JP2001158951A - METHOD OF MANUFACTURING HIGH STRENGTH Al-Mg-Si-TYPE ALUMINUM ALLOY EXTRUDED MATERIAL, AND WORKING METHOD THEREFOR - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the progress of natural aging to aging treatment and to provide an Al-Mg-Si-type aluminum alloy extruded material with highly stabilized strength by aging treatment. SOLUTION: An Al-Mg-Si-type aluminum alloy is extruded, and the resultant extruded material is held at >=20 deg.C in the course from the point of time when extrusion is completed to the point of time when aging treatment is started. As the Al-Mg-Si-type aluminum alloy, an aluminum alloy which has a composition containing 0.2-0.9% 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 0.01-0.35% 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 Al-Mg-Si based aluminum alloy extruded material having a high and stable strength.

[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. As aging treatment,
Extruded Al-Mg-Si based aluminum alloy
T5 treatment for aging at 60 to 220 ° C. and T6 treatment for solution treatment and quenching prior to aging treatment are employed. Although it is a heat treatment belonging to the T5 treatment, a die end quenching for cooling an extruded material by air cooling with a fan, water quenching, or the like immediately after extrusion processing is also known.

[0003]

SUMMARY OF THE INVENTION In the aging treatment, Mg ₂ Si
And the like are precipitated to impart strength to the Al-Mg-Si-based aluminum alloy. However, Al with the same manufacturing history
-Even in the case of an extruded material of an Mg-Si-based aluminum alloy, the strength after aging treatment is sometimes different. When the present inventors investigated the cause of the strength fluctuation, they found that the cause was the condition in which the extruded material was stored from the end of extrusion to the start of aging treatment. The present invention has been devised based on this finding, and by controlling the holding conditions until the aging treatment, an Al-Mg-Si-based aluminum which is given a high and stable strength by the aging treatment. An object of the present invention is to provide an extruded alloy material.

[0004]

According to the production method of the present invention, in order to achieve this object, the profile temperature immediately after extrusion is 510 to 510.
After extruding the Al-Mg-Si-based aluminum alloy to 560 ° C and cooling between 450 to 200 ° C at a cooling rate of 50 ° C / min or more, between the steps from the end of extrusion to the start of aging treatment. Extruded material at a temperature above 20 ° C
It is characterized by performing a aging treatment for holding for at least 160 hours at 160 to 220 ° C. for 2 to 12 hours.

An aluminum alloy extruded material produced by holding an extruded material at a temperature of 20 ° C. or more for 12 hours or more between the steps from the end of extrusion to the start of aging treatment is transferred to a fixed mold and a movable mold. Bending is performed by moving the movable mold while passing. As an Al-Mg-Si-based aluminum alloy, 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.
An aluminum alloy containing 001 to 0.01% by weight is used.

Further, Cu: 0.01 to 0.4% by weight, C
r: 0.05 to 0.2% by weight, Zr: 0.05 to 0.2
In the case of using an Al-Mg-Si-based aluminum alloy containing one or more of 0.05% to 0.3% by weight of Mn: 0.05 to 0.3% by weight, the die is quenched after extrusion or quenched by solution treatment. After the quenching, the extruded material is kept at a temperature of 45 ° C. or more between the steps from the end of the quenching to the start of the aging treatment. The extruded material may be subjected to die end quenching or T6 treatment (solution-hardening) before aging treatment.
In such a case, the extruded material is kept at a temperature of 20 ° C. or more or 45 ° C. or more between the steps from the end of quenching after die end quenching or quenching after solution treatment to the start of aging treatment.

[0007]

The present inventors have conducted various investigations on the causes of the variation in strength imparted by the aging treatment. As a result, in the case of T5 material, the time from the end of extrusion to the aging treatment, and in the case of the die quenched material, It was found that there was a cause in the time from the quenching of the die end to the aging treatment, and in the case of T6 material, in the period from the end of quenching after the solution treatment to the aging treatment. This period is the waiting time until the aging furnace becomes an empty furnace,
The extruded material is left in the factory and is exposed to an atmosphere at a temperature below freezing to about 50 ° C. depending on the season, weather, and the like. If the extruded material is left for a long time in the temperature range of below freezing to about 50 ° C,
It was found that the progress of natural aging differs depending on the temperature. That is, the natural aging that proceeds at a temperature of less than 80 ° C., which was conventionally considered to be constant regardless of the temperature, had a different effect depending on the temperature on the strength after the aging treatment.

