WO2001085382A1

WO2001085382A1 - Method of manufacturing conductive structure

Info

Publication number: WO2001085382A1
Application number: PCT/JP2001/003851
Authority: WO
Inventors: Hisashi Hori; Shinya Makita; Masaaki Kumai; Shunji Maedomari; Yukirou Ishizu; Rintaro Togashi; Kensaku Fukuda
Original assignee: Nippon Light Metal Company, Ltd.; Akita Zinc Co., Ltd.; Dowa Mining Co., Ltd.
Priority date: 2000-05-08
Filing date: 2001-05-08
Publication date: 2001-11-15
Also published as: JP2002307173A; JP3720240B2; AU2001252695A1

Abstract

With a view to making it unnecessary to employ a filler material lowering the conductivity and keeping satisfactory conductivity, strength and corrosion-resistance after the jointing, an aluminum alloy member of a conductivity of 55 % or more is frictionally agitated and jointed to a material of the same or different kind and assembled into a conductive structure of a desired shape. As the aluminum alloy member of the conductivity of 55 % or more, a 1000-class aluminum alloy is used for a portion requiring no strength, and a precipitation hardened aluminum alloy is used for a portion requiring a strength. When the precipitation hardened aluminum alloy is frictionally agitated and jointed, it is preferable to give the strength by aging after the frictional agitation and jointing. It is also preferable that the temperature in the range of 400 to 300 °C is lowered at a rate of 20 ° /min in the temperature lowering process after the frictional agitation and jointing.

Description

Description Manufacturing method of conductive structure Technical field

The present invention relates to a method for manufacturing a conductive structure such as a bus bar, a cathode for electrolytic deposition of non-ferrous metal, a jig for anodic oxidation, etc. by joining an aluminum alloy without lowering the conductivity. Background art

As a conductive aluminum material, a 100-series aluminum alloy having high conductivity is used, and a 600-series aluminum alloy is used for applications requiring strength. These aluminum alloys are generally joined by TIG welding, MIG welding, or the like using a filler metal.

Using a 1000-series aluminum alloy filler material, a 600-series aluminum alloy is mutually connected, or a 600-series aluminum alloy and a 1000-series aluminum alloy are used. Welding tends to cause weld cracking. Also, TIG,

In fusion welding of MIG, etc., it is inevitable that fine blowholes and sinkholes occur at the joint.

Defects such as weld cracks not only reduce the strength but also cause corrosion to accumulate in cracks and the like in applications exposed to a corrosive environment because electrolytes accumulate in the cracks and the like. Specifically, when mist generated from the electrolytic bath accumulates in cracks and the like when electrolytically refining zinc or the like, corrosion is significantly accelerated. Therefore, for welding this kind of aluminum alloy, 4 0 4 3, 5 3

Aluminum alloys such as 5.6 are used as filler metals, but are currently being updated as corrosion progresses. Since the welded portion has a composition in which the components of the base metal and the filler metal are mixed, the properties become affected by the base metal and the filler metal. In this regard, even if an aluminum alloy such as a 1000 series or a 600 series suitable for applications requiring electrical conductivity is used, even when using aluminum alloys such as TIG welding and MIG welding, the low electrical conductivity of 40 Since an aluminum alloy such as 43 or 53356 is used, a decrease in the conductivity of the weld is inevitable.

The present invention has been devised in order to solve such a problem. By joining aluminum alloys by friction stir welding, it is not necessary to use a filler material that causes a decrease in conductivity. The purpose is to maintain good electrical conductivity, strength and corrosion resistance even after joining. Disclosure of the invention

In order to achieve the object, the present invention is characterized in that a plurality of aluminum alloy members are assembled by friction stir welding into a conductive structure having a required shape.

As the aluminum alloy member, an aluminum alloy having a conductivity of 55% IACS or more when used as a conductive structure is preferable, and a 100-based aluminum alloy is used in a portion where strength is not required. A precipitation-hardened aluminum alloy is used in areas where strength is required. When friction stir welding of a precipitation hardening type aluminum alloy, it is preferable to impart strength by aging treatment after friction stir welding. In addition, during the cooling process after the friction stir welding, it is preferable to cool the temperature range of 400 to 300 ° C at a rate of 20 ° C / min or more. Cathode for metal electrodeposition, jig for non-ferrous metal anodic oxidation, busbar, etc. For example, a cathode for non-ferrous metal electrolytic deposition is a bar made of aluminum alloy of 600 series and a bar made of aluminum alloy of 1000 series. It is assembled by friction stir welding of a plate and a hook made of a 600-series aluminum alloy.

