JP2001140048A - METHOD OF MANUFACTURE FOR Al-Mg-Si TYPE ALUMINUM ALLOY EXTRUDED MATERIAL, AND METHOD OF WORKING - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an Al-Mg-Si type aluminum alloy extruded material to which a prescribed proof stress value is given by aging treatment by regulating the plastic strain of an extruded material to a predetermined value. SOLUTION: An Al-Mg-Si type aluminum alloy is extruded. Then, >=0.2% plastic strain is applied to the resultant extruded material by plastic deformation such as straightening, followed by aging treatment. As the Al-Mg-Si type aluminum alloy, an aluminum alloy containing 0.25-0.9% Si, 0.4-1.2% Mg, 0.1-0.3% Fe, 0.005-0.2% Ti and 0.001-0.01% B and further containing, if necessary, one or more kinds among 0.01-0.4% Cu, 0.05-0.2% Cr, 0.05-0.2% Zr and 0.05-0.3% Mn is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an extruded Al-Mg-Si-based aluminum alloy material having no variation in proof stress and suitable for bending.

[0002]

BACKGROUND OF THE INVENTION Al-Mg-Si based aluminum alloy, after forming into a predetermined shape by extrusion, high strength is given by the aging treatment for precipitating an intermetallic compound such as Mg ₂ Si. Taking advantage of this advantage, it is used in a wide range of fields, such as vehicle equipment, construction materials, and work equipment, in addition to being lightweight and excellent in corrosion resistance. To manufacture an Al—Mg—Si based aluminum alloy extruded material, it is cooled to around room temperature by air cooling, water cooling, or the like after extrusion processing, and then realigned.
A T5 treatment of aging at ~ 220 ° C, a solution treatment and a quenching prior to the aging treatment, and a method of adjusting after quenching T6 are adopted. Aged Mg-S
The proof stress value of the i-based aluminum alloy changes according to the alloy composition, the manufacturing history, the amount of the precipitate, and the like. Therefore, the alloy composition, homogenization conditions before extrusion, extrusion conditions (billet temperature, extruded material temperature, extruded material cooling rate, etc.), and aging conditions (holding temperature, holding time, etc.) are made as constant as possible. , The proof stress value was stabilized.

[0003]

Even if the alloy composition, homogenization conditions, extrusion conditions, and aging conditions are kept constant, the proof stress of the extruded material may still vary. When the cause of the variation in the proof stress value was investigated, even in the case of the extruded material manufactured in the same manner, the amount of precipitation of Mg ₂ Si and the like fluctuated, and the greater the amount of precipitation, the higher the proof stress value was. . The variation in the amount of precipitation is due to the fact that the degree of bending or length of the extruded material immediately after extrusion or after quenching differs for each extruded material, and the amount of plastic strain differs for each extruded material even if the same setting is used for realignment. It is inferred. If the amount of plastic strain is different,
During the aging treatment, the amount of dislocations serving as precipitation nuclei varies, and as a result, the amount of precipitation of Mg ₂ Si or the like that contributes to mechanical strength fluctuates.

In order to ship a product satisfying the required characteristics in consideration of the variation in proof stress, the amount of precipitation of Mg ₂ Si or the like is slightly larger in view of the fluctuation range, in other words, the proof stress higher than the target value. A method of performing aging treatment under the condition of imparting is given. However, recently, it has been required to guarantee not only the lower limit but also the upper limit of the proof stress value. For example, for extruded materials used for bending, it is necessary for the stability of the shape of the bent product to have a constant springback during bending, so it is necessary for users to keep the proof stress of the extruded material within a certain range. It has been demanded. In addition, in applications such as space frames for vehicles, it is necessary to protect the occupant by breaking when a force exceeding the threshold is applied and absorbing the impact. In this regard, the strength of the extruded material is kept within a certain range. Is required. At present, the demands on the range of proof stress values are becoming stricter, and Mg ₂ Si
The conventional aging treatment, which causes a relatively large amount of precipitation, cannot be used.

[0005]

SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem, and is intended to reduce the amount of precipitation of Mg ₂ Si or the like by keeping the plastic strain constant. It is another object of the present invention to provide an Al-Mg-Si-based aluminum alloy extruded material to which a certain proof stress is given by aging treatment. The production method of the present invention is characterized in that in order to achieve the object, after extruding an Al-Mg-Si-based aluminum alloy, a plastic strain of 0.2% or more is given by plastic deformation, and then aging treatment is performed. And
The plastic strain of 0.2% or more is given, for example, by straightening after extrusion.

