JP3686146B2 - Method for producing aluminum alloy sheet for forming - Google Patents
Method for producing aluminum alloy sheet for forming Download PDFInfo
- Publication number
- JP3686146B2 JP3686146B2 JP33108595A JP33108595A JP3686146B2 JP 3686146 B2 JP3686146 B2 JP 3686146B2 JP 33108595 A JP33108595 A JP 33108595A JP 33108595 A JP33108595 A JP 33108595A JP 3686146 B2 JP3686146 B2 JP 3686146B2
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- less
- alloy
- aluminum alloy
- range
- 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
Description
【０００１】
【発明の属する技術分野】
この発明は、自動車ボディシートや部品、各種機械器具、家電部品等の素材として、成形加工および塗装焼付を施して使用されるアルミニウム合金板の製造方法に関するものであり、特に成形性が良好であるとともに、塗装焼付後の強度が高く、かつ室温での経時変化が少ない成形加工用アルミニウム合金板の製造方法に関するものである。
【０００２】
【従来の技術】
自動車のボディシートには、従来は主として冷延鋼板を使用することが多かったが、最近では車体軽量化の観点から、アルミニウム合金圧延板を使用することが進められている。自動車のボディシートはプレス加工を施して使用するところから、成形加工性が優れていること、また成形加工時におけるリューダースマークが発生しないことが要求され、また高強度を有することも必須であって、特に塗装焼付を施すことから、塗装焼付後に高強度が得られることが要求される。
【０００３】
従来このような自動車用ボディシート向けのアルミニウム合金としては、時効性を有するＪＩＳ６０００番系合金、すなわちＡｌ−Ｍｇ−Ｓｉ系合金が主として使用されている。この時効性Ａｌ−Ｍｇ−Ｓｉ系合金では、塗装焼付前の成形加工時においては比較的強度が低く、成形性が優れており、一方塗装焼付時の加熱によって時効されて塗装焼付後の強度が高くなる利点を有するほか、リューダースマークが発生しない等の利点を有する。
【０００４】
ところで塗装焼付時における時効硬化を期待したＡｌ−Ｍｇ−Ｓｉ系合金板の製造方法としては、鋳塊を均質化熱処理した後、熱間圧延および冷間圧延を行なって所定の板厚とし、かつ必要に応じて熱間圧延と冷間圧延との間あるいは冷間圧延の中途において中間焼鈍を行ない、冷間圧延後に溶体化処理を行なって焼入れるのが通常である。しかしながらこのような従来の一般的な製造方法では、最近の自動車用ボディシートに要求される特性を充分に満足させることは困難である。
【０００５】
すなわち、最近ではコストの一層の低減のためにさらに薄肉化することが強く要求されており、そのため薄肉でも充分な強度が得られるように、一層の高強度化が求められているが、この点で従来の一般的な製造方法によって得られたＡｌ−Ｍｇ−Ｓｉ系合金板では不充分であった。
【０００６】
また塗装焼付については、省エネルギおよび生産性の向上、さらには高温に曝されることが好ましくない樹脂等の材料との併用などの点から、従来よりも焼付温度を低温化し、また焼付時間も短時間化する傾向が強まっている。そのため従来の一般的な製法により得られたＡｌ−Ｍｇ−Ｓｉ系合金板では、塗装焼付時の硬化（焼付硬化）が不足し、塗装焼付後に充分な高強度が得難くなる問題が生じていた。
【０００７】
また従来のＡｌ−Ｍｇ−Ｓｉ系合金板と製法では、塗装焼付後に高強度を得るために焼付硬化性を高めようとすれば、素材の延性と曲げ加工性が低下し、また板製造後に室温に放置した場合に自然時効により硬化が生じやすくなり、そのため成形性が阻害されがちであるという問題もある。
【０００８】
【発明が解決しようとする課題】
本発明は以上の事情を背景としてなされたもので、良好な成形加工性特に良好な曲げ加工性を有すると同時に、焼付硬化性が優れていて、塗装焼付時における強度上昇が高く、しかも板製造後の室温での経時的な変化が少なく、長期間放置した場合でも自然時効による硬化に起因する成形性の低下が少ない成形加工用アルミニウム合金板の製造方法を提供することを目的とするものである。
【０００９】
【課題を解決するための手段】
前述のような課題を解決するべく本発明者等が実験・検討を重ねた結果、Ａｌ−Ｍｇ−Ｓｉ系合金の成分組成を適切に選択すると同時に、板製造プロセス中において、溶体化処理後に適切な熱処理を行なうことによって、前述の課題を解決し得ることを見出し、この発明をなすに至った。
【００１０】
具体的には、請求項１の発明は、
Ｍｇ０．３〜１．５％（重量％、以下同じ）、Ｓｉ０．３〜２．０％を含有し、Ｍｎ０．０３〜０．４％、Ｃｒ０．０３〜０．４％、Ｚｒ０．０３〜０．４％、Ｖ０．０３〜０．４％、Ｆｅ０．０３〜０．５％、Ｔｉ０．００５〜０．２％、Ｚｎ０．０３〜２．５％のうちから選ばれた１種または２種以上を含有し、さらにＣｕが０．１％未満に規制され、残部がＡｌおよび不可避的不純物よりなるアルミニウム合金を素材とし、鋳塊に均質化処理、熱間圧延および冷間圧延を行ない、所要の板厚の圧延板とした後、その圧延板に対し、４８０℃以上の温度で５分以内の溶体化処理を行なってから１００℃／分以上の冷却速度で４５℃以上７５℃未満の温度範囲まで冷却して、この温度範囲内で５秒以上の保持を行ない、かつその保持時間の上限を、合金の0.2％耐力が１００ＭＰａ以下になるように規制し、続いて７５℃以上８５℃未満の範囲内の温度に加熱して、この温度範囲で２時間以上保持する安定化処理を行なうことを特徴とする、室温(０〜４０℃)での経時変化が少なくかつ成形性および焼付硬化性に優れた成形加工用アルミニウム合金板の製造方法である。
