JP2017133097A - Mechanical member and manufacturing method and extrusion material - Google Patents
Mechanical member and manufacturing method and extrusion material Download PDFInfo
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Abstract
Description
本発明は機械部品およびその製造方法、押出材に関するものである。本発明で言う機械部品とは、押出材を素材とする、ボルトおよびナット等のねじ部品、歯車（ギア）、軸（シャフト）、軸受け（ベアリング）、ばね（スプリング）などの、様々な機械に共通して使われている最小単位の機能部品としての機械要素である。 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.
従来から、ボルトおよびナットのねじ部品、ならびにばね（スプリング）などの様々な機械部品用の素材として、強度、耐食性および軽量性に優れた素材（材料）として、Ａｌ−Ｚｎ−Ｍｇ−Ｃｕ系である７０００系アルミニウム合金からなる、断面が円形な線状あるいは棒状の押出材が用いられている。 Conventionally, as a material for various mechanical parts such as bolts and nuts, and various mechanical parts such as springs, as a material (material) excellent in strength, corrosion resistance and light weight, Al-Zn-Mg-Cu system is used. A linear or rod-like extruded material made of a certain 7000 series aluminum alloy and having a circular cross section is used.
前記７０００系アルミニウム合金からなる押出材は高強度であり、押出後にＴ６調質することで、引張強さが７００ＭＰａ以上のものも、従来から種々提案されている。 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 proposed in the past by performing T6 refining after extrusion.
例えば、特許文献１では、Ｚｎ含有量が８質量％を超えるような７０００系アルミニウム合金の線棒押出材につき、時効処理により容易に引張強さ７２０ＭＰａを超える強度が付与できることが開示されている。しかし、同文献に係る押出材では、粗大な再結晶粒層が必然的に生じるので、押出材を大径ボルトに鍛造または転造などの塑性加工（成形加工）する際に、割れが発生する原因となる。このため、塑性加工前に押出材表面（表層部）の粗大な再結晶粒層を除去することを必須としている。 For example, Patent Document 1 discloses that a wire rod extruded material of a 7000 series aluminum alloy having a Zn content exceeding 8% by mass can easily be provided 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.
これに対して、このような再結晶粒層自体を抑制しようとする試みも、従来から種々提案されている。例えば、特許文献２では、押出温度を４８０〜５００℃の比較的低温として、７０００系アルミニウム合金押出材内部を繊維状組織とし、表層の再結晶層の肉厚を１０％以下とし、その再結晶粒径を１５０μｍ以下に制御することが開示されている。
しかし、特許文献２のように、押出温度を４８０〜５００℃の比較的低温としても、この温度域の押出では、やはり７０００系アルミニウム合金は再結晶してしまう。そのため、押出材の表層部および内部における再結晶化が避けがたく、再現性よく、引張強さで７００ＭＰａ以上の強度を得ることができない可能性があった。
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 a fibrous structure, the thickness of the recrystallized layer on the surface layer is 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 in the 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.
特許文献３では、熱間静水圧押出によって７０００系アルミニウム合金押出材を製造することが開示されている。当該押出材は、押出されたままの状態での、押出材の軸中心部を通る押出方向に平行な断面の組織として、押出材の表層部の再結晶粒の平均結晶粒径が１００μｍ以下であるとともに、押出材軸中心部における結晶粒の半径方向の平均切片長さが３５μｍ以下であり、かつ、押出方向の＜１１１＞方位の結晶粒の平均面積率が０．５以上１．０以下で、＜００１＞方位の結晶粒の平均面積率と＜１１１＞方位の結晶粒の平均面積率との比、＜００１＞／＜１１１＞が０．２５以下であることが開示されている。
特許文献３では、これによって、熱間押出終了後に、押出温度からの冷却以外は、組織が変化する熱処理および加工を何も加えていない、押出されたまま(押出上がり)の押出材の組織状態として、表層部だけでなく押出材内部の再結晶（再結晶化）も抑制している。これにより微細な押出加工組織（繊維状組織）を得て、人工時効処理後の引張強さで７００ＭＰａ以上の高強度を得ることが開示されている。
しかし、特許文献３では、その実施例の表３の通り、得られる人工時効処理後の引張強さは７００ＭＰａ以上ではあるが、８００ＭＰａ未満程度でしかない。
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.
また、特許文献４では、押出材では無く、フレームおよびピラーなどの自動車構造部材用の７０００系アルミニウム合金圧延板が開示されている。同文献では、高強度化させるために、この圧延板の結晶方位組織として、平均結晶粒径が１５μｍ以下であるとともに、傾角５〜１５°の小傾角粒界の平均割合を１５％以上、かつ傾角１５°を超える大傾角粒界の平均割合を１５〜５０％とすることが開示されている。
しかし、この特許文献４の場合、その実施例の表２の通り、得られる人工時効処理後の引張強さは５００ＭＰａ未満であり、圧延板でのこのような冶金的手法が、塑性加工方法および製造方法が異なる押出材および機械部品の８００ＭＰａ以上の高強度化に有効かどうかは、実際に試験して確かめてみないと分らない。
Patent Document 4 discloses a 7000 series aluminum alloy rolled plate for automobile structural members such as frames and pillars, not extruded materials. In the same document, in order to increase the strength, as the crystal orientation structure of the rolled sheet, the average crystal grain size is 15 μm or less, and the average proportion of the low-angle grain boundaries with an inclination of 5 to 15 ° is 15% or more, and It is disclosed that the average proportion of the large-angle grain boundaries exceeding the tilt angle of 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.
このように、従来の７０００系アルミニウム合金押出材は、前記機械部品用あるいは機械要素用の素材として、合金量を増やして耐ＳＣＣ性および耐粒界腐食感受性などの耐食性を低下させること無しに、人工時効処理後の前記機械部品としての引張強さ８００ＭＰａ以上の高強度を安定して得ることは難しい課題であった。 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.
本発明はかかる問題に鑑みなされたもので、人工時効処理後の引張強さが８００ＭＰａ以上、全伸びが５％以上である高強度特性が得られる、７０００系アルミニウム合金押出材からなる前記機械部品およびその製造方法、押出材を提供することを目的とする。 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.
上記目的を達成するための、本発明の強度に優れた機械部品の要旨は、質量％で、Ｚｎ：８．０〜１４．０％、Ｍｇ：２．０〜４．０％、Ｃｕ：０．５〜２．０％、Ｍｎ：０．２〜１．５％、Ｚｒ：０．０５〜０．３％を各々含有し、残部がＡｌ及び不可避的不純物からなる７０００系アルミニウム合金の押出加工組織を有する機械部品であって、この機械部品の表面と軸中心との中間位置における前記押出加工方向に平行な面をＳＥＭ−ＥＢＳＤ法により測定した前記組織および特性として、傾角５〜１５°の小傾角粒界の平均割合が５％以上、傾角１５°を超える大傾角粒界の平均割合が２０％以上であるとともに、ＫＡＭ値の平均値が０．３°以上であり、引張強さが８００ＭＰａ以上、全伸びが５％以上であることとする。 The gist of the mechanical parts excellent in strength 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 Extrusion processing 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, wherein the surface parallel to the extrusion direction at an intermediate position between the surface of the machine part and the center of the axis is measured by the SEM-EBSD method, and the structure is characterized by an inclination 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.