Specifically, as shown in FIG. 1, which shows the effect of the holding temperature and the holding time on the 0.2% proof stress of a 6063 aluminum alloy extruded material subjected to T5 treatment at 180 ° C. for 6 hours, When the extruded material held in the temperature atmosphere of 20 ° C. or more is subjected to the aging treatment, the yield strength equal to or higher than that of the extruded material subjected to the aging treatment immediately after the extrusion is obtained. On the other hand, the aging treatment of the extruded material held in an atmosphere at a temperature lower than 20 ° C. provided only a considerably lower proof stress as compared with the extruded material subjected to the aging treatment immediately after the extrusion. After solution treatment at 560 ° C. × 1 hour, water quenching
606 with T6 treatment for aging at 80 ° C for 6 hours
As shown in FIG. 2, when the aluminum alloy extruded material was subjected to the holding treatment at a temperature of 45 ° C. or more as shown in FIG. 2, a yield strength equal to or higher than that of the extruded material subjected to the aging treatment immediately after the extrusion was obtained. In this case, even at a holding temperature of 20 ° C., the proof stress tends to decrease depending on the holding time.

The effect of the holding temperature on the strength after the aging treatment is presumed as follows. When the extruded material is kept in an atmosphere at a temperature lower than 20 ° C., more precipitates that do not contribute to the improvement of the proof stress, which are generally called clusters, precipitate more than the GP zone that contributes to the improvement of the proof strength, and are effective in improving the proof strength to be deposited by aging treatment. Mg ₂ Si or the like tends to be insufficient. This tendency is conspicuous in Al-Mg-Si alloys containing Cu, Cr, Zr, Mn, etc., and a large amount of precipitates that do not contribute to the improvement in proof stress are deposited even at a holding temperature of less than 45 ° C. The holding process is preferably set for 3 hours or more, more preferably 24 hours or more. By the holding treatment for 3 hours or more, a large amount of precipitates contributing to the improvement in proof stress are precipitated, and the precipitates become precipitation nuclei during the aging treatment to promote precipitation of Mg ₂ Si or the like, thereby further increasing the proof stress. When the holding treatment is performed for more than 24 hours, the effect of improving the yield strength due to the precipitate is saturated, and an extruded material having a constant yield strength is obtained.

Next, the Al-Mg-
The alloy components and contents of the Si-based aluminum alloy will be described. 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, excessive Ti content exceeding 0.2% by weight 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, excessive B content exceeding 0.01% by weight deteriorates extrudability. Cu: 0.01 to 0.4% by weight An alloy component added as necessary. When the content is 0.01% by weight or more, the effect of improving mechanical strength becomes remarkable. However, if 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 In extrusion, the temperature of the profile immediately after extrusion is 510-560 ° C.
The temperature is controlled so as to fall within the range. If the temperature of the profile immediately after extrusion is less than 510 ° C., Mg and Si do not form a solid solution, and the amount of precipitation necessary for imparting strength tends to be insufficient in the aging treatment in the subsequent step. Conversely, at a profile temperature exceeding 560 ° C., the recrystallized grain structure after extrusion tends to become coarse, and the mechanical strength tends to decrease. The shape after extrusion is 450-20
It is cooled at a cooling rate of 50 ° C./min or more in a temperature range of 0 ° C.
When controlling the cooling rate in this way, Mg,
Precipitation of Si and the like is prevented, and the amount of precipitation necessary for imparting strength is ensured in the aging treatment in a later step.

The aging-treated extruded material is maintained at 160 to 220 ° C. for 2 to 12 hours.
Five processes are performed. By the T5 treatment, Mg ₂ Si or the like precipitates, and the extruded material age hardens. The aging conditions at this time are:
160-220 ° C and 2-1 depending on the required properties of the extruded material
The heating temperature and the holding time are appropriately set within a range of 2 hours. T6 which is quenched after solution treatment at 480 to 580 ° C. for 1 to 8 hours and is aged under similar conditions
Processing can also be employed. The matrix of the extruded material is brought into a supersaturated solid solution state by the solution treatment, and
By holding at 2 ° C. for 2 to 12 hours, age hardening occurs due to 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.