【００１１】
また請求項２の発明は、上記請求項１の、熱間圧延と冷間圧延との間、あるいは冷間圧延途中において４５０〜５８０℃の温度範囲で５分以内の中間焼鈍を施すことを特徴とする室温(０〜４０℃)での経時変化が少なくかつ成形性および焼付硬化性に優れた成形加工用アルミニウム合金板の製造方法である。
【００１２】
【発明の実施の形態】
先ずこの発明の製造方法で用いる合金の成分組成限定理由について説明する。
Ｍｇ：
Ｍｇはこの発明で対象としている系の合金で基本となる合金元素であって、Ｓｉと共同して強度向上に寄与する。Ｍｇ量が０．３％未満では塗装焼付時に析出硬化によって強度向上に寄与するＭｇ2Ｓｉの生成量が少なくなるため、充分な強度向上が得られず、一方１．５％を越えれば成形性が低下するから、Ｍｇ量は０．３〜１．５％の範囲内とする。
Ｓｉ：
Ｓｉもこの発明の系の合金で基本となる合金元素であって、Ｍｇと共同して強度向上に寄与する。またＳｉは、鋳造時に金属Ｓｉの晶出物として生成され、その金属Ｓｉ粒子の周囲が加工によって変形されて、溶体化処理の際に再結晶核の生成サイトとなるため、再結晶組織の微細化にも寄与する。Ｓｉが０．３％未満では上記の効果が充分に得られず、一方２．０％を越えれば粗大Ｓｉが生じて合金の靭性低下を招く。したがってＳｉは０．３〜２．０％の範囲内とする。
【００１３】
Ｃｕ：
Ｃｕはこの発明の系の合金で必須な元素ではなく、かえって０．１％以上になると合金の耐糸錆性が劣化するため、Ｃｕの含有量は０．１％未満に規制する。
【００１４】
Ｍｎ，Ｃｒ，Ｚｒ，Ｖ，Ｔｉ，Ｆｅ，Ｚｎ：
これらは強度向上や結晶粒微細化のために１種または２種以上添加される。
これらのうち、Ｍｎ，Ｃｒ，Ｚｒ，Ｖはいずれも強度向上と結晶粒の微細化および組織の安定化に効果がある元素であり、いずれも含有量が０．０３％未満では上記の効果が充分に得られず、一方それぞれ０．４％を越えれば上記の効果が飽和するばかりでなく、巨大金属間化合物が生成されて成形性に悪影響を及ぼすおそれがあり、したがってＭｎ，Ｃｒ，Ｚｒ，Ｖはいずれも０．０３〜０．４％の範囲内とする。
またＴｉも強度向上と鋳塊組織の微細化に有効な元素であり、その含有量が０．００５％未満では充分な効果が得られず、一方０．２％を越えればＴｉ添加の効果が飽和するばかりでなく、巨大晶出物が生じるおそれがあるから、Ｔｉは０．００５〜０．２％の範囲内とする。
そしてまたＦｅも強度向上と結晶粒微細化に有効な元素であり、その含有量が０．０３％未満では充分な効果が得られず、一方０．５％を越えれば成形性が低下するおそれがあり、したがってＦｅは０．０３〜０．５％の範囲内とする。
Ｚｎは時効硬化による強度向上と表面処理性の向上のために添加される。含有量が０．０３％未満では上記の効果が充分に得られず、一方それぞれ２．５％を越えれば、成形性が低下するからＺｎ量は０．０３から２．５％とする。
なおこれらのＭｎ，Ｃｒ，Ｚｒ，Ｖ，Ｔｉ，Ｆｅ，Ｚｎの範囲は、積極的な添加元素としてこれらの元素を含む場合について示したものであり、いずれもその下限値よりも少ない量を不純物として含有していることは特に支障ない。特に、０．０３％未満のＦｅは、通常のアルミ地金を用いれば不可避的に含有されるのが通常である。
【００１５】
さらに高温時効促進元素あるいは室温時効抑制元素であるＡｇ，Ｉｎ，Ｃｄ，Ｂｅ，Ｓｎの添加は０．３％以下なら、特に支障ない。
以上の各元素のほかは、基本的にはＡｌおよび不可避的不純物とすれば良い。一般に結晶粒微細化のために前述のＴｉと同時にＢを添加することもあり、この発明の場合もＴｉとともに５００ｐｐｍ以下のＢを添加することは許容される。
【００１６】
次にこの発明の方法における製造プロセスについて説明する。
鋳造、均質化処理、熱間圧延、冷間圧延の工程は従来の一般的なＪＩＳ ６０００番系のＡｌ−Ｍｇ−Ｓｉ系合金のそれと同様であれば良い。
すなわち、ＤＣ鋳造法等によって鋳造した後、常法により均質化処理を施し、熱間圧延および冷間圧延を行なって所要の板厚とすれば良い。
【００１７】
ただし、請求項２においては、熱間圧延と冷間圧延との間、あるいは冷間圧延の中途において４５０〜５８０℃の温度範囲で５分以内の中間焼鈍を行なう。
この中間焼鈍は熱間圧延で残存された結晶組織、結晶方位などを新たな再結晶で変化させ、溶体化処理と組み合わせて板の集合組織を制御し、成形性の向上に寄与する。また、この処理は溶体化処理を行う前により多くのＭｇとＳｉ原子の固溶量を確保し、溶体化処理の負荷を低減させる役割がある。
中間焼鈍温度は４５０℃未満では、上記の効果が不十分で、５８０℃を越えると共晶融解、再結晶粒粗大化の恐れがあるから中間焼鈍温度は４５０〜５８０℃とする。
中間焼鈍時間は５分を越えると上記の効果が飽和し、経済性を損なうから、中間焼鈍の時間は５分以内とする。また、冷却速度が１０℃／分以下では、冷却中に多量の析出物が生じて、固溶量の低下につながり、結果的に塗装焼付硬化性に悪影響を及ぼす。したがって、冷却速度は１０℃／分以上とする。
【００１８】
上述のようにして所要の製品板厚とした後、４８０℃以上の温度で５分以内の溶体化処理を行なう。この溶体化処理は、Ｍｇ2Ｓｉ、単体Ｓｉ等をマトリックスに固溶させ、これにより焼付硬化性を付与して塗装焼付後の強度向上を図るために重要な工程である。 この工程はＭｇ2Ｓｉ、単体Ｓｉ粒子等の固溶により、第二相粒子の分布密度が低下し、延性と曲げ性の向上にも寄与し、また、再結晶化により全般に良好な成形性を得るための工程でもある。
溶体化処理温度が４８０℃未満では室温の経時変化の抑制に関しては有利と思われるが、Ｍｇ2Ｓｉ、Ｓｉなどの固溶量が少なく、充分な焼付硬化性が得られないばかりではなく、延性と曲げ性も著しく悪化する。
一方、溶体化処理温度の上限は特に規定しないが、共晶融解の発生のおそれや再結晶粒粗大化等を考慮して、通常は５８０℃以下とすることが望ましい。
また溶体化処理の時間は５分を越えると、溶体化効果が飽和し、経済性を損なうばかりではなく、結晶粒の粗大化の恐れもあるから溶体化処理の時間は５分以内とする。
【００１９】
溶体化処理後には、１００℃／分以上の冷却速度で、４５〜７５℃の温度範囲まで冷却（焼入れ）する。
ここで、溶体化処理後の冷却速度が１００℃／分未満では、冷却中にＭｇ2Ｓｉあるいは単体Ｓｉが粒界に多量に析出してしまい、成形性が低下すると同時に、焼付硬化性が低下して塗装焼付時の充分な強度向上が望めなくなる。
【００２０】
４５℃以上７５℃未満の温度範囲まで冷却（焼入）した後は、４５℃以上７５℃未満の温度範囲内で時間Ｔだけ保持する。この保持時間Ｔは下限を５秒とし、上限（Ｔmax）は合金の0.2％耐力が１００ＭＰａ以下になるように調整する。
そしてこのように４５℃以上７５℃未満の温度範囲での５秒〜Ｔmaxの保持の後、改めて７５℃以上８５℃未満の範囲内の温度に加熱して、この温度範囲内で２時間以上保持する安定化処理を行なう。
【００２１】
このように溶体化処理後に４５℃以上７５℃未満まで冷却して５秒〜Ｔmaxの保持を行なう理由は次の通りである。
すなわち、溶体化処理後、特に１００℃／分以上の冷却速度で４５℃未満の室温に冷却した場合には、室温クラスターが生成される。この室温クラスターは強度に寄与するＧ．Ｐ．ゾーンに移行しにくいため、塗装焼付硬化性に不利となる。
一方、溶体化処理後に７５℃以上の温度範囲に冷却してそのまま保持した場合には、高温クラスターあるいはＧ．Ｐ．ゾーンが生成され、塗装焼付硬化性に対しては有利となるが、安定化処理後の室温時効による経時変化が大きく、成形性に悪影響を与える。
したがって成形性と塗装焼付硬化性とのバランスの観点から、溶体化処理後には４５℃以上７５℃未満の温度範囲内に焼入する必要がある。すなわち、溶体化処理後には、４５℃以上７５℃未満の温度範囲内に冷却することによって、成形性と塗装焼付硬化性との両者を満たすことができるのである。
【００２２】
４５℃以上７５℃未満の温度範囲での保持時間Ｔが５秒以下では、上述の効果、特に室温時効の抑制の効果が得られない。
一方、４５℃以上７５℃未満の温度範囲での保持時間Ｔが長時間にわたれば、室温クラスターに近い構造と性質を有するクラスターあるいはＧ．Ｐ．ゾーンが多量に生成されて、その後の塗装焼付硬化性が低下してしまう。このように長時間保持した場合の保持時間Ｔの影響は、合金成分や溶体化温度などによって変わるから、保持時間Ｔの上限は一律に定めることはできないが、合金の耐力を指標として定めることができる。
すなわち、４５℃以上７５℃未満での保持時間が長くなってその温度範囲での時効によってクラスターあるいはＧ．Ｐ．ゾーンが多量に生成されれば合金の耐力も高くなるから、４５℃以上７５℃未満の温度範囲で保持時の耐力を指標として保持時間Ｔの上限Ｔmaxを定めることができ、本発明者等の実験によれば、0.2％耐力が１００ＭＰａ以下の範囲内となるように保持時間Ｔの上限Ｔmaxを規制することが有効であることが判明した。なおこの耐力は、溶体化処理後、１００℃／分以上の冷却速度で４５〜７５℃の温度範囲に冷却し、その温度範囲で保持した状態での0.2％耐力を意味する。
したがって実際の操業にあたっては、この耐力が１００ＭＰａ以下となるような保持時間Ｔの上限Ｔmaxの具体値を、合金成分や溶体化処理温度などの実際の具体的条件に応じて予備実験を行なうことにより求めておけば良い。
なお、本願組成とここまでの工程の組み合わせの範囲内では保持時間Ｔmaxは３日間が最大となる。
【００２３】
上述のような４５℃以上７５℃未満の温度範囲での保持の後には、室温まで冷却することなく、改めて７５℃以上８５℃未満の範囲内の温度に加熱して安定化処理を行なう。
この安定化処理は、最終的にクラスターあるいはＧ．Ｐ．ゾーンの安定性を向上させ、板製造後の経時変化を抑制して、充分な焼付硬化性を確保するとともに良好な成形加工性を得るために必要な工程であり、この安定化処理は、７５℃以上８５℃未満の範囲内の温度に２時間以上保持の条件とする必要がある。
安定化処理の温度が７５℃未満では上記の効果が充分に得られず、一方８５℃以上では高温時効によって粒界析出の傾向が強くなり、成形性特に曲げ性が低下してしまう。
また安定化処理における７５℃以上８５℃未満の範囲内の温度での保持時間が２時間未満では、その後の室温での経時変化が速くなって成形性と焼付硬化性が悪くなる。
【００２４】
以上のようにこの発明の製造方法では、合金の成分組成を適切に調整するとともに、製造プロセス中において、４８０℃以上の温度での溶体化処理、および４５℃以上７５℃未満の温度範囲への冷却（焼入れ）とその温度範囲での適切な保持の後に改めて７５℃以上８５℃未満の条件で安定化処理を施すことにより、成形性特に曲げ性が改善され、板製造後の室温での経時変化、すなわち室温での自然時効の進行を阻止することも可能となり、その結果、板製造後に長期間放置されてから成形加工、塗装焼付を施す場合でも、良好な成形性、優れた焼付硬化性を充分に確保することが可能となったのである。
【００２５】
【実施例】
表１に示す本発明成分組成範囲内の合金記号Ａ１〜Ａ２合金、および本発明成分組成範囲外の合金記号Ｂ１〜Ｂ２の合金について、それぞれ常法に従ってＤＣ鋳造法により鋳造し、得られた鋳塊に５３０℃×５時間の均質化処理を施してから、熱間圧延を開始し、続いて冷間圧延を行なった。冷間圧延途中に種々の中間焼鈍を行った。最終的に厚さ１ｍｍの圧延板とした。次いで各圧延板に対し、種々の溶体化処理を行なってから、１００℃／分以上の冷却速度で種々の温度まで焼入れして、その焼入温度で保持し、さらに７５℃以上８５℃未満で安定化処理を行なった。詳細な製造条件を表２に示す。
【００２６】
以上のように安定化処理を行なって得られた板を、さらに室温に１日もしくは９０日放置した各板について、それぞれ１８０℃×３０分の加熱の塗装焼付処理を施し、その焼付前の機械的特性および成形性と、焼付後の機械的特性を調べた。その結果を表３に示す。
【００２７】
【表１】
【表２】
【表３】
製造番号１と２は、合金の成分組成がこの発明で規定する範囲内でかつ製造条件もこの発明で規定する条件を満たしたものであるが、この場合は、塗装焼付前の伸びおよびエリクセン値が充分に高くて曲げ性が優れ、かつ焼付硬化性が高くて塗装焼付時に大きな強度上昇が生じており、特に板製造後９０日室温に放置した場合においても、伸びおよびエリクセン値の低下が少なくて曲げ性が低下せず、かつ充分な焼付硬化性を示した。
【００３１】
これに対し製造番号３〜４は、合金の成分組成はこの発明で規定する範囲内であるが、製造条件がこの発明で規定する条件を満たさなかったものである。
製造番号３（合金記号Ａ１）は、溶体化処理後室温（３０℃）まで冷却したものであるが、この場合には同じ合金（合金記号Ａ１）を用いた本発明例（製造番号１）と比較して、焼付硬化性が大幅に劣った。
また製造番号４は、中間焼鈍温度と溶体化温度が低く、冷却後１２０℃での保持で、保持時の合金の耐力が１００Ｍｐａを越えてしまったものであるが、この場合には同じ合金を用いた本発明例（製造番号２）と比較して焼付硬化性と曲げ性が劣った。
【００３２】
一方、製造番号５，６はいずれも成分組成がこの発明で規定する範囲を外れた合金について、この発明で規定する範囲内の条件のプロセスを適用したものである。
製造番号５（合金記号Ｂ１)は、焼付硬化性があるが、曲げ性が劣った。
製造番号６（合金記号Ｂ２)は、素材強度が低いばかりでなく、曲げ性も劣り、塗装焼付後の強度も充分ではなかった。
【００３３】
【発明の効果】
以上詳細に説明したように、本発明の成形加工用アルミニウム合金板の製造方法によれば、高い焼付硬化性が維持されながら、延性と曲げ性が優れていて、塗装焼付後の強度が著しく高く、しかも室温での経時変化が少なくて、板製造後に室温で長期間放置した場合にも成形性の低下が少ないとともに焼付硬化性の変化も少ない、安定な成形加工用アルミニウム合金板を得ることができる。
したがって自動車用ボディシート、家電部品、各種機械器具部品、そのほか成形加工および塗装焼付を施して用いる用途のアルミニウム合金の製造に最適である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an aluminum alloy plate used as a material for automobile body sheets, parts, various machinery and appliances, home appliance parts, and the like, and is particularly good in formability. In addition, the present invention relates to a method for producing an aluminum alloy sheet for forming that has high strength after baking and has little change with time at room temperature.
[0002]
[Prior art]
Conventionally, cold rolled steel sheets have often been mainly used for automobile body sheets, but recently, aluminum alloy rolled sheets have been promoted from the viewpoint of reducing the weight of the vehicle body. Since automobile body sheets are used after being pressed, it is required that they have excellent moldability, that there is no Luders mark during molding, and that they must have high strength. In particular, since coating baking is performed, it is required that high strength be obtained after baking.
[0003]
Conventionally, as such an aluminum alloy for an automobile body sheet, an aging JIS6000 series alloy, that is, an Al-Mg-Si series alloy is mainly used. This aging Al-Mg-Si alloy has a relatively low strength and excellent formability during molding before coating baking, while it is aged by heating during coating baking and has a strength after coating baking. In addition to the advantage that it becomes higher, it has the advantage that a Ruders mark does not occur.
[0004]
By the way, as a method for producing an Al-Mg-Si alloy plate that is expected to age harden during paint baking, the ingot is subjected to homogenization heat treatment, and then subjected to hot rolling and cold rolling to a predetermined thickness, and In general, intermediate annealing is performed between hot rolling and cold rolling or in the middle of cold rolling as necessary, and a solution treatment is performed after cold rolling and quenching. However, it is difficult to satisfactorily satisfy the characteristics required for a recent automobile body sheet by such a conventional general manufacturing method.
[0005]
That is, recently, there has been a strong demand for further thinning in order to further reduce the cost. Therefore, there is a demand for further strengthening so that sufficient strength can be obtained even with a thin wall. However, the Al—Mg—Si based alloy plate obtained by the conventional general manufacturing method is insufficient.
[0006]
In addition, with regard to paint baking, the baking temperature is lower than before, and the baking time is also shortened from the standpoints of energy saving, productivity improvement, and combined use with materials such as resins that are not preferably exposed to high temperatures. There is an increasing tendency to shorten the time. For this reason, the Al-Mg-Si alloy plate obtained by the conventional general manufacturing method has a problem that it is difficult to obtain sufficient high strength after baking after painting baking because the curing (baking hardening) during coating baking is insufficient. .
[0007]
In addition, in the conventional Al-Mg-Si alloy plate and manufacturing method, if the bake hardenability is increased in order to obtain high strength after coating baking, the ductility and bending workability of the material are reduced, and the room temperature is increased after the plate is manufactured. When it is left as it is, it tends to be hardened due to natural aging, so that there is a problem that moldability tends to be hindered.
[0008]
[Problems to be solved by the invention]
The present invention has been made against the background described above, and has good moldability, particularly good bending workability, and at the same time has excellent bake hardenability, high strength increase during paint baking, and plate production. It is intended to provide a method for producing an aluminum alloy sheet for forming with less change over time at room temperature and less deterioration in formability due to hardening due to natural aging even when left for a long time. is there.
[0009]
[Means for Solving the Problems]
As a result of repeated experiments and examinations by the present inventors to solve the above-mentioned problems, the component composition of the Al-Mg-Si alloy is appropriately selected, and at the same time, after the solution treatment in the plate manufacturing process. It has been found that the above-mentioned problems can be solved by performing a proper heat treatment, and the present invention has been made.
[0010]
Specifically, the invention of claim 1
Mg 0.3-1.5% (% by weight, the same shall apply hereinafter), Si 0.3-2.0%, Mn 0.03-0.4%, Cr 0.03-0.4%, Zr 0.03- One or two selected from 0.4%, V0.03-0.4%, Fe0.03-0.5%, Ti0.005-0.2%, Zn0.03-2.5% It contains more than seeds, further Cu is regulated to less than 0.1%, and the balance is made of an aluminum alloy consisting of Al and inevitable impurities, and the ingot is subjected to homogenization treatment, hot rolling and cold rolling, After forming a rolled sheet having a required sheet thickness, the sheet is subjected to a solution treatment within 5 minutes at a temperature of 480 ° C. or higher, and then at a cooling rate of 100 ° C./minute or higher and lower than 45 ° C. and lower than 75 ° C. Cool to the temperature range and hold for 5 seconds or more within this temperature range. The limit is regulated so that the 0.2% proof stress of the alloy is 100 MPa or less, and then the alloy is heated to a temperature in the range of 75 ° C. or higher and lower than 85 ° C., and a stabilization treatment is performed for holding at this temperature range for 2 hours or longer. This is a method for producing an aluminum alloy sheet for forming with little change over time at room temperature (0 to 40 ° C.) and excellent formability and bake hardenability.
[0011]
The invention of claim 2 is characterized in that the intermediate annealing is performed within a temperature range of 450 to 580 ° C. within 5 minutes between the hot rolling and the cold rolling or in the middle of the cold rolling. This is a method for producing an aluminum alloy sheet for forming with little change over time at room temperature (0 to 40 ° C.) and excellent formability and bake hardenability.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
First, the reasons for limiting the component composition of the alloy used in the manufacturing method of the present invention will be described.
Mg:
Mg is an alloy element that is a basic alloy of the system targeted by the present invention, and contributes to strength improvement in cooperation with Si. If the Mg content is less than 0.3%, the amount of Mg 2 Si that contributes to strength improvement due to precipitation hardening during baking is reduced, so that sufficient strength improvement cannot be obtained. Therefore, the amount of Mg is set in the range of 0.3 to 1.5%.
Si:
Si is also an alloy element that is fundamental in the alloy of the present invention, and contributes to strength improvement in cooperation with Mg. In addition, Si is produced as a crystallized product of metal Si at the time of casting, and the periphery of the metal Si particles is deformed by processing and becomes a recrystallization nucleus generation site during solution treatment. It also contributes to If the Si content is less than 0.3%, the above effect cannot be obtained sufficiently. On the other hand, if the Si content exceeds 2.0%, coarse Si is produced and the toughness of the alloy is reduced. Therefore, Si is within the range of 0.3 to 2.0%.
[0013]
Cu:
Cu is not an essential element in the alloy of the present invention. If the content is 0.1% or more, the rust resistance of the alloy deteriorates, so the Cu content is restricted to less than 0.1%.
[0014]
Mn, Cr, Zr, V, Ti, Fe, Zn:
One or more of these are added to improve the strength and refine the crystal grains.
