WO2017126413A1

WO2017126413A1 - Machine component, method for producing same, and extruded material

Info

Publication number: WO2017126413A1
Application number: PCT/JP2017/000868
Authority: WO
Inventors: 康博有賀; 琢哉高知; 孝太郎豊武
Original assignee: 株式会社神戸製鋼所; 神鋼メタルプロダクツ株式会社
Priority date: 2016-01-21
Filing date: 2017-01-12
Publication date: 2017-07-27

Abstract

Provided is a machine component which has a 7000 series aluminum alloy extruded structure that contains, in terms of mass%, 8.0-14.0% of Zn, 2.0-4.0% of Mg, 0.5-2.0% of Cu, 0.2-1.5% of Mn and 0.05-0.3% of Zr, with the remainder comprising Al and unavoidable impurities, and which is characterized in that the structure and characteristics as determined by measuring a surface parallel to the extrusion direction at an intermediate position between a surface and the central axis of the machine component using a SEM-EBSD method are such that the average proportion of small angle grain boundaries having angles of 5-15° is 5% or more, the average proportion of large angle grain boundaries having angles of greater than 15° is 20% or more, the average KAM value is 0.3° or more, the tensile strength is 800 MPa or more and the total elongation is 5% or more. Also provided is a method for producing the machine component, and an extruded material able to produce the machine component.

Description

Machine parts, manufacturing method thereof, extruded material

The present invention relates to a machine part, a manufacturing method thereof, and an extruded material. The mechanical parts referred to in the present invention are various machines such as screw parts such as bolts and nuts, gears (shafts), bearings (bearings), springs (springs), etc., made of extruded material. It is a machine element as a functional unit of the smallest unit that is commonly used.

Conventionally, Al-Zn-Mg-Cu-based materials (materials) with excellent strength, corrosion resistance and light weight as materials for various machine parts such as bolts and nuts and springs (springs). A linear or rod-like extruded material made of a certain 7000 series aluminum alloy and having a circular cross section is used.

The extruded material made of the 7000 series aluminum alloy has high strength, and various types of materials having a tensile strength of 700 MPa or more have been conventionally proposed by tempering T6 after extrusion.

For example, Patent Document 1 discloses that a 7000 series aluminum alloy wire rod extruded material having a Zn content exceeding 8 mass% can be easily imparted with a strength exceeding a tensile strength of 720 MPa by aging treatment. However, in the extruded material according to the same document, a coarse recrystallized grain layer is inevitably generated, so that cracking occurs when the extruded material is subjected to plastic working (forming processing) such as forging or rolling into a large-diameter bolt. Cause. For this reason, it is essential to remove the coarse recrystallized grain layer on the surface of the extruded material (surface layer portion) before plastic working.

In contrast, various attempts to suppress such a recrystallized grain layer have been proposed. For example, in Patent Document 2, the extrusion temperature is set to a relatively low temperature of 480 to 500 ° C., the inside of the extruded 7000 series aluminum alloy is made into a fibrous structure, the thickness of the recrystallized layer on the surface layer is set to 10% or less, and the recrystallization is performed. It is disclosed that the particle size is controlled to 150 μm or less.
However, even if the extrusion temperature is set to a relatively low temperature of 480 to 500 ° C. as in Patent Document 2, the 7000 series aluminum alloy is also recrystallized by extrusion in this temperature range. Therefore, recrystallization in the surface layer portion and inside of the extruded material is unavoidable, and there is a possibility that a strength of 700 MPa or more cannot be obtained with good reproducibility.

Patent Document 3 discloses manufacturing a 7000 series aluminum alloy extruded material by hot isostatic pressing. In the extruded material, the average crystal grain size of the recrystallized grains in the surface layer portion of the extruded material is 100 μm or less as a cross-sectional structure parallel to the extrusion direction passing through the axial center portion of the extruded material in the extruded state. In addition, the average intercept length in the radial direction of the crystal grains in the central portion of the extruded material axis is 35 μm or less, and the average area ratio of the <111> orientation crystal grains in the extrusion direction is 0.5 or more and 1.0 or less. Thus, it is disclosed that the ratio <001> / <111> between the average area ratio of <001> oriented crystal grains and the average area ratio of <111> oriented crystal grains is 0.25 or less.
In Patent Document 3, after this, after the hot extrusion is finished, except for cooling from the extrusion temperature, no heat treatment or processing that changes the structure is applied. As a result, not only the surface layer portion but also recrystallization (recrystallization) inside the extruded material is suppressed. Thus, it is disclosed that a fine extruded structure (fibrous structure) is obtained and a high strength of 700 MPa or more is obtained as a tensile strength after artificial aging treatment.
However, in Patent Document 3, as shown in Table 3 of the examples, the obtained tensile strength after the artificial aging treatment is 700 MPa or more, but is less than about 800 MPa.

Patent Document 4 discloses a 7000 series aluminum alloy rolled plate for automobile structural members such as frames and pillars, not extruded materials. In this document, in order to increase the strength, as the crystal orientation structure of this rolled sheet, the average crystal grain size is 15 μm or less, and the average proportion of low-angle grain boundaries with an inclination of 5 to 15 ° is 15% or more, and It is disclosed that the average proportion of large-angle grain boundaries exceeding 15 ° is 15 to 50%.
However, in the case of this Patent Document 4, as shown in Table 2 of Examples, the obtained tensile strength after artificial aging treatment is less than 500 MPa, and such a metallurgical method using a rolled sheet is a plastic working method and Whether the manufacturing method is effective for increasing the strength of 800 MPa or more of extruded materials and machine parts that are different from each other must be actually tested to confirm.

JP 2010-236665 A Japanese Patent No. 2908993 JP 2014-125676 A JP 2014-62287 A

Thus, the conventional 7000 series aluminum alloy extruded material, as a material for the machine parts or machine elements, without increasing the amount of alloy and reducing the corrosion resistance such as SCC resistance and intergranular corrosion resistance, It was difficult to stably obtain a high strength of 800 MPa or more as the mechanical component after the artificial aging treatment.

The present invention has been made in view of such a problem, and the mechanical part is made of a 7000 series aluminum alloy extruded material that has a high strength characteristic in which a tensile strength after artificial aging treatment is 800 MPa or more and a total elongation is 5% or more. Another object of the present invention is to provide a method for producing the same and an extruded material.

In order to achieve the above object, the gist of the mechanical parts having excellent strength of the present invention is mass%, Zn: 8.0 to 14.0%, Mg: 2.0 to 4.0%, Cu: 0 Extrusion of 7000 series aluminum alloy containing 0.5 to 2.0%, Mn: 0.2 to 1.5%, Zr: 0.05 to 0.3%, the balance being Al and inevitable impurities A machine part having a structure, and a plane parallel to the extrusion direction at an intermediate position between the surface of the machine part and the axis center, and the structure and characteristics measured by the SEM-EBSD method, have an inclination angle of 5 to 15 °. The average ratio of small-angle grain boundaries is 5% or more, the average ratio of large-angle grain boundaries exceeding 15 ° is 20% or more, the average KAM value is 0.3 ° or more, and the tensile strength is Suppose that it is 800 MPa or more and the total elongation is 5% or more.

