JPH04187747A - Manufacture of thick heat treatable aluminum alloy member having complicated shape - Google Patents

Abstract

PURPOSE:To improve the strength and toughness of an alloy member without the generation of buckling and cracking by subjecting the cast material of a heat treatable Al alloy to plastic working to obtain intermediate stock, subjecting it to soln. treatment, thereafter inserting a dummy block into the penetrating part or the like of the stock and executing cold compression. CONSTITUTION:The cast material of a heat treatable Al alloy is subjected to plastic working and machining to form intermediate stock contg. a projecting part, a penetrating part and a through-hole part. The intermediate stock is subjected to soln. treatment, and after that, a dummy block made of metal having 70 to 200% deformation resistance to the intermediate stock is inserted into the penetrating part and through-hole part of the intermediate stock. In this state, cold compression at least in the two-axis direction is executed to remove residual stress caused by the soln. treatment. As for the cold compression, the one to attain 1.5 to 5.0% compressive strain is executed in a one direction, and next, the one to attain 1.5 to 5.0% compressive strain is executed in the other direction orthogonally crossed with the above direction. After that, aging treatment is executed. In this way, a thick Al alloy member with a complicated shape excellent in strength and toughness can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is directed to a thick-walled and complex-shaped aluminum alloy having a specific shape including protrusions, recesses, and/or through-holes, made of a heat-treated aluminum alloy. The present invention relates to a method for manufacturing a heat-treated aluminum alloy member that is applied to manufacturing a light alloy member.

[Prior Art] As a heat-treatable aluminum alloy, for example, A
ff-Cu-Mg system (JIS 2000 system), A
Q -Mg-5i series (JIS 6000 series), Al-
Examples include Zn-Mg series (JIS 7000 series).

Conventionally, when manufacturing a heat-treated aluminum alloy member having a complicated shape, a cast material made of the above-mentioned heat-treated aluminum alloy is formed into a rectangular intermediate material by forging, and then the rectangular intermediate material is Solution treatment is performed L7, and then, in order to remove residual stress after the solution treatment, the rectangular intermediate material is treated in one direction,
For example, after performing cold compression in the thickness direction, aging treatment is performed, and then cutting is performed on the intermediate material after the aging treatment to remove specific shaped parts such as protrusions, invaginations, or through holes. An aluminum alloy member with a complicated shape has been obtained.

[Problems to be Solved by the Invention] However, in such a conventional method for manufacturing heat-treated aluminum alloy members, the rectangular intermediate material formed by forging has invaginations and surplus parts that are later removed. It is molded into a thick block shape that also includes the meat part,
Since the solution treatment is performed in this state, the thickness of the rectangular intermediate material becomes considerably large during the solution treatment, and the effect of the solution treatment is not sufficient and it is difficult to obtain a product with high strength and high toughness. Have difficulty. In addition, if the residual stress generated during solution treatment is not sufficiently removed from this alloy, it will not only cause distortion and cracking during cutting, but will also promote stress corrosion cracking when exposed to sea breeze or seawater. Become. Conventionally, the residual stress has been removed by subjecting a rectangular intermediate material to uniaxial cold compression after solution treatment.

However, as mentioned above, with this method, for example, in the case of 7075 alloy, sufficient strength and toughness cannot be ensured when the thickness becomes about 100 mm.
- It is difficult to remove residual stress sufficiently by compressing only the axis.
New methods need to be developed. One method is to solutionize an intermediate or finished material with a specific shape such as a protrusion, recess, or through hole, immerse it in liquid nitrogen at -196°C instead of compression, and then heat it with steam. , an "uphill quench method" was developed that provides a thermal cycle opposite to that of solution cooling at the surface and inside the plate. However, this method not only requires the cost of the refrigerant, but also requires extremely complicated equipment such as the need to arrange the steam nozzle to match the shape, making control difficult, and furthermore, the residual stress removal effect is not sufficient. For this reason, it has not yet become widespread.