In friction stir welding, as shown in Fig. 1, pin 2 of rotating tool 1 is inserted into the mating surface of member M to be welded, and rotating tool 1 is moved along the butting line while rotating rotating tool 1. The metal M is joined by plastically flowing the metal. Note that the shoulder 3 of the rotary tool 1 is slightly pushed into the member M in order to secure a sufficient amount of metal for joining the member M to be joined.

The welded portion formed by friction stir welding has almost the same properties as the welded member M before welding because there is no mixture of dissimilar materials and the metal of the welded member M is mixed. In addition, since it is a solid-phase diffusion bonding in principle, defects such as blow holes and sink marks do not occur at the bonding portion. Therefore, unlike fusion welding such as TIG welding and MIG welding, the conductivity of the joint does not decrease. The present invention utilizes this advantage to produce a conductive structure by friction stir welding.

The material to be joined M is a material with a conductivity of 55% IACS or higher after tempering to secure current efficiency and prevent heat generation due to Joule heat. , 6101 alloy and the like are used. The 100-based alloy is used for a plate, a busbar, and the like of a cathode for non-ferrous metal electrolytic deposition that does not require much strength. 6 0 6 3 alloy, § Ruminiumu alloys such as 6 1 0 1 alloy, M g ₂ S i, is a material which is strengthened by the precipitation of such C u A l _2, the electrolytic deposition cathode for non-ferrous metal bars Used as hooks, jigs for non-ferrous metal anode oxidation, etc.

In electrowinning, in which metal ions in a sulfuric acid solution are deposited on a cathode using an insoluble anode, aluminum is usually used as a cathode for deposition. For example, in zinc electrowinning, the leachate obtained by leaching the roasted ore with sulfuric acid is used. After purifying and adjusting the solution to be suitable for zinc electrolysis, the resulting zinc-sulfuric acid electrolytic solution was led to an electrolytic cell, and electrolyzed between an aluminum cathode plate and a silver-containing lead anode plate (insoluble anode). Zinc is deposited on the plate surface. When zinc is deposited on the cathode plate to a thickness of about 2 to 3 mm, the cathode plate is pulled up from the electrolytic cell, and the plate-like zinc plate is mechanically peeled off from the cathode plate to collect zinc. The zinc stripped cathode plate is returned to the electrolytic cell again. When the non-ferrous metal electrodeposition cathode of the present invention is used in this method, the conductivity is high, the electric efficiency at the time of zinc electrodeposition is good, the corrosion resistance of the joint is good, and the life of the jig is long. Work loss due to tool maintenance is reduced.

During the friction stir welding, the temperature of the member to be welded M rises, and the alloy component contained in the member to be welded M may form a solid solution in the A1 matrix. The conductivity of the member to be joined M generally decreases due to the solid solution of the alloy component. The lowered conductivity can be recovered by aging treatment to precipitate alloy components after friction stir welding.

In the case of a precipitation hardening type aluminum alloy, if the aging-treated member is friction stir-bonded and then further subjected to aging treatment, overaging occurs and the strength of the member may be reduced. Therefore, a member that satisfies both conductivity and strength can be obtained by friction stir welding the members before the aging treatment and then performing the aging treatment.

If the precipitation hardening type aluminum alloy is gradually cooled during the temperature lowering process after the friction stir welding, alloy components are precipitated as precipitates that are not effective in improving the strength, and the strength is reduced. In such a case, the precipitation hardening type aluminum alloy subjected to friction stir welding is rapidly cooled after friction stir welding to suppress precipitation of alloy components. In particular, it is preferable to cool the temperature range of 400 to 300 ° C at a cooling rate of 20 ° CZ or more. At a cooling rate of less than 20 ° CZ, coarse precipitates are likely to be formed during the cooling process, and the strength can be increased by the subsequent aging treatment. It cannot be improved.