また、上記目的を達成するための本発明の機械部品の製造方法の要旨は、質量％で、Ｚｎ：８．０〜１４．０％、Ｍｇ：２．０〜４．０％、Ｃｕ：０．５〜２．０％、Ｍｎ：０．２〜１．５％、Ｚｒ：０．０５〜０．３％を各々含有し、残部がＡｌ及び不可避的不純物からなる７０００系アルミニウム合金鋳塊を、均熱処理後に押出加工して押出材とし、この押出材を機械部品に加工した後に、溶体化および焼入れ処理を行い、更に人工時効処理を行って、この機械部品の表面と軸中心との中間位置における前記押出加工方向に平行な面をＳＥＭ−ＥＢＳＤ法により測定した組織および特性として、傾角５〜１５°の小傾角粒界の平均割合が５％以上、傾角１５°を超える大傾角粒界の平均割合が２０％以上であるとともに、ＫＡＭ値の平均値が０．３°以上である組織とし、この機械部品の引張強さを８００ＭＰａ以上、全伸びを５％以上とすることである。 Moreover, the summary of the manufacturing method of the mechanical component of this invention for achieving the said objective is the mass%, Zn: 8.0-14.0%, Mg: 2.0-4.0%, Cu: 0 A 7000 series aluminum alloy ingot containing 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 ratio of the small-angle grain boundaries having an inclination of 5 to 15 ° is 5% or more, and the large-angle boundaries exceeding 15 ° Average ratio of KAM value is 20% or more Is a structure having an angle of 0.3 ° or more, and the tensile strength of the mechanical part is 800 MPa or more and the total elongation is 5% or more.
更に、上記目的を達成するための本発明の押出材の要旨は、質量％で、Ｚｎ：８．０〜１４．０％、Ｍｇ：２．０〜４．０％、Ｃｕ：０．５〜２．０％、Ｍｎ：０．２〜１．５％、Ｚｒ：０．０５〜０．３％を各々含有し、残部がＡｌ及び不可避的不純物からなる７０００系アルミニウム合金の機械部品用押出材であって、この押出材を、機械部品を模擬して、断面が円形な直径２５ｍｍの線棒押出材とした上で、減面率が８４％で抽伸加工して１０ｍｍφの断面が円形な線棒材とし、この線棒材を４８０℃の温度で５時間保持する溶体化処理後に、５０℃までの平均冷却速度を２００℃/秒として焼入れ処理を行い、その後１２０℃で７２時間保持する人工時効処理を施した際の、この線棒材の表面と軸中心との中間位置における前記押出加工方向に平行な面をＳＥＭ−ＥＢＳＤ法により測定した組織および特性として、傾角５〜１５°の小傾角粒界の平均割合が５％以上、傾角１５°を超える大傾角粒界の平均割合が２０％以上であるとともに、ＫＡＭ値の平均値が０．３°以上であり、引張強さが８００ＭＰａ以上、全伸びが５％以上であることとする。 Furthermore, the summary 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: 0.2-1.5%, Zr: 0.05-0.3%, 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. When the aging treatment is performed, the extrusion process is performed at an intermediate position between the surface of the wire rod and the shaft center. As the structure and characteristics of a plane parallel to the direction measured by the SEM-EBSD method, the average ratio of small-angle grain boundaries with an inclination of 5 to 15 ° is 5% or more, and the average ratio of large-angle grains with an inclination of 15 ° is 20 %, 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.
本発明は、７０００系アルミニウム合金押出材からなる前記機械部品、すなわち、アルミニウム合金の押出微細組織を有する機械部品として、人工時効処理後のＳＥＭ−ＥＢＳＤ法により測定された結晶粒組織（結晶粒）の、小傾角粒界と大傾角粒界の平均割合と、平均方位差であるＫＡＭ値を制御する。
また、押出材（素材）の、前記機械部品を模擬した、特定の抽伸加工、溶体化処理、人工時効処理を施した際の、ＳＥＭ−ＥＢＳＤ法により測定された結晶粒組織（結晶粒）の、小傾角粒界と大傾角粒界の平均割合と、平均方位差であるＫＡＭ値を制御する。
なお、本発明で言う「人工時効処理後」とは、「溶体化および焼入れ処理と人工時効処理とを施した後」という意味である。
これによって、機械部品の特性、あるいはこの機械部品を模擬した押出材の特性として、引張強さが８００ＭＰａ以上、全伸びが５％以上の高強度化を図ることができる。
また、このような本発明の組織制御では、機械部品の耐ＳＣＣ性および耐粒界腐食感受性などの耐食性も低下させる恐れが無く、高強度化できる利点がある。
更に、押出材表層部（表面部）の再結晶粒層を抑制できれば、押出材表層部の再結晶粒層を除去することなく、前記機械部品の製品形状まで加工できる利点もある。
The present invention relates to the above-mentioned mechanical part made of an extruded material of 7000 series aluminum alloy, that is, a mechanical part having an extruded microstructure of an aluminum alloy, a grain structure (crystal grain) measured by an SEM-EBSD method after artificial aging treatment 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 grain 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 was 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.
In the present invention, “after artificial aging treatment” 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 invention has an advantage that the strength can be increased without fear of reducing 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.
以下に、本発明の実施の形態につき、順に要件ごとに具体的に説明する。
以下に説明するアルミニウム合金組成および組織は、機械部品あるいは押出材としての、共通する意義および個別の意義につき説明する。
なお、本発明の機械部品用の押出材（素材）は、線状あるいは棒状の押出材であり、その断面形状を、本発明では断面形状が円形と規定している。この断面形状が円形とは真円を意味するが、一方で、本発明は、このような真円でなくとも、楕円形や、最外径が円形状となるような、円形に近い断面形状を含むものある。
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 (raw material) for machine parts of this invention is a linear or rod-like extrusion material, and the cross-sectional shape is prescribed | regulated as circular in this invention. Although this cross-sectional shape is circular, it means a perfect circle. On the other hand, the present invention is not a perfect circle but an elliptical shape or a cross-sectional shape close to a circle that has an outermost diameter of a circle. There are things including.
１．７０００系アルミニウム合金組成：
本発明における７０００系アルミニウム合金組成は、人工時効処理後の機械部品、あるいは、この機械部品を模擬した素材押出材の、各組織について、小傾角粒界と大傾角粒界の平均割合と、平均方位差であるＫＡＭ値とを、規定する範囲に制御する前提となる。そして、同時に、人工時効処理後の機械部品あるいは押出材として、引張強さを８００ＭＰａ以上、全伸びを５％以上とするための前提となる。
1.7000 series aluminum alloy composition:
The 7000 series aluminum alloy composition in the present invention is a mechanical part after artificial aging treatment or an average ratio of a low-angle grain boundary and a large-angle grain boundary for each structure of a material extruded material simulating this machine part, and an average This is a precondition for controlling the KAM value, which is an 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.
