DE2503046A1 - PROCESS FOR WELDING THICK ALUMINUM AND ALUMINUM ALLOYS PLATES - Google Patents

Description

G 49 757

KOBE STEEL, Ltd., 3-18, 1-Chome, Wakinohama-Cho, Fukiai-Ku, KOBE / JAPAN

Process for welding together thick plates made of aluminum and aluminum alloys

The invention relates to arc welding with non-consumable electrode, which is hereinafter referred to as TIG welding _# and particularly to a method for butt welding of plates made of aluminum and aluminum alloys with narrow or narrower weld groove by applying a direct current and protective gas, which with high efficiency, a good weld is to be generated, the width of which is greater in the inner area than in the outer part.

Corresponding to the increasing demand for welding thick plates, various welding processes that work with high efficiency have recently been used, suggested. Most of these methods of butt welding use I-shaped or narrower V-shaped

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Welding grooves are MIG welding processes, i.e. working with a melting electrode under protective gas Welding process. The electrode is swept through with a small pendulum movement or twice or several times the welding groove or there is a control of the welding current instead of errors such as lack of Penetration generated on both side walls of the welding groove or in the border areas between the individual ones To prevent layers of weld seam. Nevertheless, welding defects often occur in these processes. aside from that the necessary welding device is very complicated, so that it is difficult to practice these methods to be used for high quality welding. Aluminum alloys are widely used as a low temperature enduring material for transportation purposes or used for liquid gas containers. The material is used in the form of thick plates that must be welded together. It is necessary that the weld seams at high efficiency consistently and flawlessly quality through and through.

When welding aluminum alloys, many difficulties arise because of the physical and metallurgical properties of these alloys that are not found when welding ferrous materials available.

Generally speaking, both TIG welding can be used with a non-consumable electrode as well as MIG welding with a consumable electrode for Use aluminum alloy welding. Although TIG welding is compared to MIG welding with respect to the Arc stability and the quality of the welded

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seams is far superior, there are also disadvantages to this process, such as when welding Aluminum used according to the TIG process alternating current, on which a current of high frequency is superimposed. This way of working is used because Application of direct current in conjunction with a negative electrode is impossible on the Plate surface to remove oxide film formed while the electrode melts when it is positive. Therefore, the welding current must be greatly reduced. If you use high AC currents, it melts Electrode also off. Therefore, the usual TIG welding must be carried out with a low electric current so that effective welding with great penetration depth cannot be achieved.

Achieved positive polarity when welding with a negative welding rod or negative electrode and plates a good penetration and a good depth effect of the weld with low consumption of the electrode. As mentioned above, however, one cannot expect that the formed on the surfaces to be connected Oxide film is removed, so that the weld seam is often bad and the weld bead, for example throws.

To overcome these problems it has been found that, when the electrode has a rounded or flat end and very close to the one to be welded together Plates is arranged and suppressed an excessive distribution of the arc and an arc concentration on the central part of the arc prevents the arc distribution on the plate is approximately equal to the cross-sectional area of the electrode end, with the weld pool not or

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is practically not moved even when a high welding current is applied. Melting the plate progresses in parallel with the arc and the shape of the weld metal cross-section is such that the The penetration depth is sufficiently large compared to the width of the weld bead. That is why it is in the case of welding possible with negative electrode, with stable arc and without the risk of wrinkles or other binding defects of the weld bead against the plate with deep penetration to be welded. Nevertheless, it is difficult to enter the metal to be deposited into a welding groove of a certain width. There a Removal of the oxide film formed when welding with negative electrode cannot be expected, one must Be aware that there are oxide inclusions in the deposited metal and that the penetration between the deposited metal and the plates to be welded together is insufficient when a filler wire as in usual TIG welding process is inserted. Because The short length of the arc also makes it difficult to insert a filler wire into the crater formed by the arc.