A fixed mold and a movable mold having an insertion opening having substantially the same shape as the bent extruded material are arranged so that the respective insertion openings are aligned, and the extruded material is moved from the insertion opening of the fixed mold to the movable mold. 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 of the extruded material, but this bending method is a method generally called multi-bending, which is different from other bending methods such as draw bending and stretch bending. Since the amount of springback and its variation are large, it is necessary to keep the proof strength of the extruded material constant. During the process from the end of the extrusion to the start of the aging treatment, when the extruded material is kept at a temperature of 20 ° C. or more, the precipitation nucleus such as Mg ₂ Si during the aging treatment precipitates. When the time exceeds 12 hours, precipitation hardly occurs, and the yield strength of the extruded material becomes constant. As a result, a bent material having excellent dimensional accuracy can be obtained. When the holding process is further continued and the holding time exceeds 24 hours, precipitation of Mg ₂ Si or the like hardly occurs, and a bent material having more excellent dimensional accuracy can be obtained.

[0017]

Example 1 A billet of an Al-Mg-Si-based aluminum alloy 1 having a composition shown in Table 1 was homogenized at 580 ° C for 2 hours, and then heated to 450 ° C and 100 mm x 100
An extruded material having a length of 40 m and a hollow rectangular cross section having a thickness of 2 mm and a thickness of 2 mm was produced.

[0018]

Each of the obtained extruded materials was cooled from 520 ° C. to room temperature by a fan air cooling at a cooling rate of 70 ° C./min, and was kept at various times and temperatures as shown in Table 2 until the aging treatment was started. Thereafter, aging treatment was performed at 180 ° C. for 6 hours.
The proof stress of the aged extruded material was measured, and the effect of holding conditions on the proof stress imparted by the aging treatment was investigated. For comparison, the proof stress of the extruded material subjected to the aging treatment immediately after the extrusion was similarly measured. As is evident from the investigation results in Table 2, the proof stress of the extruded material held in a temperature atmosphere of 20 ° C. or higher showed a value equal to or higher than that of the extruded material subjected to the aging treatment immediately after extrusion. On the other hand, in the extruded material held at 10 ° C. for 12 hours or more, the strength imparted by the aging treatment was significantly reduced.

[0020]

[0021]

Example 2 After a billet of an Al—Mg—Si based aluminum alloy 2 was homogenized at 580 ° C. for 2 hours,
It was heated to 0 ° C. and extruded into a 40 mm long shape having a hollow rectangular cross section of 100 mm × 100 mm and a thickness of 2 mm. Each extruded material was subjected to T6 treatment of 540 ° C. × 1 hour → water cooling. Until the aging treatment is started for each extruded material subjected to T6 treatment,
After holding for various times and temperatures as shown in Table 3,
An aging treatment was performed at 80 ° C. for 6 hours. The proof stress of the aged extruded material was measured, and the effect of holding conditions on the proof stress imparted by the aging treatment was investigated. For comparison, the proof strength of the extruded material immediately after quenching was measured similarly. As is clear from the investigation results in Table 3, the proof strength of the extruded material kept at a temperature of 40 ° C. or more from the end of quenching after the solution treatment to the aging treatment was as follows. A value equivalent to the yield strength was shown. On the other hand, in the extruded material held at 20 ° C. for 3 hours or more, the strength imparted by the aging treatment was significantly reduced.

[0022]

[0023]

Example 3 The extruded material (100 × 1) produced in Example 1
After a hollow material having a thickness of 00 mm and a thickness of 2 mm) is held in an atmosphere at 23 ° C., the material is passed through the fixed mold 1 and the movable mold 2 in the pushing direction D at a passing speed of 90 cm / min as shown in FIG. The extruded material M was bent by moving the movable mold 2 so that the radius of curvature R became 200 mm. The radius of curvature r of the extruded material M was determined by measuring the shape of the processed extruded material M, and the effect of the holding treatment on the radius of curvature r was investigated.