このための７０００系アルミニウム合金組成は、質量％で、Ｚｎ：８．０〜１４．０％、Ｍｇ：２．０〜４．０％、Ｃｕ：０．５〜２．０％、Ｍｎ：０．２〜１．５％、Ｚｒ：０．０５〜０．３％を各々含有し、残部がＡｌ及び不可避的不純物からなる組成とする。この組成に、更に、質量％で、Ｃｒ：０．０５〜０．３％、Ｓｃ：０．０５〜０．３％のうちの一種または二種を選択的に含有してもよい。
また、以上の組成に、更に、質量％で、Ａｇ：０．０１〜０．２％、Ｓｎ：０．０１〜０．２％のうちの一種または二種を選択的に含有してもよい。
ここで、各元素の含有量の％表示は、以下に記載の各元素の含有量を含めて、全て質量％の意味である。
The 7000 series aluminum alloy composition for this purpose is, 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: 0.05 to 0.3%, respectively, with the balance being Al and inevitable impurities. The composition may further contain one or two of Cr: 0.05 to 0.3% and Sc: 0.05 to 0.3% selectively 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：８．０〜１４．０％
必須の合金元素であるＺｎは、Ｍｇとともに、後述する人工時効処理時に、ＭｇとＺｎとの金属間化合物である時効析出物を形成して強度を向上させる。Ｚｎ含有量が８．０％未満では機械部品としての強度が不足し、１４．０％を超えると、素材押出材用の鋳造ビレットの鋳造時に鋳塊割れが発生しやすくなり造塊が困難となる。
従って、Ｚｎ含有量は８．０〜１４．０％の範囲、好ましくは８．０〜１３．０％の範囲とする。なお、Ｚｎ含有量が高いと、ＳＣＣ感受性が鋭くなるが、それを抑えるためには、後述するＣｕあるいはＡｇを添加することが望ましい。
(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：２．０〜４．０％
必須の合金元素であるＭｇは、Ｚｎとともに、後述する人工時効処理時に、本発明で規定するＭｇとＺｎとの金属間化合物である時効析出物を形成して機械部品としての強度と伸びを向上させる。Ｍｇ含有量が２．０％未満では強度が不足し、４．０％を超えると、素材押出材用の鋳造ビレットの未再結晶温度域（再結晶温度未満の温度域）の低温での押出性が低下し、ＳＣＣ感受性も強くなる。従って、Ｍｇ含有量は２．０〜４．０％の範囲、好ましくは２．５〜３．５％の範囲とする。
(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 present invention during the artificial aging treatment described later, thereby improving the strength and elongation as a mechanical part. Let 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：０．５〜２．０％
Ｃｕは機械部品としての耐ＳＣＣ性を向上させる作用がある。Ｃｕ含有量が０．５％未満では、耐ＳＣＣ性向上効果が小さい。一方、Ｃｕ含有量が２．０％を超えると、素材押出材用の鋳造ビレットの鋳造時の割れが、鋳造ビレットの再結晶温度未満の低温での押出性を却って低下させる。従って、Ｃｕ含有量は０．５〜２．０％の範囲、好ましくは０．７〜１．８％の範囲とする。
(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：０．２〜１．５％
Ｍｎは、結晶粒を微細化するほか、分散粒子を形成して、機械部品の強度向上に寄与する。Ｍｎ含有量が０．２％未満では、含有量が不足して強度が低下する。一方、Ｍｎ含有量が１．５％を超えると、粗大晶出物を形成するため伸びが低下する。従って、従って、Ｍｎ含有量は０．２〜１．５％の範囲、好ましくは０．３〜１．２％の範囲とする。
(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：０．０５〜０．３％
Ｚｒは、微細な析出物を形成し、再結晶も抑制して、機械部品の強度向上に寄与する。Ｚｒの含有量が下限未満では、含有量が不足して強度が低下する。一方、Ｚｒの含有量が上限を超えた場合には、粗大晶出物を形成するため、伸びが低下する。従って、Ｚｒは０．０５〜０．３％の範囲、好ましくはＺｒ：０．１〜０．２５％の範囲とする。
(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 in the range of Zr: 0.1 to 0.25%.
本発明の実施形態に係る機械部品および押出材は、上述した組成に限定されるものではない。本発明の実施形態に係る機械部品および押出材の特性を維持できる限り、必要に応じてその他の元素を更に含んでよい。そのように選択的に含有させることができるその他の元素を以下に例示する。 The machine part 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）Ｃｒ：０．０５〜０．３％、Ｓｃ：０．０２〜０．５％のうちの一種または二種
ＣｒおよびＳｃは、Ｚｒと同様、微細な析出物を形成し、再結晶も抑制して機械部品の強度向上に寄与する。これらをいずれか一種、或いは二種を選択的に含有させる場合、ＣｒおよびＳｃの含有量がいずれも下限未満では、強度向上効果が低下することがある。一方、ＣｒおよびＳｃの含有量がそれぞれの上限を超えた場合には、粗大晶出物を形成するため、伸びが低下することがある。従って、Ｃｒは０．０５〜０．３％、Ｓｃは０．０２〜０．５％の各範囲であることが好ましく、より好ましくはＣｒは０．１〜０．２５％、Ｓｃは０．０５〜０．４％の各範囲とする。
(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, Cr is 0.1 to 0.25%, and Sc is 0.00. Each range is from 05 to 0.4%.
（７）Ａｇ：０．０１〜０．６％、Ｓｎ：０．０１〜０．２％のうちの一種または二種
ＡｇおよびＳｎは、人工時効処理での結晶粒界近傍の無析出帯の形成を抑制して機械部品の強度向上に寄与する。選択的に含有させる場合、ＡｇおよびＳｎの含有量が各々０．０１％未満では微細化効果が小さいことがある。一方、ＡｇおよびＳｎの含有量がそれぞれ、０．６％、０．２％を超えると、素材押出材用の鋳造ビレットの鋳造時に粗大な初晶化合物を形成し、押出加工時の焼付や、製品としての機械部品の伸びの低下をもたらすことがある。従って、Ａｇ含有量は０．６％以下が好ましく、０．５％以下がより好ましく、０．２％以下がさらに好ましい。Ｓｎ含有量は０．２％以下が好ましく、０．１５％以下がより好ましい。
(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、Ｂは、不可避的不純物であるが、アルミニウム合金鋳塊の結晶粒を微細化する効果があるので、７０００系合金としてＪＩＳ規格で規定する範囲での各々の含有を許容する。
(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）その他の元素：
これら記載した以外の、Ｆｅ、Ｓｉなどのその他の元素は不可避的な不純物である。溶解原料として、純アルミニウム地金以外に、アルミニウム合金スクラップの使用による、これら不純物元素の混入なども想定（許容）して、７０００系合金のＪＩＳ規格で規定する範囲での各々の含有を許容する。例えば、Ｆｅ、Ｓｉは各０．５質量％以下（０％を含む）の範囲で、それぞれ含有してもよい。
(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．組織：
本発明の機械的部品は、押出材を素材とするため、その組織は、必然的に７０００系アルミニウム合金の押出微細組織となっており、微細なナノレベルのサイズの析出物が、結晶粒内に多数存在して、高強度を達成している。
この析出物とは、結晶粒内に生成する、前記ＭｇとＺｎとの金属間化合物（組成はＭｇＺｎ２など）であり、これに他の合金組成に応じて更にＣｕ、Ｚｒなどの含有元素が含まれる微細分散相である。
2. Organization:
Since the mechanical part 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 formed in the crystal grains. In many cases, high strength is achieved.
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.
本発明では、更なる高強度化と伸び確保のために、機械部品の人工時効処理後の前記押出微細組織として、ＳＥＭ−ＥＢＳＤ法により測定された、小傾角粒界と大傾角粒界の平均割合と、平均方位差であるＫＡＭ値とを、更に制御する。また、機械部品用押出材（素材）の、この機械部品を模擬した、特定の抽伸加工、溶体化処理、人工時効処理を施した際の、ＳＥＭ−ＥＢＳＤ法により測定された結晶粒組織（結晶粒）の、小傾角粒界と大傾角粒界の平均割合と、平均方位差であるＫＡＭ値を制御する。 In the present invention, in order to further increase the strength and ensure the elongation, the average of the small-angle grain boundary and the large-angle grain boundary measured by the SEM-EBSD method as the extruded microstructure after the artificial aging treatment of the machine part. The ratio and the KAM value that is the average azimuth difference are further controlled. Moreover, the crystal grain structure (crystal) measured by the SEM-EBSD method when a specific drawing process, solution treatment, and artificial aging process of the extruded material (material) for machine parts were performed, simulating this machine part. Grain) and the KAM value which is the average misorientation.
