JP2951052B2 - Method for producing extruded aluminum alloy for welded structure with improved weld cracking - Google Patents
Method for producing extruded aluminum alloy for welded structure with improved weld crackingInfo
- Publication number
- JP2951052B2 JP2951052B2 JP16592791A JP16592791A JP2951052B2 JP 2951052 B2 JP2951052 B2 JP 2951052B2 JP 16592791 A JP16592791 A JP 16592791A JP 16592791 A JP16592791 A JP 16592791A JP 2951052 B2 JP2951052 B2 JP 2951052B2
- Authority
- JP
- Japan
- Prior art keywords
- extruded material
- liquid nitrogen
- extruded
- extrusion
- die
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Extrusion Of Metal (AREA)
Description
【０００１】[0001]
【産業上の利用分野】この発明は、ＬＮＧを始めとする
タンク構造用材や、ＬＮＧタンカー、漁船用等の船体構
造材として溶接を施されて使用される溶接構造用Ａｌ合
金押出材の製造方法に関し、特に溶接割れを改善した溶
接構造用Ａｌ合金押出材の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum alloy extruded material for a welded structure used by welding as a material for a tank structure such as LNG, a hull structure for an LNG tanker, a fishing boat or the like. More particularly, the present invention relates to a method for manufacturing an extruded aluminum alloy material for welded structures with improved weld cracking.
【０００２】[0002]
【従来の技術及び課題】上記のような用途に用いられる
アルミニウム合金材、特にＡｌ−Ｍｇ系合金押出材は、
軽量であるのみならず耐食性、低温での機械的性質にも
優れているのに加え、溶接性にも優れており、一般的に
は特殊な溶接時以外溶接割れは発生しないと認識されて
いる。2. Description of the Related Art Aluminum alloy materials used for the above applications, particularly extruded Al-Mg alloys, are:
In addition to being lightweight, it has excellent corrosion resistance and mechanical properties at low temperatures, and also has excellent weldability, and it is generally recognized that welding cracks do not occur except during special welding. .
【０００３】しかるに、かかるＡｌ−Ｍｇ系合金押出材
であっても、その製造工程において生じた表面再結晶組
織層の厚みが０．３ｍｍ程度以上にも達して厚すぎる
と、一般的な溶接を施した際に殊に溶接歪みが大きい場
合、熱影響部（ＨＡＺ部）において微少な割れが発生す
ることが発明者らの研究により判明した。[0003] However, even with such an extruded Al-Mg alloy, if the thickness of the surface recrystallized microstructure layer generated in the manufacturing process reaches about 0.3 mm or more and is too thick, general welding can be performed. It has been found by the inventors of the present invention that microcracks occur in the heat-affected zone (HAZ zone) particularly when the welding strain is large when applied.
【０００４】この発明は、かかる事情に鑑みてなされた
ものであって、表面再結晶を抑制することにより、溶接
割れを改善した溶接構造用Ａｌ合金押出材の製作提供を
目的とする。The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an aluminum alloy extruded material for a welded structure having improved welding cracks by suppressing surface recrystallization.
【０００５】[0005]
【課題を解決するための手段】上記目的を達成するため
に、この発明は、Ｍｇ：３．０〜６．０wt％を含有する
Ａｌ−Ｍｇ系合金ビレットを押出ダイスから押出したの
ち、ダイス通過直後に押出材の表面に液体窒素を吹付け
ることを特徴とし、これにより押出材の表面再結晶を抑
制して溶接割れの改善を図ろうというものである。In order to achieve the above-mentioned object, the present invention provides an Al-Mg based alloy billet containing 3.0 to 6.0 wt% of Mg, which is extruded from an extrusion die and passed through the die. Immediately thereafter, liquid nitrogen is sprayed on the surface of the extruded material, thereby suppressing recrystallization of the surface of the extruded material and improving weld cracking.
【０００６】まず、この発明の対象たるＡｌ−Ｍｇ系合
金押出材において、Ｍｇの含有が３．０〜６．０wt％に
規定されるのは、かかる範囲で含有されることによりＡ
ｌ−Ｍｇ系合金が有する耐食性、低温での機械的性質の
良さ、溶接性等の優位性が十分に発揮されるからであ
り、Ｍｇが３．０wt％未満ではそれらの効果に乏しく、
逆に６．０wt％を超えると押出加工性の劣化等を招くか
らである。[0006] First, in the extruded Al-Mg alloy, which is the subject of the present invention, the content of Mg is specified to be 3.0 to 6.0 wt%.
