JPS58959B2 - Welding rod for inert gas arc welding for aluminum alloys - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in welding rods used for welding aluminum alloy (hereinafter referred to as A1 alloy) castings.

More specifically, it is a welding rod for inert gas arc welding of A1 alloy castings, etc., with a melting point of 500 to 570°C and a Si7 to
12%, Cu 3.5-7%, Mg 0.1-0.5%,
It is configured to contain less than 0.5% Fe and less than 5% ZHo, and can obtain the necessary hardness without solution treatment, and also prevents heat effects on die-cast parts, parts during processing, and completed processing. The present invention relates to a welding rod for inert gas arc welding of A1 alloy castings, which prevents damage and further improves welding workability.

Welding of A1 alloy cast members must basically be avoided since it involves a decrease in the uniformity of the cast member.

However, in a small number of prototype parts, repair welding is performed for the purpose of remediating parts where defects cannot be prevented due to casting design or defects that occur during processing.

The current welding rod for the above-mentioned welding of A7-8i series A1 alloy castings has Si close to eutectic and a small amount of Cu added.

Other At-based welding rods with only 4 to 6% Si added are used.

The parts welded using these welding rods are sufficient if the purpose is to prevent oil leakage, for example, but if strength is required for the function of the part, the parts welded can be melted after welding. It is necessary to carry out conversion treatment.

For this reason, it is currently not possible to perform repair welding on products that require strength during processing or on finished products.

On the other hand, the die-cast A1 alloy has considerably high strength in the die-cast state due to the quenching effect during the die-casting process.

This die-cast member is also subjected to various types of welding in the same way as the cast member.

However, good welding cannot be expected in die-cast members because the blowholes contained therein expand and blow out due to the heating that accompanies welding.

In addition, heat treatment to increase the strength after welding causes blistering, and is practically impossible.

As mentioned above, the conventionally used welding rods for A7 alloy castings are only capable of welding A1 alloy, and cannot be expected to maintain welding workability or strength.

However, as mentioned above, repair welding of A1 polymerized members is currently being carried out, and the need for this is extremely high, so there is a strong desire for a welding rod that can replace the conventional welding rods mentioned above.

The present inventors have devised the present invention in order to effectively solve the above-mentioned problems with conventional welding rods, such as the inability to maintain strength and unfavorable welding workability. be.

The purpose of the present invention is to apply it to A7 alloy castings and A1 alloy die-cast members, and to obtain reliable welding.
Welding for inert gas welding of A1 alloy, which is preferable for maintaining strength because the obtained welded part can obtain the required hardness as it is without solution treatment, and is suitable for welding parts that require strength for component function. Provide a stick.

In addition, the object of the present invention is to have a low melting point, so that even when repairing Al die-cast members, mid-processing parts, finished processing parts, etc., the heat influence on these parts can be prevented as much as possible, and the parts concerned can be To provide a welding rod for inert gas welding of A1 alloy, which achieves the above-mentioned properties without causing any damage, enables smooth and reliable welding, and has excellent welding workability.

Preferred embodiments of the invention will now be described in detail.

The gist of the present invention is that S at a melting point of 500 to 570°C
i 7-12%, Cu3.5-7%, Mg0.1-0
．． Regarding the Al welding rod for inert gas arc welding, such as for A1 alloy castings, containing 5% FeO, 5% or less, and ZnO, 5% or less, the limitations on the temperature and component ratio will be described later.

By the way, the present invention has the following advantages: as mentioned above, the hardness can be obtained without solution treatment, and the melting point is low from the viewpoint of preventing as much as possible the influence of heat on die-cast members, parts during processing, completed processing, etc. The aim is to improve welding workability.

These were secured 72 hours after welding, and by using a welding rod with a low melting point, it was possible to determine the welding range during processing, even on completed parts and die-cast parts.

Next, I will explain how the above was made possible.
It is generally known that various intermetallic compounds are precipitated by adding Sl, Cu, Mg, etc. to Al, and that these compounds undergo an aging precipitation hardening phenomenon over time at room temperature or by constant heating. .

However, the room-temperature age hardening after ASCast is minimal without solution treatment, and even if CusMg is added, we cannot expect much of the room-temperature effect after ASCast when it is captured in A7 alloy castings. Can not.

This is because the solution hardening mechanism greatly influences the degree of aging of the aging effect compound.

In the process of welding AA alloy castings and A1 alloy die-cast members, the inventors performed repair welding using various welding rods to which a limited amount of Cu%Mg was added.

After welding, by leaving it at room temperature, we were able to obtain an increase in hardness as shown in the graph of FIG.

In the graph of Figure 1, the vertical axis represents the hardness (HRB), and the horizontal axis represents the components as shown below. The component proportions are as follows.

In the figure, the symbol × indicated by the line A indicates that the product has been subjected to JIST6 heat treatment after welding, and the symbol ○ indicated by the heddled line indicates the product that has been subjected to JIST6 heat treatment after welding.
00 hour natural aging, and the line C indicates natural aging for 72 hours after welding.

As is clear from this, by leaving it for 72 hours after welding, an increase in hardness corresponding to the solution aging treatment T6 can be obtained.

As is clear from the graph, Si9.5%, Cu4.
The 0% component was identified and the Mg blending ratio was increased from 0.01%. At 0.1% Mg, the hardness required for practical use was obtained under each condition, and as the Mg increased, the hardness increased. There is a tendency.

This is because the part where repair welding is performed by alternating current argon arc welding using a welding rod with such limited addition of Cu%Mg components solidifies in a short time of less than 1 second, and the welded part is made of A7 alloy. This is because the effect was similar to that of the solution treatment mechanism applied to cast iron products.

This is clear from the fact that, as shown in the graph of FIG. 2, no increase in hardness was observed even after heat treatment equivalent to JIST4.

