JPH05208295A - Aluminum alloy filler metal for mold and its production - Google Patents

Abstract

PURPOSE:To provide the filler metal which is low in crack sensitivity even in repair welding of an aluminum alloy for molds for plastics, etc., and more particularly Al-Zn-Mg-Cu alloys and exhibits the etching property equiv. to the etching property of a base material in spite of photoetching. CONSTITUTION:This filler metal contains 3 to 8% Zn, 1 to 6% Mg, 0.5 to 3% Cu, 0.2 to 0.9% Mn, 0.05 to 0.5% Cr, 0.05 to 0.2% Ti, 0.01 to 0.2% B and 0.05 to 2% Zr, further, contains 0.02 to 1% Ag at need and consists of the balance Al and unavoidable impurities. Zr of a solid soln. amt. or above is incorporated into the filler metal by remelting the cast ingot of an aluminum alloy consisting of the compsn. cast by an ordinary method by a zone melting method with which a melting width of one time is specified to <=30mm by using an energy beam (electron beam, laser beam, etc., having a high power density of 10<4> to 10<9>w/mm<2> and subjecting the melt to rapid solidification at >=1X10<2> deg.C/sec solidification rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filler material used for welding aluminum alloy molds for molding plastics and the like.

[0002]

2. Description of the Related Art Molds for molding plastic and the like have hitherto been
Most of them were made of steel, but they had drawbacks such as heavy weight, poor workability, and easy rusting. In order to solve these problems, an aluminum alloy has recently been used in a mold.

When an aluminum alloy is used for the mold,
Compared with steel molds, (1) shot cycle is shortened due to good thermal conductivity, which improves productivity, (2)
It has features such as good workability, reduced processing time, (3) light weight of about 1/3, and easy to attach / detach and maintain because it does not rust easily.

[0004]

Repair welding is indispensable for molds due to design changes and processing errors. However, aluminum alloys used in molds, especially 7000 series alloys
(For example, 7 of the highest strength among aluminum alloys
075) has very poor weldability, and welding has generally been avoided. As an exception, Al-Mg based filler metal that is preheated to 200 ° C or higher and has low cracking susceptibility (for example, 5356
However, there are the following problems.

(1) Weld cracking occurs. (2) Since the photo-etching property of the photo-etching is different between the welded part and the base metal part, the bead mark of the welded part is transferred to the product.

Even if an Al-Mg based filler material having a low cracking susceptibility is used, the Al-Zn-Mg-Cu alloy having the highest cracking sensitivity among aluminum alloys is not sufficiently improved.

As a method for improving the cracking susceptibility of Al-Zn-Mg type alloys and the like, for example, "Light Metal" Vol.
No. 11, p.470-480, Zr, Ti
It is effective to add a small amount of B or B, and Zr is the most effective, and the effect becomes more remarkable as the added amount increases. However, the maximum solid solution amount of Zr in the equilibrium state is 0.3%, and it is necessary to add more than the solid solution amount of Zr in order to improve the crack susceptibility of this system alloy to a level at which there is no practical problem. .. However, in the conventional casting method using a die, the cooling rate during solidification is as slow as 10 ² ° C / sec or less, and when Zr in a solid solution amount or more is added, excess Zr forms a huge crystallized substance. as a result,
In order to cause workability deterioration such as rolling and wire drawing, practical addition of Zr was limited to within the solid solution amount range, and there was a limit to improving the weld crack susceptibility of this system alloy.

An aluminum alloy filler metal is proposed in Japanese Patent Laid-Open No. 63-157792, but Zr addition is as small as 0.4% and Al-Zn-which has the highest cracking sensitivity among Al alloys. In order to improve the crack susceptibility of the Mg-Cu alloy to a level at which there is no practical problem, it is insufficient from the viewpoint of improving the crack susceptibility.

Further, when an Al-Mg type filler having low cracking susceptibility is used, a difference in composition between the base material and the welded portion causes a difference in etching property in photoetching, resulting in a bead mark in the welded portion. Is transcribed to.

The alloy of the present system is Z in order to enhance its strength.
Although it contains n, Mg, and Cu, its cracking susceptibility becomes higher due to higher strength, and weld cracking and stress corrosion cracking are likely to occur. Therefore, there are many problems from the viewpoint of crack susceptibility and photoetchability.