Further, the gist of the method of manufacturing the mechanical component of the present invention for achieving the above object is mass%, Zn: 8.0 to 14.0%, Mg: 2.0 to 4.0%, Cu: 0 A 7000 series aluminum alloy ingot containing 0.5 to 2.0%, Mn: 0.2 to 1.5%, Zr: 0.05 to 0.3%, the balance being Al and inevitable impurities After the soaking process, the extruded material is processed into an extruded material. After the extruded material is processed into a machine part, solution treatment and quenching are performed, and further artificial aging is performed. As the structure and characteristics of the surface parallel to the extrusion direction at the position measured by the SEM-EBSD method, the average proportion of the small-angle grain boundaries with an inclination of 5 to 15 ° is 5% or more, and the large-angle grains with an inclination of more than 15 ° Average ratio of 20% or more and average KAM value The structure is such that the value is 0.3 ° or more, the tensile strength of this machine part is 800 MPa or more, and the total elongation is 5% or more.

Furthermore, the gist of the extruded material of the present invention for achieving the above object is mass%, Zn: 8.0 to 14.0%, Mg: 2.0 to 4.0%, Cu: 0.5 to Extruded material for mechanical parts of 7000 series aluminum alloy containing 2.0%, Mn: 0.2 to 1.5%, Zr: 0.05 to 0.3%, the balance being Al and inevitable impurities The extruded material was a wire rod extruded material with a diameter of 25 mm having a circular cross-section, simulating a machine part, and drawn by a reduction in area of 84%, and a cross-section of 10 mmφ was circular. After the solution treatment in which the wire rod is held at a temperature of 480 ° C. for 5 hours, the wire rod is quenched at an average cooling rate of up to 50 ° C. at 200 ° C./second, and then held at 120 ° C. for 72 hours. The extrusion at an intermediate position between the surface of the wire rod and the axis center when the aging treatment is performed. As the structure and characteristics of the surface parallel to the working direction measured by the SEM-EBSD method, the average ratio of the small-angle grain boundaries with an inclination of 5 to 15 ° is 5% or more, and the average ratio of the large-angle grains with an inclination of more than 15 ° is The average KAM value is 0.3 ° or more, the tensile strength is 800 MPa or more, and the total elongation is 5% or more.

The present invention provides a crystal grain structure (crystal grain) measured by the SEM-EBSD method after artificial aging treatment as the mechanical part made of 7000 series aluminum alloy extruded material, that is, a mechanical part having an extruded microstructure of aluminum alloy. The average ratio between the low-angle grain boundaries and the large-angle grain boundaries and the KAM value that is the average orientation difference are controlled.
In addition, the crystal structure (crystal grains) measured by the SEM-EBSD method when a specific drawing process, solution treatment, and artificial aging process of the extruded material (raw material) simulating the mechanical parts were performed. The average ratio between the low-angle grain boundaries and the large-angle grain boundaries and the KAM value that is the average orientation difference are controlled.
The term “after artificial aging treatment” in the present disclosure means “after solution treatment and quenching treatment and artificial aging treatment”.
As a result, it is possible to achieve high strength with a tensile strength of 800 MPa or more and a total elongation of 5% or more as the characteristics of the machine parts or the characteristics of the extruded material simulating the machine parts.
In addition, such a structure control of the present disclosure has an advantage that the strength can be increased without fear of lowering the corrosion resistance such as SCC resistance and intergranular corrosion resistance of mechanical parts.
Furthermore, if the recrystallized grain layer in the surface layer portion (surface portion) of the extruded material can be suppressed, there is an advantage that the product shape of the mechanical part can be processed without removing the recrystallized grain layer in the surface layer portion of the extruded material.

Hereinafter, embodiments of the present invention will be specifically described in order for each requirement.
The aluminum alloy composition and structure described below will be described with respect to the common significance and individual significance as mechanical parts or extruded materials.
In addition, the extrusion material (material) for machine parts which concerns on embodiment of this invention is a linear or rod-shaped extrusion material, The cross-sectional shape has prescribed | regulated that the cross-sectional shape is circular in embodiment of this invention. . The circular shape of the cross-sectional shape means a perfect circle. On the other hand, the embodiment of the present invention may be an ellipse or a circle whose outermost diameter is a circle. Some have a close cross-sectional shape.

1.7000 series aluminum alloy composition:
The 7000 series aluminum alloy composition according to the embodiment of the present invention is an average of a small-angle grain boundary and a large-angle grain boundary for each structure of a machine part after artificial aging treatment or a material extruded material simulating this machine part. This is a precondition for controlling the ratio and the KAM value, which is the average azimuth difference, within a specified range. At the same time, it is a precondition for the tensile strength to be 800 MPa or more and the total elongation to be 5% or more as a machine part or extruded material after artificial aging treatment.

For this purpose, the composition of the 7000 series aluminum alloy is, by mass, Zn: 8.0 to 14.0%, Mg: 2.0 to 4.0%, Cu: 0.5 to 2.0%, Mn: 0 .2 to 1.5%, Zr: 0.05 to 0.3%, respectively, with the balance being Al and inevitable impurities. This composition may further contain one or two of Cr: 0.05 to 0.3% and Sc: 0.05 to 0.3% by mass%.
Further, the above composition may further contain one or two of Ag: 0.01 to 0.2% and Sn: 0.01 to 0.2% by mass%. .
Here, the% display of the content of each element means the mass%, including the content of each element described below.

(1) Zn: 8.0 to 14.0%
Zn, which is an essential alloy element, improves the strength together with Mg by forming an aging precipitate that is an intermetallic compound of Mg and Zn during an artificial aging treatment described later. If the Zn content is less than 8.0%, the strength as a mechanical part is insufficient, and if it exceeds 14.0%, ingot cracking is likely to occur during casting of the cast billet for the material extrusion material, and ingot formation is difficult. Become.
Therefore, the Zn content is in the range of 8.0 to 14.0%, preferably in the range of 8.0 to 13.0%. In addition, when Zn content is high, SCC sensitivity becomes sharp, but in order to suppress it, it is desirable to add Cu or Ag described later.

(2) Mg: 2.0 to 4.0%
Mg, which is an essential alloying element, together with Zn, forms an aging precipitate that is an intermetallic compound of Mg and Zn as defined in the embodiment of the present invention during the artificial aging treatment described later, and provides strength as a mechanical component. Increase elongation. If the Mg content is less than 2.0%, the strength is insufficient, and if it exceeds 4.0%, the cast billet for the extruded material is extruded at a low temperature in the non-recrystallization temperature range (temperature range below the recrystallization temperature). Sexuality is reduced and SCC sensitivity is increased. Therefore, the Mg content is in the range of 2.0 to 4.0%, preferably in the range of 2.5 to 3.5%.

