KR101169315B1 - Alloy composition for filler metal and arc brazing method for Zn-coated Steel sheet - Google Patents

Abstract

The present invention relates to a filler metal composition and an arc brazing method for a surface-treated steel sheet using the same. In the present invention, by using a copper alloy wire containing a filler metal composition containing a specific content of copper, silicon and zinc as the filler metal, it is possible to perform arc brazing at low current, low heat input conditions, thereby resulting in stable arc formation It is possible to bond the surface-treated steel sheet with little spatter generation. In addition, the arc brazing method of the present invention can perform more precise and beautiful arc brazing of the surface-treated steel sheet.

Description

Alloy composition for filler metal and arc brazing method for Zn-coated Steel sheet}

The present invention relates to a filler metal composition and an arc brazing method for a surface-treated steel sheet using the same.

In general, welding is divided into fusion welding, welding using filler metal, and welding, welding without filler material. In the fusion welding and soldering, the base materials are bonded to each other through the filler metal between the welded materials (base materials) to be joined. In this case, the fusion welding is a method of melting and welding the welding portion and the filler metal of the base material at the same time, the soldering is a method of melting and joining only the filler metal without melting the welding portion of the base material, the soldering point having a melting point of about 427 ℃ or less (Soldering ) And a brazing having a melting point of about 427 ° C. or more.

Arc brazing is a welding method in which an electric arc is used as a heat source and a metal or an alloy having a lower melting point than a base material to be joined is used as a filler metal without joining the base metal. The filler metal used for arc brazing is mainly copper alloy wire, and includes copper-silicon alloy type (Cu-Si type) containing silicon and / or manganese or copper-aluminum alloy type (Cu-Al type) containing aluminum. This is commonly used. In particular, copper-silicon alloy wires have a lower melting point than copper-aluminum wires and are suitable for arc brazing by short arcs of low current. In addition, arc brazing is less suitable for welding of thin plates, such as automobile body parts, because the welding deformation is smaller than that of molten welding such as gas metal arc (GMA) welding, and joints having a large gap can be joined. In addition, arc brazing requires a protective gas, like arc welding, in order to protect the electric arc from the atmosphere, and argon gas is generally used as a protective gas, and most arc brazing is a copper-silicon-manganese (Cu) filler metal. -Si-Mn) copper alloy is used.

However, the melting point of the Cu-Si-Mn-based copper alloy is relatively high, such as 910 ° C to 1025 ° C, resulting in higher average welding current and higher heat input, thereby generating pores at the welding interface. And thermal damage is caused. As a specific problem, defects, such as defect of a weld bead, damage to the surface of a plating layer, or melt | dissolution, are mentioned. In addition, when a copper-silicon-manganese (Cu-Si-Mn) -based copper alloy is used as the filler metal and argon gas is used as the protective gas, the cathode point is not stabilized, and the generation of arc becomes unstable. spatter) occurs, and the bead width deteriorates, causing bead meandering. Particularly, when it is applied to the joining of surface-treated steel sheets such as galvanized steel sheets, the width of the beads tends to be narrower, and the contact area between the weld metal and the base metal is also narrowed. Since the construction of the inevitable, there is a problem that the destabilization of the arc and the generation of spatter is further increased.

As an attempt to overcome this problem, there is a brazing method using a laser as a heat source and a copper-silicon-manganese (Cu-Si-Mn) -based copper alloy wire as the filler metal, but since the laser is a high-density heat source, the brazing of the surface-treated steel sheet Porosity is easily generated at the welding interface, expensive and expensive, and the processing precision of the joint has to be very high.

Accordingly, development of filler metals capable of performing arc brazing under conditions of low current and low heat input has been required due to its relatively low melting point.

An object of the present invention is to provide a filler metal composition and an arc brazing method of a surface-treated steel sheet using the same.

The present invention as a means for solving the above problems, 94.5 parts by weight to 97 parts by weight of copper (Cu); 2.5 to 4 parts by weight of silicon (Si); And it provides a filler metal alloy composition comprising 0.5 to 1.5 parts by weight of zinc (Zn).

The present invention provides a copper-silicon-zinc (Cu-Si-Zn) -based copper alloy wire comprising the filler metal composition according to the present invention in the arc brazing method of the surface-treated steel sheet as another means for solving the above problems Provided are an arc brazing method for a surface treated steel sheet used as a filler metal.

When using a copper-silicon-zinc (Cu-Si-Zn) -based copper alloy wire containing the filler metal composition according to the present invention as the filler metal, bead defects, arc instability and spatter even when arc brazing is applied to the surface-treated steel sheet By drastically reducing the occurrence of data, it can greatly contribute to productivity improvement and cost reduction. In addition, arc brazing can be performed under low current and low heat input conditions, thereby significantly improving the bonding quality through arc brazing of a superior and beautiful shape.

1 is a view schematically showing an arc brazing method of a surface-treated steel sheet according to an aspect of the present invention.
2 is a photograph showing a state (a) of a surface-treated steel sheet on which a normal weld is formed and a state (b) of a normal weld bead.
3 is a photograph showing a state (a) of a surface-treated steel sheet in which welding is not properly formed and a state (b) of a weld bead in a bad state.
4 is a photograph showing the appearance of the molten surface-treated steel sheet during welding due to excessive heat input.
5 is a photograph showing a spatter generated in large quantities during welding due to excessive heat input.

94.5 parts by weight to 97 parts by weight of copper (Cu); 2.5 to 4 parts by weight of silicon (Si); And 0.5 parts by weight to 1.5 parts by weight of zinc (Zn).

EMBODIMENT OF THE INVENTION Hereinafter, the filler metal alloy composition of this invention is demonstrated concretely.

The filler metal alloy composition of the present invention may include copper. The copper is a main metal component constituting the filler metal alloy composition, and the content thereof is not particularly limited, but is preferably 94.5 parts by weight to 97 parts by weight, more preferably 95 parts by weight to 96 parts by weight of the filler metal composition. It may be included in parts by weight. If the content of copper is less than 94.5 parts by weight, the strength may be lowered, and if it is more than 97 parts by weight, the melting point may be increased.

The filler metal alloy composition of the present invention may include silicon. The silicon is included in the filler metal alloy composition as a component for improving the compatibility with the base metal, thereby lowering the melting point, improving the flowability and permeability of the filler metal, and causing vaporization of zinc, which has a detrimental effect on workers. Can be prevented. The content of the silicon in the present invention is not particularly limited, but may be preferably included in 2.5 parts by weight to 4.0 parts by weight, more preferably 3.0 parts by weight to 3.5 parts by weight based on 100 parts by weight of the filler metal alloy composition. If the content of the silicon is less than 2.5 parts by weight, the compatibility with the base material may be lowered. If the content of the silicon exceeds 4.0 parts by weight, the flowability and permeability of the filler metal may be lowered.

The filler metal alloy composition of the present invention may also comprise zinc in conjunction with the aforementioned copper and silicon. Since zinc is an element having a low melting point, it may be included in the filler metal alloy composition to help lower the melting point of the filler metal.

In the present invention, the content of zinc is not particularly limited, but may be preferably 0.5 parts by weight to 1.5 parts by weight, more preferably 1.0 parts by weight to 1.5 parts by weight. In the present invention, by controlling the content of zinc within the above range, it is possible to arc brazing under the conditions of low current and low heat input, and when the arc brazing of the galvanized steel sheet is similar to the plating layer components, it is easy to fuse with the plating layer, The strength of the joint can be greatly improved.

Melting point of the filler metal alloy composition of the present invention may be 800 ℃ to 900 ℃, preferably 820 ℃ to 880 ℃. By controlling the melting point of the filler metal composition within the above range, it is possible to perform arc brazing at low current and low heat input conditions, it is possible to significantly improve the bonding quality through the arc brazing of a superior and beautiful form.

The present invention also relates to an arc brazing method for a surface-treated steel sheet, the surface-treated steel sheet using a copper-silicon-zinc (Cu-Si-Zn) -based copper alloy wire containing the filler metal alloy composition according to the present invention as the filler metal It relates to an arc brazing method.

Hereinafter, the arc brazing method of the surface-treated steel sheet of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing an arc brazing method of a surface-treated steel sheet according to an aspect of the present invention. As shown in FIG. 1, the brazing torch 1 includes a gas nozzle 2, which is a hollow cylindrical structure, inside which a hollow cylindrical contact tip 3 is reduced at the same magnification. ) Is fixedly spaced at regular intervals. A flow path is provided between the gas nozzle 2 and the contact tip 3, and a flow path through which a protection gas flows is formed, and the flow path is connected to a protection gas supply source to provide a space for supplying the protection gas. In front of the contact tip 3, a copper alloy wire 4 used as the filler metal of the present invention is inserted, and the copper alloy wire 4 automatically supplied from a wire supply device (not shown) is continuously fed. It is configured to be.

In the present invention, the wire supply device is provided with a control unit to perform the operation of advancing or retracting the copper alloy wire (4), the control unit is the number of times per cycle, period, timing and copper alloy of the forward operation and the retraction operation It can be configured to appropriately set the movement amount of the wire.

In addition, in the present invention, there is a welding power supply device 6 capable of applying a welding current between the contact tip 3 and the base material 5, and the copper alloy wire 4 and the base material 5 are formed by the welding current. An arc can be generated in between. The arc melts the copper alloy wire 4 and at the same time preheats the base material 5, and the volume formed by melting the wire flows into the surface and the gap of the base material 5 to form a junction with the base material 5. .

In the arc brazing method of the present invention, the copper alloy wire used as the filler metal may include the filler metal alloy composition described above. By using the copper alloy wire containing the above filler metal composition as the filler metal, arc brazing of the surface-treated steel sheet can be performed under low current and low heat input conditions.

In the present invention, the type of the surface-treated steel sheet is not particularly limited, and for example, the plated steel sheet may be a form in which a surface treatment generally known in the art is performed. The type of the plated steel sheet is not particularly limited, and may be, for example, a galvanized steel sheet, a zinc alloy plated steel sheet, an aluminum plated steel sheet, or an aluminum alloy plated steel sheet.

In the arc brazing method of the present invention, arc brazing of the surface-treated steel sheet can be performed under low current conditions, and the low current conditions are not particularly limited, but preferably the average welding current is 40 A to 60 A, more preferably. 45 A to 55 A. If the average welding current is less than 40 A, not only the melting ability may be lowered and the copper alloy wire may not be sufficiently melted, but also the preheating effect of the base material may be low, making it difficult to form a normal welding bead. Porosity or spatter is likely to occur at the joint due to the increased melting amount of the copper alloy wire, and the base metal may be melted due to excessive welding current, or thermal damage may cause deterioration of the properties of the base metal.

In addition, in the arc brazing method of the present invention, arc brazing of the surface-treated steel sheet may be performed under low heat input conditions, and the low heat input conditions are not particularly limited, but the following general formula (1) is preferably satisfied.

[Formula 1]

300 (J / cm2) × T (cm) +120 (J / cm) ≤ Q (J / cm) ≤200 (J / cm2) × T (cm) +380 (J / cm)

In the general formula 1, Q represents the heat input amount, T represents the thickness of the steel sheet.

In addition, the Q (heating amount) can be obtained through the following general formula (2).

[Formula 2]

Q = (I × E × 60) / v

In Formula 2, I represents the average welding current (unit: A), E represents the average arc voltage (unit: V), v represents the brazing speed (unit: cm / min).

As described above, in the arc brazing method of the present invention, the amount of heat input is controlled according to the thickness of the base steel sheet to form a stable weld bead, and it is possible to prevent defects or spatter generation of the joint due to instability of the arc.

In the general formula 1, the thickness T of the steel sheet is not particularly limited and may be appropriately selected according to the use for which the surface-treated steel sheet is used, but is preferably 0.3 mm to 2.5 mm, more preferably 0.5 mm to 1.5 mm Can be.

In the arc brazing method of the present invention, the heat input amount is not particularly limited, but may preferably be 300 J / cm to 580 J / cm. When the heat input amount is less than 300 J / cm, it may be difficult to form a stable weld bead, and when it exceeds 580 J / cm, excessive melting of the copper alloy wire may cause the base material to melt or become unstable in the joint, Defects or spatters may occur.

That is, the arc brazing method of the surface-treated steel sheet according to the present invention by using a copper alloy wire containing the filler metal composition according to the invention as the filler metal, it is possible to perform the arc brazing at low current and low heat input conditions, It is possible to bond the surface-treated steel sheet in a state in which spatter is generated little by stable arc formation. In particular, in the case of using a galvanized steel sheet as a base material, the zinc component contained in the copper alloy wire as the filler metal is remarkably improved, and thus, finer and more beautiful arc brazing can be performed.

[ Example ]

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited by the following examples.

Example  One

Copper alloy Of wire  Produce

A Cu—Si—Zn-based copper alloy wire was prepared from a filler metal composition including 96 parts by weight of copper, 3 parts by weight of silicon, and 1 part by weight of zinc. Melting | fusing point of the said Cu-Si-Zn type copper alloy wire was 880 degreeC.

Arc of galvanized steel Brazing  practice

A galvanized steel sheet having a thickness of 1.0 mm was used as the base material, and the copper alloy wire prepared above was used as the filler metal, and as shown in FIG. 1, the arc brazing of the galvanized steel sheet was performed. At this time, the arc brazing was carried out under the performance conditions of the average welding current 50A and heat input 380 J / cm.

Comparative example  One

Arc brazing was performed in the same manner as in Example 1 except that the composition ratio of the filler metal composition was changed to 93 parts by weight of copper, 3 parts by weight of silicon, and 4 parts by weight of zinc. At this time, the melting point of the copper alloy wire was 930 ° C.

Comparative example  2

Arc brazing was carried out in the same manner as in Example 1, except that the composition ratio of the filler metal composition was changed to 93 parts by weight of copper, 6 parts by weight of silicon, and 1 part by weight of zinc. The melting point of the copper alloy wire was 1020 ° C.

Comparative example  3

Arc brazing was performed in the same manner as in Example 1 except that the average welding current was changed to 30 A and the heat input amount was changed to 290 J / cm.

Comparative example  4

The arc brazing was carried out in the same manner as in Comparative Example 2 except that the average welding current was changed to 70 A and the heat input amount was changed to 600 J / cm under the arc brazing performance.

Arc brazing performance conditions of the galvanized steel sheet of the Examples and Comparative Examples carried out are described in Table 1 below.

division Dragonfly  Alloy composition Arc Brazing  Execution condition Copper silicon zinc Copper alloy
wire  Melting point (캜) Average welding
Current (A) Heat input amount (J / cm ) Example  One 96 3 One 880 50 380
Comparative example One 93 3 4 930 50 380 2 93 6 One 1020 50 380 3 96 3 One 880 30 290 4 93 3 4 930 70 600 Content of filler metal alloy composition component unit: parts by weight

As a result of performing arc brazing of the galvanized steel sheet according to the Examples and Comparative Examples, the following physical properties were shown.

One. Test Example  One

The welding state of the arc brazing according to the examples and comparative examples of the present invention was visually observed.

As a result of performing arc brazing of the galvanized steel sheet according to Example 1 of the present invention, as shown in FIG. 2, a beautiful arc brazing joint was shown without welding bead defects, and there was no spatter generation. However, in Comparative Examples 1 and 2, as a result of the change of the composition of the filler metal composition, the melting points of the copper alloy wire were 930 ° C and 1020 ° C, respectively, exceeding the upper limit of the melting point of the filler metal composition according to the present invention. As a result, in the arc brazing performing conditions according to the present invention, as shown in FIG. In addition, in the case of Comparative Example 3, the average welding current and the heat input amount was low, a normal welding bead was not formed, and thus, sufficient bonding was not made as shown in FIG. In addition, in the case of Comparative Example 4, the average welding current and the amount of heat input was excessively melted to the galvanized steel sheet as a base material as shown in FIG.

1: brazing torch 2: gas nozzle
3: contact tip 4: filler wire
5: substrate 6: welding power supply

Claims (6)

94.5 parts by weight to 97 parts by weight of copper (Cu); 2.5 to 4 parts by weight of silicon (Si); And 0.5 parts by weight to 1.5 parts by weight of zinc (Zn). The method of claim 1,
The filler metal alloy composition having a melting point of 800 ° C to 900 ° C. In the arc brazing method of the surface-treated steel sheet,
A method of arc brazing a surface treated steel sheet using a copper-silicon-zinc (Cu-Si-Zn) -based copper alloy wire containing the filler metal alloy composition according to any one of claims 1 and 2 as a filler metal. The method of claim 3, wherein
A method of arc brazing a surface treated steel sheet having an average welding current of 40 amps (A) to 60 amps (A). The method of claim 3, wherein
An arc brazing method for a surface-treated steel sheet that satisfies the following general formula (1).
[Formula 1]
300 (J / cm2) × T (cm) +120 (J / cm) ≤ Q (J / cm) ≤200 (J / cm2) × T (cm) +380 (J / cm)
In the general formula 1, Q represents the heat input amount, T represents the thickness of the steel sheet. The method of claim 5, wherein
A method of arc brazing a surface treated steel sheet with Q of 300 J / cm to 580 J / cm.

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