すなわち、素材７０００系アルミニウム合金押出材を冷間加工して製造された機械部品の、前記人工時効処理後の組織を、あるいは、この機械部品を模擬した押出材（素材）の、機械部品の表面と軸中心との中間位置における前記押出加工方向に平行な面をＳＥＭ−ＥＢＳＤ法により測定した前記組織として規定する。
具体的には、傾角５〜１５°の小傾角粒界の平均割合を５％以上、傾角１５°を超える大傾角粒界の平均割合を２０％以上とするとともに、ＫＡＭ値の平均値を０．３°以上とする。
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 axis and the axis center is defined as the structure measured by the SEM-EBSD method.
Specifically, the average ratio of the low-angle grain boundaries with an inclination angle of 5 to 15 ° is 5% or more, the average ratio of the large-angle grain boundaries with an inclination angle of 15 ° is 20% or more, and the average KAM value is 0. .3 ° or more.
この機械部品の前記人工時効処理後の組織および機械的な特性は、素材押出材を実際に機械部品に転造または鍛造加工して人工時効処理せずとも、素材７０００系アルミニウム合金押出材に、機械部品を模擬した、抽伸加工と溶体化処理、人工時効処理を加えた後の組織および機械的な特性を調べれば、評価できる。
この機械部品を模擬するための好ましい処理条件としては、断面が円形な直径２０〜５０ｍｍの素材線棒押出材を減面率が８０〜９０％で抽伸加工まで行った線棒材に、４５０〜５００℃の温度で０．５〜１０時間保持する溶体化処理後、５０℃までの平均冷却速度を５０℃/秒以上として焼入れ処理を行い、その後１００〜２００℃で２〜１２０時間保持する人工時効処理を施した際の組織および機械的な特性を調べれば、実際の前記機械部品との相関性が高く、また再現性よく評価できる。
ただ、この再現性をより厳密なものとするためには、請求項６に規定した通り、機械部品を模擬する具体的な処理条件を、押出材を断面が円形な直径２５ｍｍの線棒押出材とした上で、減面率が８４％で抽伸加工して１０ｍｍφの断面が円形な線棒材とし、この線棒材を４８０℃の温度で５時間保持する溶体化処理後に、５０℃までの平均冷却速度を２００℃/秒として焼入れ処理を行い、その後１２０℃で７２時間保持する人工時効処理を施す、ワンポイントの条件とすることがより好ましい。
なお、前記抽伸の減面率とは、元の押出材の断面積をＡとし、抽伸した後の線棒材の断面積をａとすると、減少した面積(Ａ−a)を元の面積Ａで割って、％とした、（Ａ−a）×１００／Ａ（％）である。
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 preferable processing conditions for simulating this mechanical part, a wire rod material having a circular cross section of 20 to 50 mm in diameter and subjected to a drawing process with a reduction in area of 80 to 90% is applied to 450 to After solution treatment that is held at a temperature of 500 ° C. for 0.5 to 10 hours, an quenching treatment is performed with an average cooling rate up to 50 ° C. being 50 ° C./second or more, and then an artificial heat 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 rate is defined as follows: A is the cross-sectional area of the original extruded material and A is the cross-sectional area of the wire rod after drawing, and the reduced area (A-a) is the original area A. (A−a) × 100 / A (%).
このように、小傾角粒界が一定割合以上存在するとともに、一定割合の大傾角粒界と混在する、小傾角粒界と大傾角粒界の平均割合と、平均方位差であるＫＡＭ値を特定の範囲とする、微細加工組織にすることによって、機械部品の材料の変形過程で、局所的に歪が集中せずに、均一に変形する材料にできる。 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.
これによって、機械部品の局所的な破断を防止でき、引張強さが８００ＭＰａ以上であるような高強度とし、５％以上の伸びを確保できる。すなわち、前記人工時効処理後の機械部品の特性として、あるいはこの機械部品を模擬したアルミニウム合金押出材の前記人工時効処理後の特性として、引張強さが８００ＭＰａ以上、全伸びが５％以上とできる。
このような本発明の組織制御では、機械部品の耐ＳＣＣ性および耐粒界腐食感受性などの耐食性も低下させる恐れが無く、高強度化できる。
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. .
With such structure control of the present invention, there is no risk of reducing the corrosion resistance such as SCC resistance and intergranular corrosion resistance of mechanical parts, and the strength can be increased.
これらの要件を欠いて、前記人工時効処理後の組織として、機械部品あるいは機械部品用途を模擬した押出材の、傾角５〜１５°の小傾角粒界の平均割合が５％未満では、例えＫＡＭ値を満足しても、引張強さが８００ＭＰａ以上の特性が得られない。また、大傾角粒界の平均割合が２０％未満では、例えＫＡＭ値を満足しても、伸びが低下する。 Lacking these requirements, as the structure after the artificial aging treatment, if the average proportion of the small-angle grain boundaries with an inclination of 5 to 15 ° of the machine part or the extruded material simulating the use of the machine part is less than 5%, 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.
また、前記人工時効処理後の組織として、機械部品あるいは機械部品用途を模擬した押出材の、ＫＡＭ値の平均値が０．３°未満でも高強度化が難しくなる。
このＫＡＭ値自体の固有の作用効果は不明であるが、ＫＡＭ値の平均値を０．３°以上とすることで、機械部品の転位の運動を妨げる効果が著しく増して、強度と延性のバランスが向上するのではないかと推考される。
したがって、前記ＫＡＭ値の平均値が０．３°未満では、例え、前記小傾角粒界と大傾角粒界との両者の平均割合を満足しても、やはり引張強さが８００ＭＰａ以上、全伸びが５％以上の特性が得られない。
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.
（小傾角粒界と大傾角粒界の定義）
本発明で言う小傾角粒界とは、後述するＳＥＭ−ＥＢＳＤ法により測定した結晶方位の内、結晶方位の相違（傾角）が５〜１５°と小さい結晶粒の間の粒界である。また、本発明で言う大傾角粒界とは、この結晶方位の相違（傾角）が１５°を超え、１８０°以下の結晶粒の間の粒界である。
ここで、方位差が５°未満の結晶粒界の割合は、測定に供する試料の調製条件（表面状態）の影響が大きく、却って外乱となるため、本発明においては考慮せず、規定しない。したがって、この方位差が５°未満の結晶粒界と、前記小傾角粒界および大傾角粒界を合わせて、割合が１００％となる。
この小傾角粒界の平均割合として、本発明では、測定した小傾角粒界の結晶粒界の全長（測定された全小傾角粒の結晶粒界の合計の長さ）の、同じく測定した、結晶方位の相違（方位差）が２〜１８０°の結晶粒界の全長（測定された全結晶粒の結晶粒界の合計の長さ）に対する割合を、傾角５〜１５°の小傾角粒界の割合と規定している。すなわち、規定する傾角５〜１５°の小傾角粒界の割合（％）は、〔（５〜１５°の結晶粒界の全長）／（２〜１８０°の結晶粒界の全長）〕×１００として計算でき、この値の平均を５％以上とする。なお、製造の限界から、５〜１５°の小傾角粒界の割合の上限は５０％程度である。
(Definition of low-angle and high-angle grain boundaries)
The low-angle grain boundary referred to in 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. The large tilt grain boundary referred to in the present invention is a grain boundary between crystal grains having a difference in crystal orientation (tilt angle) of more than 15 ° and 180 ° or less.
Here, the proportion of crystal grain boundaries with an orientation difference of less than 5 ° is largely influenced by the preparation conditions (surface state) of the sample to be measured and is disturbed. 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%.
