JP2003277868A - Aluminum alloy forging having excellent stress corrosion cracking resistance and stock for the forging - Google Patents
Aluminum alloy forging having excellent stress corrosion cracking resistance and stock for the forgingInfo
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- JP2003277868A JP2003277868A JP2002076567A JP2002076567A JP2003277868A JP 2003277868 A JP2003277868 A JP 2003277868A JP 2002076567 A JP2002076567 A JP 2002076567A JP 2002076567 A JP2002076567 A JP 2002076567A JP 2003277868 A JP2003277868 A JP 2003277868A
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- aluminum alloy
- forging
- corrosion cracking
- stress corrosion
- crystal
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Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、輸送機の構造材部
品に好適な、耐応力腐食割れ性などの耐食性に優れたAl
-Mg-Si系高強度高靱性アルミニウム合金鍛造材 (以下、
アルミニウムを単にAlと言う) および鍛造材用素材に関
するものである。TECHNICAL FIELD The present invention relates to an Al having excellent corrosion resistance such as stress corrosion cracking resistance, which is suitable for structural material parts of transport aircraft.
-Mg-Si based high strength and high toughness aluminum alloy forgings (hereinafter,
Aluminum is simply referred to as Al) and forging material.
【0002】[0002]
【従来の技術】周知の通り、車両、船舶、航空機、自動
二輪あるいは自動車などの輸送機の構造材乃至部品用と
して、JIS 6000系(Al-Mg-Si 系) などのAl合金が使用さ
れている。このJIS 6000系Al合金は、比較的耐食性にも
優れており、また、スクラップをJIS 6000系Al合金溶解
原料として再利用できるリサイクル性の点からも優れて
いる。2. Description of the Related Art As is well known, JIS 6000 series (Al-Mg-Si series) and other Al alloys are used for structural materials and parts of vehicles such as vehicles, ships, aircraft, motorcycles and automobiles. There is. This JIS 6000 series Al alloy is relatively excellent in corrosion resistance, and is also excellent in terms of recyclability in which scrap can be reused as a JIS 6000 series Al alloy melting raw material.
【0003】前記輸送機の構造材を例にとると、製造コ
ストの低減や、複雑形状部品への加工の点から、Al合金
鋳造材やAl合金鍛造材が用いられる。この内、より高強
度で高靱性などの機械的性質が要求される部品には、Al
合金鍛造材が主として用いられる。そして、これらAl合
金鍛造材は、Al合金鋳造材を均質化熱処理後、メカニカ
ル鍛造、油圧鍛造などの熱間鍛造し、その後T6などの調
質処理が施されて製造される。なお、鍛造素材には、鋳
造材を一旦押出した押出材が用いられることもある。Taking the structural material of the transportation machine as an example, an Al alloy cast material or an Al alloy forged material is used from the viewpoints of reduction of manufacturing cost and processing into parts having complicated shapes. Of these, Al is used for parts requiring higher strength and mechanical properties such as high toughness.
Alloy forgings are mainly used. These Al alloy forged materials are manufactured by homogenizing heat treatment of the Al alloy cast material, hot forging such as mechanical forging, hydraulic forging, and the like, and then subjected to heat treatment such as T6. The extruded material obtained by extruding the cast material may be used as the forging material.
【0004】近年、これら輸送機の構造材においても、
より薄肉化させた上での高強度化や高靱性化が求められ
ている。しかし、現状でこれら用途に使用されているJI
S 6000系Al合金鍛造材では、どうしても強度や靱性不足
が生じてしまう。In recent years, even in the structural materials of these transport aircraft,
There is a demand for higher strength and higher toughness after being made thinner. However, the JI currently used for these applications
In the S 6000 series Al alloy forged material, strength and toughness inevitably occur.
【0005】このため、従来からAl合金材料の側を改善
することが行われている。例えば、特開平06-256880 号
公報では、Al合金鍛造材用鋳造材として、JIS 6000系(A
l-Mg-Si 系) 鋳造材のMg、Si等の成分を規定するととも
に、晶析出物 (晶出物や析出物) の平均粒径を8 μm 以
下と小さくし、かつデンドライト二次アーム間隔(DAS)
を40μm 以下と細かくして、Al合金鍛造材をより高強度
で高靱性化することが提案されている。For this reason, the Al alloy material side has been conventionally improved. For example, in Japanese Patent Laid-Open No. 06-256880, JIS 6000 series (A
(l-Mg-Si system) The components such as Mg and Si of the cast material are specified, the average grain size of crystal precipitates (crystallized substances and precipitates) is reduced to 8 μm or less, and the dendrite secondary arm interval is set. (DAS)
It has been proposed to make the Al alloy forging material finer with a fineness of 40 μm or less to have higher strength and toughness.
【0006】しかし、この従来技術で得られるAl合金鍛
造材の強度や靱性は、JIS 6061や6151などのAl合金など
よりも向上しているものの、より薄肉化させた上での高
強度化や高靱性化の要求レベルに対しては、今だ不足す
る。However, although the strength and toughness of the Al alloy forged material obtained by this conventional technique are higher than those of Al alloys such as JIS 6061 and 6151, the strength and toughness of the forged material are further reduced after being made thinner. There is still a shortage of the required level of toughness.
【0007】これに対し、本発明者らは、Al合金鍛造材
のより薄肉化させた上での高強度化や高靱性化のため
に、特願平10-238564 号や特願平11-224024 号によっ
て、Mg:0.6〜1.6% (質量% 、以下同じ) 、Si:0.4乃至0.
6 〜1.8%、Cu:0.01 乃至0.1 〜1.0%を含むとともに、Fe
を0.25% 乃至0.30% 以下に規制し、更にMn:0.15 〜0.6
%、Cr:0.1〜0.2%、Zr:0.1〜0.2%の一種または二種以上
を選択的あるいは必須に含み、残部Alおよび不可避的不
純物からなるアルミニウム合金鍛造材であって、Mg2Si
とAl-Fe-Si-(Mn、Cr、Zr) 系などの晶析出物の合計の面
積率が単位面積当たり1.5%以下であり、耐力 (σ0.2)の
平均値が350N/mm2以上およびシャルピー衝撃値の平均値
が30J/cm2 以上を達成できる高強度で高靱性なAl合金鍛
造材を提案した。On the other hand, the inventors of the present invention have proposed Japanese Patent Application No. 10-238564 and Japanese Patent Application No. 11-238564 in order to increase the strength and toughness of the forged Al alloy material after making it thinner. According to No. 224024, Mg: 0.6 to 1.6% (mass%, the same hereinafter), Si: 0.4 to 0.
6 to 1.8%, Cu: 0.01 to 0.1 to 1.0%, and Fe
Is controlled to 0.25% to 0.30% or less, and Mn: 0.15 to 0.6
%, Cr: 0.1 to 0.2%, Zr: 0.1 to 0.2% selectively or indispensably containing one or more kinds, an aluminum alloy forging material consisting of the balance Al and unavoidable impurities, Mg 2 Si
And the total area ratio of crystal precipitates such as Al-Fe-Si- (Mn, Cr, Zr) series is 1.5% or less per unit area, and the average value of proof stress (σ 0.2 ) is 350 N / mm 2 or more and We proposed a high-strength and high-toughness Al alloy forged material that can achieve an average Charpy impact value of 30 J / cm 2 or more.
【0008】これらの発明では、過剰Si量を多くし、あ
るいはCuのような高強度化元素を添加して鍛造材の高強
度化を図るとともに、鋳造材の晶析出物の内、鍛造され
たAl合金組織の破壊の起点となる特定の晶析出物、Mg2S
i およびAl-Fe-Si-Mn 、Al-Fe-Si-Cr 、Al-Fe-Si-Zr 等
のAl-Fe-Si-(Mn、Cr、Zr) 系の晶析出物を、互いに間隔
を開けて分散させる(晶析出物の合計の面積率で規定す
る)ことにより、高い靱性を確保するものである。In these inventions, the amount of excess Si is increased, or a strengthening element such as Cu is added to enhance the strength of the forged material, and the forged material is a crystal precipitate of the cast material. Mg 2 S, a specific crystal precipitate that causes the fracture of the Al alloy structure
i and Al-Fe-Si- (Mn, Cr, Zr) -based crystal precipitates such as Al-Fe-Si-Mn, Al-Fe-Si-Cr, Al-Fe-Si-Zr, etc. High toughness is ensured by opening and dispersing (defined by the total area ratio of crystal precipitates).
【0009】しかし、前記したように、過剰Siを多くし
たり、あるいはCuのような高強度化元素を含んだ場合に
は、Al合金鍛造材の組織の、粒界腐食や応力腐食割れの
感受性が著しく高くなり、耐食性が低下するという、別
の問題が生じる。そして、この耐食性低下の問題は、構
造材としての基本的な要求特性である耐久性や信頼性に
かかわる問題として重大となる。However, as described above, when the amount of excess Si is increased or when a strengthening element such as Cu is included, the structure of the Al alloy forged material is susceptible to intergranular corrosion and stress corrosion cracking. Is significantly increased, and corrosion resistance is reduced, which causes another problem. The problem of deterioration in corrosion resistance becomes serious as a problem relating to durability and reliability, which are basic required characteristics as a structural material.
【0010】例えば、輸送機などの構造材は、基本的に
無塗装 (裸) で使用されるとともに、自動車などの輸送
機の走行乃至使用環境としても、海水や塩水を含み、氷
点下以下の低温から真夏の高温までの、厳しい塩水腐食
環境下となる。そして、これら構造材は、これら塩水腐
食環境下で、荷重乃至応力、或いは衝撃が付加された状
態で使用される。そして、これらの条件は、全て粒界腐
食や更には応力腐食割れを著しく促進する要因となる。For example, structural materials such as transportation machines are basically used unpainted (bare), and even in the running or use environment of transportation machines such as automobiles, they contain seawater or salt water, and have low temperatures below freezing. It is exposed to severe salt water corrosive environment from to high temperature in midsummer. Then, these structural materials are used in a state in which a load, a stress, or an impact is applied under these salt water corrosive environments. All of these conditions are factors that significantly promote intergranular corrosion and further stress corrosion cracking.
【0011】更に、輸送機などの構造材では、構成がAl
合金鍛造材だけではなく、Al合金よりも貴な鋼などの他
の金属材料と組み合わせたり、接合されて用いられるこ
とも多い。そして、このように、Al合金鍛造材がAl合金
よりも貴な他の金属材料と接合されて、かつ腐食環境下
で、荷重乃至応力、或いは衝撃が付加された状態で使用
される場合には、粒界腐食や、更には応力腐食割れを、
非常に生じやすい使用環境となっている。Further, in structural materials such as transport aircraft, the structure is Al
In addition to alloy forgings, it is often used by combining or joining with other metal materials such as steel, which is more precious than Al alloy. And, in this way, when the Al alloy forged material is joined to another metal material which is more noble than the Al alloy, and is used in a corrosive environment, under load or stress, or with a shock applied, Intergranular corrosion and even stress corrosion cracking,
The usage environment is very likely to occur.
【0012】この応力腐食割れなどに対し、本発明者ら
は、また、特願平11-285372 号によって、前記本発明者
らの発明を、更に、Cu:0.25%以下、Mn:0.05%以下、Fe:
0.30%以下、水素:0.25 cc/100g Al以下に各々規制し、
また、粒界上に存在するMg2SiやAl-Fe-Si-(Mn、Cr、Zr)
系の晶析出物 (晶出物や析出物) の平均粒径を1.2 μm
以下とするとともに、これら晶析出物同士の平均間隔
を3.0 μm 以上とした、耐食性に優れた高強度高靱性Al
合金鍛造材を提案した。Against this stress corrosion cracking, the present inventors have further described the invention of the present inventors according to Japanese Patent Application No. 11-285372, in which Cu: 0.25% or less and Mn: 0.05% or less. , Fe:
Restricted to 0.30% or less, hydrogen: 0.25 cc / 100g Al or less,
In addition, Mg 2 Si and Al-Fe-Si- (Mn, Cr, Zr) existing on grain boundaries
The average particle size of the system crystal deposits (crystallized substances and precipitates) is 1.2 μm.
In addition to the following, the average distance between these crystal precipitates was 3.0 μm or more, and high strength and high toughness Al with excellent corrosion resistance
An alloy forging was proposed.
【0013】この特願平11-285372 号では、前記特開平
06-256880 号公報のような、鋳塊の晶析出物の平均粒径
を小さくするだけではなく、晶析出物を間隔を開けて分
散しさせる形態制御によって、靱性の向上と、粒界腐食
や応力腐食割れを向上させている。This Japanese Patent Application No. 11-285372 discloses the above-mentioned Japanese Patent Application Laid-Open No.
In addition to reducing the average grain size of the crystalline precipitates in the ingot as in JP-A No. 06-256880, by controlling the morphology to disperse the crystalline precipitates at intervals, improvement of toughness and intergranular corrosion and Improves stress corrosion cracking.