The present invention has been made in view of such circumstances, and has low cracking susceptibility even in repair welding of aluminum alloys for molding dies such as plastics, especially Al-Zn-Mg-Cu alloys. It is an object of the present invention to provide a filler material that exhibits the same etching properties as the base material even if it is photoetched.

[0012]

As a result of intensive studies conducted by the present inventor in order to improve the above-mentioned drawbacks of the conventional filler metal, Al-, which has the highest strength among aluminum alloys.
In welding of a Zn-Mg-Cu alloy die, Al-Zn-
Addition of a large amount of Zr to the Mg-Cu composition to improve weld crackability and obtain photoetchability equivalent to that of the base metal. Furthermore, addition of Ag can improve stress corrosion crack resistance. By remelting and rapidly solidifying an ingot produced by a usual method by a high energy beam, it was found that a large amount of Zr above the amount of solid solution can be contained.
The present invention has been made here.

That is, according to the present invention, Zn: 3 to 8%, Mg:
1-6%, Cu: 0.5-3%, Mn: 0.2-0.9%, C
r: 0.05-0.5%, Ti: 0.05-0.2%, B: 0.0
1 to 0.2%, Zr: 0.05 to 2%, Ag: 0.02 to 1% if necessary, and the balance Al and inevitable impurities. The gist is a filler metal for welding an aluminum alloy for a molding die.

Further, the manufacturing method thereof is as follows:
Using an energy beam with a high power density of ⁴ to 10 ⁹ w / mm ² and remelting by the zone melting method with a melting width of 30 mm or less once, solidification rate of 1 × 10 ² ° C / sec or more It is characterized in that it is rapidly solidified by, and contains Zr in a solid solution amount or more.

Next, the present invention will be described in more detail.

[0016]

[Action]

First, the reasons for limiting the chemical components in the filler metal of the present invention will be described.

Zn contributes to strengthening strength, but if it is less than 3%, it does not contribute to strengthening, and if it exceeds 8%, corrosion resistance and weld crack resistance deteriorate. Therefore, the amount of Zn is 3-8
The range is%.

Similar to Zn, Mg contributes to strengthening of strength, but if it is less than 1%, its effect is not exerted, and if it exceeds 6%, corrosion resistance and workability are deteriorated. Therefore, the amount of Mg is 1-6
The range is%.

Cu, like Zn and Mg, also contributes to the strengthening of strength, but if it is less than 0.5%, it has no effect.
%, The weld crackability, workability and corrosion resistance deteriorate. Therefore, the amount of Cu should be in the range of 0.5 to 3%.

Mn contributes to the strengthening of strength and the improvement of corrosion resistance, but if it is less than 0.2%, it has no effect, and if it exceeds 0.9%, the workability deteriorates. Therefore, the amount of Mn is 0.2 to 0.2.
The range is 9%.

Cr contributes to the improvement of the corrosion resistance and the stress corrosion cracking resistance, but if it is less than 0.05%, it is not effective, and if it exceeds 0.5%, the mechanical properties are deteriorated, which is not preferable. Therefore, the Cr content is set to be in the range of 0.05 to 0.5%.

Ti and B contribute to the improvement of the weld cracking property by refining the crystal grains, but if Ti is less than 0.05% and B is less than 0.01%, the effect is not obtained, and each is 0.2. %, It is not preferable because it forms a compound with Al and deteriorates toughness. Therefore, the Ti amount is 0.
05-0.2%, B amount is 0.01-0.2%.

Like Ti and B, Zr contributes to the prevention of weld cracks by refining the crystal grains, but if it is less than 0.05%, it is poor in crack prevention, and conversely if it exceeds 2%, toughness and workability are poor. It is not preferable in terms of deterioration. Therefore, the Zr content is in the range of 0.05 to 2%.

Since Ag has the effect of preventing stress corrosion cracking and increasing strength, it can be added if necessary. When it is added, if it is less than 0.02%, it is not effective, and if it exceeds 1%, it is not preferable because it is inferior in weldability and it is uneconomical.
The range is%.

Next, the manufacturing conditions of the above-mentioned filler will be described.