Therefore, the inventors of the present application first filed the patent application No. 1-179724.
+: After forming an intermediate material having specific shaped parts such as protrusions, invaginations, or through holes from a cast material made of heat-treated aluminum alloy, and subjecting this intermediate material to solution treatment. After the solution treatment, the intermediate material is subjected to cold compression in one direction with a compressive strain of 1.5 to 5.0%, and further cold compressed with a compressive strain of 1.5 to 5.0%. We have proposed a method for manufacturing a heat-treated aluminum alloy member, characterized in that cold compression is performed in at least two axial directions, in which compression is performed in another direction perpendicular to the one direction, and then an aging treatment is performed. According to this method, sufficient strength and toughness can be ensured, and residual stress can be sufficiently removed. However, [7] As a result of further investigation, it was found that in the case where there is a partially thin walled portion, there is a possibility that buckling or cracking may occur during compression using the above method.

The present invention has been made in view of these circumstances, and improves strength and strength by increasing the heat treatment effect of solution treatment and making sufficient the effect of removing residual stress generated by solution treatment. An object of the present invention is to provide a method for manufacturing a heat-treated aluminum alloy member that can improve toughness without causing cracking or buckling.

[Means for Solving the Problems] The method for manufacturing a thick-walled, complex-shaped heat-treated aluminum alloy member according to the present invention involves performing plastic working and cutting on a cast material made of a heat-treated aluminum alloy. Or by performing only plastic working, protrusions,
An intermediate material having a specific shape including an invaginated portion and/or a through hole is formed, and then the intermediate material is subjected to solution treatment, and then 70% or more of the intermediate material after the solution treatment is 200% A metal dummy block having a deformation resistance of 1.5 to 5% is inserted into the recess and through hole, and the compressive strain of the intermediate material is set to 1.5 to 5%.
Cold compression is performed in one direction so that the compression strain becomes 0%, and the compression strain becomes 1.
It is characterized by performing cold compression in at least two axial directions in which cold compression to 5 to 5.0% is performed in another direction orthogonal to the one direction, and then subjecting it to aging treatment.

Hereinafter, a method for manufacturing a heat-treated aluminum alloy member according to the present invention will be described in detail.

As mentioned above, examples of the heat-treatable aluminum alloy used in the present invention include JIS201.4, 20
There are 2000 series represented by 17.2024, 6000 series represented by 606], 7000 series represented by 7NO1, 7075, etc., and it goes without saying that these are not limited to those established by JIS. , Fe, Sn
.

Elements such as V, Cr, and Mo are appropriately added, or the above-mentioned alloys are used in which the amounts of these added elements are increased or decreased.

When manufacturing an aluminum member made of such a heat-treated aluminum alloy according to the present invention, first, a cast material made of the heat-treated aluminum alloy is subjected to plastic working such as forging, or By using such plastic working and cutting in combination, an intermediate material 1 as illustrated in FIG. 1 is formed. This intermediate material 1 has four protrusions and 2811 invaginations 2.
It is thick and has a complicated shape, having a through hole portion 2C at two locations as specific shaped portions.

Note that the specific shaped part here refers to processed parts such as protrusions, invaginations, and through holes, but is not necessarily limited to these and may include other shaped parts. . Moreover, it is not necessary that all of the protruding part, the recessed part, and the through-hole part exist as such a specific shaped part, and only the recessed part or the through-hole part may be present.

Next, the above-mentioned intermediate material 1 is subjected to solution treatment. This solution treatment is carried out under the following conditions: for example, 2024-T62 material is heated to 490-500°C, solution-treated, and then water-cooled, and 6061-762 material is heated to 515-550°C, solution-treated, and then water-cooled. , 7075-T62 material is heated to 460 to 500°C to form a solution, and then cooled with water.

Next, metal dummy blocks having a deformation resistance of 70% or more and 200% or less of the deformation resistance of the intermediate material 1 are inserted into the invaginations and through holes of the intermediate material 1 after the solution treatment, and the remaining In order to remove stress, cold compression is performed in at least two axial directions under predetermined conditions. This cold compression is performed at least in one direction with a compression strain of 1.5 to 5.0%, and then cold compression with a compression strain of 1.5 to 5.0% in one direction. This is carried out in another direction orthogonal to the direction, and in this case, the two axial directions can be selected, for example, as shown in FIG. 1 and the X direction. Note that the order and direction during cold compression are not particularly limited, and it is sufficient to select at least two axial directions that are easy to process among the three mutually orthogonal axes, and if necessary, the cold compression may be repeated three or more times. good.

In the present invention, the intermediate material 1 after solution treatment is cold compressed in at least two axial directions.
This is because there are regions where the residual stress removal effect due to cold compression cannot be expected only in one axial direction due to the complicated shape of the material. The reduction in residual stress when cold compressed in two axial directions will be explained with reference to FIGS. 6, 7, and 8.

