JPH06145920A - Production of al-li alloy forged material excellent in toughness - Google Patents

Abstract

PURPOSE:To clarify the producing conditions for improving the toughness of an Al-Li alloy forged material. CONSTITUTION:An Al-Li alloy ingot contg., by weight, 1.0 to 3.0% Li, 1.0 to 3.0% Cu and 0.04 to 0.20% Zr or furthermore contg. 0.5 to 2.O% Mg, and the balance Al with inevitable impurities is subjected to soaking treatment and is thereafter subjected to hot forging at 340 to 420 deg.C for >= two times to regulate its cumulative forging ratio into 8 to 16. In this way, its structure is formed into an unrecrystallized one in which the grain size of subcrystals is regulated to <=10mum, by which the Al-Li alloy forged material excellent in toughness can be produced.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明はＡｌ−Ｌｉ系合金鍛造材
の製造方法に関し、特に靭性を向上させたものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an Al-Li alloy forged material, and more particularly, to a material having improved toughness.

【０００２】[0002]

【従来の技術及び発明が解決しようとする課題】現在Ａ
ｌ−Ｌｉ系合金としては2090（Ａｌ− 1.9〜2.6 wt％Ｌ
ｉ− 2.4〜3.0wt％Ｃｕ−0.08〜0.16wt％Ｚｒ）、2091
（Ａｌ− 1.7〜2.3 wt％Ｌｉ− 1.8〜2.5 wt％Ｃｕ−
1.1〜1.9 wt％Ｍｇ−0.04〜0.16wt％Ｚｒ）、8090（Ａ
ｌ− 2.2〜2.7 wt％Ｌｉ− 1.0〜1.6 wt％Ｃｕ− 0.6〜
1.3 wt％Ｍｇ−0.04〜0.16wt％Ｚｒ）等の規格合金があ
り、これら材料は高比強度、高比剛性という特性を備え
ているため、航空宇宙、車両、自動車等各種の構造用材
料としての実用化が期待されているものである。2. Prior Art and Problems to be Solved by the Invention
As an l-Li alloy, 2090 (Al-1.9 to 2.6 wt% L
i-2.4 to 3.0 wt% Cu-0.08 to 0.16 wt% Zr), 2091
(Al-1.7 to 2.3 wt% Li- 1.8 to 2.5 wt% Cu-
1.1-1.9 wt% Mg-0.04-0.16 wt% Zr), 8090 (A
l-2.2-2.7 wt% Li-1.0-1.6 wt% Cu-0.6-
There are standard alloys such as 1.3 wt% Mg-0.04 to 0.16 wt% Zr). Since these materials have the characteristics of high specific strength and high specific rigidity, they are used as various structural materials for aerospace, vehicles, automobiles, etc. Is expected to be put to practical use.

【０００３】しかし、これらの材料の実用化の最大の問
題点は低靭性であることであり、これを解決することが
これらの合金研究の最大の問題点となっている。低靭性
の原因は転位の局部粗大すべりによる粒界への応力集中
であるとされており、これを解決するためには、サブ組
織を微細化することにより、局部粗大滑りによる応力集
中を緩和する必要がある。しかしこれまでＡｌ−Ｌｉ系
合金鍛造材に関しサブ組織を微細化し靭性を向上させる
ための材料の製造方法及び条件が明確でなかった。However, the biggest problem in putting these materials to practical use is their low toughness, and solving these problems is the biggest problem in research on these alloys. It is said that the cause of low toughness is stress concentration at grain boundaries due to local coarse slip of dislocations.To solve this, the stress concentration due to local coarse slip is relaxed by making the substructure finer. There is a need. However, until now, the manufacturing method and conditions of the material for refining the substructure and improving the toughness of the Al-Li alloy forged material have not been clarified.

【０００４】[0004]

【課題を解決するための手段】本発明はこれに鑑み、こ
れらＡｌ−Ｌｉ系合金鍛造材のサブ組織微細化による靭
性向上について検討した結果、靭性を向上させる製造法
を開発したものである。In view of this, the present invention has developed a manufacturing method for improving the toughness as a result of studying the improvement of the toughness by refining the substructure of these Al-Li alloy forged materials.

