JP2014074213A - High strength aluminum alloy extruded material and method of producing the same - Google Patents

Abstract

A high-strength aluminum alloy extruded material excellent in corrosion resistance, extrudability and surface quality after extrusion is provided.
Si: 0.70 to 1.3% (mass%, hereinafter the same), Mg: 0.45 to 1.2%, Cu: 0.15 to less than 0.40%, Mn: 0.10 -0.40%, Cr: 0.06% or less (not including 0%), Zr: 0.05-0.20%, Ti: 0.005-0.15% contained, Fe: 0.0. 30% or less, V: regulated to 0.01% or less, having a chemical component consisting of the balance Al and inevitable impurities, the grain size of the crystallized product being regulated to 5 μm or less, parallel to the hot extrusion direction A high-strength aluminum alloy extruded material characterized in that the area ratio of the fibrous structure in the cross section is 95% or more.
[Selection] Figure 1

Description

  The present invention relates to an extruded material made of a high-strength aluminum alloy.

  The 6000 series aluminum alloy material is excellent in strength and corrosion resistance, and is used for applications such as mechanical parts and structural members. In recent years, studies have been made to apply a 6000 series aluminum alloy material to frames of transportation equipment including automobiles to reduce the weight of the frames.

  Examples of the high-strength aluminum alloy material suitably used for automobiles and the like include an aluminum alloy extruded material described in Patent Document 1 and an aluminum alloy forged material described in Patent Document 2. The aluminum alloy extruded material described in Patent Document 1 has been proposed as an aluminum extruded material having a central portion composed of a fibrous structure and both surface layer portions composed of a recrystallized structure, and having excellent impact absorption characteristics. Moreover, the aluminum alloy forging material described in Patent Document 2 is intended to increase the strength by adding 0.4 to 1.2% by weight of Cu in addition to Mg and Si.

JP 2001-355032 A JP-A-6-330264

  The 6000 series aluminum alloy manufactured by the conventional component range and the conventional manufacturing method generally has lower strength than the ferrous material used for the frame. Therefore, it is necessary to increase the plate thickness or to give a shape for reinforcement by forging or the like, and there is a problem that productivity is low. Therefore, it has been anxious to produce a high-strength aluminum alloy material having a yield strength of 350 MPa or more by extrusion processing with high productivity.

  However, the aluminum alloy extruded material described in Patent Document 1 has a tensile strength of about 300 MPa, and the strength is insufficient for use in place of an iron-based material.

  Although the aluminum alloy described in Patent Document 2 is higher in strength than the conventional 6000 series aluminum alloy, it is a forged material and has the following problems in performing extrusion processing. That is, when the aluminum alloy described in Patent Document 2 is extruded at a high speed during the extrusion process, the surface peels off due to friction with a die or the like, resulting in defects on the surface accompanying the extrusion process, and the surface quality is degraded. There was a fear.

  Moreover, since the aluminum alloy forging material described in Patent Document 2 has a relatively high Cu content as a 6000 series aluminum alloy, the corrosion resistance is inferior.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a high-strength aluminum alloy extruded material excellent in corrosion resistance, extrusion processability, and surface quality after extrusion.

In one embodiment of the present invention, Si: 0.70 to 1.3% (mass%, the same applies hereinafter), Mg: 0.45 to 1.2%, Cu: 0.15 to less than 0.40%, Mn: 0.10 to 0.40%, Cr: 0.06% or less (not including 0%), Zr: 0.05 to 0.20%, Ti: 0.005 to 0.15%, Fe : 0.30% or less, V: 0.01% or less, having a chemical component consisting of the balance Al and inevitable impurities,
The crystallized particle size is regulated to 5 μm or less,
The high strength aluminum alloy extruded material is characterized in that the area ratio of the fibrous structure in a cross section parallel to the hot extrusion direction is 95% or more.