(3) Cu: 0.5 to 2.0%
Cu has the effect of improving the SCC resistance as a machine part. When the Cu content is less than 0.5%, the effect of improving the SCC resistance is small. On the other hand, if the Cu content exceeds 2.0%, cracks during casting of the cast billet for the raw material extrudate lower the extrudability at a low temperature lower than the recrystallization temperature of the cast billet. Therefore, the Cu content is in the range of 0.5 to 2.0%, preferably in the range of 0.7 to 1.8%.

(4) Mn: 0.2 to 1.5%
In addition to refining crystal grains, Mn contributes to improving the strength of mechanical parts by forming dispersed particles. If the Mn content is less than 0.2%, the content is insufficient and the strength decreases. On the other hand, if the Mn content exceeds 1.5%, a coarse crystallized product is formed, resulting in a decrease in elongation. Therefore, the Mn content is in the range of 0.2 to 1.5%, preferably in the range of 0.3 to 1.2%.

(5) Zr: 0.05 to 0.3%
Zr forms fine precipitates, suppresses recrystallization, and contributes to improving the strength of machine parts. If the content of Zr is less than the lower limit, the content is insufficient and the strength is lowered. On the other hand, when the content of Zr exceeds the upper limit, a coarse crystallized product is formed, so that the elongation decreases. Therefore, Zr is in the range of 0.05 to 0.3%, preferably Zr: in the range of 0.1 to 0.25%.

The mechanical component and the extruded material according to the embodiment of the present invention are not limited to the above-described composition. As long as the characteristics of the machine part and the extruded material according to the embodiment of the present invention can be maintained, other elements may be further included as necessary. Other elements that can be selectively contained as described above are exemplified below.

(6) One or two of Cr: 0.05 to 0.3% and Sc: 0.02 to 0.5% Cr and Sc, like Zr, form fine precipitates and are recrystallized. This also helps to improve the strength of machine parts. When either one or two of these are selectively contained, if the contents of Cr and Sc are both less than the lower limit, the strength improving effect may be lowered. On the other hand, when the contents of Cr and Sc exceed the respective upper limits, a coarse crystallized product is formed, so that the elongation may decrease. Accordingly, Cr is preferably in the range of 0.05 to 0.3% and Sc is in the range of 0.02 to 0.5%, more preferably 0.1 to 0.25% for Cr and 0. Each range is from 05 to 0.4%.

(7) One or two of Ag: 0.01 to 0.6% and Sn: 0.01 to 0.2% Ag and Sn are precipitate-free zones in the vicinity of the grain boundaries in the artificial aging treatment. Suppresses formation and contributes to improving the strength of machine parts When it is selectively contained, if the contents of Ag and Sn are each less than 0.01%, the effect of miniaturization may be small. On the other hand, if the content of Ag and Sn exceeds 0.6% and 0.2%, respectively, a coarse primary crystal compound is formed at the time of casting the cast billet for the raw material extruded material, and baking at the time of extrusion processing, May reduce the elongation of machine parts as a product. Therefore, the Ag content is preferably 0.6% or less, more preferably 0.5% or less, and further preferably 0.2% or less. The Sn content is preferably 0.2% or less, and more preferably 0.15% or less.

(8) Ti, B:
Ti and B are unavoidable impurities, but have the effect of refining the crystal grains of the aluminum alloy ingot, so that each of them is allowed as a 7000 series alloy within the range specified by the JIS standard.

(9) Other elements:
Other elements other than those described above, such as Fe and Si, are unavoidable impurities. As a melting raw material, in addition to pure aluminum ingots, the inclusion of these impurity elements due to the use of aluminum alloy scrap is assumed (allowed), and each content within the range specified by the JIS standard of 7000 series alloys is allowed. . For example, Fe and Si may each be contained within a range of 0.5% by mass or less (including 0%).

2. Organization:
Since the mechanical component according to the embodiment of the present invention is made of an extruded material, the structure is inevitably an extruded microstructure of a 7000 series aluminum alloy, and fine nano-sized precipitates are present. Many exist in the crystal grains to achieve high strength.
This precipitate is an intermetallic compound of Mg and Zn (composition is MgZn ₂ or the like) that is generated in the crystal grains, and further contains elements such as Cu and Zr depending on other alloy compositions. It is a finely dispersed phase.

In the embodiment of the present invention, in order to further increase the strength and ensure the elongation, as the extruded microstructure after the artificial aging treatment of the machine part, a small-angle grain boundary and a large-angle grain measured by the SEM-EBSD method are used. The average ratio of the field and the KAM value that is the average azimuth difference are further controlled. In addition, the grain structure (crystal) measured by the SEM-EBSD method of a machine part extruded material (raw material) when subjected to specific drawing, solution treatment, and artificial aging treatment simulating this machine part. Grain) and the KAM value which is the average misorientation.

That is, the surface of the mechanical part of the mechanical part manufactured by cold working the material 7000 series aluminum alloy extruded material, or the structure after the artificial aging treatment, or the extruded material (material) simulating this mechanical part A plane parallel to the extrusion direction at an intermediate position between the center and the axis is defined as the structure measured by the SEM-EBSD method.
Specifically, the average ratio of small-angle grain boundaries with an inclination angle of 5 to 15 ° is 5% or more, the average ratio of large-angle grain boundaries with an inclination angle of 15 ° is 20% or more, and the average KAM value is 0. .3 ° or more.

The structure and mechanical properties of the mechanical part after the artificial aging treatment are as follows: The raw material extruded material is actually rolled or forged into a mechanical part, and the artificial aging treatment is not performed. It can be evaluated by examining the structure and mechanical properties after adding drawing, solution treatment, and artificial aging treatment that simulates mechanical parts.
As a preferable processing condition for simulating this machine part, a wire rod extruded from a material wire rod having a circular cross section of 20 to 50 mm in diameter and having a surface area reduction of 80 to 90% up to drawing is used. After solution treatment that is held at a temperature of 500 ° C. for 0.5 to 10 hours, an quenching treatment is performed at an average cooling rate up to 50 ° C. at 50 ° C./second or more, and then an artificial temperature that is held at 100 to 200 ° C. for 2 to 120 hours By examining the structure and mechanical characteristics when the aging treatment is performed, the correlation with the actual machine parts is high, and the evaluation can be performed with good reproducibility.
However, in order to make this reproducibility more strict, as specified in claim 6, specific processing conditions for simulating a machine part are used, and the extruded material is a wire rod extruded material having a circular section of 25 mm in diameter. In addition, a wire rod material having a reduction in area of 84% and drawn into a wire rod having a 10 mmφ cross-section is rounded. After solution treatment in which the wire rod material is held at a temperature of 480 ° C. for 5 hours, More preferably, the quenching treatment is performed at an average cooling rate of 200 ° C./second, and then an artificial aging treatment is performed at 120 ° C. for 72 hours, and then a one-point condition is set.
Note that the drawing area reduction ratio is defined as follows. When the cross-sectional area of the original extruded material is A and the cross-sectional area of the wire rod after drawing is a, the reduced area (AA) is the original area A. (A−a) × 100 / A (%) divided by.