[0006] As an Al-Mg-Si-based aluminum alloy, Si: 0.2-0.9% by weight, Mg: 0.4-
1.2% by weight, Fe: 0.1 to 0.3% by weight, Ti:
0.005 to 0.2% by weight, B: 0.001 to 0.01
% By weight, and further, if necessary, Cu: 0.01-0.
4% by weight, Cr: 0.05 to 0.2% by weight, Zr: 0.
An aluminum alloy containing one or more of 0.05 to 0.2% by weight and Mn: 0.05 to 0.3% by weight is used.

Specifically, an Al-Mg-Si-based aluminum alloy is extruded so that the material temperature immediately after exiting the extrusion die is 500 to 560 ° C, and the temperature range of 450 to 250 ° C is increased to 50 ° C / min or more. After cooling at 0.2%
The above plastic strain is given, and then aging treatment is performed. As the aging treatment, a T5 treatment in which the rectified Al-Mg-Si-based aluminum alloy extruded material is kept at 160 to 220 ° C, a T6 treatment in which solution treatment and quenching are performed prior to the aging treatment, and the like are employed. In the case of T6 treatment, plastic strain is imparted after quenching. In addition, T5 combined with die edge quenching
Processing can also be employed.

[0008]

[Action] On the premise that the cause of the variation in the proof stress is the amount of plastic strain of the extruded material, a method of making the plastic strain constant was studied. By changing the set value of the straightening machine for each extruded material and reshaping the extruded material with a tensile force according to the degree of bending and length of the extruded material, the plastic strain can be kept constant. However, it is not realistic to change the set value for each extruded material. Then, the present inventors investigated and examined the relationship between the amount of plastic strain applied to the extruded material by straightening and the proof stress value. As a result, the proof stress value increases as the amount of plastic strain increases at the initial stage as shown in FIG.
It has been found that the rate of change is small in a state where the above (preferably 0.4% or more) plastic strain is given.

It is presumed that the decrease in the rate of change is due to the fact that a large number of dislocations are generated when the amount of plastic strain is 0.2% or more, and the dislocations acting as precipitation nuclei during aging cancel each other out. Therefore, when a plastic strain of 0.2% or more is applied, even if the plastic strain is slightly different, the strength applied by the aging treatment does not fluctuate greatly, and it is not necessary to change the set value of the straightening machine for each extruded material. . However, excessive plastic strain reduces elongation of the extruded material and deteriorates the wall thickness and cross-sectional shape. Therefore, the amount of plastic strain applied to the extruded material is preferably set to 2% or less.

Next, the Al-Mg-
The alloy components, content, manufacturing conditions, and the like of the Si-based aluminum alloy will be described. Alloy component Si: 0.2 to 0.9% by weight An alloy component that precipitates as Mg ₂ Si during aging treatment and imparts strength to the extruded material. In order to obtain sufficient mechanical strength, a Si content of 0.2% by weight or more is required. However, when excess Si exceeding 0.9% by weight is contained,
Extruded material is liable to Mg ₂ Si precipitation in the process of being cooled immediately after extrusion, effective Mg ₂ Si in improving the strength at the time of aging treatment
The amount of precipitation decreases. Mg: 0.4 to 1.2% by weight An alloy component that precipitates as Mg ₂ Si during aging treatment and imparts strength to the extruded material. To obtain sufficient mechanical strength, a Mg content of 0.4% by weight or more is required. However, if an excess of more than 1.2% by weight of Mg is contained,
Extruded material is liable to Mg ₂ Si precipitation in the process of being cooled immediately after extrusion, effective Mg ₂ Si in improving the strength at the time of aging treatment
The amount of precipitation decreases.

Fe: 0.1 to 0.3% by weight An Al-Fe-Si alloy component that produces an Al-Fe-Si phase and refines the crystal grains of the extruded material to improve mechanical properties.
Such an effect becomes remarkable at 0.1% by weight or more. However, when an excessive amount of Fe exceeding 0.3% by weight is contained, although the Al—Fe—Si phase is increased in quantity, Si is reduced by that amount, and Mg ₂ Si precipitated during aging treatment is reduced.
Is reduced. Ti: 0.005 to 0.2% by weight This is an alloy component that has the effect of refining the crystal grains of the ingot and suppressing casting cracks. At 0.005% by weight or more, the effect of adding Ti becomes remarkable. However, an excessive amount of Ti exceeding 0.2% by weight promotes the formation of coarse Al-Ti crystallized substances and deteriorates extrudability.

