JPH0724583A - Manufacture of pressure vessel and material used therefor - Google Patents

Abstract

PURPOSE:To prevent the generation of defects such as cracks and blowholes at weld zone and to improve the reliability in forming a pressure vessel by joining a plurality of split bodies made of Al alloy material by the electron beam welding. CONSTITUTION:An upper split body 12 and a lower split body 14 are prepared by using Al alloy of a composition consisting of, by weight, 0.8-1.2% Si, 0.5-1.0% Mn, 0.4-0.8% Mg, 0.1-0.2% Ti with the ratio of the content of Mg to that of Si (Mg/Si) being <=0.8, and the balance Al with inevitable impurities, and these split bodies are joined by the electron beam welding to form a pressure vessel body 10.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a pressure vessel made of an aluminum (Al) alloy by using electron beam welding, and an Al excellent in electron beam weldability used for manufacturing such a pressure vessel. It relates to alloy materials.

[0002]

BACKGROUND ART Electron beam welding is a method of irradiating an object with electrons accelerated in a vacuum, melting the base metal itself by its thermal energy, and welding, unlike a general arc welding method. It has the great feature that no filler material is required. As a result, they enjoy the advantages of (1) deeper penetration, (2) less heat effect, (3) less heat distortion, and (4) no gas pollution. In addition, this electron beam welding method is said to have better weld quality than other welding methods, and requires high welding reliability for nuclear equipment, aircraft, transportation equipment such as automobiles. In many fields, it is often used for welding when manufacturing pressure vessels such as accumulators. In particular, when manufacturing an accumulator in which a diaphragm is housed, the adoption of such an electron beam welding method is extremely advantageous in that the thermal influence on the diaphragm can be reduced or avoided.

By the way, a pressure vessel manufactured by electron beam welding has conventionally been made of a steel material.
In recent years, there has been an extremely high need for Al in order to reduce the weight. However, although there is no track record of using Al material in Japan, and there is a track record of manufacturing with Al material abroad, but there is no mass production record, and there are many technically unclear factors (for example, material and welding conditions). , Welding quality etc.). Moreover, in general, in the case of Al material, welding defects such as cracks and blowholes are likely to occur in the welded portion depending on the material and welding conditions, and even in electron beam welding, local strain occurs due to rapid heating and quenching. As a result, cracks may occur, or steam generated during melting may remain, resulting in blowholes and similar welding defects. Therefore, there are still many problems in adopting the electron beam welding method for welding Al materials, and they have not been put into practical use.

[0004]

The present invention has been made in view of such circumstances, and the problem to be solved is to use Al in a pressure vessel and adopt an electron beam welding method in manufacturing the pressure vessel. To be able to do so. Further, for that reason, it is to develop an Al material excellent in electron beam weldability and free from defects such as cracks and blowholes in the welded portion.

[0005]

In order to solve the above problems, the present inventors have developed a Al material excellent in electron beam weldability based on JIS-A-6061 alloy, which has high versatility, to 6000. The optimization of the contents of Si and Mg in the alloy component, which is the main component of the base alloy, was conducted in detail, and as a result, the following findings were obtained. That is, since (i) Si has the effect of increasing the fluidity of the molten metal and is effective in improving the crack resistance, it is preferable to add a certain amount of (i) Si. (ii) On the other hand, since Mg becomes vapor and tends to remain as blowholes, it is better to add Mg to some extent. (iii) Further, Ti, which is a characteristic improving element, has an effect of refining crystal grains, and when added in a predetermined amount, has an effect of preventing cracking.

The present invention has been completed as a result of further studies based on these findings. That is, the gist of the present invention is (a) on a weight basis,
Si: 0.8-1.2%, Mn: 0.5-1.0%, M
g: 0.4 to 0.8% and Ti: 0.1 to 0.2%, and the content ratio of Mg and Si (Mg / Si) is 0.8.
The step of preparing a plurality of divided bodies for providing a target pressure vessel by using an Al alloy having the following composition and the balance being Al and unavoidable impurities, and (b) electron beam forming the plurality of divided bodies. And a step of forming the desired pressure vessel by joining them by welding.

Further, according to the present invention, the Si: 0.
8 to 1.2%, Mn: 0.5 to 1.0%, Mg: 0.4
.About.0.8% and Ti: 0.1 to 0.2%, and
An Al alloy material for manufacturing a pressure vessel having a composition in which the content ratio of Mg and Si (Mg / Si) is 0.8 or less and the balance is Al and inevitable impurities is also included in the gist.