In this way, there are more than a certain percentage of low-angle grain boundaries, and the average ratio between the small-angle grain boundaries and the large-angle grain boundaries mixed with a certain percentage of large-angle grain boundaries, and the KAM value that is the average misorientation are specified. By making the finely processed structure within the range of (2), it is possible to make the material uniformly deformed without locally concentrating the strain in the deformation process of the material of the machine part.

As a result, local breakage of the machine parts can be prevented, and the tensile strength can be as high as 800 MPa or more, and an elongation of 5% or more can be secured. That is, as a characteristic of the mechanical part after the artificial aging treatment or as a characteristic after the artificial aging treatment of the aluminum alloy extruded material simulating the mechanical part, the tensile strength can be 800 MPa or more and the total elongation can be 5% or more. .
In such structure control according to the embodiment of the present invention, there is no fear that the corrosion resistance such as SCC resistance and intergranular corrosion resistance of mechanical parts will be lowered, and the strength can be increased.

Lacking these requirements, as the structure after the artificial aging treatment, if the average proportion of the small-angle grain boundaries with an inclination angle of 5 to 15 ° is less than 5%, the KAM, for example, KAM Even if the value is satisfied, characteristics with a tensile strength of 800 MPa or more cannot be obtained. Further, when the average ratio of the large tilt grain boundaries is less than 20%, the elongation is lowered even if the KAM value is satisfied.

Further, as the structure after the artificial aging treatment, it is difficult to increase the strength even if the average value of the KAM value of the extruded material simulating the use of the machine part or the machine part is less than 0.3 °.
The specific action and effect of the KAM value itself is unknown, but by setting the average value of the KAM value to 0.3 ° or more, the effect of hindering the dislocation movement of the machine parts is remarkably increased, and the balance between strength and ductility is increased. It is speculated that may improve.
Therefore, if the average value of the KAM value is less than 0.3 °, even if the average ratio of both the low-angle grain boundary and the large-angle grain boundary is satisfied, the tensile strength is still 800 MPa or more and the total elongation is However, a characteristic of 5% or more cannot be obtained.

(Definition of low-angle and high-angle grain boundaries)
The small-angle grain boundary referred to in the embodiment of the present invention is a grain boundary between crystal grains having a small crystal orientation difference (tilt angle) of 5 to 15 ° among crystal orientations measured by the SEM-EBSD method described later. is there. In addition, the large tilt grain boundary referred to in the embodiment of the present invention is a grain boundary between crystal grains in which the difference in crystal orientation (tilt angle) exceeds 15 ° and is 180 ° or less.
Here, the proportion of crystal grain boundaries with an orientation difference of less than 5 ° is greatly influenced by the preparation conditions (surface state) of the sample to be subjected to the measurement, and on the contrary, it is a disturbance, so it is not considered in the embodiment of the present invention. not regulated. Therefore, the crystal grain boundary having an orientation difference of less than 5 °, the small-angle grain boundary, and the large-angle grain boundary are combined, and the ratio becomes 100%.
In the embodiment of the present invention, as the average ratio of the small tilt grain boundaries, the total length of the crystal grain boundaries of the measured small tilt grain boundaries (the total length of the crystal grain boundaries of all the small tilt grain grains) is the same. The ratio of the measured crystal orientation difference (orientation difference) to the total length of the crystal grain boundary of 2 to 180 ° (the total length of all the measured crystal grain boundaries) is small with an inclination of 5 to 15 °. It is defined as the ratio of tilt grain boundaries. That is, the ratio (%) of the low-angle grain boundary having an inclination angle of 5 to 15 ° is defined as [(total length of crystal grain boundary of 5 to 15 °) / (full length of crystal grain boundary of 2 to 180 °)] × 100 The average of this value is 5% or more. From the production limit, the upper limit of the ratio of the low-angle grain boundaries of 5 to 15 ° is about 50%.

On the other hand, the average ratio of the large tilt grain boundary is also the same as the total crystal grain boundary of the measured large tilt grain boundary (the total length of the measured grain boundaries of all the small tilt grain). The ratio of the orientation difference to the total length of the grain boundaries having a difference of 2 to 180 ° (the total length of the measured crystal grain boundaries of all crystal grains) is defined as the ratio of the large tilt grain boundaries exceeding the tilt angle of 15 °. That is, the ratio (%) of the specified large-angle grain boundary can be calculated as [(total length of crystal grain boundary of more than 15 ° and 180 ° or less) / (full length of crystal grain boundary of 2 to 180 °)] × 100. The average of these values is 20% or more. The ratio of large-angle grain boundaries can be increased to over 90%. In this application, the ratio of small-angle grain boundaries with an inclination angle of 5 to 15 ° is set to 5% or more. The upper limit is 95%.

(Definition of KAM value)
The KAM value is an abbreviation for Kernel Average Missoration value, and is an average orientation difference of crystal grain structures (crystal grains) measured by the SEM-EBSD method.
The KAM value itself is known to correlate with the residual strain, for example, “Materials” (Journal of the Society of Materials Science, Japan) Vol. 58, No. 7, P568-574, July 2009, etc. . It is also known that the KAM value is a value obtained by quantifying a local orientation difference, which is a difference in crystal orientation between adjacent measurement points, as an average orientation difference.
Furthermore, it is known that this KAM value is controlled to improve press formability and bending workability in the field of copper alloy sheets and steel sheets other than aluminum alloys. However, the relationship between the average KAM value and the aminium alloy characteristics has not been known so far, and the press formability and bending workability, which are the purposes of KAM value control in the field of the copper alloy plate and steel plate, The mechanism of the present invention is greatly different from that of the high strength and high ductility properties.

3. Tissue measurement:
The above measurement of the structure is performed by SEM-EBSD method using a surface (cross section) parallel to the extrusion direction at the intermediate position between the surface of the machine part or the extruded material and the axis center thereof as an observation surface. .
The reason why the plane (cross section) parallel to the extrusion direction is the observation plane is to measure the crystal orientation in the longitudinal direction (extrusion direction) of the crystal grains that are the extrusion structure by the SEM-EBSD method.
Thereby, as the structure after mechanical aging treatment of the machine part and the aluminum alloy extruded material, the average ratio of the small-angle grain boundary and the large-angle grain boundary and the KAM value that is the average orientation difference can be measured.

The sample is taken from the above-described cross section of the machine part or the extruded material so that the measurement range (area) is 600 μm in the direction parallel to the extrusion direction and 400 μm in the direction perpendicular to the measurement direction. The measurement is performed on five samples collected from arbitrary five places, and these are averaged.

The SEM-EBSD (EBSP) method is a crystal orientation analysis in which a field emission scanning electron microscope (FESEM) is equipped with an electron back scattering (Scattered) diffraction pattern (EBSD) system. Is the law.
More specifically, the observation sample of SEM-EBSD is prepared by mirror-polishing the observation sample (cross-sectional structure) after further mechanical polishing. Then, the EBSP is set on the FESEM column and irradiated with an electron beam onto the mirror-finished surface of the sample to project EBSP on the screen. This is taken with a high-sensitivity camera and captured as an image on a computer. In the computer, the orientation of the crystal is determined by analyzing this image and comparing it with a pattern obtained by simulation using a known crystal system. The calculated crystal orientation is recorded as a three-dimensional Euler angle together with position coordinates (x, y, z) and the like. Since this process is automatically performed for all measurement points, tens of thousands to hundreds of thousands of crystal orientation data on the observation surface can be obtained at the end of measurement.