【０００５】即ち本発明は、Ｌｉ： 1.0〜3.0 wt％、Ｃ
ｕ： 1.0〜3.0 wt％、Ｚｒ：0.04〜0.20wt％を含み、又
はこれらにさらにＭｇ： 0.5〜2.0 wt％を含み、残部Ａ
ｌと不可避的不純物からなるＡｌ−Ｌｉ系合金鋳塊を均
熱処理後、 340〜420 ℃の温度で２回以上熱間鍛造を行
って累積鍛造比を８〜16とすることにより、サブ結晶粒
径を10μｍ以下の未再結晶組織とすることを特徴とする
ものである。That is, according to the present invention, Li: 1.0 to 3.0 wt%, C
u: 1.0 to 3.0 wt%, Zr: 0.04 to 0.20 wt%, or these further containing Mg: 0.5 to 2.0 wt%, the balance A
After soaking the Al-Li alloy ingot consisting of 1 and unavoidable impurities, hot forging is performed twice or more at a temperature of 340 to 420 ° C. to obtain a cumulative forging ratio of 8 to 16 to obtain sub crystal grains. It is characterized by having a non-recrystallized structure with a diameter of 10 μm or less.

【０００６】[0006]

【作用】まず本発明においてＡｌ−Ｌｉ系合金の組成を
上記のように限定した理由を説明する。First, the reason why the composition of the Al--Li alloy is limited as described above in the present invention will be explained.

【０００７】Ｌｉは軽量化及び高強度化のために含有さ
せるものであり、その含有量を 1.0〜3.0 wt％と限定し
たのは、 1.0wt％未満では軽量化の効果及び高強度・高
剛性化の効果が少なく、 3.0wt％を越えると鋳造割れ感
受性を増加させると同時に粗大なδ′を生成するなどし
て合金の延性及び靭性を低下させるからである。Li is contained in order to reduce the weight and increase the strength. The content of Li is limited to 1.0 to 3.0 wt% because when it is less than 1.0 wt%, the effect of weight reduction and the high strength and high rigidity are achieved. This is because the alloying effect is small, and if it exceeds 3.0% by weight, the susceptibility to casting cracking is increased, and at the same time, coarse δ'is produced and the ductility and toughness of the alloy are reduced.

【０００８】ＣｕはＡｌ−Ｃｕ系の板状析出物θ′（Ａ
ｌ₂ Ｃｕ）やＡｌ−Ｃｕ−Ｌｉ系の板状の析出相Ｔ₁ 相
（Ａｌ₂ ＣｕＬｉ）を生成し、強度及び靭性の向上に寄
与する。しかしてその含有量が 1.0wt％未満では強度及
び靭性向上の効果が不足し、3.0 wt％を越えると上記効
果が飽和すると同時に軽量化が損なわれる。なお本合金
にＭｇを含まない場合のＣｕの含有量は 1.5〜3.0 wt％
が望ましく、またＭｇを含む合金の場合はＭｇによる強
度向上効果も期待できるのでＣｕの含有量は1.0 〜2.5
wt％程度でも良い。Cu is an Al--Cu based plate-like precipitate θ '(A
L ₂ Cu) or an Al—Cu—Li-based plate-like precipitation phase T ₁ phase (Al ₂ CuLi) is generated, which contributes to improvement in strength and toughness. If the content is less than 1.0 wt%, the effect of improving strength and toughness is insufficient, and if it exceeds 3.0 wt%, the above effect is saturated and the weight reduction is impaired. If the alloy does not contain Mg, the Cu content is 1.5 to 3.0 wt%
Is desirable, and in the case of an alloy containing Mg, the effect of improving strength by Mg can be expected, so the Cu content is 1.0 to 2.5.
It may be about wt%.