FIG. 6 partially shows an infinite flat plate 20 with a thickness of 40 mm, in which Z indicates the compression direction, Y indicates the thickness direction, and X indicates the direction of the plate surface perpendicular to these two directions. .

Fig. 7 shows the flat plate 20 shown in Fig. 6 after being subjected to solution treatment by heating to 470°C and water quenching in 20°C water, and then compressed in two directions (under external force load). This shows the results of calculating the change in internal stress with respect to compressive strain by thermal stress analysis, where the internal stress in the compression direction (two directions) is σ8, the internal stress in the thickness direction (X direction) is σ2,
The internal stress in the plate surface direction (X direction) is indicated by σ8.

As is clear from Fig. 7, the internal stress σ2 in two directions is
When the compressive strain is 1.5% or more, the stress level is the same on the surface and the center, and the internal stress σ in the X direction and the internal stress σ in the X direction converge to O when the compressive strain is 1.5% or more. . Note that this analysis result is based on an infinite flat plate 2 with a thickness of 40 mm.
0, the internal stress σ in the X direction is 0 even after solution treatment, but in the case of an actual flat plate with finite (predetermined) dimensions, There is also an internal stress σ in the direction. Therefore, the stress distribution in the plate thickness direction (X direction) and the plate surface direction (X direction) perpendicular to the compression direction (Z direction) converges to 0 when the compressive strain is 1.5% or more. After this cold compression from the Z direction, the internal stress (σ8.7 .σK) converges toward O when the compressive strain σ is 1.5% or more.

Conversely, in uniaxial compression, the internal stress (σ,

σ7. It will be difficult to make all σ, ) close to zero.

Figure 8 shows the residual stress distribution after the cold compression force in the Z direction is released from the state shown in Figure 7, which shows changes in internal stress due to compressive strain when cold compression is performed in the Z direction. . If the cold compression force is released or the final residual stress state is achieved, for example, if the compressive strain or cold compression is 2.09°,
As shown in FIG. 8, the residual stress becomes extremely small.

As described above, in the present invention, the compressive strain during cold compression is specified to be at least 1.5%, which allows the internal stress force to converge toward the internal stress (01), as described above.

However, if the compressive strain is too large, the load on the intermediate material 1 will be excessive, so it is specified to be 50% or less.

Regarding the dummy block, if its deformation resistance is less than 70% of the intermediate material after solution treatment, the dummy block will easily deform and will no longer be used as a restraining body to prevent buckling or cracking. As expected, if the reverse 1 is larger than 200%, the compressive deformation of the intermediate material will not progress in the part where it touches the dummy pro, and the residual stress removal force cannot be achieved.Also, the same as with the intermediate material. Metal is desirable as a material that can be deformed to It is desirable to apply a lubricant such as No. 32 to prevent galling and ensure smooth deformation.Also, the shape of the dummy block is approximately the same as the invaginated part of the intermediate material and the clearance of 0.3 degrees or less. It should have the same size and shape as the through hole.If the specific shaped part has an invaginated part and a through hole, the dummy prong should be inserted into both of these parts.

Next, the cold-compressed intermediate material 1 is subjected to an aging treatment, and then, if necessary, the surface of the intermediate material 1 is subjected to finishing processing such as cutting or polishing to finish it to predetermined dimensions. , protrusion 2 a s invagination 2 b,
A heat-treated aluminum alloy member having specific shaped portions 2 such as through-hole portions 2C is obtained. Note that the aging treatment is performed, for example, in the case of 2024-T62 material at a temperature of 185 to 19
Approximately 9 hours at 5℃, 155 for 6061-T62 material
The heating can be carried out at ~165°C for about 18 hours, and in the case of 7075-T62 material, at 115~25°C for about 24 hours or more.

For reference, the degree of residual stress removal by the above-mentioned "uphill quench method" and compression method is shown in FIG. After quenching, the stress difference between the center of wall thickness and the surface layer is 50 kg f.
/w 2, whereas after aging it was 15 kgf/mm2 with uphill quenching and 5 kgf/am2 with compression, indicating that the compression method is superior as a residual stress removal method. I understand that.