In these crystal analyses, the Kikuchi line is generated by electron beam backscatter diffraction that occurs on the surface of the material while scanning by irradiating the material with an electron beam in combination with SEM, using a crystal analysis method based on the electron channeling pattern method (ECP method). A diffraction pattern, that is, an EBSD pattern is measured and analyzed. Details of the crystal orientation analysis method in which the EBSD system is mounted on these FESEMs are described in detail in Kobe Steel Engineering Reports / Vol.52 No.2 (Sep.2002) P66-70.

Thus, by measuring and analyzing the structure of the machine part or the extruded material, information on the crystal grain size, the section length of the crystal grain in the radial direction, and the crystal orientation can be obtained in the minute region of each part. That is, it is possible to measure and analyze the average ratio of the low-angle grain boundary and the large-angle grain boundary and the KAM value that is the average orientation difference.

4). Measurement of KAM value:
When measuring the KAM value, for the reproducibility of the measurement by the SEM-EBSD method, the positional relationship between the reference pixel for calculating the KAM value and the adjacent pixel is within the region up to the nth proximity. It is necessary to set whether to calculate all pixels, and the setting is made up to the first proximity in the embodiment of the present invention.
As for the setting in the analysis software, the setting of the neighbor (Nearest Neighbor) is set to 1st. Further, in the embodiment of the present invention, with respect to the KAM value obtained for each reference pixel, the upper limit of the maximum azimuth difference is set to 5 °, and only the pixel data having a KAM value within 5 ° is used. The average KAM value within the analysis range was calculated. In the setting with the analysis software, the maximum misorientation was set to 5 °.

5). Production method:
The preferable manufacturing method of the extrusion material and machine part which concern on embodiment of this invention is demonstrated.

5-1. First, a preferred method for producing an extruded material (extruded profile) will be described. As will be described below, the extruded material according to the embodiment of the present invention is subjected to hydrostatic extrusion at a low extrusion temperature in an unfinished crystal region after performing melting / casting and homogenization heat treatment conditions under appropriate conditions. Can be obtained. As in the extruded material according to the embodiment of the present invention, in a 7000 series Al alloy having a high content of Zn of 8% by mass or more, in a normal extrusion method such as direct extrusion or indirect extrusion, Since seizure occurs due to friction with the die, extrusion processing cannot be performed at a temperature lower than the recrystallization temperature range, and an extruded material having a fine processed structure cannot be obtained. In the manufacturing method according to the embodiment of the present invention, since hot extrusion is performed by hydrostatic extrusion, the extrusion process can be performed at a temperature lower than the recrystallization temperature range even with a high Zn content of 8% by mass or more. And an extruded material having a fine processed structure can be obtained. Then, by using the extruded material having such a high Zn content and a fine processed structure, a mechanical component having high tensile strength and total elongation is obtained by manufacturing the mechanical component under the conditions described later. Can do. Below, the manufacturing method of the extrusion material which concerns on embodiment of this invention is demonstrated in order of a process.

(1) Melting / Casting First, in the melting / casting process, a normal melt casting method such as a semi-continuous casting method (DC casting method) is appropriately selected for the aluminum alloy melt adjusted within the above 7000 series component composition range. And cast into billets.

(2) Homogenization heat treatment Prior to hot extrusion, the cast aluminum alloy billet (ingot) is subjected to homogenization heat treatment (uniform heat treatment) to homogenize the structure (segregation in crystal grains in the ingot structure). Etc.). By controlling the soaking temperature at 400 to 450 ° C., the Zr-based compound and the compound composed of Mn, Cr, and Sc are finely dispersed, and the crystal grain structure after extrusion and solution treatment is refined. If it is less than 400 ° C., a sufficient effect of miniaturization cannot be obtained. If it exceeds 450 ° C., these compounds are coarsened, so the effect of miniaturization is reduced. In addition, the standard holding time during soaking is about 1 to 8 hours.

(3) Hot extrusion By hot extrusion, an extruded material shape close to this final shape corresponding to the final machine part shape is obtained.
At this time, in order to suppress not only the surface layer portion of the extruded material but also recrystallization inside the extruded material to form a finely processed structure, the non-recrystallized region below the recrystallization temperature is in the range of 300 to 400 ° C. Extrusion is preferably performed at a low extrusion temperature (the extrusion start temperature of the billet and the temperature during the extrusion process). By setting the extrusion temperature in the range of 300 to 400 ° C., not only the surface layer portion of the extruded material but also the internal recrystallization can be suppressed, and a fine extruded structure can be obtained.

When this extrusion temperature exceeds 400 ° C., the temperature during extrusion rises and recrystallization easily occurs at a high temperature, and a coarse recrystallized structure is formed on the surface layer portion and inside of the extruded material, resulting in deterioration of corrosion resistance and strength. Bring about a decline. On the other hand, the lower the extrusion temperature, the better. However, since the deformation resistance increases on the low temperature side and extrusion becomes difficult, the lower limit is about 300 ° C. The temperature is preferably 320 to 380 ° C.

Further, the extrusion speed is preferably 10 m / min or less in order to suppress processing heat generated during extrusion and suppress the recrystallization during extrusion. More preferably, it is 7 m / min or less.
The cooling after the hot extrusion is not limited regardless of the means and cooling rate including cooling, but it is preferable to forcibly cool by air from the efficiency of the extrusion process.

(Extrusion method)
As an extrusion method, it is carried out by isostatic extrusion under the preferable extrusion conditions in the non-recrystallized region.
When the extrusion method is direct extrusion or indirect extrusion, it is more efficient than hydrostatic extrusion, but the recrystallized grain layer on the surface of the extruded material (surface) is relatively fine in the extrusion direction. There is a problem in that it tends to be a coarse grained crystal grain as compared with an elongated fibrous crystal grain (extruded) structure. Further, in the case of extruding a 7000 series aluminum alloy having a Zn content exceeding 8% as in the embodiment of the present invention, in the case of direct extrusion or indirect extrusion, an extrusion process below the recrystallization temperature range. Is quite difficult.
This is because, even if the billet, which is an extrusion material, has a heating temperature lower than the recrystallization temperature range, in the case of direct extrusion or indirect extrusion, the billet is extruded in contact with the container wall surface and the die due to the structure of the extruder. As a result, frictional heat is generated, and as a result, the temperature during extrusion inevitably falls within the recrystallization temperature range. Therefore, inevitably, a coarse recrystallized (grain) layer that causes a problem in Patent Document 1 itself is easily formed on the surface layer portion of the extruded material.