B: 0.001 to 0.01% by weight An alloy component which has the effect of refining the crystal grains of the ingot and suppressing casting cracks, and the effect of adding B is remarkable at 0.001% by weight or more. Become. However, an excessive B content exceeding 0.01% by weight increases the Ti-B compound and deteriorates the extrudability. Cu: 0.01 to 0.4% by weight Alloy component added as necessary, 0.1% by weight
As described above, the effect of improving the mechanical strength becomes remarkable. However, when an excessive amount of Cu exceeding 0.4% by weight is added,
Mg ₂ Si tends to precipitate in the process of cooling the extruded material immediately after extrusion. As a result, Mg ₂ Si which does not contribute to the improvement of the mechanical strength under the cooling conditions specified in the present invention is precipitated, and the amount of Mg ₂ Si which is effective for improving the strength during the aging treatment is reduced.

Cr: 0.05 to 0.2% by weight Zr: 0.05 to 0.2% by weight Mn: 0.05 to 0.3% by weight Cr, Zr and Mn are added as required. An alloy component, which precipitates as a compound when the billet is homogenized before extrusion, exhibits an action of suppressing recrystallization of the structure and coarsening of recrystallized grains during extrusion, and prevents softening of the extruded material. It is also effective in improving corrosion resistance. Such effects become remarkable at 0.05% by weight or more for Cr and Zr and 0.05% by weight or more for Mn. However, when an excessive amount of Cr or Zr exceeding 0.2% by weight or an excessive amount of Mn exceeding 0.3% by weight is added, Mg ₂ Si tends to precipitate in a process of cooling the extruded material immediately after extrusion. Become. As a result, the amount of Mg ₂ Si that is effective for improving the strength during the aging treatment is reduced.

Extrusion Step In the extrusion process, heat management is performed so that the extruded material immediately after coming out of the extrusion die has a material temperature of 500 to 560 ° C.
The cooling is performed so that the cooling rate in the temperature range of 250 ° C. is 50 ° C./min or more. Material temperature and cooling rate immediately after extrusion are important for maintaining the matrix of the extruded material in a supersaturated solid solution state. Depending on the supersaturated solid solution state, a precipitate effective for imparting strength can be precipitated in an aging treatment stage in a later step.
In the case of an extruded material containing Cu, Cr, Mn, and Zr, precipitates are easily generated. Therefore, it is preferable to set the cooling rate to 1000 ° C./min or more by water quenching, mist cooling, or the like.

Straightening Step The extruded material is pulled by a straightening machine to correct the bending. At this time, when the load applied to the straightening machine changes abruptly, it is determined that the extruded material has been straightened, and the length of the extruded material at that time can be used as the original extruded material length. When the tensile force is further applied, the extruded material elongates. The ratio of the amount of elongation to the original length of the extruded material is defined as the amount of plastic strain, and the extruded material is adjusted until the amount of plastic strain becomes 0.2% or more. Thus, the extruded material is adjusted so that the proof stress value given by the aging treatment falls within a predetermined range. The straightening is preferably performed on an extruded material whose material temperature has dropped to 80 ° C. or lower. When the material temperature exceeds 80 ° C., the material temperature varies greatly depending on the position of the extruded material, and uniform strain may not be applied.

Aging treatment The extruded material is adjusted at 160 to 220 ° C. for 2 to 1
T5 treatment for 2 hours is applied. By the T5 treatment, Mg ₂ Si or the like precipitates, and the extruded material age hardens. The aging condition at this time is 160 to 2 depending on the required characteristics of the extruded material.
The heating temperature and the holding time are appropriately set within the range of 20 ° C. and 2 to 12 hours. Further, a T6 treatment in which quenching is performed after solution treatment in which the solution is kept at 480 to 580 ° C. for 1 to 8 hours, straightening is performed, and then aging treatment is performed under the same conditions, can also be adopted. The matrix of the extruded material is turned into a supersaturated solid solution state by the solution treatment, and after being quenched, is stretched by a straightening machine to correct the bending generated at the time of quenching.
A plastic strain of 2% or more is provided. The extruded material after the straightening is kept at 160 to 220 ° C. for 2 to 12 hours to age harden by precipitation of Mg ₂ Si or the like. Also in this case, the heating temperature and the holding time are appropriately set in the range of 160 to 220 ° C. and 2 to 12 hours according to the required characteristics of the extruded material.

