloy, 460~500℃ for 7075 alloy (plate material), 460~499 for 7475 alloy
℃, approximately 450℃ for 7N01 alloy is said to be optimal.
Therefore, in the present invention, X% of the solution treatment temperature is preferably X% of the optimal solution treatment temperature of each alloy as described above. As mentioned above, slowly cool from a temperature of 80% or more of the solution treatment temperature at a cooling rate of 0.01 to 0.05 °C/sec,
When the temperature range reaches 40 to 80% of the solution treatment temperature, immediately cool from that temperature to 180 °C or less, preferably room temperature, at a cooling rate of 0.1 °C/sec or more for quenching, or to the treatment temperature
After holding for within 24 hours, quenching is performed by cooling to 180°C or less, preferably room temperature, at a cooling rate of 0.1°C/sec or more. In addition, in the case of the second invention, as mentioned above, from a temperature of 80% or more of the solution treatment temperature to 0.001~
After slowly cooling to room temperature at a cooling rate of 0.05℃/sec, reheat to a temperature of 40 to 80% of the solution treatment temperature and either immediately from that temperature or after holding it at that temperature for less than 24 hours. Quenching is performed by cooling to 180°C or less, preferably room temperature, at a cooling rate of 0.1°C/sec or more. In this way, by quenching from a temperature range of 40 to 80% of the solution treatment temperature of the target alloy, cold rollability can be improved in the case of complete quenching (when quenching is performed from the solution treatment temperature).
Moreover, part of the solute is precipitated as a solid solution or fine particles such as GP zones, and the dislocation density and deformation bands in the matrix are increased during subsequent cold rolling, resulting in a reduction in the density during subsequent recrystallization. This increases the frequency of recrystallization nuclei and ultimately makes it possible to obtain a fine grain structure. If quenching is performed at a temperature higher than 80% of the solution treatment temperature, the quenching will be too high and hard, making the next cold rolling difficult;
When quenching is performed from a lower temperature, the coarse precipitated particles are not sufficiently dissolved or refined, resulting in a low dislocation density and no effect of grain refinement. Furthermore, if the cooling rate for quenching is less than 0.1° C./sec, quenching will not occur sufficiently, strain will not be introduced sufficiently during subsequent rolling, and grain refinement will not be achieved. In addition, the temperature at the end of quenching should be 180°C or less, and if possible, it is desirable to quench to room temperature. If quenching is completed at a temperature higher than 180°C, coarse precipitates will be formed during subsequent cooling, and no quenching effect will be observed. The lower the temperature at the end of quenching, the greater the amount of solute that dissolves in the matrix or precipitates as fine particles, and the subsequent cold rolling increases the dislocation density and deformation bands in the matrix, ultimately resulting in a fine grain structure. Easy to get. After quenching at a temperature of 40 to 80% of the solution treatment temperature, cold working such as cold rolling is performed at a processing rate of 60% or more. This cold working is intended to introduce strain and refine the crystal grains during subsequent recrystallization. If the processing rate is less than 60%, the introduction of strain will be insufficient and the grains will not be refined enough. I can't plan on it. After the above-mentioned cold working, the temperature is raised above the recrystallization temperature of the target alloy at a heating rate of 1°C/sec or more,
recrystallize. During this recrystallization, the faster the heating rate is, the more advantageous it is to refine the recrystallized grains, and if the heating rate is less than 1°C/sec, fine grains suitable for superplastic processing cannot be obtained. Speed 1℃/sec
limited to the above. In order to rapidly heat at 1°C/sec or more in this way, it is necessary to use a salt bath,
A continuous air heating furnace may be used. Although the recrystallization temperature differs depending on the type of alloy, the solution treatment temperature of the alloy is always higher than the recrystallization temperature, so in actual operation, heat should be aimed at the solution treatment temperature. It is sufficient. Furthermore, after heating for recrystallization, water quenching may be performed in accordance with a conventional method. As mentioned above, the solution treatment temperature after hot rolling is
After heating and holding at a temperature range of 80% or more, 0.001~
The coarse intermetallic compound particles are once precipitated into coarse particles by slow cooling at a cooling rate of 0.05℃/sec, and then quenched at a cooling rate of 0.1℃/sec or more from the temperature range of 40 to 80% of the solution treatment temperature. By precipitating a part of the solute as a solid solution or fine particles, and then recrystallizing after performing cold working of 60% or more, it is possible to significantly refine the recrystallized grains.
Here, a very large processing rate is not required for cold working to introduce strain before recrystallization, and as mentioned above, if the processing rate is 60% or more, fine crystal grains can be obtained in the end. , cold working can be carried out without reducing productivity or causing difficulties in cold rolling. Examples [Example 1] Regarding alloys 1 to 5 having the component compositions shown in Table 1,
A 400mm thick slab was cast using the DC casting method. The obtained slab was subjected to homogenization treatment and hot rolling under the conditions shown in Table 2 to obtain a 6 mm thick hot rolled plate. Next, each hot-rolled sheet was subjected to condition symbols A~ shown in Table 3.
Intermediate annealing was performed under the conditions of I, and cooling was performed under the same conditions shown in Table 3. The alloys were then rolled at a cold rolling rate of 80%, rapidly heated in a salt bath to the solution treatment temperature of each alloy for recrystallization, held for 10 minutes, and then water quenched. In addition, some of Alloy 1 was subjected to intermediate annealing and cooling under condition code A.
After rolling with a cold rolling rate of 80%, 0.01 as a comparative method
It was recrystallized by raising the temperature at ℃/sec (symbol I). As a result of examining the crystal grain size of the plate surface of the final plate after recrystallization obtained as described above, the results shown in Table 4 were obtained. From Table 4, it is clear that the rolled sheets of invention alloys 1 to 4 containing the required amount of Mn, Cr, or Zr treated under the conditions specified in this invention all have extremely small crystal grain sizes of 10 μm or less. and
It has been found that these rolled plates can be sufficiently subjected to superplastic working. On the other hand, when Comparative Alloy 5, which does not substantially contain Mn, Zr, and Cr, was treated within the condition range of the present invention (condition symbol E), the crystal grain size became as large as 35 μm. Condition code F means that the intermediate annealing temperature is lower than 80% of the solution treatment temperature and 40% of the solution treatment temperature.
% to 80% temperature range is not more than 0.1℃/sec, and in this case, the crystal grain size is
It grew to 25μm. Furthermore, condition code G is an example in which the cooling after intermediate annealing is complete quenching from a high temperature of 480°C, and in this case, cold rolling with a rolling reduction of 80% is impossible. Condition code H indicates that quenching from 40 to 80% of the solution treatment temperature (cooling of 0.1°C/sec or more) is not performed, and condition code I indicates that the temperature is between hot rolling and cold rolling. Intermediate annealing was not performed, and the crystal grain size was as large as 30 to 32 μm in these cases as well.
Further, condition code J is an example in which heating for recrystallization quenching was performed by slow temperature increase, and in this case, the crystal grain size became coarse to 320 μm.

