JP2000271631A - Extruded material and method for producing molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extruded material having excellent mechanical properties, capable of being subjected to extrusion molding and cold working, to efficiently produce an extruded material and a molded product, and to have less molding defects and a method for producing the molded product. I will provide a. SOLUTION: The alloy material is subjected to plastic deformation (strain) corresponding to elongation of 220% or more, the average crystal grain size is reduced to 10 μm or less, and the average particle size of the intermetallic compound is reduced to 1 μm or less. Extrusion molding is performed in the solid state. One means of plastic deformation is to change the direction of extrusion of the alloy material to the side with an interior angle of less than 180 ° on the way to give shear deformation, and the other means is to change the pressure direction with respect to the alloy material to change the cross section. This is to change the shape and apply pressure deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruded material of an alloy and a method for producing a molded article using the extruded material.

[0002]

2. Description of the Related Art Generally, the ductility of a metal or an alloy becomes higher as the temperature becomes higher, which facilitates forming. However, when a metal or an alloy is exposed to a high temperature, there is a problem that its mechanical properties (strength, hardness, etc.) are reduced. On the other hand, the temperature at which the mechanical properties (strength, hardness, etc.) do not decrease
Deformability is as small as 100% or less, and it is difficult to form. Also, for example, in the case of a magnesium alloy, it is attracting attention as a material that can be expected to be further reduced in weight compared to an aluminum alloy, but has poor plastic workability, is difficult to extrude like an aluminum alloy, and is difficult to cold work. There is such a problem.

On the other hand, aluminum alloy is JIS A6
There are materials which can be extruded smoothly, such as the 063 alloy, and materials which are difficult to be extruded and cold worked such as 2000 series or 7000 series.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has excellent mechanical properties.
An object of the present invention is to provide an extruded material and a method for manufacturing an extruded material and a molded product, which can perform extrusion molding and cold working, efficiently produce an extruded material, and a molded product, and hardly cause molding defects.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an alloy material having two components.
Plastic deformation (strain) equivalent to elongation of 20% or more is given, the average crystal grain size is reduced to 10 μm or less, the average particle size of the intermetallic compound is reduced to 1 μm or less, and the obtained material is extruded in a solid state. And a method for producing an extruded material.

The alloy material applicable to the present invention is M
Magnesium alloys such as g-Al-Zn-based (AZ-based) alloys, Mg-Zn-Zr-based (ZK-based), Al-Mg-Si
200 (typically 6000 series) alloy, Al-Mg (5000 series) alloy, duralumin, super duralumin
0 system alloy, Al-Zn-Mg-Cu system, Al-Zn-M
Aluminum alloys such as 7000 series alloys represented by g series, zinc alloys, titanium alloys and the like can be applied, and particularly useful for Mg alloys and Al alloys. Further, Sc, Zr, Ti, Cr, M
It is preferable that at least one element of n, Si, and Ca is contained in a range of 5 wt% or less.

[0007] In the present invention, hot plastic working in advance is performed without causing plastic deformation and cracking at the time of forming in the next step, and the crystal grains and intermetallic compound of the alloy material are formed. It is also useful for miniaturizing the size of the alloy. Extrusion, forging, etc. can be applied as specific processing, and the specific processing temperature is 2 in the case of Mg alloy.
It is preferably performed at a temperature of from 00 to 360 ° C, and in the case of an Al alloy, from 350 to 500 ° C. In particular, it is important for a material produced by a casting method to destroy its casting structure. Further, when performing the hot plastic working, the solution treatment may be performed in advance at a temperature higher than the temperature of the extrusion, forging or the like.

Further, in the present invention, a large deformation with a strain amount corresponding to a considerable elongation of 220% or more is applied. As a specific method for these, first, the cross-sectional area of the alloy material is reduced. By changing the extrusion direction to the side with an inner angle of less than 180 ° in the middle without giving any change and applying a shear stress, a large strain corresponding to a considerable elongation of 220% or more is applied, and the average grain size of the microstructure is increased. Is 10 μm or less, the average particle diameter of the intermetallic compound is reduced to 1 μm or less is a method of the method of manufacturing an extruded material according to claim 1,
Second, the alloy material is subjected to pressure deformation by changing the pressure direction and changing the cross-sectional shape of the material, thereby applying a large strain corresponding to a considerable elongation of 220% or more, thereby obtaining an average crystal of microstructure. The particle size is reduced to 10 μm or less, and the average particle size of the intermetallic compound is reduced to 1 μm or less.
It is a technique of the manufacturing method of the extrusion-molded material described.

