JP2001098354A - Manufacture of manganese added aluminum alloy die material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing Mn added aluminum alloy extruded die material parts in which deterioration in external appearance due to the occurrence of coarsened crystal grains after heat treatment at the surface of the extruded die material can be prevented. SOLUTION: After an Mn added aluminum alloy extruded die material is subjected, if necessary, to an annealing step, stretch forming is performed. At the recrystallization resultant from subsequent heat treatment such as solution heat treatment, crystal grains are uniformly refined. Then the extruded die material is subjected to stretch leveling and to aging treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to girders (spars) and reinforcing members (stiffeners) of auxiliary wings (flaps, ailerons, etc.) of large transport aircraft, and main wing girders, reinforcing members, and fuselage of small transport vehicles. The present invention relates to a method of manufacturing an aluminum alloy extruded part, such as a passing material (stringer) or a round frame (frame).

[0002]

2. Description of the Related Art Extruded parts made of 2000 series alloy are used in aircraft and the like. In this extruded die member, strain accumulates due to friction with the mold, the strain is released during the subsequent heat treatment, and a recrystallization phenomenon occurs.
It is well known that a coarse grain layer is formed on the surface layer as shown in FIG.

[0003] For this reason, large crystal grains appear on the surface of the extruded die part, and the appearance is strange. Representative of the 2000 series alloys used in aircraft are the 2024 alloy and the 2219 alloy having the chemical composition ranges shown in Table 1, and the characteristics of each alloy will be described below.

[0004]

[Table 1]

[0005] The above-mentioned 2024 alloy has crystal grain coarsening prevention.
Therefore, the transition element manganese (hereinafter referred to as Mn) is added
Have been. Mn is Al₇Mn or Al₂₀Cu_Two
Mn _ThreeExists, but the size during precipitation is relatively large
No. For this reason, the dislocation movement is larger than in the case of adding Cr and Zr.
The effect of stopping crystal is weak, recrystallization is likely to occur, and
Coarsening is likely to occur.

In particular, in the case of a thin extruded material, the degree of processing during extrusion is higher than that of a thick material, so that when recrystallization occurs by a subsequent heat treatment, a coarse recrystallized structure is formed over the entire cross section. There are many. Therefore, when surface treatment is performed on an extruded part made of a 2024 alloy to which Mn is added, coarsely grown crystal grains appear clearly on the surface, and the commercial value of the part is reduced as an abnormal pattern,
In some cases, extruded parts must be scrapped.

In order to prevent this, in a conventional method of manufacturing an extruded die part, it is necessary to provide a step such as sanding before the surface treatment, and to roughen the surface of the part in this step so that the crystal pattern cannot be seen. Was. However, adding such a sanding step inevitably increases the cost of manufacturing parts.

[0008]

The problem with the Mn-added 2000-series aluminum alloy extruded part is that, as described above, a non-uniform coarse structure is formed during recrystallization by heat treatment, and this is recognized as a material abnormality. It is to be.
Even in the same aviation aluminum alloy, such a phenomenon is unlikely to occur in a 7000 series alloy to which Cr or Zr is added. Therefore, the abnormal pattern due to the coarse structure gives a further sense of anxiety to those concerned. .

In the production of extruded parts made of a conventional Mn-added 2000-based aluminum alloy, a sanding step is provided before surface treatment in order to solve the above-mentioned problems. Increased, leading to lower profits. An object of the present invention is to provide a manufacturing method capable of forming a homogeneous and fine crystal structure during recrystallization and obtaining a beautiful surface appearance in order to solve the above problems.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems in the Mn-added aluminum alloy extruded die, the present invention provides a method of subjecting a hot-extruded Mn-added aluminum alloy to cold working, followed by solution treatment. Provided is a method for producing a Mn-added aluminum alloy extruded material to be subjected to heat treatment.

It is known that when a processed metal material is heated, regenerative development of a crystal called recrystallization occurs. It is known that the recrystallization development changes depending on the heating temperature, the holding time, and the degree of processing before heating. That is, when the processed metal material undergoes a heat treatment and is recrystallized, the coarsening of the crystal due to the recrystallization depends on the heating temperature and the degree of processing. There is a peak, beyond which the grains are refined.

Usually, the heat treatment temperature such as the solution heat treatment temperature of aluminum alloy and the holding time are set as heat treatment standards. Therefore, in the present invention, recrystallization after heat treatment is performed by performing cold machining. At this time, the crystal is prevented from becoming coarse.