Other aspects of the present invention include Si: 0.70 to 1.3% (mass%, the same applies hereinafter), Mg: 0.45 to 1.2%, Cu: 0.15 to less than 0.40%, Mn : 0.10 to 0.40%, Cr: 0.06% or less (not including 0%), Zr: 0.05 to 0.20%, Ti: 0.005 to 0.15%, Fe: 0.30% or less, V: 0.01% or less, to produce an ingot having a chemical component consisting of the balance Al and inevitable impurities,
A homogenization treatment is performed in which the ingot is held at a temperature of 450 ° C. or higher and lower than 500 ° C. for 2 to 30 hours,
Then, in the state where the temperature of the ingot at the start of processing is 480 ° C. to 540 ° C., the ingot is subjected to hot extrusion to obtain an extruded material,
While the temperature of the extruded material is 480 ° C. or higher, it is rapidly cooled to 150 ° C. or lower at a cooling rate of 2 to 100 ° C./second,
Thereafter, the extruded material is subjected to an aging treatment in which the extruded material is heated at a temperature of 150 ° C. to 200 ° C. for 1 to 24 hours (claim 3).

The high-strength aluminum alloy extruded material has the specific chemical component. Therefore, the high-strength aluminum alloy extruded material is excellent in corrosion resistance and extrusion processability, and easily becomes a high-strength extruded material.
The high-strength aluminum alloy extruded material regulates the crystallized particle size to 5 μm or less. Therefore, the high-strength aluminum alloy extruded material is less likely to be peeled off during extrusion, and tends to be excellent in surface quality after extrusion.
The high strength aluminum alloy extruded material has an area ratio of a fibrous structure in a cross section parallel to the hot extrusion direction of 95% or more. Therefore, the high-strength aluminum alloy extruded material tends to have a proof stress of 350 MPa or more.

  That is, the high-strength aluminum alloy extruded material is excellent in corrosion resistance, extrudability and surface quality after extrusion, due to a synergistic effect of the specific chemical component and the metal structure controlled as described above, and It becomes a high-strength extruded material having a yield strength of 350 MPa or more.

  Next, the manufacturing method of the said high strength aluminum alloy extruded material manufactures the said high strength aluminum alloy extruded material with the said specific process temperature, process time, and a process procedure. Thereby, the said high intensity | strength aluminum alloy extrusion material can be obtained easily.

In Example 1, the sample No. 1 with a high area ratio of the fibrous tissue was used. 1 is a metal structure photograph. In Example 1, the sample No. 2 with a low area ratio of the fibrous tissue was used. 10 metallographic photographs.

The high-strength aluminum alloy extruded material contains both 0.70% and 1.3% Si and 0.45% and 1.2% Mg. Si and Mg coexist in the alloy to precipitate Mg ₂ Si particles during the aging treatment, and have the effect of improving the strength of the extruded material by precipitation strengthening. Further, excess Si is not precipitated as Mg 2 _Si particles have an effect of such refining the Mg 2 _Si particles, this contributes to an increase in the strength of the extruded material.

When the Si content is less than 0.7%, the precipitation amount of Mg ₂ Si particles decreases, so the strength of the obtained extruded material decreases. Therefore, the Si content is preferably 0.7% or more, and more preferably 0.85% or more. On the other hand, when the content of Si exceeds 1.3%, defects such as peeling are likely to occur on the surface of the extruded material during the extrusion process, and the surface quality of the obtained extruded material tends to deteriorate. Therefore, the Si content is preferably 1.3% or less, and more preferably 1.2% or less.

Further, when the Mg content is less than 0.45%, the amount of Mg ₂ Si particles deposited decreases, so that the strength of the obtained extruded material becomes low. Therefore, the content of Mg is preferably 0.45% or more, and more preferably 0.6% or more. On the other hand, if the Mg content exceeds 1.2%, the extrusion processability deteriorates, such as an increase in the extrusion pressure during the extrusion process. The productivity of the material tends to decrease. Therefore, the content of Mg is preferably 1.2% or less, and more preferably 0.9% or less.

  Moreover, content of Cu is 0.15% or more and less than 0.40% among the said chemical components. Cu dissolves in the alloy and has the effect of improving the strength of the extruded material by strengthening the solid solution. When the Cu content is less than 0.15%, the Cu content is insufficient, so the strength of the obtained extruded material is lowered. Therefore, the content of Cu is preferably 0.15% or more, and more preferably 0.20% or more. On the other hand, when the Cu content is 0.40% or more, the extrusion processability is deteriorated, so that the surface quality and productivity of the obtained extruded material are likely to be lowered. In this case, the corrosion resistance tends to deteriorate. Therefore, the Cu content is preferably less than 0.40%, more preferably 0.38% or less.