This is because the superiority of the corrosion resistance, mechanical properties at low temperatures, and weldability of the l-Mg-based alloy is sufficiently exhibited. When the Mg content is less than 3.0 wt%, the effects are poor.
Conversely, if it exceeds 6.0% by weight, the extrusion processability is deteriorated.
【０００７】上記Ａｌ−Ｍｇ系合金は、これを常法に従
いビレットに製作し、次いで要すれば均質化処理を実施
したのち押出ダイスにて押出す。押出条件は特に限定さ
れることはなく、通常の押出条件を適宜採用すれば良い
が、この発明では、押出ダイス通過直後に押出材の表面
に液体窒素を直接吹き付ける。これは、ダイス通過直後
に押出材表面を直接液体窒素で急速冷却することで、押
出材の二次的な表面再結晶を防止するためである。ここ
に、押出材表面を冷却するためには水を使用することも
可能であるが、液体窒素は安価で冷却能力が大きいう
え、水を用いた場合該水がダイスベアリングと押出材と
の間に入り込み焼き付きを生じる危険があるため、この
発明では液体窒素を用いることとした。The above-mentioned Al-Mg alloy is manufactured into a billet according to a conventional method, and if necessary, after homogenization, is extruded with an extrusion die. The extrusion conditions are not particularly limited, and ordinary extrusion conditions may be appropriately employed. In the present invention, liquid nitrogen is directly sprayed on the surface of the extruded material immediately after passing through the extrusion die. This is because the surface of the extruded material is rapidly cooled directly with liquid nitrogen immediately after passing through the die to prevent secondary recrystallization of the extruded material. Here, it is possible to use water to cool the surface of the extruded material, but liquid nitrogen is inexpensive and has a large cooling capacity, and when water is used, the water is used between the die bearing and the extruded material. Liquid nitrogen is used in the present invention because of the danger of intrusion and seizure.
【０００８】液体窒素による吹付冷却は、押出材の表面
再結晶抑制の目的のためには、押出材がダイスベアリン
グ通過直後３０秒以内に実施するのが望ましい。３０秒
を越えたのち冷却しても再結晶が進行して、もはや冷却
による再結晶抑制効果がなく表面再結晶組織層が厚くな
り、ひいては熱影響部における溶接割れの発生を防止す
ることができない恐れがあるからである。特に好ましく
はダイスベアリング通過後１５秒以内とするのが良い。The spray cooling with liquid nitrogen is preferably performed within 30 seconds immediately after the extruded material passes through the die bearing for the purpose of suppressing the surface recrystallization of the extruded material. Even after cooling for more than 30 seconds, the recrystallization proceeds even when cooled, and there is no longer any effect of suppressing recrystallization by cooling, the surface recrystallized structure layer becomes thicker, and thus the occurrence of welding cracks in the heat-affected zone cannot be prevented. This is because there is fear. It is particularly preferable to set the time within 15 seconds after passing through the die bearing.
【０００９】液体窒素の供給方法は、特に限定されるこ
とはなく、例えば図１に示すようなものを挙げ得る。即
ち、図１では押出用ダイス（１）とボルスター（４）と
の間に、中央部に押出材通過孔（3a）を有する盤状スペ
ーサ部材（３）を介在させるとともに、該スペーサ部材
（３）の一側面に形成した溝部（５）に液体窒素送給管
（６）を嵌め合わせることにより、該送給管（６）を介
して押出ダイス通過直後の押出材（Ａ）の表面に液体窒
素を吹付けるようにしたものである。なお、図１におい
て、（２）（７）は断熱パッキン部材である。なお、図
１に示す方法では、押出ダイス（１）とボルスター
（４）との間で押出材（Ａ）の表面に液体窒素を吹付け
る構成としているが、液体窒素の吹付けは図示しないプ
ラテン通過時等に行うものとしても良い。The method for supplying liquid nitrogen is not particularly limited, and may be, for example, one shown in FIG. That is, in FIG. 1, a disc-shaped spacer member (3) having an extruded material passage hole (3a) in the center is interposed between the extrusion die (1) and the bolster (4). The liquid nitrogen feed pipe (6) is fitted into the groove (5) formed on one side of the extruded material (A) immediately after passing through the extrusion die through the feed pipe (6). Nitrogen is blown. In FIG. 1, (2) and (7) are heat insulating packing members. In the method shown in FIG. 1, liquid nitrogen is sprayed on the surface of the extruded material (A) between the extrusion die (1) and the bolster (4). It may be performed at the time of passage or the like.