As an average ratio of the low-angle grain boundaries, in the present invention, the total length of the grain boundaries of the measured small-angle grain boundaries (the total length of the grain boundaries of all the small-angle grains measured) was also measured. The ratio of the difference in crystal orientation (orientation difference) with respect to the total length of the grain boundaries (measured total length of all the grain boundaries) of 2 to 180 ° is a small tilt grain boundary with an inclination of 5 to 15 °. The ratio is specified. That is, the ratio (%) of the low-angle grain boundary with the specified inclination angle of 5 to 15 ° is [(the total length of the crystal grain boundary of 5 to 15 °) / (the total length of the 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 proportion of the small tilt grain boundaries of 5 to 15 ° is about 50%.
一方、大傾角粒界の平均割合は、同じく、測定した大傾角粒界の結晶粒界の全長（測定された全小傾角粒の結晶粒界の合計の長さ）の、同じく測定した、結晶方位の相違が２〜１８０°の結晶粒界の全長（測定された全結晶粒の結晶粒界の合計の長さ）に対する割合を、傾角１５°を超える大傾角粒界の割合と規定する。すなわち、規定する大傾角粒界の割合（％）は、〔（１５°を超え１８０°以下の結晶粒界の全長）／（２〜１８０°の結晶粒界の全長）〕×１００として計算でき、この値の平均を２０％以上とする。大傾角粒界の割合は９０％超まで増加させることは可能であり、本願では傾角５〜１５°の小傾角粒界の割合を５％以上とするため、実質的に大傾角粒界の割合の上限は９５％である。 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 crystal grain boundary 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 boundary 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 greater 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 the large tilt grain boundaries can be increased to more than 90%. In this application, the ratio of the small tilt grain boundaries with the tilt angle of 5 to 15 ° is set to 5% or more. The upper limit is 95%.
（ＫＡＭ値の定義）
ＫＡＭ値とは、Ｋｅｒｎｅｌ Ａｖｅｒａｇｅ Ｍｉｓｏｒｉｅｎｔａｔｉｏｎ値の略であり、ＳＥＭ−ＥＢＳＤ法により測定された結晶粒組織（結晶粒）の平均方位差である。
このＫＡＭ値自体は、残存ひずみと相関があることが、例えば、「材料」（Journal of the Society of Materials Science, Japan）Vol.58、No.7, P568-574,July 2009などで公知である。また、ＫＡＭ値は、隣接する測定点間の結晶方位の差である局所方位差を、平均方位差として定量化した値であることも公知である。
更に、このＫＡＭ値は、アルミニウム合金以外の、銅合金板や鋼板の分野で、プレス成形性および曲げ加工性向上のために制御することが公知である。ただ、この平均ＫＡＭ値と、アミニウム合金特性との関係は、これまでは知られておらず、前記銅合金板や鋼板の分野でのＫＡＭ値制御の目的であるプレス成形性および曲げ加工性と、本発明が課題とする高強度化および高延性化とでは、その機構が大きく異なる。
(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．組織の測定：
以上の組織の測定は、機械部品や押出材の表面と、その軸中心との中間位置における、前記押出加工方向に平行な面（断面）を観察面として、ＳＥＭ−ＥＢＳＤ法により測定して行う。
前記押出加工方向に平行な面（断面）を観察面とするのは、押出加工組織である結晶粒の長手方向（押出方向）の結晶方位を、ＳＥＭ−ＥＢＳＤ法により測定するためである。
これによって、機械部品や、アルミニウム合金押出材の、人工時効処理後の組織として、小傾角粒界と大傾角粒界の平均割合と、平均方位差であるＫＡＭ値を測定できる。
3. Tissue measurement:
The measurement of the above structure is performed by measuring by the 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 axial 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.
測定箇所は、測定範囲（面積）が、押出方向と平行方向に６００μｍ、直角方向に４００μｍの範囲となるように、試料を機械部品や押出材の前記した断面から採取する。測定は任意の５箇所から採取した試料５個について行い、これを平均化する。 Samples are taken from the above-described cross sections of mechanical parts and extruded materials 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.
ＳＥＭ−ＥＢＳＤ（ＥＢＳＰ）法は、電界放出型走査電子顕微鏡（Field Emission Scanning Electron Microscope: FESEM）に、後方散乱電子回折像（Electron Back Scattering (Scattered) Diffraction Pattern: EBSD）システムを搭載した結晶方位解析法である。
より具体的に、ＳＥＭ−ＥＢＳＤの前記観察用試料の調整は、前記観察試料(断面組織)を、更に機械研磨後電解エッチングして鏡面化する。そして、ＦＥＳＥＭの鏡筒内にセットし、試料の鏡面化した表面に、電子線を照射してスクリーン上にＥＢＳＰを投影する。これを高感度カメラで撮影して、コンピュータに画像として取り込む。コンピュータでは、この画像を解析して、既知の結晶系を用いたシミュレーションによるパターンとの比較によって、結晶の方位が決定される。算出された結晶の方位は３次元オイラー角として、位置座標（ｘ、ｙ、z）などとともに記録される。このプロセスが全測定点に対して自動的に行なわれるので、測定終了時には、観察面における数万〜数十万点の結晶方位データが得られる。
The SEM-EBSD (EBSP) method uses a field emission scanning electron microscope (FESEM) and a back-scattered electron diffraction image (Electron Back Scattering (Scattered) Diffraction Pattern: EBSD) system. Is the law.
More specifically, the observation sample of SEM-EBSD is adjusted 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, crystal orientation data of tens of thousands to hundreds of thousands of points on the observation surface can be obtained at the end of measurement.
これらの結晶解析では、電子チャネリングパターン法（ＥＣＰ法）による結晶解析手法を用い、ＳＥＭと組み合わせて、材料に電子線を照射して走査しながら、材料表面で生じる電子線後方散乱回折により菊池線回折図形すなわちＥＢＳＤパターンを測定、解析する。これらＦＥＳＥＭにＥＢＳＤシステムを搭載した結晶方位解析法の詳細は、神戸製鋼技報/Vol.52 No.2(Sep.2002)P66-70などに詳細に記載されている。 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 and the like.
これによって、機械部品あるいは押出材の組織を測定、解析することで、これらの各部位の微小領域における、結晶粒径、半径方向の結晶粒の切片長さ、および結晶方位に関する情報が得られる。すなわち、前記小傾角粒界と大傾角粒界の平均割合、および前記平均方位差であるＫＡＭ値が測定、解析できる。 Thus, by measuring and analyzing the structure of the machine part or the extruded material, information on the crystal grain size, the length of the crystal grain in the radial direction, and the crystal orientation in the micro region of each part can be obtained. 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．ＫＡＭ値の測定：
なお、ＫＡＭ値の測定に際しては、前記ＳＥＭ−ＥＢＳＤ法による測定の再現性のために、ＫＡＭ値を計算する基準のピクセルと隣接するピクセルの間の位置関係として、第ｎ近接までの領域内の全てのピクセルを計算するかを設定する必要があり、その設定は、本発明では第１近接までとした。
解析ソフトでの設定は、隣接（Ｎｅａｒｅｓｔ Ｎｅｉｇｈｂｏｒ）の設定を１ｓｔとした。また、本発明では、各基準のピクセル毎に得られたＫＡＭ値に対して、最大方位差の上限を５°として、５°以内のＫＡＭ値となるピクセルのデータのみを用いて、解析範囲内の平均ＫＡＭ値を算出した。解析ソフトでの設定は、最大方位差（Ｍａｘｉｍｕｍ ｍｉｓｏｒｉｅｎｔａｔｉｏｎ）を５°と設定した。
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 present invention.
As for the setting in the analysis software, the setting of the neighbor (Nearest Neighbor) is set to 1st. Further, in 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 data of the pixel having the KAM value within 5 ° is used. The average KAM value was calculated. In the setting with the analysis software, the maximum misorientation was set to 5 °.