  Of the above chemical components, the Mn content is 0.10% or more and 0.40% or less, the Cr content is 0.06% or less (not including 0%), and the Zr content Is 0.05% or more and 0.20% or less.

  Mn, Cr and Zr form Al—Mn, Al—Mn—Si, Al—Cr, and Al—Zr fine intermetallic compounds with Al. The intermetallic compound has the effect of suppressing recrystallization by being precipitated in the alloy and increasing the ratio of the fibrous structure in the extruded material. Therefore, when the content of these three elements is excessively small, the ratio of the fibrous structure in the obtained extruded material becomes small, and the strength of the extruded material may be reduced. On the other hand, when the contents of Mn, Cr and Zr are excessively large, the intermetallic compound becomes coarse, and defects such as exfoliation are easily generated on the surface of the extruded material during the extrusion process. The surface quality of the material tends to deteriorate.

  Mn, Cr, and Zr each have an action of suppressing recrystallization, but the effect can be further improved by adding these three elements in combination. Therefore, by adjusting the contents of Mn, Cr and Zr to the specific ranges, it is possible to suppress the precipitation of coarse intermetallic compounds while increasing the ratio of the fibrous structure in the extruded material.

  Moreover, content of Ti is 0.005% or more and 0.15% or less among the said chemical components. Ti has an effect of refining the ingot structure and an effect of increasing the ratio of the fibrous structure in the extruded material. When the Ti content is less than 0.005%, the ingot structure is not sufficiently refined or the ratio of the fibrous structure is lowered, so that the strength and surface quality of the obtained extruded material are low. It tends to decrease. On the other hand, when the Ti content exceeds 0.15%, an Al—Ti coarse crystallized product is easily formed between the Ti content. For this reason, defects such as peeling are likely to occur on the surface of the extruded material during the extrusion process, and the surface quality of the obtained extruded material is likely to deteriorate.

  Moreover, among the chemical components, the Fe content is regulated to 0.30% or less, and the V content is regulated to 0.01% or less. When the content of Fe and V is excessively large, it becomes easy to form a coarse crystallized product. Therefore, defects such as exfoliation are likely to occur on the surface of the extruded material during extrusion processing, and the surface quality of the obtained extruded material. Is prone to decline. Such deterioration of the surface quality can be avoided by regulating the Fe content to 0.30% or less and the V content to 0.01% or less. Although there is no lower limit to the contents of Fe and V, it is necessary to use high-purity aluminum ingots to reduce the contents of Fe and V, resulting in an increase in cost. In order to avoid an excessive cost increase, for example, the Fe content can be 0.05% or more.

  The high-strength aluminum alloy extruded material may contain 0.20% or less of Zn. Zn is an impurity mixed when a recycled material is used. However, if the content is 0.20% or less, the performance is not adversely affected. When the Zn content exceeds 0.20%, the corrosion resistance of the obtained extruded material may be lowered.

  Furthermore, in the high-strength aluminum alloy extruded material, the grain size of the crystallized product is regulated to 5 μm or less. Crystallized substances present in the metal structure of the extruded material are likely to be the starting point of the exfoliated portion when the surface of the extruded material is exfoliated during the extrusion process. Therefore, by restricting the particle size of the crystallized product to 5 μm or less, defects during extrusion processing can be reduced, and the surface quality of the extruded material can be improved.

  The particle size of the crystallized product can be measured, for example, by the following method. First, the extruded material is cut to expose a cross section, and the cross section is polished to obtain a smooth surface. Then, the said smooth surface is observed with an optical microscope, the crystallization thing in the obtained microscope image is approximated by an ellipse, and let the length of the major axis direction of the said ellipse be a particle size.

  Moreover, the said high-strength aluminum alloy extruded material can improve the surface quality of the said extruded material, so that there is little content of a crystallization thing. The content of the crystallized product can be, for example, 1% or less. The crystallized content is obtained by, for example, obtaining a microscopic image in the same manner as the particle size measurement method described above, and then calculating the area ratio of the crystallized product in the microscopic image by image processing. It can be.