Similarly to the above, the vertical axis in the figure shows the hardness (HRB), the horizontal axis shows the hardness according to the composition a-f, and the line 2 shows the hardness (HRB) after welding, The 0 indicated by the line ho is the same as above.

As shown in the figure, it shows the one that was naturally aged for 200 hours after welding.

From these results, it was found that the aging effect, which cannot normally be expected during the welding process, can be significantly improved by adding small amounts of Cu and Mg during welding.

Therefore, conventionally, strength recovery after welding repair of A1 alloy castings could not be expected without heat treatment, but for the reasons stated above, we have made it possible to reuse A1 alloy products by welding repair, where heat treatment is impossible or extremely difficult. .

Therefore, as mentioned above, the present invention is a welding rod for inert gas arc welding of A1 alloy castings etc., which has a melting point of 500 to 500.
Si7-12%, Cu3.5-7%, Mg0 at 570℃
．． The gist of the composition is to contain 1 to 0.5%, 0.5% or less of Fe, and 0.5% or less of Zn, and the reason for this will be described below.

The reason why the liquidus point of the welding rod is set to 570℃ or less is to prevent the thermal effect on the welded product as much as possible.
By setting the temperature to 70°C or less, there is no need to preheat even large parts, and in the finished product, welding at a low temperature reduces distortion due to heat effects and prevents a decrease in the hardness of the parts, making welding work easier.

Furthermore, in repair welding of die-cast parts, the occurrence of blisters and the like can be suppressed by lowering the welding temperature, and the quality can be improved by making it easier to perform welding, which was previously difficult.

As a result of the above, the welding current could be suppressed to about 20% lower than that of the conventional method, and overall weldability was improved.

The compatibility of the welding rod with the welding base material was excellent, and the welding rod exhibited good properties not found in conventional welding rods.

The components of the welding rod were as described above for the following reasons.

In other words, the composition of the welding rod is from JISAC2B to JISADC
In order to make it possible to use up to 12 species as a base material, Si has a eutectic point of 7 to 7.
It was set at 12%.

Also, the optimum range for Cu is from 3.5 to 3.5 from the relationship between melting point and hardness.
It was set at 7%.

And when Mg exceeds 0.5%, the toughness deteriorates significantly.
As mentioned above, if it is <0.1% or less, the hardness will decrease significantly,
Conventionally, 0.1%~ which is an active ingredient in terms of increasing hardness.
It was set to 0.5%.

In addition, when containing Fe and Zn, the content rate of Cn is 3
．． This is to prevent the disadvantages caused by setting the Fe content to 5% to 7%, that is, the disadvantage of loss of toughness, and to suppress precipitation aging of Cu. In this case, Fe suppresses the precipitation of acicular intermetallic compounds with Si. Therefore, the upper limit is set at 0.5%, and since Zn is preferentially oxidized during melting during welding and remains as an oxide in the welded part, it is suppressed to 0.5% or less.

In addition, the rest of the welding rod is 9mm, similar to the general AA alloy welding rod.
Almost 0% by weight of Al and small amounts of Mn and Cr.

It consists of Ti, etc.

For example, in JIS symbols, A1070-BY, A110
0-BY.

A3154-BY etc.

Next, examples of the present invention will be described.

Example 1 A crankcase for a motorcycle was obtained by die-casting made of a JISA DCI type 2 alloy, and the holes in the defective parts due to poor machining were welded with AC argon using an A7 alloy welding rod containing 5i 11.5%, Cu 6.0%, and Mg 0.15%. Gas arc welding (TIG)
), and after welding repair and leaving it at room temperature for 80 hours, welded part hardness was HRB55.

The hardness of the die-casting base material is in the range of HRB 50 to 55.

Example 2 A cylinder head for a four-wheeled vehicle was machined by milling the seat surface for tightening a stud bolt made of JISAC2 metal. Blow-shaped cavities were observed.

In order to stabilize the bolt tightening force, 7% Si is added to that part.
AC argon gas arc welding (TIG) was performed using an A/ alloy welding rod containing 4% Cu, 0.3% Mg, and the hardness of the weld reached HRB58 when left at room temperature for 72 hours after welding repair.

In addition, the hardness regulation for this cylinder head is HRB55 to 65.
This prevented fluctuations in bolt tightening axial force.

As is clear from the above, according to the present invention, since the liquidus point of the welding rod is 570°C or less and the above-mentioned components are used, welding can be performed at a low melting point, and the thermal influence on A1 alloy castings and A1 alloy die-cast members can be minimized. It is possible to weld A1 alloy with little distortion while suppressing the amount of strain caused by the welding, and also to prevent a decrease in hardness.

Moreover, by adopting the above-mentioned component ratio, it has excellent compatibility with the base metal, and the hardness of the welded part can be maintained sufficiently for practical purposes. It can be performed reliably while maintaining the required strength, and the hardness can be increased without going through solution treatment, which was impossible to expect with conventional welding rods for A7 alloy.
In particular, members such as Al die-cast members for which solution treatment is impossible or extremely difficult can be welded while maintaining the required hardness and suppressing the occurrence of blisters.

Furthermore, as mentioned above, it can be welded at a low melting point, which makes welding work easier, improves workability, expands the range of welding objects, and also contributes to reducing power consumption, making it economical. demonstrate.

[Brief explanation of drawings]

1 and 2 are graphs for explaining the present invention.

Claims (1)

[Claims] 1% by weight Si7-12%, Cu3.5-7%, Mg
Contains 0.1 to 0.5%, 0.5% or less of Fe, and 0.5% or less of Zn, and the remainder is substantially Al, and furthermore, the melting point is in the range of 500 to 570°C, eliminating the need for solution treatment. Welding rod for inert gas arc welding of aluminum alloys.