【００１０】押出材表面に吹付ける液体窒素の量として
は、吐出量で０．５〜１０ｋｇＬｉｑＮ2 ／分程度に設
定するのが良い。０．５ｋｇ／分未満の吐出量では冷却
効果に乏しくひいては熱影響部における溶接割れの発生
を防止することができない恐れがあり、１０ｋｇ／分を
越える吐出量では過冷却により押出しが不可能となる恐
れがある。特に好ましくは０．８〜５．０ｋｇＬｉｑＮ
2 ／分の吐出量に設定するのが良い。また、液体窒素の
吐出量は、押出材の形状、押出速度、押出機の構造等に
よって変えても良い。例えば、厚さ６ｍｍのフラットバ
ーを押出速度３〜５ｍ／分で押出すとともに、図１に示
す装置で液体窒素を吹付ける場合は、液体窒素の吐出量
を０．８〜１．２ｋｇ／分程度とすれば良く、厚さ１２
ｍｍのＴ形材を押出速度１．５〜２ｍ／分で押出すとと
もに、プラテン内で液体窒素を吹付ける場合は、吐出量
を１．０〜３．５ｋｇ／分程度とすれば良く、厚さ２２
ｍｍのＴ形材を押出速度１．５〜２ｍ／分で押出すとと
もに、プラテン内で液体窒素を吹付ける場合は、吐出量
を１．５〜４．５ｋｇ／分程度とすれば良い。The amount of liquid nitrogen sprayed on the surface of the extruded material is preferably set to about 0.5 to 10 kg LiqN 2 / min in terms of discharge rate. If the discharge rate is less than 0.5 kg / min, the cooling effect is poor, and it may not be possible to prevent the occurrence of welding cracks in the heat-affected zone. If the discharge rate exceeds 10 kg / min, extrusion becomes impossible due to supercooling. There is fear. Particularly preferably, 0.8 to 5.0 kg LiqN
It is better to set the discharge rate to 2 / min. Further, the discharge amount of liquid nitrogen may be changed depending on the shape of the extruded material, the extrusion speed, the structure of the extruder, and the like. For example, when a flat bar having a thickness of 6 mm is extruded at an extrusion speed of 3 to 5 m / min and liquid nitrogen is sprayed by the apparatus shown in FIG. 1, the discharge rate of liquid nitrogen is set to 0.8 to 1.2 kg / min. About 12 mm thick
mm T-shaped material is extruded at an extrusion speed of 1.5 to 2 m / min, and when liquid nitrogen is sprayed in the platen, the discharge rate may be about 1.0 to 3.5 kg / min. Sa22
mm T-shaped material is extruded at an extrusion speed of 1.5 to 2 m / min, and when liquid nitrogen is sprayed in the platen, the discharge rate may be about 1.5 to 4.5 kg / min.
【００１１】ところで、上記の押出において、０．５ｍ
／分以下の製品速度で押出したり、あるいは押出に際し
てのビレット加熱温度を低く設定する等によっても、押
出材表面の再結晶を抑制することは可能である。しか
し、押出速度を低くする方法では歩留生産性の低下を招
く欠点を派生する。またビレットの加熱温度を低くする
方法ではビレット全長を短くせざるを得ず、同じく生産
効率が良くないという欠点を派生する。これに対し、本
願発明のように、ダイス通過直後に押出材表面に液体窒
素を吹付ける場合には、押出速度の低下やビレットの短
尺化を要することなく、通常の押出と同様の条件を採択
しつつ、押出材表面の再結晶組織層の厚さを０．０５〜
０．１５ｍｍ程度以下に抑制したものとなしうる。In the above extrusion, 0.5 m
It is also possible to suppress recrystallization of the surface of the extruded material by extruding at a product speed of not more than / min or setting a low billet heating temperature during extrusion. However, the method of lowering the extrusion speed has a disadvantage that the yield productivity is reduced. In addition, in the method of lowering the billet heating temperature, the total length of the billet must be shortened, which also has the disadvantage that the production efficiency is not good. On the other hand, when liquid nitrogen is sprayed on the surface of the extruded material immediately after passing through the die as in the present invention, the same conditions as in the normal extrusion are adopted without reducing the extrusion speed or shortening the billet. While the thickness of the recrystallized structure layer on the surface of the extruded material is 0.05 to
The thickness can be suppressed to about 0.15 mm or less.