  The high strength aluminum alloy extruded material has an area ratio of a fibrous structure in a cross section parallel to the hot extrusion direction of 95% or more. When a fibrous structure is included in the metal structure of the extruded material, mechanical properties such as tensile strength and yield strength in the extrusion direction are improved. Therefore, the extruded material has a high strength by controlling the area ratio of the fibrous structure to 95% or more. For example, the metal structure of the extruded material is subjected to electrolytic etching for 1 minute at 20 ° C. and 20 V using Barker's liquid after electrolytic polishing is performed on the cross section of the extruded material. Then, it can confirm by observing the cross section after an etching using a polarizing microscope. Moreover, the calculation method of the area ratio of a fibrous structure is demonstrated in detail in an Example.

  Here, as the cross section parallel to the hot extrusion direction described above, a cross section that can represent the ratio of the fibrous structure existing in the metal structure is arbitrarily selected from various cross sections parallel to the hot extrusion direction. Can do. That is, the cross section parallel to the hot extrusion direction can be appropriately selected according to the shape of the extruded material. For example, when the extruded material has a round bar shape, a cross section passing through the central axis can be selected. When the extruded material has a square bar shape, a cross section that passes through the central axis and is perpendicular to either the width direction or the thickness direction can be selected. In addition, when the extruded material has a shape having a plate-like portion, such as being formed in an approximately L shape when viewed from the extrusion direction, a cross section parallel to the thickness direction of the plate-like portion can be selected. . The method of selecting the cross section described above is an example, and the present invention is not limited to this.

  As described above, the high-strength aluminum alloy extruded material having the specific chemical component and the specific metal structure is higher in strength than the 6000 series aluminum alloy material produced by the conventional component range and the conventional manufacturing method. It has excellent corrosion resistance and surface quality. Therefore, the high-strength aluminum alloy extruded material can be suitably used as a vehicle structural member (claim 2).

  That is, the high-strength aluminum alloy extruded material can exhibit good characteristics even in a severe use environment such as vibration and corrosion, and can be suitably used for, for example, an automobile side frame or door ash. Moreover, when using the said high-strength aluminum alloy extruded material as a structural member for vehicles, what has a yield strength of 350 Mpa or more can be used especially suitably.

  Next, a method for producing the high-strength aluminum alloy extruded material will be described. In the manufacturing method of the high-strength aluminum alloy extruded material, first, an aluminum alloy ingot having the specific chemical component is prepared. Here, when producing the said ingot, it is preferable to control the cooling rate from tapping to completion of solidification to 0.2 ° C./second or more. By controlling the cooling rate at the time of casting as described above, it becomes easy to reduce the particle size of the crystallized substance formed in the ingot.

  Next, the homogenization process which hold | maintains the said ingot at the temperature of 450 to 500 degreeC for 2 to 30 hours is performed. When the holding temperature of the homogenization treatment is lower than 450 ° C., the ingot segregation layer in the ingot structure is not sufficiently homogenized. As a result, coarsening of crystal grains, formation of a non-uniform crystal structure, and the like occur, so that the surface quality of the finally obtained extruded material may be deteriorated. On the other hand, when the holding temperature exceeds 500 ° C., AlZr-based precipitates undergo transformation, and thus the effect of suppressing recrystallization is reduced. Therefore, the ratio of the fibrous structure in the obtained extruded material may be reduced. Therefore, the holding temperature in the homogenization treatment is preferably 450 ° C. or higher and lower than 500 ° C.

  Moreover, it is preferable that the holding time of the said homogenization process is 2 hours or more. When the holding time is less than 2 hours, homogenization of the ingot segregation layer in the ingot structure becomes insufficient, and thus the surface quality of the finally obtained extruded material may be reduced in the same manner as described above. . On the other hand, when the retention time of the homogenization treatment exceeds 30 hours, the ingot segregation layer is sufficiently homogenized, and therefore no further effect can be expected. Therefore, the holding time for the homogenization treatment is preferably 2 hours or more and 30 hours or less.

