JP5671422B2 - Method for producing high strength 7000 series aluminum alloy member and high strength 7000 series aluminum alloy member - Google Patents
Method for producing high strength 7000 series aluminum alloy member and high strength 7000 series aluminum alloy member Download PDFInfo
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本発明は高強度７０００系アルミニウム合金部材の製造方法および高強度７０００系アルミニウム合金部材に関するものである。本発明で言うアルミニウム合金部材とは、素材としての押出形材や圧延板材を製品形状（使用形状）に残留応力の発生を伴う成形加工したものを言う。 The present invention relates to a method for producing a high strength 7000 series aluminum alloy member and a high strength 7000 series aluminum alloy member. The aluminum alloy member referred to in the present invention refers to a product obtained by forming a extruded shape or rolled plate as a raw material into a product shape (use shape) accompanied by generation of residual stress.
７０００系アルミニウム合金部材は、周知の通り、素材の押出形材の組成として、主成分であるＺｎ、ＭｇやＣｕなどの合金元素量を調整し、その時効硬化性を利用した人工時効処理（人工時効硬化処理）などの調質によって、必要な高強度を確保している。主な用途例としては、バンパリィンホース、ドアビームなどの自動車用補強部材あるいは航空機用などの構造部材があり、薄肉化による軽量化のためにも、より高強度化が求められ、０．２％耐力で３００ＭＰａ以上の高強度が要求される。 As is well known, the 7000 series aluminum alloy member is an artificial aging treatment (artificial aging treatment) using the age hardening property by adjusting the amount of alloying elements such as Zn, Mg and Cu as main components as the composition of the extruded shape of the material. The required high strength is ensured by tempering such as age hardening. Examples of main applications include automotive reinforcement members such as bumper hose and door beam, and structural members for aircraft, etc. In order to reduce the weight by thinning, higher strength is required, 0.2% A high strength of 300 MPa or more is required in terms of yield strength.
ただ、７０００系アルミニウム合金部材は前記合金元素量が多いために、他の合金系に比して、耐ＳＣＣ性（耐応力腐食割れ性）が低いことが知られている。 However, it is known that the 7000 series aluminum alloy member has a low SCC resistance (stress corrosion cracking resistance) as compared with other alloy series because of the large amount of the alloy elements.
また、７０００系アルミニウム合金部材は、周知の通り、その時効硬化性ゆえに、素材としての押出形材として製造されたあと、自然時効硬化（以下、自然時効あるいは室温時効とも言う）によって大きく硬化する。例えば、熱間押出直後は０．２％耐力で１５０ＭＰａ程度であった強度が、自然時効（室温時効）２０日経過後には、０．２％耐力で２４０ＭＰａ程度まで硬化してしまう。 As is well known, the 7000 series aluminum alloy member is hardened by natural age hardening (hereinafter also referred to as natural aging or room temperature aging) after being manufactured as an extruded shape as a raw material because of its age hardening. For example, the strength which was about 150 MPa with 0.2% proof stress immediately after hot extrusion is cured to about 240 MPa with 0.2% proof strength after 20 days of natural aging (room temperature aging).
このように自然時効した素材押出形材は、曲げ加工、断面の潰し加工、打抜き加工から選択される、塑性加工を伴う、部材への成形加工の際の成形性が極端に低下してしまう。これは、製造された素材押出形材に対して、別途に再加熱して溶体化処理（溶体化および焼入れ処理）を施した後でも同様で、このような調質を施した後に、成形されるまでの時間が経過するほど、自然時効が進展する。 In this way, the material extruded shape that has been naturally aged is extremely deteriorated in the formability during the forming process with respect to the member, which is selected from the bending process, the crushing process of the cross section, and the punching process. This is the same even after the manufactured material extruded profile is separately reheated and subjected to a solution treatment (solution treatment and quenching treatment). The natural aging progresses as time elapses.
また、前記成形加工が可能であっても、素材押出形材が製造されてから成形加工されるまでの時間の違い、すなわち自然時効硬化の程度（進行）の違いによって、押出形材同士の強度が異なる、すなわち押出形材同士の強度がばらつくという問題が生じる。また、押出形材同士によって、この耐力に依存した成形時のスプリングバック量がばらつく問題も生じ、押出形材ごとに部材への成形精度がばらつくという問題もある。更に、自然時効が進展した場合、押出形材の均一伸びや局部伸びが低下し、部材への成形性や成形精度が更に低下するという問題もある。 In addition, even if the molding process is possible, the strength of the extruded profiles depends on the difference in time from the production of the extruded material to the molding process, that is, the degree of natural age hardening (progress). Are different, that is, the strength of the extruded profiles varies. In addition, there is a problem that the amount of springback during molding depending on the proof stress varies depending on the extruded shapes, and there is also a problem that the molding accuracy of the members varies for each extruded shape. Furthermore, when natural aging progresses, there is a problem that the uniform elongation and local elongation of the extruded shape member are lowered, and the moldability and molding accuracy of the member are further lowered.
そして、更に、前記した、曲げ加工、断面の潰し加工、打抜き加工から選択される、塑性加工を伴う部材への成形加工では、残留応力が付加されやすく、この付加される残留応力が高いほど、その成形部位における耐ＳＣＣ性が著しく低下するという問題もある。 Further, in the forming process to the member with plastic working, which is selected from the bending process, the crushing process of the cross section, and the punching process described above, the residual stress is easily added, and the higher the applied residual stress is, There is also a problem that the SCC resistance at the molding site is significantly lowered.
前記自然時効した素材押出形材の成形性の改善のために、従来から、自然時効した素材押出形材を熱処理して、前記耐力などの強度を低下させる回復処理が行われている。 In order to improve the formability of the naturally aged material extruded profile, a recovery process has been conventionally performed in which the naturally aged material extruded profile is heat treated to reduce the strength such as the yield strength.
例えば、特許文献１では、航空機用フレームなどの製造方法が記載されている。そして、７０００系アルミニウム合金の素材押出形材あるいは素材板材につき、これを溶体化処理後に塑性加工する部品の成形方法において、成形直前に、加熱温度：１５０〜３５０℃で、加熱時間：３０秒〜５分間（急速加熱ができる場合は１７０〜２００℃×２０秒〜３分間）の、復元処理を行なうことによって溶体化処理後の自然時効によって硬化した材料を軟化させて成形性を確保し、自然時効の進度の違いによるスプリングバック量のばらつきを解消したのち成形している。 For example, Patent Document 1 describes a method for manufacturing an aircraft frame or the like. And in the molding method of the part which carries out plastic processing after the solution treatment of the material extruded profile or material plate of 7000 series aluminum alloy, immediately before molding, the heating temperature is 150 to 350 ° C., and the heating time is 30 seconds to The material cured by natural aging after solution treatment is softened by performing a restoration treatment for 5 minutes (170 to 200 ° C. × 20 seconds to 3 minutes if rapid heating is possible) to ensure moldability, Molded after eliminating variations in springback due to differences in aging progress.
また、特許文献２では、スピニング加工工程と該スピニング加工されたパイプを人工時効処理する高強度アルミニウム合金パイプの製造方法が記載されている。そして、素材である押出された７０００系などの析出硬化型の高硬度アルミニウム合金パイプを溶体化処理後、溶体化後に自然時効されたパイプを、スピニング加工によるローラと素材パイプとの摩擦発熱と、パイプの塑性変形による発熱、そしてアルミ材は熱伝導率が高いことを利用して、１５０℃〜２５０℃の温度範囲に局部的に短時間で昇温、自己冷却やスピニング加工工程での冷却効果で降温する復元処理を加味した、スピニング加工している。 Patent Document 2 describes a spinning process and a method for producing a high-strength aluminum alloy pipe in which the spun pipe is artificially aged. And after solution treatment of the precipitation hardening type high hardness aluminum alloy pipe such as extruded 7000 series which is the material, the pipe naturally aged after the solution treatment, friction heat generation between the roller and the material pipe by spinning, Heat generation due to plastic deformation of pipes and the high thermal conductivity of aluminum materials, the temperature rises in a short time locally in the temperature range of 150 ° C to 250 ° C, cooling effect in self-cooling and spinning process Spinning processing that takes into account the recovery process of lowering the temperature.
また、特許文献３では、長期の自然時効をしても優れた拡管加工性をそなえた自動二輪車のフロントフォークアウターチューブ材として好適な７０００系高力アルミニウム合金押出管の製造方法が記載されている。そして、アルミニウム合金押出管をＴ４調質した後、１０５℃〜２５０℃の温度で３０秒〜１８０分間熱処理し、該熱処理において、少なくとも１００℃から熱処理温度までの昇温速度を１℃／秒未満とする復元処理を行なうことが提案されている。その実施例では、２段時効後の引張強さ、耐力、伸びに優れ、応力腐食割れ寿命も優れるとしている。 Patent Document 3 describes a method for producing a 7000-type high-strength aluminum alloy extruded tube suitable as a front fork outer tube material for a motorcycle having excellent tube expansion workability even after long-term natural aging. . Then, after T4 tempering the aluminum alloy extruded tube, heat treatment is performed at a temperature of 105 ° C. to 250 ° C. for 30 seconds to 180 minutes, and in this heat treatment, the temperature increase rate from at least 100 ° C. to the heat treatment temperature is less than 1 ° C./second. It is proposed to perform the restoration process. In the examples, the tensile strength, proof stress and elongation after two-stage aging are excellent, and the stress corrosion cracking life is also excellent.
また、特許文献４は、同じくフロントフォークアウターチューブ用高力アルミニウム合金押出管の耐応力腐食割れ性を向上させるために、７０００系高力アルミニウム合金押出管を溶体化処理および焼入れし、室温で１００時間以上の時間自然時効させたのち、１５０〜２５０℃の温度で３０秒〜１０分間熱処理し、該熱処理において少なくとも１００℃から熱処理温度までの昇温速度を１℃／秒以上とした復元処理を行ない、最後に人工時効処理を行う手法が提案されている。 In addition, Patent Document 4 discloses that in order to improve the stress corrosion cracking resistance of a high-strength aluminum alloy extruded tube for a front fork outer tube, the 7000 series high-strength aluminum alloy extruded tube is subjected to solution treatment and quenching, and 100% at room temperature. After natural aging for at least a period of time, heat treatment is performed at a temperature of 150 to 250 ° C. for 30 seconds to 10 minutes, and in this heat treatment, a restoration treatment is performed at a rate of temperature increase from at least 100 ° C. to the heat treatment temperature of 1 ° C./second or more. A method for performing artificial aging treatment at the end is proposed.