Among these, Mn, Cr, Zr, and V are all elements that are effective in improving the strength, refining the crystal grains, and stabilizing the structure, and if the content is less than 0.03%, the above effects are achieved. On the other hand, if each exceeds 0.4%, not only the above effects are saturated, but also a large intermetallic compound may be produced, which may adversely affect the formability. Therefore, Mn, Cr, Zr, V is within the range of 0.03 to 0.4%.
Ti is also an element effective for improving the strength and refining the ingot structure, and if its content is less than 0.005%, a sufficient effect cannot be obtained. In addition to being saturated, there is a possibility that a giant crystallized product may be formed. Therefore, Ti is set within a range of 0.005 to 0.2%.
Fe is also an element effective for strength improvement and grain refinement, and if its content is less than 0.03%, sufficient effects cannot be obtained, while if it exceeds 0.5%, moldability may be reduced. Therefore, Fe is within the range of 0.03 to 0.5%.
Zn is added in order to improve the strength by age hardening and improve the surface treatment. If the content is less than 0.03%, the above effects cannot be obtained sufficiently. On the other hand, if the content exceeds 2.5%, the moldability is lowered, so that the Zn content is 0.03 to 2.5%.
These ranges of Mn, Cr, Zr, V, Ti, Fe, and Zn are shown for cases where these elements are included as active additive elements, and all of them are less than the lower limit. It is not particularly difficult to contain as. In particular, Fe of less than 0.03% is usually inevitably contained if a normal aluminum ingot is used.
[0015]
Furthermore, if the addition of Ag, In, Cd, Be, Sn, which is a high temperature aging promoting element or a room temperature aging suppressing element, is 0.3% or less, there is no particular problem.
In addition to the above elements, basically, Al and inevitable impurities may be used. In general, B may be added simultaneously with the above-mentioned Ti for crystal grain refinement, and in the case of this invention, adding 500 ppm or less of B together with Ti is allowed.
[0016]
Next, the manufacturing process in the method of the present invention will be described.
The steps of casting, homogenizing treatment, hot rolling, and cold rolling may be the same as those of conventional general JIS 6000 series Al—Mg—Si alloys.
That is, after casting by a DC casting method or the like, homogenization is performed by a conventional method, and hot rolling and cold rolling are performed to obtain a required plate thickness.
[0017]
However, in claim 2, intermediate annealing is performed within 5 minutes in a temperature range of 450 to 580 ° C. between hot rolling and cold rolling or in the middle of cold rolling.
This intermediate annealing changes the crystal structure, crystal orientation, and the like remaining in the hot rolling by new recrystallization, controls the texture of the plate in combination with the solution treatment, and contributes to the improvement of formability. In addition, this treatment has a role of securing a larger amount of Mg and Si atoms before the solution treatment and reducing the load of the solution treatment.
If the intermediate annealing temperature is less than 450 ° C, the above effect is insufficient, and if it exceeds 580 ° C, eutectic melting and recrystallization grain coarsening may occur, so the intermediate annealing temperature is set to 450 to 580 ° C.
If the intermediate annealing time exceeds 5 minutes, the above effect is saturated and the economic efficiency is impaired. Therefore, the intermediate annealing time is set within 5 minutes. On the other hand, when the cooling rate is 10 ° C./min or less, a large amount of precipitates are generated during cooling, leading to a decrease in the amount of solid solution, resulting in an adverse effect on the bake hardenability. Accordingly, the cooling rate is 10 ° C./min or more.
[0018]
After the required product thickness is obtained as described above, solution treatment is performed at a temperature of 480 ° C. or more for 5 minutes or less. This solution treatment is an important process for solid-dissolving Mg 2 Si, elemental Si, etc. in the matrix, thereby imparting bake hardenability and improving the strength after coating baking. This process contributes to the improvement of ductility and bendability by reducing the distribution density of the second phase particles due to solid solution of Mg 2 Si, simple substance Si particles, etc. Also, generally good formability due to recrystallization. It is also a process for obtaining.
When the solution treatment temperature is less than 480 ° C., it seems that it is advantageous for suppressing the aging change at room temperature, but not only the amount of solid solution of Mg 2 Si, Si, etc. is small and sufficient bake hardenability cannot be obtained, but also ductility. And the bendability is also greatly deteriorated.
On the other hand, the upper limit of the solution treatment temperature is not particularly defined, but it is usually preferably 580 ° C. or less in consideration of the possibility of eutectic melting and coarsening of recrystallized grains.
If the solution treatment time exceeds 5 minutes, the solution treatment effect is saturated, not only the economic efficiency is impaired, but also the crystal grains may be coarsened, so the solution treatment time is set within 5 minutes.
[0019]
After the solution treatment, it is cooled (quenched) to a temperature range of 45 to 75 ° C. at a cooling rate of 100 ° C./min or more.
Here, when the cooling rate after the solution treatment is less than 100 ° C./min, Mg 2 Si or simple substance Si precipitates in the grain boundary during cooling, and at the same time the moldability is lowered and the bake hardenability is lowered. As a result, it is impossible to expect a sufficient improvement in strength during baking.
[0020]
After cooling (quenching) to a temperature range of 45 ° C. or higher and lower than 75 ° C., the temperature is maintained for 45 hours within a temperature range of 45 ° C. or higher and lower than 75 ° C. The holding time T has a lower limit of 5 seconds, and the upper limit (Tmax) is adjusted so that the 0.2% proof stress of the alloy is 100 MPa or less.
Then, after holding for 5 seconds to Tmax in the temperature range of 45 ° C. or more and less than 75 ° C., the sample is heated again to a temperature in the range of 75 ° C. or more and less than 85 ° C., and kept in this temperature range for 2 hours or more. Stabilization processing is performed.
[0021]
Thus, the reason for cooling to 45 ° C. or higher and lower than 75 ° C. after the solution treatment and holding for 5 seconds to Tmax is as follows.
That is, after solution treatment, a room temperature cluster is generated particularly when cooling to a room temperature of less than 45 ° C. at a cooling rate of 100 ° C./min or more. This room temperature cluster contributes to strength. P. Since it is difficult to shift to the zone, it is disadvantageous for paint bake hardenability.
On the other hand, when the solution is cooled to a temperature range of 75 ° C. or higher and kept as it is after the solution treatment, the high temperature cluster or G.P. P. A zone is generated, which is advantageous for paint bake hardenability, but a change with time due to room temperature aging after the stabilization treatment is large, which adversely affects moldability.
Therefore, from the viewpoint of the balance between moldability and paint bake hardenability, it is necessary to quench within a temperature range of 45 ° C. or more and less than 75 ° C. after the solution treatment. That is, after the solution treatment, both moldability and paint bake hardenability can be satisfied by cooling within a temperature range of 45 ° C. or more and less than 75 ° C.
[0022]
When the holding time T in the temperature range of 45 ° C. or more and less than 75 ° C. is 5 seconds or less, the above-described effects, particularly the effect of suppressing room temperature aging cannot be obtained.
On the other hand, if the holding time T in a temperature range of 45 ° C. or higher and lower than 75 ° C. is long, a cluster having a structure and properties close to room temperature clusters or G.P. P. A large amount of zones are generated, and the subsequent bake hardenability decreases. Since the influence of the holding time T in the case of holding for a long time as described above varies depending on the alloy component, the solution temperature, and the like, the upper limit of the holding time T cannot be determined uniformly, but the proof strength of the alloy can be determined as an index. it can.
That is, the retention time at 45 ° C. or higher and lower than 75 ° C. becomes longer, and the cluster or G. P. Since the yield strength of the alloy increases when a large number of zones are generated, the upper limit Tmax of the retention time T can be determined using the yield strength during holding in the temperature range of 45 ° C. or more and less than 75 ° C. as an index. According to experiments, it has been found that it is effective to limit the upper limit Tmax of the holding time T so that the 0.2% proof stress falls within the range of 100 MPa or less. In addition, this yield strength means 0.2% yield strength in the state which cooled to the temperature range of 45-75 degreeC with the cooling rate of 100 degree-C / min or more after solution treatment, and was hold | maintained in the temperature range.
Therefore, in actual operation, a specific value of the upper limit Tmax of the holding time T such that the proof stress is 100 MPa or less is determined by conducting a preliminary experiment in accordance with actual specific conditions such as alloy components and solution treatment temperature. Find it.
It should be noted that the retention time Tmax is maximum for 3 days within the range of the composition of the present application and the steps so far.
[0023]
After holding in the temperature range of 45 ° C. or more and less than 75 ° C. as described above, the stabilization treatment is performed by heating again to a temperature in the range of 75 ° C. or more and less than 85 ° C. without cooling to room temperature.
This stabilization process is finally performed in clusters or G.P. P. This is a step necessary to improve the stability of the zone, suppress the change with time after the production of the plate, ensure sufficient bake hardenability and obtain good molding processability. It is necessary to maintain the temperature within the range of from ℃ to less than 85 ℃ for 2 hours or more.
When the temperature of the stabilization treatment is less than 75 ° C., the above effect cannot be sufficiently obtained. On the other hand, when the temperature is 85 ° C. or more, the tendency of grain boundary precipitation increases due to high-temperature aging, and the formability, particularly bendability, decreases.
Further, if the holding time at a temperature in the range of 75 ° C. or more and less than 85 ° C. in the stabilization treatment is less than 2 hours, then the change with time at room temperature becomes faster and the moldability and bake hardenability deteriorate.
[0024]
As described above, in the production method of the present invention, the alloy composition is appropriately adjusted, and during the production process, solution treatment is performed at a temperature of 480 ° C. or higher, and the temperature range is 45 ° C. or higher and lower than 75 ° C. After cooling (quenching) and proper holding in that temperature range, the formability, especially bendability, is improved by performing a stabilization treatment again under the condition of 75 ° C or more and less than 85 ° C. It is also possible to prevent the progress of natural aging at room temperature, resulting in good formability and excellent bake hardenability even when molding processing and paint baking are performed after leaving the plate for a long period of time. It has become possible to ensure sufficient.
[0025]
【Example】
The alloy symbols A1 to A2 alloys within the composition range of the present invention shown in Table 1 and the alloys symbols B1 to B2 outside the composition range of the present invention were cast by a DC casting method according to a conventional method, respectively, and the obtained castings The lump was homogenized at 530 ° C. for 5 hours, hot rolling was started, and then cold rolling was performed. Various intermediate annealing was performed during the cold rolling. Finally, a rolled plate having a thickness of 1 mm was obtained. Next, each of the rolled plates is subjected to various solution treatments, and then quenched to various temperatures at a cooling rate of 100 ° C./min or more, and held at the quenching temperature. Stabilization was performed. Detailed manufacturing conditions are shown in Table 2.
[0026]
The plate obtained by performing the stabilization treatment as described above is further subjected to a coating baking treatment of 180 ° C. × 30 minutes for each plate left at room temperature for 1 day or 90 days, and the machine before the baking The mechanical properties and formability and mechanical properties after baking were investigated. The results are shown in Table 3.
[0027]
[Table 1]
[Table 2]
[Table 3]
Production Nos. 1 and 2 are those in which the composition of the alloy is within the range defined by the present invention and the production conditions satisfy the conditions defined by the present invention. In this case, the elongation and Erichsen value before baking are applied. Is sufficiently high, has excellent bendability, and has high bake hardenability, resulting in a significant increase in strength during baking, especially when it is left at room temperature for 90 days after the plate is produced. As a result, the bendability did not decrease and sufficient bake hardenability was exhibited.
[0031]
On the other hand, production numbers 3 to 4 are those in which the composition of the alloy is within the range defined by the present invention, but the production conditions did not satisfy the conditions defined by the present invention.
Production number 3 (alloy symbol A1) was cooled to room temperature (30 ° C.) after the solution treatment. In this case, the present invention example using the same alloy (alloy symbol A1) (production number 1) and In comparison, the bake hardenability was significantly inferior.
Production No. 4 has a low intermediate annealing temperature and solution temperature, and the holding strength at 120 ° C. after cooling resulted in the alloy yield strength exceeding 100 Mpa. In this case, the same alloy was used. Bake hardenability and bendability were inferior compared to the inventive example used (Production No. 2).
[0032]
On the other hand, production numbers 5 and 6 are obtained by applying a process having conditions within the range defined by the present invention to an alloy whose component composition is outside the range defined by the present invention.
Production No. 5 (alloy symbol B1) has bake hardenability but poor bendability.
Production No. 6 (alloy symbol B2) was not only low in material strength but also inferior in bendability, and the strength after baking was not sufficient.
[0033]
【The invention's effect】
As described above in detail, according to the method for manufacturing an aluminum alloy sheet for forming according to the present invention, high bake hardenability is maintained, ductility and bendability are excellent, and strength after paint baking is extremely high. In addition, it is possible to obtain a stable aluminum alloy sheet for forming work that has little change over time at room temperature, and has little deterioration in formability and little change in bake hardenability even when left at room temperature for a long time after plate production. it can.
Therefore, it is most suitable for the production of automotive body sheets, home appliance parts, various machine tool parts, and other aluminum alloys that are used after being molded and painted and baked.
Claims (2)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33108595A JP3686146B2 (en) | 1995-11-27 | 1995-11-27 | Method for producing aluminum alloy sheet for forming |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP33108595A JP3686146B2 (en) | 1995-11-27 | 1995-11-27 | Method for producing aluminum alloy sheet for forming |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09143644A JPH09143644A (en) | 1997-06-03 |
| JP3686146B2 true JP3686146B2 (en) | 2005-08-24 |
Family
ID=18239689
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP33108595A Expired - Fee Related JP3686146B2 (en) | 1995-11-27 | 1995-11-27 | Method for producing aluminum alloy sheet for forming |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3686146B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3736594B2 (en) * | 1997-07-10 | 2006-01-18 | 株式会社神戸製鋼所 | Aluminum alloy joined body by mechanical clinch and manufacturing method thereof |
| CH693673A5 (en) * | 1999-03-03 | 2003-12-15 | Alcan Tech & Man Ag | Use of an aluminum alloy of the AlMgSi type for the production of structural components. |
| JP4819233B2 (en) * | 2000-08-30 | 2011-11-24 | 新日本製鐵株式会社 | Aluminum alloy plate with excellent formability |
| PL424248A1 (en) * | 2018-01-11 | 2019-07-15 | Albatros Aluminium Spółka Z Ograniczoną Odpowiedzialnością | Aluminum composite with high kinetic energy cumulation properties and increased mechanical properties |
-
1995
- 1995-11-27 JP JP33108595A patent/JP3686146B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09143644A (en) | 1997-06-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPS62177143A (en) | Aluminum alloy sheet excellent in formability and baking hardening and its production | |
| JP2015040340A (en) | Molding aluminum alloy sheet and method for manufacturing the same | |
| JP4086350B2 (en) | Method for producing aluminum alloy sheet for forming | |
| JPH06240424A (en) | Production of aluminum alloy sheet excellent in formability and baking hardenability | |
| JP3845312B2 (en) | Aluminum alloy plate for forming and method for producing the same | |
| JP3849095B2 (en) | Aluminum alloy plate for forming and method for producing the same | |
| JPH083702A (en) | Production of aluminum alloy sheet material excellent in formability and heating hardenability | |
| JP2626958B2 (en) | Method for producing aluminum alloy sheet excellent in formability and bake hardenability | |
| JPH09249950A (en) | Production of aluminum alloy sheet excellent in formability and hardenability in coating/baking | |
| JPH08176764A (en) | Production of aluminum alloy sheet for forming | |
| JP3686146B2 (en) | Method for producing aluminum alloy sheet for forming | |
| JPH0874014A (en) | Production of aluminum alloy sheet having high formability and good baking hardenability | |
| JP2000239811A (en) | Manufacture for aluminum alloy sheet excellent in formability | |
| JP2000160310A (en) | Production of aluminum alloy sheet suppressed in cold aging property | |
| JP2599861B2 (en) | Manufacturing method of aluminum alloy material for forming process excellent in paint bake hardenability, formability and shape freezing property | |
| JP2004124175A (en) | Method for manufacturing 6000 system alloy plate for forming excellent in formability, baking hardenability, and springback characteristic | |
| JPH0547615B2 (en) | ||
| JP3359428B2 (en) | Manufacturing method of aluminum alloy sheet for forming | |
| JPH0788558B2 (en) | Method for producing aluminum alloy sheet excellent in formability and bake hardenability | |
| JPH04365834A (en) | Aluminum alloy sheet for press forming excellent in hardenability by low temperature baking and its production | |
| JPH07228957A (en) | Production of aluminum alloy sheet having excellent formability and quench-hardenability | |
| JPH04263034A (en) | Aluminum alloy sheet for press forming excellent in baking hardenability and its production | |
| JPH062092A (en) | Method for heat-treating high strength and high formability aluminum alloy | |
| JP2007239005A (en) | Method for producing 6000 series aluminum alloy sheet having excellent room temperature non-aging property, formability and coating/baking hardenability | |
| JPH0860314A (en) | Production of aluminum alloy sheet for forming |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20040406 |
|
| 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: 20050531 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20050602 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080610 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090610 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110610 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110610 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140610 Year of fee payment: 9 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |