KR101401080B1 - A strip-cast aluminum-silicon alloy for brazing and Manufacturing method of the same - Google Patents

Abstract

The Al-Si alloy thin plate for brazing according to the present invention comprises 6.8 to 8.2% by weight of silicon (Si), 0.5% by weight of iron (Fe), 0 to 0.25% by weight of copper (Cu) (Mn) of not more than 0.1 wt%, zinc (Zn) of not less than 0 and not more than 0.2 wt%, magnesium (Mg) of not less than 0 and not more than 0.05 wt%, aluminum (Al) and other unavoidable impurities (Al-Si) alloy having a Vickers hardness (Hv) of 67.7 to 75.5 after thin-casting by a twin-roll casting method and cold rolling.
A method for producing an Al-Si alloy thin plate for brazing according to the present invention is characterized by comprising the steps of: 6.8 to 8.2% by weight of silicon (Si), 0.5% by weight or less of iron (Fe), and 0 to 0.25% (Mn) of more than 0 and not more than 0.1 wt%, zinc (Zn) of not less than 0 and not more than 0.2 wt%, magnesium (Mg) of not less than 0 and not more than 0.05 wt% and aluminum (Al) A step of casting the Al-Si-based alloy by twin-roll casting; and a step of cold-rolling the thin plate to obtain an Al-Si- And a cold rolling step of producing an Al-Si alloy thin plate for brazing having a Vickers hardness (Hv) of 75.5.

Description

[0001] The present invention relates to an aluminum-silicon alloy thin plate for brazing, and a manufacturing method thereof.

The present invention relates to an Al-Si alloy thin plate for brazing which is made by thin-casting an Al-Si alloy containing silicon (Si) by twin roll casting and then cold rolling to finen the main assembly to improve hardness, And a manufacturing method thereof.

The present invention relates to an Al-Si alloy thin plate for brazing and a method of manufacturing the same, in which energy consumption is reduced in the subsequent brazing process by lowering DELTA H during thin plate casting by thin plate casting by twin roll casting.

Since the aluminum alloy is lightweight and has high thermal conductivity, it is used in an automobile heat exchanger such as a radiator, a condenser, an evaporator, a heater, an intercooler, and the like. Automobile heat exchangers are mainly manufactured by the brazing method.

On the other hand, in the case of a heat exchanger for an indoor / outdoor use of an air conditioner manufactured by intubation after stacking aluminum pins, a manufacturing process by a brazing method has been attempted in recent years as a demand for weight reduction and miniaturization.

Typically, brazing takes place at a high temperature of about 600 DEG C using brazing filler metal of an Al-Si based alloy. Therefore, an aluminum alloy brazing sheet having excellent brazing property and high strength and corrosion resistance after brazing is required.

The aluminum alloy heat exchanger manufactured by brazing is mainly composed of a corrugated fin which is responsible for heat dissipation and a tube for circulating cooling water or refrigerant. If the tube penetrates by corrosion or fracture, leakage of cooling water or refrigerant circulating inside the tube occurs. Therefore, in order to improve the life of the product, an aluminum alloy brazing sheet excellent in strength after brazing and corrosion resistance is indispensable.

[0003] In recent years, there has been a growing demand for lightweight automobiles, and a lightweight automotive heat exchanger is also required to cope with this. Therefore, it has been studied to make each member constituting the heat exchanger thinner, and it is necessary to further improve the strength after brazing of the aluminum alloy brazing sheet.

This is also required in the case of an aluminum brazing sheet which is applied to a heat exchanger for indoor / outdoor use of an air conditioner.

Accordingly, Korean Patent Publication No. 2007-0061413 discloses a method for producing an aluminum alloy brazing sheet, which is manufactured by casting an aluminum alloy for a core material, an intermediate material and a sacrificial anode material to prepare a core material, an intermediate material and a sacrificial cathode material, homogenizing the material, Method "is disclosed.

However, in the case of an alloy containing a large amount of alloying elements, there is a problem that the unevenness of the casting structure is increased and the occurrence of defects is increased in the rolling joining and the subsequent rolling of the thin plate.

In addition, since it is manufactured through a lot of rolling processes, the productivity is lowered and a large amount of energy is required.

Meanwhile, the AA4343 alloy is an Al-Si alloy used as a braze metal for brazing an aluminum alloy used as a fin and a tube of a heat exchanger, and the content of Si is about 6.8 to 8.8 wt%.

The alloy has a process temperature of 579 ° C and is manufactured using the Ingot casting method (IC) method in a relatively wide range of temperature range of about 30 ° C to about 40 ° C.