[Operation] In the present invention, the cast material is processed by performing plastic working such as forging on the cast material before solution treatment, or by using a combination of plastic working such as forging and cutting. An intermediate material having a specific shape including protrusions, invaginations, and/or through holes is formed to approximate the shape of the final product, and then the intermediate material is subjected to solution treatment, followed by cold compression. Since the process is carried out in at least two axial directions, the thickness of the intermediate material becomes thinner during the solution treatment, so that the heat treatment effect of the solution treatment is sufficient, and the residual stress generated by the solution treatment is reduced. The removal effect is sufficient. Therefore, it is possible to obtain a heat-treated aluminum alloy member with high strength and high toughness. Furthermore, since dummy blocks having a specific range of deformation resistance are inserted into the invaginations and through-holes of the intermediate material during compression, buckling and cracking do not occur even in thin-walled parts.

[Example] As shown in FIG. 2, three invaginations 4a,
4b, 4c and one through hole 4d are formed into a specific shape part 4.
As provided, length: -680 mm, width: W2-660
An intermediate material 3 with a height of H2-285 mm was created.

Next, as shown in FIG.
Solution treatment was performed under conditions of heating to 68°C, holding for 6 hours, and then cooling with water.

Next, dummy blocks with various deformation resistances or different clearances of 0.3 or less are placed in the invaginations and through-holes.
After inserting the intermediate material 3 coated with S2, the solution-treated intermediate material 3 was cold compressed in two axial directions in order to remove residual stress in the intermediate material 3 after the solution treatment. For comparison, cold compression was also carried out without inserting gummy blocks, and cold compression in the axial direction was also tested. Various test conditions at this time are shown in Table 1.

Test numbers] to 3 in Table 1 are examples within the scope of the present invention, and test numbers 4 to 9 are comparative examples outside the scope. As for test number 4, as will be described later, a conventional method was used in which an intermediate material was used that did not form a specific shape part, and the specific shape part was formed in a subsequent process.

At this time, the biaxial cold compression is performed using the 7075 shown in Fig. 5.
The test was carried out as shown below in accordance with the relationship between the compressive load and the compressive strain of the material, that is, the relationship expressed by the following equation (1) in the straight line section of FIG.

Fヰ[24,9+ 3.8 δIXS・・・・・・
... (1) [Tatashi, F is press load (kgf), δ
is compressive strain (%), S is press cross-sectional area (m12), and the constant unit is kgf/m! It is 12. ] That is, the intermediate material 3 after the solution treatment was first subjected to cold compression in the Z direction in FIG. 2 with a compressive load of about 67 tons except for some samples, resulting in a reduction of about 2.5%. Then, as shown in Figure 2, cold compression in the Y direction was applied with a compressive load of about 67 tons, resulting in a compressive strain of about 2.5%. Cold compression was performed in two axial directions, the Z direction and the Y direction, so that the following properties were applied. For test number 9, uniaxial compression was performed only in the Z direction.

Next, as shown in FIG. 3, the intermediate material 3 after the cold compression was heated at 108°C for 7 hours and at 65°C.
After performing a two-stage aging treatment for 7 hours, a finishing process (cutting process) is performed to obtain a heat-treated aluminum alloy member having a specific shape part 4 consisting of invaginations 4a, 4b, 4c and a through hole part 4d. Obtained.

Moreover, the test number 40 member was formed as follows.

That is, first, a cast material made of J 157075 material, which is a heat-treated aluminum alloy, is forged as in the above embodiment, and as shown in FIG. 4, the length L4-
680mm, width W4-660mm.

A rectangular block-shaped intermediate material 10 with a height of H4-3101111 was created.

Subsequently, the block-shaped intermediate material [0] was subjected to solution treatment under the conditions of heating to 468° C., holding for 6 hours, and cooling with water, as shown in FIG. 3, as in the above-mentioned example.

Next, the block-shaped intermediate assembly 10 after the solution treatment is cold compressed only in the Z direction in FIG.
A compressive strain of about 2.5% was applied by applying a compressive load of 1,000 tons.

Next, as in the above embodiment, as shown in FIG. 3, a two-stage aging treatment of 108° C. x 7 hours and 165° C. x 7 hours is performed, and then the block-shaped intermediate material 10 is subjected to cutting processing. Accordingly, the recessed portions (4a, 4b, 4c) having the same shape and the same dimensions as the embodiment shown in FIG.
A heat-treated aluminum alloy member having a specific shape portion 4 consisting of a through hole portion (4d) and a protrusion portion (4e) was obtained.