  After the homogenization treatment, the ingot is hot-extruded in a state where the temperature of the ingot is 480 ° C to 540 ° C to obtain an extruded material. When the temperature of the ingot before extrusion is less than 480 ° C., the added element may not be sufficiently infiltrated, so that the strength of the obtained extruded material may be reduced. On the other hand, when the temperature of the ingot before extrusion exceeds 540 ° C., eutectic melting may occur locally due to heat generated during the extrusion process. Therefore, the surface quality of the obtained extruded material may be deteriorated.

  Moreover, it is preferable to perform the said hot extrusion process within 5 hours after the temperature of the said ingot reaches | attains in the range of 480 degreeC-540 degreeC. If hot extrusion is not performed within 5 hours, the AlZr-based precipitate may be transformed, and the effect of suppressing recrystallization may be reduced.

  After the extrusion, the extruded material obtained by the hot extrusion process is rapidly cooled to 150 ° C. or lower at a cooling rate of 2 to 100 ° C./second while the temperature is 480 ° C. or higher (hereinafter, the extruded material is rapidly cooled). This is sometimes called “quick cooling”.) When the temperature before the extruded material is rapidly cooled is less than 480 ° C., quenching may be insufficient, and the strength of the obtained extruded material may be reduced. Moreover, when the temperature of the extruded material after being rapidly cooled exceeds 150 ° C., quenching may be insufficient, and the resulting extruded material may have low strength.

  Moreover, when the said cooling rate exceeds 100 degrees C / second, the effect corresponding to it cannot be acquired. On the other hand, when the cooling rate is less than 2 ° C./second, quenching becomes insufficient, and the strength of the obtained extruded material may be lowered.

  The extruded material can be rapidly cooled by cooling the extruded material by a forced means. As the cooling means used for the rapid cooling, methods such as fan air cooling, mist cooling, shower cooling, or water cooling can be employed.

  The extruded material after being rapidly cooled as described above is subjected to an aging treatment in which the extruded material is heated at a temperature of 150 to 200 ° C. for 1 to 24 hours. When the temperature in the aging treatment is less than 150 ° C., the aging effect is insufficient, and the strength of the obtained extruded material may be lowered. On the other hand, when the temperature in the aging treatment exceeds 200 ° C., overaging occurs, and the strength of the obtained extruded material may be lowered.

  Moreover, when the heating time in the said aging treatment is less than 1 hour, it will become a sub-aging and there exists a possibility that the intensity | strength of the extrusion material obtained may become low. On the other hand, when the heating time in the aging treatment exceeds 24 hours, overaging occurs, so that the strength of the obtained extruded material may be lowered.

Example 1
In this example, the chemical component of the high-strength aluminum alloy extruded material was examined. In this example, as shown in Table 1, alloys (alloys No. A to No. M) having various chemical components were used, and samples (samples No. 1 to No. 13) were manufactured under the manufacturing conditions shown in Table 2. ), And the strength measurement, metal structure observation, surface quality evaluation, and corrosion resistance evaluation of each sample were performed. The manufacturing conditions and strength measurement method, metal structure observation method, surface quality evaluation method, and corrosion resistance evaluation method of each sample will be described below.

<Sample manufacturing conditions>
An ingot having a diameter of 90 mm having the chemical components described in Table 1 was cast by continuous casting. Then, the homogenization process which hold | maintains this ingot for 10 hours at the temperature of 480 degreeC was performed. Thereafter, in the state in which the temperature of the ingot is the temperature shown in Table 2, the ingot is hot-extruded at an extrusion speed of 10 m / min to give a flat bar shape having a width of 35 mm and a thickness of 3 mm. Was made. Thereafter, in the state where the temperature of the extruded material was the temperature shown in Table 1, a rapid cooling treatment was performed to cool the stretched material to the temperature shown in Table 2 at a cooling rate of 10 ° C./second. And the aging treatment which heated the said wrought material which performed the said rapid cooling process at 180 degreeC for 6 hours was implemented, and it was set as the sample (sample No.1-No.13).