Of the above-mentioned components, Zr is a vanishing element, so that when it is added to the filler metal, the effect of preventing cracking is reduced compared to when it is added to the base metal. For this reason,
More Z added to the base material to improve crackability
It is necessary to add r amount. However, Zr in equilibrium
The solid solution amount is 0.3% or less, and in the casting method using a normal die, the cooling rate during solidification is as slow as 10 ² ° C / sec or less. Is not preferable because it forms a huge crystallized substance and causes deterioration of workability.

Therefore, as a result of intensive studies on a method of adding a large amount of Zr without forming a huge crystallized product, a very high energy density of 10 ⁴ to 10 ⁹ w / mm ² was obtained. We focused our attention on welding with an energy beam, such as an electron beam or a laser beam.

In the case of this welding, the bead width is very narrow,
A deep penetration bead is formed. However, when a solid solution amount of Zr or more is added, if the power density is 10 ³ w / mm ² or less, a huge crystallized product is formed and workability is deteriorated, so that the power density is 10 ⁴ to It has been found that it needs to be as high as 10 ⁹ w / mm ² .

Therefore, according to this principle, an ingot made by casting an aluminum alloy having a composition containing Zr in a solid solution amount or more with a usual die (cooling rate is slower than 1 × 10 ² ° C / sec) is used. Applied for melting. As a result, in the usual die casting method, a huge crystallized substance is formed when Zr in the solid solution amount or more is added, whereas when it is completely remelted in the thickness direction, Zr in the solid solution amount or more is formed. It has been found that even if added, up to 2%, high Zr addition becomes possible without forming a huge crystallized substance.
For example, by using the welding conditions described below and performing zone melting at a remelt pitch of 30 mm or less at one time, a cooling rate during solidification of the ingot is 1 × 10 ² ° C / sec or more, and as a result, Even if Zr is added in excess of the soluble amount, up to 2% can be added without forming a huge crystallized substance.

The cooling rate is required to be 1 × 10 ² ° C / sec or more, preferably 3 × 10 ² ° C / sec or more. In addition,
Although there is a continuous casting method as a method for rapid solidification, a high cooling rate corresponding to the cooling rate during solidification by the zone melting method cannot be obtained.

In the case of a method in which the heat sources are not continuous but the power density is aggregated (increased) and irradiation is performed periodically, 10 ⁹ w /
Although it is possible to obtain a power density of mm ² or more, in the case of a method of continuously irradiating a heat source like the method of the present invention,
The upper limit of the power density was set to 10 ⁹ w / mm ² because it is not possible with current equipment.

Aluminum alloys having various component systems and compositions can be used as a base material using the present filler metal. 7000 series Al, which has the highest strength among all aluminum alloys
Greatly effective in welding of -Zn-Mg-Cu alloy. Needless to say, the welding method is not particularly limited.

Next, examples of the present invention will be described.

[0035]

【Example】

[Table 1] The ingot obtained by casting a filler material made of an aluminum alloy having the chemical composition shown in Fig. 1 by a normal die method (thickness: 50 mm)
About using an electron beam,

[Table 2] After melting again in the width and length directions of the ingot so that it melts completely in the wall thickness direction under the conditions shown in, a welding rod with a wire diameter of 3.2 mm is manufactured by rolling and drawing and used for the TIG welding test. did. The base material used for TIG welding is Al-Zn-Mg-
It is 7075-T6 which is a Cu-based alloy. In Table 1, No.
1 to No. 7 are the filler metal of the present invention, No. 7 to No. 21 are comparative materials, and No. 22 is the conventional material (5356).

In the TIG welding test, as shown in FIG. 2, a V-shaped groove 3 having a depth of 5 mm and a groove angle of 90 ° is provided in the central portion of the test plate 1 having the shape and dimensions shown in FIG. The groove portion of this base material 2 is formed by the AC / TIG welding method.

[Table 5] The overlay welding was performed under the welding conditions shown in. After that, the welding bead portion 4 was deleted and flat finishing was performed.

The material having the finished surface 5 was tested for the weld cracking property and photoetching property required for a mold for molding plastics and the like. The weld cracking property was evaluated by inspecting the presence or absence of cracks on the surface of the welded portion by the penetrant flaw detection test method, and ◯ when there was no crack, and x when there was a crack. The photo-etching property was determined by dividing the photo-etching into three equal parts as shown in FIG.

