JP6611287B2 - Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance - Google Patents
Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance Download PDFInfo
- Publication number
- JP6611287B2 JP6611287B2 JP2018157930A JP2018157930A JP6611287B2 JP 6611287 B2 JP6611287 B2 JP 6611287B2 JP 2018157930 A JP2018157930 A JP 2018157930A JP 2018157930 A JP2018157930 A JP 2018157930A JP 6611287 B2 JP6611287 B2 JP 6611287B2
- Authority
- JP
- Japan
- Prior art keywords
- mass
- aluminum alloy
- series aluminum
- region
- less
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Extrusion Of Metal (AREA)
Description
本発明は、高強度の７０００系アルミニウム合金押出形材の長手方向に沿った少なくとも一部の領域に、潰し加工等の塑性加工を施して部材化する７０００系アルミニウム合金部材の製造方法に関し、特に耐応力腐食割れ性に優れた７０００系アルミニウム合金部材の製造方法に関する。 The present invention relates to a method for producing a 7000 series aluminum alloy member that is formed into a member by applying plastic working such as crushing to at least a partial region along the longitudinal direction of a high-strength 7000 series aluminum alloy extruded shape. The present invention relates to a method for producing a 7000 series aluminum alloy member excellent in stress corrosion cracking resistance.
特許文献１には、プレス焼き入れで製造された７０００系アルミニウム合金押出形材の長手方向に沿った少なくとも一部の領域に、潰し加工を施して部材化する７０００系アルミニウム合金部材の製造方法が記載されている。この製造方法によれば、潰し加工の前に、前記領域に対し所定の復元処理を施し、前記復元処理後７２時間以内に潰し加工を施した後、部材全体に時効処理を施す。前記復元処理は、０．４℃／秒以上の昇温速度で加熱し、２００〜５５０℃の温度範囲に０秒を超えて保持し、次いで０．５℃／秒以上の冷却速度で冷却する、という条件で行われる。 Patent Document 1 discloses a method for producing a 7000 series aluminum alloy member that is crushed into at least a partial region along the longitudinal direction of a 7000 series aluminum alloy extruded profile produced by press hardening. Has been described. According to this manufacturing method, a predetermined restoration process is performed on the region before the crushing process, and after the crushing process is performed within 72 hours after the restoration process, the entire member is subjected to an aging process. In the restoration process, heating is performed at a temperature rising rate of 0.4 ° C./second or more, maintained in a temperature range of 200 to 550 ° C. for more than 0 seconds, and then cooled at a cooling rate of 0.5 ° C./second or more. It is performed on the condition of.
特許文献１によれば、潰し加工前に７０００系アルミニウム合金押出形材に、上記復元処理を施すことにより、プレス焼き入れ後の自然時効で析出していた金属間化合物が再固溶し、アルミニウム合金押出形材が軟化し、成形性（潰し加工性）が向上する。その結果、上記復元処理後、７０００系アルミニウム合金押出形材に潰し加工を施したとき、曲げ変形したウエブの曲げ外側に亀裂が発生するのを防止できる。同時に、ウエブに発生する引張残留応力を低減することができ、７０００系アルミニウム合金部材の耐応力腐食割れ性を改善することができる。 According to Patent Document 1, by subjecting the 7000 series aluminum alloy extruded shape to the above-described restoration treatment before crushing, the intermetallic compound precipitated by natural aging after press quenching is re-dissolved, and aluminum The alloy extruded shape is softened and the formability (crushing workability) is improved. As a result, when the 7000 series aluminum alloy extruded profile is crushed after the restoration process, it is possible to prevent cracks from occurring on the outer side of the bent web. At the same time, the tensile residual stress generated in the web can be reduced, and the stress corrosion cracking resistance of the 7000 series aluminum alloy member can be improved.
特許文献１の方法によれば、潰し加工前に７０００系アルミニウム合金押出形材に所定の復元処理を施すことにより、潰し加工により発生する引張残留応力を低減し、７０００系アルミニウム合金部材の耐応力腐食割れ性を改善することができる。しかし、潰し加工後の７０００系アルミニウム合金部材には、潰し加工により発生した引張残留応力が、解放されることなく残留している。このため、特許文献１の方法は、耐応力腐食割れ性に関して、改善の余地がある。 According to the method of Patent Document 1, the tensile residual stress generated by the crushing process is reduced by applying a predetermined restoration process to the extruded 7000 series aluminum alloy before the crushing process, and the stress resistance of the 7000 series aluminum alloy member Corrosion cracking can be improved. However, the residual tensile stress generated by crushing remains in the 7000 series aluminum alloy member after crushing without being released. For this reason, the method of patent document 1 has room for improvement regarding stress corrosion cracking resistance.
従って、本発明は、７０００系アルミニウム合金押出形材に潰し加工等の塑性加工を施して部材化する場合において、７０００系アルミニウム合金部材の耐応力腐食割れ性を、さらに改善することを目的とする。 Accordingly, an object of the present invention is to further improve the stress corrosion cracking resistance of a 7000 series aluminum alloy member when the 7000 series aluminum alloy extruded profile is subjected to plastic working such as crushing to form a member. .
本発明は、Ｚｎ：３．０〜８．０質量％、Ｍｇ：０．４〜２．５質量％、Ｃｕ：０．０５〜２．０質量％、Ｔｉ：０．００５〜０．２質量％を含有し、さらに、Ｍｎ：０．０１〜０．３質量％、Ｃｒ：０．０１〜０．３質量％、Ｚｒ：０．０１〜０．３質量％の１種又は２種以上を含有し、残部Ａｌ及び不可避不純物からなる組成を有する７０００系アルミニウム合金押出形材の少なくとも一部の領域に塑性加工を施して部材化する７０００系アルミウム合金部材の製造方法において、焼き入れ後１２時間以上自然時効した（焼き入れ後１２時間以上経過した）前記アルミニウム合金押出形材の前記領域に、０．４℃／秒以上の昇温速度で加熱し、３００〜５９０℃の温度範囲に０秒を超えて保持し、次いで０．５℃／秒以上の冷却速度で冷却する復元処理を行った後、７２時間以内に前記塑性加工を施し、さらに前記領域に対し、０．４℃／秒以上の昇温速度で加熱し、３００〜５９０℃の温度範囲に０秒を超え、３００秒以下保持し、次いで２０００℃／分以下の冷却速度で冷却する熱処理を加えた後、部材全体に人工時効処理を行うことを特徴とする。 In the present invention, Zn: 3.0-8.0 mass%, Mg: 0.4-2.5 mass%, Cu: 0.05-2.0 mass%, Ti: 0.005-0.2 mass% 1% or more of Mn: 0.01 to 0.3% by mass, Cr: 0.01 to 0.3% by mass, Zr: 0.01 to 0.3% by mass 12 hours after quenching in a method for producing a 7000 series aluminum alloy member containing at least a part of a 7000 series aluminum alloy extruded profile having a composition comprising the balance Al and inevitable impurities. The aluminum alloy extruded profile that has been naturally aged (heated for 12 hours or more after quenching) is heated at a heating rate of 0.4 ° C./second or more in a temperature range of 300 to 590 ° C. for 0 second. And then cooled at a cooling rate of 0.5 ° C / second or more. After performing the restoration process, the plastic working is performed within 72 hours, and the region is further heated at a temperature rising rate of 0.4 ° C./second or more, and 0 second is applied to the temperature range of 300 to 590 ° C. It is characterized in that the whole member is subjected to artificial aging treatment after being subjected to heat treatment for exceeding 300 seconds or less and then cooling at a cooling rate of 2000 ° C./minute or less.
上記復元処理に代えて、前記アルミニウム合金押出形材を焼き入れ後、１２時間未満の間に前記領域に塑性加工を施すようにしてもよい。
なお、上記製造方法において、塑性加工には潰し加工のほか、曲げ加工、拡管加工（例えば電磁成形による拡管）、打抜き加工等、材料中に引張残留応力が発生する塑性加工が広く含まれる。
Instead of the restoration process, the region may be subjected to plastic working in less than 12 hours after quenching the aluminum alloy extruded shape.
In the above manufacturing method, plastic working widely includes plastic working in which tensile residual stress is generated in the material, such as bending, pipe expansion (for example, pipe expansion by electromagnetic forming), punching, and the like, in addition to crushing.
本発明によれば、７０００系アルミニウム合金押出形材に対し塑性加工を施して部材化する場合に、塑性加工により発生した引張残留応力を低減して、耐応力腐食割れ性がさらに改善された７０００系アルミニウム合金部材を提供することができる。 According to the present invention, when a 7000 series aluminum alloy extruded shape is subjected to plastic working to form a member, the tensile residual stress generated by the plastic working is reduced, and the stress corrosion cracking resistance is further improved. An aluminum alloy member can be provided.
以下、本発明に係る７０００系アルミニウム合金部材及びその製造方法について、具体的に説明する。
（アルミニウム合金の組成）
まず、本発明に係る７０００系アルミニウム合金の組成について説明する。ただし、この組成は特許文献１に記載された７０００系アルミニウム合金と同じである。
Ｚｎ：３．０〜８．０質量％
Ｍｇ：０．４〜２．５質量％
ＺｎとＭｇは金属間化合物であるＭｇＺｎ２を形成して、７０００系アルミニウム合金の強度を向上させる元素である。Ｚｎ含有量が３．０質量％未満又はＭｇ含有量が０．４質量％未満では、実用材として必要な２００ＭＰａ以上の耐力が得られない。一方、Ｚｎ含有量が８．０質量％を越え又はＭｇ含有量が２．５質量％を越えると、塑性加工を施したとき亀裂の発生が防止できず、同時に、塑性加工により発生する引張残留応力が大きくなり、その後の熱処理によっても耐応力腐食割れ性が改善できない。高強度化及び軽量化の観点からは、Ｚｎ含有量、Ｍｇ含有量はより高合金側、例えばそれぞれ５．０〜８．０質量％、１．０〜２．５質量％、合計で６．０〜１０．５質量％が好ましい。
Hereinafter, the 7000 series aluminum alloy member and the manufacturing method thereof according to the present invention will be specifically described.
(Aluminum alloy composition)
First, the composition of the 7000 series aluminum alloy according to the present invention will be described. However, this composition is the same as that of the 7000 series aluminum alloy described in Patent Document 1.
Zn: 3.0-8.0 mass%
Mg: 0.4 to 2.5% by mass
Zn and Mg are elements that improve the strength of the 7000 series aluminum alloy by forming MgZn 2 that is an intermetallic compound. When the Zn content is less than 3.0 mass% or the Mg content is less than 0.4 mass%, the proof stress of 200 MPa or more necessary as a practical material cannot be obtained. On the other hand, if the Zn content exceeds 8.0% by mass or the Mg content exceeds 2.5% by mass, the occurrence of cracks cannot be prevented when plastic processing is performed, and at the same time, tensile residuals generated by plastic processing The stress increases, and the stress corrosion cracking resistance cannot be improved even by the subsequent heat treatment. From the viewpoint of increasing the strength and reducing the weight, the Zn content and the Mg content are higher on the alloy side, for example, 5.0 to 8.0 mass% and 1.0 to 2.5 mass%, respectively, for a total of 6. 0-10.5 mass% is preferable.
Ｃｕ：０．０５〜２．０質量％
Ｃｕは７０００系アルミニウム合金の強度を向上させる元素である。Ｃｕ含有量が０．０５質量％未満では十分な強度向上効果がなく、一方、２．０質量％を越えると押出加工性の低下を招く。Ｃｕ含有量は、好ましくは０．５〜１．５質量％である。
Ｔｉ：０．００５〜０．２質量％
Ｔｉは７０００系アルミニウム合金の鋳造時に結晶粒を微細化して、押出形材の成形性を向上させる作用があり、０．００５質量％以上添加する。一方、０．２質量％を越えるとその作用が飽和し、かつ粗大な金属間化合物が晶出して、かえって成形性を低下させる。
Cu: 0.05-2.0 mass%
Cu is an element that improves the strength of the 7000 series aluminum alloy. When the Cu content is less than 0.05% by mass, there is no sufficient strength improvement effect, while when it exceeds 2.0% by mass, the extrusion processability is lowered. The Cu content is preferably 0.5 to 1.5 mass%.
Ti: 0.005 to 0.2% by mass
Ti has the effect of refining crystal grains during casting of a 7000 series aluminum alloy to improve the formability of the extruded profile, and is added in an amount of 0.005% by mass or more. On the other hand, when the content exceeds 0.2% by mass, the action is saturated and a coarse intermetallic compound is crystallized, which deteriorates the formability.
Ｍｎ：０．０１〜０．３質量％
Ｃｒ：０．０１〜０．３質量％
Ｚｒ：０．０１〜０．３質量％
Ｍｎ，Ｃｒ，Ｚｒは７０００系アルミニウム合金押出形材の再結晶を抑制して、結晶組織を微細再結晶又は繊維状組織とし、耐応力腐食割れ性を向上させる作用があるため、その１種又は２種以上を上記範囲内で添加する。
不可避不純物
７０００系アルミニウム合金の主要な不可避不純物として、Ｆｅ及びＳｉが挙げられる。７０００系アルミニウム合金の諸特性を低下させないため、Ｆｅ：０．３５質量％以下、Ｓｉ：０．３質量％以下に制限される。
Mn: 0.01 to 0.3% by mass
Cr: 0.01-0.3 mass%
Zr: 0.01 to 0.3% by mass
Mn, Cr, Zr has the effect of suppressing the recrystallization of the 7000 series aluminum alloy extruded shape and making the crystal structure a fine recrystallized or fibrous structure and improving the stress corrosion cracking resistance. Two or more kinds are added within the above range.
Inevitable impurities Fe and Si are the main inevitable impurities of the 7000 series aluminum alloy. In order not to deteriorate various properties of the 7000 series aluminum alloy, the content is limited to Fe: 0.35 mass% or less and Si: 0.3 mass% or less.
（アルミニウム合金部材の製造方法）
上記組成を有する７０００系アルミニウム合金押出形材をプレス焼き入れし、又は空気炉等で再加熱後焼き入れし、自然時効させた後（通常、数日〜数ヶ月の保管期間があり、その間に自然時効が進む）、同形材の長手方向に沿った全部又は一部の領域に対し、復元処理を行う。前記復元処理は、０．４℃／秒以上の昇温速度で加熱し、３００〜５９０℃の温度範囲に０秒を超えて保持し、次いで０．５℃／秒以上の冷却速度で冷却するという条件で行う。焼き入れ（プレス焼き入れ、再加熱後の焼き入れ）の冷却速度は、０．５℃／秒以上の冷却速度（ファン空冷）で行うことが望ましい。
復元処理後７２時間以内に、前記領域に塑性加工を施して前記押出形材を部材化し、さらに、前記領域に所定の熱処理（以下、後熱処理という）を施した後、部材全体に時効処理を施す。前記後熱処理は、０．４℃／秒以上の昇温速度で加熱し、３００〜５９０℃の温度範囲に０を超え、３００秒以下保持し、次いで２０００℃／分以下の冷却速度で冷却するという条件で行う。
(Method for producing aluminum alloy member)
After extruding a 7000 series aluminum alloy extruded shape having the above composition, or after reheating in an air furnace or the like and quenching and natural aging (usually a storage period of several days to several months, The natural aging advances), and the restoration process is performed on all or a part of the region along the longitudinal direction of the same shape material. In the restoration process, heating is performed at a temperature rising rate of 0.4 ° C./second or more, maintained in a temperature range of 300 to 590 ° C. for more than 0 seconds, and then cooled at a cooling rate of 0.5 ° C./second or more. This is done under the condition. The cooling rate of quenching (press quenching, quenching after reheating) is preferably performed at a cooling rate of 0.5 ° C./second or more (fan air cooling).
Within 72 hours after the restoration process, the region is subjected to plastic working to form the extruded shape member, and the region is subjected to a predetermined heat treatment (hereinafter referred to as post heat treatment), and then the entire member is subjected to an aging treatment. Apply. In the post-heat treatment, heating is performed at a temperature rising rate of 0.4 ° C./second or more, and the temperature range of 300 to 590 ° C. is over 0, maintained for 300 seconds or less, and then cooled at a cooling rate of 2000 ° C./minute or less. This is done under the condition.
焼き入れ後の押出形材は、自然時効により金属間化合物が析出し、硬化しているが、特許文献１にも記載されているとおり、塑性加工の前に前記復元処理を受けることで金属間化合物が再固溶し、押出形材は軟化し、成形性が向上する。これにより、復元処理を受けた領域に塑性加工を施したとき、前記領域に亀裂が発生するのを防止し、同時に、前記領域に発生する引張残留応力を低減することができる。復元処理の加熱手段として、例えば高周波誘導加熱装置又は硝石炉を利用することができる。
なお、７０００系アルミニウム合金押出形材は、自然時効の進行が早く、焼き入れ後１２時間程度経過すると硬化し、成形性が低下する。前記復元処理は、焼き入れ後１２時間以上自然時効した（焼き入れ後１２時間以上経過した）アルミニウム合金押出形材に対し行われる。
The extruded shape material after quenching has an intermetallic compound precipitated and hardened by natural aging, but as described in Patent Document 1, it is intermetallic by receiving the restoration treatment before plastic working. The compound is re-dissolved, the extruded shape is softened, and the moldability is improved. As a result, when plastic working is performed on the region that has undergone the restoration process, cracks can be prevented from occurring in the region, and at the same time, the tensile residual stress generated in the region can be reduced. For example, a high-frequency induction heating device or a glass stone furnace can be used as the heating means for the restoration process.
In addition, the 7000 series aluminum alloy extruded profile has a fast natural aging, and is cured after about 12 hours after quenching, resulting in a decrease in formability. The restoration treatment is performed on an aluminum alloy extruded shape that has been naturally aged for 12 hours or more after quenching (more than 12 hours have passed after quenching).
復元処理において、昇温速度が０．４℃／秒未満では、昇温過程において金属間加工物の析出が促進され、復元処理の効果が得られない。
保持温度（実体温度）が３００℃未満では、自然時効で析出した金属間化合物が再固溶せず、むしろ析出が促進されて、復元処理の効果が得られない。一方、保持温度が５９０℃を越えるとバーニングのおそれがある。
復元処理の保持時間は０秒を超えることとする。すなわち、押出形材が保持温度に到達後、同温度に所定時間保持してから冷却してもよく、直ちに冷却してもよい。保持時間の上限は特に限定的ではないが、例えば６０秒以内の短時間で済ます方が、生産効率の点で好ましく、１０秒以内、５秒以内のより短時間が好ましい。また、押出形材の一部の領域に対し復元処理を行う場合、前記領域に隣接する領域に中途半端に熱が伝達して、前記隣接する領域が軟化するのを防止する意味でも、保持時間は短時間で済ますことが好ましい。
In the restoration process, if the rate of temperature rise is less than 0.4 ° C./second, precipitation of the intermetallic workpiece is promoted during the temperature raising process, and the effect of the restoration process cannot be obtained.
When the holding temperature (substance temperature) is less than 300 ° C., the intermetallic compound precipitated by natural aging does not re-dissolve, but rather the precipitation is promoted and the effect of the restoration treatment cannot be obtained. On the other hand, if the holding temperature exceeds 590 ° C., there is a risk of burning.
It is assumed that the retention time of the restoration process exceeds 0 seconds. That is, after the extruded profile reaches the holding temperature, it may be cooled after being held at the same temperature for a predetermined time, or may be cooled immediately. The upper limit of the holding time is not particularly limited. For example, it is preferable that a short time of 60 seconds or less is preferable in terms of production efficiency, and a shorter time of 10 seconds or less and 5 seconds or less is preferable. Also, in the case of performing a restoration process on a part of the extruded profile, the holding time is also used to prevent heat from being transferred halfway to the area adjacent to the area and softening the adjacent area. It is preferable to complete in a short time.
復元処理において、保持温度からの冷却速度が０．５℃／秒未満の緩冷却では、冷却過程で再び金属間化合物の析出が生じ、この復元処理の効果が弱まり又は失われる。この冷却速度は、ファン空冷以上の冷却速度（例えば１５０℃／分以上）が好ましく、より好ましくは、水冷である。なお、従来の復元処理では、冷却過程の冷却速度について特に考慮されていなかった。
復元処理後、７２時間以内に塑性加工を行うのは、自然時効により金属間化合物が析出し、押出形材が再硬化する前に塑性加工を行う必要があるからである。
In the restoration process, when the cooling rate from the holding temperature is less than 0.5 ° C./second, the intermetallic compound is precipitated again in the cooling process, and the effect of the restoration process is weakened or lost. The cooling rate is preferably a cooling rate higher than fan air cooling (for example, 150 ° C./min or higher), and more preferably water cooling. In the conventional restoration process, the cooling rate in the cooling process is not particularly considered.
The reason why the plastic working is performed within 72 hours after the restoration process is that it is necessary to perform the plastic working before the intermetallic compound is precipitated by natural aging and the extruded shape material is re-hardened.
塑性加工後の後熱処理は、塑性加工により発生した引張残留応力を解放し、７０００系アルミニウム合金部材の耐応力腐食割れ性を改善するために行われる。この後熱処理の加熱手段として、例えば高周波誘導加熱装置又は硝石炉を利用することができる。
後熱処理の昇温速度が０．４℃／秒未満では、生産効率が低下する。部材の一部の領域に対しこの後熱処理を行う場合、前記領域に隣接する領域に中途半端に熱が伝達して、前記隣接する領域が軟化するのを防止する意味でも、昇温速度は大きい方が好ましい。
後熱処理の保持温度（実体温度）が３００℃未満では、部材の引張残留応力が十分解放されず、耐応力腐食割れ性を改善できない。一方、保持温度が５９０℃を越えるとバーニングのおそれがある。
The post heat treatment after the plastic working is performed in order to release the tensile residual stress generated by the plastic working and improve the stress corrosion cracking resistance of the 7000 series aluminum alloy member. For example, a high-frequency induction heating apparatus or a nitrite furnace can be used as the heating means for the subsequent heat treatment.
When the temperature increase rate of the post heat treatment is less than 0.4 ° C./second, the production efficiency is lowered. When heat treatment is subsequently performed on a partial region of the member, the rate of temperature increase is also high in order to prevent heat from being transferred halfway to the region adjacent to the region to soften the adjacent region. Is preferred.
If the holding temperature (substance temperature) of the post heat treatment is less than 300 ° C., the tensile residual stress of the member is not sufficiently released, and the stress corrosion cracking resistance cannot be improved. On the other hand, if the holding temperature exceeds 590 ° C., there is a risk of burning.
後熱処理の保持時間は０秒を超えるものとする。すなわち、部材が保持温度に到達後、同温度に所定時間保持してから冷却してもよく、直ちに冷却してもよい。保持時間の上限は、生産効率の観点から３００秒以内の短時間とし、さらに１０秒以内、５秒以内のより短時間が好ましい。部材の一部の領域に対し後熱処理を行う場合、前記領域に隣接する領域に中途半端に熱が伝達して、前記隣接する領域が軟化するのを防止する意味でも、保持時間は短時間で済ますことが好ましい。
後熱処理において、保持温度からの冷却速度が２０００℃／分を超える急冷では、金属間化合物の固溶量が増加する（冷却中の析出が少ない）。このため、続く人工時効処理で金属間化合物が結晶粒界に微細かつ連続的に析出し、これが腐食環境下で溶解し、部材の耐応力腐食割れ性を低下させる原因となる。保持温度からの冷却は放冷程度の緩冷却（１０℃／分）でもよいが、時効処理後に高強度を得るには、ファン空冷以上の冷却速度（例えば１５０℃／分以上）であることが好ましい。
The holding time for the post heat treatment shall exceed 0 seconds. That is, after the member reaches the holding temperature, it may be cooled after being held at the same temperature for a predetermined time or immediately. The upper limit of the holding time is a short time of 300 seconds or less from the viewpoint of production efficiency, and more preferably a short time of 10 seconds or less and 5 seconds or less. When post-heat treatment is performed on a partial region of the member, the holding time is short in order to prevent heat from being transferred halfway to the region adjacent to the region and softening of the adjacent region. It is preferable to finish.
In the post heat treatment, when the cooling rate from the holding temperature exceeds 2000 ° C./min, the amount of solid solution of the intermetallic compound increases (the precipitation during cooling is small). For this reason, the intermetallic compound precipitates finely and continuously at the grain boundary in the subsequent artificial aging treatment, which dissolves in a corrosive environment and causes the stress corrosion cracking resistance of the member to deteriorate. Cooling from the holding temperature may be slow cooling (10 ° C./min) as low as it is allowed to cool, but in order to obtain high strength after the aging treatment, the cooling rate should be higher than fan air cooling (eg, 150 ° C./min or more). preferable.
人工時効処理の条件は、特に限定的ではなく、通常の７０００系アルミニウム合金で行われている一般的な時効処理条件で行うことができる。又は、一般的な時効処理より高温・長時間の条件で時効処理（過時効処理）を行うことができる。塑性加工後の熱処理による耐応力腐食割れ性の改善効果は、その後の人工時効処理が一般的な時効処理でも過時効処理でも得られる。 The conditions for the artificial aging treatment are not particularly limited, and can be carried out under the general aging treatment conditions used for ordinary 7000 series aluminum alloys. Alternatively, the aging treatment (over-aging treatment) can be performed under conditions of higher temperature and longer time than general aging treatment. The effect of improving the stress corrosion cracking resistance by the heat treatment after the plastic working can be obtained whether the subsequent artificial aging treatment is general aging treatment or overaging treatment.
以上、本発明に係るアルミニウム合金部材の製造方法を説明したが、自然時効したアルミニウム合金押出形材に復元処理を行う代わりに、焼き入れ（プレス焼き入れ、再加熱後の焼き入れ）後のアルミニウム合金押出形材に対し、焼き入れ後１２時間未満の間に、塑性加工を施すようにしてもよい。焼き入れ後１２時間未満の間に塑性加工を行うのであれば、７０００系アルミニウム合金押出形材の自然時効が進んでおらず、復元処理後と同様に、割れの発生が防止されると共に、塑性加工により発生する引張残留応力が低減し、耐応力腐食割れ性が改善される。 As mentioned above, although the manufacturing method of the aluminum alloy member based on this invention was demonstrated, the aluminum after quenching (press quenching and quenching after reheating) instead of performing a restoration process to the naturally aged aluminum alloy extruded profile The alloy extruded profile may be subjected to plastic working in less than 12 hours after quenching. If plastic working is performed in less than 12 hours after quenching, the natural aging of the 7000 series aluminum alloy extruded shape has not progressed, and cracking is prevented and plasticity is prevented as in the case of the restoration treatment. The tensile residual stress generated by processing is reduced, and the stress corrosion cracking resistance is improved.
表１に示すＮｏ．１〜２２の組成を有する７０００系アルミニウム合金ビレットに、４７０℃×６ｈｒの均質化処理を行い、押出温度（ビレット温度）４７０℃、押出速度５ｍ／分の条件で押出成形した。押出後はファン空冷（冷却速度は約２００℃／分）でプレス焼き入れした。図１に示すように、押出形材の断面形状は高さ４５ｍｍ×幅４５ｍｍの矩形で、肉厚は全て２ｍｍである。 No. shown in Table 1. A 7000 series aluminum alloy billet having a composition of 1 to 22 was subjected to a homogenization treatment of 470 ° C. × 6 hr, and extruded under conditions of an extrusion temperature (billet temperature) of 470 ° C. and an extrusion speed of 5 m / min. After extrusion, it was press-quenched with fan air cooling (cooling rate: about 200 ° C./min). As shown in FIG. 1, the cross-sectional shape of the extruded profile is a rectangle having a height of 45 mm and a width of 45 mm, and the thickness is 2 mm.
この押出形材を長さ１０００ｍｍに切断して試験材とした。Ｎｏ．１〜１４，１７〜２２の試験材については、プレス焼き入れから９６時間後に、試験材の長手方向に沿った一部の領域（一方の端から長手方向に２００ｍｍまでの範囲）に、表２に示す条件で復元処理を行った後、プレス機を用いて同領域に冷間で潰し加工を行った。図２は潰し加工前後の様子を示すもので、１は試験材（押出形材）、２はプレス機の定盤、３は潰し加工用治具である。Ｎｏ．１５、１６については、復元処理を行うことなく、プレス焼き入れから１０時間後に、同じく冷間で潰し加工を行った。潰し加工による潰し量ｈを表２に示す。
続いて、前記領域（潰し加工を行った領域）に、表２に示す条件で後熱処理を行った（Ｎｏ．１７のみ行わず）。その後、表２に示す条件で人工時効処理を行った。
This extruded profile was cut into a length of 1000 mm to obtain a test material. No. For the test materials 1 to 14 and 17 to 22, 96 hours after press quenching, in a part of the region along the longitudinal direction of the test material (range from one end to 200 mm in the longitudinal direction), Table 2 After performing the restoration process under the conditions shown in Fig. 1, the same region was cold crushed using a press machine. FIG. 2 shows a state before and after crushing, where 1 is a test material (extruded profile), 2 is a press platen, and 3 is a crushing jig. No. For 15 and 16, the crushing process was performed in the same cold manner 10 hours after press quenching without performing the restoration process. Table 2 shows the amount h of crushing by crushing.
Subsequently, post-heat treatment was performed on the above-described region (region where crushing was performed) under the conditions shown in Table 2 (not only No. 17). Thereafter, artificial aging treatment was performed under the conditions shown in Table 2.
人工時効処理後の試験材を用いて、クロム酸法によるＳＣＣ（応力腐食割れ）試験を以下の要領で実施した。また、別途、下記要領で引張試験を実施した。その結果を表２に示す。
（ＳＣＣ試験）
３．６質量％ＣｒＯ３−３．０質量％Ｋ２Ｃｒ２Ｏ７−０．３質量％ＮａＣｌを含む試験液（水溶液）を９５〜１００℃に加熱し、試験材を１６ｈｒ浸漬し、その後、潰し加工を行った領域においてＳＣＣ発生有無を確認した。このＳＣＣ試験は、特許文献１の実施例で行われたＳＣＣ試験より、温度及び時間について厳しい条件で行っている。
（引張試験）
プレス焼き入れ後の各押出形材を所定長さに切断して試験材とし、各試験材に対し、プレス焼き入れから９６時間後に、表２に示す条件で復元処理を行い（Ｎｏ．１５、１６のみ行わず）、続いて表２に示す条件で後熱処理を行った（Ｎｏ．１７のみ行わず）。その後、各試験材に対し、表２に示す条件で人工時効処理を行った。人工時効処理後の試験材から、長手方向が押出方向となるようにＪＩＳ５号試験片を採取し、ＪＩＳ−Ｚ２２４１の引張試験法に従って、引張強さを測定した。
Using the test material after the artificial aging treatment, an SCC (stress corrosion cracking) test by the chromic acid method was performed as follows. Separately, a tensile test was performed as follows. The results are shown in Table 2.
(SCC test)
A test liquid (aqueous solution) containing 3.6 mass% CrO 3 -3.0 mass% K 2 Cr 2 O 7 -0.3 mass% NaCl is heated to 95 to 100 ° C., and the test material is immersed for 16 hours, and thereafter The presence or absence of SCC was confirmed in the area where crushing was performed. This SCC test is performed under stricter conditions regarding temperature and time than the SCC test performed in the example of Patent Document 1.
(Tensile test)
Each extruded shape after press quenching is cut into a predetermined length to obtain a test material, and each test material is subjected to a restoration process under the conditions shown in Table 2 96 hours after press quenching (No. 15, Subsequently, post-heat treatment was performed under the conditions shown in Table 2 (only No. 17 was not performed). Thereafter, each test material was subjected to artificial aging treatment under the conditions shown in Table 2. A JIS No. 5 test piece was collected from the test material after the artificial aging treatment so that the longitudinal direction was the extrusion direction, and the tensile strength was measured according to the tensile test method of JIS-Z2241.
本発明の実施例であるＮｏ．１〜１６は、塑性加工後に本発明に規定する条件で後熱処理を行ったものであり、表２に示すように、ＳＣＣが発生せず、高い強度（２００ＭＰａ以上）が得られている。
一方、本発明の比較例であるＮｏ．１７は、潰し加工後に後熱処理が行われなかった例で、ＳＣＣが発生していた。これは、潰し加工で発生した残留応力が、後熱処理で解放されなかったためと考えられる。なお、Ｎｏ．１７の製造プロセスは、特許文献１に記載された方法に倣ったものである。
Ｎｏ．１８，１９は、後熱処理の保持温度が本発明の規定を外れた例であり、いずれもＳＣＣが発生していた。いずれも後熱処理の保持温度が低く、潰し加工で発生した残留応力を解放する効果が小さかったため、ＳＣＣが発生したと考えられる。
No. which is an example of the present invention. Nos. 1 to 16 were post-heat-treated under the conditions specified in the present invention after plastic working. As shown in Table 2, no SCC was generated and high strength (200 MPa or more) was obtained.
On the other hand, No. 1 which is a comparative example of the present invention. No. 17 was an example in which post-heat treatment was not performed after crushing, and SCC occurred. This is presumably because the residual stress generated in the crushing process was not released by the post heat treatment. In addition, No. The manufacturing process 17 follows the method described in Patent Document 1.
No. Nos. 18 and 19 are examples in which the holding temperature of the post heat treatment deviated from the definition of the present invention, and SCC occurred in both cases. In any case, the holding temperature of the post-heat treatment was low and the effect of releasing the residual stress generated in the crushing process was small, so it is considered that SCC occurred.
Ｎｏ．２０は、後熱処理の冷却速度が本発明の規定を外れた例であり、ＳＣＣが発生していた。この例では、後熱処理により残留応力は一応低下していると考えられるが、冷却速度が大きいことにより、ＭｇＺｎ２の固溶量が増加し、人工時効処理後の粒界の析出状態が微細かつ連続的になってＳＣＣ感受性が高まり、ＳＣＣが発生したものと考えられる。
Ｎｏ．２１は、後熱処理の保持時間が本発明の規定を外れた例であり、Ｎｏ．２２は後熱処理の昇温速度が本発明の規定を外れた例である。Ｎｏ．２１は、後熱処理の昇温速度が小さく、保持温度に到達するまでの時間が長時間となり、Ｎｏ．２２は、保持温度での保持時間が長く、いずれも後熱処理を行った領域の近傍領域に熱が伝わって、前記近傍領域が焼鈍状態となり、強度が低下（２００ＭＰａ未満）していた。
No. No. 20 is an example in which the cooling rate of the post heat treatment deviated from the definition of the present invention, and SCC was generated. In this example, it is considered that the residual stress is temporarily reduced by the post heat treatment, but due to the high cooling rate, the solid solution amount of MgZn 2 increases, and the precipitation state of the grain boundary after the artificial aging treatment is fine and It is considered that the SCC sensitivity increased continuously and SCC was generated.
No. No. 21 is an example in which the post-heat treatment holding time deviates from the definition of the present invention. 22 is an example in which the temperature increase rate of the post heat treatment deviates from the definition of the present invention. No. No. 21 has a low rate of temperature increase in the post heat treatment, and it takes a long time to reach the holding temperature. In No. 22, the holding time at the holding temperature was long, and in all cases, heat was transmitted to the region near the post-heat-treated region, the neighboring region was in an annealed state, and the strength was reduced (less than 200 MPa).
１ 試験材（押出形材）
２ 定盤
３ 潰し加工用治具
1 Test material (extrusion profile)
2
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2018157930A JP6611287B2 (en) | 2018-08-27 | 2018-08-27 | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2018157930A JP6611287B2 (en) | 2018-08-27 | 2018-08-27 | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2015029061A Division JP2016151045A (en) | 2015-02-17 | 2015-02-17 | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2019011511A JP2019011511A (en) | 2019-01-24 |
| JP6611287B2 true JP6611287B2 (en) | 2019-11-27 |
Family
ID=65226233
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2018157930A Expired - Fee Related JP6611287B2 (en) | 2018-08-27 | 2018-08-27 | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6611287B2 (en) |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5671422B2 (en) * | 2011-07-25 | 2015-02-18 | 株式会社神戸製鋼所 | Method for producing high strength 7000 series aluminum alloy member and high strength 7000 series aluminum alloy member |
| JP6195446B2 (en) * | 2013-01-25 | 2017-09-13 | 株式会社神戸製鋼所 | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance |
| JP6195448B2 (en) * | 2013-01-30 | 2017-09-13 | 株式会社神戸製鋼所 | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance |
-
2018
- 2018-08-27 JP JP2018157930A patent/JP6611287B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2019011511A (en) | 2019-01-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2016151045A (en) | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance | |
| JP5671422B2 (en) | Method for producing high strength 7000 series aluminum alloy member and high strength 7000 series aluminum alloy member | |
| RU2413025C2 (en) | Product out of deformed aluminium alloy of aa7000 series and procedure for production of said product | |
| JP6195446B2 (en) | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance | |
| JP6193808B2 (en) | Aluminum alloy extruded material and method for producing the same | |
| JP2014145119A (en) | 7000 series aluminum alloy member excellent in stress corrosion crack resistance and its manufacturing method | |
| JPWO2017169962A1 (en) | High strength aluminum alloy extruded material with excellent corrosion resistance and good hardenability, and method for producing the same | |
| JP5968285B2 (en) | Bumper reinforcement and manufacturing method thereof | |
| KR20210046733A (en) | 7XXX-Series Aluminum Alloy Products | |
| JP6677584B2 (en) | Method of manufacturing energy absorbing member | |
| JP7018332B2 (en) | Manufacturing method of bent molded products using aluminum alloy | |
| JP2009167464A (en) | Method for producing aluminum alloy material having excellent toughness | |
| JP7479854B2 (en) | Manufacturing method of aluminum alloy extrusion material | |
| TWI434939B (en) | Aluminium alloy and process of preparation thereof | |
| KR102506754B1 (en) | High strength aluminum alloy plate parts and manufacturing method thereof | |
| US20230357902A1 (en) | Method For Manufacturing Aluminum Alloy Extruded Material With High Strength And Excellent In SCC Resistance And Hardenability | |
| JP5540546B2 (en) | Manufacturing method of high strength aluminum alloy bolt | |
| US20230357889A1 (en) | Method For Manufacturing Aluminum Alloy Extruded Material | |
| US9834833B2 (en) | Aluminum alloy material exhibiting excellent bendability and method for producing the same | |
| JP6611287B2 (en) | Method for producing 7000 series aluminum alloy member excellent in stress corrosion cracking resistance | |
| KR20180070935A (en) | Roll-forming method of high strength aluminum alloy and roll-forming molding using the same | |
| JP6005539B2 (en) | Method for producing high strength 7000 series aluminum alloy member | |
| JP4993170B2 (en) | Aluminum alloy extruded shape having excellent impact absorption characteristics and good hardenability, and method for producing the same | |
| JP2006009066A (en) | Member made of aluminum alloy having excellent ductility | |
| JPWO2016056240A1 (en) | Aluminum alloy plate for superplastic forming and manufacturing method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20180925 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20191001 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20191025 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 6611287 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| LAPS | Cancellation because of no payment of annual fees |