JP6368087B2 - Aluminum alloy wire, method for producing aluminum alloy wire, and aluminum alloy member - Google Patents

Description

  The present invention relates to an aluminum alloy wire suitable for a fastening member such as a bolt or a material for an automotive part, a manufacturing method thereof, and an aluminum alloy member. In particular, the present invention relates to an aluminum alloy wire suitable for a material of an aluminum alloy member that requires high strength and heat resistance.

  Since aluminum alloys are lighter than iron-based materials, they are used for materials such as parts for electrical and electronic equipment, parts for vehicles such as automobiles, and industrial machines. In particular, in the automobile field, weight reduction has been actively promoted in order to improve fuel consumption, and the use of aluminum alloy members is expanding. In particular, 6000 series (Al-Si-Mg series) aluminum alloys with international alloy symbols have the strength next to 2000 series (Al-Cu series) and 7000 series (Al-Zn-Mg series), and 2000 series. Since it is more excellent in corrosion resistance than 7000 series, it is used for fastening members such as automobile parts and bolts used for fastening aluminum alloy members.

Among the 6000 series aluminum alloys, A6056 is known as a high-strength alloy. A6056 is an alloy with increased strength by increasing the concentration of Mg, Si, and Cu, and the tensile strength of the T6 material reaches 425 MPa and the 0.2% proof stress reaches 375 MPa. Patent Document 1 specifies a composition of a 6000 series (more specifically, A6056 equivalent) aluminum alloy, and further specifies a ratio between the content of Mg ₂ Si and the total content of Mn and Cr. An aluminum alloy wire for bolts having high strength and excellent formability (workability) to bolts by adjusting to the range is disclosed.

JP2013-104122A

  Recently, with the expansion of the range of use of aluminum alloy members, high strength and heat resistance may be required for aluminum alloy members. For example, in the case of bolts for automobiles, they are often used at high temperatures, and have the strength necessary for fastening, and heat resistance is required to maintain them even at high temperatures.

  When an aluminum alloy is exposed to a high temperature of 120 ° C. or higher for a long time, recrystallization, disappearance of strain, and overaging depending on the alloy system proceed, so that the mechanical strength gradually decreases. For this reason, aluminum alloy members such as bolts and automobile parts need to have a redundant design on the premise of a decrease in mechanical strength or need to limit the operating temperature. Therefore, there are problems such as increasing the thickness and limiting the range of use by increasing the thickness in order to ensure reliability.

  Therefore, it is desired to develop an aluminum alloy wire suitable for a material of an aluminum alloy member that requires high strength and heat resistance.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide an aluminum alloy wire suitable for a material of an aluminum alloy member that requires high strength and heat resistance, and a method for producing the same. It is in. Another object of the present invention is to provide an aluminum alloy member having high strength and excellent heat resistance.

  The aluminum alloy wire of the present invention has a composition in which, by mass, Si and Mg are each 0.7% or more, Cu and Zn are 1.5% or less, and the balance is Al and inevitable impurities. After solution treatment at 550 ° C., the tensile strength after further aging treatment at 170 ° C. × 8 hours is 400 MPa or more, and after the aging treatment, the tensile strength after a heat resistance test at 150 ° C. × 1000 hours. Is 370 MPa or more.

The manufacturing method of the aluminum alloy wire of the present invention includes the following casting process, rolling process, and wire drawing process.
Casting process: Continuous casting of an aluminum alloy having a composition of 0.7% or more of Si and Mg and 1.5% or less of Cu and Zn respectively, with the balance being Al and inevitable impurities. The process of obtaining cast material.
Rolling step: A step of rolling the cast material into a rolled material.
Wire drawing step: A step of drawing the rolled material into a wire drawing material having a predetermined wire diameter.
The wire drawing step includes continuous wire drawing until the degree of processing reaches 30% or more and 90% or less.

  The aluminum alloy member of the present invention is obtained by processing the aluminum alloy wire of the present invention.

  The aluminum alloy wire of the present invention is suitable for a material of an aluminum alloy member that requires high strength and heat resistance. The method for producing an aluminum alloy wire of the present invention can produce an aluminum alloy wire suitable for a material of an aluminum alloy member that requires high strength and heat resistance. The aluminum alloy member of the present invention has high strength and excellent heat resistance.

  The present inventors have studied to improve heat resistance by optimizing the manufacturing process of the aluminum alloy wire. As a result, it has been found that heat resistance can be improved by performing specific wire drawing in the wire drawing process. Based on the above findings, the present inventors have completed the present invention.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.

  (1) The aluminum alloy wire according to the embodiment includes, by mass%, 0.7% or more of Si and Mg and 1.5% or less of Cu and Zn, respectively, with the balance being Al and inevitable impurities. Having a composition. And after the solution treatment at 550 ° C., the tensile strength after further aging treatment at 170 ° C. × 8 hours is 400 MPa or more, and after aging treatment, the tensile strength after the heat resistance test at 150 ° C. × 1000 hours. Is 370 MPa or more.

  The aluminum alloy wire contains 0.7 mass% or more of Si and Mg, respectively, and has a basic composition of a 6000 series (Al-Si-Mg series) aluminum alloy, so that strength, heat resistance, corrosion resistance, and workability are achieved. At a relatively high level. Moreover, the fall of corrosion resistance and workability by containing Cu and Zn can be suppressed by containing Cu and Zn each 1.5% or less. The aluminum alloy wire is typically a round wire having a circular cross section.

  Further, the aluminum alloy wire has a tensile strength after the solution treatment and after the aging treatment (hereinafter sometimes referred to as “first tensile strength”) of 400 MPa or more, and has high strength. Have. Furthermore, after the above aging treatment after the above solution treatment, the tensile strength after the above heat resistance test (hereinafter sometimes referred to as “second tensile strength”) is 370 MPa or more. Can maintain its tensile strength and has excellent heat resistance. Therefore, the aluminum alloy wire is suitable for a material of an aluminum alloy member that requires high strength and heat resistance.

  (2) As one form of the said aluminum alloy wire, it is mentioned that the tensile strength after a heat test is 85% or more of the tensile strength after an aging treatment.

  According to the said form, the maintenance rate of 2nd tensile strength with respect to 1st tensile strength is high, and it is more excellent in heat resistance.

  By the way, after the aluminum alloy wire is cut to a predetermined length, it is molded by plastic working and processed into an aluminum alloy member. For example, in the case of a bolt, an aluminum alloy wire cut to a predetermined length is compressed and deformed in the longitudinal direction by forging to form a bolt head portion. In the bolt manufacturing process, the most severe processing is forging of the bolt head portion, which corresponds to about 70% when converted into a compression ratio. Therefore, it is desired that the aluminum alloy wire has excellent compression workability that does not crack or cause wrinkles on the surface even if it is greatly compressed and deformed.

  Furthermore, as a result of repeated research by the present inventors, when a round wire of an aluminum alloy wire cut to a predetermined length is compressed and deformed in the longitudinal direction, a processing history in the manufacturing process (particularly, rolling in the rolling process). It has been found that the outer shape viewed from the compression direction may be deformed from a circular shape to a non-circular shape (eg, substantially triangular shape) depending on the history. Specifically, when compressively deformed in the longitudinal direction, the wire does not deform isotropically in the radial direction, the deformation becomes non-uniform, and the outer shape may be deformed from a circular shape to an irregular shape (non-circular shape). . In particular, such a phenomenon is likely to occur when compression deformation is performed to 40% to 20% of the original length. Thus, if the deformation is not uniform when compressively deformed in the longitudinal direction, an abnormal shape is obtained when the aluminum alloy member is processed, and the yield of the aluminum alloy member may be reduced. Therefore, in an aluminum alloy wire, it is desired that it is difficult to deform into an irregular shape even if it is compressed and deformed as one index of compressibility.

  (3) As one form of the said aluminum alloy wire, it is mentioned that the limit compressibility when it is compressively deformed in the longitudinal direction is 80% or more.

  According to the said form, a limit compression rate is 80% or more, and it is excellent in compression work property at the point which is hard to produce a crack even if it compresses and deforms to a longitudinal direction. The higher the critical compression ratio, the less likely it is to crack against large compression deformations. Details of the limit compression rate will be described later.

  (4) As one form of the aluminum alloy wire, the degree of compressive deformation when compressed and deformed to 40%, 30%, and 20% of the original length in the longitudinal direction is 0.1 or less, respectively. Is mentioned.

  According to the above aspect, the degree of compressive deformation is 0.1 or less, and excellent compressibility is obtained in that it is difficult to deform from a circular shape to an irregular shape even if it is compressed and deformed in the longitudinal direction. The smaller the degree of compressive deformation, the closer the outer shape after compressive deformation is to a circle. A detailed description of the degree of compression deformation will be described later.

  (5) As one form of the aluminum alloy wire, the maximum value of the arithmetic average roughness Ra of the side surface is 0.5 mm or less when the aluminum alloy wire is compressed and deformed to 15% of the original length in the longitudinal direction. Can be mentioned.

  According to the said form, the maximum value of arithmetic mean roughness Ra of a side surface is 0.5 mm or less, and it is excellent in compression workability at the point which is hard to produce a wrinkle on a side surface even if it compressively deforms in a longitudinal direction. The smaller the arithmetic average roughness Ra, the smoother the surface and the better the surface properties. A detailed description of the arithmetic average roughness Ra of the side will be described later.

  (6) As one form of the said aluminum alloy wire, having the structure | tissue whose 111-plane orientation degree in the X-ray diffraction of a cross section is 0.5 or more is mentioned.

  According to the said form, it is excellent in heat resistance and workability (especially compression workability) because the orientation degree of 111 surface is 0.5 or more. As a result of repeated researches by the present inventors, in an aluminum alloy wire, the texture of the cross section (cross section perpendicular to the longitudinal direction of the wire) is oriented in the 111 plane, so that the heat resistance can be further improved and the compressibility can be improved. I got the knowledge that it is even better. The reason is considered as follows. If the cross section is oriented in the 111 plane, that is, if the 111 plane is oriented in a direction perpendicular to the longitudinal direction of the wire, slip deformation is unlikely to occur in the longitudinal direction with respect to tension. In particular, strengthening by orientation of the 111 plane is unlikely to attenuate even at high temperatures, unlike strengthening by aging precipitation or processing strain. Therefore, a decrease in tensile strength can be suppressed even at high temperatures, and heat resistance is improved. In addition, when the cross section is oriented in the 111 plane, slip deformation is likely to occur in the radial direction of the wire, and deformation is likely to occur in the radial direction. That is, when compressively deformed in the longitudinal direction, it is easily deformed in the radial direction, and compression workability is improved. A detailed description of the degree of orientation of the 111 plane will be described later.

  (7) As one form of the said aluminum alloy wire, having an organization whose average crystal grain size is 70 micrometers or less is mentioned.

  According to the said form, when an average crystal grain diameter is 70 micrometers or less, the size of a crystal grain diameter is small, and heat resistance and workability (especially compression workability) improve. When coarse crystal grains are present in the structure, stress concentration occurs, which may be the starting point to reduce the tensile strength, and may cause cracks or wrinkles when compressively deformed. If it is a fine crystal structure, the fall of the tensile strength resulting from a coarse crystal grain can be suppressed, or the crack and flaw which generate | occur | produce when carrying out compression deformation can be reduced. A detailed description of the average crystal grain size will be described later.

  (8) As one form of the said aluminum alloy wire, having a structure | tissue whose variation degree of a crystal grain diameter is 0.5 or less is mentioned.

  According to the said form, when the variation degree of a crystal grain diameter is 0.5 or less, the variation in crystal grain diameter is small, and heat resistance and workability (especially compression workability) improve. Since the crystal grain size is uniform, the stress is applied uniformly, so it is possible to suppress a decrease in tensile strength due to stress concentration, and to reduce cracks and wrinkles that occur when compressively deformed. In particular, when the average crystal grain size is 70 μm or less and the degree of variation in crystal grain size is a fine and homogeneous crystal structure, the effect of improving heat resistance and workability is great. A detailed description of the degree of variation in crystal grain size will be described later.

  (9) As one form of the aluminum alloy wire, in mass%, Si: 0.9% to 1.3%, Mg: 0.8% to 1.2%, Fe: 0% to 0.4 %: Cu: 0.65% to 1.1%, Mn: 0.55% to 1.15%, Cr: 0% to 0.35%, Zn: 0.12% to 0.25 % Or less, Ti: 0% or more and 0.075% or less, Zr: 0.05% or more and 0.17% or less. And [{(excess Si amount) + (Fe content)} / (Mn content)] which is the ratio of the sum of the excess Si amount and the Fe content and the Mn content is 0.5 or more. It is 1.8 or less. Hereinafter, this composition may be referred to as “first composition”.

  The above composition has a basic composition of A6056 and combines strength, heat resistance, corrosion resistance, and workability at a higher level. In particular, the ratio of the excess Si amount, the total Fe content (% by mass), and the Mn content (% by mass) [{(excess Si amount) + (Fe content)} / (Mn content) ] Satisfies a specific range, workability is improved. The reason is considered as follows. When the amount of excess Si and the Fe concentration are high, an Al-Fe-Si crystallized product is generated, which is advantageous for increasing the strength by dispersing it, but the Al-Fe-Si crystallized product becomes coarse and workability is increased. Cause a decline. However, by containing an appropriate amount of Mn, the shape of the Al-Fe-Si crystallized product approaches a spherical shape, and the deterioration of workability can be suppressed. And, as a result of investigation by the present inventors on the ratio of excess Si amount, Fe content and Mn content, [{(excess Si amount) + (Fe content)} / (Mn content)] is 0. It was found that it is preferable to satisfy .5 or more and 1.8 or less.

  The excess Si amount is determined by using the Si content (mass%) and the Mg content (mass%), [(Si content) − {(Mg content) / (24.3 × 2)} × 28. .. 1] ... (Expression 1) The numerical value “24.3” is based on the atomic weight of Mg, and the numerical value “28.1” is based on the atomic weight of Si.

  (10) As one form of the said aluminum alloy wire, content of each element in the said composition is mass%, Si: 0.9% or more and 1.2% or less, Mg: 0.8% or more and 1.0% Hereinafter, Fe: 0% to 0.25%, Cu: 0.65% to 0.85%, Mn: 0.55% to 0.65%, Cr: 0% to 0.05%, Zn: 0.15% to 0.25%, Ti: 0% to 0.05%, Zr: 0.11% to 0.17%.

  The said form which limited content of each said element with respect to the above-mentioned 1st composition has intensity | strength, heat resistance, corrosion resistance, and workability on a still higher level.

(11) The manufacturing method of the aluminum alloy wire according to the embodiment includes the following casting process, rolling process, and wire drawing process.
Casting process: Continuous casting of an aluminum alloy having a composition of 0.7% or more of Si and Mg and 1.5% or less of Cu and Zn respectively, with the balance being Al and inevitable impurities. The process of obtaining cast material.
Rolling step: A step of rolling the cast material into a rolled material.
Wire drawing step: A step of drawing the rolled material into a wire drawing material having a predetermined wire diameter.
The wire drawing step includes continuous wire drawing until the degree of processing reaches 30% or more and 90% or less.

  The manufacturing method of the aluminum alloy wire described above has high strength and excellent heat resistance by performing at least one set of continuous wire drawing until the degree of work reaches 30% or more and 90% or less in the wire drawing step. Aluminum alloy wire can be manufactured. Therefore, it is possible to obtain an aluminum alloy wire suitable for a material of an aluminum alloy member that requires high strength and heat resistance. The reason is considered as follows. By performing continuous wire drawing until the degree of work reaches 30% or more and 90% or less, the texture of the cross section of the wire can be controlled to be oriented in the 111 plane, and the heat resistance can be improved as described above. Enhanced. Further, by orienting the texture of the cross section in the 111 plane, it is excellent in compression workability as described above. In particular, when the processing strain is accumulated in the wire, orientation to the 111 plane occurs more efficiently. Here, if a heat treatment such as an intermediate softening process is performed in the middle of the wire drawing process, the strain introduced by the process is released, so that the orientation to the 111 plane hardly occurs. Therefore, it is preferable to perform the wire drawing process continuously. Specifically, even if continuous wire drawing is performed so that the degree of processing is 20%, intermediate softening treatment is performed, and then continuous wire drawing is performed so that the degree of processing is further 20%. , Orientation to the 111 plane becomes insufficient. On the other hand, if the wire drawing is continuously performed until the degree of processing reaches 30% or more and 90% or less, the orientation of the 111 plane becomes strong. A preferable range of the degree of processing is 40% or more. Further, even if heat treatment such as intermediate softening is performed thereafter, the orientation of the 111 plane introduced by the processing is maintained. In this case, for example, after the continuous drawing process is performed so that the processing degree becomes 30%, the intermediate softening treatment may be performed, and then the continuous drawing process may be performed so that the processing degree further becomes 10%. On the contrary, after continuous drawing at a workability of 10%, the intermediate softening treatment may be followed by continuous drawing at a workability of 30%. Further, after continuous drawing at a workability of 10%, the intermediate softening treatment may be followed by continuous drawing at a workability of 30%, and then the intermediate softening treatment and the drawing work may be repeated. That is, it is sufficient to perform continuous wire drawing at a work degree of 30% or more and 90% or less at least once at any timing during the wire drawing process.

  (12) As one form of the manufacturing method of the said aluminum alloy wire, it is mentioned that a solidification rate shall be 1 degree-C / sec or more in a casting process.

  According to the said form, by making the solidification speed | rate of a casting process 1 degree-C / sec or more, the production | generation and coarsening of a crystallized substance can be suppressed favorably, and a crack and a disconnection arise in the wire drawing process of a post process. hard. In addition, it is possible to suppress the formation of coarse crystallized substances that can be the starting point of cracks, and furthermore, the crystal grains can be refined by such rapid cooling, so that aluminum not only has excellent strength and heat resistance but also has excellent workability. An alloy wire can be manufactured.