The method of the present invention will be described in detail.
First, the first method is a side extrusion method, which is most preferable in terms of productivity, economy, and the like. As shown in FIG. 1, the side extrusion method according to the present invention comprises two extruded containers having the same cross-sectional area on the inner surface, or a container 1 and a die 2 formed by 180.
Joining at an appropriate angle (2 °) of less than 1 °, inserting the alloy material S into one container 1 and extruding it towards the next container or die 2 by means of the ram 3, thereby laterally shearing the material. And preferably this step is performed a plurality of times. By applying this method to the alloy material, the crystal grains can be refined to 1 micron or less in a very simple process and without reducing the cross-sectional area, and can be strengthened more than the strength by conventional work hardening. At the same time, the toughness can be greatly improved. In addition, the process has the effect of destroying and homogenizing the casting structure, macro- and micro-segregation of alloy components, and omits the high-temperature and long-time homogenization heat treatment generally performed for alloy materials. You can also. Further, even if the cross section of the die 2 is reduced, the effect is not changed.

[0010] The amount of shear deformation applied to the alloy material by the side extrusion method of the present invention differs depending on the joining angle between the two containers or the container and the die. Generally, the amount of strain Δε _i per extrusion by such shear deformation is given by the following equation (1).

[0011]

(Equation 1)

(However, △ ε _i is the amount of strain, ψ is 1 of the internal joint angle.)
/ 2, ERR is the area ratio before and after processing, A ₀ is the cross-sectional area before processing, A is the cross-sectional area after processing, EAR is the equivalent cross-sectional reduction rate before and after processing, and EE is the equivalent strain (synonymous with elongation). That is, when the inner angle of the joint between the two containers or the container and the die is a right angle (90 °), the amount of strain is 1.15 (equivalent elongation: 220%) in one side extrusion, and when 120 °, the strain is The amount is given at 0.67 (equivalent elongation: 95%). By extruding at right angles to the side while keeping the same cross-sectional area, a process equivalent to a rolling reduction (cross-sectional reduction) of 69% by rolling can be added.

By repeating the above process, infinite strain can be accumulated in the material without changing the cross-sectional area of the material. The cumulative strain amount ε _t given to the material by the repetition is given by the following equation (5).

Ε _t = △ ε _i × N (5) (However, ε _t represents the integrated strain amount, and N represents the number of extrusions.) The number of repetitions (N) is theoretically preferably as large as possible. Actually, the effect is saturated in a certain number of times depending on the alloy. In a general wrought alloy material, a sufficient effect can be obtained when the number of repetitions is four (when the joining angle is a right angle, the integrated strain amount is 4.6 and the equivalent elongation is 10000%). Infinite strains can also be accumulated by rolling, in which case the cross-sectional area becomes infinitely small, in contrast to the lateral extrusion method.

The lateral extrusion according to the invention is preferably carried out at as low a temperature as possible. However, the deformation resistance of the alloy tends to be higher at lower temperatures, and the deformability tends to be lower at lower temperatures. In order to obtain the relationship between the strength of the extrusion tool and the sound extruded material, it is usually carried out at an appropriate temperature depending on the alloy. Generally, it is performed at a temperature of 300 ° C. or lower, preferably at a temperature lower than the recrystallization temperature of the alloy, more preferably at a temperature lower than the recovery temperature. However, the recrystallization temperature and the recovery temperature vary depending on the degree of processing applied to the material. The extrusion temperature varies depending on the extrusion angle, and the larger the angle, the lower the temperature. This is because the pushing force (energy required for the shearing deformation) is reduced and the constraint due to the deformability of the material is relaxed.

As shown in FIG. 2, the second method is a method of forging by successively changing the compression (pressing) direction. For example, the cross section is changed by pressing and compressing from both sides in the X-axis direction. A change is applied to the material, and then a compressive deformation is sequentially applied from both sides in the Y-axis direction, and further from both sides in the Z-axis direction. At this time, it is more preferable that the cross-sectional area of the material is not changed. Also in this method, a strain amount corresponding to a considerable elongation of 220% or more can be given as in the case of the above-mentioned side extrusion method, and the crystal grains and intermetallic compounds can be refined. The temperature at the time of forging can be applied in the same manner as the above-mentioned extrusion temperature.