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[Table] [Example 2] For Alloy 1 and Alloy 2 in Table 1 of Example 1, slabs were cast in the same manner as in Example 1, and then the second
Homogenization treatment and hot rolling were performed according to the table. 480 for alloy 1 that hot rolled coil
℃ x 2 hours and cooled to room temperature at 0.01℃/sec, then the coil was continuously heated to 300℃,
It was held for 3 minutes and water cooled on the exit side of the furnace. Also alloy 2
For this, a hot rolled coil was annealed at 450°C for 2 hours and cooled to room temperature at a rate of 0.04°C/sec, and then the coil was continuously passed through a furnace maintained at 300°C and cooled with water on the exit side. These alloy 1 and alloy 2 coils were cold rolled to a thickness of 1.2 mm, and then heated to 480°C for alloy 1 and 490°C for alloy 2 at a heating rate of 20°C/sec using a continuous furnace. Continuous recrystallization quenching was performed by passing the plate through the plate for 7 minutes and cooling it with water on the exit side. When the crystal grain size on the surface of the final plate obtained was examined, it was found to be 12 μm for Alloy 1 and 13 μm for Alloy 2.
It was found that all of them had a fine grain structure. [Example 3] Regarding alloy 3 in Table 1 of Example 1, Example 1
Homogenization treatment and hot rolling were performed under the same conditions as in Table 2 of Example 1, and intermediate annealing and cooling were performed under condition symbol C in Table 3 of Example 1. after that,
Cold rolling was performed at three different cold rolling ratios: 55%, 75%, and 90%, and then, as in Example 1, the material was heated in a salt bath for recrystallization. Table 5 shows the grain size of the final plate in Example 3 in correspondence with the cold rolling rate.

[Table] Effects of the Invention According to the method of the present invention, an aluminum alloy rolled sheet having fine grains suitable for superplastic working can be obtained.
Fine grains can be obtained without significantly increasing the cold working rate and without overaging or warm working, which reduces productivity and makes cold working difficult. It has now become possible to produce rolled aluminum alloy sheets that are practically suitable for superplastic working on a mass-production scale without any problems.

Claims (1)

[Claims] 1. A heat-treated aluminum alloy for drawing, comprising:
Moreover, Mn0.05-1.5% (weight%, same below),
An aluminum alloy containing one or more of 0.05 to 0.4% of Cr and 0.05 to 0.3% of Zr is used as a material, and after hot rolling the material, 80% of the solution treatment temperature of the alloy is applied. Heat to a temperature of 0.5 to 24
from that temperature at a cooling rate of 0.001 to 0.05 °C/sec to a temperature of 40 to 80% of the solution treatment temperature, and then immediately or after holding at that temperature for no more than 24 hours, cool to 0.1 °C. After cooling to 180°C or less, preferably room temperature, at a cooling rate of 1°C/sec or more, and then cold working at a processing rate of 60% or more, the alloy is cooled to a temperature of 1°C/sec or more at a cooling rate of 1°C/sec or more. A method for producing an aluminum alloy material having fine crystal grains, which comprises recrystallizing the material by increasing the temperature at a heating rate. 2. It is an aluminum alloy for drawing, and
After hot-rolling an aluminum alloy containing one or more of Mn0.05-1.5%, Cr0.05-0.4%, and Zr0.05-0.3%,
Heating to a temperature above 80% of the alloy's solution treatment temperature and holding for 0.5 to 24 hours, followed by 0.001 to 0.05
Cool to room temperature at a cooling rate of °C/sec, then reheat to a temperature between 40 and 80% of the solution treatment temperature, followed by immediate or no more than 24 hours at that temperature, then 0.1 °C/sec. 180℃ at a cooling rate of over 180℃
Below, preferably cool down to room temperature, then process rate
Aluminum having fine crystal grains, which is characterized by being cold-worked by 60% or more and then recrystallized by raising the temperature to a temperature higher than the recrystallization temperature of the alloy at a heating rate of 1°C/sec or higher. Method of manufacturing alloy materials.