  (13) As one form of the manufacturing method of the said aluminum alloy wire, after a continuous wire drawing process, performing an intermediate softening process below 450 degreeC for 1 hour or more and 100 hours or less is mentioned.

  According to the said form, by performing an intermediate | middle softening process, the distortion introduced by the wire drawing process before an intermediate | middle softening process is removed and it softens, and it becomes easy to perform a subsequent wire drawing process.

  (14) As one form of the manufacturing method of the said aluminum alloy wire, after a rolling process, before a wire drawing process, performing a softening process for 1 hour or more and 100 hours or less at less than 450 degreeC is mentioned.

  According to the said form, by performing a softening process after a rolling process and before a wire drawing process, it removes the introduced distortion and softens it by rolling, and it becomes easy to perform subsequent wire drawing. In particular, since non-uniform strain is easily introduced in rolling, workability can be improved by releasing the strain by softening treatment.

  (15) The aluminum alloy member according to the embodiment is obtained by processing the aluminum alloy wire according to the embodiment described in any one of the above (1) to (10).

  The aluminum alloy member has high strength and is excellent in heat resistance, and is therefore suitable as a member that is lightweight and requires high strength and heat resistance. Examples of the aluminum alloy member include automotive parts such as a spool valve in addition to fastening members such as bolts and rivets.

  (16) One form of the aluminum alloy member is a bolt.

  (17) One form of the aluminum alloy member is an automotive part.

[Details of the embodiment of the present invention]
Specific examples of the aluminum alloy wire according to the embodiment, the manufacturing method thereof, and the aluminum alloy member will be described below. In addition, this invention is not limited to these illustrations, is shown by the claim, and intends that all the changes within the meaning and range equivalent to the claim are included.

[Aluminum alloy wire]
<Composition>
The composition of the aluminum alloy wire is, by mass%, containing 0.7% or more of Si and Mg and 1.5% or less of Cu and Zn, respectively, the balance being Al and inevitable impurities, 6000 series (Al Based on the composition of (-Si-Mg) aluminum alloy. An example of the composition is a composition corresponding to A6056. Hereinafter, the content and effect of each additive element will be described.

Si: 0.9% or more and 1.3% or less Si dissolves in Al together with Mg by solution treatment, precipitates as fine Mg ₂ Si by aging treatment (artificial aging), and strengthens the aluminum alloy. In addition, Si (excess Si) remaining after the reaction with Mg solidifies in Al, precipitates, or crystallizes in a dendritic form, thereby strengthening the aluminum alloy. On the other hand, when excessive Si is excessive, segregation to the grain boundary becomes excessive and embrittles. By containing 0.9% or more of Si, the above-described strengthening effect can be appropriately expressed, and an aluminum alloy wire having a predetermined strength and an aluminum alloy member having a high strength can be obtained. By containing Si in the range of 1.3% or less, grain boundary embrittlement can be suppressed, and high strength and workability can be improved. For example, the workability when performing various plastic workings in the process of processing from a cast material to a wire or the forming process from a wire to an aluminum alloy member (for example, a bolt) is difficult to be hindered. And by containing Si in the range of 1.3% or less, it is possible to suppress the formation of coarse crystallized substances and precipitates that are the starting points of cracks during plastic working. As a result, not only the strength of the aluminum alloy wire is increased, but also the heat resistance and workability are improved. A more preferable Si content is 0.9% or more and 1.2% or less.

Mg: 0.8% or more and 1.2% or less Mg strengthens the aluminum alloy by solid solution strengthening and forms an aging precipitate that contributes to strength improvement together with Si by performing aging treatment. Improve strength. By containing 0.8% or more of Mg, an aluminum alloy wire having a predetermined strength that can sufficiently obtain the strength improvement effect by solid solution strengthening and precipitation hardening, and further an aluminum alloy member having high strength and heat resistance Can be obtained. However, when Mg is contained excessively, it becomes difficult to obtain the strengthening effect due to the excessive Si described above, and mechanical properties such as strength and heat resistance are lowered, and the component is likely to cause macro segregation during casting, The Mg content is preferably 1.2% or less because resistance to stress corrosion cracking is reduced or workability is reduced. A more preferable Mg content is 0.8% or more and 1.0% or less.

-Fe: 0% or more and 0.4% or less When Fe is not contained (in the case of 0%), the total content of the additive elements is small, and deterioration of workability due to high concentration of the additive elements can be suppressed, and workability is reduced. Excellent. In this case, since there are few kinds of melt | dissolution raw materials at the time of casting, the time required for adjustment of a molten metal can be shortened and it is excellent in productivity. Further, in this case, since the solidus temperature is lowered, the casting temperature can be lowered, and the temperature raising time to the casting temperature can be shortened, so that productivity is excellent. When Fe is contained (when it exceeds 0%), Fe is dissolved in the matrix to strengthen the aluminum alloy. As the amount of Fe dissolved increases, the aluminum alloy becomes harder, and as a result, mechanical properties such as strength and heat resistance tend to be improved. Fe solid solution suppresses segregation of grain boundaries of Si and suppresses embrittlement of grain boundaries. In addition, by using rapid cooling by continuous casting in the manufacturing process, a sufficient amount of Fe can be dissolved, and the above-described effects of solid solution strengthening and segregation suppression can be appropriately obtained. As a result, Mg ₂ Si and the like can be obtained. It is easy to obtain the strength improvement effect by precipitation hardening of the precipitate. Therefore, when it contains Fe, it is preferable to contain 0.1% or more. However, if Fe is contained excessively, the workability is lowered, so the Fe content is preferably 0.4% or less. By containing Fe in the range of 0.4% or less, Fe-based crystallized substances (Al—Fe compounds such as Al—Fe—Si) are excessively generated, and the plastic workability of the alloy is reduced. Can be suppressed. Therefore, plastic work materials such as aluminum alloy wires subjected to rolling or wire drawing and aluminum alloy members such as bolts subjected to forging can be manufactured with high productivity. In addition, an aluminum alloy wire having a predetermined strength, and an aluminum alloy member having high strength and heat resistance can be obtained. In addition, in the case of containing Fe and an element having an effect of crystal refining including Ti, crystallization by the above element during casting in the presence of an alkaline earth metal element (for example, Mg or Sr to be described later) It is also possible to promote the refinement of the film, and a fine crystal structure can be obtained. A cast material having a fine crystal structure can improve the workability after casting. In addition, an improvement in strength due to the fine structure can be expected to some extent. A more preferable Fe content is 0.25% or less.

Cu: 0.65% or more and 1.1% or less Cu precipitates in the matrix as an Al—Cu compound and contributes to strength improvement together with Si, Mg and the like. By containing 0.65% or more of Cu, it is easy to obtain the strength improvement effect. However, if Cu is contained excessively, the workability deteriorates, so the Cu content is preferably 1.1% or less. A more preferable Cu content is 0.65% or more and 0.85% or less.

Mn: 0.55% or more and 1.15% or less Mn partially dissolves in the matrix and strengthens the aluminum alloy. Further, Mn forms Al—Mn-based dispersed particles and suppresses coarsening of crystal grains constituting the alloy structure. In particular, the dispersed particles suppress the coarsening of crystal grains during heat treatment such as solution treatment and aging treatment, thereby contributing to refinement of the crystal structure, and are effective in improving heat resistance. By miniaturizing the alloy structure, effects such as improvement in strength, improvement in workability, and improvement in corrosion resistance can be expected. By containing 0.55% or more of Mn, it is easy to obtain the above effect. In addition, an Al—Fe compound that usually crystallizes in a needle shape crystallizes spherically in the presence of Mn. Since the crystallized product has a less adverse effect on the workability when it is spherical, it is possible to suppress a decrease in workability by containing an appropriate amount of Mn. However, if the content of Mn is too large, coarse crystallized substances and precipitates that can be the starting point of cracking are formed, and this causes a decrease in workability. Further, when Mn increases, the solidus temperature of the molten metal rises, so that it is necessary to raise the casting temperature, leading to a decrease in productivity. Accordingly, the Mn content is preferably 1.15% or less. A more preferable Mn content is 0.55% or more and 0.65% or less.

-Cr: 0% or more and 0.35% or less When Cr is not contained (in the case of 0%), the total content of additive elements is small, and the processability is excellent as described above. In this case, like Fe, the productivity is excellent by shortening the adjustment time of the molten metal and lowering the casting temperature. On the other hand, when Cr is contained (in the case of more than 0%), dispersed particles are formed in the same manner as Mn described above, contributing to the refinement of crystals and improving the strength. Cr also has the effect of improving heat resistance and corrosion resistance. Therefore, when it contains Cr, it is preferable to contain 0.02% or more. Thereby, it is easy to obtain an aluminum alloy wire having high strength and heat resistance, and further an aluminum alloy member excellent in strength and heat resistance. However, when there is too much content of Cr, the coarse crystallized substance and precipitate which may become a crack starting point are formed, and the fall of workability is caused. Further, when Cr is increased, productivity is lowered due to an increase in casting temperature as in Mn. Therefore, when Cr is contained, the content of Cr is preferably 0.35% or less, and more preferably 0.05% or less.