On the other hand, MIG welding is TIG welding Inferior in terms of arc stability and welding quality, in terms of welding speed however, consider. The MIG welding process is therefore used in practice. It is indeed possible to use a high electric current in MIG welding compared to TIG welding, however the disadvantage that a deep penetration or burn-in in the plates to be welded itself with a high Welding current cannot be achieved, especially when welding vertically, or overhead horizontal welding, because of the special

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Properties of aluminum alloys. In other words, this means that the melting point of pure aluminum is about 66o ⁰ C, while the melting point of iron at about '153O ⁰ CΓ-inil the density or specific gravity of aluminum is about one third as large as that of iron Therefore, the amount of metal deposited is much greater in aluminum alloys than in iron when the same welding current is used, which prevents the arc flame from reaching the plate to be welded, so that this plate is not heated sufficiently. In addition, the thermal conductivity of aluminum is too high, so that the heat introduced into the welding zone is quickly dissipated therefrom without improving the melting effect and penetration. If the welding current is increased, the amount of deposited metal is also increased, instead of increasing the penetration or penetration into the plate to be welded, so that penetration becomes insufficient and flaking occurs. In addition, aluminum is a very active element, so that a perfect shielding gas cover is necessary to achieve a complete weld.

Because of these problems, the possible shapes of the weld groove are limited, i.e. the tip angle of a V-shaped welding groove must be used when using MIG welding be large enough, which inevitably is the cross-sectional area the weld groove is enlarged, so that the amount of deposited metal must be greater. At the Welding aluminum alloys, a pendulum motion with a large deflection leads to an insufficient Penetration into the plate and due to microcracks to one Insufficient weld seam strength, which can be seen on

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the eutectic melting of aluminum alloys is due. Accordingly, there must be a pendulum motion Avoid grounding the electrode. So you have practically straight welding beads or can only place weld beads generated with a slight pendulum movement, so that a welding process with high efficiency for welding thick plates made of aluminum or aluminum alloys so far has not been developed.

As already mentioned above, both the well-known TIG welding process and the well-known MIG welding processes associated numerous problems, so that one has a highly efficient welding up to now Not yet for welding thick plates or other pieces of aluminum and aluminum alloys together has applied. In conventional welding of the type indicated in FIG. 1, the width is the Weld seam on the surface of the same large and decreases with increasing depth of the weld bead. At the Welding of parts made of aluminum alloy with a narrow welding gap or narrow welding groove, As shown in Fig. 2, a filler metal is first entered into the welding groove and then after the TIG welding process welded. However, this has the disadvantage that there is not enough in the corners of the welding groove In order to overcome this disadvantage, one can increase the voltage or the welding current, so that there is sufficient penetration also in the corners of the weld groove, but this occurs Undercuts, as Fig. 3 shows.

The TIG-Schwelßen with negative electrode is for example in "Welding Journal", May 1971, pages 332 bis. However, it is not known that the TIG-

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Welding apply after a filler metal in a narrow weld groove between very thick plates has been entered.

In U.S. Patent 3,825,712 there is a TIG eye welding process in connection with a narrow welding groove disclosed, but it is difficult to use the filler wire introduce under the arc in all welding positions, as already explained above.

The object of the invention is to address the disadvantages the known welding process for welding together of thick sheets of aluminum and aluminum alloys to overcome and create the possibility of such objects when using a narrow Welding groove and when using a high welding current to be welded together with the TIG welding process in such a way that a thoroughly satisfactory weld seam arises, which has a greater width in the inner area than on the surface.

To solve this problem is to butt welding of more than 20 mm thick plates made of aluminum or

A1 - T- ^ J-Ji-, oun Λ ^βίη method aluminum alloys with narrow welding groove / proposed, which is carried out without melting the Eleltrode and consists in first entering a filler material into the welding groove, then a direct current of more than 300 A between the non-melting electrode, which does not have a sharp-edged end, and the plates to be welded together so that the welding electrode has negative polarity, an arc between 0.5 and 5 mm in length being maintained and a protective gas consisting of at least 50% helium , is used.