On the other hand, in hot isostatic pressing, a lubricant is put between the container and the billet, and a state in which the billet for extrusion floats in this lubricant is pushed out by a stem (with a dummy block). . Thus, the billet is not in direct contact with the container and die due to the action of this lubricant, unlike direct and indirect extrusion. That is, the billet is in direct contact only while it passes through about 5 mm of the die thickness. As a result, friction and heat of friction are also reduced, and the metal flow becomes nearly uniform. As a result, even a billet of a 7000 series aluminum alloy as in the embodiment of the present invention having a high Zn content can be extruded even at a low temperature below the recrystallization temperature, and the surface layer portion and the inside of the extruded material It becomes possible to suppress (miniaturize) the recrystallized grain layer.
For this reason, the extruded material by hot isostatic pressing includes the recrystallized grain layer, or even if there is a recrystallized grain layer, the structure from the surface layer to the inside can be made uniform. As a result, the drawability, drawability, workability, and formability of the wire rod or wire rod product are significantly improved. In addition, if the recrystallized grain layer is suppressed as in the embodiment of the present invention, the basic characteristics such as sag resistance required for wire rod products such as aluminum alloy bolts by being a fine extruded structure. Can also be guaranteed.

5-2. Manufacturing method of machine part The extruded material after hot extrusion obtained as described above is further cold-worked into the product shape of the machine part for each application.

The general process for machined parts such as bolts of extruded materials is to draw and wash the extruded materials to reduce the diameter after annealing, and then anneal or roll or forge the product shape of the machine parts. And And after completion of such product processing, solution treatment and quenching treatment are performed, and further artificial aging treatment is performed to improve the strength.

Incidentally, the annealing is selective, and annealing may be performed during drawing or rolling. Further, the cold working such as drawing or rolling is, of course, concrete such as screw parts such as bolts and nuts, gears (gears), shafts (shafts), bearings (bearings), springs (springs), etc. The conditions are changed depending on the application and shape.

(1) Solution Treatment In the manufacturing method according to the embodiment of the present invention, the solution treatment of the machine part is held at a temperature of 450 ° C. or higher and 500 ° C. or lower for 0.5 to 10 hours. When the holding temperature is less than 450 ° C. or the holding time is less than 0.5 hour, the solid solution of Mg and Zn becomes insufficient and the strength is insufficient. And the average rate of a large inclination grain boundary will be less than 20%, and elongation will fall.
On the other hand, when the holding temperature exceeds 500 ° C. or the holding time exceeds 10 hours, the average proportion of the low-angle grain boundaries becomes less than 5%, and further, the average KAM value becomes small and the strength is insufficient.

(2) Quenching treatment In the manufacturing method according to the embodiment of the present invention, as a quenching treatment after the solution treatment, the cooling (cooling) rate from the solution treatment temperature to 50 ° C is 50 ° C / second or more on average. . If the average cooling rate is too low as less than 50 ° C./second, coarse recrystallization occurs, and the average ratio of the low-angle grain boundaries with an inclination of 5 to 15 ° is less than 5% in the structure after solution treatment. The average KAM value becomes small and the strength is insufficient. And coarse grain boundary precipitates that lower the strength and elongation are also formed, and the strength and total elongation are insufficient. The upper limit of the average cooling rate is about 500 ° C./second from the limit of the equipment capacity.
The cooling rate from 50 ° C. to room temperature is not particularly limited, and may be rapidly cooled as it is, or may be cooled by stopping the rapid cooling.

(3) Artificial aging treatment In the manufacturing method according to the embodiment of the present invention, conditions for artificial aging treatment of mechanical parts (or of extruded materials simulating mechanical parts) are set as general artificial aging of 7000 series aluminum alloy extruded materials. Compared to the processing conditions, there is an advantage that high strength can be achieved even as an aging treatment for a relatively short time.
In the manufacturing method according to the embodiment of the present invention, the artificial aging treatment at 100 to 200 ° C. is performed for 2 to 120 hours.
When the artificial aging treatment temperature exceeds 200 ° C, the recovery of the processed structure proceeds, so the average proportion of the low-angle grain boundaries with an inclination of 5 to 15 ° is less than 5%, the average of the KAM value is reduced, and the strength is reduced. To do.
On the other hand, even if the artificial aging time exceeds 120 hours, the recovery of the processed structure proceeds, so the average proportion of the low-angle grain boundaries with an inclination of 5 to 15 ° is less than 5%, and the average of the KAM value is reduced. , The strength decreases.

A person skilled in the art who is in contact with the characteristics of the mechanical parts and the extruded material according to the embodiment of the present invention described above and the manufacturing method thereof, will be able to perform the embodiment of the present invention by a manufacturing method different from the manufacturing method described above by trial and error. There is a possibility that a machine part and an extruded material according to the above can be obtained.

Hereinafter, the embodiments of the present invention will be described more specifically by way of examples. However, the present invention is not limited by the following examples, and may be appropriately changed within a range that can meet the purpose described above and below. It is also possible to implement by adding any of these, and they are all included in the technical scope of the present invention.

Next, examples of the present invention will be described. The present invention is not limited by the following examples, and can be implemented with modifications within a range that can be adapted to the above-described gist, which are all included in the technical scope of the present invention. Is done.

1. Sample preparation After casting a 7000 series aluminum alloy ingot having the composition shown in Table 1, it was subjected to soaking and hot isostatic extrusion, and in each example, a wire rod extrudate having a circular cross section and a diameter of 25 mm was produced. .
The extruding conditions of the wire rod extrudate are the same in each example, and after the soaking of the ingot at 430 ° C. for 5 hours, at the extrusion start temperature of the non-recrystallized region at 350 ° C. and 5 m / min. Depending on the extrusion speed, the hot isostatic extrusion was performed.

And, in common with each example, the wire rod extruded material is subjected to a drawing process with a reduction in area of 84% to simulate a machine part application, and a wire rod material having a circular cross section of 10 mmφ is obtained. The wire rod material was subjected to solution treatment and quenching treatment under each condition shown in Table 1, and further subjected to artificial aging treatment.

Further, a test piece was collected from the wire rod material simulating the mechanical part after the artificial aging treatment, and the average ratio of the small-angle grain boundary and the large-angle grain boundary of the specimen structure and the KAM value which is the average orientation difference were obtained. , Measured by SEM-EBSD method. In addition, the mechanical properties of the material after the artificial aging treatment were measured by simulating the properties of mechanical parts. These results are also shown in Table 1.
Incidentally, the structure after the artificial aging treatment was formed by changing various conditions such as composition, solution treatment and quenching treatment conditions, and artificial aging treatment.
At this time, as shown in Table 1, the solution treatment and the subsequent quenching treatment were performed by changing the holding temperature and time of the solution treatment, and the average cooling rate from each solution treatment temperature to 50 ° C. in various ways.

The test piece collected from the wire rod material after the artificial aging treatment is a round bar smooth tensile test piece (3 mmφ × 12 mmGL), and the extrusion direction in the middle (middle) position between the surface of the test piece and the axis center A plane (cross section) parallel to the sample was taken so as to be an observation plane.