<Strength measurement method>
A test piece (metal material tensile test piece No. 5 test piece) was sampled from the sample by a method in accordance with JIS Z2241 (ISO 6892-1), and the proof stress was measured. As a result, those showing a yield strength of 350 MPa or more were determined to be acceptable.

<Metallic structure observation method>
After cutting the sample so that the dimension in the width direction was halved, the particle size measurement of the crystallized substance on the cut surface and the calculation of the area ratio of the fibrous structure were performed by the following methods.

  In measuring the particle size of the crystallized product, first, a smooth surface was obtained by polishing the cut surface. And five places were selected at random from the smooth surface, and microscopic images of these five places were obtained at a magnification of 500 times using an optical microscope. Thereafter, image analysis was performed on the microscopic image, and the maximum value among the particle sizes of the crystallized substances calculated using the above-described method by elliptic approximation was obtained. A crystallized product having a maximum particle size of 5 μm or less was determined to be acceptable.

  In the calculation of the area ratio of the fibrous structure, after electropolishing and etching the cut surface by the above-described method, the cut surface after etching is etched with an optical microscope so that the entire range in the thickness direction is in the field of view. Microscopic images were acquired. Thereafter, image analysis was performed on the obtained microscopic image, and the area ratio of the fibrous structure to the entire metal structure was calculated. An area ratio of the fibrous structure thus obtained was determined to be a preferable result.

<Surface quality evaluation method>
The surface of the sample was visually observed to check for the presence of defects such as stripping of the surface and streak-like scratches formed in the extrusion direction. Those in which these defects were not found were judged as acceptable.

<Corrosion resistance evaluation method>

  Each sample was subjected to a salt spray test by a method based on JIS Z2371, and the maximum corrosion depth after 1000 hours of the test time was measured. As a result, those having a maximum corrosion depth of 200 μm or less were determined to be acceptable.

  The evaluation results of each sample are shown in Table 3. In addition, about what was not determined to be acceptable or not preferable in each evaluation result, the evaluation result in Table 3 is underlined.

  As known from Table 3, sample no. 1-No. No. 3 passed in all evaluation items, and showed excellent properties in all of strength, corrosion resistance, extrusion processability and surface quality. As a representative example of a sample having excellent characteristics, FIG. 1 shows a microscopic image used for calculating the area ratio of the fibrous structure in FIG. As shown in FIG. 1, in the sample metal structure having excellent characteristics, a recrystallized structure is generated only in the very vicinity of the surface, and most of the inside of the sample is a fibrous structure in a direction parallel to the extrusion direction. It is made up of.

Sample No. No. 4 was judged to be unacceptable because the Si content was too small.
Sample No. No. 5 was judged to be unacceptable because peeling of the surface was observed after extrusion because the Si content was too high.

Sample No. No. 6 was judged to have failed proof stress because the Mg content was too small.
Sample No. No. 7 was judged to be unacceptable because the Mg content was too high, exfoliation of the surface was observed after extrusion.

Sample No. In No. 8, since the Cu content was too small, the yield strength was judged to be unacceptable.
Sample No. No. 9 was judged to be unacceptable because the Cu content was too high, peeling of the surface was observed after the extrusion process, and the corrosion resistance was inferior.

  Sample No. No. 10 was judged to be unacceptable due to a decrease in the area ratio of the fibrous structure because the respective contents of Mn, Cr, and Zr were too small, resulting in a decrease in yield strength. As a representative example of a sample having a low area ratio of the fibrous tissue, FIG. The microscope image used for calculation of the area ratio of the fibrous structure in 10 is shown. As shown in FIG. 2, the metal structure of the sample with a low area ratio of the fibrous structure has a thick recrystallized structure formed on the surface as compared with FIG. 1, and no fibrous pattern is seen. A layer (recrystallized structure) having a color tone different from that of the sample was clearly observed in the vicinity of the surface.

  Sample No. In No. 11, since the contents of Mn, Cr, and Zr were too large, the particle size of the crystallized product was excessively large, and peeling of the surface was observed after the extrusion process.

Sample No. In No. 12, since the Ti content was too small, the area ratio of the fibrous structure was low, and as a result, the yield strength was low and it was determined to be unacceptable.
Sample No. In No. 13, since each content of Ti, V, and Fe was too large, the particle size of the crystallized product was excessively large, and peeling of the surface was recognized after the extrusion process, and it was determined to be rejected.