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With the invention it is possible, using of the TIG welding process with high welding current to obtain a perfect metal weld without that there are defects such as micro-cracks in the weld seam,

According to a preferred embodiment of the invention the filler material is entered into the weld seam by MIG welding and then through with a high StiOm performed TIG welding melted again.

On the other hand, it is also possible to insert the filler material mechanically into the welding groove and do the same then melt or close again using a high welding current by TIG welding melt.

If the filler material is introduced into the welding groove by MIG welding and then melted again by TIG welding, this method of operation can be repeated several times according to the invention.

According to yet another characteristic of the invention, a double protective layer can be provided for TIG welding, wherein at least the inner protective gas layer contains at least 50% helium.

According to a sixth feature of the invention, the angle of the V-shaped weld seam is that of aluminum or aluminum alloy plates less than 30 °.

According to a seventh feature of the invention, the filler material is in a thickness of 3 to 20 mm and one

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maximum width from one to three times the diameter the non-consumable electrode is filled into the welding groove.

According to an eighth feature of the invention, the Electrode straight along the welding groove *

According to a ninth feature of the invention, the Non-consumable electrode with approximately right angles to the advancing direction of the weld seam Pendulum movements guided along the welding groove.

According to a tenth feature of the invention, the Oscillation frequency of the electrode 10 to 100 full oscillations per minute.

According to an eleventh feature of the invention, the pendulum deflections are less than 10 mm.

According to a twelfth feature of the invention, when combined MIG welding and TIG welding more than two non-consumable electrodes can be used, the distance from one electrode to each following electrode is 30 to 200 mm.

According to a thirteenth aspect of the invention, the time between the point in time at which a Electrode passes a certain point of the weld, and the time at which the following electrode same point happened, 4 to 60 seconds.

According to a fourteenth feature of the invention, the parts of the weld groove in which a good melting and

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Burn-in not achieved with the aid of MIC welding can be carried out by under, high current TIG welding, which results in a deep penetration or penetration in these parts achieved.

According to a fifteenth feature of the invention, welding is carried out in the vertical direction.

According to a sixteenth aspect of the invention welded vertically in an inclined position.

According to a seventeenth aspect of the invention, a non-consumable electrode is used in the vertical Welding or, in vertical welding, moved downward in an inclined position.

According to an eighteenth feature of the invention, the MIG welding provided for introducing the filler material upwards and the subsequent TIG welding downwards, both in the vertical Welding or in the case of vertical welding in an inclined position.

According to a nineteenth aspect of the invention, vertical welding or vertical welding in an inclined position the MIG welding upwards and the subsequent TIG welding upwards as well carried out.

According to a twentieth feature of the invention, welding is carried out in the horizontal direction.

According to a twenty-first feature of the invention

ge
welded in the horizontal direction in the inclined position.

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According to a twenty-second feature of the invention, there is also when MIG welding and TIG welding are combined, welded in the horizontal direction.

According to a twenty-third feature of the invention, MIG welding and TIG welding are combined welded in the horizontal direction in an inclined position.

The invention is further explained below with reference to the drawing, namely shows

1 shows a cross section through a conventional weld seam, which tapers with increasing depth,

Fig. 2 cross-sections through a narrow weld seam between two thick plates, which according to known Procedure was generated,

3 shows cross-sections similar to FIG. 2, showing another weld seam produced by known methods demonstrate,

4 shows a cross section through a weld seam produced according to the invention,

Fig. 5a is a view of the tip of a prior art

TIG welding processes used non-consumable Electrode,

Fig. 5b and 5c are views of tips of for the present Invention used non-consumable electrodes,

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6 shows cross-sections from which it can be seen how the welding according to the invention is carried out will,

7 shows cross-sections through filling materials with characteristics adapted to the method according to the invention To shape,

8 shows cross-sections from which further details of the method according to the invention can be seen are and

9 shows still other cross-sections which demonstrate the welding method according to the invention.