【０００９】Ｚｒは鋳造組織を微細化すると共に再結晶
の抑止効果があるので合金組織を微細な未再結晶組織に
するために含有させるものであるが、その含有量が0.04
wt％未満では上記効果が不足し、0.20wt％を越えるとそ
の効果が飽和すると同時にＡｌ−Ｚｒの粗大金属間化合
物を生成して強度、靭性及び延性等が低下する。Zr has the effect of refining the cast structure and suppressing recrystallization, so it is contained in order to make the alloy structure a fine unrecrystallized structure, but its content is 0.04.
If it is less than wt%, the above effect is insufficient, and if it exceeds 0.20 wt%, the effect is saturated, and at the same time, a coarse intermetallic compound of Al-Zr is formed to lower strength, toughness, ductility and the like.

【００１０】またＭｇは固溶効果により材料の延性及び
靭性を低下させることなく合金を強化すると同時に、Ａ
ｌ−Ｃｕ−Ｍｇ系の準安定相の板状析出物Ｓ′（Ａｌ₂
ＣｕＭｇ）を生成し、これによりさらに強度向上に寄与
する。しかしてＭｇ含有量が 0.5wt％未満では強度向上
の効果が少く、 2.0wt％を越えると強度は向上するもの
の靭性及び延性が低下してしまう。Further, Mg strengthens the alloy by the solid solution effect without lowering the ductility and toughness of the material, and at the same time, A
1-Cu-Mg system metastable phase plate-like precipitate S '(Al ₂
CuMg) is produced, which further contributes to the strength improvement. However, if the Mg content is less than 0.5 wt%, the effect of improving the strength is small, and if it exceeds 2.0 wt%, the strength is improved but the toughness and ductility are deteriorated.

【００１１】また上記Ａｌ合金に対してＦｅ≦0.30wt
％、Ｓｉ≦0.20wt％、Ｚｎ≦0.25wt％、Ｔｉ≦0.15wt
％、Ｃｒ≦0.10wt％、Ｍｎ≦0.10wt％等は通常の不純物
であって、これらが含有されても本発明の効果を損うこ
とはないが、これらの不純物は化合物を作るか、又は亜
粒界に偏析する等して、靭性を低下させるため、可能な
らばＦｅ≦0.10wt％、Ｓｉ≦0.10wt％、Ｚｎ≦0.10wt
％、Ｔｉ≦0.05wt％、Ｃｒ≦0.05wt％、Ｍｎ≦0.05wt％
程度に少ない方が望ましい。特にＴｉは0.02〜0.05wt％
程度は鋳塊結晶粒の微細化のため積極的に添加される。Further, with respect to the above Al alloy, Fe ≦ 0.30 wt
%, Si ≦ 0.20 wt%, Zn ≦ 0.25 wt%, Ti ≦ 0.15 wt
%, Cr ≦ 0.10 wt%, Mn ≦ 0.10 wt% and the like are ordinary impurities, and the inclusion of these does not impair the effects of the present invention, but these impurities form a compound, or If possible, Fe ≦ 0.10 wt%, Si ≦ 0.10 wt%, Zn ≦ 0.10 wt in order to reduce toughness by segregating to sub-grain boundaries.
%, Ti ≦ 0.05 wt%, Cr ≦ 0.05 wt%, Mn ≦ 0.05 wt%
It is desirable that the number is small. Especially Ti is 0.02-0.05wt%
The degree is positively added for refining ingot crystal grains.