The stress corrosion cracking resistance is 3 g / l Na at 100 ° C. when a stress of 15 kgf / mm ² is applied by the three-point support method.
It was immersed in a mixed aqueous solution of Cl, 36 g / l of CrO ₃ and 30 g / l of K ₂ Cr ₂ O ₇ and observed for cracks.
(5356) in comparison, and when it is particularly excellent, ◎,
When excellent, it was evaluated as ◯, when it was equivalent, it was evaluated as Δ, and when it was inferior, it was evaluated in four stages. The workability is determined by the presence or absence of cracks during the rolling process in the welding rod creation process,
The case where the crack length was 10 mm or less was evaluated as ◯, and the case where the crack length was 10 mm or more was evaluated as x.

The above test results

[Table 3] Shown in.

No. 8 of the comparative material has a small amount of Zn and no improvement in photoetching property is observed. No. 9 has a large amount of Zn and is inferior in weld crackability and workability.

The comparative material No. 10 has a small amount of Mg and no improvement in photoetching property is observed. No. 11 has a large amount of Mg and is inferior in workability.

The comparative material No. 12 has a small amount of Cu, and no improvement in photoetching property is observed. No. 13 has a large amount of Cu and no improvement in cracking susceptibility is observed.

No. 14 of the comparative material has a small amount of Mn and no improvement in photoetching property is observed. No. 15 has a large amount of Mn and has deteriorated workability.

The comparative material No. 16 has a small amount of Cr and no improvement in photoetching property is observed. No. 17 has a large amount of Cr and has deteriorated workability.

The comparative material No. 18 has a small amount of Ti and B and is inferior in weld cracking. No. 19 has a large amount of Ti and B, and the workability is deteriorated.

No. 20, which is a comparative material, has a small amount of Zr and no improvement in welding cracks is observed. No. 21 has a large amount of Zr and causes deterioration of workability. Conventional material No. 22 is inferior in crack susceptibility, photoetching property, stress corrosion cracking property and workability.

On the other hand, all the materials of the present invention are excellent in crack sensitivity and photoetching property. In addition, it has excellent workability, and its stress corrosion cracking resistance is equal to or higher than that of conventional materials.

Further, the results of examination on the influence of the ingot making method on the workability in the case of various amounts of Zr are shown.

[Table 4] Shown in. It can be seen that the method of the present invention (remelting method) is superior to the conventional method with less occurrence of edge cracks during rolling.

[0049]

As described in detail above, according to the filler material of the present invention, an aluminum alloy for molding plastics,
In particular, even when repairing and welding a die made of an Al-Zn-Mg-Cu alloy, crack resistance can be improved, and when photoetching is performed, a good surface is obtained in which weld bead marks are not transferred to a molded article such as plastic. .. As described above, the filler material of the present invention has a remarkable industrial effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing the dimensions and shape of a welding test plate material.

FIG. 2 is a side view for explaining the procedure of overlay welding by TIG welding.

FIG. 3 is a perspective view showing a mold material obtained by finishing after welding.

[Explanation of symbols]

 1 Welding test plate 2 Welding base metal 3 V-shaped groove 4 Weld bead 5 Finished weld

Claims (3)

[Claims] 1. By weight% (hereinafter the same), Zn: 3-8%,
Mg: 1-6%, Cu: 0.5-3%, Mn: 0.2-0.9
%, Cr: 0.05 to 0.5%, Ti: 0.05 to 0.2%,
B: 0.01 to 0.2%, Zr: 0.05 to 2%, the balance being Al and inevitable impurities, a filler metal for welding aluminum alloys for forming dies. 2. Zn: 3 to 8%, Mg: 1 to 6%, Cu: 0.0.
5 to 3%, Mn: 0.2 to 0.9%, Cr: 0.05 to 0.5
%, Ti: 0.05 to 0.2%, B: 0.01 to 0.2%, Z
r: 0.05 to 2%, Ag: 0.02 to 1%, and the balance Al and unavoidable impurities, the filler metal for welding aluminum alloys for forming dies .. The method according to claim 3 aluminum alloy ingot of chemical composition according to claim 1 or 2 was cast by usual method, 10 ⁴
Using an energy beam having a high power density of -10 ⁹ w / mm ² and remelting by a zone melting method with a melting width of 30 mm or less at one time, at a solidification rate of 1 × 10 ² ° C / sec or more A method for producing a filler metal for welding an aluminum alloy for a molding die, which comprises rapidly solidifying and containing Zr in a solid solution amount or more.