According to the invention, a weld seam or weld bead is to be produced, the width b of which is inside Part of the weld groove is larger than the width a on the surface of the SG weld groove or the weld bead, as Fig. 4 shows. This makes it possible with high effectiveness and deep penetration or deep penetration in platai made of aluminum or aluminum alloys starting from a shell or to weld narrow welding groove with almost parallel side walls.

To get that stable deep penetration or that uniform deep penetration, it is desirable that the current density of the electrode increases

2 p

10 to 50 A / mm is maintained. Below 10 A / mm you can insufficient penetration or insufficient penetration with regard to the width of the weld seam, so that at such a current density the weld can become unstable. At a current density

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above 50 A / mm, the arc used for welding becomes too strong to use a flat mirror or maintain a flat surface of the melt so that the molten metal will leak and drip down can, especially when welding in the vertical and horizontal directions. A welding electrode with sharp tip, as in Pig. 5a, leads to a Concentration or bundling of the arc and is also undesirable for the present invention. Rather, the end of the TIG welding used electrode be flat or rounded, like shown in Figures 5b and 5c.

According to the invention, direct current is greater than 300 A are used, the negative potential being applied to the electrode and the positive potential being applied to the electrode to be welded Plates is laid. It is important to keep the non-consumable electrode close to the electrode to be welded To hold plates. Iris in particular should be the calibration of the plates on which the arc outgoing force acts, be approximately equal to the cross-sectional area of the non-consumable electrode. Under Under these circumstances, extremely good welding results can be achieved that cannot be achieved with conventional welding processes can be reached. It is believed that the surface of the molten bath or melt because of the short length of the arc is small and that the appearance of oxide film inclusions in the deposited metal despite the poor cleaning effect can be suppressed, so that you get a deep penetration gets into the plates. In view of this, the arc length should be 0.5 to 5 mm.

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In the method according to the invention, the non-melting Electrode consumed little when negative potential is applied to it, so that one Use a high welding current and a deep penetration or penetration into the plates can achieve. If the welding current is below 300 A, there is deep penetration due to insufficient heat supply unavailable. However, if the welding current exceeds 2000 A for vertical and horizontal welding or when welding in an inclined position vertically, the force or energy emanating from the arc becomes too much so that it becomes impossible to prevent the molten metal from dripping down, and accordingly also does not receive any relevant weld seam or deep penetration.

The penetration depth or penetration depth is strongly influenced by the composition of the protective gas. It has been found through numerous experiments that an inert gas containing at least 50% helium is necessary for the satisfactory practice of the invention. If an inert gas containing less than 50% helium is used as the shielding gas, the width of the weld seam or weld bead cannot be large even if the welding current is increased, nor is it possible to achieve a large penetration depth. If a double protective cover is used, at least the protective gas forming the inner protective must meet the above-mentioned condition, while the outer protective gas can have any desired composition. In order to achieve the desired goal, it is desirable that the specific weight of the outer protective gas is greater than that of the inner protective gas.

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In Fig. 6 is an embodiment of the invention shown. According to FIG. 6a, there is a weld groove 3 between two plates 1 and 2 with negative electrode in one pass using a high welding current according to the TIG welding process on both sides of the. Weld groove 3 filler material entered into the weld groove. Because of this TIG welding achieves a deep penetration into the inner section of the plates to be welded, such as Fig. 6b shows. Then filler material 5, for example filler metal, is introduced into the weld groove and covers the surface of the metal 4 deposited in the previous TIG welding and the side walls of panels 1 and 2. The filling material is introduced mechanically. If on the deposited Metal 4 is a crater or a bent section, the filler material 5 is entered so that it fits into the welding groove, which is achieved by using an elastic filler material or a before Introducing preheated filler material into the welding groove. Forms through from the filling material 5 TIG welding a second layer of deposited metal 5 'as shown in Figure 6d. These welding processes are repeated on both sides until a complete weld is achieved. At the In the illustrated embodiment, three welding operations are required on each side in order to achieve this goal to reach.

This procedure is explained in more detail using the following two examples.

example 1

Welding condition

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Plates:

Weld groove shape:

Filling material:

Welding current;

JIS H 4000 (1970) A5083-0 aluminum alloy, 60 mm thick;

Rectangular Η shape, as shown in Fig. 6a, with a root depth of 20 mm and a welding groove width of 10 mm;

JIS H 4000 (1970) A5083-0 aluminum alloy, 10 mm wide, 10 mm thick and 500 mm long, which is driven into the welding ^{groove by hand with a hammer after heating to 300 ° C .;}

6OO A direct current, negative potential on electrode;

Welding voltage:

12 V

Welding speed:

5 cm / min.

Electrode:

Shielding gas:

Tungsten electrode containing Thor, 6.4 mm diameter;

Pure helium, 40 l / min.

After a pass of TIG welding on both Pages is finished under the above welding conditions, TIG welding is done under the above Repeated high welding current conditions twice on both sides with filler material entered. In this way you get a sufficiently deep one

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2503046 example Welding condition ° also showed good results JIS H 4000 (1970) 7N (XL-TE - 17 - Plates: Aluminum alloy, 40 mm and broad penetration bzvi ^r . a sufficient penetration 2 thick; and good mechanical properties of the weld. Rectangular Η shape, as in The side bending test at 180 Welding groove shape: 6a shown, 20 mm root Results. deep and 15 mm wide; JIS H 4000 (9170) A5OO5 Alu Filling material: minium alloy, 10mm thick, 15 mm wide, being on this Aluminum alloy a 0.5mm thick and 15 mm wide layer Plated from pure zinc is and this filler material by hand into the welding groove is drifted without pre-empted to have been heated; 500 A direct current with at the Welding current: Electrode lying negative Potential; -18-

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Welding voltage:

Welding speed t

Pendulum width: Shielding gas:

13 V;

6 cm / min;
5 mm;

Double protective layer, with the gas forming the inner protective layer being pure helium
300 l / min and the gas forming the outer protective layer is pure argon 30 l / min.

After one pass after the TIG welding process under high welding current without filler material under the above welding conditions becomes the filler material entered into the welding groove and by TIG welding treated with high welding current in one pass on each side of the weld.

In this way, a weld with good Penetration and good mechanical properties.

The filler material to be used according to the invention is described below.

The quality can be selected according to the desired mechanical properties of the weld seam. For example, if JIS H 4000 (1970) A5083-0 aluminum alloy plates are to be welded, the same grade or JIS Z 3232 (1970) A5183 can be used as the filler material. In most cases it is desirable that the filler material have the same composition as the

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- Has 19 plates to be welded.

The filler material preferably has one in plan view Rectangular or square shape, but you can also use circular or oval shapes. The strength of the filling material should be around 10 kg / mm. JIS H 4000 (1970) A5083-0 aluminum alloy has a strength of 30 kg / mm at room temperature, so that it is difficult to use this material at To drive room temperature into the welding groove. It is therefore advisable to set this filler material to about 300.degree with the help of a flame or induction heating before it is driven into the welding groove.

Such a filler material can in this way be driven into the weld groove to adapt its shape even if it is rectangular, square, circular, or oval in shape. So that the filling material However, it fits completely into the weld groove, the following examples of the filler material suggested.

Fig. 7 shows a total of seven different shapes in which the filler material can be brought.

According to Figure 7a, the filler material is in the form of a body with downward sloping walls and a V-shaped slot 21a. When this body 21 into a weld groove with parallel side walls is entered, the slit 21a closes, making the insertion of the filler body 21 easy is to be carried out. Even if the weld groove has somewhat rough side walls, intimate contact can occur between the filler material and the walls of the weld groove can be achieved because the one formed from filler material Body 21 has a certain elasticity.

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Fig. 7b shows a body 22 made of filler material, which is substantially rectangular in cross-section and contains two slots on the top and one in the middle on the bottom, for the same reason and for the same purpose as the slot 21a in the body 21 according to FIG. 7a.

According to FIG. 7c, the filling material is in a body 25 brought out of a fibrous filler and a consists of the same surrounding aluminum foil. This body 25 must protect against water or organic material how to protect mineral oil. Since the fibrous material is wrapped in the aluminum foil, can it will contact the sidewalls of the weld nug uniformly, regardless of dimensions or shape the weld groove.

The filler material body 26 shown in FIG. 7d serves the same purpose as the body 25. The body 26 consists of powdery or granular filling material that is wrapped in an aluminum foil.

Fig. 7e shows a body 27 made of filler material, the a solid or compact filler material 27a and a contains fibrous or powdery filler material 27b, both in a common aluminum foil are enveloped. The solid or compact filler material 27a forms a tip standing in cross section Triangle, so that the forces occurring when driving the body27 into a welding groove are uniform the fibrous filler material 27b are transferred. In this embodiment, the filler materials are 27a and 27b combined with each other, but they can also be separated from each other, and one can after the Introducing fibrous filler material into the sweat

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Only the solid or compact in this filling material Drive in filler material 27a.

11 shows a body 28 made of filler material, which consists of two solid bodies 28a and 28b and an interposed powder layer 28c made of granular or fibrous filler material. The solid bodies 28a and 28b are also made of filler material. If this body is inserted into a welding groove, its width can be reduced without difficulty.

If one introduces filler material body 27 or 28 into a welding groove, the driving force can be uniform the powder filler can be transferred so that entering these bodies into the welding groove is easy and good contact between the filler material and the plates to be welded is achieved.

When welding JIS H 4000 (1970) A5083 aluminum alloys, a filler body according to Use Fig. 7g, which consists of a piece 31 of pure Aluminum and a layer plated thereon 32 is made of pure magnesium of high strength. This body is not tough overall, but his should be chemical composition must be about the same as that of the plates to be welded, which is important in order to to obtain a metal deposit in the area of the weld, the properties of which are those of the joint Panels are the same.

In addition to the above suggestion of mechanically entering the filler material into the welding groove, it is proposed that that molten metal is entered as filler material in the welding groove, whereupon a TIG-

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Welding is carried out with a high current. The filler material can be successfully mechanically can only be used if the weld groove is more or less smooth along the entire weld seam, however, in the practice of welding it turns out that the welding groove often has rough and uneven sidewalls having. In this case it is very useful to weld the filler material in the molten state with the help of MIG welding State to be entered.

From Fig. 8a it can be seen that one first enters the Säiweißnut prepared in accordance with FIG. 6b on both Sides molten metal 5 and this then, as Fig. 8b shows, with TIG welding under high Current welds in, so that weld beads 5 'arise. The molten metal 5 was MIG welding introduced in the manner shown in Fig. 8a. The successive MIG welding according to Fig. 8a and the TIG welding carried out with a high welding current according to FIG. 8b is repeated several times until the weld is done. In this way a thoroughly uniform weld seam is achieved, however, MIG welding or other welding can make the same condition or state reach.

The present invention limits the plate thickness to 20 mm and more because if its thickness is less than 20 mm, the plate itself is welded without an insert. According to the present invention, plates Can be welded with thicknesses of 20 to 100 mm - The welding grooves can be I-shape, V-shape, U-shape, H-shape or X-shape, but that of the two opposite side walls of the welding groove included angles must be less than 30 ° because

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at an angle of more than 30 ° the opening of the welding groove becomes too big and a highly effective welding then. "" can no longer be achieved.

The filler material should be entered in a thickness of about 3 msec 20 mm, the maximum width being should be one to three times the diameter of the non-consumable electrode. If that If filler material is entered with a thickness of more than 20 mm, it can be welded by TIG welding with a high welding current not melted evenly and carefully, whereby the welding stability is adversely affected. Is the layer thickness of the added filler material less than 3 mm, an object of the present invention, namely high efficiency welding, cannot can be achieved. When the width of the layer of filler material, and therefore the width of the weld groove exceeds three times the value of the electrode diameter, the filling material by means of the subsequent TIG welding under high welding current is not sufficiently melted over its entire width, while if the filler material layer is narrower than the electrode diameter, the electrode is light can come into contact with the plates to be welded, so that such an arrangement for welding thick plates is not suitable. When to carry out The electrode used for TIG welding is guided in pendulum movements along the welding groove, the previously discussed limits of the width of the layer of filler material are not to be observed.