Welded structure is cooled under conditions suppressing the precipitation of the alloying elements, the strength improvement over the effective M g ₂ S i, a source to become an alloy component such as C u A 1 ₂ include in a solid solution state I have. Therefore, the welded structure by aging treatment _{M g 2 S i, C u} A 1 2 , etc. required strength Ri by the and this precipitating is given. Further, since the solid solution alloy component is precipitated by the aging treatment, the conductivity is also improved.

Specifically, by heating the welded structure to 180 to 220 ° C for 1.5 to 10 hours, the strength and conductivity are improved. If both the temperature and the time are below the lower limit, precipitation will be insufficient, and the strength and conductivity will decrease. At a heating temperature of 180 ° C or lower, strength and conductivity may be satisfied by long-term aging, but the cost is high. Conversely, if the heating temperature exceeds 220 ° C or the heating time is longer than 10 hours, the over-aging will occur and the strength will decrease.

As a welded structure assembled by friction stir welding, for example, there is a cathode for non-ferrous metal electrolytic deposition. As shown in FIG. 2, the cathode for non-ferrous metal electrolytic deposition has a cathode plate 4 immersed in an electrolytic solution fixed to a head bar 5 and a hook 6 attached to the head bar 5. The head bar 5 and the hook 6 require strength because the cathode plate 4 is suspended in the electrolytic cell, but the cathode plate 4 does not require much strength.

Therefore, a 1000-base aluminum alloy containing 99.0% by mass or more of A1 was used for the cathode plate 4, and if the A1 content was 97.5% by mass or more, 6003% A 600-series aluminum alloy such as 600 is used for the head bar 5 and the hook 6, and the cathode plate 4 and the hook 6 are friction stir welded to the head bar 5. Since the joint formed by friction stir welding has a composition of a mixture of 1000-series and 600-series metal, good conductivity is maintained, and blow holes into which corrosion promoting substances enter. Gaps such as sink nests are welded It is not formed at all. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory view of a friction stir welding method. FIG. 2 shows a cathode for non-ferrous metal electrolytic deposition provided by the present invention. FIG. 3 is a graph showing that the strength and electrical conductivity of the joint formed by friction stir welding are recovered by the aging treatment. BEST MODE FOR CARRYING OUT THE INVENTION

The JIS A6603 aluminum alloy sheet having a thickness of 15 mm after the solution treatment and before the aging treatment was subjected to TIG welding, MIG welding and friction stir welding, and the effect of the difference in the welding method was investigated.

In TIG welding, 90 ° V-grooves are formed on both the front and back surfaces of the butt joint, and the two front and rear surfaces are subjected to the following conditions: Each surface was welded in three passes. The welding speed at this time was set to SOO mmZ.

In MIG welding, a V groove of 70 degrees was formed on both the front and back surfaces of the butt portion, and welding was performed in two passes on both the front and back surfaces under the conditions of 22 OA-2 OV and 22 OA-2 OV. The welding speed at this time was set to 500 mm / min.

In friction stir welding, a rotating tool with a shoulder diameter of 20 mm, a pin diameter of 8 mm, and a pin length of 7 mm is rotated at 1200 rpm to join aluminum alloy plate materials at a speed of 50 O mmZ. did.

The aluminum alloy sheet material joined by any of the methods was subjected to an aging treatment of heating and holding at 190 ° C. for 3 hours.

Cut out test specimens from each plate and adjust joint strength, conductivity and corrosion resistance I did. The conductivity was measured using an eddy current conductivity meter. The corrosion resistance was evaluated from the corrosion loss when the test specimen was immersed in a 200 g Zl sulfuric acid aqueous solution at 50 ° C for 7 days.

As can be seen from the survey results in Table 1, the joints formed by TIG welding were inferior in strength, conductivity, and corrosion resistance. In the MIG welding using an aluminum alloy as a filler metal, a joint having almost the same conductivity as the base metal was formed, but the strength and the corrosion resistance were poor. In addition, in MIG welding using an aluminum alloy such as 535, 4403 as a filler metal, the electrical conductivity was significantly reduced, and the strength and corrosion resistance were poor. In contrast, the joint formed by friction stir welding was excellent in strength, electrical conductivity, and corrosion resistance. This is considered to be due to the absence of defects such as weld cracks, blowholes and sink marks at the joint. Table 1: Effect of welding method on joints

As the member to be joined M, a 6101 aluminum alloy extruded plate material (thickness: 15 mm, plate width: 70 mm, length: 500 mm) was used. This member to be joined M is an unaged material that has been die-hardened after extrusion.