Then, the surface residual stress of each aluminum alloy final finished member obtained in this way (center of the back surface, protrusion 4
The height and width center of e), tensile properties, and fracture toughness were evaluated.

These results are shown in Table 1. The residual stress was determined by the drilling method (ASTM E83) at the center position on the back side of the surface layer in Figure 2 or Figure 4, and at the height and width center of the protrusion 4e.
7), and the mechanical properties were measured at the center of the height and center of the thickness of the protrusion sandwiched between the invaginations 4a and 4b.

As is clear from the results shown in Table 1, in the cases of test numbers 1 to 3 of the examples of the present invention, no buckling or cracking occurred, and almost all residual stress was removed after the two-step aging treatment. , yield strength (YS), tensile strength (TS), and fracture toughness (KIc) were also obtained, indicating that the effects of the present invention were sufficiently obtained.

On the other hand, test number 1, which was hardened in a rectangular parallelepiped shape, was inferior in strength and toughness, and if a dummy block was not inserted, or if the deformation resistance was too low even if a dummy block was inserted, as in test numbers 5 and 7, It was confirmed that buckling and cracking occurred in thin-walled parts.

In addition, if the amount of compressive strain is small as in test numbers 6 and 8, or if the deformation resistance of the dummy block is too high, sufficient residual stress removal effect cannot be obtained. It was confirmed that residual stress cannot be effectively removed by compression alone.

[Effects of the Invention] As explained above, according to the method for manufacturing a heat-treated aluminum alloy member according to the present invention, the wall thickness during solution treatment can be reduced, so that the heat treatment effect due to solution treatment can be reduced. It can be made sufficient. Further, since residual stress can be sufficiently removed without buckling or cracking during compression, it is possible to obtain a heat-treated aluminum alloy member with excellent strength and toughness.

Furthermore, by being able to reduce the residual stress of the aluminum alloy member in this way, it is also possible to improve the stress corrosion cracking resistance.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of an intermediate material before heat treatment used in the method for manufacturing a heat-treated aluminum alloy member according to the present invention, and FIG. 2 shows the shape of the intermediate material before heat treatment used in an example of the present invention. FIG. 3 is an explanatory diagram showing the heat treatment conditions applied in the examples and comparative examples of the present invention, and FIG.
The figure is a perspective view showing the shape of the intermediate material before heat treatment used in the comparative example, Figure 5 is a graph illustrating the results of investigating the relationship between compressive load and compressive strain in 7075 material, and Figure 6 is a biaxial direction. A perspective view showing an infinite flat plate to explain the cold compression of
Fig. 7 is a graph illustrating the relationship between stress and compressive strain when cold compressed in biaxial directions, Fig. 8 is a graph illustrating the residual stress distribution after releasing cold compressive stress, and Fig. 9 2 is a diagram illustrating a comparison of the degree of residual stress removal between the "uphill quench method" and the compression method. 1.3...Intermediate material, 2,4...Specific shape part, 2a
. 4 e-...Protrusion, 2 b, 4 a, 4 c-
Invagination, 2c. 4d...Through hole section. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Q1234 Pressure distortion ('/,) 5th factor 0.5 1 15225 33.54 h gal r1 (0 m) Figure 7 Figure 8

Claims (1)

[Claims] (1) When manufacturing heat-treatable aluminum alloy members with thick walls and complex shapes that have specific shapes including protrusions, invaginations, and/or through-holes, plastic processing is performed on cast materials made of heat-treatable aluminum alloys. An intermediate material having a specific shape including a protrusion, an invagination and/or a through hole is formed by cutting or only by plastic working, and then the intermediate material is subjected to solution treatment. After that, a metal dummy block having a deformation resistance of 70% or more and 200% or less is inserted into the recessed part and through-hole part of the intermediate material after the solution treatment, and then The compression strain is 1.
At least two axial directions in which cold compression with a compression strain of 5 to 5.0% is performed in one direction and cold compression with a compressive strain of 1.5 to 5.0% is performed in another direction orthogonal to the one direction. A method for manufacturing a heat-treated aluminum alloy member having a thick wall and a complex shape, the method comprising performing cold compression and then subjecting it to an aging treatment.