When performing TIG welding with a high welding current of the metal entered into the welding groove for remelting the same, the pendulum direction should be the non-melting electrode approximately at right angles to the direction of progress of the weld or to the longitudinal

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direction of the weld. Especially with wider welding grooves it is due to the pendulum movements possible in transverse direction to the welding groove, the filler material over the entire width of the welding groove to melt again. If the pendulum speed is too low, the melting occurs non-uniformly, which leads to poor penetration or poor penetration, while if the penetration is too high Pendulum speed the weld seam is poorly executed and weld defects occur in it. Therefore the pendulum speed should be 10 to 100 full pendulum swings per mower. The length of the total pendulum swings should be less than 10 mm, because pendulum swings over 10 mm have micro-cracks, especially when welding aluminum and aluminum alloys, occur and the effectiveness of welding or the quality of the weld is poor.

If the TIG weld, which is carried out with a high welding current, is carried out with more than two non-consumable welds Conducting electrodes, the distance between successive electrodes should be 30 to 200 mm be. If this distance is less than 30 mm, molten metal will drip harab, because that, from the leading one Electrode heated molten metal has not cooled down enough until it is from the following Electrode is reheated while the molten metal is at an electrode gap of more than 200 mm is cooled too much, so that highly effective welding cannot be achieved. in view of should be the length of time between the moment when the leading electrode rush to the particular point Weld happens, and the time the trailing electrode passes the same point, 4 to Seconds.

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If you enter the filler material after MIG welding in a welding groove according to FIG The upper area of the weld groove, as shown in FIG. 9a, shows a relatively good penetration, while the Insufficient material in the lower area of the sawing groove is melted. In this case, how. Fig. 9b shows that carried out with high welding current TIG weld mainly on the lower part of the Concentrated weld groove. This way of working is particularly advantageous when working in a horizontal position Position or in a horizontal position in an inclined direction. In Fig. 9 is that after MIG welding generated weld seam with the item number 5 and the weld seam produced after TIG welding with the item number 5 *.

In the high welding current TIG welding of the present invention, the surface of the molten metal small. Therefore, the invention can be used both vertically and horizontally also use for flat or flat welding. Vertical welding is also possible in an inclined position Direction or horizontal welding in an inclined direction is applicable.

When the TIG welding according to the invention is carried out in practice with a high welding current, the non-consumable Electrode is preferred for vertical welding or vertical welding in an inclined direction led down. The strong arc force emanating from the non-consumable electrode holds the molten metal and prevents the same drips out of the welding zone. Moving the non-consumable electrode is used to Welding condition or welding conditions are stable

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keep. When filling material mechanically in the welding groove is introduced, it is important that the non-consumable electrode moves from top to bottom will. However, if the filler material has been introduced into the weld joint or weld groove by means of MIG welding, the non-consumable Also lead the electrode from the bottom up, because in this case the filler material is already from the MIG-Schwelflbn has been fixed in the weld joint.

MIG welding is preferably done from the bottom up carried out. If you do it from top to bottom, there is a risk that the molten metal due to its gravity and the arc energy or arc force developed during MIG welding drips out of the welding zone. Generally one can say that the welding current in MIG welding is small compared to TIG welding, so it in MIG welding in vertical or inclined vertical

". ,, is difficult,

Direction / molten metal with the help of the arc to hold in the weld joint.

As can be seen from the present explanation, the invention provides a method for welding Created from thick sheets of aluminum and aluminum alloy with a tight weld joint that is quick and effective is to be carried out and produced qualitatively flawless weld seams using known processes for the same purpose cannot be achieved.