The end faces in the width direction of the two extruded plates are joined together, and the joint surfaces are friction stir welded Was. The friction stir welding conditions were as follows: using a rotating tool 1 with a shoulder diameter of 2 O mm and a pin 2 with a diameter of 8 mm and a length of 7 mm, a rotation speed of 1200 rpm and a movement speed of 50 O mmZ. Rotation tool 1 was moved along the joint line in minutes. When the temperature of the joint was measured during the friction stir welding, it was found that the temperature reached the maximum temperature of 5300C.

After the friction stir welding, the joined portion was cooled at a cooling rate of 30 in a temperature range of 400 to 200 ° C. at a cooling rate of 30 / min. After cooling, the strength and conductivity of the joint were measured. As a result, the strength showed a low value of ΙΔδΝΖπιπι ^{2 and a} conductivity of 53% IACS. In addition, when the metal structure of the joined portion was observed as it was, the precipitate was clearly reduced as compared with the base metal portion.

Therefore, the extruded plate material subjected to friction stir welding was subjected to aging treatment at 180 ° C to recover strength and electrical conductivity. As shown in Fig. 3, the strength and conductivity increased with the aging treatment time, and after aging treatment for about 4 hours, the values were almost the same as those of the base metal part. However, with long-term aging of more than 8 hours, although the conductivity increased, there was a tendency for the strength to decrease due to overaging.

2 types of cathodes assembled by friction stir welding and MIG welding of 6101 alloy hook 6 and bar 5 and 1700 alloy cathode plate 4 respectively Prepared.

Two cathode plates zinc concentration 5 5 g 1, the sulfuric acid concentration 1 8 5 g Z 1, it was immersed in the treatment liquid of the bath temperature 4 2 ° C, negative pole by energizing 2 4 hours 6 0 OA Zm ² Zinc was electrolytically deposited on the plate.

Table 2 shows the cell voltage, the amount of zinc deposited, and the unit power (the amount of power required to deposit 1 ton of zinc) when each cathode was used. As is evident from Table 2, when the cathode assembled by friction stir welding was used, Unit power consumption was reduced by 1 KWHZ ton compared to the cathode assembled in close contact. Table 2: Effect of cathode assembly method on electrolysis conditions

Industrial applicability

As described above, the present invention utilizes the advantages of friction stir welding in which dissimilar materials are not mixed into the joining portion, and joins the conductive aluminum alloy member without lowering the conductivity. In addition, a welded part that is free from defects such as weld cracks, blowholes, sink marks, etc. as seen in TIG welding and MIG welding is formed, so that a welded structure with excellent strength and corrosion resistance is obtained, and good electrical conductivity is obtained. Used as a bus bar, a cathode for non-ferrous metal electrolytic deposition, a jig for non-ferrous metal anodic oxidation, etc., which require a high rate.

Claims

The scope of the claims

1. A method for manufacturing a conductive structure, wherein a plurality of aluminum alloy members are assembled into a required shape by friction stir welding.

2. A method for manufacturing a conductive structure, comprising: assembling an aluminum alloy member having a conductivity of 55% I ACS or more with a different material or a similar material into a required shape by friction stir welding.

3. Conductivity for use according to claim 2, wherein a precipitation hardening type aluminum alloy is used as an aluminum alloy member having an electrical conductivity of 55% IACS or more, and aging treatment is performed after friction stir welding. The method of manufacturing the structure.

4. After precipitation hardening type aluminum alloy members are friction stir welded,

4. The method for producing a conductive structure according to claim 3, wherein the temperature range of 300 ° C. is cooled at a rate of 20 ° C./min or more.

5. A cathode for non-ferrous metal electrolytic deposition produced by the method according to any one of claims 1 to 4.

Electromagnetic analysis of non-ferrous metals in which a 600-series aluminum alloy bar and a 1000-series aluminum alloy plate and a 600-series aluminum alloy alloy hook are friction stir welded to a 600-series aluminum alloy bar Outgoing cathode.

7. A zinc electrolysis method using the cathode for non-ferrous metal electrolytic deposition according to claim 5 or 6.