[0008]

[Specific Structure] By the way, in the present invention, the Al alloy material used as the material of the divided body includes Si and M.
Each of n, Mg, and Ti is contained in a predetermined ratio. Among these alloy components, Si is an element effective for securing strength and improving crack resistance, and it is necessary to contain Si in a proportion of 0.8% or more, but if it increases, it decreases toughness. It has to be contained up to 1.2%. Further, Mn is an element that enhances mechanical properties and is required to be 0.5% or more. However, if it exceeds 1.0%, the effect is not improved and the cost increases, so 1.0% is the upper limit. As a result, it is included. Furthermore,
In order to secure the strength and the weld penetration depth, it is necessary to contain 0.4% or more of Mg, but since it easily evaporates during welding and remains as blowholes inside, 0.8% is the upper limit. , Contained. And, Ti has an effect of refining crystal grains, and is 0.1%.
If added in the above amount, it is effective in preventing cracking, but if it is too much, problems occur in dispersibility and uniform quality is not obtained. Therefore, from the viewpoint of manufacturing quality, 0.2% is made the upper limit and it is contained.

Further, in such an Al alloy material, Si
And Mg are the main components to form Mg ₂ Si and secure the strength. It is known that the balance composition of Mg and Si is Mg: Si = 1.73: 1. There is. In addition, the content ratio of Mg and Si (Mg / S
As a result of investigating i) as well, it was found that welding defects are eliminated by adding excess Si to the above balance composition. Therefore, in the present invention,
The content ratio of Mg and Si (Mg / Si) is 0.8 or less.

The balance excluding the above alloy components is composed of Al and unavoidable impurities. Among various known impurities that are inevitably mixed in Al, Fe is However, the ductility and impact value decrease as the amount increases, so 0.4% or less is desirable. Also, Cu
In the range up to 3%, the higher the ratio, the higher the crack susceptibility, so it is desirable to set it to 0.1% or less. Furthermore, Cr
Is effective in improving the stress corrosion cracking resistance, but if it increases, it deteriorates the hardenability, so it is desirable to set it to 0.25% or less. Furthermore, Zn is likely to evaporate during welding and remain as a blowhole. Therefore, 0.2% or less is desirable.

In the Al alloy material having such a composition, the content of Si and the content of Mg are specified, respectively, and the content ratio of Si and Mg is narrowed down to an appropriate value. Is added, so that the component design is excellent in electron beam weldability, and a small amount of Mn is added to improve mechanical strength. Therefore, when welding such an Al alloy material, the electron beam welding method can be adopted, and the occurrence of defects such as cracks and blowholes in the welded portion is effectively prevented, and high reliability is secured. It is possible.

Thus, in the method for manufacturing a pressure vessel according to the present invention, first, a plurality of divided bodies for providing a desired pressure vessel are prepared by using the Al alloy material having the above-mentioned composition. , Then, by joining the plurality of divided bodies by electron beam welding,
The target pressure vessel is obtained.

More specifically, an accumulator for a vehicle, which is an example of a pressure vessel, will be described as an example. First, in the vehicle accumulator shown in FIG. 1, 10 is a pressure vessel body having a substantially spherical shape, and is composed of an upper divided body 12 and a lower divided body 14. Each of the upper and lower divided bodies 12, 14 is formed and prepared by, for example, press molding using the Al alloy material having excellent electron beam weldability as described above. Further, on the inner peripheral surface of the opening of the lower divided body 14,
A ring-shaped mounting member 16 is caulked and fixed, so that the membrane diaphragm 18 is mounted in a state where the peripheral edge portion is sandwiched between the mounting member 16 and the lower divided body 14, and the diaphragm 18 is attached. An oil chamber 20 is formed between the wall portion of the lower divided body 14 and the lower divided body 14.

Then, the upper and lower divided bodies 12, 14 are assembled in a state where their openings are abutted with each other, and the assembled parts are integrally joined by a usual electron beam welding method, whereby the pressure vessel is formed. The main body 10 is formed. Therefore, in the production of such a pressure vessel main body 10, which is a feature of electron beam welding, (1) deep penetration can be obtained, (2) little heat influence, (3) little distortion due to heat, 4) The advantage that there is no gas pollution can be enjoyed. In addition, the upper and lower split bodies 12,
Since 14 has an excellent electron beam weldability in terms of material, it is possible to favorably prevent the occurrence of cracks and blowholes in the welded portion 30, and ensure excellent reliability.

Inside the pressure vessel body 10, a gas chamber 22 is formed between the diaphragm 18 and the wall portion of the upper divided body 12. And
A gas plug 24 is attached to a wall portion of the upper divided body 12 so as to communicate with the gas chamber 22, and an oil port 26 is provided at a wall portion of the lower divided body 14 so as to communicate with the oil chamber 20. By attaching the provided plug 28, a desired accumulator (pressure vessel) is formed. As described above, according to the method of the present invention, a pressure vessel made of an Al alloy can be manufactured by electron beam welding, and a lightweight pressure vessel having high welding reliability can be obtained.