これら従来の復元処理は、その加熱温度や、保持時間の長さなどの条件から推測すると、全て完全なＯ材処理になりやすい。すなわち、Ｏ材処理にならないようにためには、後述する通り、本発明の復元処理のように、特定の加熱速度による急熱、７０００系アルミニウム合金押出形材などの素材の特定の実体温度、特定のごく短時間の保持、特定の冷却速度での急冷などの諸条件を満足することが必要である。また、これらの処理条件を満たした上で、この復元処理による０．２％耐力の低下率や、導電率差の特性条件を満たすことが必要になる。しかし、これら従来の復元処理には、これらの条件の開示は勿論なく、必然的に完全なＯ材処理になる確率が高くなる。このため、復元処理によって耐力を一旦低下させたあとで、調質処理を施しても、その人工時効硬化処理によって向上させられる強度には大きな限界がある。ちなみに、これら従来の復元処理温度の記載は、通常の炉の雰囲気温度であって、実体温度ではないことが多い。 All of these conventional restoration processes are likely to be a complete O material treatment when estimated from conditions such as the heating temperature and the length of the holding time. That is, in order to avoid the O material treatment, as described later, as in the restoration treatment of the present invention, rapid heating by a specific heating rate, a specific actual temperature of a material such as a 7000 series aluminum alloy extruded shape, It is necessary to satisfy various conditions such as holding for a specific very short time and quenching at a specific cooling rate. In addition, after satisfying these processing conditions, it is necessary to satisfy the condition of 0.2% yield strength reduction due to the restoration processing and the characteristic difference of conductivity. However, these conventional restoration processes do not disclose these conditions, and the probability of inevitably becoming a complete O material process increases. For this reason, even if the tempering treatment is performed after the yield strength is once lowered by the restoration treatment, there is a great limit to the strength that can be improved by the artificial age hardening treatment. Incidentally, the description of these conventional restoration processing temperatures is an ordinary furnace atmosphere temperature, and not an actual temperature in many cases.
一方、特許文献２のような、スピニング加工によるローラと素材パイプとの摩擦発熱とパイプの塑性変形による発熱を利用した復元処理では、アルミニウム合金パイプに素材形状が限定され、押出形材などには適用できない。また、スピニング加工によるローラと素材パイプとの摩擦発熱とパイプの塑性変形による発熱の利用では、復元処理条件の制御が困難で、復元処理条件のばらつきが大きくなる。このため、素材の必要部位を、正確にかつ均一に復元処理することが難しい。 On the other hand, in the restoration process using the frictional heat generation between the roller and the material pipe by spinning processing and the heat generation by plastic deformation of the pipe as in Patent Document 2, the material shape is limited to the aluminum alloy pipe, Not applicable. In addition, when the frictional heat generated between the roller and the material pipe by the spinning process and the heat generated by the plastic deformation of the pipe are used, it is difficult to control the restoration processing conditions, and the variation in the restoration processing conditions increases. For this reason, it is difficult to restore a necessary portion of the material accurately and uniformly.
更に、これら従来技術では、７０００系高力アルミニウム合金押出形材の、溶体化などの調質後の自然時効による成形性の低下を問題としている。したがって、成形性を向上させる、成形前の復元処理については考慮されているものの、共通して、復元処理後の前記塑性加工を伴う部材への成形加工で付加される残留応力については全く考慮されていない。すなわち、復元処理によって残留応力が除去されたとしても、また、それによって成形性が向上したとしても、この復元処理後の前記曲げ加工、断面の潰し加工、打抜き加工などの塑性加工を伴う部材への成形加工では、依然、大きな残留応力が付加される。 Furthermore, these conventional techniques have a problem of deterioration of formability due to natural aging after tempering such as solution treatment of 7000 series high-strength aluminum alloy extruded shapes. Therefore, although the restoration process before molding for improving the moldability is considered, in common, the residual stress applied in the molding process with the plastic processing after the restoration process is completely considered. Not. That is, even if the residual stress is removed by the restoration process, and even if the moldability is thereby improved, the member is subjected to plastic working such as the bending process, the crushing process of the cross section, and the punching process after the restoration process. In this molding process, a large residual stress is still applied.
しかも、この残留応力は、成形後の部材が溶体化および焼入れ処理されない場合には除去できない。このため、前記成形加工によって、この残留応力が付加された部材の成形部位における耐ＳＣＣ性低下の問題に対して、これら従来技術は共通して未解決である。しかも、この耐ＳＣＣ性が低下する傾向は、７０００系アルミニウム合金部材が高強度となるほど顕著となる。 Moreover, this residual stress cannot be removed when the molded member is not subjected to solution treatment and quenching treatment. For this reason, these conventional techniques have not been solved in common with respect to the problem of the SCC resistance deterioration at the molding site of the member to which the residual stress is applied by the molding process. And the tendency for this SCC resistance to fall becomes so remarkable that a 7000 series aluminum alloy member becomes high intensity | strength.
本発明は、かかる問題に鑑みなされたもので、あとの前記曲げ加工、断面の潰し加工、打抜き加工などの塑性加工を伴う部材への成形加工によって付加される残留応力を小さくでき、耐力を一旦低下させたあとでも調質処理を施し、その人工時効硬化処理によって強度を大きく向上できる、高強度７０００系アルミニウム合金部材の製造方法および高強度７０００系アルミニウム合金部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 can reduce the residual stress applied by the forming process to the member accompanied by the plastic processing such as the bending process, the crushing process of the cross section, and the punching process later, and the proof stress is once increased. An object of the present invention is to provide a method for producing a high-strength 7000 series aluminum alloy member and a high-strength 7000 series aluminum alloy member, which can be subjected to a tempering treatment even after being lowered and the strength can be greatly improved by the artificial age hardening treatment.
上記目的を達成するため、本発明の高強度７０００系アルミニウム合金部材の製造方法の要旨は、質量％で、Ｚｎ：５．０〜８．０％、Ｍｇ：０．３〜２．０％、Ｃｕ：０．０５〜０．５％を含有し、さらに、Ｍｎ：０．０１〜０．３％、Ｃｒ：０．０１〜０．３％、Ｚｒ：０．０１〜０．３％の一種または二種以上を含有し、残部が不可避的不純物およびアルミニウムからなる組成を有する７０００系アルミニウム合金素材を、鋳塊からの塑性加工によって製造後に、自然時効以外は人工的に調質することなく復元処理を行い、この復元処理を、０．５℃／秒以上の加熱速度によって急熱し、２００℃を超え、５００℃以下の実体温度範囲にて２０秒未満の短時間だけ保持した後に、室温まで０．５℃／秒以上の冷却速度で急冷して、この急冷直後の前記素材の０．２％耐力を１２０ＭＰａ以下とするとともに、この急冷直後の前記素材の導電率と、前記復元処理直前の前記素材の導電率との差を５％ＩＡＣＳ未満とし、この復元処理の前記室温までの急冷終了後から１時間以内に、この復元処理以外は人工的に調質することなく、曲げ加工、断面の潰し加工、打抜き加工から選択される残留応力の発生を伴う成形加工を行って部材化し、この部材に対して、溶体化および焼入れ処理することなく人工時効処理し、この人工時効処理後の部材の０．２％耐力を３００ＭＰａ以上とするとともに、前記成形加工を受けた部材位置における残留応力を１６０ＭＰａ以下としたことである。 In order to achieve the above object, the gist of the manufacturing method of the high-strength 7000 series aluminum alloy member of the present invention is mass%, Zn: 5.0-8.0%, Mg: 0.3-2.0% Cu: 0.05 to 0.5%, Mn: 0.01 to 0.3%, Cr: 0.01 to 0.3%, Zr: 0.01 to 0.3% Alternatively, after manufacturing a 7000 series aluminum alloy material containing two or more types and the balance consisting of inevitable impurities and aluminum by plastic working from an ingot, it is restored without artificial tempering except for natural aging This restoration process is rapidly heated at a heating rate of 0.5 ° C./second or more, held for a short time of less than 20 seconds in an actual temperature range exceeding 200 ° C. and 500 ° C. quenched with 0.5 ° C. / sec or more cooling rate, the With the following 120MPa 0.2% yield strength of the material immediately after cooling, and this and conductivity of the material immediately after quenching, the difference between the conductivity of the material immediately before the restoration process to less than 5% IACS, the Within one hour after the completion of the rapid cooling to the room temperature of the restoration process, there is a residual stress selected from bending, cross-section crushing, and punching without artificial conditioning except for the restoration process. A member is formed by performing a forming process, and the member is subjected to artificial aging treatment without solution treatment and quenching treatment, and the 0.2% proof stress of the member after the artificial aging treatment is set to 300 MPa or more. The residual stress at the position of the member that has been subjected to is set to 160 MPa or less.
また、上記目的を達成するための本発明の高強度７０００系アルミニウム合金部材の要旨は、質量％で、Ｚｎ：５．０〜８．０％、Ｍｇ：０．３〜２．０％、Ｃｕ：０．０５〜０．５％を含有し、さらに、Ｍｎ：０．０１〜０．３％、Ｃｒ：０．０１〜０．３％、Ｚｒ：０．０１〜０．３％の一種または二種以上を含有し、残部が不可避的不純物およびアルミニウムからなる組成を有する７０００系アルミニウム合金押出形材が復元処理されて、この復元処理後の急冷直後の前記押出形材の０．２％耐力が１２０ＭＰａ以下とされるとともに、この急冷直後の前記押出形材の導電率と、前記復元処理直前の前記押出形材の導電率との差が５％ＩＡＣＳ未満とされた上で、曲げ加工、断面の潰し加工、打抜き加工から選択される残留応力の発生を伴う成形加工によって部材化されるとともに、この成形加工の後に溶体化および焼入れ処理されることなく人工時効処理が施された７０００系アルミニウム合金部材であって、０．２％耐力が３００ＭＰａ以上であるとともに、前記成形加工を受けた部材位置における残留応力が１６０ＭＰａ以下であることである。 Moreover, the summary of the high-strength 7000 series aluminum alloy member of this invention for achieving the said objective is the mass%, Zn: 5.0-8.0%, Mg: 0.3-2.0%, Cu : 0.05-0.5%, and Mn: 0.01-0.3%, Cr: 0.01-0.3%, Zr: 0.01-0.3% A 7000 series aluminum alloy extruded shape that contains two or more types and the balance is composed of inevitable impurities and aluminum is restored, and the 0.2% proof stress of the extruded shape immediately after quenching after the restoration treatment Is 120 MPa or less, and the difference between the conductivity of the extruded shape immediately after the rapid cooling and the conductivity of the extruded shape immediately before the restoration treatment is less than 5% IACS, crushing processing of the cross-section, the occurrence of residual stress is selected from stamped It is a 7000 series aluminum alloy member that is formed into a member by the accompanying forming process and is subjected to artificial aging treatment without solution treatment and quenching treatment after the forming process, and 0.2% proof stress is 300 MPa or more And it is that the residual stress in the member position which received the said shaping | molding process is 160 Mpa or less.