【００１２】本発明では上記のＡｌ−Ｌｉ系合金溶湯を
鋳造した後、Ｚｒ系化合物を微細分散させることにより
サブ組織を未再結晶組織とするため、面削後Ａｌ−Ｚｒ
の析出Ｃ曲線ノーズ近傍の 500℃以下と、さらに添加元
素や不純物元素をできるだけ固溶させるため、それより
高温の 520℃近傍での２段熱処理を行う。その後、これ
を熱間押出、鍛造予備加熱、熱間鍛造（荒鍛造→仕上げ
鍛造）を行った後、さらに溶体化、コイニング型による
冷間圧縮、時効のＴ８処理を行うか、又は鍛造予備加熱
・熱間鍛造、溶体化、時効のＴ６処理を行う工程が多く
とられているが、本合金は高強度高靭性が目的であるた
め通常はＴ８処理が選択される。なおＴ８処理時におけ
る溶体化処理後のストレッチは強化相の均一な析出サイ
トを与えるためのもので、これにより強度と靭性がさら
に改善される。In the present invention, after casting the above Al-Li alloy melt, the Zr compound is finely dispersed to make the substructure an unrecrystallized structure.
In order to make the additive element and the impurity element as a solid solution as much as possible at 500 ° C or less near the nose of the precipitation C curve, a two-step heat treatment is performed at a temperature higher than 520 ° C. After that, this is subjected to hot extrusion, forging preheating, hot forging (rough forging → finish forging), and then solution treatment, cold compression by coining die, aging T8 treatment, or forging preheating. -Many steps are performed for hot forging, solution treatment, and aging T6 treatment, but since this alloy aims at high strength and high toughness, T8 treatment is usually selected. The stretch after the solution treatment at the time of T8 treatment is to provide uniform precipitation sites of the strengthening phase, and thereby the strength and toughness are further improved.

【００１３】そして本発明の製造法において上記熱間鍛
造温度を 340〜420 ℃としたのは、鍛造性が良好で、か
つ組織的にもサブ結晶粒径が10μｍ以下の微細なものが
得られるからである。しかして鍛造温度が 340℃未満で
は、変形能が低くて鍛造割れが生じると同時にプレスの
所要圧力も高くなる等鍛造性に問題があり、一方 420℃
を越えるとサブ結晶粒が粗大化して粒径が10μｍを越え
てしまう。さらに鍛造温度が 450℃を越えると加工発熱
により材料温度が上昇して熱間割れを引き起してしま
う。In the manufacturing method of the present invention, the hot forging temperature is set to 340 to 420 ° C., because the forgeability is good, and the subcrystal grain size is 10 μm or less. Because. However, if the forging temperature is less than 340 ° C, there is a problem in forgeability such that the deformability is low and forging cracks occur, and at the same time the required pressure of the press becomes high.
If it exceeds, the sub-crystal grains become coarse and the grain size exceeds 10 μm. Further, if the forging temperature exceeds 450 ° C, the material temperature rises due to heat generation during processing, causing hot cracking.

【００１４】また上記温度で行う鍛造を２回以上と限定
したのは、１回の鍛造で鍛造比を８以上とすると変形能
が小さいので割れを生じると同時にプレス圧力が増大し
てしまう問題があるため、２回以上の鍛造で鍛造比８以
上を得るものである。Further, the reason that the forging carried out at the above temperature is limited to two times or more is that when the forging ratio is 8 or more in one forging, the deformability is small, so that cracking occurs and at the same time the pressing pressure increases. Therefore, a forging ratio of 8 or more is obtained by forging twice or more.

【００１５】なお１回目の鍛造で鍛造比を４以下とする
と安定した鍛造組織を得ることができないため、１回目
の鍛造での鍛造比は４〜８とするのが望ましく、２回目
以降の鍛造において累積の鍛造比を８〜16とするもので
ある。そして累積鍛造比が16を越えると材料の変形能が
不足して割れや座屈と寸法不良が発生し、８未満ではサ
ブ組織の微細化効果が不足してサブ結晶粒径が10μｍを
越えるため靭性の改善効果が少ない。Since a stable forging structure cannot be obtained when the forging ratio is 4 or less in the first forging, the forging ratio in the first forging is preferably set to 4 to 8 and the forging in the second and subsequent forgings is preferable. In the above, the cumulative forging ratio is 8-16. If the cumulative forging ratio exceeds 16, the deformability of the material is insufficient and cracks, buckling and dimensional defects occur. If it is less than 8, the sub-structure refinement effect is insufficient and the sub-crystal grain size exceeds 10 μm. Little improvement effect on toughness.