[0016]

EXAMPLES Some examples of the present invention will be shown below to clarify the present invention in more detail. However, the present invention is not limited by the description of such examples. Needless to say, it is not something to receive. Further, in addition to the following specific examples, in addition to the following embodiments, the present invention includes various modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention.
It should be understood that modifications, improvements, etc. may be made.

First, in the proportions shown in Table 1 below, Si, Mn,
Various Al alloy materials containing Mg and Ti (alloy No. 1
21) was prepared, a pair of test materials for welding was prepared from each material, and the pair of test materials were welded by electron beam welding. The main conditions for electron beam welding are acceleration voltage: 60
kV, beam current: 37 mA, welding speed: 14 mm / sec
Met. Then, after the welding, the welded portion of each test material was cut, and the occurrence of cracks and blowholes in the welded portion was observed, and the results were evaluated as follows and combined with Table 1 below. Showed. ⊚: No defect ○: Defect size is 0.1 mm or less Δ: Defect size is 1 mm or less ×: Defect size exceeds 1 mm

Further, the toughness of each Al alloy material is determined by JIS-
The measurement was carried out in accordance with the metal material impact test method of Z-2242, and the result was evaluated as ◯ (practical range) or × (impractical), and is also shown in Table 1 below.

[0019]

[Table 1]

As is clear from the results shown in Table 1 above, S
Alloys in which the contents of i, Mn, Mg, and Ti are all within the regulations of the present invention and the Mg / Si component ratio is 0.8 or less (alloy No. 8, 10, 13 to 14, 16 to 18) ) Then,
Almost no cracks or blowhole defects in the weld,
It can be seen that it has high reliability and has excellent toughness.

On the other hand, alloys having a content of Si, Mn, Mg or Ti outside the prescribed range of the present invention or having a Mg / Si component ratio exceeding 0.8 (alloy Nos. 1 to 7,
In Nos. 9, 15, 19 to 21), cracks and blowhole defects occur in the welded portion, resulting in low reliability. Also,
Alloys containing too much Si (Alloy Nos. 11 to 12) had low toughness and were not suitable for practical use.

FIG. 2 is a graph showing the relationship between the component specifications of these alloys and the occurrence of welding defects, based on the Si content, the Mg content and the Mg / Si component ratio. ○ indicates no welding defects (Cracks and blowholes are evaluated as ◎ or ○ in Table 1), ● indicates welding defects (Cracks or blowholes are evaluated as Δ or × in Table 1), and △ indicates no welding defects. Other properties (toughness, etc.) that cannot be used practically are shown.

[0023]

As is apparent from the above description, in the present invention, the predetermined Al having improved electron beam weldability is used.
By preparing a plurality of split bodies using an alloy material and joining the split bodies by an electron beam welding method,
The desired pressure vessel is manufactured. Therefore, based on the characteristics of the Al alloy material, the occurrence of welding defects due to electron beam welding can be favorably prevented, and the reliability can be improved. Then, cracks in welds and defects such as blow holes can be reduced to less than half. Furthermore, by electron beam welding, it is possible to manufacture a pressure vessel made of Al alloy, and it is possible to provide a lightweight pressure vessel with high welding reliability, which makes it possible to meet the needs for weight reduction. It will be.

[Brief description of drawings]

FIG. 1 is a half cross-sectional explanatory view showing a vehicle accumulator as an example of a pressure vessel manufactured according to the present invention.

FIG. 2 is a graph showing the relationship between the composition of each alloy used in the examples and the occurrence of welding defects.

[Explanation of symbols]

 10 Pressure Vessel Main Body 12 Upper Divided Body 14 Lower Divided Body 16 Mounting Bracket 18 Diaphragm 20 Oil Chamber 22 Gas Chamber 30 Welding Part

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location B23K 103: 10 (72) Inventor Koichi Maeda 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Incorporated (72) Inventor Shinichi Matsuda 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industry Co., Ltd.

Claims (2)

[Claims] 1. Si: 0.8 to 1.2% by weight,
Mn: 0.5 to 1.0%, Mg: 0.4 to 0.8% and Ti: 0.1 to 0.2%, and the content ratio of Mg and Si (Mg / Si) is 0. 8 or less and the balance is A
a step of preparing a plurality of divided bodies for providing a desired pressure vessel by using an Al alloy having a composition of 1 and unavoidable impurities, and joining the plurality of divided bodies by electron beam welding to obtain the desired pressure. And a step of forming a container. 2. Si: 0.8 to 1.2% by weight,
Mn: 0.5 to 1.0%, Mg: 0.4 to 0.8% and Ti: 0.1 to 0.2%, and the content ratio of Mg and Si (Mg / Si) is 0. 8 or less and the balance is A
The Al alloy material for manufacturing a pressure vessel according to claim 1, having a composition consisting of 1 and inevitable impurities.