2. Tissue measurement:
As the structure of the test piece, the average ratio between the low-angle grain boundaries and the large-angle grain boundaries and the KAM value, which is the average orientation difference, were measured by the SEM-EBSD method according to the measurement method described above. Specifically, a JEM SEM (JEOL JSM 6500F) equipped with the TSL EBSP measurement / analysis system (OIM) was used.
In each example, for the five round bar smooth tensile test pieces, the surface parallel to the extrusion direction (cross section) at the middle (middle) position between the surface of the extruded material and the shaft center was measured as the observation surface, and the test was performed. The measurement / analysis results of 5 pieces were averaged.
The measurement area of each test piece was 600 μm in the extrusion direction of the extruded material × 400 μm area (240000 μm ² ) in the direction perpendicular to the extrusion direction (extrusion material width direction), and the measurement step interval was also set to 0.5 μm in common.

3. mechanical nature:
As for the mechanical properties of the round bar smooth tensile test piece, a tensile test was performed using a tensile tester at a crosshead speed of 12 mm / min at room temperature until breakage. The tensile strength (MPa) was measured from the stress-strain rate. The total elongation (%) was calculated from the spacing between the marking lines before and after the tensile test during the tensile test (10 mm before the tensile test). In addition, these measured values were made into the average value of the said 5 test pieces in each example.

4). Summary As shown in Table 1, the inventive examples 1 to 7 in Table 1 have an aluminum alloy composition within the scope of the present invention. In addition, the extruded material is manufactured under preferable manufacturing conditions such as performing hot isostatic pressing in an unrecrystallized region. Furthermore, solution treatment, quenching treatment, and artificial aging treatment are also performed under preferable production conditions.
As a result, as shown in Table 1, the invention example shows that the average ratio of the small-angle grain boundary and the large-angle grain boundary and the average KAM value are within the specified range, the tensile strength is high strength of 800 MPa or more, and the total elongation. Has a high ductility characteristic of 5% or more.

On the other hand, in Comparative Examples 1 to 5 in Table 1, the aluminum alloy composition is outside the scope of the present invention as shown in Table 1. Therefore, in these comparative examples, although the extruded material and the simulated machine part are manufactured by a preferable manufacturing method, as shown in Table 1, the average ratio of the low-angle grain boundary and the large-angle grain boundary and / or the average KAM value. Is out of the specified range, or even if these structures are in the specified range, the tensile strength is as low as less than 800 MPa, or the total elongation is low.
In Comparative Example 1, Zn deviated from the lower limit, and the strength was insufficient.
In Comparative Example 2, Mg deviated from the lower limit and the strength was insufficient.
In Comparative Example 3, Mn deviated from the lower limit, and the strength was insufficient.
In Comparative Example 4, Mn deviated from the upper limit and the ductility was insufficient.
In Comparative Example 5, Zr deviated from the lower limit, the average ratio of the small-angle grain boundaries with an inclination of 5 to 15 ° and the average of the KAM value were small, and the strength was insufficient.

Further, in Comparative Examples 6 to 11 in Table 1, although the aluminum alloy composition is within the scope of the present invention as shown in Table 1, as shown in Table 1, the manufacturing conditions simulating machine parts are out of the preferred range. Yes. As a result, for this reason, in these comparative examples, as shown in Table 1, the average ratio of the low-angle grain boundaries and the large-angle grain boundaries and / or the average of the KAM values are pushed out of the specified range and the tensile strength is less than 800 MPa. Low and even total elongation can be low.
In Comparative Example 6, the solution treatment temperature simulating the mechanical part is too low, the amount of Zn and Mg is decreased, the average ratio of the large-angle grain boundaries exceeding the inclination angle of 15 ° is reduced, and the strength and ductility are reduced. I was short.
In Comparative Example 7, the solution treatment temperature simulating the mechanical part was too high, the average ratio of the small-angle grain boundaries with an inclination of 5 to 15 ° and the average of the KAM values were small, and the strength was insufficient.
In Comparative Example 8, the holding time of the solution treatment simulating the mechanical part was too long, the average ratio of the low-angle grain boundaries with an inclination of 5 to 15 ° and the average of the KAM values were small, and the strength was insufficient.
In Comparative Example 9, the cooling rate after the solution treatment simulating the mechanical parts was too slow, the average ratio of the small-angle grain boundaries with an inclination of 5 to 15 ° and the average of the KAM values were small, and the strength and ductility were insufficient. .
In Comparative Example 10, the temperature of the artificial aging treatment simulating the mechanical component was too high, the average ratio of small-angle grain boundaries with an inclination angle of 5 to 15 ° and the average of KAM values were small, and the strength was insufficient.
In Comparative Example 11, the retention time of the artificial aging treatment simulating the mechanical part was too long, the average ratio of the small-angle grain boundaries having an inclination angle of 5 to 15 ° and the average of the KAM value were small, and the strength was insufficient.

According to the present invention, the mechanical part made of an extruded material of 7000 series aluminum alloy having a tensile strength after artificial aging treatment of 800 MPa or more and a total elongation of 5% or more, and a manufacturing method thereof, A 7000 series aluminum alloy extruded material as a raw material can be provided. For this reason, this invention can be used suitably as said machine part reduced in weight.