[0013] In the usual extrusion mold material manufacturing process, heat treatment such as solution treatment is performed after hot extrusion. In the present invention, however, the step of performing cold working after hot extrusion is inserted as described above. During recrystallization that occurs during heat treatment such as solution treatment,
Control so that the crystal grains are uniformly fine. This makes it possible to obtain a Mn-added aluminum alloy extruded material having a homogeneous and beautiful surface in appearance.

The cold working performed in the method for manufacturing an extrusion member according to the present invention may be tension, compression, or rolling. However, in the case of an extrusion member, the cross section is complicated and long in the longitudinal direction. However, it is needless to say that the pulling method is practical but not limited to this.

In the case of an extruded material, after solution treatment, tension is generally applied to correct distortion, and equipment for this purpose is usually provided. Therefore, cold working is added by the present invention. It can be considered that there is no increase in equipment cost because the equipment can be used with such equipment.

In the production method of the present invention, the workability of the cold working added to the extruded die before the heat treatment is selected so that a fine and homogeneous recrystallized structure can be obtained after the heat treatment such as the solution treatment. When applying tension, the amount of tension is generally 3%
Before and after, the coarsening of the crystal grains after the heat treatment peaks,
When the tensile amount exceeds 5%, refinement of crystal grains becomes apparent.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for producing a Mn-added aluminum alloy extruded die according to the present invention will be described. FIG. 1 shows a processing diagram in one embodiment of the method for producing a Mn-added aluminum alloy extruded die according to the present invention. As can be seen in FIG. 1, the extruded mold material is subjected to an annealing step if necessary, and then subjected to a tensile work, so that crystal grains are uniformly refined at the time of recrystallization caused by a heat treatment such as a solution treatment. . After that, the extruded mold material is subjected to tensile straightening and aging treatment.

FIG. 2 shows the relationship between the amount of tensile working performed on the extruded die and the size of the crystal grains after the solution treatment, for an example of the 2219 alloy. When the amount of tensile processing is 4%, the coarsening of the crystal grains becomes the maximum, and when it exceeds that, the crystal grains become small and the refinement starts. Therefore, when the amount of tensile processing is 6% or more, a uniformly fine structure can be obtained, and the problem in appearance can be solved.

FIG. 3 shows the amount of tensile processing applied to the extruded material before heat treatment and the evaluation of the appearance rank of the obtained extruded material. As can be seen from FIGS. 2 and 3, the tensile work amount is required to be 6% or more. However, depending on the cross-sectional shape of the extruded material, there may be a case where the coarsened layer becomes deep and 6% uniform tensile work cannot be given. . In this case, it is necessary to apply a post-extrusion annealing treatment to improve the elongation of the material and to give a tensile work of 6% or more. Note that the finer and more uniform structure can be obtained as the amount of tensile processing increases, but if it exceeds 10%, the structure may be broken. Therefore, 6 to 10% is appropriate.

Further, in this embodiment, the annealing process is performed before the tensioning process, but it is not always necessary to insert the annealing process. When performing the annealing process,
After heating to 420 ° C., this is carried out by slow cooling in a furnace (the extruded material of the 2219 alloy used in FIG. 2 is annealed).

[0021]

As described above, the Mn according to the present invention
In the manufacturing method of the added aluminum alloy extruded die, the hot extruded die is subjected to a cold working such as a tensile working of 6 to 10% and then to a heat treatment. By this cold working,
This suppresses coarsening of recrystallization occurring during a heat treatment such as a solution treatment performed thereafter, thereby bringing about finer recrystallization, thereby improving the appearance.

[Brief description of the drawings]

FIG. 1 is a processing diagram of a method for manufacturing a Mn-added aluminum alloy extruded material according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the amount of tensile processing of a 2219 alloy and the crystal grain size after solution treatment.

FIG. 3 is a diagram showing the relationship between the amount of tensile processing applied to a 2219 alloy before heat treatment and the appearance-appearing crank.

FIG. 4 is a schematic view showing a state of a surface roughened layer of a 2000-series extruded material according to a conventional manufacturing method.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 690 C22F 1/00 690

Claims (1)

[Claims] 1. A method for producing a Mn-added aluminum alloy extruded die, comprising subjecting a hot-extruded die of an Mn-added aluminum alloy to cold working and then performing a heat treatment.