(Example 2)
This example is an example in which a method for producing the high-strength aluminum alloy extruded material was examined. In this example, the alloy no. Using A, the production conditions were changed as shown in Table 4 to prepare samples (Sample Nos. 21 to 39), and the strength measurement, metal structure observation, surface quality evaluation, and corrosion resistance evaluation of each sample were performed. The details of the manufacturing conditions and strength measurement method, metal structure observation method, surface quality evaluation method, and corrosion resistance evaluation method of each sample are the same as in Example 1.

  The evaluation results for each sample are shown in Table 5. In addition, about what was not determined to be acceptable or not preferable in each evaluation result, the evaluation result in Table 5 is underlined.

  As known from Table 5, sample no. 21-No. No. 30 passed in all evaluation items, and exhibited excellent properties in all of strength, corrosion resistance, extrusion processability and surface quality.

Sample No. No. 31 had a low proof stress because the holding temperature in the homogenization treatment was too low, and peeling of the surface was recognized after extrusion, and it was determined to be unacceptable.
Sample No. No. 32 was judged to be unacceptable because the holding temperature in the homogenization treatment was too high, resulting in a decrease in the area ratio of the fibrous structure, resulting in a decrease in yield strength.

  Sample No. No. 33 was judged to be unacceptable because the holding time in the homogenization treatment was too short, so that the proof stress was low, and surface exfoliation was observed after extrusion.

Sample No. No. 34 determined that the proof stress was unacceptable because the ingot temperature before hot extrusion was too low.
Sample No. In 35, since the ingot temperature before hot extrusion was too high, peeling of the surface was recognized after extrusion, and it was determined to be unacceptable.

  Sample No. No. 36 determined that the yield strength was unacceptable because the cooling rate in the rapid cooling treatment was too small.

  Sample No. In No. 37, the temperature of the extruded material after completion of the rapid cooling treatment was too high, so the proof stress was determined to be unacceptable.

  Sample No. 38 and no. No. 39 was determined to have failed proof stress because the treatment time and treatment temperature in the aging treatment were outside the above specific range.

Claims (3)

Si: 0.70 to 1.3% (mass%, the same applies hereinafter), Mg: 0.45 to 1.2%, Cu: 0.15 to less than 0.40%, Mn: 0.10 to 0.40 %, Cr: 0.06% or less (excluding 0%), Zr: 0.05 to 0.20%, Ti: 0.005 to 0.15%, Fe: 0.30% or less, V: restricted to 0.01% or less, having a chemical component consisting of the balance Al and inevitable impurities,
The crystallized particle size is regulated to 5 μm or less,
A high-strength aluminum alloy extruded material, wherein the area ratio of the fibrous structure in a cross section parallel to the hot extrusion direction is 95% or more.   The high-strength aluminum alloy extruded material according to claim 1, wherein the high-strength aluminum alloy extruded material is used as a structural member for a vehicle. Si: 0.70 to 1.3% (mass%, the same applies hereinafter), Mg: 0.45 to 1.2%, Cu: 0.15 to less than 0.40%, Mn: 0.10 to 0.40 %, Cr: 0.06% or less (excluding 0%), Zr: 0.05 to 0.20%, Ti: 0.005 to 0.15%, Fe: 0.30% or less, V: Restricted to 0.01% or less, producing an ingot having a chemical component composed of the balance Al and inevitable impurities,
A homogenization treatment is performed in which the ingot is held at a temperature of 450 ° C. or higher and lower than 500 ° C. for 2 to 30 hours,
Then, in the state where the temperature of the ingot at the start of processing is 480 ° C. to 540 ° C., the ingot is subjected to hot extrusion to obtain an extruded material,
While the temperature of the extruded material is 480 ° C. or higher, it is rapidly cooled to 150 ° C. or lower at a cooling rate of 2 to 100 ° C./second,
Then, the manufacturing method of the high-strength aluminum alloy extrusion material characterized by performing the aging treatment which heats the said extrusion material at the temperature of 150 to 200 degreeC for 1 to 24 hours.