In addition, intermediate heat treatment is required for good rolling even in the subsequent cold rolling due to the presence of the process Si particles. Therefore, when manufactured by IC casting, an increase in manufacturing cost due to the subsequent process is inevitable.

An object of the present invention is to solve the problems of the prior art, and more specifically, to provide a method of manufacturing an Al-Si alloy containing silicon (Si) by thin casting using a twin roll casting method, To thereby improve the hardness of the Al-Si alloy thin plate for brazing, and a method of manufacturing the same.

Another object of the present invention is to provide an Al-Si alloy thin plate for brazing, which is capable of reducing energy consumption in the subsequent brazing process by lowering DELTA H during thin sheet casting by thin casting by twin roll casting and a method for manufacturing the same And the like.

In order to achieve the above object, the present invention provides an Al-Si alloy thin plate for brazing, which comprises 6.8 to 8.2% by weight of silicon (Si), 0.5% by weight of iron (Fe) (Mn) of more than 0 and not more than 0.2 wt%, magnesium (Mg) of not less than 0 and not more than 0.05 wt%, and the balance of copper (Cu) (Al) and other inevitable impurities are thin-cast by twin roll casting and then cold-rolled to have a Vickers hardness (Hv) of 67.7 to 75.5.

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And has an? H of 380 J / g or less at the time of thin-plate casting by an Al-Si-based alloy containing silicon (Si) in a twin roll casting method.

A method for producing an Al-Si alloy thin plate for brazing according to the present invention is characterized by comprising the steps of: 6.8 to 8.2% by weight of silicon (Si), 0.5% by weight or less of iron (Fe), and 0 to 0.25% (Mn) of more than 0 and not more than 0.1 wt%, zinc (Zn) of not less than 0 and not more than 0.2 wt%, magnesium (Mg) of not less than 0 and not more than 0.05 wt% and aluminum (Al) A step of casting the Al-Si-based alloy by twin-roll casting; and a step of cold-rolling the thin plate to obtain an Al-Si- And a cold rolling step of producing an Al-Si alloy thin plate for brazing having a Vickers hardness (Hv) of 75.5.

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The cold rolling step is characterized in that the casting structure is miniaturized.

(Si), 0.5% by weight or less of iron (Fe), 0 to 0.25% by weight of copper (Cu), and 0 to 0.1% by weight of manganese (Mn) And an Al-Si-based alloy containing not less than 0.2% by weight of zinc (Zn) and not less than 0.05% by weight of magnesium (Mg) and the balance aluminum (Al) There is an advantage that the hardness is improved by refining the main assembly by cold rolling after thin casting by a twin roll casting method.

In addition, by thin casting by twin roll casting, energy consumption can be significantly reduced in the subsequent brazing process by lowering DELTA H during thin sheet casting, thereby reducing manufacturing cost.

Further, there is an advantage that the occurrence of defects is minimized because the thickness is thin and the composition deviation is not so large.

1 is a table showing the components of an Al-Si alloy thin plate for brazing according to the present invention.
2 is a photograph of an actual thin film of an Al-Si alloy for brazing according to the present invention.
3 is a flow chart showing a process for producing an Al-Si alloy thin plate for brazing according to the present invention.
Fig. 4 is a table showing the conditions of the thin plate casting step as one step in the method for producing an Al-Si alloy thin plate for brazing according to the present invention.
5 is a table comparing the reduction rates of Comparative Examples and Examples in the method for producing an Al-Si alloy thin plate for brazing according to the present invention.
Fig. 6 is a photograph of a practical example obtained by performing a thin sheet casting step as one step in the method for producing an Al-Si alloy thin plate for brazing according to the present invention.
7 is a table comparing the Vickers hardnesses of Examples and Comparative Examples obtained by performing the thin plate casting step.
8 is a photograph of an alloy thin plate having completed the cold rolling step as one step in the method for manufacturing an Al-Si alloy thin plate for brazing according to the present invention, and crack measurement data for evaluation of cold rolling property.
Fig. 9 is a photograph of a thin alloy thin plate of comparative example and crack measurement data for evaluation of cold rolling property after hot rolling. Fig.
10 is a microstructure photograph showing the casting state of the alloy thin plate of the preferred embodiment of the present invention and the alloy thin plate of the comparative example and the state of the Si particles after cold rolling.
FIG. 11 is a graph comparing changes in solidus temperature and liquidus temperature with changes in temperature during casting according to preferred embodiments and comparative examples of the present invention. FIG.
FIG. 12 is a graph showing changes in ΔH according to a temperature rise temperature during casting, according to a preferred embodiment of the present invention and a comparative example.

Hereinafter, an Al-Si alloy thin plate for brazing will be described with reference to FIGS. 1 and 2 attached hereto.

FIG. 1 is a table showing the components of an Al-Si alloy thin plate for brazing according to the present invention, and FIG. 2 is a photograph of an Al-Si alloy thin plate for brazing according to the present invention.

Prior to this, terms and words used in the present specification and claims should not be construed in a conventional and dictionary sense, and the inventor may appropriately define the concept of the term in order to describe its invention in the best possible way It should be construed as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents It should be understood that water and variations may be present.

As shown in the accompanying drawings, an Al-Si alloy thin plate for brazing according to the present invention (hereinafter referred to as an "alloy thin plate") is manufactured by thin-plate casting an Al-Si alloy containing silicon (Si) Followed by cold rolling to have a Vickers hardness (Hv) of 67.7 to 75.5.

That is, the alloy thin plate has a composition of 6.8 to 8.2% by weight of silicon (Si), 0.5% by weight of iron (Fe), 0 to 0.25% by weight of copper (Cu) Manganese (Mn), zinc (Zn) of not less than 0 and not more than 0.2 wt%, magnesium (Mg) of not less than 0 and not more than 0.05 wt%, aluminum (Al) remaining inevitable and other unavoidable impurities.

The alloy thin plate has improved strength by refining the main assembly through the cold rolling after the thin plate casting and controlling the temperature rise temperature per minute at the time of thin plate casting by the twin roll casting method of the Al-Si based alloy at 380 J / g or less.

That is, the alloy thin plate has? H of 380 J / g or less when controlling the temperature increase rate per minute at 20 占 폚 or more during thin sheet casting, thereby significantly reducing the amount of heat applied during the manufacturing process.

Hereinafter, a method of manufacturing the Al-Si alloy thin plate for brazing according to the present invention will be described with reference to FIGS. 3 to 5 attached hereto.

FIG. 3 is a flow chart showing a process for producing an Al-Si alloy thin plate for brazing according to the present invention. FIG. 4 is a schematic view showing a process for producing a thin Al-Si alloy for brazing according to the present invention, FIG. 5 is a table showing comparison of reduction rates of Comparative Examples and Examples in the method for producing an Al-Si alloy thin plate for brazing according to the present invention.

The method for manufacturing an Al-Si alloy thin plate for brazing according to the present invention comprises a material preparing step (S100) for preparing an Al-Si alloy containing silicon (Si), a step of preparing the Al- (S300) for producing an Al-Si alloy thin plate for brazing having a Vickers hardness (Hv) of 67.7 to 75.5 by cold rolling the thin plate by a thin sheet casting step (S200) .

In the material preparing step S100, the Al-Si alloy is dissolved in the crucible at a temperature of 720 ° C using commercially available pure aluminum (purity: 99.86%) and an Al-20 wt.% Si parent alloy to produce 6.8 to 8.2 wt% (Si), 0.5 wt% or less of iron (Fe), 0 to 0.25 wt% of copper (Cu), 0 to 0.1 wt% of manganese (Mn), and 0 to 0.2 wt% Zinc (Zn), magnesium (Mg) in an amount of more than 0 and 0.05 wt% or less, aluminum (Al) remaining, and other unavoidable impurities.

In the thin plate casting step (S200), the molten alloy having the above composition was allowed to stand at 680 DEG C in a molten metal injector while casting at a rate of 3 mm per minute using a twin roll thin plate casting machine.

Then, asymmetric nozzles were applied so that the contact lengths of the upper roll and the lower roll directly contacting the molten metal were 40 and 35 mm, respectively, and the roll interval was set to 3 to 4 mm.

The Al-Si alloy thin plate manufactured in the thin plate casting step (S200) is as shown in FIG. 6, and the thin plate manufactured in the thin plate casting step (S200) has a thickness of about 4 to 5 mm.

After the thin plate casting step (S200), a cold rolling step (S300) is performed. In the cold rolling step S300, the thin plate is cold-rolled under no-lubrication condition without heat treatment to obtain an Al-Si alloy thin plate for brazing having a final thickness of 1 mm. In the cold rolling step S300, Thereby enhancing the hardness.

FIG. 7 is a table comparing the Vickers hardnesses of Examples and Comparative Examples obtained by performing the thin plate casting step. In Comparative Example, the same alloy as the Al-Si alloy prepared in the material preparation step (S100) (W) x 30 (t) mm, hot rolled at a temperature of 400 DEG C to a thickness of 4 mm, and cold rolled to prepare a steel sheet having a thickness of 1 mm.

Hereinafter, the cold rolling properties of Examples and Comparative Examples of the present invention will be described with reference to FIGS. 8 and 9.

FIG. 8 is a photograph of cracks measured for a real photograph and an evaluation of cold rolling property of a thin alloy plate in which the cold rolling step as one step in the method of manufacturing an Al-Si alloy thin plate for brazing according to the present invention is completed, And crack measurement data for cold rolling evaluation after hot rolling.

As shown in the figure, in Examples 1 and 2, cracks of 1.4 to 3.5 mm occurred at the upper and lower ends, and cracks of 6.0 mm at maximum, whereas Comparative Example showed a maximum crack length of 7.5 mm, It was confirmed that the cold rolling property was better than the comparative example.

Hereinafter, the particle states before and after the cold rolling step (S300) will be described with reference to the preferred embodiment and the comparative example with reference to FIG. 10 attached hereto.

10 is a microstructure photograph showing the casting state of the alloy thin plate of the preferred embodiment of the present invention and the alloy thin plate of the comparative example and the state of the Si particles after cold rolling.

As shown in the drawing, in the embodiment of the present invention, after the completion of casting, the process structure was segregated at the main assembly boundary, and uniform distribution of Si grains could not be obtained.

However, after the cold rolling step (S300), it is confirmed that most of the cast structure is decomposed to form uniform microstructure.

On the other hand, after the completion of casting in the comparative example, the main assembly was formed largely than the examples, and it can be confirmed that the Si particles are formed as needle-shaped or coarse Si particles at the main assembly boundary.

The alloys of the comparative examples were subjected to the hot rolling process after cold rolling without direct cold rolling in the casting state, and then cold rolling was performed. As a result, it was found that the Si particles were very coarse and they were distributed in the band shape in the rolling direction.

FIG. 11 is a graph comparing changes in solidus temperature and liquidus temperature with changes in temperature during casting according to a preferred embodiment and a comparative example of the present invention. And the change of? H with the temperature rise temperature change.

Referring first to FIG. 11, the solidus (processing reaction) temperature of the alloys of the Examples was higher than the solidus temperature (577 ° C) of the AA4343 alloy, which is generally known in all specimens, Not observed.

As the heating rate increases, the solidus and liquidus temperatures rise, which is considered to be due to insufficient time to reach melting. The liquidus temperature was also slightly higher than the known liquidus temperature (612.8 ° C) for the AA4343 alloy.

As shown in FIG. 12, ΔH gradually decreased in the order of Example 2, Example 1, and Comparative Example when the heating rate was 10 ° C., and ΔH decreased as the heating rate increased.

The ΔH of the alloy of Example 1 and that of the alloy of Example 2 are similar to each other at a heating rate of 20 ° C. or higher, while ΔH of the alloy of Comparative Example is relatively higher than that of the alloys of Comparative Example.

Therefore, it is expected that brazing will be possible by lowering the brazing time or lowering the energy consumption by lowering the temperature compared to the existing brazing temperature.

The scope of the present invention is not limited to the above-described embodiments, and many other modifications based on the present invention will be possible to those skilled in the art within the scope of the present invention.

S100. Material preparing step S200. Sheet metal casting step
S300. Cold rolling step

Claims (7)

delete (Si), 0.5% by weight or less of iron (Fe), 0 to 0.25% by weight of copper (Cu), 0 to 0.1% by weight of manganese (Mn) An Al-Si-based alloy containing not more than 0.2% by weight of zinc (Zn) and not less than 0.05% by weight of magnesium (Mg) and the balance aluminum (Al) (Hv) of 67.7 to 75.5 by thin-plate casting by twin roll casting so as to have a DELTA H of 380 J / g or less under an elevated temperature condition of not less than 30 DEG C and not more than 3 DEG C, and having a Vickers hardness (Hv) of 67.7 to 75.5. Si alloy thin plate.
The Al-Si alloy thin plate for brazing according to claim 2, wherein the Al-Si alloy thin plate for brazing has a fine structure in the cold rolling.
delete delete (Si), 0.5% by weight or less of iron (Fe), 0 to 0.25% by weight of copper (Cu), 0 to 0.1% by weight of manganese (Mn) An Al-Si-based alloy composed of not more than 0.2% by weight of zinc (Zn), not less than 0 and not more than 0.05% by weight of magnesium (Mg), aluminum (Al) remaining in the balance and other unavoidable impurities is prepared A material preparation step,
A thin plate casting step of casting the Al-Si based alloy at a temperature elevation temperature of 20 DEG C or higher per minute to have an DELTA H of 380 J / g or less by twin roll casting;
And a cold rolling step of cold-rolling the thin plate to produce an Al-Si alloy thin plate for brazing having a Vickers hardness (Hv) of 67.7 to 75.5.
7. The method of claim 6, wherein the cold rolling comprises:
Wherein the step of forming the Al-Si alloy foil is a process of refining the casting structure.

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