５．製造方法：
本発明の押出材および機械部品の好ましい製造方法について説明する。
5. Production method:
A preferred method for producing the extruded material and machine part of the present invention will be described.
５−１．押出材の製造方法
先ず、押出材（押出形材）の好ましい製造方法について説明する。以下に説明するように、本発明の実施形態に係る押出材は、適切な条件で溶解・鋳造および均質化熱処理条件を行った後、未済結晶域の低い押出温度で、静水圧押出を行うことにより得ることができる。本発明の実施形態に係る押出材のように、８質量％以上の高い含有量のＺｎを有する７０００系Ａｌ合金では、直接押出または間接押出等の通常の押出方法では、押出素材であるビレットとダイスとの間の摩擦によって焼付きが生じるため、再結晶温度域未満の温度で押出加工を行うことができず、微細な加工組織を有する押出材を得ることができない。本発明の実施形態に係る製造方法では、静水圧押出により熱間押出を行うため、８質量％以上の高いＺｎ含有量であっても、再結晶温度域未満の温度で押出加工を行うことができ、微細な加工組織を有する押出材を得ることができる。そして、このような高いＺｎ含有量と、微細な加工組織とを有する押出材を用いて、後述する条件により機械部品の製造することで、高い引張り強度と全伸びとを有する機械部品を得ることができる。以下に、本発明の実施形態に係る押出材の製造方法について、工程順に説明する。
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）溶解、鋳造
先ず、溶解、鋳造工程では、上記７０００系成分組成範囲内に溶解調整されたアルミニウム合金溶湯を、半連続鋳造法（ＤＣ鋳造法）等の通常の溶解鋳造法を適宜選択して鋳造してビレットとする。
(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）均質化熱処理
熱間押出に先立って、鋳造されたアルミニウム合金ビレット（鋳塊）を均質化熱処理（均熱処理）して、組織の均質化（鋳塊組織中の結晶粒内の偏析をなくすなど）を行う。均熱温度を４００〜４５０℃に制御することで、Ｚｒ系化合物、およびＭｎ、Ｃｒ、Ｓｃからなる化合物を微細に分散させ、押出後および溶体化後の結晶粒組織を微細化する。４００℃未満では十分な微細化効果が得られない。４５０℃を超えると、これらの化合物が粗大化するため、微細化効果が低下する。また、均熱時の保持時間の目安は１〜８時間程度とする。
(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 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. Moreover, the standard of the holding time at the time of soaking shall be about 1 to 8 hours.
（３）熱間押出
熱間押出によって、最終の機械部品形状に応じた、この最終形状に近い押出材形状とする。
この際、押出材の表層部だけでなく、押出材内部の再結晶化も抑制して、微細加工組織とするためには、再結晶温度未満の未再結晶域の３００〜４００℃の範囲の低い押出温度（ビレットの押出開始温度と押出加工中の温度）で押出を行うことが好ましい。押出温度を、３００〜４００℃の範囲とすることで、押出材の表層部だけでなく、内部の再結晶化も抑制して、微細な押出加工組織とすることができる。
(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 obtain a finely textured 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 internal recrystallization can be suppressed and a fine extruded structure can be obtained.
この押出温度が４００℃を超えると、押出時の温度が上昇し、高温で再結晶が起こりやすくなり、押出材の表層部および内部に粗大な再結晶組織が形成され、耐食性の劣化および強度の低下をもたらす。一方で、押出温度は低いほど良いが、低温側では変形抵抗が増大して押出が困難になるため、３００℃程度を下限とする。好ましくは３２０〜３８０℃とする。 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. Preferably it is set as 320-380 degreeC.
また、押出速度としては、押出時の加工発熱を押さえ、押出時の前記再結晶を抑制するために１０ｍ／分以下とすることが好ましい。より好ましくは７ｍ／分以下とする。
これら熱間押出後の冷却については、放冷を含めてその手段および冷却速度を問わないが、押出工程の効率からは、強制的に空冷することが好ましい。
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.
（押出方法）
押出方法としては、前記した未再結晶域の好ましい押出条件にて、静水圧押出で行う。
押出方法を直接押出または間接押出とする場合、静水圧押出に比べれば効率的ではあるが、押出材表層部（表面部）の再結晶粒層が、押出材内部の比較的細かい、押出方向に伸長した繊維状結晶粒（押出加工）組織に比して、粒状の粗大な結晶粒になりやすい問題がある。また、本発明のように、Ｚｎ含有量が８％を超えるような７０００系アルミニウム合金を押出する場合には、直接押出あるいは間接押出の場合には、再結晶温度域未満の押出加工はかなり困難がある。
これは、たとえ、押出素材であるビレットを再結晶温度域未満の低い加熱温度としても、直接押出あるいは間接押出では、その押出機の構造上、ビレットがコンテナ壁面およびダイスと接触して押し出されるために摩擦熱が生じ、この結果、押出中の温度は必然的に再結晶温度域となる。このため、必然的に、特許文献１自身で問題とするような粗大な再結晶（粒）層が押出材の表層部にできやすい。
(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. In addition, when extruding a 7000 series aluminum alloy having a Zn content exceeding 8% as in the present invention, in the case of direct extrusion or indirect extrusion, extrusion processing below the recrystallization temperature range is considerably difficult. There is.
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.
これに対して、熱間静水圧押出は、コンテナとビレットの間に潤滑剤を入れ、この潤滑剤の中に、押出用のビレットが浮いている状態を作り、ステム（ダミーブロック付き）によって押し出す。このため、ビレットは、この潤滑剤の作用によって、直接押出および間接押出と違って、コンテナおよびダイスと直接接触しない。すなわち、ビレットが直接接触するのは、ダイスの厚みの約５ｍｍ程度を通過する間だけである。この結果、摩擦および摩擦熱も軽減され、メタルフローも均一に近くなる。この結果、Ｚｎ含有量が高い、本発明のような７０００系アルミニウム合金のビレットであっても、再結晶温度未満の低温でも押出加工が可能であり、押出材の表層部および内部の再結晶粒層を抑制（微細化）することが可能となる。
このため、熱間静水圧押出による押出材は、再結晶粒層を含めて、あるいは再結晶粒層が存在していても、表層部から内部までの組織の均一性が図れる。この結果、線棒あるいは線棒製品の素材としても、抽伸性および伸線性あるいは加工性、成形性が著しく向上する。また、本発明のように再結晶粒層を抑制すれば、微細な押出加工組織であることによって、アルミニウム合金製ボルトなどの線棒製品に要求される耐へたり性などの基本特性も保証できる。
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 like the present invention having a high Zn content can be extruded even at a low temperature lower than the recrystallization temperature, and the recrystallized grains in the surface layer portion and inside of the extruded material The layer can be suppressed (miniaturized).
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 present invention, the basic characteristics such as sag resistance required for wire rod products such as aluminum alloy bolts can be ensured by the fine extruded structure. .
５−２．機械部品の製造方法
以上のようにして得られた熱間押出後の押出材は、更に前記各用途の機械部品の製品形状に冷間加工される。
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.
押出材のボルトなどの機械部品への一般的な加工工程は、押出材を焼鈍後細径化のために抽伸して洗浄し、更に焼鈍した上で転造または鍛造して機械部品の製品形状とする。そして、このような製品加工の完了後に、溶体化および焼入れ処理を行い、更に人工時効処理を行って強度を向上させる。 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.