According to these techniques, the average crystal grain size is 10
μm or less, and the average particle diameter of the intermetallic compound can be 1 μm or less.
0 ° C., can be molded into various shapes by molding condition strain rate ^{10 ~ 5 ~10 0 s ~ 1} . When molding, 150%
Due to the above elongation, the material is deformed by deformation due to grain boundary sliding and intragranular (plastic) deformation, and superplastic deformation occurs. In addition, due to the presence of the fine intermetallic compound, even if heating is performed as described above during molding, coarsening of crystal grains is suppressed, and a decrease in mechanical properties hardly occurs. In consideration of superplastic forming and mechanical properties, the average crystal grain size is preferably 3 μm or less, more preferably 1 μm or less.

In the present invention, the material having undergone the plastic deformation corresponding to the elongation of 220% or more is extruded in the solid state. It is less susceptible to mechanical influences, it is easier to maintain mechanical properties, and by extruding in the solid state, the residual gas in the container is less likely to be mixed into the extruded material, and the rear dummy block and die Degassing is performed more smoothly, and defects are less likely to occur in the extruded material. Further, the deformation due to the extrusion molding of the material becomes a superplastic deformation as described above, and the extruded material is formed from the die.

Hereinafter, a specific extrusion molding apparatus and an extrusion molding method will be described with reference to FIG.

The extruder is provided with a container 5 provided with a supply section 4 communicating in the longitudinal direction, and a die provided with one end of the supply section 4 and having an opening having a cross-sectional shape of the extruded material M to be formed. 6 and a stem 8 provided on the other end side of the supply unit 4 and provided with a dummy block 7 on one side sliding in the supply unit 4 toward the die 6. Although not shown, the extrusion molding apparatus is provided with a heating / cooling unit for controlling the temperature in the container, a temperature detecting unit, a temperature controlling unit, and the like. Extrusion is formed on the die 6 by arranging the extruded material S in the supply unit, sliding the stem 8 on the other end side toward the die 6, and pressing the extruded material S toward the die 6. An extruded material M having a sectional shape that matches the opening is produced. In this case, by reducing the cross-sectional area of the extruded material S by the die 6, the material is distorted, and the extruded material M can be further improved in mechanical properties. Specific extrusion molding conditions are temperature 100
To 450 ° C., it is preferably performed at a strain rate ^{10 ~ 5 ~10 0 s ~ 1} .

Further, extruded material obtained in this way, the temperature 500 ° C. or less, the liquid pressure-gas pressure blow molding under the condition of strain rate ^{10 ~ 2 ~10 0 s ~ 1} , press molding, spinning, bending , As well as plastic processing such as drawing
Diffusion bonding using superplastic flow can be performed under the same conditions.

According to the present invention, by performing such molding and processing, shapes and parts for automobiles, construction materials, etc.,
It can be used for a wide variety of applications such as home appliance frames.

[0023]

Now, the present invention will be described in detail with reference to Examples and Comparative Examples.

Example 1 A ZK60 alloy having a composition range shown in Table 1 was selected as an applicable alloy, and a round bar having a diameter of 80 mm was formed by casting. The obtained round bar was heat-treated at 499 ° C. for 2 hours, and then rapidly cooled in water. Thereafter, a round bar having a diameter of 25 mm was formed by hot extrusion (300 ° C., extrusion ratio 10) to obtain a test material. As a comparison material,
A hot extruded material (crystal grain size: 25 microns) of the above alloy and a cast material were used. This test material was inserted into one of two containers (both having a diameter of 25 mm) connected at a right angle (ψ = 45 °) and subjected to eight lateral extrusions at 180 ° C.
mm was obtained. Thus, according to the above equation, the integrated strain (ε _t ) is 9.4 (equivalent elongation of 1,000,000%).
This means that a magnesium alloy material that has been processed is obtained.

The structure of the material after the lateral extrusion at 180 ° C. was observed by a transmission electron microscope (TEM) image (magnification: 30,000 times). As a result, the crystal grains were reduced to about 0.5 μm after the lateral extrusion. It turned out that it was miniaturized.