【0014】[0014]
【発明が解決しようとする課題】しかし、これら提案の
耐食性に優れた高強度高靱性Al合金鍛造材であっても、
前記厳しい腐食環境下では、使用中の鍛造材の特定部位
に特に応力腐食割れが発生しやすいことを本発明者らは
知見した。However, even with these proposed high strength and high toughness Al alloy forgings excellent in corrosion resistance,
The present inventors have found that under the severe corrosive environment, stress corrosion cracking is particularly likely to occur at a specific portion of the forged material in use.
【0015】この鍛造材の特定部位とは、図1 に示す、
時効処理後のAl合金鍛造材1 の、製品2 とフラッシュ3
との切断面5aの部位である。The specific portion of the forged material is shown in FIG.
Product 2 and flash 3 of Al alloy forging 1 after aging treatment
This is a part of the cut surface 5a.
【0016】図2 に示すように、Al合金鍛造材1 は、通
常、金型鍛造における上型7 と下型8 の金型によって、
両金型の境界にできる境界面 (分割する面) である型割
り面4(パーティングラインとも言う) と、上型7 と下型
8 の金型との隙間から余分なAl合金を鍛造中に排出する
空間であるガッタ9 と、フラッシュスタンドと称される
一定の隙間10を設けて鍛造される。このようにして鍛造
されたAl合金鍛造材1には、上記ガッタ9 内に、必然的
に、フラッシュと称されるバリ3 が生じる。このフラッ
シュ3 は、鍛造後、トリムライン (フラッシュ切断線)5
において、製品2 と分離切断される。As shown in FIG. 2, the Al alloy forged material 1 is usually manufactured by the upper die 7 and the lower die 8 in die forging.
Die split surface 4 (also called parting line), which is the boundary surface (divided surface) that can be the boundary between both molds, upper mold 7 and lower mold
It is forged with a gutter 9 which is a space for discharging excess Al alloy from the gap between the die 8 and the die during forging, and a fixed gap 10 called a flash stand. In the Al alloy forged material 1 forged in this way, burrs 3 called flash are inevitably formed in the gutter 9. This flash 3 is forged and then trim line (flash cutting line) 5
At, separated from product 2.
【0017】しかして、本発明者らは、このフラッシュ
切断線5 上にある、製品とフラッシュとの (型割り面4
に対し垂直な) 切断面5aやその近傍が、使用中のAl合金
鍛造材製品2 における外表面となって、かつ、使用中
に、型割り面4 に対し垂直な方向 (切断面5aの方向) に
引張応力が付加される場合、特に応力腐食割れが発生し
やすいことを知見した。Therefore, the inventors of the present invention have found that on the flash cutting line 5 the (molding surface 4
The cut surface 5a and its vicinity are the outer surface of the Al alloy forged product 2 in use, and the direction perpendicular to the split surface 4 during use (the direction of the cut surface 5a). It was found that stress corrosion cracking is particularly likely to occur when a tensile stress is applied to ().
【0018】図1 に示すように、Al合金鍛造材1 の製品
2 の各メタルフロー (鍛流線)6は、メタルフロー6 同士
の間隔が狭くなって、そのままフラッシュ3 内に流入し
ている。しかし、鍛造工程において、鍛造素材である鋳
造材の均質化熱処理や熱間鍛造などの条件によっては、
前記製品とフラッシュとの切断面5aやその近傍の部分の
結晶粒が粗大化する場合がある。そして、この切断面5a
やその近傍の部分の結晶粒粗大化が生じた場合であっ
て、前記切断面5aやその近傍が使用中に外表面となった
り、前記引張応力が付加される場合には、前記した厳し
い腐食環境との相乗効果で、この部分に応力腐食割れが
発生する可能性が高くなる。As shown in FIG. 1, a product of Al alloy forging 1
In each metal flow (grain flow line) 6 of 2, the space between the metal flows 6 is narrowed and flows into the flash 3 as it is. However, in the forging process, depending on the conditions such as homogenizing heat treatment and hot forging of the casting material that is the forging material,
The crystal grains in the cut surface 5a between the product and the flash or in the vicinity thereof may become coarse. And this cut surface 5a
In the case where crystal grain coarsening occurs in a portion in the vicinity thereof or in the vicinity thereof, or the cutting surface 5a or the vicinity thereof becomes an outer surface during use, or when the tensile stress is added, the severe corrosion described above is performed. Due to the synergistic effect with the environment, there is a high possibility that stress corrosion cracking will occur in this part.
【0019】この様な事情に鑑み、本発明の目的は、前
記厳しい使用環境下や腐食環境下にあっても、前記製品
とフラッシュとの切断面の部分やその近傍に、応力腐食
割れが生じず、かつ高強度、高靱性であるAl合金鍛造材
および鍛造材用素材を提供しようとするものである。In view of such circumstances, an object of the present invention is to cause stress corrosion cracking at or near the cut surface between the product and the flash even under the severe operating environment or corrosive environment. The present invention is intended to provide an Al alloy forged material and a material for forged material which are high in strength and toughness.
【0020】[0020]
【課題を解決するための手段】この目的を達成するため
に、本発明Al合金鍛造材の要旨は、Mg:0.6〜1.8%、Si:
0.4〜1.8%を含み、更に、Mn:0.01 〜0.6%、Cr:0.1〜0.2
%およびZr:0.1〜0.2%の一種または二種以上を含み、残
部Alおよび不可避的不純物からなるアルミニウム合金鍛
造材であって、人工時効処理後のアルミニウム合金鍛造
材の、0.2%耐力が300MPa以上およびシャルピー衝撃値が
10J/cm2 以上であり、更に、製品とフラッシュとの切断
面の組織における、型割り面に垂直な方向の結晶粒径で
あって、この結晶粒径の内の最大のものが400 μm 以下
であることとする。In order to achieve this object, the gist of the Al alloy forged material of the present invention is Mg: 0.6 to 1.8%, Si:
0.4-1.8%, Mn: 0.01-0.6%, Cr: 0.1-0.2
% And Zr: 0.1-0.2% of one or more, an aluminum alloy forged material consisting of the balance Al and unavoidable impurities, the aluminum alloy forged material after artificial aging treatment, 0.2% proof stress is 300 MPa or more And Charpy impact value
10 J / cm 2 or more, and the crystal grain size in the direction perpendicular to the parting plane in the structure of the cut surface between the product and the flash, and the maximum grain size is 400 μm or less. It will be.
【0021】本発明のAl合金鍛造材の組織規定は、鋳造
材のデンドライト二次アーム間隔などの組織規定を除
き、全て、人工時効処理後のAl合金鍛造材組織について
規定している。The microstructure of the Al alloy forged material of the present invention is all about the microstructure of the Al alloy forged material after the artificial aging treatment except for the microstructure specification such as the dendrite secondary arm interval of the cast material.
【0022】本発明で言うAl合金鍛造材の製品とフラッ
シュとの切断面とは、前記した通り、図1 や後述する図
4 に示すAl合金鍛造材1 の、製品2 とフラッシュ3 との
切断線5 に沿った、切断面部位5aである。そして、この
切断面5aの組織における型割り面に垂直な方向(ST 方
向) の結晶粒径とは、型割り面に垂直な方向の結晶粒径
であり、垂直な切断線5 の方向に沿った垂直方向の結晶
粒径である。そして、この切断面5aの組織において、種
々の大きさを有する結晶粒径の内で、最大の粒径の結晶
のものが400 μm 以下、好ましくは200 μm 以下である
と本発明では規定する。As described above, the cut surface of the product of the Al alloy forged material and the flash referred to in the present invention is as shown in FIG.
A cut surface portion 5a of the Al alloy forged material 1 shown in 4 along a cutting line 5 between the product 2 and the flash 3. The crystal grain size in the direction perpendicular to the parting plane (ST direction) in the structure of the cut surface 5a is the crystal grain size in the direction perpendicular to the parting plane, and is along the direction of the vertical cutting line 5. The vertical grain size. Further, in the structure of the cut surface 5a, among the crystal grain sizes having various sizes, the crystal grain having the maximum grain size is 400 μm or less, preferably 200 μm or less in the present invention.
【0023】そして、この切断面5aの組織における、型
割り面に垂直な方向の結晶粒径は、切断面5aのエッチン
グによって、結晶の粒界が鮮明化するため、目視あるい
は顕微鏡観察によって、粒径の測定および評価が可能で
ある。In the texture of the cut surface 5a, the crystal grain size in the direction perpendicular to the mold splitting surface, the grain boundary of the crystal becomes clear by the etching of the cut surface 5a. It is possible to measure and evaluate the diameter.
【0024】本発明者らは、この切断面5a部分の型割り
面に垂直な方向の結晶粒径が、前記厳しい腐食環境や使
用環境における、この切断面5a部分の耐応力腐食割れ性
を支配する主要な因子であることを知見した。したがっ
て、本発明では、前記した応力腐食割れの原因となる結
晶粒粗大化を、この切断面5a部分の前記型割り面に垂直
な方向の結晶粒径で評価し、この結晶粒径を微細化する
ことによって、前記厳しい腐食環境や使用環境における
応力腐食割れを防止する。The inventors of the present invention have found that the crystal grain size of the cut surface 5a in the direction perpendicular to the parting plane governs the stress corrosion cracking resistance of the cut surface 5a in the severe corrosive environment or use environment. It was found to be a major factor that Therefore, in the present invention, the crystal grain coarsening that causes the stress corrosion cracking described above is evaluated by the crystal grain size in the direction perpendicular to the parting plane of the cut surface 5a portion, and the crystal grain size is refined. By doing so, stress corrosion cracking in the severe corrosive environment or use environment is prevented.
【0025】本発明者らは、また、この切断面5a部分の
型割り面に垂直な方向の結晶粒径が鍛造 (製造) 工程中
に、耐応力腐食割れ性の限界を越えて粗大化し易いこ
と、そして、耐応力腐食割れ性に対して限界である前記
最大結晶粒径が400 μm であることを合わせて知見し
た。The present inventors have also found that the crystal grain size of the cut surface 5a in the direction perpendicular to the parting plane easily exceeds the limit of stress corrosion cracking resistance during the forging (manufacturing) process, and coarsens easily. It was also found that the maximum crystal grain size, which is the limit for stress corrosion cracking resistance, is 400 μm.
【0026】そして、本発明では、前記輸送機などの鍛
造材用途から基本的に要求される強度と靱性とを確保す
るために、人工時効処理後のアルミニウム合金鍛造材
の、0.2%耐力 (σ0.2)を300MPa以上およびシャルピー衝
撃値を10J/cm2 以上とする。In the present invention, in order to secure the strength and toughness basically required for the use of forged materials such as the above-mentioned transport machines, the 0.2% proof stress (σ) of the aluminum alloy forged material after the artificial aging treatment is 0.2 ) to 300 MPa or more and Charpy impact value to 10 J / cm 2 or more.
【0027】前記鍛造工程中における切断面5a部分の型
割り面に垂直な方向の結晶粒径 (以下、単に、切断面の
結晶粒径と言う) の粗大化を防止して、前記範囲に微細
化させるためには、熱間鍛造前の均質化熱処理において
生じる、後述する分散粒子の結晶粒内での存在状態も重
要となる。即ち、前記切断面の結晶粒径の粗大化防止
と、前記最大結晶粒径を400 μm 以下の範囲に微細化さ
せるために、結晶粒内に微細な前記分散粒子を比較的多
数分散存在させることが好ましい。During the forging step, coarsening of the crystal grain size (hereinafter, simply referred to as the crystal grain size of the cut surface) of the cut surface 5a in the direction perpendicular to the mold splitting surface is prevented, and the crystal grain size is fine within the above range. In order to achieve this, the state of existence of dispersed particles, which will be described later, in the crystal grains, which occurs in the homogenizing heat treatment before hot forging, is also important. That is, in order to prevent coarsening of the crystal grain size of the cut surface and to refine the maximum crystal grain size to a range of 400 μm or less, a relatively large number of fine dispersed particles are present in the crystal grains. Is preferred.
【0028】より具体的には、前記請求項4 のように、
前記鍛造材組織の、結晶粒界上に存在するAl-Fe-Si-(M
n、Cr、Zr) 系などの晶析出物の平均粒径を1.2 μm 以
下とするとともに、これら晶析出物同士の平均間隔を3.
0 μm 以上とし、更に、結晶粒内の分散粒子の平均サイ
ズが1100オングストローム (Å) 以下であるとともに、
50オングストローム以上のサイズの分散粒子を10個/ μ
m3以上存在させることが好ましい。More specifically, as in claim 4,
In the forged material structure, Al-Fe-Si- (M
n, Cr, Zr) and other crystal precipitates have an average particle size of 1.2 μm or less, and the average spacing between these crystal precipitates is 3.
0 μm or more, further, the average size of the dispersed particles in the crystal grains is 1100 angstroms (Å) or less,
10 dispersed particles of size 50 angstroms or more / μ
It is preferable that m 3 or more is present.