ちなみに、前記焼鈍は選択的であり、抽伸または転造の途中で焼鈍処理を行ってもよい。また、前記抽伸または転造などの冷間加工は、当然ながら、ボルトおよびナット等のねじ部品、歯車（ギア）、軸（シャフト）、軸受け（ベアリング）、ばね（スプリング）などの、具体的な用途および形状に応じて、その条件も含めて変更される。 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）溶体化処理
本発明の実施形態に係る製造方法では、機械部品の溶体化処理は、４５０℃以上、５００℃以下の温度で、０．５〜１０時間保持する。保持温度が４５０℃未満、または保持時間が０．５時間未満では、Ｍｇ、Ｚｎの固溶が不十分になって強度が不足する。そして、大傾角粒界の平均割合が２０％未満となって伸びが低下する。
一方、保持温度が５００℃を上回ったり、保持時間が１０時間を超えると、小傾角粒界の平均割合が５％未満となり、さらにはＫＡＭ値の平均が小さくなり、強度が不足する。
(1) Solution Treatment In the manufacturing method according to the embodiment of the present invention, the solution treatment of the mechanical 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）焼入れ処理
本発明の実施形態に係る製造方法では、溶体化処理後の焼入れ処理として、溶体化処理温度から５０℃までの冷却（降温）速度は、平均で５０℃/秒以上とする。平均冷却速度が５０℃/秒未満と小さすぎては、粗大な再結晶が生じて、溶体化処理後の組織を、傾角５〜１５°の小傾角粒界の平均割合が５％未満となり、ＫＡＭ値の平均が小さくなり、強度が不足する。そして、強度および伸びを低下させる粗大な粒界析出物も形成され、強度および全伸びが不足する。平均冷却速度の上限は、設備能力の限界から、およそ５００℃/秒程度である。
前記５０℃から室温までの冷却速度は特に制限は無く、そのまま引き続き急冷しても、あるいは急冷を停止して放冷してもよい。
(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 small 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）人工時効処理
本発明の実施形態に係る製造方法では、機械部品の（あるいは機械部品を模擬した押出材の）人工時効処理の条件を、７０００系アルミニウム合金押出材の一般的な人工時効処理条件に比べて、比較的短時間の時効処理としても、高強度化を達成できる利点がある。
本発明の実施形態に係る製造方法では、１００〜２００℃での人工時効処理を２〜１２０時間行うこととする。
人工時効処理温度が２００℃を超えると、加工組織の回復が進むため、傾角５〜１５°の小傾角粒界の平均割合が５％未満となり、またＫＡＭ値の平均が小さくなり、強度が低下する。
一方、人工時効処理の時間が１２０時間を超えても、加工組織の回復が進むため、傾角５〜１５°の小傾角粒界の平均割合が５％未満となり、またＫＡＭ値の平均が小さくなり、強度が低下する。
(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 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 ° becomes less than 5%, the average of the KAM value decreases, and the strength decreases. To do.
On the other hand, even if the artificial aging time exceeds 120 hours, the recovery of the processed structure proceeds, so that 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.
以上に説明した本発明の実施形態に係る機械部品および押出材の特性、ならびにその製造方法に接した当業者であれば、試行錯誤により、上述した製造方法と異なる製造方法により本発明の実施形態に係る機械部品および押出材を得ることができる可能性がある。 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.
以下、実施例を挙げて本発明をより具体的に説明するが、本発明はもとより下記実施例によって制限を受けるものではなく、前・後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも可能であり、それらは何れも本発明の技術的範囲に含まれる。 EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.
次に、本発明の実施例を説明する。本発明は以下の実施例によって制限を受けるものではなく、前記、後記の趣旨に適合し得る範囲で変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に包含される。 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．サンプル作成
表１に示す組成の７０００系アルミニウム合金鋳塊を鋳造後、均熱処理を経て、熱間静水圧押出し、各例とも共通して、断面が円形な直径２５ｍｍの線棒押出材を製造した。
この線棒押出材の押出条件は、各例とも共通させて、前記鋳塊を４３０℃×５時間の均熱処理した後、３５０℃の未再結晶領域の押出開始温度で、および５ｍ／分の押出速度によって、熱間静水圧押出する条件にて行った。
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.
そして、各例とも共通して、機械部品用途を模擬して、前記線棒押出材に減面率が８４％の抽伸加工を施し、１０ｍｍφの断面が円形な線棒材とした上で、この線棒材に、表１に示す各条件で、溶体化および焼入れ処理を行い、更に人工時効処理を行った。 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.
更に、この人工時効処理後の機械部品を模擬した線棒材から、試験片を採取し、試験片組織の小傾角粒界と大傾角粒界の平均割合と、平均方位差であるＫＡＭ値を、ＳＥＭ−ＥＢＳＤ法により測定した。また、この人工時効処理後の材料の機械的な特性を、機械部品の特性を模擬して、測定した。これらの結果も表１に示す。
ちなみに、前記人工時効処理後の組織は、組成、溶体化および焼入れ処理条件、人工時効処理などの条件を種々変えてつくり分けた。
この際、溶体化処理とその後の焼入れ処理は、表１の通り、溶体化処理の保持温度と時間、各溶体化処理温度から５０℃までの平均冷却速度を種々変えて行った。
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.
前記人工時効処理後の線棒材から採取した前記試験片は、丸棒平滑引張試験片（３ｍｍφ×１２mmＧＬ）とし、この試験片の表面と軸中心との中間（真ん中）位置における、押出加工方向に平行な面（断面）を観察面とできるように採取した。 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．組織の測定：
前記試験片の組織として、小傾角粒界と大傾角粒界の平均割合と、平均方位差であるＫＡＭ値を、ＳＥＭ−ＥＢＳＤ法による測定を、前記した測定方法により行った。具体的には、前記ＴＳＬ社製ＥＢＳＰ測定・解析システム(OIM）を搭載した、日本電子社製ＳＥＭ（JEOL JSM 6500F）を用いた。
各例とも、前記丸棒平滑引張試験片５個について、押出材の表面と軸中心との中間（真ん中）位置における、押出加工方向に平行な面（断面）を観察面として測定し、前記試験片５個の各測定・解析結果を平均化した。
各試験片の測定領域は各々押出材の押出方向に６００μｍ×押出方向と直角方向（押出材幅方向）に４００μｍの領域（２４００００μｍ２）とし、測定ステップ間隔も共通して０．５μｍとした。
2. Tissue measurement:
As the structure of the test piece, the average ratio of the small-angle grain boundary and the large-angle grain boundary and the KAM value, which is the average orientation difference, were measured by the SEM-EBSD method according to the above-described measurement method. 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．機械的性質：
前記丸棒平滑引張試験片の機械的性質は、引張試験機を用いて、１２ｍｍ／分のクロスヘッド速度で、常温中で、破断まで引張試験を行った。応力―歪速度より、引張強さ（ＭＰａ）を測定した。全伸び（％）は前記引張試験時の引張試験前後のケガキ線の間隔（引張試験前の間隔１０ｍｍ）より算出した。なお、これらの測定値は、各例とも前記５個の試験片の平均値とした。
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．まとめ
表１の発明例１〜７は、表１の通りアルミニウム合金組成は本発明範囲内である。また、熱間静水圧押出を未再結晶領域にて行うなど、好ましい製造条件にて押出材が製造されている。更に、溶体化および焼入れ処理、人工時効処理も好ましい製造条件にて行なわれている。
この結果、前記発明例は、表１の通り、小傾角粒界と大傾角粒界の平均割合およびＫＡＭ値の平均が規定範囲内であり、引張強さが８００ＭＰａ以上の高強度で、全伸びが５％以上である高い延性の特性を有する。
4). Summary As shown in Table 1, Invention Examples 1 to 7 in Table 1 have the 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.