【００１６】また本発明において得られる鍛造材の微細
組織を未再結晶組織とし、そのサブ結晶粒径を10μｍ以
下と規定したのは、このように微細化することにより局
部粗大滑りによる転位の集積によって起こる結晶粒界へ
の応力集中を緩和し、粒界破壊傾向を減少させて粒内滑
りを増加させることにより靭性を向上させるためであ
る。Further, the fine structure of the forged material obtained in the present invention is defined as a non-recrystallized structure and the sub-crystal grain size is defined as 10 μm or less. This is to alleviate the stress concentration on the crystal grain boundaries caused by the above, reduce the tendency to break at the grain boundaries, and increase the intragranular slip, thereby improving the toughness.

【００１７】[0017]

【実施例】次に本発明を実施例によりさらに説明する。EXAMPLES The present invention will be further described with reference to examples.

【００１８】表１に示す組成のＡｌ−Ｌｉ系規格合金
Ａ，Ｂ及びＣをそれぞれＡｒガス雰囲気中で溶解後、 2
30mmφ×500mm Ｌの半連続水冷鋳塊ビレットを得た。こ
れらビレットを 450±20℃×24時間及び 520±20℃×４
時間の２段均熱処理後、押出温度 400℃で60mmφの丸棒
に熱間押出した。Al-Li standard alloys A, B and C having the compositions shown in Table 1 were melted in an Ar gas atmosphere, respectively, and then 2
A 30 mmφ × 500 mm L semi-continuous water-cooled ingot billet was obtained. These billets are 450 ± 20 ℃ × 24 hours and 520 ± 20 ℃ × 4
After the two-stage soaking for an hour, hot extrusion was performed at a extrusion temperature of 400 ° C. into a round bar of 60 mmφ.

【００１９】その後以下に示す工程に従ってこれら合金
Ａ，Ｂ，Ｃについて表２に示すように 320〜470 ℃の各
鍛造温度に加熱保持してそれぞれ同表に示すような累積
鍛造比となるように１次及び２次の熱間鍛造を施した
（このとき鍛造の型温度は 380〜400 ℃とした）。次に
鍛造後の各合金について 520±20℃×60分の溶体化処理
後、コイニング型により合金Ａについては６％及び合金
Ｂと合金Ｃについては３％の冷間圧縮を行い、その後時
効温度 160℃の時効曲線のピーク近傍に強度調整してＴ
８材の試験材料とした。Thereafter, the alloys A, B and C were heated and maintained at the respective forging temperatures of 320 to 470 ° C. as shown in Table 2 according to the following steps so that the cumulative forging ratios shown in the same table were obtained. Primary and secondary hot forging were performed (at this time, the die temperature for forging was 380 to 400 ° C). Next, each alloy after forging is subjected to solution treatment at 520 ± 20 ° C for 60 minutes, then cold-pressed to 6% for alloy A and 3% for alloys B and C by the coining type, and then the aging temperature. Adjust the strength near the peak of the aging curve at 160 ° C
Eight test materials were used.

【００２０】 [0020]

【００２１】このように調整して得られた試験材料につ
いて、引張試験により機械的性質を調べ、2000倍で撮影
した透過電子顕微鏡写真５枚の平均粒径よりサブ結晶粒
径を求め、また計装化シャルピー試験におけるＬ−Ｔ方
向の全吸収エネルギーにより靭性を評価し、さらに鍛造
性については鍛造後材料に割れが発生したり寸法精度が
悪化しているものについて鍛造性を×とし、そのような
欠陥の発生しなかったものについては鍛造性を○として
評価し、これらの結果を表２に併記した。なお靭性は計
装化シャルピー試験における全吸収エネルギーが高い程
優れるものである。The mechanical properties of the test material thus prepared were examined by a tensile test, and the sub-crystal grain size was determined from the average grain size of five transmission electron microscope photographs taken at 2000 times. The toughness is evaluated by the total absorbed energy in the L-T direction in the mounting Charpy test. Further, for the forgeability, the forgeability is set to x for those in which cracks have occurred in the material after forging or the dimensional accuracy has deteriorated. For those with no significant defects, the forgeability was evaluated as ◯, and these results are also shown in Table 2. The higher the total absorbed energy in the instrumented Charpy test, the better the toughness.