【００１２】[0012]
【作用】ダイス通過直後に押出材の表面に液体窒素を吹
付けるから、押出材表面が急冷され、押出後の押出材の
表面再結晶が抑制されたものとなり、溶接時における熱
影響部の溶接割れが抑制される。[Function] Since liquid nitrogen is sprayed on the surface of the extruded material immediately after passing through the die, the surface of the extruded material is rapidly cooled, and the surface recrystallization of the extruded material after extrusion is suppressed. Cracks are suppressed.
【００１３】[0013]
【実施例】Ｍｇ：４．５wt％を含有するＡ５０８３合金
を用いて製作した２個のビレットにつき、同一条件で均
質化処理を実施した。EXAMPLE Homogenization treatment was performed on two billets manufactured using an A5083 alloy containing 4.5 wt% of Mg under the same conditions.
【００１４】次に、一方のビレットについてはビレット
加熱温度：４８０℃、押出製品速度：３．２ｍ／分の押
出条件で厚さ６ｍｍのフラットバーに押出すとともに、
ダイス通過直後に押出材の表面に液体窒素を吹付けて急
冷した。このときの押出材の温度（プラテン出口の温
度）は４２０〜４５０℃であった。この押出材の表面再
結晶組織層の厚さを測定したところ約０．１ｍｍであっ
た。Next, one of the billets is extruded into a flat bar having a thickness of 6 mm at a billet heating temperature of 480 ° C. and an extrusion product speed of 3.2 m / min.
Immediately after passing through the die, the surface of the extruded material was sprayed with liquid nitrogen and rapidly cooled. At this time, the temperature of the extruded material (the temperature at the exit of the platen) was 420 to 450 ° C. When the thickness of the surface recrystallized structure layer of this extruded material was measured, it was about 0.1 mm.
【００１５】また、他方のビレットについては、ビレッ
ト加熱温度：４８０℃、押出製品速度：２．６ｍ／分の
押出条件で厚さ６ｍｍのフラットバーに押出した。ダイ
ス通過直後における液体窒素の吹付けによる冷却は行わ
なかった。この押出材の温度は５１０〜５２０℃であっ
た。また、この押出材の表面再結晶組織層の厚さを測定
したところ約０．５ｍｍであった。The other billet was extruded into a flat bar having a thickness of 6 mm at a billet heating temperature of 480 ° C. and an extrusion product speed of 2.6 m / min. Cooling by spraying liquid nitrogen immediately after passing through the die was not performed. The temperature of this extruded material was 510-520 ° C. The thickness of the surface recrystallized structure layer of this extruded material was measured to be about 0.5 mm.
【００１６】次に、各押出材につき、同一条件でＭＩＧ
溶接による衝き合わせ溶接を行ったところ、ダイス通過
直後に液体窒素の吹付けによる冷却を行った本発明実施
品については、溶接割れの発生は全く認められなかった
のに対し、ダイス通過直後の冷却操作を行わなかった比
較品については、熱影響部に微細な割れが発生してい
た。Next, for each extruded material, MIG was performed under the same conditions.
When butt welding was performed by welding, the product of the present invention, which was cooled by spraying liquid nitrogen immediately after passing through the die, did not show any occurrence of welding cracks, whereas the product immediately after passing through the die was cooled. For the comparative product that was not operated, fine cracks occurred in the heat-affected zone.
【００１７】従って、本発明によれば、表面再結晶を抑
制しえて溶接割れを改善しうることを確認しえた。Therefore, it has been confirmed that according to the present invention, surface recrystallization can be suppressed and welding cracks can be improved.