As can be seen from the investigation results in Table 4, when the holding time is 0 hour and 12 hours, when the holding temperature is 20 ° C., 79.5 mm (49.3 + 30.2 mm) and the holding temperature 4
199mm (139.2 + 59.8mm) at 0 ° C
And the difference in the radius of curvature r of the processed extruded material M was large. That is, when the holding temperature is less than 12 hours, the amount of springback greatly changes even if the holding temperature is slightly different. On the other hand, when the holding temperature is 20 ° C. when the holding temperature is 12 hours and 24 hours, 17.5 m
m, 24.1 mm when the holding temperature is 40 ° C., the same 1
The difference in the radius of curvature r of the processed extruded material M is small even with a difference of 2 hours. This tendency becomes more remarkable as the holding time becomes longer. Therefore, when the holding time is set to 12 hours or more, it is understood that the springback amount does not change significantly even if the holding time changes.

[0025]

[0026]

As described above, in the present invention, the extruded material is held in an atmosphere of 20 ° C. or more from the end of extrusion or the end of quenching after solution treatment to the start of aging treatment. , Controlling the progress of natural aging. Therefore, the amount of precipitation of Mg ₂ Si or the like effective for imparting strength is secured by the aging treatment, and an aging material having a high and stable strength can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing the effect of holding temperature and holding time on the proof stress value of a 6063-T5 material.

FIG. 2 is a graph showing the effect of holding temperature and holding time on the proof stress value of the 6061-T6 material.

FIG. 3 is a diagram illustrating bending of an extruded material.

[Explanation of symbols]

1: fixed mold 2: movable mold R: radius of curvature of movable mold M: extruded material D: pushing direction

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 602 C22F 1/00 602 612 612 630 630 630A 683 683 691 691B 692 692A 693 693A 693B (72) Invention Person Shigeru Owaniwa 1-34-1 Kambara, Kambara-cho, Abara-gun, Shizuoka Prefecture Inside the Nippon Light Metal Co., Ltd. Group Technical Center (72) Inventor Takayuki Tsuchida 1-34-1 Kambara, Kambara-cho, Abara-gun, Shizuoka Prefecture Nippon Light Metal Group Technology Inside the center (72) Inventor Akihiro Mori 161 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture Inside the Nippon Light Metal Co., Ltd.Kamahara Factory (72) Inventor Masakazu Iwase 20-1, Shimoda-cho, Sakai-shi, Osaka Nippon Light Metal Corporation Osaka Plant (72) Inventor Shintaku Yasunaga Sai Prefecture Wako center chome No. 4 No. 1 stock company Honda intra-technology Research Institute (72) inventor beach Yasuyuki Wako, Saitama center chome No. 4 No. 1 stock company Honda R & D in the F-term (reference) 4E029 AA06 EA05

Claims (4)

[Claims] 1. The temperature of a profile immediately after extrusion is 510 to 560 ° C.
An Al-Mg-Si-based aluminum alloy is extruded so as to obtain an extruded material between 450-200 ° C at a cooling rate of 50 ° C / min or more and between the end of extrusion and the start of aging treatment. Characterized in that a high-strength Al-Mg-S is subjected to a holding treatment at a temperature of 20 ° C or higher for 3 hours or more, and an aging treatment at 160 to 220 ° C for 2 to 12 hours.
A method for producing an i-based 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. 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
0.01% by weight, Cu: 0.01 to 0.4% by weight, Cr: 0.05 to 0.2% by weight, Zr: 0.05
After extruding an Al-Mg-Si-based aluminum alloy containing one or more of 0.2 to 0.2% by weight and Mn: 0.05 to 0.3% by weight, a die end quenching or solution treatment is performed. A method for producing a high-strength Al-Mg-Si-based aluminum alloy, comprising: extruding a material at a temperature of 45 ° C or higher between the steps from the end of quenching to the start of aging after quenching. 4. The aluminum alloy extruded material according to claim 2, which is produced by holding the extruded material at a temperature of 20 ° C. or more for 12 hours or more between steps from the end of extrusion to the start of aging treatment. A method for processing an extruded aluminum alloy, wherein the bending is performed by moving the movable mold while passing through the mold and the movable mold.