The disclosure of the present specification includes the following aspects.
・ Mode 1
% By mass
Zn: 8.0 to 14.0%,
Mg: 2.0-4.0%
Cu: 0.5 to 2.0%,
Mn: 0.2 to 1.5%,
Each containing Zr: 0.05-0.3%,
A machine part having an extruded structure of a 7000 series aluminum alloy consisting of Al and inevitable impurities as the balance,
As the structure and characteristics measured by the SEM-EBSD method, the plane parallel to the extrusion direction at the intermediate position between the surface of the machine part and the axis center,
The average proportion of the low-angle grain boundaries with an inclination of 5 to 15 ° is 5% or more,
The average proportion of large-angle grain boundaries exceeding 15 ° is 20% or more,
The average KAM value is 0.3 ° or more,
Tensile strength is 800 MPa or more,
Mechanical parts characterized by a total elongation of 5% or more.
・ Aspect 2
The machine part according to aspect 1, wherein the machine part further contains one or two of Cr: 0.05 to 0.3% and Sc: 0.02 to 0.5% by mass%.
・ Aspect 3
The machine according to aspect 1 or 2, wherein the machine part further contains one or two of Ag: 0.01 to 0.6% and Sn: 0.01 to 0.2% by mass%. parts.
・ Aspect 4
In mass%, Zn: 8.0 to 14.0%, Mg: 2.0 to 4.0%, Cu: 0.5 to 2.0%, Mn: 0.2 to 1.5%, Zr: A 7000 series aluminum alloy ingot containing 0.05 to 0.3% each, the balance being Al and inevitable impurities, was extruded after soaking to form an extruded material, and this extruded material was processed into a machine part. Later, a solution treatment and a quenching treatment were performed, and an artificial aging treatment was further performed, and a surface parallel to the extrusion direction at an intermediate position between the surface of the machine part and the shaft center was measured by a SEM-EBSD method. The average ratio of small-angle grain boundaries with an inclination of 5 to 15 ° is 5% or more, the average ratio of large-angle boundaries with an inclination angle of 15 ° is 20% or more, and the average KAM value is 0.3 ° or more. And the mechanical component has a tensile strength of 800 MPa or more, Method for manufacturing a mechanical component, characterized in that the elongation 5% or more.
・ Aspect 5
The machine part according to aspect 4, wherein the machine part further contains one or two of Cr: 0.05 to 0.3% and Sc: 0.02 to 0.5% by mass%. Production method.
・ Aspect 6
The machine according to aspect 4 or 5, wherein the machine part further contains one or two of Ag: 0.01 to 0.6% and Sn: 0.01 to 0.2% by mass%. A manufacturing method for parts.
・ Aspect 7
The method for manufacturing a machine part according to any one of aspects 4 to 6, wherein the aluminum alloy ingot is extruded by hot isostatic pressing.
・ Aspect 8
% By mass
Zn: 8.0 to 14.0%,
Mg: 2.0-4.0%
Cu: 0.5 to 2.0%,
Mn: 0.2 to 1.5%,
Each containing Zr: 0.05-0.3%,
The balance is an extruded material for mechanical parts of 7000 series aluminum alloy consisting of Al and inevitable impurities,
This extruded material was a wire rod extruded material having a diameter of 25 mm with a circular cross-section, simulating a machine part, and then drawn into a wire rod material having a circular area of 10 mmφ with a reduction in area of 84%, After the solution treatment in which the wire rod is held at a temperature of 480 ° C. for 5 hours, the wire rod is quenched at an average cooling rate of up to 50 ° C. at 200 ° C./second, and then an artificial aging treatment is performed at 120 ° C. for 72 hours. The surface parallel to the extruding direction at the intermediate position between the surface of the wire rod and the shaft center and the characteristics measured by the SEM-EBSD method are as follows. The average ratio of the large-angle grain boundaries having an average ratio of 5% or more and an inclination angle of 15 ° is 20% or more, the average value of the KAM value is 0.3 ° or more, the tensile strength is 800 MPa or more, Elongation is 5% or more Extruded material.
・ Mode 9
The extruded material according to the aspect 8, wherein the extruded material further contains one or two of Cr: 0.05 to 0.3% and Sc: 0.02 to 0.5% by mass%.
Aspect 10
The extrusion according to the aspect 8 or 9, wherein the extruded material further contains one or two of Ag: 0.01 to 0.6% and Sn: 0.01 to 0.2% by mass%. Wood.

The present application includes a Japanese patent application filed on January 21, 2016, Japanese Patent Application No. 2016-009620, and a Japanese patent application filed on November 29, 2016, Japanese Patent Application No. 2016- Japanese Patent Application No. 2016-009620 and Japanese Patent Application No. 2016-231656 are incorporated herein by reference with a priority claim based on No. 231656.

Claims

% By mass
Zn: 8.0 to 14.0%,
Mg: 2.0-4.0%
Cu: 0.5 to 2.0%,
Mn: 0.2 to 1.5%,
Each containing Zr: 0.05-0.3%,
A machine part having an extruded structure of a 7000 series aluminum alloy consisting of Al and inevitable impurities as the balance,
As the structure and characteristics measured by the SEM-EBSD method, the plane parallel to the extrusion direction at the intermediate position between the surface of the machine part and the axis center,
The average proportion of the low-angle grain boundaries with an inclination of 5 to 15 ° is 5% or more,
The average proportion of large-angle grain boundaries exceeding 15 ° is 20% or more,
The average KAM value is 0.3 ° or more,
Tensile strength is 800 MPa or more,
Mechanical parts characterized by a total elongation of 5% or more.
2. The machine part according to claim 1, wherein the machine part further contains one or two of Cr: 0.05 to 0.3% and Sc: 0.02 to 0.5% by mass%. .
The machine part according to claim 1 or 2, further comprising one or two of Ag: 0.01 to 0.6% and Sn: 0.01 to 0.2% by mass%. Machine parts.
In mass%, Zn: 8.0 to 14.0%, Mg: 2.0 to 4.0%, Cu: 0.5 to 2.0%, Mn: 0.2 to 1.5%, Zr: A 7000 series aluminum alloy ingot containing 0.05 to 0.3% each, the balance being Al and inevitable impurities, was extruded after soaking to form an extruded material, and this extruded material was processed into a machine part. Later, a solution treatment and a quenching treatment were performed, and an artificial aging treatment was further performed, and a surface parallel to the extrusion direction at an intermediate position between the surface of the machine part and the shaft center was measured by a SEM-EBSD method. The average ratio of small-angle grain boundaries with an inclination of 5 to 15 ° is 5% or more, the average ratio of large-angle boundaries with an inclination angle of 15 ° is 20% or more, and the average KAM value is 0.3 ° or more. The tensile strength of this machine part is 800 MPa or more. Method for manufacturing a mechanical component, characterized in that 5% or more total elongation.
5. The machine part according to claim 4, wherein the machine part further contains one or two of Cr: 0.05 to 0.3% and Sc: 0.02 to 0.5% by mass%. Manufacturing method.
The machine part according to claim 4 or 5, further comprising one or two of Ag: 0.01 to 0.6% and Sn: 0.01 to 0.2% by mass%. Manufacturing method of machine parts.
The method for manufacturing a machine part according to any one of claims 4 and 5, wherein the aluminum alloy ingot is extruded by hot isostatic pressing.
The method for manufacturing a machine part according to claim 6, wherein the aluminum alloy ingot is extruded by hot isostatic pressing.
% By mass
Zn: 8.0 to 14.0%,
Mg: 2.0-4.0%
Cu: 0.5 to 2.0%,
Mn: 0.2 to 1.5%,
Each containing Zr: 0.05-0.3%,
The balance is an extrusion material for mechanical parts of a 7000 series aluminum alloy consisting of Al and inevitable impurities,
This extruded material was a wire rod extruded material having a diameter of 25 mm with a circular cross-section, simulating a machine part, and then drawn into a wire rod material having a circular area of 10 mmφ with a reduction in area of 84%, After the solution treatment in which the wire rod is held at a temperature of 480 ° C. for 5 hours, the wire rod is quenched at an average cooling rate of up to 50 ° C. at 200 ° C./second, and then an artificial aging treatment is performed at 120 ° C. for 72 hours. The surface parallel to the extruding direction at the intermediate position between the surface of the wire rod and the shaft center and the characteristics measured by the SEM-EBSD method are as follows. The average ratio of the large-angle grain boundaries having an average ratio of 5% or more and an inclination angle of 15 ° is 20% or more, the average value of the KAM value is 0.3 ° or more, the tensile strength is 800 MPa or more, Elongation is 5% or more Extruded material.
The extruded material according to claim 9, wherein the extruded material further contains one or two of Cr: 0.05 to 0.3% and Sc: 0.02 to 0.5% by mass%. .
The extruded material according to claim 9 or 10, further containing one or two of Ag: 0.01 to 0.6% and Sn: 0.01 to 0.2% by mass%. Extruded material.