Zn: 0.12% or more and 0.25% or less Zn precipitates as an Al—Zn compound, and a strengthening effect by precipitation hardening is obtained. By containing Zn at 0.12% or more, it is easy to obtain a strengthening effect. However, if Zn is contained excessively, the corrosion resistance and heat resistance are lowered, and therefore the Zn content is preferably 0.25% or less. A more preferable Zn content is 0.15% or more and 0.25% or less.

Ti: 0% or more and 0.075% or less When Ti is not contained (in the case of 0%), the total content of the additive elements is small, and the processability is excellent as described above. In this case, like Fe, the productivity is excellent by shortening the adjustment time of the molten metal and lowering the casting temperature. On the other hand, when Ti is contained (in the case of more than 0%), the effect of making the crystal structure of the cast material fine or suppressing the ratio of columnar crystals in the cast material to increase the ratio of equiaxed crystals is obtained. It is done. As a result, when Ti is contained, workability when performing plastic processing after casting, for example, rolling, wire drawing, forging, etc., can be improved by refining the crystal structure of the cast material. Further, since the crystal structure becomes fine, it is difficult to generate wrinkles and wrinkles at the time of plastic processing, and it is possible to obtain a plastic processed material having less wrinkles and wrinkles and excellent surface properties. Furthermore, since the crystal structure is fine, an improvement in strength and heat resistance can be expected. The larger the Ti content, the more the above-mentioned miniaturization effect. Therefore, when Ti is contained, it is preferably contained in an amount of 0.001% or more, and more preferably 0.01% or more, whereby the above-described miniaturization effect and the effects resulting from this effect are easily obtained. However, if the Ti content is too large, the workability and productivity may be reduced due to the increase in additive elements. Therefore, the Ti content is preferably 0.075% or less. A more preferable Ti content is 0.05% or less . In addition to Ti alone, a compound such as TiB ₂ or an alloy such as Al—Ti—B can be used for addition of Ti. B, like Ti, has an effect of improving the strength by making the crystal structure fine. Therefore, the aluminum alloy is allowed to contain B in a mass ratio of about 50 ppm or less.

-Zr: 0.05% or more and 0.17% or less When Zr is contained, heat resistance can be improved. Further, when Zr is contained, similarly to Mn, dispersed particles containing Zr are formed, and the coarsening of the crystal grains during the heat treatment described above is suppressed, thereby contributing to the refinement of the crystal structure. As a result, the effect of improving the strength and the effect of improving the workability associated with the fine crystal structure can be expected. By containing 0.05% or more of Zr, the effect of improving the heat resistance and the effect of improving the strength and workability due to the above-mentioned miniaturization can be obtained appropriately. When Zr is contained in the range of 0.17% or less, it is possible to suppress a decrease in workability due to the formation of coarse crystallized products and precipitates. Further, when Zr is increased, the productivity is lowered due to an increase in the casting temperature as in Fe and Cr. A more preferable content of Zr is 0.11% or more and 0.17% or less.

-Other elements Sr is mentioned as another additive element. Sr has the effect of refining the crystal structure of the cast material. In particular, when Sr is contained in the presence of Si, the crystallized size of Si can be reduced, and plastic workability such as rolling and wire drawing can be improved. When Sr is contained, the content of Sr is preferably 0.005% or more and 0.05% or less, and more preferably 0.005% or more and 0.03% or less.

-[{(Excess Si content) + (Fe content)} / (Mn content)]: 0.5 or more and 1.8 or less As described above, a part of Si is converted into Al together with Mg by solution treatment. It dissolves and precipitates as fine Mg ₂ Si by artificial aging, and the remainder of Si (the above-mentioned excess Si) strengthens the aluminum alloy by solid solution, precipitation, and crystallization. Here, when Fe is contained, excess Si combines with Fe to produce an Al-Fe-Si crystallized product, thereby contributing to an increase in strength. However, if the excess Si amount or Fe concentration is high, Al The -Fe-Si crystallized product becomes coarse and causes a decrease in workability. On the other hand, by containing an appropriate amount of Mn, the shape of the Al-Fe-Si crystallized product approaches a spherical shape, and the deterioration of workability can be suppressed. Therefore, [{(excess Si amount) + (Fe content)} / (Mn content)] is defined. If this is 0.5 or more and 1.8 or less, Al—Fe—Si crystallizes into a spherical shape due to the presence of Mn sufficiently with respect to {(excess Si amount) + (Fe content). Can alleviate adverse effects on sex. More preferably, [{(excess Si amount) + (Fe content)} / (Mn content)] is 0.8 or more and 1.2 or less. The excess Si amount is obtained from the above (Equation 1).

<Shape and wire diameter>
The shape of the aluminum alloy wire is not particularly limited, but is typically a round wire or a flat wire. Moreover, what is necessary is just to select the wire diameter (a diameter in a round wire, thickness and width in a flat wire) of an aluminum alloy wire according to a use etc., for example, about 3 mm or more and 15 mm or less are mentioned.

<Tensile strength (strength / heat resistance)>
Aluminum alloy wire has high strength and excellent heat resistance. Specifically, the tensile strength (first tensile strength) after solution treatment at 550 ° C. and further aging treatment at 170 ° C. for 8 hours is 400 MPa or more. And after the said aging treatment after the said solution treatment, the tensile strength (2nd tensile strength) after carrying out the heat test of 150 degreeC x 1000 hours is 370 Mpa or more. The solution treatment time may be 15 minutes or more and 120 minutes or less. Depending on the composition, production conditions, solution treatment and aging treatment conditions, higher strength and heat resistance may be achieved. For example, the solution treatment may be 550 ° C. or more and 580 ° C. or less × 15 minutes or more and 120 minutes or less, and the aging treatment may be 160 ° C. or more and 180 ° C. or less × 4 hours or more. The first tensile strength is preferably 410 MPa or more, more preferably 415 MPa or more, further preferably 422 MPa or more, and particularly preferably 425 MPa or more. On the other hand, the second tensile strength is preferably 375 MPa or more, more preferably 380 MPa or more, still more preferably 386 MPa or more, and particularly preferably 390 MPa or more. Further, from the viewpoint of maintaining the tensile strength even at high temperatures, the second tensile strength is 85% or more, 88% or more, more than 90%, particularly 92% or more of the first tensile strength. preferable.

  For the tensile strength of the aluminum alloy wire, a test piece for measurement was prepared in accordance with JIS Z 2241 (2011), and this solution was subjected to the above solution treatment, aging treatment, and heat resistance test as appropriate. Can be measured by a tensile test.

<Compressive processability>
Aluminum alloy wire is used as a material for aluminum alloy members, and is processed into aluminum alloy members. Therefore, it is desirable to have excellent workability, and in particular, it is subjected to processing that compresses and deforms in the longitudinal direction like bolts. When it is, it is desirable to be excellent in compression workability. Examples of the index of compressibility include the limit compression rate, the degree of compression deformation, the surface roughness of the side surface after compression deformation, and the like.

(Limit compression rate)
It is preferable that the critical compression ratio when compressed and deformed in the longitudinal direction is 80% or more. As described above, the limit compression rate represents the difficulty of cracking when compressed and deformed in the longitudinal direction. The critical compression rate (%) is measured as follows. When a test piece cut out from an aluminum alloy wire is compressed and deformed in the longitudinal direction until cracking occurs, the original height before compressive deformation is h ₁ , and the height when the crack is generated is h ₂ [( h ₁ − h ₂ ) / h ₁ × 100] is defined as the critical compression rate (%). The test piece is prepared so that the ratio of diameter to length (aspect ratio) is 1: 2. Moreover, a crack means the thing of 0.05 mm or more which observes the side surface of a test piece visually or with an optical microscope. If the critical compression rate is 80% or more, it can be said that the compression performance is good, and it is considered that there is a sufficient margin for forging of the bolt head portion. A more preferable limit compression rate is 85% or more, and further more than 85%.

(Compression deformation)
It is preferable that the degree of compressive deformation when compressively deformed to 40%, 30%, and 20% of the original length in the longitudinal direction is 0.1 or less. As described above, the degree of compressive deformation represents the difficulty of deformation of the outer shape as viewed from the compression direction when being compressed and deformed in the longitudinal direction. The degree of compression deformation is measured as follows. The test piece cut out from the aluminum alloy wire (round wire) is compressed and deformed to 40%, 30% and 20% of the original length in the longitudinal direction. Then, in each test piece after compression deformation, an inscribed circle and a circumscribed circle of the outer shape of the projected image projected from the compression direction are obtained, and the difference between the radii of these two circles is divided by the average value of the radii of the two circles. The value is the compression deformation. That is, when the radius of the inscribed circle is ri and the radius of the circumscribed circle is ro, [(ro-ri) / {(ro + ri) / 2}] is the degree of compressive deformation. The test piece is prepared so that the ratio of diameter to length (aspect ratio) is 1: 2. In any case when the compression deformation is 40%, 30%, or 20% of the original length, if the degree of compression deformation is 0.1 or less, the outer shape is circular even if compression deformation is performed in the longitudinal direction. Therefore, it can be said that it has a good compression workability. A more preferable degree of compressive deformation is 0.05 or less.