From the laterally extruded material thus produced,
A tensile test piece having a parallel part length of 5 mm and a diameter of 2.5 mm was prepared at a constant temperature of 300 ° C., a strain rate of 1 × 10 to ³ and 1 × 10
It was ~ ^2, 1 × tensile 10 under the conditions of ~ ¹ s ~ ¹ test. FIG. 4 shows the results.

As is apparent from FIG. 4, the breaking elongation with a strain rate increases, next to the maximum 300% at ^{1 × 10 ~ 2 s ~ 1} , and decreased at higher. Thus, the breaking elongation 20
The high deformability of 0% or more is due to the fact that the microstructure is Zr.
This is because such precipitates are thermally stable and have intragranular plastic deformation and grain boundary slip.

An extrusion experiment was performed using the above materials. Extrusion temperature 300 ° C, extrusion ratio 50, extrusion speed 1mm / s
And

From these extruded materials, a parallel part length of 15 m
m, a parallel part width of 3 mm, and a parallel part thickness of 2 mm were prepared, and a tensile test was performed at room temperature and at a strain rate of 1 × 10 to ³ s- ¹ . Table 2 shows a comparison between the results and the extrusion surface pressure.

The extruded surface pressure is 500 M for an extruded material obtained by extruding a laterally extruded material of ZK60 alloy (hereinafter referred to as a laterally extruded material).
On the other hand, the hot-extruded material (crystal grain size: 25 microns) of the same alloy and an extruded material obtained by extruding a cast material (hereinafter, hot-extruded material, cast material) are close to 1000 MPa. The side extruded material had lower surface pressure.

The yield stress was 3 for the laterally extruded ZK60 alloy.
70 MPa, 300 MPa for a hot extruded material (crystal grain size: 25 microns) of the same alloy, 25 for a cast material
It was 0 MPa, and the laterally extruded material was superior.

From the above, it can be seen that the use of a material that has been miniaturized to about 0.5 μm allows a high-strength difficult-to-process material to be extruded at a low surface pressure. From this,
It can be seen that thinning and high extrusion speed are possible.

[0033]

[Table 1]

[0034]

[Table 2]

Example 2 Al-5Mg-0.5Sc-0.15Z as applicable alloy
r was selected and cast into a round bar having a diameter of 80 mm. The obtained round bar was heat-treated at 425 ° C. for 16 hours, quenched in water, and then hot-extruded (450 ° C., extrusion ratio 10) to form a round bar having a diameter of 25 mm. Bars were used as test materials. As comparative materials, a water-quenched material of the above alloy (crystal grain size: 25 μm) and a water-quenched material of a practical alloy A6063 alloy and A2024 alloy were used. This test material has a right angle (ψ = 45
°) connected to two containers (both 25m in diameter)
m) and subjected to four side extrusions at 100 ° C. to obtain a treated material having a diameter of 25 mm. Thus, according to the above equation, the integrated strain (ε _t ) is 4.6 (equivalent elongation of 100).
(00%).

The structure of the material after the lateral extrusion at 100 ° C. was observed by a transmission electron microscope (TEM) image (magnification: 30,000 times). As a result, the crystal grains were reduced to about 0.5 μm after the lateral extrusion. It turned out that it was miniaturized.

From the laterally extruded material thus produced,
A tensile test piece having a parallel part length of 5 mm and a diameter of 2.5 mm was prepared at a constant temperature of 400 ° C., a strain rate of 1 × 10 to ² and 1 × 10
Tensile tests were performed under the conditions of ~ ¹ and 1 × 10 ⁰ s ~ ¹ . The result is shown in FIG.

As apparent from FIG. 5, the elongation at break monotonically decreases with the strain rate. However, it shows a breaking elongation of 800% or more in the range of the measured strain rate. The high deformability of elongation at break of 200% or more is because the structure is thermally stable due to fine precipitates of Al ₃ Sc and Al ₃ Zr, and is accompanied by intragranular plastic deformation and grain boundary slip. It is.

Extrusion experiments were performed using the above materials. The extrusion temperature is 400 ° C, the extrusion ratio is 50, and the extrusion speed is 1 mm / s
And

From these extruded materials, the parallel part length was 15 m.
m, a parallel part width of 3 mm, and a parallel part thickness of 2 mm were prepared, and a tensile test was performed at room temperature and at a strain rate of 1 × 10 to ³ s- ¹ . Table 3 shows a comparison between the results and the extrusion surface pressure.

Al-5Mg-0.5Sc-0.15Zr
An extruded material (hereinafter referred to as a water-quenched material) obtained by extrusion-molding a water-quenched material of A2024 alloy had a surface pressure of about 1000 MPa. Al-5Mg-0.5Sc-0.15Zr
The surface pressure of the extruded material (hereinafter referred to as “side extruded material”) obtained by extruding the side extruded material was higher than the water-quenched material of the A6069 alloy, but lower than the water-quenched material of the same alloy.

The yield stress is Al-5Mg-0.5Sc-
While the side extruded material of 0.15Zr is 400MPa, the water quenched material of the A6063 alloy having a low extruded surface pressure is 150MPa, and the Al-5Mg-0.5S having a high extruded surface pressure is 150MPa.
c-0.15Zr and water hardened material of A2024 alloy are 2
It is 00 to 350 MPa, and the laterally extruded material is superior.

From the above, it can be seen that the use of a material which has been miniaturized to about 0.5 μm allows a high-strength difficult-to-process material to be extruded at a low surface pressure. From this,
It can be seen that thinning and high extrusion speed are possible.

[0044]

[Table 3]

[0045]

According to the present invention, it is possible to obtain an extruded material and a molded product, which are excellent in mechanical properties, can be subjected to extrusion molding and cold working, and are efficiently and less likely to have molding defects.
It can be used for a wide variety of applications such as shapes and parts for automobiles and building materials, and frames for home appliances.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method of giving plastic deformation to an alloy material in the present invention.

FIG. 2 is an explanatory view of another method of giving plastic deformation to an alloy material in the present invention.

FIG. 3 is an explanatory view of an apparatus for extruding an alloy material in the present invention.

FIG. 4 is a graph showing a tensile test result of a laterally extruded material according to Example 1.

FIG. 5 is a graph showing the results of a tensile test of a laterally extruded material according to Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Die 3 Ram S alloy material 4 Supply part 5 Container 6 Die 7 Dummy block 8 Stem M Extruded material

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) C22F 1/00 612 C22F 1/00 612 630 630K 631 631A 694 694B 694A (72) Inventor Junichi Nagato Sendai, Miyagi (12) Inventor Christian Pitan 4-24-5 Takanomori, Tomiya-cho, Kurokawa-gun, Miyagi Prefecture (72) Inventor Kenji Higashi 3-4-9 Teraikedai, Tondabayashi-shi, Osaka F-term (Reference) 4E029 AA06 AA07 4E087 AA10 BA03 BA04 BA24 CA21 CA22 CA27 CB01 CB03 CB04 CB11 CB12 DB12 DB15 DB23 EC01 EC11 EC17 EC37 EC46 EC54 GA02 GA07

Claims (8)

[Claims] 1. A material obtained by subjecting an alloy material to plastic deformation (strain) equivalent to elongation of 220% or more, and reducing the average crystal grain size to 10 μm or less and the average particle size of the intermetallic compound to 1 μm or less. Extruded in a solid state. 2. The method according to claim 1, wherein the alloy material is obtained by subjecting a cast material to hot plastic working. 3. The alloy material is extruded in the direction of the middle with an inner angle of 1 mm.
The method for producing an extruded material according to claim 1, wherein a large strain corresponding to an elongation of 220% or more is given by applying a shearing deformation by changing the side to less than 80 ° to refine the microstructure. 4. A large strain corresponding to elongation of 220% or more is given to the alloy material by applying pressure deformation by changing the pressure direction and changing the cross-sectional shape of the material to change the microstructure. The method for producing an extruded material according to claim 1, wherein the extruded material is miniaturized. 5. The method for producing an extruded material according to claim 1, wherein the extruded material is formed by giving a strain during the extrusion. 6. The method of claim 1 extruded material according performing extrusion temperature 100 to 450 ° C., in the molding conditions of strain rate ^{10 ~ 5 ~10 0 s ~ 1} . 7. A method for producing a molded product, wherein the extruded material obtained according to claim 1 is further subjected to plastic working and / or joining. 8. A plastic working and / or temperature remains 500 ° C. of solid state bonding following process according to claim 7, wherein under the condition of strain rate ^{10 ~ 2 ~10 0 s ~ 1} .