【００２２】[0022]

【表１】 [Table 1]

【００２３】[0023]

【表２】 [Table 2]

【００２４】表２から、同じ合金から製造した試験材料
であっても、本発明製造法によるものは比較製造法によ
るものに比べて靭性及び鍛造性の両者に優れていること
が判る。これに対して累積鍛造比の大き過ぎる比較例Ｎ
o.16, 20, 24や鍛造温度の低過ぎる比較例Ｎo.17, 21,
25は靭性は良好なるも鍛造性に劣り、鍛造温度の高過ぎ
る比較例Ｎo.18, 19, 22, 23, 26, 27はいずれも靭性が
劣ることが明らかである。It can be seen from Table 2 that even the test materials manufactured from the same alloy are superior in both toughness and forgeability to those manufactured by the manufacturing method of the present invention as compared with those manufactured by the comparative manufacturing method. On the other hand, Comparative Example N in which the cumulative forging ratio is too large
o.16, 20, 24 and Comparative Example with too low forging temperature No. 17, 21, 21
It is clear that No. 25 has good toughness but poor forgeability, and Comparative Examples Nos. 18, 19, 22, 23, 26 and 27 having too high a forging temperature all have poor toughness.

【００２５】[0025]

【発明の効果】このように本発明によれば、高比強度と
高比剛性を有するＡｌ−Ｌｉ系合金鍛造材の靭性を向上
させる条件が明確となり、実用材料として十分に使用で
きる材料が提供できるようになった等の顕著な効果を有
する。As described above, according to the present invention, the conditions for improving the toughness of an Al-Li alloy forged material having high specific strength and high specific rigidity are clarified, and a material that can be sufficiently used as a practical material is provided. It has a remarkable effect such as being able to.

Claims (2)

【特許請求の範囲】[Claims] 【請求項１】 Ｌｉ： 1.0〜3.0 wt％、Ｃｕ： 1.0〜3.
0 wt％、Ｚｒ：0.04〜0.20wt％を含み、残部Ａｌと不可
避的不純物からなるＡｌ−Ｌｉ系合金鋳塊を均熱処理
後、 340〜420 ℃の温度で２回以上熱間鍛造を行って累
積鍛造比を８〜16とすることにより、サブ結晶粒径を10
μｍ以下の未再結晶組織とすることを特徴とする靭性の
優れたＡｌ−Ｌｉ系合金鍛造材の製造方法。1. Li: 1.0 to 3.0 wt%, Cu: 1.0 to 3.
After soaking the Al-Li alloy ingot containing 0 wt% and Zr: 0.04 to 0.20 wt% and the balance Al and unavoidable impurities, hot forging is performed twice or more at a temperature of 340 to 420 ° C. By setting the cumulative forging ratio to 8 to 16, the sub crystal grain size is 10
A method for producing an Al-Li-based alloy forged material having excellent toughness, which has a non-recrystallized structure of μm or less. 【請求項２】 Ｌｉ： 1.0〜3.0 wt％、Ｃｕ： 1.0〜3.
0 wt％、Ｍｇ： 0.5〜2.0 wt％、Ｚｒ：0.04〜0.20wt％
を含み、残部Ａｌと不可避的不純物からなるＡｌ−Ｌｉ
系合金鋳塊を均熱処理後、 340〜420 ℃の温度で２回以
上熱間鍛造を行って累積鍛造比を８〜16とすることによ
り、サブ結晶粒径を10μｍ以下の未再結晶組織とするこ
とを特徴とする靭性の優れたＡｌ−Ｌｉ系合金鍛造材の
製造方法。2. Li: 1.0 to 3.0 wt%, Cu: 1.0 to 3.
0 wt%, Mg: 0.5 to 2.0 wt%, Zr: 0.04 to 0.20 wt%
Al-Li containing Al and the balance Al and unavoidable impurities
After soaking of the alloy-base alloy ingot, hot forging is performed twice or more at a temperature of 340 to 420 ° C. to obtain a cumulative forging ratio of 8 to 16 to obtain a non-recrystallized structure with a sub-crystal grain size of 10 μm or less. A method for producing an Al-Li alloy forged material having excellent toughness, which is characterized by: