JPH1034377A - Manufacture of joined member between aluminum based material and iron based material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a joined member not generating an intermetallic compound in the interface between an aluminum layer and iron material and not generating a peeling in the brazed part by heating even in the case of using as cooking vessels. SOLUTION: The iron material 21, previously provided the aluminum layer 22 improving the wettability of a brazing filler metal on a joining surface, is brazed to an aluminum material 1 at the temperature range of >=490 deg.C to <550 deg.C. A brazing filler metal 3 composed of, by weight, 20-60% Zn, 3-6% Si and the balance Al with impurities is used for brazing. A flux is composed of KCl-NaCl-BaCl2 flux consisting of, by wt., 23.0-27.0% KCl, 15.0-19.0% NaCl, 49.0-53.0% BaCl2 , and additives consisting of, by wt., 0.5-5% LiF and 1-10% ZnCl2 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining member in which an aluminum material and an iron-based material are joined by brazing, for example, an aluminum material which can be applied to electromagnetic cooking utensils such as pots, frying pans, rice cookers and the like heated by electromagnetic induction. The present invention relates to a method for manufacturing a joining member between a material and an iron-based material.

[0002] In this specification, the term aluminum is used to include its alloys.

[0003]

2. Description of the Related Art Generally, cooking utensils are required to be lightweight, easy to handle, and resistant to rust. Further, in addition to the above-mentioned required characteristics, it is necessary for an electromagnetic cooking appliance used in an electromagnetic cooking appliance, which has recently become popular, to generate heat by electromagnetic induction. Therefore, the vessel body is made of lightweight and rust-proof aluminum, and the vessel for electromagnetic cooking is formed by a joining member in which a highly permeable iron-based material is joined only to a portion heated by electromagnetic induction.

[0004] One of the simplest methods of joining an iron-based material to a part of the aluminum material as described above is joining by brazing. However, iron-based materials generally have poor wettability of the brazing material. A method has been adopted in which an aluminum layer having good wettability of a brazing material is clad in advance on one side of an iron-based material by rolling, and the aluminum material and the iron-based material are brazed and joined via the aluminum layer.

[0005]

However, when the joining member joined by the above method is applied to an electromagnetic cooking utensil or the like, if the cooking utensil is repeatedly heated and cooled, it is clad by rolling. There has been a problem that the iron-based material and the aluminum layer are separated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. Even if the heating and cooling are repeated, the joining member, in particular, the aluminum layer and the iron-based material are not separated from each other. An object of the present invention is to provide a method of manufacturing a joining member between a material and an iron-based material.

[0007]

As a result of intensive studies and efforts, the present inventors have found that the cause of the separation is a fragile intermetallic compound generated at the interface between the iron-based material and the aluminum layer. Furthermore, it has been found that the intermetallic compound grows on the interface by heating during brazing.

Further, as a result of repeated experiments by the present inventors, it has been found that brazing bonding can be performed at a temperature at which the intermetallic compound does not grow, and that heat resistance, which is a characteristic required for cooking utensils, is satisfied. The inventors have found possible brazing materials and fluxes indispensable for brazing, and have completed the present invention.

That is, according to the method for manufacturing a joining member of an aluminum material and an iron-based material according to the present invention, the iron-based material is provided with an aluminum layer on its joining surface in advance, and the brazing material is
A brazing filler metal containing 20 to 60 wt% of Zn and 3 to 6 wt% of Si and the balance of aluminum and impurities is used. The flux is 23.0 to 27.0 wt% of KCl and NaC.
_{l: 15.0~19.0wt%, BaCl 2:} 49.0~
One or both of LiF in an amount of 0.5 to 5% by weight and ZnCl _{2 in} an amount of 1 to 10% by weight are added to a KCl—NaCl—BaCl ₂ flux having a composition of 53.0% by weight. The gist is that the iron-based material is brazed to an aluminum material through an aluminum layer using the flux thus obtained.

[0010] In the method of manufacturing a joining member by brazing using the above brazing material and flux, brazing can be performed at a relatively low temperature of less than 550 ° C. Therefore,
As in the prior art, due to the high brazing temperature, peeling at the interface due to the brittle intermetallic compound growing at the interface between the iron-based material and the aluminum layer does not occur. In addition, during normal heating of cooking utensils, etc., the brazed part does not melt and the joint does not peel off, satisfying the required heat resistance as a cooking utensil, and stably joining. A member can be used.

Furthermore, if at least the peripheral portion of the joint surface of the joint member manufactured by the above method is subjected to friction welding, the peripheral portion of the joint surface which is most likely to be peeled is melt-joined, so that heating and cooling are repeatedly performed over a long period of time. Even in the case of peeling, peeling can be effectively prevented. Furthermore, since the joining surface peripheral edge is joined in a manner to seal the brazed portion, even if the joining member is abnormally heated, the brazing material does not melt,
Further, it is possible to prevent rusting of the brazing material and maintain a good appearance.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment according to the present invention will be described with reference to the accompanying drawings in connection with the manufacture of electromagnetic cooking utensils.

FIG. 1 shows an electromagnetic cooking utensil, wherein (1) is an aluminum material formed into an utensil shape to form a utensil main body, and (2) is the above-mentioned utensil main body (1).
Is a heat-generating member composed of an iron-based material (21) and an aluminum layer (22) joined to the outer surface of the bottom portion.

As the aluminum forming the vessel main body (1), it is preferable to use a 1000 series or 3000 series aluminum material having good workability in order to form a vessel shape by deep drawing or the like.

The heating member (2) is made of an iron-based material (21).
Is a member provided with an aluminum layer (22) for improving the wettability of a brazing material (3) to be described later on the surface thereof.

As the iron-based material (21), any iron-based material can be selected depending on its use. In the case of this embodiment, since it is used as a heating element of an electromagnetic cooking utensil, a material capable of induction heating, for example, soft iron such as ferrite SUS such as SUS400 or SS400 may be used.

The aluminum layer (22) is provided on the surface of the iron-based material (21) to improve the wettability of the surface of the iron-based material (21). Therefore, aluminum having good wettability to the brazing material (3) described later is selected.

The means for providing the aluminum layer (22) on the surface of the iron-based material (21) is not particularly limited.
The method of hot-dip plating aluminum can be mentioned in 1). The thickness of the aluminum layer (22) is preferably set to 10 μm or more in order to efficiently secure good wettability of the brazing material.

The brazing material (3) to be joined must be melted at a temperature at which no intermetallic compound is generated at the interface between the iron-based material (21) and the aluminum layer (22), specifically, at a temperature of less than 550 ° C. On the other hand, on the other hand, it is necessary not to melt at a temperature by heating in actual use such as heating as a cooking utensil.
More specifically, it is a brazing material made of aluminum containing Zn and Si, and if the Zn content is less than 20% by weight, 55%.
If the content does not melt at a temperature lower than 0 ° C. and the content exceeds 60 wt%, the brazing material may be melted at a temperature caused by heating such as cooking. In addition, the content of Si is less than 3 wt% or 6 wt%.
In all cases, the brazing filler metal becomes brittle and is not suitable for joining. Therefore, Zn: 20-60 wt%, S
i: It is necessary to use a brazing material containing 3 to 6% by weight, with the balance being aluminum and impurities. Particularly preferable contents of the contents of Zn and Si in the brazing filler metal have a lower limit of Zn:
30 wt%, Si: 3 wt%, the upper limit is Zn: 50 wt
%, Si: 5 wt%.

For the brazing, a flux (not shown) is used in order to suppress the oxidation of each part, and this flux must be able to exhibit a flux function at a brazing temperature of less than 550 ° C. is there. Specifically, LiF
Alternatively, a low-temperature brazing flux containing one or two kinds of ZnCl ₂ and the balance being a KCl—NaCl—BaCl ₂ flux is used.

In the low-temperature brazing flux, K
To based Cl-NaCl-BaCl ₂ Flux is because the KCl-NaCl-BaCl ₂ Flux is relatively hygroscopic has a characteristic that low. As such a KCl-NaCl-BaCl ₂ flux, KCl: 23.0 to 27.0 wt%, NaC
_{l: 15.0~19.0wt%, BaCl 2:} 49.0~
The one having a composition of 53.0 wt% is used. Also, a small amount of a fluoride-based flux such as KAlF ₄ , MgF ₂ , CaF ₂ or a eutectic composition of KF + AlF ₃ may be added with these as main components.

LiF and ZnCl ₂ are added for the purpose of lowering the melting point of the low-temperature brazing flux and improving the activity as a flux. However, when the LiF content is less than 0.5% by weight, the effect of lowering the melting point and improving the activity is not recognized. On the other hand, when the content exceeds 5% by weight, the melting point rises, and in any case, the brazing temperature below 550 ° C. Not applicable. Therefore, the LiF content needs to be in the range of 0.5 to 5 wt%, particularly preferably 1.0 to 3.0 wt%. When the content of ZnCl ₂ is less than 1 wt%, the effect of lowering the melting point and improving the activity is not recognized. On the other hand, when the content exceeds 10 wt%, the hygroscopicity as a flux becomes high and the handling becomes troublesome.
Damage to the iron-based material (21) and the furnace body increases. Therefore, the ZnCl ₂ content needs to be in the range of 1 to 10% by weight, particularly preferably 3.0 to 7.0% by weight.

Next, a method of brazing and joining the heat generating member (2) to the vessel body (1) using the brazing material (3) and the flux will be described.

First, as shown in FIG. 2, an object main body (1)
The brazing material (3) is placed on the outer bottom surface, and the aluminum layer (22) is placed thereon.
The heat-generating member (2) is overlapped so that is below.

Here, when the above members are superimposed, the flux is dispersed in water so as to have a concentration of, for example, about 60% to form a suspension, and the suspension is applied to the vessel body using a brush or the like. Apply flux to the outer bottom surface of (1),
After the brazing material (3) is placed, a flux is further applied to the surface of the brazing material (3) so that the flux function is effectively exerted at the time of brazing. The method for applying the flux is not limited to the above method, and the flux may be applied by any method.

Then, in the stacked state, it is placed in a heating furnace for brazing and brazing is performed at a predetermined temperature. If the brazing temperature is lower than 490 ° C., the brazing material (3) does not melt and thus cannot be brazed, while if it is 550 ° C. or higher, the iron-based material (21) and the aluminum layer ( 2
An intermetallic compound grows at the interface with 2). Therefore,
The optimal range of the brazing temperature is 490-550 ° C.

Through the above steps, an electromagnetic cooking utensil in which the heating member (2) composed of the iron-based material (21) and the aluminum layer (22) is joined to the outer bottom surface of the vessel main body (1) composed of the aluminum material. .

More preferably, friction welding is performed on the peripheral edge of the joining surface of the electromagnetic cooking utensil after the brazing. In this friction welding, as shown in FIG. 3, the end of a shaft (4) rotating at a high speed is brought into contact with one of the joining surfaces and pressed toward the other, so that the shaft (4) is joined to the joining member. The aluminum of the vessel body (1) and the aluminum layer (22) of the heat generating member (2) are brought into a molten state by frictional heat caused by the friction with the aluminum, and the aluminum in the molten state is joined together by a pressure applied simultaneously. is there. By performing this friction welding continuously along the periphery of the joint surface,
The periphery of the joining surface can be joined in such a manner that the brazed portion is sealed. Therefore, even when heating and cooling are repeatedly performed for a long period of time, peeling of the container body (1) and the heat generating member (2) can be effectively prevented. Further, it is possible to prevent rust of the brazing material, maintain a good appearance, and prevent the brazing material from flowing out due to abnormal heating.

[0029]

Next, an embodiment of the present invention will be described.

As an aluminum material, a disk made of aluminum (A1100) having a thickness of 3 mm and a diameter of 150 mm was prepared.

SUS430 was prepared as an iron-based material to be joined to the aluminum material, and aluminum (A1) was used as an aluminum layer in order to improve the wettability of the joining surface.
100) was joined to one surface of an iron-based material by rolling. The thickness of each layer of the cladding material is 0.5 mm,
After joining by rolling, a product processed into a disk having a diameter of 100 mm was prepared.

As another iron-based material, soft iron S
Aluminum (A110) for improving the wettability is formed on a disc obtained by processing S400 to a thickness of 0.7 mm and a diameter of 100 mm.
An aluminized steel sheet prepared by hot-dip coating of 0) was also prepared.
The aluminum layer formed by this plating was provided on both surfaces of the iron-based material with a thickness of 0.05 mm.

The brazing material is Zn: 40 wt%, Si: 5 wt%
%, A low-temperature brazing material consisting of the balance aluminum and impurities was used.

As the flux, an aqueous solution in which the following three types were suspended in water at 60% was used. : KCl-NaCl-Ba
7 wt% of LiF and ZnCl _{2 in a} Cl ₂ flux
, KCl-NaCl-BaC
that the LiF added 5wt% to l _2-based flux,:
KCl-NaCl-BaCl ₂ flux to ZnCl
₂ added 3 wt%.

The above members were joined in the following procedure to produce a sample.

A flux is applied to one surface of the aluminum material, a brazing material is placed thereon, and after the flux is applied, a clad material of an iron-based material and an aluminum layer is brought into contact with the aluminum layer and the brazing material. And place 5
Sample 1 was formed by brazing at a temperature of 30 ° C.

Samples 2 and 3 were obtained by changing the flux to flux and bonding the same as sample 1 except for the other.

As the iron-based material, the clad material was changed to the aluminized steel sheet, and the other components were treated in the same manner as the above-mentioned sample 1 to obtain sample 4.

As a comparative example, an iron-based material composed of the aluminum material and the clad material was heated to 570 ° C. using a normal brazing material (Al-9 wt% Si) and a fluoride-based flux containing KAlF ₄ as a main component. The sample was brazed at the above temperature to obtain Sample 5.

Next, the sample joined in the above process was cut, and the interface between the iron-based material and the aluminum layer was observed. Table 1 shows the results.

[0041]

[Table 1]

As can be seen from Table 1 above, no growth of the intermetallic compound was observed in Examples in which brazing was performed at a low temperature. On the other hand, in the comparative example, an intermetallic compound was observed, and many minute cracks caused by the intermetallic compound were observed at the interface between the iron-based material and the aluminum layer.

[0043]

According to the present invention, an iron-based material is brazed to a part of an aluminum material at a relatively low temperature with an aluminum layer interposed therebetween at a relatively low temperature in the presence of an optimum brazing material and flux. is there. Therefore, a brittle intermetallic compound does not grow between the iron-based material and the aluminum layer, and peeling caused by the intermetallic compound can be effectively prevented. Further, even when the joining member obtained by the above-described manufacturing method is exposed to heating by cooking or the like, peeling due to melting of the brazing material does not occur.

Furthermore, if the peripheral edges of the joining surfaces are joined by friction welding, the peripheral edges of the joining surfaces that are most likely to peel are firmly joined, and even if heating and cooling are repeated for many years, the peeling is effectively prevented. be able to. In addition, since the brazing portion is in a sealed state, the brazing material does not melt even by abnormal heating, and also prevents rusting of the brazing material, maintains a good appearance, and stably uses the joining member. can do.

[Brief description of the drawings]

1A is a schematic cross-sectional view of an electromagnetic cooking utensil as an example of an object to which the present invention is applied, (B) is a bottom view, and (C) is an enlarged cross-sectional view of a peripheral edge of a joining surface. It is.

FIG. 2 is a sectional view showing a preparation stage before heating for brazing.

FIG. 3 is a sectional perspective view showing a state where friction welding is performed.

[Explanation of symbols]

 1: Aluminum material (main body) 21: Iron-based material 22: Aluminum layer

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location B23K 20/12 B23K 20/12 G 35/363 35/363 G // B23K 103: 20 (72) Inventor Tanaka Katsuyuki, 224 Kaiyama-cho, Sakai City Showa Aluminum Co., Ltd.

Claims (2)

[Claims] 1. An iron material (21) provided with an aluminum material (1) and an aluminum layer (22) on a joint surface in advance.
When brazing, the brazing material (3) includes Zn: 20 to 60 wt%, Si:
A material containing 3 to 6 wt% and the balance consisting of aluminum and impurities is used. The flux is KCl: 23.0 to 27.0 wt%.
%, NaCl: 15.0 to 19.0% by weight, BaCl ₂ :
KCl-NaCl-B having a composition of 49.0-53.0 wt%
ZnCl the amount of LiF and 110 wt.% of the range of the addition amount of the range of NaCl ₂ Flux of 0.5 to 5 wt%
_An aluminum material, characterized in that the aluminum material (1) and the iron-based material (21) are joined by brazing via an aluminum layer (22) using a material to which one or both of the _two are added. A method for manufacturing a joining member with an iron-based material. 2. A method for manufacturing a joining member of an aluminum material and an iron-based material, wherein friction welding is performed on at least a peripheral portion of a joining surface of the joining member joined by the method of claim 1.