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509832/0707

Claims (21)

G 49 757 KOBE STEEL, Ltd., 3-18, 1-Chome, Wakinohama-Cho, Fukiai-Ku, KOBE / JAPAN Patent claims: Process for welding more than 20 mm thick plates made of aluminum or aluminum alloys with a narrow welding joint by means of a non-melting electrode, thereby geke η nzei ch η et that one first / the welding joint a filler material is entered, then direct current of more than 300 A between the non-melting electrode and does not apply a sharp or pointed electrode and the plates to be welded together in such a way that the electrode has negative polarity, the arc length being kept between 0.5 to 5 mm and the welding point being covered with an inert protective gas containing at least 50% helium or protects. 2.) The method according to claim 1, characterized in that the filler material by MIG welding into the Welding joint is entered and that a TIG welding is then carried out. 3.) The method according to claim 1, characterized in that the filler material is mechanically entered into the weld joint, whereupon a TIG weld is carried out. -28- S09832 / 0707 4.) The method according to claim 2, characterized in that that the input of the filler material by means of MIG welding into the weld joint and the subsequent renewed melting of the filler material by means of TIG-Süaweißung to be repeated several times. 5.) The method according to any one of claims 1 to k, characterized in that the TIG welding is carried out under a double protective layer, at least the protective gas forming the inner protective layer consists of at least 50% helium. 6.) Method according to one of claims 1 to 5, characterized in that of the two opposing weld joint walls the included angle to be welded together is less than 30 °. 7.) The method according to any one of claims ti to 6, characterized in that the filler material is entered in a layer thickness of 3 to 20 mm and rather a maximum width of one to three times the diameter of the electrode in the weld joint. 8.) Method according to one of claims 1 to 7, characterized in that the non-melting / de electrode is guided straight along the welding joint. 9.) Method according to one of claims 1 to 7, characterized in that the non-melting electrode is guided over the weld joint in a pendulous manner with the individual deflections of the pendulum movements approximately at right angles to the progressive direction -29- 609832/0707 - 29 welding can be carried out. 10.) Method according to claim 9, characterized in that the pendulum frequency is 10 to 100 pendulum cycles per minute. 11.) The method according to claim 9 or 10, characterized characterized in that the pendulum width or the deflection of the pendulum movements is less than 10 mm. 12.) The method according to any one of claims 1 to 11, characterized in that more than two non-melting Electrodes are used and the distance between the leading and following electrodes is 30 to 200 mm amounts to. 13.) The method according to any one of claims 1 to 12, characterized in that when using more than two non-melting electrodes, which are guided one behind the other over the weld seam Electrodes at a time interval of 4 to 60 seconds. each about a specific point the weld seam. 14.) The method according to any one of claims 1 to 13, characterized in that the points of Weld seam where a good penetration or a good penetration by MIG welding is not possible is to be achieved, can be welded by means of TIG welding, whereby a deep penetration or a deep penetration is achieved in this part of the weld seam. -30- 509832/0707 15.) Method according to one of claims 1 to 14, characterized in that in the vertical direction is welded. 16.) The method according to any one of claims 1 to 15, characterized in that vertically in an inclined Position is welded. 17.) The method according to any one of claims 1 to 16, characterized in that the non-melting Electrodes in the case of vatical welding or vertical welding in an inclined position be guided downwards. 18.) The method according to any one of claims 1 to 16, characterized in that in the case of the vertical Welding or vertical welding in an inclined position, MIG welding from below and the TIG welding is carried out from top to bottom. 19.) The method according to any one of claims 1 to 16, characterized in that the vertical Welding or vertical welding in an inclined position is MIG welding from bottom to top and the subsequent TIG welding is also carried out from bottom to top. 20.) Method according to one of claims 1 to 14, characterized in that in the horizontal
Direction is welded ,, * 21.) Method according to one of claims 1 to 14, characterized in that in the horizontal direction and inclined position is welded. 5 09832/0707