【００１８】[0018]
【発明の効果】この発明は、上述の次第で、Ｍｇ：３．
０〜６．０wt％を含有するＡｌ−Ｍｇ系合金ビレットを
押出ダイスから押出したのち、ダイス通過直後に押出材
の表面に液体窒素を吹付けることを特徴とするものであ
るから、ダイス通過直後の押出材の表面が急冷される結
果、表面再結晶を抑制しえて押出材の表面再結晶組織層
の厚さを薄くすることができる。このため表面再結晶組
織層の厚さが厚いために従来生じていた熱影響部におけ
る溶接割れをなくすことができ、Ａｌ−Ｍｇ系合金押出
材の有する溶接構造材としての利点を存分に発揮させる
ことができる。しかも、ダイス通過直後に押出材の表面
に液体窒素を吹付けることで、押出材の表面再結晶を抑
制するものであるから、押出速度の低下やビレット長さ
の短尺化を必要とすることなく押出を行うことができ、
歩留生産性の低下を回避することができる。According to the present invention, as described above, Mg: 3.
After extruding an Al-Mg based alloy billet containing 0 to 6.0 wt% from an extrusion die, liquid nitrogen is sprayed on the surface of the extruded material immediately after passing through the die. As a result of the rapid cooling of the surface of the extruded material, the surface recrystallization can be suppressed and the thickness of the surface recrystallized structure layer of the extruded material can be reduced. For this reason, welding cracks in the heat-affected zone, which had conventionally occurred because the thickness of the surface recrystallized structure layer was large, can be eliminated, and the advantages as a welded structural material of the extruded Al-Mg-based alloy material can be fully exhibited. Can be done. Moreover, since liquid nitrogen is sprayed on the surface of the extruded material immediately after passing through the die, the recrystallization of the surface of the extruded material is suppressed. Extrusion can be performed,
A decrease in yield productivity can be avoided.
【図１】この発明を実施する一例としての押出装置の断
面図である。FIG. 1 is a cross-sectional view of an extruder as an example for embodying the present invention.
１…押出用ダイス ６…液体窒素送給管 1. Extrusion dies 6. Liquid nitrogen feed pipe
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平２−127916（ＪＰ，Ａ) 特公 昭47−4783（ＪＰ，Ｂ１) (58)調査した分野(Int.Cl.6，ＤＢ名) B21C 29/00 B21C 23/00 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-127916 (JP, A) JP-B-47-4873 (JP, B1) (58) Fields investigated (Int. Cl. 6 , DB name) B21C 29/00 B21C 23/00
Claims (1)
ｌ−Ｍｇ系合金ビレットを押出ダイスから押出したの
ち、ダイス通過直後に押出材の表面に液体窒素を吹付け
ることを特徴とする溶接割れを改善した溶接構造用Ａｌ
合金押出材の製造方法。1. A containing Mg: 3.0 to 6.0 wt%.
After the l-Mg alloy billet is extruded from the extrusion die, liquid nitrogen is sprayed on the surface of the extruded material immediately after passing through the die, and the Al for welded structure has improved weld cracking.
Manufacturing method of alloy extruded material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16592791A JP2951052B2 (en) | 1991-07-05 | 1991-07-05 | Method for producing extruded aluminum alloy for welded structure with improved weld cracking |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16592791A JP2951052B2 (en) | 1991-07-05 | 1991-07-05 | Method for producing extruded aluminum alloy for welded structure with improved weld cracking |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH057927A JPH057927A (en) | 1993-01-19 |
| JP2951052B2 true JP2951052B2 (en) | 1999-09-20 |
Family
ID=15821657
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16592791A Expired - Lifetime JP2951052B2 (en) | 1991-07-05 | 1991-07-05 | Method for producing extruded aluminum alloy for welded structure with improved weld cracking |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2951052B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5956806B2 (en) * | 2012-04-03 | 2016-07-27 | 三協立山株式会社 | Method for producing magnesium alloy extruded material |
| CN107429337B (en) * | 2015-04-03 | 2019-06-07 | 株式会社Uacj | The aluminium-alloy pipe and its manufacturing method of corrosion resistance and excellent in workability |
-
1991
- 1991-07-05 JP JP16592791A patent/JP2951052B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH057927A (en) | 1993-01-19 |
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