【0029】そして、この請求項4 のような分散粒子の
微細分散状態とするためには、前記請求項2 に記載のよ
うに、鍛造素材であるAl合金鋳塊の均質化熱処理温度を
500〜 550℃とすることが好ましい。Then, in order to obtain the finely dispersed state of the dispersed particles as in claim 4, as described in claim 2, the homogenizing heat treatment temperature of the Al alloy ingot as a forging material is set.
The temperature is preferably 500 to 550 ° C.
【0030】また、同じく、前記請求項3 に記載のよう
に、均質化熱処理後のAl合金鋳塊の熱間鍛造開始温度を
350 〜 450℃とすることが好ましい。Similarly, as described in claim 3, the hot forging start temperature of the Al alloy ingot after the homogenizing heat treatment is set to
The temperature is preferably 350 to 450 ° C.
【0031】一方、本発明Al合金鍛造材を高靱性化させ
るために、前記請求項5 に記載した通り、デンドライト
二次アーム間隔(DAS) が30μm 以下となるように鋳造し
た鋳塊を用いることが好ましい。また、同じく、Al合金
鍛造材を高靱性化させるためには、請求項6 に記載した
通り、前記鋳塊を押出或いは圧延により加工後に鍛造す
ることも好ましい。On the other hand, in order to increase the toughness of the Al alloy forged material of the present invention, as described in claim 5, an ingot cast so that the dendrite secondary arm interval (DAS) is 30 μm or less is used. Is preferred. Similarly, in order to increase the toughness of the Al alloy forged material, as described in claim 6, it is also preferable that the ingot is extruded or rolled and then forged.
【0032】以上のような本発明Al合金鍛造材は、特に
耐応力腐食割れ性が低下しやすい、前記請求項7 に記載
のような、切断面5a部分に対しST方向に引張応力が付加
されて使用されるAl合金鍛造材や、前記請求項10に記載
のような、輸送機の構造材用であるAl合金鍛造材に好適
である。In the Al alloy forged material of the present invention as described above, the stress corrosion cracking resistance is particularly likely to be lowered, and tensile stress is applied to the cut surface 5a portion in the ST direction as described in claim 7. It is suitable for an Al alloy forged material used as described above and an Al alloy forged material for a structural material of a transportation machine as described in claim 10.
【0033】また、特に靱性が低下しやすい、前記請求
項8 に記載のような、鋳塊からの加工率が75% 未満の部
位を有したり、前記請求項9 に記載のような、切断面5a
部分のST方向の厚みが30mm以上であるようなAl合金鍛造
材に好適である。In addition, the toughness is liable to be lowered, and there is a portion where the processing rate from the ingot is less than 75%, as described in the above claim 8, or the cutting as described in the above claim 9. Face 5a
It is suitable for an Al alloy forged material whose thickness in the ST direction is 30 mm or more.
【0034】更に、前記請求項1乃至10の何れか1項に
記載の鍛造材用素材としての本発明請求項11の要旨は、
アルミニウム合金鋳塊からなるとともに、Mg:0.6〜1.8
%、Si:0.4〜1.8%を含み、更に、Mn:0.1〜0.6%、Cr:0.1
〜0.2%およびZr:0.1〜0.2%の一種または二種以上を含
み、残部Alおよび不可避的不純物からなり、鋳塊組織に
おけるデンドライト二次アーム間隔が30μm 以下である
こととする。Furthermore, the gist of claim 11 of the present invention as a material for forging according to any one of claims 1 to 10 is as follows:
Made of aluminum alloy ingot, Mg: 0.6 ~ 1.8
%, Si: 0.4 to 1.8%, Mn: 0.1 to 0.6%, Cr: 0.1
.About.0.2% and Zr: 0.1 to 0.2%, one or more of them, and the balance Al and unavoidable impurities, and the dendrite secondary arm spacing in the ingot structure is 30 .mu.m or less.
【0035】そして、Al合金鍛造材を高靱性化させるた
めには、請求項12に記載した通り、前記鋳塊を更に熱間
押出或いは熱間圧延により加工して鍛造材用素材とする
ことも好ましい。In order to increase the toughness of the Al alloy forged material, as described in claim 12, the ingot may be further processed by hot extrusion or hot rolling to obtain a material for forging material. preferable.
【0036】[0036]
【発明の実施の形態】本発明では、高強度高靱性化した
Al合金鍛造材の、前記腐食環境下での使用であっても、
粒界腐食感受性を低く抑制するために、Al合金組成を規
定すると同時に、Al合金鍛造材組織の内、製品とフラッ
シュとの切断面の組織における型割り面に垂直な方向の
結晶粒径であって、この結晶粒径の内の最大のものの大
きさを400 μm 以下、好ましくは200 μm 以下に規制す
る。BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, high strength and high toughness are obtained.
Al forged material, even when used in the corrosive environment,
In order to suppress the intergranular corrosion susceptibility to a low level, at the same time as defining the Al alloy composition, it is the grain size of the Al alloy forged material structure in the direction perpendicular to the mold splitting surface in the structure of the cut surface between the product and the flash. Then, the maximum size of these crystal grain sizes is restricted to 400 μm or less, preferably 200 μm or less.
【0037】(製品とフラッシュとの切断面組織におけ
る型割り面に垂直な方向の結晶粒径)先ず、本発明Al合
金鍛造材の、製品とフラッシュとの切断面の組織におけ
る型割り面に垂直な方向の結晶粒径、および、この結晶
粒径を微細に制御するために好ましい結晶粒内での分散
粒子の分布状態を以下に説明する。(Crystal grain size in the direction perpendicular to the parting plane in the cut surface structure of the product and the flash) First, in the Al alloy forged material of the present invention, perpendicular to the parting surface in the structure of the cut surface of the product and the flash. The crystal grain size in different directions and the distribution state of dispersed particles within the crystal grain that is preferable for finely controlling the crystal grain size will be described below.
【0038】なお、鍛造材の部位の中でも、最も結晶粒
が粗大化しやすい、製品とフラッシュとの切断面の組織
における型割り面に垂直な方向の最大結晶粒径( 以下、
単に、切断面の最大結晶粒径と言う) を、本発明で規定
する400 μm 以下、好ましくは200 μm 以下の範囲とす
れば、鍛造材の他の部位においても、必然的に本発明で
規定する範囲となる。逆に、鍛造材の他の部位の型割り
面に垂直な方向の最大結晶粒径を400 μm 以下の範囲と
しても、切断面の最大結晶粒径が400 μm 以下となる保
証は無い。むしろ、前記した従来技術の課題から、鍛造
材の他の部位を前記本発明範囲内としても、切断面の最
大結晶粒径の方が前記本発明範囲から外れる可能性が高
い。Among the forged parts, the maximum crystal grain size in the direction perpendicular to the parting plane in the structure of the cut surface between the product and the flash (hereinafter,
(Simply referred to as the maximum crystal grain size of the cut surface) is 400 μm or less, preferably 200 μm or less specified in the present invention, and other parts of the forged material are necessarily specified in the present invention. It becomes the range to do. On the contrary, even if the maximum grain size of the other part of the forged material in the direction perpendicular to the parting plane is 400 μm or less, there is no guarantee that the maximum grain size of the cut surface will be 400 μm or less. Rather, from the above-mentioned problems of the prior art, even if other parts of the forged material are within the range of the present invention, the maximum crystal grain size of the cut surface is likely to deviate from the range of the present invention.
【0039】本発明では、Al合金鍛造材の切断面の最大
結晶粒径を400 μm 以下とする。この切断面の最大結晶
粒径が400 μm を越えた場合、より厳しくは200 μm を
越えた場合、鍛造材の切断面における耐応力腐食割れ性
が著し低下する。In the present invention, the maximum crystal grain size of the cut surface of the Al alloy forged material is 400 μm or less. If the maximum crystal grain size of this cut surface exceeds 400 μm, or more strictly exceeds 200 μm, the stress corrosion cracking resistance of the cut surface of the forged material is markedly reduced.
【0040】この切断面の最大結晶粒径は、前記した通
り、切断面の化学エッチングによって、結晶の粒界を鮮
明化させ、5 〜400 倍の投影機および光学顕微鏡によっ
て、材質のバラツキを考慮するため、各Al合金鍛造材毎
に1 視野、20個のロッドのAl合金鍛造材の20視野観察に
よって行う。そして評価は、これら鍛造製品ごとの切断
面の観察結果の最大値によって行う。なお、結晶粒界の
判別が困難な場合は、切断面を電解エッチング後、5 〜
400 倍の偏光顕微鏡を用いて測定する。As described above, the maximum crystal grain size of the cut surface is to clarify the grain boundaries of the crystal by the chemical etching of the cut surface, and the variation of the material is taken into consideration by the projector of 5 to 400 times and the optical microscope. In order to do so, 1 field of view for each Al alloy forging, and 20 fields of view of the Al alloy forging of 20 rods. The evaluation is performed by the maximum value of the observation results of the cut surface of each of these forged products. If it is difficult to identify the crystal grain boundaries, after electrolytically etching the cut surface,
Measure with a 400x polarizing microscope.
【0041】(結晶粒内分散粒子)そして、鍛造工程中に
おける切断面の最大結晶粒径の粗大化を防止して、400
μm 以下と微細化させるために、熱間鍛造前の均質化熱
処理において生じる分散粒子を結晶粒内において微細分
布させる。化合物名は後述する、これら分散粒子は、亜
結晶粒化ならびに再結晶後の粒界移動を妨げる (ピン止
め) 効果があるため、Al合金鍛造材の組織、特に切断面
の結晶粒を微細な結晶粒や亜結晶粒とすることができ
る。(Dispersed particles in crystal grains) Then, the coarsening of the maximum crystal grain size of the cut surface during the forging process is prevented, and
In order to reduce the size to less than μm, the dispersed particles generated in the homogenizing heat treatment before hot forging are finely distributed in the crystal grains. The compound name will be described later.Since these dispersed particles have an effect of hindering grain boundary movement after subcrystallization and recrystallization (pinning), the microstructure of the Al alloy forged material, especially the crystal grains on the cut surface, is made fine. It can be a crystal grain or a sub-crystal grain.
【0042】この分散粒子による前記切断面の結晶粒の
粗大化防止効果発揮には、結晶粒内の分散粒子の平均サ
イズが1100オングストローム (Å) 以下であるととも
に、50オングストローム以上のサイズの分散粒子を10個
/ μm3以上の密度で存在させることが好ましい。分散粒
子自体が粗大化したり、分散粒子自体の数が不足して、
前記規定を満足しない場合、前記結晶粒微細化効果が得
られず、切断面の結晶粒が粗大化してしまう可能性があ
る。なお、分散粒子のサイズ (大きさ) は一個の分散粒
子の最大の長さとし、前記分散粒子の平均サイズも50オ
ングストローム以上のサイズの分散粒子の平均サイズと
する。In order to exert the effect of preventing the coarsening of the crystal grains on the cut surface by the dispersed particles, the average size of the dispersed particles in the crystal grains is 1100 angstroms (Å) or less and the dispersed particles having a size of 50 angstroms or more. 10 pieces
It is preferable that the particles are present at a density of / μm 3 or more. The dispersed particles themselves become coarse, or the number of dispersed particles themselves is insufficient,
If the above requirements are not satisfied, the effect of refining the crystal grains may not be obtained, and the crystal grains on the cut surface may become coarse. The size (size) of the dispersed particles is the maximum length of one dispersed particle, and the average size of the dispersed particles is also the average size of dispersed particles having a size of 50 angstroms or more.
【0043】この分散粒子の結晶粒内における大きさと
密度の測定は、前記切断面の組織を、5000〜20000 倍程
度の透過型電子顕微鏡(TEM) により観察し、材質のバラ
ツキを考慮するため、各Al合金鍛造材毎に2 視野、10個
のロッドのAl合金鍛造材の20視野観察によって行う。こ
こにおいて、本発明で言う分散粒子の結晶粒内における
大きさとは分散粒子の最大長さとする。また、密度と
は、前記20視野の合計体積での分布を単位体積(1μm3)
当たりに換算したものである。The size and density of the dispersed particles in the crystal grains are measured by observing the structure of the cut surface with a transmission electron microscope (TEM) of about 5,000 to 20,000 times, and considering variations in materials, Two visual fields for each Al alloy forging, and 20 visual fields for observing the Al alloy forging of 10 rods. Here, the size of the dispersed particles in the crystal grains referred to in the present invention is the maximum length of the dispersed particles. The density means the distribution in the total volume of the 20 fields of view as a unit volume (1 μm 3 )
It is converted into per hit.
【0044】Al合金鍛造材の前記切断面5aの組織におけ
る分散粒子の結晶粒内における分布状況を図6 と図7 に
示す。図6 (a) 、(b) は前記切断面の組織の20000 倍の
TEMによる組織写真 (写真を映して図面化したもの) で
あり、結晶粒内における黒点で示される分散粒子の分布
状況を示す。6 and 7 show the distribution of dispersed particles in the crystal grains in the texture of the cut surface 5a of the Al alloy forged material. Figures 6 (a) and 6 (b) show 20,000 times the texture of the cut surface.
Fig. 3 is a TEM micrograph (photographed from a photograph) showing the distribution of dispersed particles represented by black dots in crystal grains.
【0045】図6 (a) は後述する実施例のAl合金鍛造材
(図3)および表2 の比較例9 の切断面5aの組織であり、
比較的分散粒子の平均サイズが比較的大きく、かつ個数
が比較的少ない。一方、前記図6(b)のAl合金鍛造材の切
断面5aの組織は、後述する実施例表2 の発明例6 であ
り、比較的分散粒子の平均サイズが比較的小さくかつ個
数が比較的多い (密度が高い) 。FIG. 6 (a) is an Al alloy forged material of an example described later.
(Fig. 3) and the structure of the cut surface 5a of Comparative Example 9 in Table 2,
The average size of dispersed particles is relatively large, and the number of dispersed particles is relatively small. On the other hand, the structure of the cut surface 5a of the Al alloy forged material of FIG. 6 (b) is Invention Example 6 of Example Table 2 described later, in which the average size of the dispersed particles is relatively small and the number thereof is relatively small. Many (high density).
【0046】(粒界上の晶析出物)次に、本発明Al合金鍛
造材組織の粒界上の晶析出物の平均粒径と平均間隔につ
いて以下に説明する。本発明では、人工時効処理後のAl
合金鍛造材の靱性を向上させ、0.2%耐力 (σ0.2)が300M
Pa以上およびシャルピー衝撃値が10J/cm2 以上を確保す
るために、および耐応力腐食割れ性の向上のために、Al
合金鍛造材の粒界上の晶析出物の平均粒径と平均間隔に
ついて、好ましい範囲を規定する。即ち、Al合金鍛造材
の、粒界上に存在するMg2Si やAl-Fe-Si系金属間化合
物、単体Siなどの晶析出物 (晶出物や析出物) の平均粒
径を1.2 μm 以下とするとともに、これら晶析出物同士
の平均間隔を3.0 μm 以上とすることが好ましい。(Crystal Deposits on Grain Boundaries) Next, the average grain size and the average interval of the crystal deposits on the grain boundaries of the Al alloy forged material structure of the present invention will be described below. In the present invention, Al after artificial aging treatment
Improves the toughness of alloy forgings and has a 0.2% proof stress (σ 0.2 ) of 300M.
In order to secure Pa or more and Charpy impact value of 10 J / cm 2 or more, and to improve stress corrosion cracking resistance, Al
A preferable range is defined for the average grain size and the average spacing of the crystal precipitates on the grain boundaries of the alloy forging material. That is, the average grain size of crystal precipitates (crystallized substances or precipitates) such as Mg 2 Si, Al-Fe-Si-based intermetallic compounds and simple substance Si existing on the grain boundaries of the Al alloy forged material is 1.2 μm. In addition to the following, it is preferable that the average distance between these crystal precipitates is 3.0 μm or more.
【0047】これら粒界上の晶析出物同士の平均間隔が
3.0 μm 未満の場合、例えば、前記特開平06-256880 号
公報のような晶析出物の平均粒径を小さくするだけの形
態制御では、たとえ晶析出物の平均粒径が1.2 μm 以下
と小さくても、互いの間隔が小さく密集した状態乃至つ
ながった状態となり、前記靱性や疲労特性および耐応力
腐食割れ性を向上させることができない。The average spacing between the crystal precipitates on these grain boundaries is
When it is less than 3.0 μm, for example, in the morphology control such as the above-mentioned JP-A-06-256880, which only reduces the average particle size of the crystal precipitate, the average particle size of the crystal precipitate is as small as 1.2 μm or less. However, since the distance between them is small and they are in a dense state or a connected state, the toughness, fatigue characteristics and stress corrosion cracking resistance cannot be improved.
【0048】また、晶析出物同士の間隔を3.0 μm 以上
としても、晶析出物の平均粒径が1.2 μm を越える場
合、結果として、晶析出物が密集した状態乃至つながっ
た状態となり、前記靱性や疲労特性および耐応力腐食割
れ性を向上させることができない。Even if the distance between the crystal precipitates is 3.0 μm or more, when the average particle size of the crystal precipitates exceeds 1.2 μm, as a result, the crystal precipitates are in a dense state or a connected state, and the toughness is And fatigue characteristics and stress corrosion cracking resistance cannot be improved.
【0049】即ち、晶析出物が粒界上に密に存在すると
靱性や疲労特性等の機械的特性を劣化させる。また、こ
れら晶析出物自身および周囲が、鍛造材の使用中に前記
腐食環境下で溶出するため、応力腐食割れを生じやすく
なる。これに対し、晶析出物の平均粒径が大きくても、
それが間隔を開けて分散している (まばらに存在する)
ならば、晶析出物を起点とする亀裂の連結が生じにくく
なり、靱性や疲労特性の向上に寄与し、更に前記腐食環
境下で各々の晶析出物自身および周囲の溶出による腐食
面の連結が生じにくくなる。That is, if the crystal precipitates are densely present on the grain boundaries, mechanical properties such as toughness and fatigue properties are deteriorated. Further, since these crystal precipitates themselves and their surroundings are eluted under the corrosive environment during use of the forged material, stress corrosion cracking is likely to occur. On the other hand, even if the average particle size of the crystal precipitate is large,
It is spaced and dispersed (sparsely present)
If so, the connection of cracks originating from the crystal precipitates is less likely to occur, contributes to the improvement of toughness and fatigue properties, and further, the connection of the corrosion surface due to the dissolution of each crystal precipitate itself and the surroundings under the corrosive environment. Less likely to occur.
【0050】なお、実際のAl合金鍛造材では、メカニカ
ル鍛造などの熱間鍛造によっても、鍛造材部品の大きさ
や形状、厚み、或いは部品の部位によっては、加工率が
低くなる場合がある。例えば、自動車用のサスペンショ
ン部品としてのアーム類のような形状の場合、50% 程度
の低い加工率にしかならない場合がある。そして、この
加工率が低い部位では、鍛造されても鋳造組織が残るた
めに、加工率が高い他の部位に比して、特に靱性や疲労
特性は、必然的に低くなる傾向にある。In an actual Al alloy forged material, the working ratio may be lowered even by hot forging such as mechanical forging, depending on the size, shape and thickness of the forged material part or the part part. For example, in the case of arms such as suspension parts for automobiles, the machining rate may be as low as about 50%. In addition, since the cast structure remains in the portion having a low processing rate even if it is forged, the toughness and fatigue characteristics tend to be inevitably lower than those in other portions having a high processing rate.
【0051】このような特に靱性や疲労特性が低下しや
すい、鋳塊からの加工率が75% 未満の部位を有したり、
前記切断面のST方向の厚みが30mm以上であるようなAl合
金鍛造材の場合に、特に、本発明の粒界上に存在する晶
析出物の平均粒径と晶析出物同士の平均間隔の制御は、
高靱性、高疲労特性化させるために好適である。In particular, there is a portion where the workability from the ingot is less than 75%, in which the toughness and fatigue characteristics are likely to decrease,
In the case of an Al alloy forged material such that the thickness of the cut surface in the ST direction is 30 mm or more, in particular, the average grain size of the crystal precipitates and the average spacing between the crystal precipitates present on the grain boundaries of the present invention. Control is
It is suitable for achieving high toughness and high fatigue characteristics.
【0052】そして、この晶析出物の大きさ制御と、晶
析出物が互いに間隔を開けて分布している(晶析出物の
互いの間隔が小さく密集した状態乃至つながった状態で
はない)状況に良く対応する指標として、本発明では、
晶析出物の平均粒径と、該晶析出物間の平均間隔を選択
する。以上の晶析出物制御の部分は、特願平11-285372
号と同じ内容である。Then, the size control of the crystal precipitates and the situation in which the crystal precipitates are distributed with an interval between each other (the intervals between the crystal precipitates are small and not close to each other or not connected to each other) As an index that corresponds well, in the present invention,
The average particle size of the crystal precipitates and the average spacing between the crystal precipitates are selected. The above-mentioned part for controlling crystal precipitates is described in Japanese Patent Application No. 11-285372.
It has the same content as the issue.
【0053】これら晶析出物の平均粒径と、晶析出物間
の平均間隔の測定は、Al合金鍛造材の組織を、400 倍程
度の光学顕微鏡または500 倍程度の走査型電子顕微鏡(S
EM)により、材質のバラツキを考慮するため、Al合金鍛
造材毎に前記切断面の1 箇所づつ、Al合金鍛造材20個
(20視野) について、測定した目視観察乃至画像解析結
果の平均によって行う。The average grain size of these crystal precipitates and the average spacing between the crystal precipitates were measured by observing the structure of the Al alloy forged material with an optical microscope of about 400 times or a scanning electron microscope (S) of about 500 times.
EM), in order to take into account variations in material, one for each of the Al alloy forgings, one place on the cut surface, 20 Al alloy forgings
(20 fields of view) is measured by visual observation or average of image analysis results.
【0054】ここにおいて、本発明で言う粒界上の晶析
出物の平均粒径とは、前記各視野の粒界上で測定でき
る、粒界上に存在する前記晶析出物粒子の平均の長さを
言い、前記各視野で測定される平均の長さを、前記20視
野で平均値化したものとする。Here, the average grain size of the crystal precipitates on the grain boundaries referred to in the present invention means the average length of the crystal deposit particles existing on the grain boundaries, which can be measured on the grain boundaries of the respective visual fields. That is, the average length measured in each of the visual fields is averaged in the 20 visual fields.
【0055】また、本発明で言う晶析出物間の間隔と
は、各視野で測定される粒界の長さを、各視野の粒界上
に観察される晶析出物粒子の数で除した値を、前記20視
野で平均値化したものとする。The interval between crystal precipitates in the present invention is the length of the grain boundary measured in each visual field divided by the number of crystal precipitate particles observed on the grain boundary in each visual field. The values are averaged in the 20 fields of view.
【0056】なお、前記腐食環境下でのAl合金鍛造材の
耐応力腐食割れ性は、粒界腐食性に一義的に対応してお
り、Al合金鍛造材の耐応力腐食割れ性を評価することが
粒界腐食感受性の評価にもつながる。The stress corrosion cracking resistance of the Al alloy forged material in the above corrosive environment uniquely corresponds to the intergranular corrosion resistance, and the stress corrosion cracking resistance of the Al alloy forged material should be evaluated. Also leads to the evaluation of intergranular corrosion susceptibility.
【0057】(Al合金鋳塊組織)次に、本発明Al合金鍛造
材用の素材としてのAl合金鋳塊組織について以下に説明
する。本発明における鍛造材用の鋳塊組織は、Al合金鍛
造材の高靱性、高疲労特性化を保証するために、鋳塊の
デンドライト二次アーム間隔(DAS) を30μm 以下とする
ことが好ましい。これにより、Al合金鋳塊およびAl合金
鍛造材の結晶粒を微細化させるとともに、特に晶出物の
合計の面積率を低くし、Al合金鍛造材の靱性を向上させ
る。この鋳塊のデンドライト二次アーム間隔(DAS) が30
μm を越えて大きくなった場合、鋳塊からの加工率 (鋳
塊を鍛造のみ行う場合や、鋳塊を押出や圧延後鍛造する
場合の全体の加工率) が70% 以下などの、加工率の低い
部位が存在した場合に、晶出物を微細化できず、Al合金
鍛造材全体の疲労特性や靱性を向上させることができな
い危険性がある。(Al alloy ingot structure) Next, the Al alloy ingot structure as a material for the Al alloy forged material of the present invention will be described below. The ingot structure for a forged material in the present invention preferably has a dendrite secondary arm spacing (DAS) of the ingot of 30 μm or less in order to ensure high toughness and high fatigue characteristics of the Al alloy forged material. This refines the crystal grains of the Al alloy ingot and the Al alloy forged material, and particularly lowers the total area ratio of the crystallized substances, and improves the toughness of the Al alloy forged material. The dendrite secondary arm spacing (DAS) of this ingot is 30
When the size exceeds μm, the processing rate from the ingot (the overall processing rate when the ingot is only forged, or when the ingot is extruded or rolled and then forged) is 70% or less. If there is a portion of low Al content, crystallized substances cannot be refined, and there is a risk that the fatigue characteristics and toughness of the entire Al alloy forged material cannot be improved.
【0058】なお、本発明の鍛造材用の素材とは、鋳塊
ままのもの、鋳塊を均質化熱処理したもの、更に鋳塊を
均質化熱処理後一旦押出加工や圧延加工したもの等を含
む。また、鋳塊乃至鍛造材用素材の形状は、丸棒などの
インゴットやスラブ形状、或いは成品形状に近いニアネ
ットシェイプ等があり、特に制限されるものではない。The material for the forging material of the present invention includes an ingot, an ingot which is homogenized and heat treated, and an ingot which is once extruded or rolled. . Further, the shape of the ingot or the material for forging material is an ingot such as a round bar, a slab shape, or a near net shape close to the shape of a product, and is not particularly limited.
【0059】次に、本発明Al合金鍛造材乃至鍛造材用の
素材における、化学成分組成について説明する。本発明
のAl合金は、自動車、船舶などの輸送機材や構造材ある
いは部品用として、高強度、高靱性および耐応力腐食割
れ性などの高い耐久性を保証する必要がある。Next, the chemical composition of the Al alloy forged material of the present invention or the material for the forged material will be described. The Al alloy of the present invention is required to ensure high strength, high toughness, and high durability such as stress corrosion cracking resistance for transportation equipment such as automobiles and ships, structural materials or parts.
【0060】したがって、本発明Al合金鍛造材の化学成
分組成は、Al-Mg-Si系のJIS 6000系Al合金の成分規格
(JIS 6101、6111、6003、6151、6061、6N01、6063など)
に相当するものとして、基本的にはMg:0.6〜1.6%、Si:
0.4〜1.8%を含み、Mn:0.1〜0.6%、Cr:0.1〜0.2%およびZ
r:0.1〜0.2%の一種または二種以上を含む。なお、各元
素量における% 表示はすべて質量% の意味である。Therefore, the chemical composition of the Al alloy forged material of the present invention is the composition standard of the Al-Mg-Si based JIS 6000 series Al alloy.
(JIS 6101, 6111, 6003, 6151, 6061, 6N01, 6063, etc.)
Basically, Mg: 0.6-1.6%, Si:
Including 0.4-1.8%, Mn: 0.1-0.6%, Cr: 0.1-0.2% and Z
r: Contains 0.1 to 0.2% of one or more kinds. In addition, all percentages in each element amount mean% by mass.
【0061】しかし、JIS 6000系Al合金の各成分規格通
りにならずとも、前記本発明の諸特性を阻害しない範囲
で、更なる特性の向上や他の特性を付加するための、他
の元素を適宜含むなどの成分組成の変更は適宜許容され
る。また、溶解原料スクラップなどから必然的に混入さ
れる不純物も、本発明鍛造材の品質を阻害しない範囲で
許容される。However, other elements for improving the characteristics or adding other characteristics are provided within the range not impairing the characteristics of the present invention, even if they do not conform to the respective component specifications of JIS 6000 series Al alloy. It is permissible to appropriately change the composition of components such as containing. Further, impurities that are inevitably mixed in from melted raw material scraps and the like are also permitted within a range that does not impair the quality of the forged material of the present invention.
【0062】次に、本発明Al合金鍛造材の各元素の含有
量について、臨界的意義や好ましい範囲について説明す
る。Next, the critical meaning and preferable range of the content of each element in the Al alloy forged material of the present invention will be described.
【0063】Mg:0.6〜1.8%。
Mgは人工時効処理により、Siとともにβ''相ならびに
β' 相として析出し、最終製品使用時の高強度 (耐力)
を付与するために必須の元素である。Mgの0.6%未満の含
有では、人工時効処理時の時効硬化量が低下する。一
方、1.8%を越えて含有されると、強度 (耐力) が高くな
りすぎ、鍛造性を阻害する。また、溶体化処理後の焼き
入れ途中に多量のMg2 Siや単体Siが析出しやすく、粒界
上に存在する晶析出物の平均粒径を1.2 μm 以下とする
とともに、これら晶析出物同士の平均間隔を3.0 μm 以
上とすることができない。したがって、Mgの含有量は0.
6 〜1.8%の範囲とする。Mg: 0.6-1.8%. Due to artificial aging treatment, Mg precipitates as β '' and β'phases with Si, resulting in high strength (proof stress) when the final product is used.
Is an essential element for imparting. If the content of Mg is less than 0.6%, the amount of age hardening during the artificial aging treatment decreases. On the other hand, when the content exceeds 1.8%, the strength (proof stress) becomes too high, which hinders the forgeability. In addition, a large amount of Mg 2 Si and simple substance Si are likely to precipitate during the quenching after the solution treatment, and the average grain size of the crystal precipitates existing on the grain boundaries is set to 1.2 μm or less, and these crystal precipitates are It is impossible to set the average interval of over 3.0 μm. Therefore, the content of Mg is 0.
The range is 6 to 1.8%.
【0064】Si:0.4〜1.8%。
SiもMgとともに、人工時効処理により、β''相ならびに
β' 相として析出して、最終製品使用時の高強度 (耐
力) を付与するために必須の元素である。Siの0.4%未満
の含有では人工時効処理で十分な強度が得られない。一
方、1.8%を越えて含有されると、鋳造時および溶体化処
理後の焼き入れ途中で、粗大な単体Si粒子が晶出および
析出して、前記した通り、耐食性と靱性を低下させる。
また、過剰Siが多くなって、粒界上に存在する晶析出物
の平均粒径を1.2 μm 以下とするとともに、これら晶析
出物同士の平均間隔を3.0 μm 以上とすることができ
ず、高耐食性と高靱性、高疲労特性を得ることができな
い。更に伸びが低くなるなど、加工性も阻害する。した
がって、Siの含有量は0.4 〜1.8%の範囲とし、この範囲
の中でも、Mg含有量との関係で、できるだけ過剰Siは少
なくすることが好ましい。Si: 0.4 to 1.8%. Si, together with Mg, is an essential element for precipitating as β ″ phase and β ′ phase by artificial aging treatment and imparting high strength (proof stress) when the final product is used. If the Si content is less than 0.4%, sufficient strength cannot be obtained by artificial aging treatment. On the other hand, if the content exceeds 1.8%, coarse single Si particles crystallize and precipitate during casting and during quenching after solution treatment, and as described above, the corrosion resistance and toughness deteriorate.
In addition, the excess Si increases, the average grain size of the crystal precipitates existing on the grain boundaries is 1.2 μm or less, and the average spacing between these crystal precipitates cannot be 3.0 μm or more. Corrosion resistance, high toughness, and high fatigue properties cannot be obtained. Workability is also hindered, for example, elongation is reduced. Therefore, the Si content is set in the range of 0.4 to 1.8%, and in this range, it is preferable to reduce the excess Si as much as possible in relation to the Mg content.
【0065】Mn:0.01 〜0.6%、Cr:0.1〜0.2%およびZr:
0.1〜0.2%の一種または二種以上。
これらの元素は均質化熱処理時およびその後の熱間鍛造
時に、Fe、Mn、Cr、Zr、Si、Alなどがその含有量に応じ
て選択的に結合したAl-Mn 系、Al-Cr 系、Al-Zr 系金属
間化合物であり、(Fe 、Mn、Cr)3SiAl12、Al3Zr 、(AlS
i)3Zr に代表される分散粒子 (分散相) を生成する。Mn: 0.01-0.6%, Cr: 0.1-0.2% and Zr:
0.1 to 0.2% of one or more kinds. Fe, Mn, Cr, Zr, Si, Al, etc. are selectively combined according to their contents during homogenizing heat treatment and subsequent hot forging.Al-Mn system, Al-Cr system, Al-Zr-based intermetallic compound, (Fe, Mn, Cr) 3 SiAl 12 , Al 3 Zr, (AlS
i) Generate dispersed particles (dispersed phase) represented by 3 Zr.
【0066】これらの分散粒子は再結晶後の粒界移動を
妨げる効果があるため、前記切断面のST方向の結晶粒の
粗大化を防止するとともに、本発明Al合金鍛造材全体に
渡って、微細な結晶粒や亜結晶粒を得ることができる。
この結果、特に前記切断面のST方向の最大結晶粒を400
μm 以下、好ましくは200 μm 以下と微細化させること
ができる。また、Mn、Cr、Zrは固溶による強度およびヤ
ング率の増大も見込める。Since these dispersed particles have an effect of hindering the movement of grain boundaries after recrystallization, they prevent coarsening of the crystal grains in the ST direction of the cut surface and, at the same time, over the entire Al alloy forged material of the present invention, It is possible to obtain fine crystal grains and sub-crystal grains.
As a result, the maximum crystal grain in the ST direction of the cut surface is 400
The size can be reduced to less than or equal to μm, preferably less than or equal to 200 μm. Further, Mn, Cr, and Zr can be expected to increase strength and Young's modulus due to solid solution.
【0067】Mn、Cr、Zrの含有量が少なすぎると、これ
らの効果が期待できず、一方、これらの元素の過剰な含
有は溶解、鋳造時に粗大な金属間化合物や晶出物を生成
しやすく、破壊の起点となり、靱性や疲労特性を低下さ
せる原因となる。このため、これらの元素は各々、Mn:
0.01 〜0.6%、Cr:0.1〜0.2%およびZr:0.1〜0.2%の範囲
で一種または二種以上含有させる。If the contents of Mn, Cr, and Zr are too small, these effects cannot be expected. On the other hand, if the contents of these elements are excessively large, coarse intermetallic compounds and crystallized substances are formed during melting and casting. It easily becomes a starting point of fracture and causes deterioration of toughness and fatigue properties. Therefore, each of these elements is Mn:
One kind or two or more kinds are contained in the range of 0.01 to 0.6%, Cr: 0.1 to 0.2% and Zr: 0.1 to 0.2%.
【0068】ただ、これらの元素の内でも、Zrは、数十
から数百オングトロームのサイズの、Al-Mn 系やAl-Cr
系の分散粒子よりも、より微細なAl-Zr 系分散粒子が析
出する。このため、特にZrは、結晶粒界や亜結晶粒界の
移動を阻止し、結晶粒の微細化、亜結晶粒化する効果が
大きく、破壊靱性や疲労特性などの向上効果が大きい。However, among these elements, Zr is Al-Mn system or Al-Cr having a size of tens to hundreds of angstroms.
Finer Al-Zr-based dispersed particles are precipitated than the dispersed particles of the system. Therefore, especially Zr has a large effect of blocking the movement of the crystal grain boundaries and the sub-crystal grain boundaries, refining the crystal grains, and sub-graining, and has a great effect of improving the fracture toughness and fatigue characteristics.
【0069】一方、Mnは晶出物を生成するため、Mnを含
有した場合、製造条件にもよるが、粒界上に存在する晶
析出物の平均粒径、晶析出物同士の平均間隔を、本発明
で規定する好ましい範囲にすることができなくなる可能
性が高くなる場合がある。したがって、Mnを含有する場
合の制御は難しく、Al合金鍛造材の高い耐応力腐食割れ
性を保証する観点からは、Mnの含有量を0.05% 以下に規
制する方が好ましい。したがって、Mn、Cr、Zrの元素の
中でも、Zrのみか、ZrおよびCrを選択的に含有させるこ
とが好ましい。On the other hand, since Mn produces crystallized substances, when Mn is contained, the average particle size of the crystal precipitates existing on the grain boundaries and the average spacing between the crystal precipitates are varied depending on the production conditions. However, there is a high possibility that the preferred range defined by the present invention cannot be achieved. Therefore, it is difficult to control when Mn is contained, and from the viewpoint of ensuring high stress corrosion cracking resistance of the Al alloy forged material, it is preferable to regulate the Mn content to 0.05% or less. Therefore, among the elements of Mn, Cr, and Zr, it is preferable to selectively contain Zr alone or Zr and Cr.
【0070】Cu:0.50%以下。
Cuは、Al合金鍛造材の組織の応力腐食割れや粒界腐食の
感受性を著しく高め、Al合金鍛造材の耐食性や耐久性を
低下させる。したがって、本発明では、この観点からCu
含有量をできるだけ少なく規制する。しかし、一方で、
Cuは固溶強化にて強度の向上に寄与する他、時効処理に
際して、最終製品の時効硬化を著しく促進する効果も有
する。なお、Cu含有量を少なくすると、高純度地金を使
用する必要があり、鋳造コストがかかる問題もある。し
たがって、Cuは0.50% 以下の含有まで許容する。Cu: 0.50% or less. Cu remarkably increases the susceptibility of the Al alloy forged material to stress corrosion cracking and intergranular corrosion, and reduces the corrosion resistance and durability of the Al alloy forged material. Therefore, in the present invention, from this viewpoint, Cu
Control the content as low as possible. But on the other hand,
Cu contributes to the improvement of strength by solid solution strengthening, and also has the effect of significantly promoting the age hardening of the final product during the aging treatment. If the Cu content is reduced, it is necessary to use a high-purity metal ingot, which causes a problem of high casting cost. Therefore, Cu is allowed up to a content of 0.50% or less.
【0071】Fe:0.40%以下。
Al合金に不純物として含まれるFeは、本発明で問題とす
る粗大な晶出物を生成する。これらの晶出物は、前記し
た通り、破壊靱性および疲労特性などを劣化させる。特
に、Feの含有量が0.40% 、より厳密には0.35% を越える
と、粒界上に存在するAl-Fe-Si-(Mn、Cr、Zr) 系晶析出
物の平均粒径、晶析出物同士の平均間隔を、本発明で規
定する好ましい範囲にすることができなくなる可能性が
高くなる。したがって、Feの含有量は0.40% 以下、より
好ましくは0.35% 以下とすることが好ましい。Fe: 0.40% or less. Fe contained as an impurity in the Al alloy forms a coarse crystallized substance, which is a problem in the present invention. As described above, these crystallized substances deteriorate the fracture toughness and fatigue properties. In particular, when the Fe content exceeds 0.40%, more strictly 0.35%, the average grain size of Al-Fe-Si- (Mn, Cr, Zr) -based crystal precipitates present on the grain boundaries There is a high possibility that the average distance between the objects cannot be set within the preferable range specified in the present invention. Therefore, the Fe content is preferably 0.40% or less, more preferably 0.35% or less.
【0072】水素:0.25 cc/100g Al以下。
水素(H2)は、特に、鍛造材の加工度が小さくなる場合、
水素に起因する気泡が鍛造等加工で圧着せず、破壊の起
点となるため、靱性や疲労特性を著しく低下させる。そ
して、高強度化した輸送機の構造材などにおいては、特
に水素による影響が大きい。したがって、水素は0.25 c
c/100g Al 以下のできるだけ少ない含有量とする。Hydrogen: 0.25 cc / 100g Al or less. Hydrogen (H 2), particularly when working ratio forging is reduced,
Since bubbles caused by hydrogen do not press-bond during forging and the like and become the starting point of fracture, the toughness and fatigue properties are significantly reduced. In addition, hydrogen has a large influence particularly on the structural material of the transportation machine having high strength. Therefore, hydrogen is 0.25 c
c / 100g Al Content should be as low as possible.
【0073】Zn、Ti、B 、Be、V 等。
Zn、Ti、B 、Be、V 等は、各々目的に応じて、選択的に
含有される元素である。
Zn:0.005〜1.0%。
Znは人工時効時において、MgZn2 を微細かつ高密度に析
出させ高い強度を実現させる。また、固溶したZnは粒内
の電位を下げ、腐食形態を粒界からではなく、全面的な
腐食として、粒界腐食や応力腐食割れを結果として軽減
する効果が期待できる。しかし、Znの0.005%未満の含有
では人工時効で十分な強度が得られず、前記耐食性の向
上効果もない。一方、1.0%を越えて含有されると、耐蝕
性が顕著に低下する。したがって、選択的に含有させる
場合のZnの含有量は0.005 〜1.0%の範囲とすることが好
ましい。Zn, Ti, B, Be, V and the like. Zn, Ti, B 2, Be, V 3 and the like are elements selectively contained according to the purpose. Zn: 0.005-1.0%. Zn precipitates MgZn 2 finely and densely during artificial aging to realize high strength. Further, solid-solubilized Zn can be expected to have the effect of lowering the potential inside the grains and reducing the intergranular corrosion and stress corrosion cracking as a result of the corrosion morphology being not the grain boundaries but the overall corrosion. However, if the content of Zn is less than 0.005%, sufficient strength cannot be obtained by artificial aging, and there is no effect of improving the corrosion resistance. On the other hand, if the content exceeds 1.0%, the corrosion resistance is significantly reduced. Therefore, when the Zn is selectively contained, the Zn content is preferably in the range of 0.005 to 1.0%.
【0074】Ti:0.001〜0.1%。
Tiは鋳塊の結晶粒を微細化し、押出、圧延、鍛造時の加
工性を向上させるために添加する元素である。しかし、
Tiの0.001%未満の含有では、加工性向上の効果が得られ
ず、一方、Tiを0.1%を越えて含有すると、粗大な晶析出
物を形成し、前記加工性を低下させる。したがって、選
択的に含有させる場合のTiの含有量は0.001 〜0.1%の範
囲とすることが好ましい。Ti: 0.001 to 0.1%. Ti is an element added for refining the crystal grains of the ingot and improving workability during extrusion, rolling and forging. But,
If the content of Ti is less than 0.001%, the effect of improving the workability cannot be obtained. On the other hand, if the content of Ti exceeds 0.1%, coarse crystal precipitates are formed and the workability is deteriorated. Therefore, when selectively contained, the Ti content is preferably in the range of 0.001 to 0.1%.
【0075】B:1 〜300ppm。
B はTiと同様、鋳塊の結晶粒を微細化し、押出、圧延、
鍛造時の加工性を向上させるために添加する元素であ
る。しかし、B の1ppm未満の含有では、この効果が得ら
れず、一方、300ppmを越えて含有されると、やはり粗大
な晶析出物を形成し、前記加工性を低下させる。したが
って、選択的に含有させる場合のB の含有量は1 〜300p
pmの範囲とすることが好ましい。B: 1 to 300 ppm. B is similar to Ti in that the crystal grains of the ingot are refined, extruded, rolled,
It is an element added to improve workability during forging. However, if the content of B 2 is less than 1 ppm, this effect cannot be obtained. On the other hand, if the content of B exceeds 300 ppm, coarse crystal precipitates are formed and the workability is deteriorated. Therefore, the content of B when selectively contained is 1 to 300p.
It is preferably in the range of pm.
【0076】Be:0.1〜100ppm。
Beは空気中におけるAl溶湯の再酸化を防止するために含
有させる元素である。しかし、0.1ppm未満の含有では、
この効果が得られず、一方、100ppmを越えて含有される
と、材料硬度が増大し、前記加工性を低下させる。した
がって、選択的に含有させる場合のBeの含有量は0.1 〜
100ppmの範囲とすることが好ましい。Be: 0.1 to 100 ppm. Be is an element contained to prevent reoxidation of the molten Al in the air. However, if the content is less than 0.1 ppm,
This effect cannot be obtained. On the other hand, if the content exceeds 100 ppm, the material hardness increases and the workability decreases. Therefore, the content of Be when selectively contained is 0.1 to
It is preferably in the range of 100 ppm.
【0077】V:0.15% 以下。
V は、Mn、Cr、Zrなどと同様に、均質化熱処理時および
その後の熱間鍛造時に、分散粒子 (分散相) を生成す
る。これらの分散粒子は再結晶後の粒界移動を妨げる効
果があるため、微細な結晶粒を得ることができる。しか
し過剰な含有は溶解、鋳造時に粗大なAl-Fe-Si-V系の金
属間化合物や晶析出物を生成しやすく、破壊の起点とな
り、靱性や疲労特性を低下させる原因となる。したがっ
て、V の含有は0.15% 以下まで許容する。V: 0.15% or less. V, similar to Mn, Cr, and Zr, produces dispersed particles (dispersed phase) during homogenizing heat treatment and subsequent hot forging. Since these dispersed particles have an effect of preventing grain boundary movement after recrystallization, fine crystal grains can be obtained. However, excessive content easily forms coarse Al-Fe-Si-V-based intermetallic compounds and crystal precipitates during melting and casting, becomes a starting point of fracture, and causes deterioration of toughness and fatigue properties. Therefore, V content is allowed up to 0.15%.
【0078】次に、本発明におけるAl合金鍛造材の好ま
しい製造方法について述べる。本発明におけるAl合金鍛
造材の製造自体は常法により製造が可能である。例え
ば、前記Al合金成分範囲内に溶解調整されたAl合金溶湯
を鋳造する場合には、例えば、連続鋳造圧延法、半連続
鋳造法(DC鋳造法)、ホットトップ鋳造法等の通常の
溶解鋳造法を適宜選択して鋳造する。Next, a preferred method for manufacturing the Al alloy forged material in the present invention will be described. The Al alloy forged material according to the present invention can be manufactured by an ordinary method. For example, when casting a melted Al alloy melt adjusted within the Al alloy component range, for example, ordinary melt casting such as continuous casting and rolling method, semi-continuous casting method (DC casting method), and hot top casting method. The method is appropriately selected and casting is performed.
【0079】しかし、Al合金鋳塊の結晶粒を微細化し、
かつ、粒界上に存在する晶析出物の平均粒径、晶析出物
同士の平均間隔を、本発明で規定する範囲にするために
は、Al合金溶湯を、10℃/sec以上の冷却速度で鋳造して
鋳塊とすることが好ましい。また、鋳塊の冷却速度が10
℃/sec以上とすることにより、鋳塊のデンドライト二次
アーム間隔(DAS) を30μm 以下とすることができる。一
方、これ以上冷却速度が遅いと、粒界上に存在する晶析
出物の平均粒径、晶析出物同士の平均間隔を、本発明で
規定する範囲にできず、かつ結晶粒が粗大化し、鋳塊の
デンドライト二次アーム間隔(DAS) を30μm 以下とする
ことができなくなる可能性がある。However, the crystal grains of the Al alloy ingot are refined,
And, in order to make the average particle size of the crystal precipitates existing on the grain boundaries, the average interval between the crystal precipitates within the range defined in the present invention, the Al alloy molten metal is cooled at 10 ° C / sec or more. It is preferable to cast into a ingot. In addition, the cooling rate of the ingot is 10
By setting the temperature to be at least ° C / sec, the dendrite secondary arm spacing (DAS) of the ingot can be set to 30 µm or less. On the other hand, if the cooling rate is slower than this, the average grain size of the crystal precipitates existing on the grain boundary, the average interval between the crystal precipitates, it cannot be within the range specified in the present invention, and the crystal grains become coarse, It may not be possible to reduce the dendrite secondary arm spacing (DAS) of the ingot to 30 μm or less.
【0080】次いで、このAl合金鋳塊 (鋳造材) の均質
化熱処理温度は500 〜 550℃の温度範囲とすることが好
ましい。均質化熱処理温度が550 ℃を越えて高過ぎる
と、バーニング等が生じ、鍛造割れの原因となる。ま
た、製品での靱性、疲労特性などの機械的な特性を低下
させる。また、分散粒子が粗大化し、分散粒子自体の数
も不足する。この結果、結晶粒内の分散粒子の平均サイ
ズを1100オングストローム以下に微細化できず、また、
この微細分散粒子を10個/ μm3以上の比較的多数分布さ
せることができない。このため、フラッシュ部近傍の製
品部の晶出物を固溶および微細化させられず、結晶粒を
微細化できない。Next, the homogenizing heat treatment temperature of this Al alloy ingot (cast material) is preferably in the temperature range of 500 to 550 ° C. If the homogenizing heat treatment temperature exceeds 550 ° C and is too high, burning occurs and causes forging cracks. It also reduces mechanical properties such as toughness and fatigue properties of the product. In addition, the dispersed particles become coarse and the number of dispersed particles themselves becomes insufficient. As a result, the average size of the dispersed particles within the crystal grains cannot be reduced to 1100 angstroms or less, and
A relatively large number of finely dispersed particles of 10 particles / μm 3 or more cannot be distributed. For this reason, the crystallized substances in the product portion in the vicinity of the flash portion cannot be solid-solved and refined, and the crystal grains cannot be refined.
【0081】一方、均質化熱処理温度が500 ℃未満と低
過ぎると、製品の粒界上に存在するMg2Si やAl-Fe-Si-
(Mn、Cr、Zr) 系晶析出物の平均粒径を1.2 μm 以下と
するとともに、これら晶析出物同士の平均間隔を3.0 μ
m 以上とすることが難しくなる。On the other hand, if the homogenizing heat treatment temperature is too low, less than 500 ° C., Mg 2 Si or Al-Fe-Si- existing on the grain boundaries of the product is
The average grain size of (Mn, Cr, Zr) -based crystal precipitates should be 1.2 μm or less, and the average spacing between these crystal precipitates should be 3.0 μm.
It becomes difficult to set it to m or more.
【0082】この均質化熱処理の後に、メカニカル鍛造
や油圧鍛造等により熱間鍛造して、最終製品形状( ニア
ネットシェイプ) のAl合金鍛造材に成形する。この際、
均質化熱処理後のAl合金鋳塊の熱間鍛造開始温度を350
〜 450℃とすることが好ましい。熱間鍛造開始温度が45
0 ℃を越えた場合、変形抵抗が小さくなり、鍛造終了時
や容体化処理の昇温時に、結晶粒が粗大化しやすいた
め、特にフラッシュ部近傍の製品部における結晶粒微細
化が得られない。一方、熱間鍛造開始温度が350℃未満
では、鍛造加工自体が困難となる。After this homogenizing heat treatment, hot forging is performed by mechanical forging, hydraulic forging, etc. to form an Al alloy forged material having a final product shape (near net shape). On this occasion,
The hot forging start temperature of the Al alloy ingot after the homogenizing heat treatment is set to 350
It is preferable to set the temperature to 450 ° C. Hot forging start temperature is 45
If the temperature exceeds 0 ° C., the deformation resistance becomes small, and the crystal grains are likely to become coarse at the end of forging or at the time of temperature rise in the heat treatment, so that the grain refinement cannot be obtained particularly in the product portion near the flash portion. On the other hand, if the hot forging start temperature is less than 350 ° C, the forging process itself becomes difficult.
【0083】そして、鍛造後、必要な強度および靱性、
耐食性を得るためのT6 (溶体化処理後、最大強さを得る
人工時効硬化処理) 、T7 (溶体化処理後、最大強さを得
る人工時効硬化処理条件を超えて過剰時効処理) 、T8
(溶体化処理後、冷間加工を行い、更に最大強さを得る
人工時効硬化処理) 等の調質処理を適宜行う。また、均
質化熱処理、溶体化処理には、空気炉、誘導加熱炉、硝
石炉などが適宜用いられる。更に、人工時効硬化処理に
は、空気炉、誘導加熱炉、オイルバスなどが適宜用いら
れる。溶体化処理後の冷却は水冷が好ましい。冷却速度
が低くなると、粒界上にMg2Si 、Si等が析出し、人工時
効後の製品において、粒界破壊が生じ易くなり、靱性な
らびに疲労特性を低くする。また、冷却途中に、粒内に
も、安定相Mg2Si 、Siが形成され、人工時効時に析出す
るβ' 相、β''相の析出量が減るため、強度が低下す
る。一方、冷却速度が高くなると、焼入歪み量が多くな
り、焼入後に、矯正工程が新たに必要となったり、矯正
工程の工数が増す。したがって、製品製造工程を短縮
し、低コスト化するためには、焼入歪みが緩和される50
〜85℃の温湯焼入が好ましい。ここで、温湯焼入温度が
50℃未満では焼入歪みが大きくなり、85℃を越えると冷
却速度が低くなりすぎ、靱性ならびに疲労特性、強度が
低くなる。After forging, the required strength and toughness,
T6 (artificial age hardening treatment to obtain maximum strength after solution treatment) to obtain corrosion resistance, T7 (excess aging treatment beyond artificial age hardening treatment condition to obtain maximum strength after solution treatment), T8
After the solution treatment, cold working is performed, and further, tempering treatment such as artificial age hardening treatment for obtaining maximum strength is appropriately performed. For the homogenization heat treatment and the solution heat treatment, an air furnace, an induction heating furnace, a glass stone furnace, etc. are appropriately used. Further, for the artificial age hardening treatment, an air furnace, an induction heating furnace, an oil bath or the like is appropriately used. Cooling after the solution treatment is preferably water cooling. When the cooling rate becomes low, Mg 2 Si, Si, etc. are precipitated on the grain boundaries, and the grain boundary fracture easily occurs in the product after artificial aging, and the toughness and fatigue properties are lowered. In addition, stable phases Mg 2 Si and Si are formed in the grains during cooling, and the amount of β ′ phase and β ″ phase that precipitate during artificial aging decreases, so the strength decreases. On the other hand, when the cooling rate is high, the amount of quenching strain is large, which necessitates a new straightening step after quenching or increases the number of steps in the straightening step. Therefore, in order to shorten the product manufacturing process and reduce the cost, quenching strain is reduced.
Quenching in warm water at ~ 85 ° C is preferred. Where the hot water quenching temperature is
If it is less than 50 ° C, the quenching strain becomes large, and if it exceeds 85 ° C, the cooling rate becomes too low, and the toughness, fatigue property and strength become low.
【0084】前記T7材では粒界上に析出するβ' 相の割
合が高くなる。このβ' 相は腐食環境下で溶出しにく
く、粒界腐食感受性を低くし、耐応力腐食割れ性を高め
る。一方、前記T6材で多く析出するβ''相は腐食環境下
で溶出しやすく、粒界腐食感受性を高くし、耐応力腐食
割れ性を低める。したがって、Al合金鍛造材を前記T7材
とすることで、耐力は若干低くなるものの、他の調質処
理に比して、耐食性はより高くなる。In the T7 material, the proportion of β ′ phase precipitated on the grain boundaries is high. This β ' phase is difficult to elute in a corrosive environment, reduces intergranular corrosion susceptibility, and enhances stress corrosion cracking resistance. On the other hand, the β ″ phase, which is often precipitated in the T6 material, is likely to be eluted in a corrosive environment, which increases the intergranular corrosion susceptibility and reduces the stress corrosion cracking resistance. Therefore, by using the T7 material as the Al alloy forged material, the proof stress is slightly lowered, but the corrosion resistance is higher than the other temper treatments.
【0085】なお、Al合金鍛造材に残留する鋳造組織を
無くし、強度と靱性ならびに疲労特性をより向上させる
ために、Al合金鋳塊を均質化熱処理後、押出や圧延加工
した後に、前記鍛造を行っても良い。In order to eliminate the cast structure remaining in the Al alloy forged material and further improve the strength, toughness and fatigue characteristics, the Al alloy ingot is subjected to homogenizing heat treatment, and then extruded or rolled, and then the forging is performed. You can go.
【0086】[0086]
【実施例】次に、本発明の実施例を説明する。表1 に示
す化学成分組成のAl合金鋳塊 (Al合金鋳造材、いずれも
直径φ82mmの丸棒) を、ホットトップ鋳造法により、20
℃/ sec の冷却速度により鋳造した。そして、この鋳塊
の外表面を厚さ3mm 面削して、長さ500mm に切断後、表
1 に示すように、均質化熱処理条件 (温度と時間)と鍛
造開始温度とを種々変えて、2 種類の鍛造材を作製し
た。EXAMPLES Next, examples of the present invention will be described. The Al alloy ingots with the chemical composition shown in Table 1 (Al alloy cast materials, all of which are round bars with a diameter of φ82 mm) were
It was cast at a cooling rate of ℃ / sec. Then, the outer surface of this ingot is chamfered to a thickness of 3 mm and cut to a length of 500 mm, and
As shown in Fig. 1, two types of forgings were produced by varying the homogenizing heat treatment conditions (temperature and time) and the forging start temperature.
【0087】2 種類の内、1 方の鍛造材は、機械的特性
評価用であり、自由鍛造にて、図5に平面図で示す厚さ2
5mmの円板状鍛造材1bを作製した。この円板状鍛造材1b
の鋳塊からの加工率は、加工率が低い75% 未満となるよ
う、意図的に低くした。Of the two types, one of the forged materials was for mechanical property evaluation, and was free forged to have a thickness of 2 mm as shown in the plan view in FIG.
A disc-shaped forged material 1b of 5 mm was produced. This disc-shaped forging 1b
The processing rate from the ingot was intentionally lowered so that the processing rate was less than 75%, which is low.
【0088】もう一方の鍛造材は、ミクロ組織および耐
食性評価用であり、図2 に示した上下金型を用いたメカ
ニカル鍛造により、フラッシュスタンドの隙間4mm で、
図3に示したような、製品部直径50mmでフラッシュ3 付
の丸棒状の鍛造材1aを作製した。なお、前記均質化熱処
理温度までの昇温時間は1 〜4 時間とした。The other forging material was for evaluating the microstructure and corrosion resistance, and was mechanically forged using the upper and lower molds shown in FIG.
As shown in FIG. 3, a round bar-shaped forging 1a with a flash 3 and a product diameter of 50 mm was produced. The heating time up to the homogenizing heat treatment temperature was 1 to 4 hours.
【0089】次に、これらのAl合金鍛造材を、共通し
て、空気炉を用いて、550 ℃で3 時間の溶体化処理した
後60℃の温水に焼入れを行い、その後30分以内に、180
℃×5時間の人工時効処理を行い、T6材とした。なお、
前記溶体化処理温度までの昇温時間は1 〜2 時間とし
た。Next, these Al alloy forged materials were commonly subjected to solution treatment at 550 ° C. for 3 hours using an air furnace, followed by quenching in hot water at 60 ° C., and within 30 minutes thereafter, 180
Artificial aging treatment was performed at 5 ° C for 5 hours to obtain T6 material. In addition,
The temperature rising time to the solution heat treatment temperature was 1 to 2 hours.
【0090】そして、図5 に示した円板状鍛造材1bか
ら、各々引張試験片A (L方向) とシャルピー試験片B (L
T 方向) を各5 個づつ採取し、引張強度(MPa) 、0.2%耐
力(MPa) 、伸び(%) 、シャルピー衝撃値、の平均値を各
々測定した。これらの結果を表2 に示す。From the disc-shaped forged material 1b shown in FIG. 5, tensile test pieces A (L direction) and Charpy test pieces B (L
Five samples each in the T direction) were sampled, and the average values of tensile strength (MPa), 0.2% proof stress (MPa), elongation (%), and Charpy impact value were measured. The results are shown in Table 2.
【0091】更に、図3 に示した丸棒状鍛造材1aから、
製品とフラッシュとの切断面5aの組織における型割り面
に垂直な方向の結晶粒径などの組織観察用に、切断面5a
近傍の製品部から試験片D (L方向) を、図3の拡大図で
ある図4 に示すように採取した。また、図3 に示すよう
に、応力腐食割れ試験用に、切断面5a近傍の製品部から
C リング試験片を採取した。Furthermore, from the round bar-shaped forging material 1a shown in FIG.
The cut surface 5a is used for observing the structure such as the crystal grain size in the direction perpendicular to the parting surface in the structure of the cut surface 5a between the product and the flash.
A test piece D (L direction) was taken from a nearby product section as shown in FIG. 4, which is an enlarged view of FIG. In addition, as shown in Fig. 3, for the stress corrosion cracking test, from the product part near the cut surface 5a.
C-ring test pieces were collected.
【0092】そして、切断面5aの組織における型割り面
に垂直な方向の最大結晶粒径、切断面5aの組織の結晶粒
内における50Å以上の分散粒子の平均サイズと、50Å以
上の分散粒子の密度、切断面5aの組織の粒界上に存在す
る析出物の形態 (平均粒径μm と、平均間隔μm ) 、の
測定を行った。これらの各測定条件は各々前記した通り
とした。これらの結果も表2 に示すが、表2 のAl合金番
号は表1 の番号と対応している。なお、前記機械的特性
の評価をした例のうち、機械的特性の低いものは、組織
観察や応力腐食割れ試験は行わなかった。Then, the maximum crystal grain size of the texture of the cut surface 5a in a direction perpendicular to the mold splitting surface, the average size of the dispersed particles of 50 Å or more in the crystal grains of the texture of the cut surface 5a, and the dispersed particle of 50 Å or more The density and the form of precipitates existing on the grain boundaries of the texture of the cut surface 5a (average grain size μm and average interval μm) were measured. Each of these measurement conditions was as described above. These results are also shown in Table 2, and the Al alloy numbers in Table 2 correspond to those in Table 1. Among the examples of evaluation of the mechanical properties, those having low mechanical properties were not subjected to the structure observation or the stress corrosion cracking test.
【0093】また、前記C リングの試験片を用い、応力
腐食割れ試験を行った。応力腐食割れ試験条件は、前記
Cリング試験片をASTM G47の交互浸漬法の規定に準じて
行った。但し、試験条件は、更に、鍛造材が切断面5a部
分に対しST方向に引張応力が付加されて使用されること
を模擬して、C リング試験片のST方向に、前記機械的特
性の試験片のL 方向の耐力の75% の応力を負荷した状態
とした。この状態で、C リング試験片の塩水への浸漬と
引き上げを繰り返して90日間行い、試験片の応力腐食割
れ発生の有無を確認した。これらの結果を、応力腐食割
れが発生している場合を×、応力腐食割れではないが、
応力腐食割れに至る可能性の高い粒界腐食が発生してい
る場合を△、応力腐食割れや粒界腐食が発生していない
場合 (表面的な全面腐食が発生している場合を含む) を
○として、表2 に示す。A stress corrosion cracking test was conducted using the C ring test piece. The stress corrosion cracking test conditions are as described above.
C-ring specimens were tested according to the ASTM G47 Alternate Dipping Method. However, the test conditions further simulate that the forged material is used with tensile stress applied to the cut surface 5a in the ST direction, and the mechanical properties are tested in the ST direction of the C ring test piece. A stress of 75% of the yield strength of the piece in the L direction was applied. In this state, the C-ring test piece was repeatedly immersed in salt water and pulled up for 90 days to confirm whether or not stress corrosion cracking occurred in the test piece. These results are × when stress corrosion cracking occurs, but not stress corrosion cracking,
△ indicates that intergranular corrosion that is likely to lead to stress corrosion cracking has occurred, and that no stress corrosion cracking or intergranular corrosion has occurred (including cases where surface general corrosion has occurred). Table 2 shows as ○.
【0094】表2 から明らかな通り、表1 のNo.1〜7 ま
での本発明範囲内の化学成分組成とし、T6材での切断面
5aの組織における型割り面に垂直な方向の最大の結晶粒
径を400 μm 以下とした発明例No.1〜7 は、いずれも応
力腐食割れ性に優れている。As is clear from Table 2, the chemical composition of No. 1 to No. 7 in Table 1 is within the scope of the present invention, and the cut surface of the T6 material is
Inventive Examples Nos. 1 to 7 in which the maximum crystal grain size in the direction perpendicular to the parting plane in the structure of 5a is 400 μm or less are all excellent in stress corrosion cracking resistance.
【0095】また、発明例No.1〜7 は、鋳塊のデンドラ
イト二次アーム間隔(DAS) が30μm以下と小さく、切断
面5aの組織における結晶粒内における分散粒子の平均サ
イズと密度、切断面5aの組織の粒界上に存在する析出物
の平均粒径と平均間隔の好ましい条件を満足し、鋳塊か
らの加工率が低くても、耐力 (σ0.2)の平均値が300MPa
以上およびシャルピー衝撃値の平均値が10J/cm2 以上
と、高強度と高靱性を確保している。Inventive Examples Nos. 1 to 7 have small dendrite secondary arm intervals (DAS) of the ingot of 30 μm or less, the average size and density of the dispersed particles in the crystal grains of the cut surface 5a, and the cutting Satisfying the preferred conditions of the average grain size and average spacing of the precipitates present on the grain boundaries of the structure of the surface 5a, even if the processing rate from the ingot is low, the average value of the proof stress (σ 0.2 ) is 300 MPa.
Above, and the average value of Charpy impact value is 10 J / cm 2 or more, high strength and high toughness are secured.
【0096】これに対し、表1 、2 から明らかな通り、
表1 、2 から明らかな通り、本発明範囲内の化学成分組
成としても、T6材での切断面5aの組織における型割り面
に垂直な方向の最大の結晶粒径が400 μm を越える比較
例No.9、10、11は、いずれも応力腐食割れ性に劣ってい
る。On the other hand, as is clear from Tables 1 and 2,
As is clear from Tables 1 and 2, even in the chemical composition within the scope of the present invention, a comparative example in which the maximum crystal grain size in the direction perpendicular to the parting plane in the structure of the cut surface 5a in the T6 material exceeds 400 μm Nos. 9, 10, and 11 are all inferior in stress corrosion cracking resistance.
【0097】また、均質化熱処理温度や熱間鍛造開始温
度が各々好ましい範囲を外れるか上下限である比較例N
o.8、9 、10、11、14と、Mg量が下限に外れる比較例No.
13、Mn量が上限に外れる比較例No. 15、更に、鋳塊の
デンドライト二次アーム間隔(DAS) が30μm を越える比
較例No.12 は、耐力 (σ0.2)あるいはシャルピー衝撃
値、伸びなどの機械的な特性が発明例に比して著しく劣
っている。In addition, Comparative Example N in which the homogenizing heat treatment temperature and the hot forging start temperature are out of the preferred ranges or have the upper and lower limits, respectively.
o.8, 9, 10, 11, 14 and Comparative Example No. in which the amount of Mg is out of the lower limit.
13, Comparative Example No. 15 in which the amount of Mn deviates from the upper limit, and Comparative Example No. 12 in which the secondary dendrite arm interval (DAS) of the ingot exceeds 30 μm, the proof stress (σ 0.2 ) or Charpy impact value, elongation, etc. The mechanical properties of are significantly inferior to the invention examples.
【0098】したがって、これらの結果から、本発明Al
合金鍛造材組織の要件や好ましい製造条件の臨界的な意
義が分かる。Therefore, from these results, the present invention Al
The critical significance of requirements for alloy forging structure and preferable manufacturing conditions can be understood.
【0099】[0099]
【表1】 [Table 1]
【0100】[0100]
【表2】 [Table 2]
【0101】[0101]
【発明の効果】本発明によれば、前記厳しい使用環境下
にあっても、Al合金鍛造材の製品とフラッシュとの切断
面の組織の部分に応力腐食割れが生じず、かつ高強度、
高靱性であるAl合金鍛造材および鍛造材用素材を提供す
ることができる。したがって、Al-Mg-Si系Al合金鍛造材
の輸送機用への用途の拡大を図ることができる点で、多
大な工業的な価値を有するものである。EFFECTS OF THE INVENTION According to the present invention, stress corrosion cracking does not occur in the portion of the structure of the cut surface between the product of the Al alloy forged material and the flash even under the severe use environment, and high strength,
It is possible to provide an Al alloy forged material having high toughness and a material for forged material. Therefore, the use of the Al-Mg-Si based Al alloy forged material for transport aircraft can be expanded, which is of great industrial value.
【図1】本発明Al合金鍛造材で規定する組織部分のST方
向断面のマクロ組織を示す断面図である。FIG. 1 is a cross-sectional view showing a macrostructure of a ST-direction cross section of a structure portion defined by an Al alloy forged material of the present invention.
【図2】本発明Al合金鍛造用金型を示す断面図である。FIG. 2 is a cross-sectional view showing an Al alloy forging die of the present invention.
【図3】本発明実施例における試験片採取部位を示すAl
合金鍛造材の斜視図である。FIG. 3 is an Al showing a test piece collection site in an example of the present invention.
It is a perspective view of an alloy forging material.
【図4】図3の部分拡大図である。FIG. 4 is a partially enlarged view of FIG.
【図5】本発明実施例における試験片採取部位を示すAl
合金鍛造材の平面図である。FIG. 5 is an Al showing a test piece sampling site in the example of the present invention.
It is a top view of an alloy forged material.
【図6】本発明Al合金鍛造材における分散粒子の分布状
況を示す組織図である。FIG. 6 is a structural diagram showing a distribution state of dispersed particles in the Al alloy forged material of the present invention.
1: Al合金鍛造材、2:製品部、3:フラッシュ、4:型割り
面、5: フラッシュ切断線、6:メタルフロー、7:上型、
8:下型、9: ガッタ、10: フラッシュスタンド、1: Al alloy forged material, 2: Product part, 3: Flash, 4: Molding surface, 5: Flash cutting line, 6: Metal flow, 7: Upper mold,
8: Lower mold, 9: Gutta, 10: Flash stand,
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 FI テーマコート゛(参考) C22F 1/00 624 C22F 1/00 624 630 630A 630Z 631 631Z 682 682 691 691B (72)発明者 澤田 洋樹 三重県員弁郡大安町大字梅戸1100番地 株 式会社神戸製鋼所大安工場内─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 7 Identification code FI theme code (reference) C22F 1/00 624 C22F 1/00 624 630 630A 630Z 631 631Z 682 682 691 691B (72) Inventor Hiroki Sawada Mie 1100 Umeto, Daian-cho, Oita-cho, Kenben-gun Inside the Daian Plant of Kobe Steel Co., Ltd.
Claims (12)
に、Mn:0.01 〜0.6%、Cr:0.1〜0.2%およびZr:0.1〜0.2%
の一種または二種以上を含み、残部Alおよび不可避的不
純物からなるアルミニウム合金鍛造材であって、人工時
効処理後のアルミニウム合金鍛造材の、0.2%耐力が300M
Pa以上およびシャルピー衝撃値が10J/cm2 以上であり、
更に、製品とフラッシュとの切断面の組織における、型
割り面に垂直な方向の結晶粒径であって、この結晶粒径
の内の最大のものが400 μm 以下であることを特徴とす
る耐応力腐食割れ性に優れたアルミニウム合金鍛造材。Claims: 1. Contains Mg: 0.6-1.8%, Si: 0.4-1.8%, Mn: 0.01-0.6%, Cr: 0.1-0.2% and Zr: 0.1-0.2%.
The aluminum alloy forged material containing one or two or more of the above, and the balance Al and unavoidable impurities, and the 0.2% proof stress of the aluminum alloy forged material after artificial aging treatment is 300M.
Pa or more and Charpy impact value is 10 J / cm 2 or more,
Further, in the structure of the cut surface between the product and the flash, the crystal grain size in the direction perpendicular to the mold splitting surface, and the maximum grain size is 400 μm or less. Aluminum alloy forged material with excellent stress corrosion cracking.
500 〜 550℃の温度で均質化熱処理した後に熱間鍛造し
て得られる請求項1に記載の耐応力腐食割れ性に優れた
アルミニウム合金鍛造材。2. The forged material is an aluminum alloy ingot
The aluminum alloy forging material excellent in stress corrosion cracking resistance according to claim 1, which is obtained by hot forging after homogenizing heat treatment at a temperature of 500 to 550 ° C.
ニウム合金鋳塊を開始温度が350 〜 450℃で熱間鍛造し
て得られる請求項1または2に記載の耐応力腐食割れ性
に優れたアルミニウム合金鍛造材。3. The stress corrosion cracking resistance according to claim 1 or 2, wherein the forged material is obtained by hot forging an aluminum alloy ingot after homogenizing heat treatment at a starting temperature of 350 to 450 ° C. Aluminum alloy forgings.
る晶析出物の平均粒径を1.2 μm 以下とするとともに、
これら晶析出物同士の平均間隔を3.0 μm 以上とし、更
に、結晶粒内の分散粒子の平均サイズが1100オングスト
ローム以下であるとともに、50オングストローム以上の
サイズの分散粒子が10個/ μm3以上存在する請求項1乃
至3の何れか1項に記載の耐応力腐食割れ性に優れたア
ルミニウム合金鍛造材。4. The average grain size of crystal precipitates existing on the crystal grain boundaries of the forged material structure is 1.2 μm or less, and
The average interval between these crystal precipitates is 3.0 μm or more, and further, the average size of dispersed particles in the crystal grains is 1100 Å or less, and there are 10 or μm 3 or more dispersed particles having a size of 50 Å or more. An aluminum alloy forged material excellent in stress corrosion cracking resistance according to any one of claims 1 to 3.
間隔(DAS) が30μm以下となるように鋳造した鋳塊を用
いた請求項1乃至4の何れか1項に記載の耐応力腐食割
れ性に優れたアルミニウム合金鍛造材。5. The stress corrosion cracking resistance according to any one of claims 1 to 4, wherein the forged material is an ingot cast such that a secondary dendrite arm interval (DAS) is 30 μm or less. Excellent aluminum alloy forging material.
に鍛造する請求項5に記載の耐応力腐食割れ性に優れた
アルミニウム合金鍛造材。6. The forged aluminum alloy material having excellent resistance to stress corrosion cracking according to claim 5, wherein the ingot is extruded or rolled and then forged.
とフラッシュとの切断面の組織に対しST方向に引張応力
が付加されて使用される請求項1乃至6の何れか1項に
記載の耐応力腐食割れ性に優れたアルミニウム合金鍛造
材。7. The stress resistance according to claim 1, wherein the forged aluminum alloy material is used by applying tensile stress in the ST direction to the structure of the cut surface between the product and the flash. Aluminum alloy forged material with excellent corrosion cracking resistance.
満の部位を有する請求項1乃至7の何れか1項に記載の
耐応力腐食割れ性に優れたアルミニウム合金鍛造材。8. The aluminum alloy forging material excellent in stress corrosion cracking resistance according to any one of claims 1 to 7, wherein the forging material has a portion having a hot forging rate of less than 75%.
ラッシュとの切断面の厚みが30mm以上である請求項1乃
至8の何れか1項に記載の耐応力腐食割れ性に優れたア
ルミニウム合金鍛造材。9. The aluminum alloy forging material excellent in stress corrosion cracking resistance according to claim 1, wherein a thickness of a cut surface between the product of the aluminum alloy forging material and the flash is 30 mm or more. .
の構造材用である請求項1乃至9の何れか1項に記載の
耐応力腐食割れ性に優れたアルミニウム合金鍛造材。10. The aluminum alloy forged material excellent in stress corrosion cracking resistance according to claim 1, wherein the aluminum alloy forged material is used for a structural material of a transportation machine.
記載の鍛造材用素材であって、アルミニウム合金鋳塊か
らなるとともに、Mg:0.6〜1.8%、Si:0.4〜1.8%を含み、
更に、Mn:0.1〜0.6%、Cr:0.1〜0.2%およびZr:0.1〜0.2%
の一種または二種以上を含み、残部Alおよび不可避的不
純物からなり、鋳塊組織におけるデンドライト二次アー
ム間隔が30μm 以下であることを特徴とする耐応力腐食
割れ性に優れたアルミニウム合金鍛造材用素材。11. The forging material according to any one of claims 1 to 10, which is made of an aluminum alloy ingot and contains Mg: 0.6 to 1.8%, Si: 0.4 to 1.8%. ,
Furthermore, Mn: 0.1-0.6%, Cr: 0.1-0.2% and Zr: 0.1-0.2%
For aluminum alloy forgings excellent in stress corrosion cracking resistance, characterized in that the dendrite secondary arm spacing in the ingot structure is 30 μm or less, including the balance Al and unavoidable impurities. Material.
押出或いは熱間圧延により加工した請求項11に記載の
耐応力腐食割れ性に優れたアルミニウム合金鍛造材用素
材。12. The material for an aluminum alloy forging material excellent in stress corrosion cracking resistance according to claim 11, wherein the aluminum alloy ingot is further processed by hot extrusion or hot rolling.
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