(Surface roughness of the side)
It is preferable that the maximum value of the arithmetic average roughness Ra of the side surface is 0.5 mm or less when compression-deformed to 15% of the original length in the longitudinal direction. As described above, the arithmetic average roughness Ra of the side surface represents the difficulty in generating wrinkles when compressively deformed in the longitudinal direction. The arithmetic mean roughness Ra of the side surface is 20 at regular intervals in the circumferential direction of the side surface of the test piece after compression deformation of the test piece cut out from the aluminum alloy wire to 15% of the original length in the longitudinal direction. A dot is obtained by measuring the arithmetic average roughness Ra on a straight line parallel to the longitudinal direction passing through each point. The test piece is prepared so that the ratio of diameter to length (aspect ratio) is 1: 2. If the maximum value of the arithmetic average roughness Ra of the side surface is 0.5 mm or less, it can be said that the surface is smooth and wrinkles that cause defective products are not generated, and therefore, it has good compressibility. More preferably, the maximum value of the arithmetic average roughness Ra is 0.2 mm or less.

<Organization>
As a result of investigating the structure of the aluminum alloy wire excellent in heat resistance and workability (compression workability), the present inventors have found that the following crystal orientation and crystal grain size are satisfied.

(Degree of orientation of 111 plane)
It is mentioned that the degree of orientation of the 111 plane in the X-ray diffraction of the cross section (cross section orthogonal to the longitudinal direction of the wire) is 0.5 or more. As described above, since the texture of the cross section is oriented in the 111 plane, slip deformation hardly occurs in the longitudinal direction with respect to the tension, and the strengthening by the orientation of the 111 face is different from the strengthening by aging precipitation or processing strain. Difficult to attenuate even at high temperatures. Therefore, a decrease in tensile strength can be suppressed even at high temperatures, and heat resistance is improved. In addition, when the cross section is oriented in the 111 plane, slip deformation is likely to occur in the radial direction of the wire, and deformation is likely to occur in the radial direction. That is, when compressively deformed in the longitudinal direction, it is easily deformed in the radial direction, and compression workability is improved. When the degree of orientation of the 111 plane is 0.5 or more, it has high strength and heat resistance and is excellent in compression workability. In particular, it is easily deformed into a circular shape when compressed and deformed in the longitudinal direction, and satisfies the above-described degree of compressive deformation. The orientation degree of the 111 plane is more preferably 0.6 or more, and further 0.7 or more.

The degree of orientation of the 111 plane is determined by measuring the peak intensity of each of the 111, 200, 220, and 311 faces in X-ray diffraction (XRD) of a mirror-finished cross section. Is divided by the value described on the ICDD card, and the peak intensity on the 111 plane is normalized so that the sum of the peak intensity on each plane is 1. Specifically, when the peak intensities of the 111, 200, 220, and 311 surfaces are I (111), I (200), I (220), and I (311), respectively. , [{I (111) / 100} / {I (111) / 100 + I (200) / 47} + I (220) / 22 + I (311) / 24]. The peak intensity is measured on a mirror-finished cross section.
The ICDD card is an X-ray diffraction database provided by International Center for Diffraction Data (ICDD). When the crystal grain size is large and the peak is cracked in normal XRD measurement, it is difficult to evaluate the degree of orientation. Using 2D (Two Dimensional) -XRD, the peak intensity of each X-ray diffraction is integrated. You may evaluate.

(Average crystal grain size)
The average crystal grain size is 70 μm or less. As described above, since the crystal grain size is small, there are few coarse crystal grains, high strength and heat resistance, and excellent compressibility. In particular, when compressed and deformed in the longitudinal direction, cracks and wrinkles hardly occur, and the above-described limit compression rate and surface roughness are satisfied. A more preferable average crystal grain size is 50 μm or less, further 40 μm or less, further 30 μm or less, particularly 25 μm or less, and more particularly 20 μm or less. The average crystal grain size is measured as follows. Twenty points P _n (n = 1 to 20) are equally spaced on the outer periphery of the cross section, and a point Q _n (n = 1 to 20) that internally divides a line segment OP _n connecting the center O and the point P _n. ). At the point Q _n , OQ _n : Q _n P _n is set to 3: 1. Then, a region of 1/8 of the length of the line segment OP _n is set around the point Q _n , the crystal grain size in all regions is measured, and the average value is taken as the average crystal grain size.
Note that the crystal grain size is analyzed using electron backscatter diffraction (EBSD), and a region surrounded by a crystal grain boundary having a bond angle of 5 ° or more is regarded as a crystal grain.

(Degree of variation in crystal grain size)
It is mentioned that the variation degree of the crystal grain size is 0.5 or less. As described above, since the variation in crystal grain size is small and the crystal grain size is uniform, it has high strength and heat resistance and is excellent in compression workability. In particular, when compressed and deformed in the longitudinal direction, cracks and wrinkles hardly occur, and the above-described limit compression rate and surface roughness are satisfied. A more preferable variation degree of the crystal grain size is 0.4 or less, and further 0.3 or less. The degree of variation in crystal grain size is measured as follows. Twenty points P _n (n = 1 to 20) are equally spaced on the outer periphery of the cross section, and points R _n (n = 1) having a depth of 0.5 mm from P _n toward the center O of the cross section. ~ 20). Then, a region of 1/8 of the length of the line segment OP _n is set around the point R _n , the crystal grain size in all regions is measured, and the standard deviation of the crystal grain size and the average crystal grain size are obtained, [(Standard deviation of crystal grain size) / (average crystal grain size)] is defined as the degree of variation in crystal grain size.
Note that the crystal grain size is analyzed using electron backscatter diffraction (EBSD), and a region surrounded by a crystal grain boundary having a bond angle of 5 ° or more is regarded as a crystal grain.

[Aluminum alloy wire manufacturing method]
The manufacturing method of an aluminum alloy wire typically includes a casting process, a rolling process, and a wire drawing process, and performs a specific wire drawing process in the wire drawing process. Details of each step are as follows.

<Casting process>
The casting process is a process of continuously casting an aluminum alloy having the above composition to obtain a cast material. Since continuous casting can be rapidly solidified, the generation of crystallized substances can be suppressed and the generation of coarse crystallized substances can be reduced. Accordingly, it is possible to suppress a decrease in workability due to coarse crystallized products. Further, the coarsening of crystal grains can be suppressed by rapid solidification, and a cast material having a fine crystal structure or a cast material having a high ratio of equiaxed crystals per unit cross-sectional area can be obtained. Also from this point, it is possible to suppress a decrease in workability at the time of plastic working performed after casting, and it is possible to manufacture an aluminum alloy wire having good workability. Furthermore, by reducing the coarse crystallized product, the additive element can be sufficiently dissolved by the solution treatment, and the desired precipitate can be formed satisfactorily and uniformly by the subsequent aging treatment. As a result, an effect of improving the strength by precipitation hardening can be obtained satisfactorily, and an aluminum alloy wire having high strength and heat resistance, and an aluminum alloy member excellent in strength and heat resistance can be produced. For the continuous casting, a known moving mold type continuous casting method such as a belt-and-wheel method or a Properti method can be used.

  Specific control conditions for rapid solidification include, for example, setting the solidification rate in the casting process to 1 ° C./second or more. As the solidification rate is increased, generation of crystallized substances can be suppressed, and coarse crystallized substances can be more effectively reduced. The solidification rate can be 2 ° C./second or more, 5 ° C./second or more, 8 ° C./second or more, 10 ° C./second or more. More preferably, the solidification rate is 1 ° C./second or more at an arbitrary position of the molten metal in the cooling process, that is, the entire molten metal is uniformly cooled. By doing so, it is easy to suppress the non-uniformity of the components accompanying the non-uniform solidification state, and plastic processing such as rolling can be satisfactorily performed after casting even if the homogenization treatment is unnecessary. In addition, since the solidification rate is fast (because it is high speed), Fe can be dissolved in supersaturation. Such a solidification rate can be realized, for example, by using a continuous casting machine having a water-cooled copper mold, a forced water-cooling mechanism, or the like. For example, if the mold temperature is lowered, the solidification rate can be increased. Other parameters for adjusting the solidification speed include the size of the cast material (cross-sectional area), the temperature of the molten metal, the casting speed, the amount of cooling water, and the material and surface roughness of the mold (grooved wheel, belt, dam block, etc.). It is done.

  The solidification rate is [(casting temperature−liquidus temperature of aluminum alloy) / (time required for solidification after casting)]. The time required for solidification from casting can be measured, for example, by attaching a thermocouple to the inner wall of a mold (for example, a belt) provided in a continuous casting machine and measuring the temperature change from the casting temperature to the liquidus temperature. it can. The liquidus temperature can be obtained in advance from the composition of the aluminum alloy.

  By performing rapid solidification by continuous casting, a cast material having a fine crystal structure can be obtained. By using this cast material as a raw material, it is possible to reduce the occurrence of cracks, wrinkles and wrinkles when rolling or wire drawing after casting, and a rolled material or wire drawing material with excellent surface properties can be obtained. Thus, an aluminum alloy wire excellent in surface properties can be obtained. Furthermore, when an aluminum alloy wire is forged, generation of cracks, wrinkles and wrinkles can be reduced, and an aluminum alloy member having excellent surface properties can be obtained. Therefore, by continuous casting, a long cast material having excellent surface properties can be mass-produced, and as a result, it can contribute to mass production of aluminum alloy wires having excellent surface properties and to improving the yield of aluminum alloy members.

<Rolling process>
A rolling process is a process of rolling the cast material into a rolled material. This rolling process is preferably performed hot or warm. Moreover, it is preferable to perform rolling continuously with casting. In the case of continuous casting and rolling in which casting and rolling are performed continuously, hot rolling or the like can be easily performed using heat accumulated in the cast material, and energy-efficient and mass-produced cast and rolled material can be produced. For example, a belt-and-wheel casting machine and a rolling machine connected to the casting machine are used. As such an apparatus, for example, a Properti type continuous casting and rolling mill can be used.

In a rolling process, it is preferable to adjust rolling conditions so that the crystallization thing which may be produced | generated by the said casting process is parted. For example, the Z factor during rolling may be 1.0 × 10 ¹⁰ or more and 1.0 × 10 ¹⁹ or less. Z factor (Z) at the time of rolling is ε (strain rate, / sec), Q (active energy of aluminum, J / mol), R (gas constant, J / (K × mol)), T (absolute temperature) , K), Z = ε × exp (Q / RT). By setting the Z factor to 1.0 × 10 ¹⁰ or more, even when a coarse crystallized product (for example, about 10 μm to 50 μm) is generated, it can be divided and refined. As a result, it is possible to suppress a decrease in workability due to coarse crystallized products. Therefore, an aluminum alloy wire can be manufactured satisfactorily. Moreover, it contributes to the improvement of tensile strength by reducing coarse crystallized substances. A more preferable range of the Z factor is 1.0 × 10 ¹² or more and 1.0 × 10 ¹⁷ or less. Industrially, the Z factor can be adjusted by the linear velocity during rolling and the rolling temperature (T). Although it depends on the size (cross-sectional area) and composition of the object to be rolled, for example, the linear velocity is 5 cm / second or more and 50 cm / second or less, and the rolling temperature is 300 ° C. or more and 550 ° C. or less.

<Wire drawing process>
The wire drawing step is a step of drawing the rolled material into a wire drawing material. The wire drawing is performed until a predetermined wire diameter is obtained. This wire drawing is typically performed cold. Peeling can be performed according to the surface state of the rolled material before wire drawing. A wire drawing die can be used for wire drawing.

The wire drawing step includes continuous wire drawing until the degree of processing reaches 30% or more and 90% or less. By performing at least one set of continuous wire drawing until the degree of work reaches 30% or more and 90% or less in the wire drawing process, the texture of the cross section can be controlled to be oriented in the 111 plane and high strength. The above-mentioned aluminum alloy wire having excellent heat resistance can be produced. The continuous wire drawing means that heat treatment at, for example, 300 ° C. or higher is not performed during the wire drawing, and the continuous wire drawing includes one wire drawing. The degree of continuous wire drawing is the total degree of drawing when the wire drawing is continuously performed a plurality of times. When the above heat treatment is performed in a state where the degree of processing is less than 30%, the strain introduced by the processing is released, so that it is difficult to orient the 111 plane, and the 111 plane is insufficiently oriented. On the other hand, if the wire drawing is continuously performed until the degree of processing becomes 30% or more, the orientation of the 111 plane becomes strong, and even after heat treatment such as intermediate softening treatment described later, it was introduced by the processing. The orientation of the 111 plane is maintained. The degree of processing is a value represented by a cross-section reduction rate (%), where A _{0 is} a cross-sectional area before wire drawing and A is a cross-sectional area after wire drawing [(A ₀ -A) / A ₀ × 100]. The degree of continuous wire drawing can be 40% or more, more than 60%, 65% or more, 70% or more, or 75% or more. There is a tendency that the degree of orientation of the 111 plane increases as the degree of continuous wire drawing increases. In addition, the higher the degree of continuous wire drawing, the finer and more uniform the crystal structure can be made.

<Others>
The following heat treatment (softening treatment) can be appropriately performed during the manufacturing process.

(WR softening treatment)
After the rolling step, before the wire drawing step, the rolled material (wire rod) can be softened. By performing the WR softening treatment, the non-uniform distortion introduced in the rolling process is removed, and a uniform structure is easily obtained in the wire drawing process. The WR softening treatment may be performed at a temperature lower than 450 ° C. for 1 hour to 100 hours. The temperature of the WR softening treatment is preferably 300 ° C. or higher, more preferably 350 ° C. or higher and lower than 420 ° C., further preferably 400 ° C. or lower. The atmosphere of the WR softening treatment may be a non-oxidizing atmosphere (such as a reduced pressure atmosphere, an inert gas atmosphere, or a reducing gas atmosphere).

(Intermediate softening treatment)
An intermediate softening process can be performed during the wire drawing process (specifically, after the continuous wire drawing process described above). By performing the intermediate softening treatment, the crystal structure can be refined and the wire drawing workability can be improved. The intermediate softening treatment may be performed at a temperature lower than 450 ° C. for 1 hour to 100 hours. The temperature of the intermediate softening treatment is preferably 300 ° C. or higher, more preferably 350 ° C. or higher and lower than 420 ° C., further preferably 400 ° C. or lower. The atmosphere of the intermediate softening treatment may be, for example, a non-oxidizing atmosphere (such as a reduced pressure atmosphere, an inert gas atmosphere, a reducing gas atmosphere).

  Further, by performing the wire drawing after the intermediate softening treatment, the straightness of the wire can be improved and the strength of the wire can be increased by work hardening. The degree of drawing of the wire drawing after the intermediate softening treatment is, for example, less than 20%. If the degree of drawing of the wire drawing after the intermediate softening treatment is less than 20%, the strain accumulated in the wire is finally reduced, so that it is easy to ensure the workability of the wire. The degree of processing in this case is determined based on the wire diameter (cross-sectional area) of the wire after the intermediate softening treatment.

(Final softening treatment)
Softening treatment can be performed after the final wire drawing. By performing the final softening treatment, the strain introduced by the processing is removed and softened, so that it becomes easy to process the aluminum alloy wire into the aluminum alloy member. For example, the final softening treatment may be performed at less than 450 ° C. for 1 hour or longer. The temperature of the final softening treatment is preferably 300 ° C. or higher, more preferably 350 ° C. or higher. As the atmosphere of the final softening treatment, for example, a non-oxidizing atmosphere (a reduced pressure atmosphere, an inert gas atmosphere, a reducing gas atmosphere, or the like) can be cited.

(Solution treatment / aging treatment)
Further, in the final step after the wire drawing step, the wire drawing material can be subjected to a solution treatment or an aging treatment after the solution treatment. For example, the solution treatment is 550 ° C. or more and 580 ° C. or less × 15 minutes or more and 120 minutes or less, and the aging treatment is 160 ° C. or more and 180 ° C. or less × 4 hours or more and 8 hours or less. This solution treatment and aging treatment may be performed during the manufacturing process of the aluminum alloy member.

[Aluminum alloy members]
The aluminum alloy member is obtained by processing the above-described aluminum alloy wire having high strength and heat resistance as a raw material. Therefore, since it has high strength and excellent heat resistance, it is suitable as a member that is lightweight and requires high strength and heat resistance. For example, an aluminum alloy member subjected to solution treatment and aging treatment has a tensile strength of 400 MPa or more, and satisfies a tensile strength of 370 MPa or more in a heat resistance test at 150 ° C. for 1000 hours. Examples of the aluminum alloy member include automotive parts such as a spool valve in addition to fastening members such as bolts and rivets.

  An example of a bolt manufacturing process will be described. First, after cutting an aluminum alloy wire to a predetermined length, a bolt head portion is formed by forging. Then, after the solution treatment and the aging treatment, the thread groove is formed by rolling. The mechanical properties of the bolt can be measured by a tensile test using the bolt as a test piece in accordance with JIS B 1051 (2000).

[Test Example 1]
Aluminum alloy wires having various compositions shown in Table 1 were produced and evaluated. In this test, an aluminum alloy wire is manufactured by a process of casting → rolling → drawing. Table 1 shows only the additive element and its content (mass%), and the balance is Al and inevitable impurities. In addition, “(excess Si + Fe) / Mn” shown in Table 1 is the above-mentioned [{(excess Si amount) + (Fe content)} / (Mn content)]. (Equation 1).

<Manufacture of aluminum alloy wire>
Pure aluminum as a base is melted (here, 700 ° C. or more and 750 ° C. or less), and the additive element is added to the molten metal so as to have a predetermined concentration shown in Table 1, and is sufficiently held (here, 10 hours or more) ). The molten aluminum alloy whose components are adjusted is appropriately subjected to a hydrogen gas removal treatment or a foreign matter removal treatment. Using the produced aluminum alloy melt, casting and hot rolling are continuously performed by a Properti type continuous casting rolling mill equipped with a belt-and-wheel type continuous casting machine, and then a wire rod (here, diameter φ12 mm continuous casting). Rolled material). The solidification rate during casting is 5 ° C./second. Here, casting is performed using a water-cooled copper mold so that the solidification rate is 5 ° C./second at an arbitrary position of the molten metal in the cooling process. Further, the rolling is performed by adjusting the linear velocity and the rolling temperature so that the Z factor of the rolling process is 1.9 × 10 ¹⁶ . Subsequently, the wire rod is drawn cold to produce a wire drawing material (round wire). Here, WR softening treatment was performed at 400 ° C. for 10 hours in a reducing gas atmosphere before wire drawing, and intermediate softening treatment was performed at 400 ° C. for 10 hours in a reducing gas atmosphere during wire drawing. In addition, continuous wire drawing from the start of wire drawing to intermediate softening is primary wire drawing, and after intermediate softening treatment, continuous wire drawing from final wire drawing to secondary wire drawing is secondary wire drawing. The working degree of the wire was 30%, and the working degree of the secondary wire drawing was 15%. As described above, sample No. 1-1-1-6 aluminum alloy wires were obtained. The composition of the obtained aluminum alloy wire is the same as that shown in Table 1. A known method can be used for the composition analysis of the aluminum alloy wire. For example, an energy dispersive X-ray analyzer can be used.

<Evaluation of aluminum alloy wire>
About the obtained aluminum alloy wire, structure | tissue, tensile strength, and compression workability were evaluated.

(Organization)
The structure was evaluated by measuring the degree of orientation of the 111 plane, the average crystal grain size, and the variation in crystal grain size. The degree of orientation of the 111 plane, the average crystal grain size, and the degree of variation of the crystal grain size are described in the respective sections of (111 plane orientation degree), (average crystal grain size), and (crystal grain size variation degree). Measured based on the measurement method. The results are shown in Table 2.

(Tensile strength)
The tensile strength was measured according to JIS Z 2241 (2011). After preparing a test piece for a tensile test from an aluminum alloy wire and subjecting the test piece to solution treatment at 550 ° C., the tensile strength (first tensile strength) after further aging treatment at 170 ° C. × 8 hours The tensile strength (second tensile strength) after the heat treatment at 150 ° C. for 1000 hours was measured after the solution treatment and the aging treatment. Furthermore, the maintenance rate of the second tensile strength relative to the first tensile strength was also determined. The maintenance ratio (%) of the tensile strength was obtained as [("second tensile strength" / "first tensile strength") x 100]. The results are shown in Table 2.

(Compression processability)
The compression workability was evaluated with respect to the limit compression rate, the degree of compression deformation, and the surface roughness of the side surface after compression deformation. The critical compression ratio was measured based on the measurement method described in the above section (Limit compression ratio) by preparing a test piece having an aspect ratio of 1: 2 from an aluminum alloy wire. The degree of compressive deformation was measured on the basis of the measurement method described in the above section (degree of compressive deformation) using a test piece having an aspect ratio of 1: 2 made from an aluminum alloy wire. And when the degree of compressive deformation when the test piece is 40%, 30% and 20% of the original length, respectively, is 0.1 or less, “outer shape: circular”, and other cases are “ “Outer shape: non-circular”. The surface roughness of the side surface is obtained by preparing a test piece having an aspect ratio of 1: 2 from an aluminum alloy wire, and using this test piece, the arithmetic average roughness is based on the measurement method described in the above section (Limit compression ratio). Ra was measured. Then, the case where the maximum value of the arithmetic average roughness Ra of the measured side surface is 0.5 mm or less is “皺: none”, and the case where it is other than that (that is, the Ra maximum value> 0.5) is “皺: yes”. It was. The results are shown in Table 2.

  As shown in Table 2, sample no. 1-1 to 1-6 have a first tensile strength of 400 MPa or more and a second tensile strength of 370 MPa or more, and have high strength and heat resistance. Sample No. 1-1 to 1-6 satisfy a limit compression ratio of 85% or more, and are not only difficult to crack even when compressed and deformed, but also less likely to wrinkle when compressed and deformed. Furthermore, since the outer shape seen from the compression direction is easily deformed into a circular shape when compressed and deformed, it has good compressibility. And sample no. 1-1 to 1-6, the degree of orientation of the 111 plane satisfies 0.5 or more, the texture of the cross section is strongly oriented to the 111 plane, and the average crystal grain size is 70 μm or less (particularly 25 μm or less). The degree of variation in crystal grain size is 0.5 or less, and it has a fine and homogeneous crystal structure.

[Test Example 2]
Except for changing the solidification rate at the time of casting, the sample No. Aluminum alloy wires (sample Nos. 2-1 to 2-4) having the same composition as 1-1 were produced. Table 3 shows the solidification rate during casting of each sample. Moreover, it carried out similarly to Test Example 1, and evaluated the structure | tissue, tensile strength, and compression workability about the obtained aluminum alloy wire. The results are also shown in Table 3.

  As shown in Table 3, sample Nos. With a solidification rate of 1 ° C./second or more were used. 1-1 and Sample No. 2-1 and 2-2 have high strength and heat resistance, and are excellent in compression workability. Sample No. 1-1 and Sample No. 2-1 and 2-2 have a 111-plane orientation degree of 0.5 or more and have a fine and homogeneous crystal structure. On the other hand, Sample No. with a solidification rate of 0.05 ° C./second or less. 2-3 and 2-4 were not evaluated because wire breakage occurred during wire drawing. This is thought to be because the solidification rate is slow, so that coarse crystallized substances are generated during casting, and the workability of the wire rod as the material is lowered.

[Test Example 3]
By changing the manufacturing conditions, the sample No. An aluminum alloy wire having the same composition as 1-1 (Sample Nos. 3-1 to 3-37) was produced. The production conditions for each sample are shown in Tables 4 and 5. Further, in the same manner as in Test Example 1, the obtained aluminum alloy wire was evaluated for the structure, tensile strength, and compressibility. The results are also shown in Tables 4 and 5.

  Sample No. In 3-1 to 3-9, the production conditions were the same as in Test Example 1 except that the temperature of the WR softening treatment and the intermediate softening treatment was 420 ° C., and the degree of primary wire drawing was changed. However, sample No. In 3-7 and 3-9, the temperature of the WR softening treatment and the intermediate softening treatment was 380 ° C., respectively, and the degree of processing of secondary wire drawing was 7%.

Sample No. In 3-10 to 3-18, the temperature of the intermediate softening treatment was set to 420 ° C., the wire drawing was performed without performing the WR softening treatment, and the degree of primary drawing was changed. However, sample No. In 3-12 , 3-15 , 3-17, and 3-18 , the temperature of the intermediate softening treatment was set to 380 ° C., and the workability of the secondary wire drawing was set to 7%.

  Sample No. In Nos. 3-19 to 3-23, the temperature of the WR softening treatment was 380 ° C., the working degrees of the primary wire drawing and the secondary wire drawing were 40% and 7%, and the temperature of the intermediate softening treatment was changed.

  Sample No. In 3-24 to 3-27, the temperature of the WR softening treatment was changed by setting the temperature of the intermediate softening treatment to 380 ° C., the working degrees of the primary wire drawing and the secondary wire drawing to 40% and 15%, respectively.

  Sample No. In Nos. 3-28 to 3-30, the temperature of the WR softening process was set to 420 ° C., and the intermediate softening process was not performed in the middle of the wire drawing process, and the degree of continuous drawing was changed. However, in this case, since there is no distinction between primary wire drawing and secondary wire drawing, the total work degree of wire drawing is described in the column of “Primary wire drawing degree” in Table 4.

  Sample No. For 3-3-1 to 3-33, the temperature of the WR softening treatment and the intermediate softening treatment was 380 ° C., the working degree of the primary wire drawing and the secondary wire drawing was 40% and 7%, respectively, and the time of the intermediate softening treatment was changed. . However, sample No. The production condition of 3-32 is Sample No. Same as 3-20.

  Sample No. In 3-34 to 3-36, the temperature of the WR softening treatment and the intermediate softening treatment were set to 380 ° C., the primary wire drawing and the secondary wire drawing were processed to 40% and 7%, respectively, and the time of the WR softening treatment was changed. . However, sample No. The production condition of 3-35 is Sample No. Same as 3-20.

  Sample No. 3-37 was made into the same manufacturing conditions as Test Example 1 except having changed the degree of processing of primary wire drawing and secondary wire drawing, respectively.

  As shown in Table 4, Sample No. with a processing degree of continuous wire drawing (primary wire drawing) of 30% or more was used. 3-2 to 3-9 have high strength and heat resistance, and are excellent in compression processability. Sample No. 3-2 to 3-9 have a 111-plane orientation degree of 0.5 or more, and have a fine and homogeneous crystal structure. From the comparison results of these samples, the higher the degree of continuous wire drawing, the higher the tensile strength, the higher the degree of orientation of the 111 plane, and the tendency to have a fine and homogeneous crystal structure. I understand that.

  Furthermore, sample no. 3-1 to 3-9 and Sample No. From comparison with 3-10 to 3-18, it can be seen that even when WR softening treatment is not performed, properties such as strength, heat resistance and compression workability are good. Rather, the sample No. not subjected to WR softening treatment. Sample Nos. 3-10 to 3-18 were subjected to WR softening treatment. Compared with 3-1 to 3-9, the characteristics are slightly improved, the degree of orientation of the 111 plane is increased, and the crystal structure tends to be refined and homogenized. This is presumably because the WR softening treatment was not performed, so that the processing strain introduced by the rolling process was maintained, and the orientation to the 111 plane by the wire drawing process was performed efficiently.

  As shown in Table 4, the sample No. 1 was set so that the temperature of the intermediate softening treatment was less than 450 ° C. 3-19 to 3-22 have good characteristics, and the degree of orientation of the 111 plane also satisfies 0.5 or more. On the other hand, sample No. As in 3-23, when the temperature of the intermediate softening treatment is set to 450 ° C. or higher, mechanical properties (tensile strength) and compression workability are deteriorated. In addition, from the comparison of these samples, by setting the temperature of the intermediate softening treatment to less than 450 ° C., it is easy to orient in the 111 plane, and it is easy to make crystal grains finer or suppress variations in crystal grain size. I understand.

  Furthermore, the sample Nos. Shown in Table 5 were used. From the results of 3-31 to 3-33, it can be seen that the characteristics are hardly affected if the time of the intermediate softening treatment is in the range of 1 hour to 100 hours.

  As shown in Table 4, the sample No. 1 was adjusted so that the temperature of the WR softening treatment was less than 450 ° C. 3-24 to 3-26 have good characteristics, and the degree of orientation of the 111 plane also satisfies 0.5 or more. On the other hand, sample No. As in 3-27, when the temperature of the WR softening treatment is set to 450 ° C. or higher, mechanical properties (tensile strength) and compression workability are deteriorated. In addition, by comparing these samples, by setting the temperature of the WR softening treatment to less than 450 ° C., it is easy to orient in the 111 plane, and it is easy to make crystal grains finer or suppress variations in crystal grain size. I understand.

  Furthermore, the sample Nos. Shown in Table 5 were used. From the results of 3-34 to 3-36, it can be seen that when the WR softening time is in the range of 1 hour to 100 hours, the characteristics are hardly affected.

  As shown in Table 5, sample no. From the comparison results of 3-28 to 3-30, it is understood that sufficient characteristics can be obtained by setting the degree of continuous wire drawing to 30% or more even when the intermediate softening treatment is not performed. . In this case, the compressibility (particularly, the limit compression ratio) is slightly lowered, but the heat resistance tends to be slightly improved.

  Furthermore, sample no. 3-2 and 3-29 and sample no. From the comparison result with 3-37, even if the total degree of drawing (working degree of primary drawing and secondary drawing) is 30% or more, the degree of continuous drawing work is When it is less than 30%, the second tensile strength is low, and it does not have sufficient heat resistance. In addition, the orientation of the 111 plane is insufficient, and the compression processability is poor.

  The aluminum alloy wire of the present invention can be used as a material for various aluminum alloy members. In particular, it can be suitably used as a material for aluminum alloy members that are lightweight and require high strength and heat resistance. The aluminum alloy member of the present invention can be used for, for example, fastening members such as bolts and rivets, and automotive parts such as spool valves. The method for producing an aluminum alloy wire of the present invention can be used for producing an aluminum alloy wire.

Claims (10)

In mass%, Si: 0.9% to 1.3%, Mg: 0.8% to 1.2%, Fe: 0% to 0.4%, Cu: 0.65% to 1. 1% or less, Mn: 0.55% to 1.15%, Cr: 0% to 0.35%, Zn: 0.12% to 0.25%, Ti: 0% to 0.075% hereinafter, Zr: including 0.05% or more 0.17% or less, Ri balance Al and unavoidable impurities der,
[{(Excess Si amount) + (Fe content)} / (Mn content)], which is the ratio of the sum of the excess Si amount and the Fe content and the Mn content, is 0.5 or more. Having a composition satisfying 1.8 or less ,
An aluminum alloy wire having the following physical properties (1) to (5) and structures (A) to (C) .
(1) After the solution treatment at 550 ° C., the tensile strength after further aging treatment at 170 ° C. × 8 hours is 400 MPa or more.
(2) After the aging treatment, the tensile strength after a heat resistance test at 150 ° C. × 1000 hours is 370 MPa or more.
(3) The critical compression ratio when compressed and deformed in the longitudinal direction is 80% or more.
(4) The degree of compressive deformation when compressed and deformed to 40%, 30%, and 20% of the original length in the longitudinal direction respectively is 0.1 or less
(5) The maximum value of the arithmetic mean roughness Ra of the side surface is 0.5 mm or less when compressed and deformed to 15% of the original length in the longitudinal direction.
(A) 111 plane orientation degree in X-ray diffraction of cross section is 0.5 or more
(B) Average crystal grain size is 70 μm or less
(C) The degree of variation in crystal grain size is 0.5 or less The content of each element in the composition is mass%,
Si: 0.9% or more and 1.2% or less,
Mg: 0.8% or more and 1.0% or less,
Fe: 0% to 0.25%,
Cu: 0.65% or more and 0.85% or less,
Mn: 0.55% or more and 0.65% or less,
Cr: 0% or more and 0.05% or less,
Zn: 0.15% or more and 0.25% or less,
Ti: 0% or more and 0.05% or less,
The aluminum alloy wire according to claim 1 , wherein Zr is 0.11% or more and 0.17% or less. The aluminum alloy wire according to claim 1 or 2 , wherein the tensile strength after the heat test is 85% or more of the tensile strength after the aging treatment. In mass%, Si: 0.9% to 1.3%, Mg: 0.8% to 1.2%, Fe: 0% to 0.4%, Cu: 0.65% to 1. 1% or less, Mn: 0.55% to 1.15%, Cr: 0% to 0.35%, Zn: 0.12% to 0.25%, Ti: 0% to 0.075% hereinafter, Zr: including 0.05% or more 0.17% or less, Ri balance Al and unavoidable impurities der,
[{(Excess Si amount) + (Fe content)} / (Mn content)], which is the ratio of the sum of the excess Si amount and the Fe content and the Mn content, is 0.5 or more. A casting process of continuously casting an aluminum alloy having a composition satisfying 1.8 or less to obtain a cast material;
A rolling step of rolling the cast material to obtain a rolled material;
A wire drawing step of drawing the rolled material into a wire drawing material having a predetermined wire diameter,
In the casting process, the solidification rate is 1 ° C./second or more,
In the wire drawing step, viewed it contains a continuous wire drawing process until the working ratio is 30% or more 90% or less,
The manufacturing method of the aluminum alloy wire which the aluminum alloy wire manufactured through said process has the physical property of following (1)-(5), and the structure | tissue of (A)-(C) .
(1) After the solution treatment at 550 ° C., the tensile strength after further aging treatment at 170 ° C. × 8 hours is 400 MPa or more.
(2) After the aging treatment, the tensile strength after a heat resistance test at 150 ° C. × 1000 hours is 370 MPa or more.
(3) The critical compression ratio when compressed and deformed in the longitudinal direction is 80% or more.
(4) The degree of compressive deformation when compressed and deformed to 40%, 30%, and 20% of the original length in the longitudinal direction respectively is 0.1 or less
(5) The maximum value of the arithmetic mean roughness Ra of the side surface is 0.5 mm or less when compressed and deformed to 15% of the original length in the longitudinal direction.
(A) 111 plane orientation degree in X-ray diffraction of cross section is 0.5 or more
(B) Average crystal grain size is 70 μm or less
(C) The degree of variation in crystal grain size is 0.5 or less The content of each element in the composition is mass%,
  Si: 0.9% or more and 1.2% or less,
  Mg: 0.8% or more and 1.0% or less,
  Fe: 0% to 0.25%,
  Cu: 0.65% or more and 0.85% or less,
  Mn: 0.55% or more and 0.65% or less,
  Cr: 0% or more and 0.05% or less,
  Zn: 0.15% or more and 0.25% or less,
  Ti: 0% or more and 0.05% or less,
  The method for producing an aluminum alloy wire according to claim 4, wherein Zr is 0.11% or more and 0.17% or less. 6. The method for producing an aluminum alloy wire according to claim 4 , wherein, in the wire drawing step, an intermediate softening treatment is performed at less than 450 ° C. for 1 hour to 100 hours after the continuous wire drawing. The method for producing an aluminum alloy wire according to any one of claims 4 to 6 , wherein after the rolling step and before the wire drawing step, a softening treatment is performed at less than 450 ° C for 1 hour to 100 hours. An aluminum alloy member obtained by processing the aluminum alloy wire according to any one of claims 1 to 3 . The aluminum alloy member according to claim 8 , which is a bolt. The aluminum alloy member according to claim 8 , which is an automotive part.