The bending extruded material substantially stationary mold and the movable mold and each of the insertion opening having insertion opening of the same shape are disposed so that a straight line, the movable metal extrusion material from the fixed die through opening Push it into the mold opening. When the tip of the extruded material passes through the insertion opening of the movable mold, the extruded material can be freely bent by gradually moving the movable mold while continuously pushing and pushing the extruded material. The amount of movement of the movable mold is determined in consideration of the amount of springback, but this bending method is a method generally called multi-bending, which is more difficult than other bending methods such as draw bending and stretch bending.
Due to the large amount of springback and its variation,
It is necessary to keep the strength of the extruded material constant,
In bending using an Al-Mg-Si-based aluminum alloy extruded material having a plastic strain of 0.2% or more, since the proof strength of the extruded material is constant, a bent material having excellent dimensional accuracy can be obtained.

[0018]

Example 1 Nine billets of an Al-Mg-Si-based aluminum alloy 1 having the composition shown in Table 1 were prepared, and 580 ° C ×
After homogenizing for 2 hours, heat to 450 ° C.
An extruded material having a length of 40 m and a hollow rectangular cross section having a size of 100 mm and a thickness of 2 mm was produced. Next, the extruded material was cooled to 30 ° C. at an average cooling rate of 70 ° C./min by air cooling with a fan.

[0019]

Each of the obtained extruded materials was pulled by a straightening machine to impart various amounts of plastic strain, and then subjected to a T5 treatment at 180 ° C. for 4 hours. The aging treatment was performed at the time when 30 hours had passed since the end of extrusion. Table 2 shows the results of measuring the proof stress and elongation of each extruded material subjected to T5 treatment. As is clear from Table 2, the proof stress imparted by the aging treatment sharply increases up to the plastic strain amount of 0.2%, but the increase rate of the proof stress is small at the plastic strain amount of 0.2% or more. became. However, as the amount of plastic strain increased, the elongation of the aged extruded material gradually decreased.

[0021]

[0022]

Example 2 Nine billets of Al-Mg-Si-based aluminum alloy 2 were prepared, homogenized at 580 ° C for 2 hours, heated to 480 ° C, and the material temperature immediately after coming out of the extrusion die. 100 mm x 100 under the condition that
The extruded material is extruded to a shape of 40 mm in length having a hollow rectangular cross section with a thickness of 2 mm and a thickness of 2 mm.
The temperature was cooled to room temperature at a cooling rate of not less than / min. Each extruded material quenched at the die end was pulled by a straightening machine to impart various amounts of plastic strain, and then subjected to an aging treatment at 180 ° C. for 4 hours. The aging treatment was performed at the time when 30 hours had passed since the end of extrusion. Table 3 shows the results of measuring the proof stress and elongation of each of the aged extruded materials. As is clear from Table 3, in this case also, the proof stress imparted by the aging treatment sharply increases up to the plastic strain amount of 0.2%, but the proof stress is increased at the plastic strain amount of 0.2% or more. The rate of increase has been reduced.

[0023]

[0024]

Example 3 Nine billets of Al-Mg-Si-based aluminum alloy 2 were prepared, homogenized at 580 ° C for 2 hours, and then heated to 450 ° C to obtain 100 mm x 100 mm,
An extruded material having a thickness of 40 mm and a hollow rectangular cross section with a thickness of 2 mm was produced. Each of the obtained extruded materials was subjected to a solution treatment at 540 ° C. for 2 hours and then water-quenched (T6 treatment). Each extruded material subjected to T6 treatment was pulled by a straightening machine to impart various amounts of plastic strain, and then subjected to an aging treatment at 180 ° C. for 4 hours. The aging treatment is performed 3 times after the end of extrusion.
It was set at the time when 0 hour had passed. Table 4 shows the results of measuring the proof stress and elongation of each of the aged extruded materials. Table 4
As is clear from FIG.
%, The proof stress imparted by the aging treatment sharply increased, but the rate of increase in the proof stress decreased at an amount of plastic strain of 0.2% or more.

[0025]

[0026]

Example 4 The extruded material (100
2 is passed through a fixed mold 1 and a movable mold 2 at a passing speed of 90 cm / min in a pressing direction D in an atmosphere at 23 ° C. as shown in FIG. The extruded material M was moved so that the radius of curvature R of No. 2 became 200 mm. After processing, the shape of the extruded material was measured, and the radius of curvature r was determined. As can be seen from the results in Table 5, when the amount of plastic strain is 0% or 0.1%, the T5 treated material of Example 1 has 78.2 mm (48.6 + 29.6 m).
m), and 73.6 mm (40.
6 + 33 mm), 60.7 m for the T6 treated material of Example 3.
m (41.7 + 19 mm) and the radius of curvature r of the extruded material that was bent were large. From this,
It can be seen that when the amount of plastic strain is less than 0.2%, the amount of springback is greatly different even if the amount of plastic strain is slightly different.

On the other hand, when the plastic strain amounts of 0.2% and 0.4% are given, the T5 treated material of Example 1 has a thickness of 30.9 m.
m, 37.5 mm for the water-quenched material of Example 2, Example 3
In the case of the T6 treated material, the difference in the radius of curvature r of the processed extruded material is 21.5 mm, which is small even with the same change in the amount of strain. In addition, the tendency that the difference in the radius of curvature r becomes smaller as the amount of plastic strain increases becomes more conspicuous. From this,
When giving a plastic strain amount of 0.2% or more, the springback amount does not greatly change regardless of the change in the plastic strain amount,
It can be seen that a bent product having a good shape can be obtained.

[0028]

[0029]

As described above, in the present invention, an extruded material produced by extrusion processing is given a plastic strain of 2% or more before aging treatment. Due to the introduction of plastic strain, dislocations serving as precipitation nuclei such as Mg ₂ Si during the aging treatment increase to such an extent that they cancel each other out, so that an excessive increase in strength is suppressed after the aging treatment, and the proof stress is within a predetermined range. Wood is obtained. In this way,
Since the proof stress can be set within the range of the lower limit and the upper limit required by the user, an extruded material used in a wide range of fields including bending and vehicle equipment is provided.

[Brief description of the drawings]

FIG. 1 is a graph showing the effect of the amount of plastic strain given by straightening on the yield strength after aging treatment.

FIG. 2 is a diagram illustrating a bending process of an extruded material.

[Explanation of symbols]

1: fixed mold 2: movable mold M: extruded material D:
Pushing direction

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 630 C22F 1/00 630A 630K 682 682 683 683 683 685 685Z 692 692A 692B 694 694A 694B (72) Invention Person Shigeru Owaniwa 1-34-1 Kambara, Kambara-cho, Abara-gun, Shizuoka Prefecture Within the Nippon Light Metal Co., Ltd.Group Technology Center (72) Inventor Shintaku Yasunaga 1-4-1 Chuo, Wako-shi, Saitama Prefecture Honda Motor Research Institute, Inc. (72) Inventor Yasuyuki Hama 1-4-1 Chuo, Wako-shi, Saitama Pref.

Claims (7)

[Claims] 1. An extruding method comprising the steps of: extruding an Al—Mg—Si based aluminum alloy, applying a plastic strain of 0.2% or more by plastic deformation, and then performing aging treatment.
A method for producing an extruded l-Mg-Si aluminum alloy. 2. Si: 0.2 to 0.9% by weight, Mg:
0.4 to 1.2% by weight, Fe: 0.1 to 0.3% by weight,
Ti: 0.005 to 0.2% by weight, B: 0.001 to
The method for producing an extruded Al-Mg-Si-based aluminum alloy according to claim 1, wherein an Al-Mg-Si-based aluminum alloy containing 0.01% by weight and a balance substantially having an Al composition is used. 3. Cu: 0.01 to 0.4% by weight, C
r: 0.05 to 0.2% by weight, Zr: 0.05 to 0.2
The Al-Mg-Si-based aluminum alloy extruded material according to claim 2, wherein an Al-Mg-Si-based aluminum alloy containing one or more of Mn: 0.05 to 0.3% by weight is used. Production method. 4. The Al-M according to claim 1, wherein a plastic strain of 0.2% or more is imparted by straightening after extrusion.
A method for producing an extruded g-Si aluminum alloy. 5. The material temperature immediately after leaving the extrusion die is 500
Extrude an Al-Mg-Si-based aluminum alloy so that the temperature becomes ５560 ° C.
After cooling at a rate of at least / min, a plastic strain of 0.2% or more is given by straightening, and then aging treatment is performed.
A method for producing an extruded l-Mg-Si aluminum alloy. 6. An Al—Mg—Si based aluminum alloy is subjected to a solution treatment before aging treatment and quenching,
The method for producing an Al-Mg-Si-based aluminum alloy extruded material according to any one of claims 1 to 4, wherein the plastic strain is imparted. 7. A method of bending an extruded material by moving a movable mold while passing an aluminum alloy extruded material produced by the method according to claim 1 through a fixed mold and a movable mold. A method for processing extruded aluminum alloys.