本発明では、前記７０００系アルミニウム合金素材を、その実体温度が比較的高温で、かつ絶対的に短時間などの特定条件での復元処理をすることによって、あとの成形加工によって付加される残留応力が低減されることを知見した。前記従来の復元処理は、前記した通り、Ｏ材処理にならないようにための、本発明の復元処理のような緒条件（特定の加熱速度による急熱、素材の特定の実体温度、特定のごく短時間の保持、特定の冷却速度での急冷）を満足することについての認識がない。また、これらの処理条件を満たした上で、この復元処理による０．２％耐力の低下率や、導電率差の特性条件を満たすことが必要との認識もない。したがって、これら従来の復元処理では必然的に完全なＯ材処理になる確率が高くなる。 In the present invention, the 7000 series aluminum alloy material is subjected to a restorative treatment under a specific condition such as a relatively high temperature and an absolute short time, whereby a residual stress applied by a subsequent forming process is applied. Was found to be reduced. As described above, the conventional restoration process is performed under the same conditions as those of the restoration process of the present invention (rapid heating at a specific heating rate, a specific substance temperature of a material, a specific value) There is no recognition of satisfying short-time holding, rapid cooling at a specific cooling rate). Further, there is no recognition that it is necessary to satisfy the condition of the 0.2% yield strength reduction or the conductivity difference due to the restoration process after satisfying these processing conditions. Therefore, these conventional restoration processes inevitably increase the probability of complete O material treatment.
通常、溶体化処理後に室温あるいはそれ以下の温度で保管された材料（Ｔ４材)で、この溶体化処理後に自然時効された材料は、Ｇ．Ｐ．ゾーン（析出物が形成される初期段階の溶質元素の集合体）あるいは極めて微細な中間相の析出によって硬化している。前記した、通常の復元処理は、この溶体化処理後に自然時効した材料を１５０〜３５０℃の温度に加熱することにより、前記微細な析出物をマトリックス中に再固溶させる処理であり、再溶体化処理するのと類似の作用を有し、軟質化のＯ材処理をしている。 Usually, a material (T4 material) stored at room temperature or lower after solution treatment and naturally aged after this solution treatment is G.S. P. It is hardened by precipitation of zones (aggregates of solute elements in the initial stage where precipitates are formed) or very fine intermediate phases. The normal restoration process described above is a process in which the fine precipitates are re-dissolved in the matrix by heating the naturally aged material after the solution treatment to a temperature of 150 to 350 ° C. It has an effect similar to that of softening treatment, and is treated with softening O material.
しかし、本発明では、これら従来の復元処理とは違い、７０００系アルミニウム合金押出形材素材を、鋳塊からの熱間押出（塑性加工）によって製造後には、自然時効による硬化以外は、復元処理を行う。そして、この復元処理も、急速な加熱（０．５℃／秒以上の加熱速度）によって、７０００系アルミニウム合金押出形材素材の実体温度を２００℃を超え、５００℃以下として、その温度範囲に２０秒未満のごく短時間だけ保持し、更に室温まで急冷（０．５℃／秒以上の冷却速度）する。 However, in the present invention, unlike these conventional restoration processes, after the 7000 series aluminum alloy extruded shape material is manufactured by hot extrusion (plastic processing) from the ingot, the restoration process is performed except for hardening by natural aging. I do. This restoration process is also carried out by rapid heating (heating rate of 0.5 ° C./second or more), and the actual temperature of the 7000 series aluminum alloy extruded shape material exceeds 200 ° C. and is 500 ° C. or less. Hold for a very short time of less than 20 seconds, and then rapidly cool to room temperature (cooling rate of 0.5 ° C./second or more).
これによって、７０００系アルミニウム合金押出形材素材の、この急冷直後の０．２％耐力を１２０ＭＰａ以下に低下させるが、本発明の復元処理は、軟質化のためのＯ材処理とは異なり、成形後の人工時効硬化処理で、部材強度を０．２％耐力で３００ＭＰａ以上に確保できる。ちなみに、この復元処理が長時間となれば、軟質化のためのＯ材処理となって、成形時に付与される残留応力は低減されるが、成形後の人工時効硬化処理で、部材強度を０．２％耐力で３００ＭＰａ以上に確保できなくなる。 As a result, the 0.2% proof stress immediately after the rapid cooling of the 7000 series aluminum alloy extruded shape material is reduced to 120 MPa or less, but the restoration treatment of the present invention is different from the O material treatment for softening. In the later artificial age hardening treatment, the member strength can be secured to 300 MPa or more with a 0.2% proof stress. Incidentally, if this restoration process takes a long time, it becomes an O material treatment for softening and the residual stress applied during molding is reduced, but the strength of the member is reduced to 0 by the artificial age hardening treatment after molding. .2% proof stress cannot be secured above 300 MPa.
また、本発明では、部材への成形後には溶体化および焼入れ処理することなく人工時効硬化処理を行う。すなわち、本発明の復元処理によれば、その後の成形時に付与される残留応力が低減された上で、部材への成形後、溶体化および焼入れ処理されることなく、人工時効硬化処理のみで、部材強度を０．２％耐力で３００ＭＰａ以上に確保でき、前記成形加工を受けた部材位置における残留応力を１６０ＭＰａ以下に抑制することができる。 Moreover, in this invention, after shaping | molding to a member, an artificial age hardening process is performed without performing solution treatment and hardening process. That is, according to the restoration process of the present invention, after the residual stress applied at the time of subsequent molding is reduced, without being subjected to solution treatment and quenching process after molding into a member, only by artificial age hardening treatment, The member strength can be secured to 300 MPa or more with a 0.2% proof stress, and the residual stress at the member position subjected to the forming process can be suppressed to 160 MPa or less.
したがって、本発明によれば、自然時効した高強度の７０００系アルミニウム合金押出形材であっても、また、曲げ加工、断面の潰し加工、打抜き加工から選択される残留応力の発生を伴う成形加工によって部材化された高強度７０００系アルミニウム合金部材であっても、この部材に対して、溶体化および焼入れ処理することなく人工時効硬化処理を行った際の、この調質後の部材の０．２％耐力を３００ＭＰａ以上とできる。そして、成形後の部材が溶体化および焼入れ処理されず、成形後のこれら調質によって成形によって付与された残留応力を除去できない場合でも、前記成形加工を受けた部材位置における残留応力を１６０ＭＰａ以下に抑制することができる。 Therefore, according to the present invention, even a high-strength 7000 series aluminum alloy extruded shape that is naturally aged is also formed with the generation of residual stress selected from bending, cross-sectional crushing, and punching. Even if it is a high-strength 7000 series aluminum alloy member made into a member by the above-mentioned method, when this member is subjected to artificial age hardening treatment without solution treatment and quenching treatment, 0. The 2% proof stress can be 300 MPa or more. Even when the molded member is not subjected to solution treatment and quenching treatment, and the residual stress imparted by molding cannot be removed by these tempering after molding, the residual stress at the member position subjected to the molding process is 160 MPa or less. Can be suppressed.
また、自然時効硬化の程度や進行の仕方によって強度が異なる、すなわち強度やスプリングバック量がばらつく問題も解消され、押出形材の機械的性質やスプリングバック量の均一化が図れる。また、自然時効が進展した場合の押出形材の均一伸びや局部伸びの低下も解消され、この均一伸びや局部伸びが向上するとともに部材への成形性や成形精度が更に向上する。 Further, the problem that the strength varies depending on the degree of natural age hardening and the manner of progress, that is, the problem that the strength and the amount of springback vary, is solved, and the mechanical properties and the amount of springback of the extruded shape can be made uniform. In addition, the uniform elongation and local elongation of the extruded profile when natural aging progresses are also eliminated, and the uniform elongation and local elongation are improved, and the moldability and molding accuracy of the member are further improved.
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。なお、以下の記載は、７０００系アルミニウム合金素材として、鋳塊を熱間押出して製造した押出形材を例にして説明する。ただ、各条件の意義は、鋳塊を熱間圧延、冷間圧延して製造した圧延板素材の場合でも同様である。 Hereinafter, embodiments of the present invention will be specifically described in order for each requirement. In addition, the following description demonstrates as an example the extrusion shape member manufactured by extruding an ingot hot as a 7000 series aluminum alloy raw material. However, the significance of each condition is the same even in the case of a rolled sheet material manufactured by hot rolling and cold rolling an ingot.
組成：
本発明における７０００系アルミニウム合金押出形材（素材）は、ＪＩＳ規格およびＡＡ規格を含むＡｌ−Ｚｎ−Ｍｇ系組成あるいはＡｌ−Ｚｎ−Ｍｇ−Ｃｕ系組成である。但し、部材としての要求される高強度を満たすためには、通常の調質Ｔ５〜Ｔ７の人工時効処理条件である１２０〜１６０℃×６〜１６ｈｒの範囲で、この人工時効処理後の部材強度を０．２％耐力で３００ＭＰａ以上、好ましくは４００ＭＰａ以上とする必要がある。
composition:
The 7000 series aluminum alloy extruded profile (raw material) in the present invention has an Al—Zn—Mg series composition or an Al—Zn—Mg—Cu series composition including JIS standards and AA standards. However, in order to satisfy the required high strength as a member, the strength of the member after this artificial aging treatment is within the range of 120 to 160 ° C. × 6 to 16 hours, which is a normal aging treatment condition of temper T5 to T7. Must be 300 MPa or more, preferably 400 MPa or more with a 0.2% proof stress.
このための好ましい７０００系アルミニウム合金押出形材（素材）組成は、質量％で、Ｚｎ：５．０〜８．０％、Ｍｇ：０．３〜２．０％、Ｃｕ：０．０５〜０．５％を含有し、さらに、Ｍｎ：０．０１〜０．３％、Ｃｒ：０．０１〜０．３％、Ｚｒ：０．０１〜０．３％の一種または二種以上を含有し、残部が不可避的不純物およびアルミニウムからなる組成とする。 A preferable 7000 series aluminum alloy extruded shape (material) composition for this purpose is, by mass, Zn: 5.0 to 8.0%, Mg: 0.3 to 2.0%, Cu: 0.05 to 0. 0.5%, and further contains one or more of Mn: 0.01 to 0.3%, Cr: 0.01 to 0.3%, Zr: 0.01 to 0.3%. The balance is composed of inevitable impurities and aluminum.
ここで、成形性や耐食性あるいは溶接性などの素材あるいは部材としての諸特性を低下させないために、前記不可避的不純物として、溶解原料としての地金やスクラップなどから必然的に混入する、Ｆｅ、Ｓｉをそれぞれ０．２５％以下、Ｔｉを０．０５％以下とすることが好ましい。 Here, in order not to deteriorate various properties as materials or members such as formability, corrosion resistance, or weldability, Fe, Si, which is inevitably mixed as a melting raw material from metal or scrap as a raw material, Each is preferably 0.25% or less, and Ti is preferably 0.05% or less.
Ｚｎは強度を向上させる主要元素であり、その好ましい含有範囲は５．０〜８．０％である。下限未満では強度が不十分になり、上限を超えて含有されると耐ＳＣＣ性（耐応力腐食割れ性）の顕著な低下を招く。さらに好ましい含有範囲は６．２〜６．８％である。 Zn is a main element for improving the strength, and its preferable content range is 5.0 to 8.0%. If the content is less than the lower limit, the strength becomes insufficient. If the content exceeds the upper limit, the SCC resistance (stress corrosion cracking resistance) is significantly lowered. A more preferable content range is 6.2 to 6.8%.
Ｍｇも強度を向上させる主要元素であり、その好ましい含有範囲は０．３〜２．０％である。下限未満では強度が不十分になり、上限を超えて含有されると耐ＳＣＣ性の低下を招く。さらに好ましい含有範囲は０．６〜１．５％である。 Mg is also a main element for improving the strength, and its preferable content range is 0.3 to 2.0%. If it is less than the lower limit, the strength becomes insufficient, and if it exceeds the upper limit, the SCC resistance is lowered. A more preferable content range is 0.6 to 1.5%.
Ｃｕは強度も向上させる主要元素であり、その好ましい含有範囲は０．０５〜０．５％である。下限未満では強度が不十分になり、上限を超えて含有されると押出加工性の低下を招く。さらに好ましい含有範囲は０．０８〜０．２％である。 Cu is a main element that also improves the strength, and its preferred content range is 0.05 to 0.5%. If it is less than the lower limit, the strength becomes insufficient, and if it exceeds the upper limit, the extrusion processability is lowered. A more preferable content range is 0.08 to 0.2%.
Ｍｎ、Ｃｒ、Ｚｒは選択的に含有される元素であり、一種または二種以上を含有することで、いずれも素材の結晶組織を微細化あるいは繊維状にし、耐ＳＣＣ性を向上させる。それぞれ好ましい含有範囲は、Ｍｎ：０．０１〜０．３％、Ｃｒ：０．０１〜０．３％、Ｚｒ：０．０１〜０．３％である。いずれも上限を超えて含有されると粗大な金属間化合物を形成し、延性が低下するとともに成形性の低下を招く。 Mn, Cr, and Zr are elements that are selectively contained, and by containing one or two or more of them, any of them makes the crystal structure of the material finer or fibrous and improves the SCC resistance. The preferable content ranges are Mn: 0.01 to 0.3%, Cr: 0.01 to 0.3%, and Zr: 0.01 to 0.3%, respectively. When both are contained exceeding the upper limit, a coarse intermetallic compound is formed, resulting in a decrease in ductility and a decrease in moldability.
ＦｅおよびＳｉは不純物として含有される元素であり、好ましい含有範囲はＦｅ：０．２５％以下、Ｓｉ：０．２５％以下である。上限を越えて含有されると延性が低下するとともに拡管加工性の低下を招く。さらに好ましい含有範囲は、Ｆｅ：０．２０％以下、Ｓｉ：０．２０％以下であり、最も好ましい含有範囲はＦｅ：０．１５％以下、Ｓｉ：０．１５％以下である。 Fe and Si are elements contained as impurities, and preferable content ranges are Fe: 0.25% or less and Si: 0.25% or less. When the content exceeds the upper limit, ductility is lowered and tube expansion workability is lowered. Further preferable content ranges are Fe: 0.20% or less, Si: 0.20% or less, and most preferable content ranges are Fe: 0.15% or less, Si: 0.15% or less.
製造方法：
７０００系アルミニウム合金素材として押出形材を例にして説明する。なお、熱処理における記載温度は全て実体温度であって、炉の雰囲気温度ではない。
Production method:
An explanation will be given by taking an extruded profile as an example of the 7000 series aluminum alloy material. Note that all described temperatures in the heat treatment are actual temperatures, not the furnace atmosphere temperature.
（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。
(Melting, casting)
First, in the melting and casting process, a molten aluminum alloy melt-adjusted within the above-mentioned 7000 series component composition range is cast by appropriately selecting a normal melting casting method such as a semi-continuous casting method (DC casting method). And
（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４７０〜５６５℃の範囲で均質化熱処理（均熱処理）し、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。均熱処理温度は４７０〜５６５℃の範囲、均質化時間は２時間以上の範囲から選択される。この均熱処理温度が高すぎると、形材組織中の分散粒子が粗大化し、結晶粒を微細化、高強度化できない。一方、この均熱処理温度が低すぎても、ビレット組織の均質化ができない。
(Homogenization heat treatment)
Prior to hot extrusion, the cast aluminum alloy billet (ingot) is subjected to homogenization heat treatment (soaking) in the range of 470 to 565 ° C. to homogenize the structure (segregation within crystal grains in the ingot structure). Etc.). The soaking temperature is selected from the range of 470 to 565 ° C., and the homogenization time is selected from the range of 2 hours or more. If the soaking temperature is too high, the dispersed particles in the shape structure become coarse, and the crystal grains cannot be refined and strengthened. On the other hand, even if the soaking temperature is too low, the billet structure cannot be homogenized.
（熱間押出）
この均質化後の７０００系アルミニウム合金ビレットを熱間押出（直接押出、間接押出）するが、押出形材の再結晶粒層を抑制し、組織を微細化、均質化させる条件にて熱間押出することが好ましい。ビレットの押出開始温度は好ましくは３５０〜４５０℃とする。
(Hot extrusion)
This homogenized 7000 series aluminum alloy billet is hot-extruded (direct extrusion or indirect extrusion), but it is hot-extruded under conditions that suppress the recrystallized grain layer of the extruded shape and refine and homogenize the structure. It is preferable to do. The extrusion start temperature of the billet is preferably 350 to 450 ° C.
また、これら熱間押出直後の冷却については、溶体化域の温度（溶体化温度）での押出（押出機）出側温度から、空冷さらには水冷などの急冷（オンライン焼入れ）することが、押出形材組織の表面の再結晶組織や、内部の加工組織の結晶粒粗大化防止の点で好ましい。ちなみに、このような押出直後に（押出機の出側で）押出工程上で連続してオンラインにて行われる急冷あるいは焼入れ処理は、本発明でいう調質には含まれない。したがって、本発明でいう、自然時効による硬化以外は、溶体化処理などの調質することなく復元処理を行うとは、押出工程とは別途のオフラインにて、押出形材素材を再加熱して行われる溶体化および焼入れ処理などの調質することなく、復元処理を行うことである。 As for the cooling immediately after the hot extrusion, it is possible to carry out rapid cooling (on-line quenching) such as air cooling and water cooling from the extrusion (extruder) outlet temperature at the temperature of the solution zone (solution temperature). This is preferable in terms of preventing recrystallization structure on the surface of the shape material structure and coarsening of crystal grains in the internal processing structure. Incidentally, such quenching or quenching process performed on-line continuously on the extrusion process immediately after extrusion (on the exit side of the extruder) is not included in the tempering referred to in the present invention. Therefore, in the present invention, except for curing by natural aging, the restoration process is performed without tempering such as a solution treatment, and the extruded shape material is reheated off-line separate from the extrusion process. The restoration process is performed without any tempering such as solution treatment and quenching process.
（復元処理）
本発明の復元処理は、これら従来の復元処理とは違い、７０００系アルミニウム合金押出形材素材を、鋳塊からの熱間押出（塑性加工）によって製造後に、自然時効による硬化以外は、溶体化および焼入れ処理などの調質することなく復元処理を行う。言い換えると、自然時効（室温時効）した７０００系アルミニウム合金押出形材素材に対して、本発明の復元処理を施してこそ、その後の成形加工時に付与される残留応力が低減された上で、成形後の調質で部材強度を０．２％耐力で３００ＭＰａ以上に確保できる効果が得られる。
(Restore process)
Unlike these conventional restoration processes, the restoration process of the present invention is a solution of a 7000 series aluminum alloy extruded shape material, except for hardening by natural aging after manufacturing by hot extrusion (plastic processing) from an ingot. And restoration processing is performed without tempering such as quenching. In other words, it is only after the restoration treatment of the present invention is applied to the extruded material of the 7000 series aluminum alloy that has been naturally aged (room temperature aging), and the residual stress applied during the subsequent molding process is reduced. The effect of securing the member strength to 300 MPa or more with 0.2% proof stress can be obtained by subsequent tempering.
（復元処理条件）
そして、この復元処理の条件も、この復元処理による前記効果の発現のために重要である。すなわち、０．５℃／秒以上の加熱速度による急速加熱（急熱）によって、７０００系アルミニウム合金押出形材素材の実体温度を２００℃を超え、５００℃以下まで加熱し、この温度範囲に２０秒未満のごく短時間だけ保持する。そして、保持後直ちに、室温まで０．５℃／秒以上の冷却速度で、強制的に急冷（空冷、水冷、ミスト冷却）する。
(Restore processing conditions)
The conditions for the restoration process are also important for the manifestation of the effect by the restoration process. That is, the actual temperature of the extruded material of the 7000 series aluminum alloy exceeds 200 ° C. to 500 ° C. or less by rapid heating (rapid heating) at a heating rate of 0.5 ° C./second or more. Hold for a very short time of less than a second. Immediately after the holding, rapid cooling (air cooling, water cooling, mist cooling) is forced to room temperature at a cooling rate of 0.5 ° C./second or more.
７０００系アルミニウム合金押出形材素材の実体温度が２００℃未満では、復元処理が不十分となって、特に、成形加工性が向上せず、付与される残留応力が高くなる。また、保持時間が２０秒以上に長すぎる、あるいは加熱速度が０．５℃／秒未満と遅い（保持時間が長くなる）と、完全なＯ材処理（焼きなまし処理）となって、人工時効処理後の強度が０．２％耐力で３００ＭＰａ以上に向上しない。 When the actual temperature of the extruded material of the 7000 series aluminum alloy is less than 200 ° C., the restoration process is insufficient, and particularly, the formability is not improved and the applied residual stress is increased. Further, if the holding time is too long for 20 seconds or more, or if the heating rate is slow (less than 0.5 ° C./second) (holding time becomes longer), the processing becomes complete O material treatment (annealing treatment) and artificial aging treatment The later strength is not improved to 300 MPa or more at 0.2% proof stress.
ちなみに、この復元処理における温度管理を炉の雰囲気温度で制御しようとすると、形材素材の実体としての保持時間が長めに外れたり、あるいは形材素材の実体としての温度が低めに外れたりしやすい。急速加熱（急熱）の加熱速度の制御は形材素材の大きさに合わせた炉のヒーターで制御可能で、前記実体温度保持時間は押出形材素材の炉からの取り出し時間（取り出しタイミング）で制御可能である。また、この取り出し直後からの室温までの強制的な急冷による冷却速度の制御は、形材素材の大きさに合わせた、空冷、水冷、ミスト冷却などの冷媒の使用量（形材素材への吹きかけ量あるいは浸漬量）によって可能である。この際、本発明で言う室温とは、数℃、０℃あるいは０℃以下などの、いわゆる１８〜２０℃程度の室温以下の温度（への冷却）を含みうる。 By the way, if you try to control the temperature control in this restoration process with the furnace ambient temperature, the holding time as the shape material entity will be long, or the temperature as the shape material entity will be low. . The heating speed of rapid heating (rapid heating) can be controlled by a furnace heater that matches the size of the shape material, and the actual temperature holding time is the removal time (removal timing) of the extruded shape material from the furnace. It can be controlled. In addition, the cooling rate control by forced rapid cooling to room temperature immediately after the removal is based on the amount of refrigerant used (air cooling, water cooling, mist cooling, etc.) The amount or the amount of immersion). In this case, the room temperature referred to in the present invention may include a temperature (cooling to room temperature) of about 18 to 20 ° C. or less, such as several degrees C., 0 ° C. or 0 ° C. or less.
これによって、７０００系アルミニウム合金押出形材素材の、この急冷直後の０．２％耐力を１２０ＭＰａ以下に低下させるが、本発明の復元処理は、軟質化のためのＯ材処理とは異なり、成形後の調質における人工時効硬化処理で、部材強度を０．２％耐力で３００ＭＰａ以上に確保できる。前記復元処理の急冷直後の０．２％耐力は、本発明の復元処理が効果的に行われたか否かの重要な目安であり、本発明でも前記急冷直後から直ちに自然時効が始まるため、前記急冷直後の０．２％耐力が１２０ＭＰａを超えていては、前記成形加工における諸効果が得られない。 As a result, the 0.2% proof stress immediately after the rapid cooling of the 7000 series aluminum alloy extruded shape material is reduced to 120 MPa or less, but the restoration treatment of the present invention is different from the O material treatment for softening. By the artificial age hardening treatment in the subsequent tempering, the member strength can be secured to 300 MPa or more with a 0.2% proof stress. The 0.2% yield strength immediately after the rapid cooling of the restoration process is an important measure as to whether or not the restoration process of the present invention was effectively performed, and since natural aging starts immediately after the rapid cooling in the present invention, If the 0.2% proof stress immediately after quenching exceeds 120 MPa, various effects in the molding process cannot be obtained.
更に、本発明者らの知見によれば、この復元処理が効果的に行われたか否かの、もうひとつの重要な目安として、前記復元処理における急冷直後の前記押出形材素材の導電率と、前記復元処理直前の前記押出形材素材の導電率との差がある。一般的に、前記復元処理によって、復元処理直後の導電率は復元前よりも高くなる。ただ、本発明の復元処理と、従来の復元処理での完全なＯ材処理（焼きなまし処理）の場合では、この導電率差は大きく異なる。すなわち、本発明の復元処理後（急冷直後）の導電率は、復元処理直前のＴ１材（自然時効材）の導電率よりも必ず５％ＩＡＣＳ未満、多くは１〜３％ＩＡＣＳの範囲で高くなり、本発明の復元処理での導電率差は必ず５％ＩＡＣＳ未満、好ましくは１〜３％ＩＡＣＳの範囲となる。このように、導電率差が５％ＩＡＣＳ未満、好ましくは１〜３％ＩＡＣＳの範囲の場合に、前記成形における諸効果が得られ、復元処理が確実に効果的に行われる。 Furthermore, according to the knowledge of the present inventors, another important measure as to whether or not the restoration process has been performed effectively is the conductivity of the extruded profile material immediately after the rapid cooling in the restoration process. There is a difference from the conductivity of the extruded shape material immediately before the restoration process. Generally, due to the restoration process, the conductivity immediately after the restoration process is higher than that before the restoration process. However, in the case of the restoration process of the present invention and the complete O material process (annealing process) in the conventional restoration process, this conductivity difference is greatly different. That is, the conductivity after the restoration process (immediately after quenching) of the present invention is always less than 5% IACS, and often higher in the range of 1 to 3% IACS than the conductivity of the T1 material (natural aging material) just before the restoration process. Thus, the conductivity difference in the restoration process of the present invention is always less than 5% IACS, preferably in the range of 1 to 3% IACS. As described above, when the conductivity difference is less than 5% IACS, preferably in the range of 1 to 3% IACS, various effects in the molding can be obtained, and the restoration process is reliably and effectively performed.
これに対して、従来の復元処理後の導電率は、処理前の導電率よりも必ず５％ＩＡＣＳ以上高くなり、従来の復元処理での完全なＯ材処理の場合の導電率差は必ず５％ＩＡＣＳ以上となる。この従来の復元処理での完全なＯ材処理のように、前記導電率差が５％ＩＡＣＳ以上となった場合、完全焼きなましのＯ材に近く、あるいは、そのＯ材となって、前記成形における諸効果が得られなくなる。したがって、７０００系アルミニウム合金押出形材素材の復元処理において、この復元処理の効果を確実に達成するためには、復元処理後の急冷直後の０．２％耐力を１２０ＭＰａ以下とするとともに、前記導電率差を５％ＩＡＣＳ未満とすること（両方満足すること）が好ましい。 On the other hand, the conductivity after the conventional restoration process is always 5% IACS or more higher than the conductivity before the treatment, and the conductivity difference in the case of the complete O material treatment in the conventional restoration process is always 5%. % IACS or higher. When the conductivity difference is 5% IACS or more as in the case of the complete O material processing in the conventional restoration process, the O material is close to the fully annealed O material, or becomes the O material, in the molding. Various effects cannot be obtained. Therefore, in order to reliably achieve the effect of the restoration process in the restoration process of the 7000 series aluminum alloy extruded shape material, the 0.2% proof stress immediately after the quenching after the restoration process is set to 120 MPa or less, and the conductive It is preferable that the rate difference is less than 5% IACS (both are satisfied).
以上の条件で行う発明の復元処理によれば、７０００系アルミニウム合金押出形材を、曲げ加工、断面の潰し加工、打抜き加工から選択される残留応力の発生を伴う成形加工によって部材化された高強度７０００系アルミニウム合金部材であっても、この部材に対して調質を行った際の、この調質後の部材の０．２％耐力を３００ＭＰａ以上とできるとともに、前記成形加工を受けた部材位置における残留応力を１６０ＭＰａ以下に抑制することができる。 According to the restoration process of the invention performed under the above conditions, the 7000 series aluminum alloy extruded profile is made into a member by a forming process accompanied by generation of residual stress selected from bending process, crushing process of cross section, and punching process. Even if it is a strength 7000 series aluminum alloy member, the 0.2% proof stress of the tempered member when it is tempered can be set to 300 MPa or more, and the member subjected to the forming process The residual stress at the position can be suppressed to 160 MPa or less.
ただ、これらの復元処理条件によって後述する諸効果が得られる理由や、これらの復元処理条件から外れた場合に後述する諸効果が得られない理由は、現在のところ不明である。しかし、この復元処理が前記した時間よりも長時間となる、あるいは前記した急熱や急冷条件が外れるなどすれば、従来の軟質化のためのＯ材処理と変わらなくなり、成形性は向上するものの、成形時に付与される残留応力は低減されず、成形後の調質における人工時効硬化処理で、部材強度を０．２％耐力で３００ＭＰａ以上に確保できなくなる。 However, the reason why various effects described later can be obtained by these restoration processing conditions, and the reason why various effects described later cannot be obtained when deviating from these restoration processing conditions is unknown. However, if this restoration process is longer than the above-mentioned time, or if the above-mentioned rapid heating and quenching conditions are removed, the process will be the same as the conventional O-material treatment for softening, but the moldability is improved. The residual stress applied at the time of molding is not reduced, and the member strength cannot be secured at 300 MPa or more with 0.2% proof stress by the artificial age hardening treatment in the tempering after molding.
本発明の復元処理によれば、自然時効した高強度の７０００系アルミニウム合金押出形材であっても、また、曲げ加工、断面の潰し加工、打抜き加工から選択される残留応力の発生を伴う成形加工によって部材化された高強度７０００系アルミニウム合金部材であっても、この部材に対して調質を行った際の、この調質後の部材の０．２％耐力を３００ＭＰａ以上とできるとともに、前記成形加工を受けた部材位置における残留応力を１６０ＭＰａ以下に抑制することができる。 According to the restoration process of the present invention, even a naturally-aged and high-strength 7000 series aluminum alloy extruded shape is formed with the occurrence of residual stress selected from bending, crushing of the cross section, and punching. Even if it is a high-strength 7000 series aluminum alloy member made into a member by processing, the 0.2% proof stress of this tempered member when tempering this member can be 300 MPa or more, Residual stress at the position of the member subjected to the forming process can be suppressed to 160 MPa or less.
また、自然時効硬化の程度や進行の仕方によって強度が異なる、すなわち強度やスプリングバック量がばらつく問題も解消され、押出形材の機械的性質やスプリングバック量の均一化が図れる。また、自然時効が進展した場合の押出形材の均一伸びや局部伸びの低下も解消され、この均一伸びや局部伸びが向上するとともに部材への成形性や成形精度が更に向上する。 Further, the problem that the strength varies depending on the degree of natural age hardening and the manner of progress, that is, the problem that the strength and the amount of springback vary, is solved, and the mechanical properties and the amount of springback of the extruded shape can be made uniform. In addition, the uniform elongation and local elongation of the extruded profile when natural aging progresses are also eliminated, and the uniform elongation and local elongation are improved, and the moldability and molding accuracy of the member are further improved.
（成形加工）
但し、この復元処理効果を成形加工において発現させるためには、復元処理後になるべく早く（遅滞なく）成形加工する必要がある。すなわち、７０００系アルミニウム合金押出形材素材の部材形状（製品形状）への成形加工は、復元処理後の自然時効が進まないうちに、あるいは自然時効が進んでも微小なうちに、行う必要がある。この目安としては、勿論、７０００系アルミニウム合金押出形材素材の製造条件にもよるが、これらを押しなべて決定すると、前記復元処理の急冷直後から、成形加工を開始するまでの（所要）時間を１時間（ｈｒ）以内とする。１時間を超えると、高強度な７０００系アルミニウム合金押出形材素材では、その組成からして、前記した通り自然時効が進みすぎて、成形性が著しく低下し、復元処理する意義が失われる。
(Molding)
However, in order to exhibit this restoration processing effect in the molding process, it is necessary to perform the molding process as soon as possible (without delay) after the restoration process. That is, the forming process of the 7000 series aluminum alloy extruded shape material into the member shape (product shape) needs to be performed before the natural aging after the restoration process has progressed, or while the natural aging has progressed and is still minute. . As a guideline, of course, it depends on the manufacturing conditions of the extruded material of the 7000 series aluminum alloy. However, if these are determined by pushing them, the (required) time from immediately after the rapid cooling of the restoration process to the start of the forming process is 1 Within time (hr). If it exceeds 1 hour, the high-strength 7000 series aluminum alloy extruded shape material has a natural aging that is excessively advanced as described above due to its composition, the formability is remarkably reduced, and the significance of the restoration treatment is lost.
７０００系アルミニウム合金押出形材素材の自然時効（強度増加）は短時間で進み、言い換えると、自然時効の初期の段階で、時効程度（強度増加）が大きく進む。このため、前記復元処理によって、たとえ前記復元処理条件内で行い、押出形材素材の０．２％耐力を１２０ＭＰａ以下としていても、前記復元処理の急冷直後から成形加工開始までの時間が１時間を超過した場合、自然時効が進みすぎる。この結果、勿論、成形加工の時間にもよるが、本発明の復元処理の効果が前記成形加工において充分に発現されない。 The natural aging (strength increase) of the extruded material of 7000 series aluminum alloy proceeds in a short time, in other words, the degree of aging (strength increase) greatly proceeds at the initial stage of natural aging. For this reason, even if the restoration process is performed within the restoration process conditions and the 0.2% proof stress of the extruded shape material is 120 MPa or less, the time from immediately after the restoration process is rapidly cooled to the start of the molding process is 1 hour. If this is exceeded, natural aging will progress too much. As a result, of course, the effect of the restoration process of the present invention is not sufficiently exhibited in the molding process, although it depends on the molding process time.
成形加工自体は、７０００系アルミニウム合金押出形材の、形材長手方向全体に亘る、あるいは部分的な曲げ加工、形材断面の部分的な潰し加工、形材への打抜き加工、などから選択される。これらは、残留応力の発生を伴う、塑性加工としての、部材形状への成形加工であり、これらの成形加工が単独あるいは組み合わせて、適宜選択される。 The forming process itself is selected from 7000 series aluminum alloy extruded profile, which is the entire longitudinal direction of the profile, or a partial bending process, a partial crushing process of the profile section, and a punching process to the profile. The These are forming processes into a member shape as plastic working accompanied by generation of residual stress, and these forming processes are selected as appropriate, alone or in combination.
（調質）
本発明では、前記成形加工後の部材（７０００系アルミニウム合金押出形材製部材）に人工時効処理を行い、強度を高める。本発明では、前記した押出直後（押出機の出側で）の押出工程上で連続してオンラインにて行われる急冷あるいは焼入れ処理が行われている場合は、この成形加工後で人工時効処理前の、再加熱による溶体化および焼入れ処理は行わない。
(refining)
In the present invention, an artificial aging treatment is performed on the molded member (7000-type aluminum alloy extruded profile member) to increase the strength. In the present invention, when quenching or quenching is performed on-line continuously on the extrusion process immediately after extrusion (on the exit side of the extruder), after the molding process and before artificial aging treatment The solution heat treatment and quenching by reheating are not performed.
人工時効硬化処理は、部材の機械的特性を向上させるために、好ましくは、加熱による１００〜２００℃での人工時効処理を、好ましくは１２〜３６時間（ｈｒ）行う。このような人工時効処理によって、製品の０．２％耐力３００ＭＰａ以上が確保される。 In order to improve the mechanical properties of the member, the artificial age hardening treatment is preferably performed by heating at 100 to 200 ° C., preferably for 12 to 36 hours (hr). Such an artificial aging treatment ensures a 0.2% proof stress of 300 MPa or more for the product.
以上説明した、好ましい７０００系アルミニウム合金組成および製造方法によって、押出形材が残留応力の発生を伴う成形加工によって部材化されるとともに、この成形加工の後に人工時効処理が施された７０００系アルミニウム合金部材であって、０．２％耐力が３００ＭＰａ以上であるとともに、前記成形加工を受けた部材位置における残留応力が１６０ＭＰａ以下である、高強度７０００系アルミニウム合金部材を得ることができる。 According to the preferred 7000 series aluminum alloy composition and manufacturing method described above, the extruded profile is formed into a member by a forming process accompanied by the generation of residual stress, and an artificial aging treatment is performed after the forming process. A high-strength 7000 series aluminum alloy member that is a member and has a 0.2% proof stress of 300 MPa or more and a residual stress of 160 MPa or less at the position of the member subjected to the forming process 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い。例えば、素材として、押出形材だけでなく、前記各条件や下記実施例条件を、押出から圧延に置き換えれば、圧延板材へ適用することも可能であり、本発明の技術的範囲に含まれる。 EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not restrict | limited by the following Example from the first. For example, if the above-mentioned conditions and the following example conditions are replaced from extrusion to rolling as well as an extruded profile, it can be applied to a rolled sheet as a material, and is included in the technical scope of the present invention.
次に、本発明の実施例を説明する。表１に示す各７０００系アルミニウム合金からなる中空押出形材（素材）を熱間押出し、この中空押出形材を、押出終了後に、自然時効以外は人工的に調質することなく、表２に示す種々の条件で復元処理を行った。そして、この復元処理の終了後（室温までの急冷終了後）から表２に示す種々の時間経過後に、この復元処理以外は人工的に調質することなく、残留応力の発生を伴う成形加工として、共通の条件で、曲げ加工を行って部材化した。そして、この曲げ加工後の部材に対して、共通の条件で、溶体化および焼入れ処理することなく、人工時効処理のみの調質を行い、この調質後の部材の０．２％耐力などの機械的な性質と、前記曲げ加工を受けた部材位置における残留応力、などを各々測定、評価した。これらの結果を表３に示す。 Next, examples of the present invention will be described. A hollow extruded shape (raw material) made of each 7000 series aluminum alloy shown in Table 1 is hot-extruded, and this hollow extruded shape is subjected to Table 2 without any artificial tempering other than natural aging after the end of extrusion. Restoration processing was performed under various conditions shown. And after completion | finish of this decompression | restoration process (after completion | finish of rapid cooling to room temperature), after various time passages shown in Table 2, as a shaping | molding process with generation | occurrence | production of a residual stress, without artificially refining except this restoration | repair process. The material was made into a member by bending under common conditions. Then, the material after bending is subjected to tempering only by artificial aging treatment without solution treatment and quenching treatment under common conditions, such as 0.2% proof stress of the tempered member. The mechanical properties and the residual stress at the position of the member subjected to the bending process were measured and evaluated. These results are shown in Table 3.
具体的な製造条件として、先ず、表１に示す各７０００系アルミニウム合金からなるビレット（丸棒鋳塊）に鋳造後した。このビレットを、各例とも同じく、５００℃×１０時間の均質化熱処理し、ついで押出開始温度４４０℃、押出機の出側にて、温度５００℃から水冷（急冷）する直接熱間押出し、共通して、部材としてドアビームを意図した略矩形の口形断面からなる中空押出形材（長尺材）を得た。 As specific manufacturing conditions, first, billets (round bar ingots) made of 7000 series aluminum alloys shown in Table 1 were cast. The billet is subjected to a homogenization heat treatment at 500 ° C. for 10 hours in the same manner as in each example, followed by direct hot extrusion that is water-cooled (rapidly cooled) from a temperature of 500 ° C. at the extrusion start temperature of 440 ° C. Thus, a hollow extruded shape (long material) having a substantially rectangular mouth-shaped cross section intended for a door beam as a member was obtained.
この中空押出形材の大きさは、ドアビーム例として、矩形断面を構成する、曲げ外側となるフランジの幅を比較的短い４０．０ｍｍ、曲げ内側となるフランジの幅を比較的長い５０．０ｍｍとし、互いに平行なこれらフランジの互いの外側同士の距離（形材の縦幅）を３０．０ｍｍとした。これら内外フランジ同士を直角につなぐ、互いに平行な左右のリブの互いの外側同士の距離（形材の横幅）は２５．０ｍｍとした。そして、前記曲げ外側となるフランジの左右に、前記各左右のリブの外側からの長さ（幅）が各々５．００ｍｍ、前記曲げ内側となるフランジの左右にも、前記各左右のリブの外側からの長さ（幅）が各々１０．００ｍｍづつ、左右に各フランジが張り出すような位置に、これら左右のリブを立設した。したがって、中空押出形材（ドアビーム）の断面は略パイの字型をしている。また、前記曲げ外側となるフランジの厚みは各々均一な４．０ｍｍ、前記曲げ内側となるフランジの厚みは各々均一な４．５ｍｍ、左右のリブの厚みは各々均一な２．３ｍｍであった。 As an example of a door beam, the hollow extruded shape has a rectangular cross section, the width of the flange on the outside of the bend is relatively short 40.0 mm, and the width of the flange on the inside of the bend is 50.0 mm, which is relatively long. The distance between the outer sides of these flanges parallel to each other (vertical width of the profile) was 30.0 mm. The distance between the outer sides of the right and left ribs that connect the inner and outer flanges at right angles to each other (the width of the profile) was 25.0 mm. The length (width) from the outside of each of the left and right ribs is 5.00 mm on the left and right sides of the flange that is the outer side of the bend, and the outer sides of the left and right ribs are also on the left and right sides of the flange that is the inner side of the bend. The left and right ribs were erected at positions where the flanges protruded from the left and right, each having a length (width) of 10.00 mm. Therefore, the cross section of the hollow extruded shape (door beam) is substantially pie-shaped. Further, the thicknesses of the flanges on the outside of the bends were each uniform 4.0 mm, the thicknesses of the flanges on the inside of the bends were each 4.5 mm, and the thicknesses of the left and right ribs were each 2.3 mm.
前記熱間押出後、共通して、適当な長さに切断後、２０日間の自然時効（室温時効）後に（この自然時効以外は人工的に調質することなく）、共通して硝石炉を用いて、表２に示す種々の加熱、保持温度（実体温度）、保持時間、冷却条件で、前記復元処理を行った。 After the hot extrusion, in common, after cutting to an appropriate length, after 20 days natural aging (room temperature aging) (without artificial tempering other than this natural aging) The restoration process was performed using various heating, holding temperature (substance temperature), holding time, and cooling conditions shown in Table 2.
この復元処理における急熱時の加熱速度の制御は、硝石炉のヒーターによって行い、所定実体温度に保持後、この保持時間を押出形材素材の炉からの取り出しタイミングで制御した。そして、１８〜２０℃程度の室温の温度へ、この取り出し直後から押出形材素材への水冷の程度で冷却速度を制御した。なお、押出形材素材の実体温度は、市販の接触式温度計を直接押出形材素材に接触させて計ったが、工業的には非接触の放射温度計などによって計っても良い。 The heating speed during rapid heating in the restoration process was controlled by a heater of a glass stone furnace, and after holding at a predetermined actual temperature, the holding time was controlled by the timing of taking out the extruded shape material from the furnace. And the cooling rate was controlled to the temperature of room temperature of about 18-20 degreeC by the grade of the water cooling to an extruded shape raw material immediately after this taking out. The actual temperature of the extruded shape material is measured by bringing a commercially available contact thermometer directly into contact with the extruded shape material, but may be measured industrially by a non-contact radiation thermometer or the like.
この際に、押出形材素材の０．２％耐力の経時変化として、前記熱間押出にて製造（急冷）直後と、２０日間の自然時効後でこの復元処理直前と、この復元処理における急冷後との、押出形材素材の０．２％耐力とを、各々後述する引張試験要領により測定した。 At this time, as a change with time of 0.2% proof stress of the extruded shape material, immediately after production (rapid cooling) by the hot extrusion, immediately after the natural aging for 20 days, immediately before the restoration process, and quenching in the restoration process The 0.2% proof stress of the extruded profile material was measured after the tensile test procedure described later.
また、復元処理直前の押出形材素材（Ｔ１材＝自然時効材）の導電率と、この復元処理における急冷直後の前記押出形材素材の導電率を、市販のデジタル導電率計（渦電流：電磁誘導、 試験周波数60KHz 、500KHz(標準プローブ使用時) 、測定範囲 0.8〜110 %IACS、0.45〜64MS／m 分解能）にて、測定した。測定結果は任意の５箇所の平均値とした。そして、この復元処理における急冷直後の前記押出形材素材の導電率（平均値）と、前記復元処理直前の前記押出形材素材（Ｔ１材）の導電率（平均値）との差を、Ｔ１材との導電率差として求めた。これらの結果を表２に示す。 Further, the conductivity of the extruded shape material (T1 material = natural aging material) immediately before the restoration process and the conductivity of the extruded shape material immediately after the rapid cooling in the restoration process are measured using a commercially available digital conductivity meter (eddy current: Measurement was performed at electromagnetic induction, test frequencies 60 KHz, 500 KHz (when using a standard probe), measurement range 0.8 to 110% IACS, 0.45 to 64 MS / m resolution). The measurement result was an average value at five arbitrary locations. Then, the difference between the conductivity (average value) of the extruded shape material immediately after the rapid cooling in the restoration process and the conductivity (average value) of the extruded shape material (T1 material) immediately before the restoration process is expressed as T1. It calculated | required as a conductivity difference with material. These results are shown in Table 2.
この復元処理後に、表２に示す通り、前記室温までの急冷終了直後から成形加工の開始までの時間（所要時間）を種々変えて、この復元処理以外は人工的に調質することなく、残留応力の発生や塑性加工を伴う成形加工として、曲げ加工、断面の潰し加工、打抜き加工を各々選択して行った。これらは、押出形材素材をドアビームの部材化する際の成形加工として、各々組み合わせてあるいは単独で必要になる可能性がある。 After this restoration process, as shown in Table 2, the time (required time) from immediately after completion of the rapid cooling to the room temperature to the start of the molding process was changed variously, and the rest of the process was not artificially tempered except for the restoration process. Bending, cross-sectional crushing, and punching were each selected as the forming process involving generation of stress and plastic working. These may be necessary in combination or independently as a forming process when forming the extruded shape material into a door beam member.
曲げ加工は、半径１５０ｍｍの３点曲げ試験用金型を用い、長さ１０５５ｍｍの押出形材素材を、８００ｍｍの間隔をあけた２個のローラ台（φ３０ｍｍ）上に、前記曲げ外側フランジ側が上側となるように、また左右が均等な長さとなるように載置した。そして、上側となる前記曲げ外側フランジの中心位置に、その上方側から下方に向かって、前記３点曲げ試験用金型を５００ｍｍ押し込み、部材がその長手方向に円弧状に曲がる永久変形を与えた。 Bending is performed using a three-point bending test die with a radius of 150 mm, and an extruded shape material with a length of 1055 mm is placed on two roller stands (φ30 mm) spaced 800 mm apart, and the bending outer flange side is on the upper side. It was placed so that the left and right sides would be of equal length. Then, the three-point bending test die was pushed by 500 mm toward the center of the bent outer flange on the upper side from the upper side to the lower side, and the member was given a permanent deformation that bent in an arc shape in the longitudinal direction. .
断面の潰し加工は、潰し加工前に、押出形材の端部から中空空間内に、心金を潰し加工する部分の位置に設置し、この心金を設置した押出形材の部分を前記曲げ内側フランジの下方側からダイスにより拘束し、前記心金に相対向して前記曲げ外側フランジの上方側に半径１５０ｍｍのパンチを配置し、これらの工具によって、断面の１／３の高さ（これらフランジの１／３の距離：１０．３ｍｍまで、部分的な潰し加工（プレス成形）を行った。 Before crushing, the crushing of the cross-section is placed in the hollow space from the end of the extruded profile at the position where the mandrel is to be crushed, and the part of the extruded profile where the mandrel is installed is bent. Restrained by a die from the lower side of the inner flange, a punch having a radius of 150 mm is disposed on the upper side of the bent outer flange so as to face the mandrel. Partial crushing (press molding) was performed up to a distance of 1/3 of the flange: 10.3 mm.
打抜き加工は、押出形材の前記曲げ外側フランジの上方側から、直径１０ｍｍの孔をパンチにより打ち抜いた。 In the punching process, a hole having a diameter of 10 mm was punched out from above the bent outer flange of the extruded profile.
そして、各押出形材素材のこれらの各成形性を評価した。評価は５個の各同一素材を同一条件で成形し、５個（５回）とも各成形加工時に割れや変形などの成形不良が全く生じなかった例を○、１個（１回）でも成形加工時に割れや変形などの成形不良が生じたものを×、と評した。この結果を表３に示す。 And each of these moldability of each extruded shape material was evaluated. The evaluation is an example in which 5 pieces of the same material are molded under the same conditions, and 5 pieces (5 times) have no molding defects such as cracks and deformations at the time of each forming process. The case in which molding defects such as cracks and deformation occurred during processing was evaluated as x. The results are shown in Table 3.
また、上記各押出形材素材の各成形例でのスプリングバック性を評価した。評価は上記成形例５個（５回）のうち、設定形状からのズレ幅の大きさで評価した。１個（１回）でもスプリングバックによる設定寸法や形状からのズレが大きく、修正加工を要すると判断されるものを×、全て設定寸法や形状の範囲内であり、修正加工が不要と判断される例を○と評価した。この結果を表３に示す。 Moreover, the spring back property in each molding example of each of the extruded shape materials was evaluated. Evaluation was performed by the size of the deviation width from the set shape among the above five molding examples (5 times). Even if one piece (one time), the deviation from the set dimensions and shape due to the spring back is large, and those that are judged to require correction processing are ×, all are within the set dimensions and shape range, and it is determined that correction processing is unnecessary. Examples were evaluated as ○. The results are shown in Table 3.
これらの各成形加工部材に対して、各例とも共通して、１３０℃×１２時間の人工時効処理する調質を行った。表２ではこの調質を行った例に○を付している。そして、この調質後の部材の０．２％耐力、部材の前記３点曲げ試験用金型押し込み位置（中央部）における残留応力を測定した。 Each of these molded members was tempered by an artificial aging treatment at 130 ° C. for 12 hours in common with each example. In Table 2, an example of performing this tempering is marked with a circle. Then, the 0.2% proof stress of the tempered member and the residual stress at the position where the three-point bending test die was pressed (center portion) were measured.
引張特性：
前記部材の押出方向に任意の位置から採取したＪＩＳ４号引張試験片を用い、ＪＩＳＺ２２４１に規定する金属材料試験方法に準じ、引張強さ、耐力、及び伸びを測定した。なお、これらの測定値は、各例とも３つの採取試験片の測定値の平均値とした。この結果を表３に示す。
Tensile properties:
Tensile strength, proof stress, and elongation were measured using a JIS No. 4 tensile test specimen taken from an arbitrary position in the extrusion direction of the member in accordance with a metal material test method defined in JISZ2241. In addition, these measured values were made into the average value of the measured value of three collection test pieces in each example. The results are shown in Table 3.
残留応力：
残留応力の測定法は切断法により次の手順で行った。前記部材の前記各加工位置（曲げ加工は金型押し込み中央位置、断面の潰し加工は潰し加工中央位置、打抜き加工は孔周縁位置）を測定対象位置とした。そして、これら測定対象位置表面をサンドペーパーで研磨後、アセトン洗浄し、この研磨部位に歪みゲージ２を瞬間接着剤で接着し、２４時間室温放置後、歪みゲージ２のリード線３を歪み計に接続してゼロ点設定をし、歪みゲージ２の周囲を金属のこぎりで１０ｍｍ角、深さ２ｍｍに切断して応力開放し、切断後の歪み量εを計測し、次式にて残留応力値σを算出した。 σ＝−Ｅ×ε（Ｅ；ヤング率）、ここでＥ＝６８８９４Ｎ／ｍｍ２ とした。
Residual stress:
The residual stress was measured by the following procedure using a cutting method. The respective processing positions of the member (bending processing is a mold pressing center position, cross section crushing processing is a crushing processing center position, and punching processing is a hole peripheral position) are set as measurement target positions. Then, the surface of the measurement target position is polished with sandpaper, washed with acetone, the strain gauge 2 is adhered to the polished portion with an instantaneous adhesive, and left at room temperature for 24 hours, and then the lead wire 3 of the strain gauge 2 is used as a strain gauge. Connect and set the zero point, cut the area around the strain gauge 2 with a metal saw to 10 mm square and 2 mm depth to release the stress, measure the strain amount ε after cutting, and determine the residual stress value σ by the following formula Was calculated. σ = −E × ε (E; Young's modulus), where E = 68894 N / mm 2 .
表１の合金番号１〜４の各発明例のアルミニウム合金は本発明成分組成範囲内である。これらを用いた、表２の各発明例の押出形材は、復元処理を前記した好ましい条件範囲内で行い、前記復元処理における急冷直後の０．２％耐力を１２０ＭＰａ以下に低下させているとともに、この復元処理前後（復元処理直前と急冷直後の）前記押出形材の前記導電率差を５％ＩＡＣＳ未満としている。
この結果、各発明例は表３に示すとおり、前記復元処理の諸効果を確実に発揮させることができている。すなわち、調質後の部材の０．２％耐力が最低でも３００ＭＰａ以上、より高い例では３５０ＭＰａ以上あるいは４００ＭＰａ以上である。同時に、前記成形加工を受けた部材位置における残留応力も、高いものでも１６０ＭＰａ以下、より低い例では１２０ＭＰａ以下である。
The aluminum alloy of each invention example of the alloy numbers 1-4 of Table 1 is in this invention component composition range. The extruded shapes of each invention example in Table 2 using these were subjected to the restoration process within the above-described preferable condition range, and the 0.2% proof stress immediately after the quenching in the restoration process was reduced to 120 MPa or less. The conductivity difference between the extruded shapes before and after the restoration process (immediately before the restoration process and immediately after the rapid cooling) is less than 5% IACS.
As a result, as shown in Table 3, each invention example can surely exhibit the various effects of the restoration process. That is, the 0.2% proof stress of the tempered member is at least 300 MPa, and in a higher example, it is 350 MPa or more or 400 MPa or more. At the same time, the residual stress at the position of the member that has undergone the forming process is 160 MPa or less, and 120 MPa or less in the lower example even if it is high.
これによって、本発明の復元処理によれば、２０日の自然時効（室温時効）後の高強度の７０００系アルミニウム合金押出形材であっても、また、残留応力の発生を伴う成形加工によって部材化された高強度７０００系アルミニウム合金部材であっても、人工時効処理後の部材の０．２％耐力を３００ＭＰａ以上と高強度化できるとともに、溶体化処理せずとも、前記成形加工を受けた部材位置における残留応力を１６０ＭＰａ以下に抑制できることが分かる。 As a result, according to the restoration process of the present invention, even a high-strength 7000 series aluminum alloy extruded shape after 20 days of natural aging (room temperature aging), it is also possible to form a member by forming with residual stress. Even when the high-strength 7000 series aluminum alloy member is made, the 0.2% proof stress of the member after the artificial aging treatment can be increased to 300 MPa or more, and it has undergone the above-described forming process without solution treatment. It can be seen that the residual stress at the member position can be suppressed to 160 MPa or less.
更に、各発明例は表３に示すとおり、自然時効が進展した場合の押出形材であっても、スプリングバック量が低減される結果、部材への成形性や成形精度を更に向上できることが分かる。 Furthermore, as shown in Table 3, each invention example is an extruded shape when natural aging has progressed. As a result, the amount of springback is reduced, and as a result, the moldability and molding accuracy of the member can be further improved. .
これに対して、表１の合金番号５、６、７の、各比較例のアルミニウム合金は、Ｚｎ、Ｍｇ、Ｃｕが各々少なすぎる。このため、これらの合金を用いた、表２の比較例７、８、９のように、発明例と同じ条件で製造された部材であっても、人工時効処理後の部材の０．２％耐力が３００ＭＰａ未満で不足している。 On the other hand, the aluminum alloy of each comparative example of alloy numbers 5, 6, and 7 in Table 1 has too little Zn, Mg, and Cu, respectively. For this reason, even if it is a member manufactured on the same conditions as an invention example like Comparative Examples 7, 8, and 9 of Table 2 using these alloys, 0.2% of members after artificial aging treatment Yield is less than 300 MPa.
また、表２の比較例１０〜２２は、表１の合金番号１、２、３の発明例アルミニウム合金だが、特に復元処理のいずれかの条件が好ましい範囲から外れている。このため、前記復元処理における急冷直後の０．２％耐力を１２０ＭＰａ以下に低下させていないか、この復元処理におけるこの復元処理前後（復元処理直前と急冷直後の）前記押出形材の前記導電率差が５％ＩＡＣＳ以上となっている。 Further, Comparative Examples 10 to 22 in Table 2 are invention example aluminum alloys of Alloy Nos. 1, 2, and 3 in Table 1, but any condition of the restoration treatment is out of the preferable range. Therefore, the 0.2% proof stress immediately after the rapid cooling in the restoration process is not reduced to 120 MPa or less, or the conductivity of the extruded shape before and after the restoration process (immediately before the restoration process and immediately after the quenching) in the restoration process. The difference is 5% IACS or more.
比較例１１、１５、１９、２２は、表２に示す通り、復元処理におけるこの復元処理前後（復元処理直前と急冷直後の）前記押出形材の前記導電率差が５％ＩＡＣＳ未満だが、前記復元処理における急冷直後の０．２％耐力が１２０ＭＰａを超えている。この結果、表３に示す通り、比較例１１、１５、１９、２２は人工時効処理後の部材の０．２％耐力が３００ＭＰａ以上であっても、前記成形加工を受けた部材位置における残留応力が１６０ＭＰａを超えている。また、これら各比較例は、表３に示すとおり、自然時効が進展した場合の押出形材のスプリングバック量の低減が図かれていない。このうち、比較例１１、１５、２２では、復元処理後に部材を成形するまでの時間が１時間（ｈｒ）を超えてかかりすぎていることも、その一因となっている。 In Comparative Examples 11, 15, 19, and 22, as shown in Table 2, the conductivity difference of the extruded profile before and after the restoration process in the restoration process (immediately before the restoration process and immediately after the rapid cooling) is less than 5% IACS. The 0.2% yield strength immediately after the rapid cooling in the restoration process exceeds 120 MPa. As a result, as shown in Table 3, in Comparative Examples 11, 15, 19, and 22, even if the 0.2% proof stress of the member after the artificial aging treatment is 300 MPa or more, the residual stress at the member position subjected to the molding process Exceeds 160 MPa. In each of these comparative examples, as shown in Table 3, the amount of spring back of the extruded shape when the natural aging has progressed is not reduced. Among these, in Comparative Examples 11, 15, and 22, it takes one hour (hr) to take too long until the member is molded after the restoration process.
その他の比較例は、表２に示す通り、前記復元処理における急冷直後の０．２％耐力が１２０ＭＰａ以下だが、復元処理前後（復元処理直前と急冷直後の）前記押出形材の前記導電率差が５％ＩＡＣＳを超えている。この結果、表３に示す通り、前記成形加工を受けた部材位置における残留応力が１６０ＭＰａ以下と低いものの、人工時効処理後の部材の０．２％耐力が３００ＭＰａ未満の低いレベルでしかなく、復元処理によって完全なＯ材となっていることが分かる。 In other comparative examples, as shown in Table 2, the 0.2% proof stress immediately after the rapid cooling in the restoration process is 120 MPa or less, but the conductivity difference between the extruded shapes before and after the restoration process (just before the restoration process and immediately after the quenching). Is over 5% IACS. As a result, as shown in Table 3, although the residual stress at the member position subjected to the molding process is as low as 160 MPa or less, the 0.2% proof stress of the member after the artificial aging treatment is only at a low level of less than 300 MPa, and the restoration is performed. It turns out that it has become perfect O material by processing.
以上の実施例から、前記復元処理における急冷直後の０．２％耐力を１２０ＭＰａ以下に低下させることと、この復元処理前後での前記導電率差を５％ＩＡＣＳ未満とすること、また、これらをともに満足することの意義が裏付けられる。そして、本発明における復元処理の各規定条件の、自然時効した後でも７０００系アルミニウム合金押出形材素材の、部材への成形性自体を向上させ、この成形加工によって付加される残留応力を小さくでき、更に調質処理を施して高強度化できる、技術的な意義が裏付けられる。 From the above examples, the 0.2% yield strength immediately after the rapid cooling in the restoration process is reduced to 120 MPa or less, the conductivity difference before and after the restoration process is less than 5% IACS, and these The significance of satisfying both is supported. Further, even after natural aging of each specified condition of the restoration process in the present invention, the formability of the 7000 series aluminum alloy extruded shape material itself to the member can be improved, and the residual stress applied by this forming process can be reduced. Further, the technical significance that can be further strengthened by tempering is supported.
本発明によれば、自然時効した後でも、成形性自体を向上させて、この成形加工によって付加される残留応力を小さくでき、更に調質処理を施して高強度化できる、高強度７０００系アルミニウム合金部材の製造方法および高強度７０００系アルミニウム合金部材を提供できる。このため、本発明は、軽量化された高強度７０００系アルミニウム合金からなるバンパリィンホース、ドアビームなどの自動車用補強部材あるいは航空機用などの構造部材、好適に用いることができる。 According to the present invention, a high-strength 7000 series aluminum that can improve the formability itself even after natural aging, reduce the residual stress applied by this forming process, and further increase the strength by applying a tempering treatment. An alloy member manufacturing method and a high-strength 7000 series aluminum alloy member can be provided. For this reason, the present invention can be suitably used for a bumper hose made of a lightweight high-strength 7000 series aluminum alloy, a reinforcing member for an automobile such as a door beam, or a structural member for an aircraft.
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| JP5968284B2 (en) | 2013-09-09 | 2016-08-10 | 株式会社神戸製鋼所 | Bumper structure and bumper beam manufacturing method |
| JP5968285B2 (en) * | 2013-09-09 | 2016-08-10 | 株式会社神戸製鋼所 | Bumper reinforcement and manufacturing method thereof |
| KR101571665B1 (en) | 2013-11-19 | 2015-11-25 | 현대자동차주식회사 | Aluminum alloy composition for die casting and method for heat treatment of manufacturing aluminum alloy using thereof |
| JP2016151045A (en) * | 2015-02-17 | 2016-08-22 | 株式会社神戸製鋼所 | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance |
| JP6769723B2 (en) * | 2016-03-31 | 2020-10-14 | 株式会社神戸製鋼所 | Extruded member |
| JP6677584B2 (en) * | 2016-06-17 | 2020-04-08 | 株式会社神戸製鋼所 | Method of manufacturing energy absorbing member |
| JP6611287B2 (en) * | 2018-08-27 | 2019-11-27 | 株式会社神戸製鋼所 | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance |
| JP7479854B2 (en) | 2019-02-22 | 2024-05-09 | アイシン軽金属株式会社 | Manufacturing method of aluminum alloy extrusion material |
| JP6672503B1 (en) * | 2019-03-28 | 2020-03-25 | 株式会社神戸製鋼所 | Automotive door beams made of extruded aluminum alloy |
| JP7316951B2 (en) * | 2020-01-20 | 2023-07-28 | 株式会社神戸製鋼所 | Method for manufacturing aluminum alloy member |
| CN112921255A (en) * | 2021-01-15 | 2021-06-08 | 烟台南山学院 | Method for reducing quenching residual stress of 7000 series aluminum alloy thick plate and aluminum alloy plate |
| CN113430433A (en) * | 2021-08-25 | 2021-09-24 | 中国航发北京航空材料研究院 | Aging treatment method of aluminum alloy component |
| CN114472860A (en) * | 2021-12-30 | 2022-05-13 | 深圳市中金岭南有色金属股份有限公司韶关冶炼厂 | Gradient cooling method for improving quality of zinc-aluminum-magnesium alloy |
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