これに対して、表１の比較例１〜５は、表１の通りアルミニウム合金組成が本発明範囲から外れている。このため、これら比較例は、押出材および模擬した機械部品が好ましい製造方法で製造されているものの、表１の通り、小傾角粒界と大傾角粒界の平均割合および／またはＫＡＭ値の平均が規定範囲から外れ、あるいはこれら組織が規定範囲内であっても、引張強さが８００ＭＰａ未満と低いか、或いは全伸びが低い。
比較例１はＺｎが下限から外れ、強度が不足した。
比較例２はＭｇが下限から外れ、強度が不足した。
比較例３はＭｎが下限から外れ、強度が不足した。
比較例４はＭｎが上限から外れ、延性が不足した。
比較例５はＺｒが下限から外れ、傾角５〜１５°の小傾角粒界の平均割合およびＫＡＭ値の平均が小さくなり、強度が不足した。
On the other hand, in Comparative Examples 1 to 5 in Table 1, the aluminum alloy composition is out of 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, and the average ratio of the small-angle grain boundaries having an inclination of 5 to 15 ° and the average of the KAM values were small, and the strength was insufficient.
また、表１の比較例６〜１１は、表１の通りアルミニウム合金組成は本発明範囲内であるものの、表１の通り、機械部品を模擬した製造条件が好ましい範囲から外れて製造されている。この結果、このため、これら比較例は、表１の通り、小傾角粒界と大傾角粒界の平均割合および／またはＫＡＭ値の平均が、押しなべて規定範囲から外れ、引張強さが８００ＭＰａ未満と低く、全伸びさえも低くなることもある。
比較例６は、前記機械部品を模擬した溶体化処理温度が低すぎ、ＺｎとＭｇの固溶量が減少し、傾角１５°を超える大傾角粒界の平均割合も小さくなり、強度および延性が不足した。
比較例７は、前記機械部品を模擬した溶体化処理温度が高すぎ、傾角５〜１５°の小傾角粒界の平均割合およびＫＡＭ値の平均が小さくなり、強度が不足した。
比較例８は、前記機械部品を模擬した溶体化処理の保持時間が長すぎ、傾角５〜１５°の小傾角粒界の平均割合およびＫＡＭ値の平均が小さくなり、強度が不足した。
比較例９は、前記機械部品を模擬した溶体化処理後の冷却速度が遅すぎ、傾角５〜１５°の小傾角粒界の平均割合およびＫＡＭ値の平均が小さくなり、強度および延性が不足した。
比較例１０は、前記機械部品を模擬した人工時効処理の温度が高すぎ、傾角５〜１５°の小傾角粒界の平均割合およびＫＡＭ値の平均が小さくなり、強度が不足した。
比較例１１は、前記機械部品を模擬した人工時効処理の保持時間が長すぎ、傾角５〜１５°の小傾角粒界の平均割合およびＫＡＭ値の平均が小さくなり、強度が不足した。
Moreover, although Comparative Examples 6-11 of Table 1 have the aluminum alloy composition in the range of the present invention as shown in Table 1, as shown in Table 1, the manufacturing conditions simulating machine parts are manufactured out of the preferred range. . 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 small-angle grain boundaries with an inclination of 5 to 15 ° and the average of 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 small-angle grain boundaries having an inclination angle 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 part 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 reduced, and the strength and ductility were insufficient. .
In Comparative Example 10, the temperature of the artificial aging treatment simulating the mechanical part was too high, 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 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 with an inclination of 5 to 15 ° and the average of the KAM values were small, and the strength was insufficient.
本発明によれば、人工時効処理後の引張強さが８００ＭＰａ以上、全伸びが５％以上である高強度特性が得られる、７０００系アルミニウム合金押出材からなる前記機械部品およびその製造方法、その素材である７０００系アルミニウム合金押出材を提供できる。このため、本発明は、軽量化された前記機械部品として、好適に用いることができる。 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.
Claims (10)
Ｚｎ：８．０〜１４．０％、
Ｍｇ：２．０〜４．０％、
Ｃｕ：０．５〜２．０％、
Ｍｎ：０．２〜１．５％、
Ｚｒ：０．０５〜０．３％を各々含有し、
残部がＡｌ及び不可避的不純物からなる７０００系アルミニウム合金の押出加工組織を有する機械部品であって、
この機械部品の表面と軸中心との中間位置における前記押出加工方向に平行な面をＳＥＭ−ＥＢＳＤ法により測定した前記組織および特性として、
傾角５〜１５°の小傾角粒界の平均割合が５％以上であり、
傾角１５°を超える大傾角粒界の平均割合が２０％以上であり、
ＫＡＭ値の平均値が０．３°以上であり、
引張強さが８００ＭＰａ以上、
全伸びが５％以上であることを特徴とする機械部品。 % 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 on 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.
Ｚｎ：８．０〜１４．０％、
Ｍｇ：２．０〜４．０％、
Ｃｕ：０．５〜２．０％、
Ｍｎ：０．２〜１．５％、
Ｚｒ：０．０５〜０．３％を各々含有し、
残部がＡｌ及び不可避的不純物からなる７０００系アルミニウム合金の機械部品用押出材であって、
この押出材を、機械部品を模擬して、断面が円形な直径２５ｍｍの線棒押出材とした上で、減面率が８４％で抽伸加工して１０ｍｍφの断面が円形な線棒材とし、この線棒材を４８０℃の温度で５時間保持する溶体化処理後に、５０℃までの平均冷却速度を２００℃/秒として焼入れ処理を行い、その後１２０℃で７２時間保持する人工時効処理を施した際の、この線棒材の表面と軸中心との中間位置における前記押出加工方向に平行な面をＳＥＭ−ＥＢＳＤ法により測定した組織および特性として、傾角５〜１５°の小傾角粒界の平均割合が５％以上、かつ傾角１５°を超える大傾角粒界の平均割合が２０％以上であるとともに、ＫＡＭ値の平均値が０．３°以上であり、引張強さが８００ＭＰａ以上、全伸びが５％以上であることを特徴とする押出材。 % 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 extrusion direction at the intermediate position between the surface of the wire rod and the center of the shaft 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.
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| WO2018088351A1 (en) * | 2016-11-14 | 2018-05-17 | 株式会社神戸製鋼所 | Aluminum alloy extruded material |
| WO2019124554A1 (en) * | 2017-12-22 | 2019-06-27 | 日本発條株式会社 | Aluminum alloy, spring made of aluminum alloy, and fastening member made of aluminum alloy |
| CN112176226A (en) * | 2019-07-04 | 2021-01-05 | 日立金属株式会社 | Aluminum alloy wire and method for producing same |
| WO2024143788A1 (en) * | 2022-12-29 | 2024-07-04 | 한국재료연구원 | Ultra-high strength aluminum alloy sheet material and manufacturing method therefor |
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| WO2018088351A1 (en) * | 2016-11-14 | 2018-05-17 | 株式会社神戸製鋼所 | Aluminum alloy extruded material |
| WO2019124554A1 (en) * | 2017-12-22 | 2019-06-27 | 日本発條株式会社 | Aluminum alloy, spring made of aluminum alloy, and fastening member made of aluminum alloy |
| JP6602508B1 (en) * | 2017-12-22 | 2019-11-06 | 日本発條株式会社 | Aluminum alloy, aluminum alloy spring and aluminum alloy fastening member |
| US11505851B2 (en) | 2017-12-22 | 2022-11-22 | Nhk Spring Co., Ltd. | Aluminum alloy, aluminum alloy spring, and fastening member made of aluminum alloy |
| CN112176226A (en) * | 2019-07-04 | 2021-01-05 | 日立金属株式会社 | Aluminum alloy wire and method for producing same |
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